American Aircraft for the RAF

Neutral Grey 43 ~ Some More Thoughts

2012-01-26T08:33:00.000-08:00

Consider the wide difference between NG 43 and FS 16492 as shown in the schematic prepared for the recent blog on this subject. Both colours are made with the same pigments, but to different ratios. Now perhaps consider how NG 43 might shift more towards 16492 - although not as light - if the amount of titanium oxide (white) and/or yellow oxide (ochre) was increased in the mix, or the amount of carbon black decreased. Could such a degree of variance be tolerated in the production of the paint? Consider also patch painting by maintenance crews where there was a good chance that tins of NG 43, unless prepared very thoroughly, could demonstrate unequal dispersion through settling where the greater ratio pigment, white, might predominate. And finally consider chalking which produces a whiteish grey patina on the paint surface.

When it comes to the RAAF P-40N a useful little book that explores the subject of applied paint in forensic detail is John King's 'The Whole Nine Yards', celebrating and commemorating the life of A29-448 (42-104730) and her restoration. There is a whole chapter devoted to this subject, providing a valuable insight to Curtiss factory paint application and colours This follows convention in matching the undersurface NG 43 paint to FS 36173 based on extant samples from A29-448 and other P-40's. but the following comment is made:-

"There is little evidence in the literature of wide colour shifts in the Neutral Grey lower surface paint, other than normal oxidisation of the surface layers, which is easily removed with a mild abrasive."

Geoff Thomas, in an article for Airfix magazine in February 1983 ('True Colours'), matched NG 43 to Munsell 5 PB 4/1 - the closest FA value to which is 36118 @ 2.06 (where 2.0 or less equals a close match). But even so, 36118 is visually more blueish than the Munsell value as shown. In his 'Eyes for the Phoenix' Geoff matched NG 43 to FS 36173, Methuen 22D-E2 and Munsell 6 PB 4.1/2.5. This variance probably represents matching to extant paint samples rather than a paint standard swatch. All these colours seem more typical for Sea Gray ANA 603 than NG 43.

The restorers of A29-448 were satisfied that the aircraft was in the Curtiss factory scheme and had not been repainted but the upper surface paint, assessed from extant samples from the airframe and from other P-40's where the paint surface had been protected from the environment (beneath flanges, fairings and panel joints, etc.) was darker and greener than might be expected. They matched it to FS 34083 rather than the more usually cited 34087 and commented that a can of US FS 24087 paint available to them was "browner than any US colour seen on any of the P-40 paint samples available to the owners of A29-448". Of note is that FS 34083 is the closest FS value to the MAP paint colour standard swatch for RAF Dark Green at a very close 1.14.

For those who like to experiment with primary pigments in mixing colours the pigments for FS 34083 are titanium dioxide (white), natural raw umber, chrome yellow (red shade) and carbon black (blue shade). One formula for Olive Drab provided to MAP specifies chrome yellow (or molybdate orange), chromium oxide green, pure iron oxides (red or yellow), titanium oxide and carbon black. This formula has been matched to FS 34084 which is very dark indeed.

On some long exposed and weathered P-40N airframes with degraded paint examined in the 1960's at the Rukuhia dump, the colours showed "the well known colour reversal of the Olive Drab and Medium Green disruptive pattern on the plan-view and vertical surfaces: the OD had weathered to green and the Medium Green had weathered to a light brown." But interestingly not all the airframes showed this reversal and when weathered samples were cleaned with an oiled cloth the reversal disappeared and the colours reverted to shades closer to those expected. This suggests strongly the effects of chalking and the application of paints of exactly similar colour appearance originally but of different pigment constituents, with those exhibiting more apparent colour shift probably containing a higher proportions of extender.

Medium Green 42 was supposedly used to obliterate the original US markings on some RAAF P-40N's, resulting in discs of an apparent lighter colour visible behind the RAAF roundel and codes in some photographs. One has to be careful here because the tonal differences seen in photos do not always coincide neatly with the colour differences of the actual paint. Medium Green 42 is another colour for which there are various equivalents cited, including FS 34092 which seems rather desaturated or faded. FS 34092 is also sometimes cited as a match for RAAF Foliage Green but extant samples of that paint are much darker and more olive. Foliage Green would seem a more likely paint colour for the over-painted markings but the tonal differences to the OD are almost in reverse to what is seen in the photos. Some references maintain that Medium Green 42 and Foliage Green were identical colours. The applied paint might have ended up appearing very similar but the Medium Green standard is not the same as extant samples of Foliage Green examined.

Geoffrey Pentland* suggests that Foliage Green was used to touch up the OD paint on the RAAF P-40N's, including Atherton's 'Cleopatra III'. He also reports that some P-40 undersurfaces (e.g. in 86 Sqn) were re-painted Sky Blue but as mentioned elsewhere the supposedly unpainted ailerons appear much lighter in photos than the darker undersurfaces, rather than the other way around. Most P-40N's seemed to have retained the NG 43 undersurfaces and it seems more likely that the ailerons, subject to maintenance, replacement and re-covering, were re-painted Sky Blue or a lighter grey like Medium Sea Grey which Pentland describes as fading "quickly to a near-white colour which then required repainting". Many of the aircraft were kept polished which deepened and intensified the colours.

Interior colours are covered in 'The Whole Nine Yards' too, with the author citing the formula from the Preliminary Handbook of Erection and Maintenance Instructions for the P-40N:-

Zinc Chromate Primer (AN-TT-P-656) 100 Gallons
Titanium Oxide (AN-TT-P-436) 1.3 lbs
Lampblack (TT-L-71) 0.1 - 0.4 lbs
or Carbon Black (AN-TT-C-121) 0.1 - 0.4 lbs
Magnesium Silicate (Commercial) 8-10 lbs

The points to note here are the variable amount of black in the mix and the addition of white (especially for those who assert that Interior Green was a mix of only Zinc Chromate Primer and Black). The author points out that the curiously confusing layout of this section could have resulted in both Lampblack and Carbon Black being added to the mix, as well as the variable proportions which would affect the final colour appearance. Some hobby paint interior greens are quite garish and "leap out" on models, perhaps the result of formulating colour based on flash photographic images of cockpits, but it is an illuminating exercise to mix the colour using the specified constituent pigments, including real Zinc Chromate rather than "yellow". The variance in black might have been specified to compensate for a yellow-green variance in AN-TT-P-656 in order to better match the standardisation for Interior Green (ANA 611) as ANA Bulletin 157 on 28 Sept. 1943 had stated:-

"ANA 611 Interior Green is intended for standardisation of the product obtained by tinting zinc chromate primer, Specification AN--TT--P--656, for shop coat or interior finish purposes."

The Dictionary of Aircraft Maintenance Terms, Section H Paint and Dope (T.O. No. 30-1-2-H) published by HQ ATSC in November 1944 defines 'Primer, Zinc Chromate' as follows:-

"A semi-transparent, greenish-yellow liquid of zinc chromate base, thinned with toluol, very generally used as a primer on aircraft metal surfaces. Because it dries quickly, coats of lacquer, enamel, etc., can be applied on top it within a few minutes, though it is best to allow the primer to set for a few hours."

(Toluol or Toluene was an industrial grade solvent widely used in lacquers, paints and synthetic enamels.)

* RAAF Camouflage & Markings 1939-45 Vols 1 & 2 (Kookaburra Technical Publications Pty Ltd., 1980)

Neutral Gray 43 ~ The Clue is in the Name

2012-01-05T08:59:00.000-08:00

Something of a departure from regular fare - again - as a discussion at Britmodeller about the best hobby paint to represent the USAAC paint colour Neutral Gray 43 (NG43) triggered some thoughts on the matter. Regular readers will know that one of the motivations behind this blog is an attempt to separate colour facts from colour fictions - or perhaps more correctly from colour 'myths'. Not necessarily in any kind of revisionist or heretical way, although that often seems to be the result, but by examining what is actually known, as dispassionately and objectively as is possible and applying established colour science to it. This is more often than not contrary to perpetuating what is thought to be known and which, when investigated, is sometimes found to be based on unreliable or even obscure foundations.

The first reality check with NG43 is the idea it that it was a "pure" neutral grey consisting only of black and white pigments. It wasn't. The pigments specified for NG43 in 14105 (camouflage pigmented nitrate lacquer) and 14106 (camouflage pigmented nitrate dope) were titanium dioxide, yellow iron oxide and lamp black. More on these pigments later.

The second reality check is that there is only one colour value in FS 595B that approximately matches these pigments (see below) and none that match the colour. And this is further borne out by conducting colour comparisons to crunch the numbers. There is not a single FS value that comes even close to the 2.0 or less requirement of the DE2000 difference calculation criteria. The FS values most often cited for NG43, FS 36270 (supposedly in error) and 36173 (supposedly correct) both contain rutile titanium dioxide (white), phthalocyanine blue (red shade) and carbon black (blue shade). In addition 36270 contains benzimidazolone yellow whilst 36173 contains red iron oxide (blue shade). This is not surprising as contrary to what is often asserted NG43 did not evolve into any other standard colour after its appearance in Bulletin 41 of Sep 16 1940. It was replaced by the ANA paint colour Sea Gray 603 introduced in ANA 157 on Sep 28 1943 and that evolved to become FS 36118.

The closest FS value to NG43 is FS 36152 @ 3.54. However, it is still more blueish in appearance and the constituent pigments are rutile titanium dioxide, phthalocyanine green (blue shade), chrome yellow (red shade) and carbon black (blue shade). Chrome yellow is a stronger, brighter and clearer yellow pigment than yellow oxide. The closest FS value to NG43 in pigment content terms is FS 16492 which contains almost exactly similar pigments of rutile titanium dioxide, yellow iron oxide and carbon black but it is clearly much lighter than NG43 as a result of ratio differences.

I do not know where the idea of a blueish NG43 comes from, but there is a prevalent tendency for "greys" to be perceived as blueish and many of the NG43 hobby paints seem to show this trait. Even though many modellers repeat the popular idea that NG43 was a pure mix of black and white they seem comfortable with accepting these blueish grey hobby paints as representative and in citing FS 36173 as a match! Perhaps this operates on the "decorator principle"? I also get the impression that a lot of these matches are being made under artificial hobby room tungsten light which draws 36173 closer to a warmer, neutral grey. Certainly the swatch included in J F Dial's 1964 'United States Camouflage WW II' (Scale Reproductions) is significantly more blueish in chroma than the paint chip and printed chip in both the Archer books*. Again I emphasise that the discussion here concerns the paint colour standard and does not necessarily mean that all applied paints matched that standard perfectly and/or did not exhibit colour shift as a result of manufacturing processes or environmental and age related stresses. Please, no more colour photographs to "prove" points about paint!

Another clue to the real characteristics of the colour is the fact that for the first time in Spec 14057-C of 27 Dec 1939 Munsell colour notations had been cited for the colours and Neutral Gray 32 was notated as Munsell N5 (in the 1929 system). Neutral Gray 32, an earlier temporary camouflage paint, was identical to the subsequent NG43. The 1929 Munsell N5 is entirely consistent with the Archer chips.

Both Testors (#1725) and Xtracolor (X133) versions of Neutral Gray are said to be matched to FS 36270 and 16270 respectively, but the Testors paint is actually manufactured only with titanium dioxide (15-20%) and carbon black (0.1-1.0%), although it contains hydrous aluminium silicate (an extender also known as China clay) and magnesium silicate (a filler also known as 'talc'). I haven't tested the Testors but I presume it to be a genuine neutral gray in colour? The Xtracolor paint appears as a very close match to FS 26270 but is a little lighter and warmer. White Ensign Models (WEM) Colourcoats ACUS13 WW2 USAAF Neutral Gray has the hybrid designation "ANA 43' (NG43 was never a ANA paint colour). It is a tad darker and slightly more blue-green in hue than FS 36173.

Titanium dioxide (C.I. pigment white 6) was developed in the 1920's and was in wide scale use as a white pigment by the 1950's. Prior to its use white pigments used in paints were compounds such as lead carbonate, zinc oxide, antimony oxide, lead silicate, lead sulfate and co-precipitated forms of these compounds. Other than zinc oxide most of these other forms of white pigment have become obsolete, not least because of issues of toxicity. It is manufactured in two processes, by sulfate and by chloride from ores such as ilmenite or rutile. In the sulfate process the ilmenite ore is reacted with sulfuric acid to produce titanyl sulfate, which is then hydrolised to produce hydrated titanium dioxide. This in turn is then calcinated to produce titanium dioxide pigment. There are two main forms - rutile, with resistance to chalking - and anatase, with a tendency to chalk significantly.

As a digression, another reality check for modellers is the prevalent idea that only the sun degrades paint and then only to "fade" it. In the exposure environment the chemical and physical processes affecting a paint surface are complex, combined and cumulative as it is subjected to diverse and variable environmental stresses. The most significant are heat, oxygen, sunlight, water (both in liquid and vapour form), mechanical and thermal stresses, atmospheric pollutants and various chemicals which might be applied to it, usually deliberately to clean it or unintentionally from materials or solvents associated with other servicing or maintenance activity. The paint film also contains decreasing levels of residual solvent or water, or both, retained after application, as well as pigments, fillers, additives or trace metal impurities incorporated during manufacture - all of which will probably have some photochemical activity. The physical effects that can be expected include gloss loss, colour change, dirt retention, chalking, cracking, delamination, blistering, fouling and corrosion.

The typical effects of chalking result in a whiteish-grey powdery patina across the surface which is not that obvious to the eye unless you rub your hand over it. Titanium dioxide is both a UV-activated oxidation catalyst and a UV absorber, with a tendency to absorb light at the blue end of the spectrum and to appear as a yellow toned white. As an oxidation catalyst free radicals are formed on the surface and oxidise the binder by photocatalytic degradation. This reduces any gloss and produces a friable layer on the surface of the paint film. The process will be exacerbated under direct UV exposure but even surfaces out of direct light will not be immune, for example a combination of extremes of heat and humidity will cause a similar degradation. Any paint that contains a majority of the anatase form titanium dioxide (such as greys and light blues) would tend to exhibit more chalking, which is why Ocean Grey, say, can appear to "fade" much lighter than adjoining Dark Green. A common fallacy of modellers is to assume that all camouflage paint colours "fade" or degrade at the same rate.

The effect of chalking on a grey paint would be to make it appear lighter (and with other colours lighter and more greyish) but typically the surface would be variegated rather than even in appearance, especially where it has been subjected to different degrees of exposure. How much lighter the grey becomes depends on the duration of exposure and degree of degradation, reaching a point where it could be almost off-white in appearance and ultimately where the paint breaks down through the whole film and begins to reveal the primer. Regular maintenance treatment will reduce the chalking process or delay it but not eradicate it entirely.

Now, to return to NG43, what should make us think that the form of titanium dioxide used in the paint was anatase? Well, the same specifications make a point of requiring the "anti-chalking" variety of titanium dioxide for the Insignia White and Insignia Blue paints, a requirement omitted for NG43, which strongly suggests (and no more than that) that NG43 could be manufactured using the anatase form of the pigment.

Yellow oxide - or yellow iron oxide - exists in synthetic (CI pigment yellow 42) and natural forms (CI pigment yellow 43) It is produced synthetically by hydrating ferric oxide to a range of dull reddish-yellow to yellowish-orange brown hues, the final colour determined by the size of the particles in turn controlled by rate and duration of oxidisation and the concentration and pH of solutions. Yellow iron oxide is not therefore an identifiable colour by name alone. It is a relatively cheap pigment used extensively to produce cream tints with titanium dioxide. In common with red oxides it provides good light fastness (colour retention) and heat resistance, absorbing UV radiation to an extent which gives good durability. It has good opacity and good chemical resistance. It has poor tinting strength which means that when added to, say, titanium dioxide, a lot goes a very little way and the shades produced by it are usually dull rather than bright. Why was it added to NG43? Possibly to counter the chalking tendency of the titanium dioxide or to counter a blueing tint from the use of blue shade carbon black. The effect of a titanium dioxide and yellow oxide combination would certainly produce a warm tint grey rather than a cool blue-grey.

Lamp black (CI pigment black 7), not to be confused with carbon black (pigment black 6) although related and sharing the same CI # 77266, is commonly used by the paint industry to produce a superior black colour. Carbon Black is much better in colour and tinctorial value than Lamp Black but the difference between their structures is not completely understood. Carbon blacks are often known by the name of the hydrocarbon they are made from, e.g. Acetylene Black or Benzol Black. It is usually made by heating oil, gas or acetylene at very high temperatures with limited air. It has a very small particle size which can cause dispersion problems leading to poor gloss and poor colour. It can also have stability issues in air drying media and when combined with other pigments such as titanium dioxide it can flocculate, changing colour in storage. In pigment form, far from being constant, the hue varies from deep brownish or bluish or greyish to deep black.

* The Official Monogram US Army Air Service & Air Corps Aicraft Color Guide, Vol.1 by Robert D Archer (Monogram Aviaton Publications, 1995) and USAAF Aircraft Markings and Camouflage 1941-1947 by Robert D and Victor G Archer (Schiffer Publishing 1997).

Seasons Greetings

2011-12-21T06:29:00.000-08:00

Chris Huhne models his Department's answer to rising winter fuel costs. The pensioner's own breath is re-circulated to warm the lining of the Lib Dem Xmas Utility Suit.

Wishing all friends of American Aircraft for the RAF a Very Merry Christmas and a Happy New Year

Image credit: Secretary of State for Energy and Climate Change

That Old Chestnut - The Can of Worms

2011-12-20T02:35:00.000-08:00

Modellers often describe colour related issues as a "Can of Worms", usually as a preliminary to drawing their own particular conclusion in one of those published celebrity builds which are avidly followed and where, by dint of modelling expertise, the sometimes contrarian choice of paint colours is often taken as some form of definitive guide. This is not always appropriate. In colour terms the plaudit "That looks good" is not always synonymous with "That is accurate" or even "That is close enough".

"Can of Worms" is usually taken to mean "a source of unforeseen and troublesome complexity". What it doesn't really mean is "different opinions in the absence of hard data". That is just speculation and/or disagreement. The arguments and counter-arguments involved might be based on hypotheses which might include elements of complexity - or not. What it certainly doesn't mean is an absence of data per se. But because we live in an online world where it is much easier to present an opinion as a hypothesis, or to promote a hypothesis via an opinion, the distinction between complexity and the simple unknown is sometimes blurred. As a consequence the vacuum of the unknown is all too often filled with unverifiable assertions and counter assertions. Over time these become confusing to anyone trying to ascertain the base data - or lack of it. It is the speculation that often becomes the can of worms, not the base data or absence of data which for an objective mindset usually remain unchanged.

A case in point is the Brewster Buffalo. As built for the RAF we can presume with some confidence that it was painted in colours intended to represent the RAF Temperate Land Scheme (TLS) of Dark Green, Dark Earth and Duck Egg Blue (Sky). Nothing complex or "can of worms" about that. What we don't know is exactly what those paint colours were like or how far they differed from the MAP Standard colours. AFAIK there are no accessible extant paint samples, no colour photographs, no factory paint specifications and no paint company swatches (at least not Fuller). There are contemporaneous descriptions, subjective as well as subject to interpretation, and there may be contemporaneous colour paintings. Speculation about the probabilities and possibilities around these unknowns is not a can of worms - it is just speculation.

Some modellers understandably approach builds where there is an absence of solid colour data with trepidation and there is these days a more evident need for reassurance - or consensus - about the colours to be chosen. Whether this arises from some harsh judgements or snide comments at model shows I couldn't say but the notorious "colour police" waiting to pounce on the wrong RLM seem, at least online, to be an urban myth. Sure there is debate and disagreement, often heated, over colours, but very rarely is a model displayed online criticised harshly for its paint choices - even when it deserves it. Nevertheless "can of worms" often appears as a plaintive, to discourage a mythic storm of criticism (it seldom discourages a storm of heated discussion). But ask yourself, next time you comment on model colour, whether approval or disapproval rests on the "decorator principle" ("I like the pretty colour you have painted your model. I'm going to do the same") or the "accuracy principle" ("I think the colour looks correct, based on the verifiable data available"). Nothing really wrong with either, except when they pretend to be each other.

In modelling the expression "can of worms" is not just misused, it is over used. It is a cliché. And it is all too often, sadly, a cloaking device for ignorance. So choose colours and paint your Buffalo with confidence, in the freedom and joy of objective interpretation - not in the angst of seeking a consensus of speculation. Just my two cents worth . . . . .

Dupont, FS and MAP colours

2011-12-01T03:31:00.000-08:00

The question of FS 25622 matching Dupont 71-021 came up in an offline conversation as a colour comparison site has suggested it as a match for MAP Sky Blue (together with FS 25550). The schematic above shows the colours.

FS 25550 is the closest FS colour to MAP Sky Blue but it is not a particularly close match @ 5.51 where less than 2 = a close match. It is lighter and brighter. FS 25622 is close enough to the Munsell value of 71-021 to be considered a useful match but the original colour has a slightly stronger chroma.

These variances are probably not worth worrying over in modelling terms because in addition to the expected variables in manufacturing processes most of the under surface light blues and light blue-greens contained anatase Titanium Dioxide (white) as their main pigment, together with China clay extender. Both these ingredients cause severe chalking of the paint surface which after a few months of exposure and depending on the environment and maintenance regime will make the colour appear significantly lighter and more greyish-white. Having said that there is still a need to represent the colour in an identifiable way so 25622 would not be the best FS colour to represent MAP Sky Blue.

Seen in isolation it is easy to perceive 25622 as a cool "light blue" but the colour actually has a green aspect and is a pale blue-green. MAP Sky Blue is a cool, sightly greyish light blue, not as strong chromatically as many seem to think. The Sky/Duck Egg Blue formula was too subtle and too imprecise for the paint technology of the time to produce consistent results so variance was inevitable. Also, whilst paint manufacturers were given swatches to match against and the preferred pigment formula "solution" was suggested it was not mandatory. Manufacturers were free to select their own pigment formulae provided the applied paint matched the swatch. What happened afterwards was unpredictable as pigments, whilst creating the same or similar enough colours using different formulae, age and degrade in different ways. Even in the modern FS 595B standard the procurement process allows for the "Visual Evaluation of Color Differences of Opaque Materials" (ASTM D 1729) on the basis of whether a critical or general match is required. This subjective, visual evaluation allowed for an inspector to decide what was "close enough" so incremental variances between pale blue-greens towards more green or more blue could be expected to pass through the process. But the inspectors were not stupid and neither were the staff of the handling and receiving units so it would be wrong to suggest that "close enough" could include paints formulated to completely different hues, such as neutral greys. Establishments in Britain testing specific aircraft types from manufacture were expected to report on all aspects, including whether camouflage paint was "acceptable" in both colour and quality of application.

Another thing to bear in mind is that many contemporaneous observers not versed in the official paint names would probably see and describe these colours simply as "green" and "brown", the under surface colour being "light blue", "duck egg blue" or "sky blue" all interchangeably. The subtle nuances of these paint colours are often important only in hindsight and from a modelling perspective.

The tendency for paints of the time to chalk badly was well known and although I have no specific evidence for it I suspect that the more deeply saturated paint colours applied in US manufacture recognised this and were intended to compensate for it, especially where procurement was under commercial contract.

Receiving units in Britain included "sister" firms charged with providing maintenance and manufacturing support for specific US aircraft manufacturers and aircraft types. This support extended to thorough documentation concerning the paint colours applied to aircraft, even to itemising their pigment compositions, in order to assist in the procurement of matching paints in the UK. The whole process, whilst acknowledging the realities of aircraft and paint production, was by no means as cavalier or as casual as some modellers believe and would have us believe. In the case of the Douglas Bostons the strong blueishness of their under surface colours was the subject of both comment and complaint at the time. So far I have not encountered a single reference to paint colours expected to be supplied as "duck egg blue" actually being grey.

Brewster Buffalo Colours

2011-11-29T14:03:00.000-08:00

The current thread on Brewster Buffalo colours at Britmodeller gives me pause for thought. In January this year I wrote in another thread at Britmodeller:-

"I do have reliable measured colour values for the Du Pont upper surface browns and green from the original swatches but have not prepared or published rendered chips and comparisons yet. When I started comparing the colour values that had been given for these hues in the past (FS, Pantone, Methuen, etc.) I found disparities between them that were impossible to reconcile - probably the results of attempts to match subjectively and visually under different forms of illumination and perhaps from colour photos. The paints are very much deeper and more strongly saturated than MAP colours and the dark green has a different character entirely to MAP Dark Green, being more of a forest green in appearance than an olive green. One thing I can confirm and that is that the dark green is not like 34092 at all - the difference calculation to that is over 15 where less than 2.0 = a close match but I guess "scale colour" may come into this. The full scale paint does look very dark indeed but colour photographs reveal how it faded under uv exposure. I have nothing on the Fuller paints yet."

Since then I have published rendered chips of the Du Pont TLS colours here in August together with a comparison to the MAP colours they equate to. The closest FS match to the green is 14056 and for the darker of the two browns 26120. The lighter brown is close to 30140. The difference calculations are 0.87, 2.73 and 0.75 where < 2.0 = a close match so they are all useful comparisons, although the darker brown is a little lighter and not so chocolate in appearance as 26120. FS 34092, often cited for Dupont 71-013 is the same basic hue (Munsell 4.7 G 3.5/1.9 vs 1.5 G 2.0/1.7 but is significantly lighter and de-saturated than the actual paint colour, as though representing a very faded version. It's a personal choice but on a 1/72nd scale model I would probably select a tone somewhat between 14056 and 34092, moving more towards 14056 for models in larger scales. Even allowing for "scale colour" the dark green needs to look like a "dark green" rather than a "bright green" on a model!

The mention of Fuller paints is pertinent because I now have good reason to believe that Brewster procured Fuller paints for their export aircraft and those used on the Buffalo might have been the same as those applied to the Douglas Boston:- Fuller enamel TL-8713 Brown, Fuller enamel TL-8714 Green and Fuller enamel TL-8715 Blue (Duck Egg). Unfortunately I have not yet been able to find any charts, swatches or chips for these paints and the only clues as to their appearance are the Getty Images colour photographs of Bostons that I posted on the blog in June 2010.

Reading the current thread at Britmodeller drives home to me just how absolutely pointless it is posting this sort of data.

Airfix Curtiss Hawk 81-A-2

2011-10-21T03:03:00.000-07:00

There is a big spread on Airfix's new 1/72nd Curtiss Hawk 81-A-2 in Issue 12 (November 2011) of the Airfix Modelworld magazine. The kit offers only a single markings option for an aircraft of the famous Flying Tigers (American Volunteer Group or AVG). A previous post here revealed that the under surface colour suggested in the Airfix kit is Humbrol Matt 28 Camouflage Grey. This has now been confirmed by examination of this excellent kit. The magazine goes further in providing a splendid multi-view profile of the subject aircraft calling out the Humbrol and FS 595B colours - 116 Matt US Dark Green (No FS), 117 Matt US Light Earth (FS 30219) and 28 Matt Camouflage Grey (FS 36622). These are all called out as approximate equivalents to the correct Du Pont paint designations 71-013, 71-009 and 71-021. Unfortunately they are not. The Du Pont paints were darker and had a higher chromatic intensity (being more saturated) than the MAP paint colours and there is some doubt whether 71-009 or 71-035 (or both) were applied to the AVG Tomahawks. The closest FS match to the very dark Du Pont green is 14056 which is nothing like Humbrol's 116 even allowing for oxidising, chalking and fading of the paint surface. However, the box artist Adam Tooby has done a good job of representing the colours in his dramatic image.

A build article is included in the magazine where the author Tony O'Toole uses Humbrol equivalents for RAF Dark Earth, Dark Green and Sky to represent the colours on the AVG aircraft. This is arguably a more representative choice than the colours suggested by Airfix and, dare I say it, makes his superb model "look right". He refers to Sky as a "worthy alternative" for the under surface colour.

The plot thickens just a little. Humbrol 28 is reported to be a match for FS 36622 whereas there is no match in the Humbrol range for the FS equivalent of Du Pont's 71-021 Sky Type S Grey which is 35622. The colour value 36622 arose in a discussion at Hyperscale and was reported here but I still don't know whether this was in error for 35622 (a typo) or based on an interpretation of colour photography or on something else. Having said that it might not be such a bad choice to represent the heavily oxidised and chalked appearance of the paint colour on an AVG model. It is certainly a preferable choice to US Aircraft Grey/ANA 512/FS 36473/Tamiya Sky Gray but ironically, it is the suggested upper surface colours that are probably more contentious!

The Colours of RAF/AVG Tomahawks Part Three

2011-09-28T03:30:00.000-07:00

AK139 displays the TLS but appears to have an over-painted or 'censored'

Sky fuselage band and no codes showing. It served with 241, 268 and 231

Sqns before flying into the ground at Saintfield, County Down on 3 Jul

1942. (Note similarity in tone of spinner and under surface colour in this view.)

Following the December 1940 Fighter Command decision to reject the Tomahawk as a fighter aircraft for the European theatre, in January 1941 the Air Staff decided to trial the aircraft in a single Army Co-operation squadron with a view to eventually re-equipping three Lysander squadrons with the type. Army Co-operation Command had been seeking a replacement for the Lysander and had considered both the Hurricane and the Blenheim. The majority of the Tomahawk contract deliveries would be sent to the ME but the reality was that their numbers in the UK exceeded the shipping space available for consignment and the Air Staff considered the type suitable for the Army Co-operation role "as the latest American fighter type with a speed of 350 mph".

Soviet Tomahawk in TLS with Sky fuselage band and over-painted roundels.

In the late summer of 1941 the first batches of Tomahawks from RAF stocks also began to be shipped to the Soviet Union. The first 47 Tomahawk IIBs arrived in September 1941. The first arrivals were assembled by an RAF unit at Yagodnik airfield outside Archangel and were flight-tested by two American pilots attached to the RAF as 'combat observers' - Lts Zemke (subsequently the USAAF 56th FG commander) and Alison who also instructed Soviet pilots in their operation. The first two Tomahawks assembled, AK300 and AK242 were formally accepted by the Soviets on 5 October 1941. Other deliveries were AH971, AH974 to AH985, AH987 and AH994. Their service record is beyond the scope of this resource but AH975 (shown above) was photographed after delivery, still wearing RAF TLS with a Sky fuselage band, dark spinner (possibly re-painted) and the upper surface RAF roundels overpainted in a dark colour (possibly dark green) with red stars superimposed. In the photographs the overpainting appears to be darker and glossier than the original Dark Green of the TLS. The undersurface roundels had also been painted out in a glossier paint than the original under surface paint, which in some photos appears lighter and in others darker, with red stars applied over them. The whole fin (and RAF fin flash) appears to have been re-painted in a dark colour more closely matching the original camouflage and the rudder and ailerons re-doped in a slightly lighter colour. The Soviet photographs of the aircraft are sufficiently clear to show that the Sky fuselage band appears lighter than the under surface paint colour, even allowing for the effect of shadow.

In-flight view of AH925. Sky spinner and fuselage band appear paler than under

surface colour as described by M J F Bowyer. Note pattern, variegation and weathering of upper

surface paint. Stencil under oil filler spout in rear glazing reads "For oil use Shell grade 170"

In some photographs the RAF and Soviet Tomahawk under surfaces appear pale and bright, in others significantly darker. It would be convenient to be able to demarcate this appearance to early and later serials to conjecture some significant shift in painting practice but unfortunately it doesn't work out like that. The appearance is haphazard and the same aircraft can also appear differently in different photographs. Attempting to define colours from monochrome tones is fraught with difficulty because tones are so dependent on the type and direction of illumination when the photograph was taken as explained in the last blog post. Early Tomahawk deliveries were manufactured at a time when Sky was only just being introduced in the TLS for fighters and was being described as 'duck egg blue' to American manufacturers. This might explain the near to MAP Sky Blue colours recorded on some Tomahawks (and other US types), but in reality any variance could just be due to production batch differences and/or photographic tones.

One of the issues with the insistence that the paint applied to the under surfaces of AVG (ex-RAF) Tomahawks matched US Aircraft Grey is that this was never a camouflage paint colour but instead a gloss paint colour. The evolution of US paint colour standards shows it first appearing as ANA 512 in ANA 166 of 4 Dec 1943 so how it could have been deliberately chosen as a substitute colour standard for duck egg blue, Sky or even Sky Grey in 1940/41 is beyond comprehension. ANA 512 Aircraft Gray became 1645 in TT-C-595 of 1950 but was then replaced by FS 16473 (note 16473 - gloss). The previous Light Gray (125 in Bulletin 3-1 Revised of 21 April 1943) did not appear in ANA Bulletin 166 but was superceded by 1750 in TT-C-595 of 1950 and replaced in turn by FS 13578 in FS 595 of March 1956. The devil is always in the detail and the hypotheses so assuredly promoted by some often overlook or ignore the inconvenient but ever important chronology. Even were it to be accepted that this colour match is based only on the appearance of the Tomahawk under surface paint in colour photographs (rather than an assertion that Aircraft Gray paint was actually used) it is probably worth citing Robert D Archer's admonition in his introduction to the US paint colour standards in the mighty 'USAAF Markings and Camouflage 1941-1947' (Schiffer, 1997):-

"Color photographs reproduced with varying degrees of accuracy in various books and magazines during the last fifty years have been offered as evidence of variations in USAAF standard colours. These variations are mainly due to indifferent color separations and/or variation in inks used in the color printing process. The author has not found any evidence of such color variations in viewing original USAAF color material. Variations from regulation paint schemes and colors did exist in the field, particularly in the early days of the Pacific war theater, but this was under dire combat conditions and decidedly not the norm for the USAAF."

The Tomahawk, it will be remembered, was being painted for the RAF well before the USA was in the war - or indeed applying camouflage to its own aeroplanes. But even in respect of the much touted idea that the US adopted a more freewheeling approach to the subject of specifications and paint colours there is something pertinent from Mr Archer:-

"Finally, a word of caution; do not assume that the USAAF was prepared to accept batches of paint that did not meet its standard color requirements. For example, ANA Bulletin No.102b, dated April 30 1945, Army-Navy Aeronautical Bulletin, Lacquer; Cellulose Nitrate, Spec. AN-L-29 states:-

"1b. The listing of products in this bulletin does not waive the inspection requirements of the specification. The furnishing of paint which proves to be unequal to the test samples submitted, may be sufficient cause for removing the product and the manufacturer's name from the list."

2. The failure of a product furnished by the parent company or any authorized plant or affiliate will result in the removal of the product from the approved list and thus prohibit the furnishing of the material by either the parent company and its plants or affiliates until such time as satisfactory requalification has been completed by the parent company."

So much for a freewheeling disregard of requirements! The aeroplane and paint manufacturers knew what was at stake and no amount of convenient homespun hindsight or questionable analogy can alter that documented record. But even accepting a generic premise that what was required was not always done, so far not a single shred of substantive evidence has been offered for scrutiny or to support the specific assertion that a light gray paint was applied instead of paint matched (however imperfectly) to duck egg blue and Sky, even before the question of precisely what the colour value of that light gray paint might have been. So far it is a speculative hypothesis based wholly on selective colour photographs and distinguished by an unequivocal presentation which disregards all evidence to the contrary. As such it is a literally incredible argument. One might as legitimately say that the appearance of RAF spinners and fuselage bands in some colour photographs demonstrates that they were not painted in Sky but rather in white or cream. All the more remarkable then that it has gained such traction with modellers and with kit, decal and even paint manufacturers. One prominent decal manufacturer has even described the under surface colour of RAF Tomahawks as "Du Pont Light Gray" as though inventing a paint colour name that was never officially used by Du Pont or Curtiss will somehow legitimise a hypothesis. Who might buck this trend?

In the schematic above the two colour values of Du Pont 71-021 (from the Curtiss supplied paint swatch and the Du Pont colour card chip) are presented in a gradient chip (left to right) juxtaposed against measured MAP colour standard values for Sky and Sky Blue. These illustrate standards so in order to envisage the reality of applied paints consider shifts to slighter lighter, "whiter" variants of Sky and slightly deeper (greener and yellower) variants of 71-021 (appearing as "duck egg green" as described by Mr Bowyer who noted in respect of RAF Sky that lighter shades were in evidence by 1941 and eventually a very pale shade in use by late 1943.). Or indeed shifts of both to slightly more blueish variants approaching Sky Blue - only very small incremental changes are required to push these colours from light blue green to light greyish blue. Bear in mind the tendency of RAF paints to chalk rapidly (whiten - perhaps one reason that the Sky standard appears so deep in chroma) and the effects of shadow - in photographs a true comparison must be at the point where the Sky band lies beneath the fuselage and against the under surface paint - but also the reflective qualities of differently manufactured paints. An informed decision and an individually interpretative conclusion on a model is perfectly legitimate. In practice the paint colours revolve around a "wheel" of paint manufactured to standard, batch differences from pigment and mixing variations, application processes, surface treatments and wear, and finally environmental degradation. That is not to say anything goes - the centre of the wheel is the paint colour value as intended by specification - but the revolving elements militate against a slavish precision in replicating the colours.

In Part 4 the history of the Tomahawk in RAF service in the UK and the change of scheme from TLS to DFS will be explored in more detail.

Photographic "Colour" in Monochrome Images

2011-09-27T02:44:00.000-07:00

Jim made a very pertinent comment on the second part of Tomahawk colours which I'll respond to here rather than add a lengthy comment to that thread.

The appearance of that photographic image is pretty consistent with Mr Bowyer's description of "duck egg green" where he implies that "Sky" (the spinner and fuselage band) was lighter and also with F/O Bingham-Wallis who described the RAF-applied fuselage band on the Buffalo as a shade lighter than the factory applied sky blue undersurfaces. However, as will be seen in Part 3 there are other photos of similar RAF Tomahawks that display much less contrast between these colours.

A couple of points to note on this. The first is my old soap box of paint colour standards versus applied paints. Although Sky appears in the standards as a surprisingly dark and saturated colour it is apparent that in practice (and as suggested by Mr Bowyer) the paints could be quite light, appearing almost white in some colour photos. The UK manufactured paints had a high proportion of white extenders and tended to fade and chalk more rapidly (a characteristic which is the subject of criticism in a couple of RAAF reports as well as observations by Messrs Bowyer and Huntley) whereas the Du Pont paints had stronger pigmentation and tended to be more resilient in this respect.

Second is the question of illuminant effect and shadow. Modellers love to speculate and discuss colours based on the apparent tones seen in b/w photographs but the imagery, especially in digitally processed and formatted images, is inherently unreliable. I think too much faith is placed on the tones as they appear in images. Monochromatic tones on film emulsions are not paint - they are just the stimulations on film emulsion of the reflected wavelengths from the variously illuminated surface of paint. One of the best analyses of photographic tonal interpretation was published in Dick Taylor's 'Warpaint' in which he observes:-

"What is crucial is that we must always remember that the tone we see in Black and White photographs is dependent not only on the original colour(s) of the object, but also on the amount of light falling on any one particular area, so areas with tonal qualities (caused by shadows etc) can in fact be the same colour, or alternatively, the same tone can be produced by two different colours."

I would add that the type and direction of illuminant and the type of colour surface also has an effect. In paint the appearance of the colour surface is dependent on the reflected wavelength of the constituent pigments which can and do vary. So that paint colours falling ostensibly within the same family can actually possess different reflective properties. And there is also a difference between film sensitivity to colours and that of the eye. This is due to the fact that most panchromatic emulsions used are more sensitive to blue, violet and ultraviolet than to other colours so for example blues often appear paler in film than they do to the eye. The degree of blue pigmentation in colours such as these pale blue-greens and grey-greens can have a significant effect on how they appear on film - even before the effects of manipulators like filters are considered. In other words the constituent differences between the factory under surface paint and the RAF-applied Sky, even though visually similar to the eye, could appear tonally very different in a b/w image.

I don't know why these inherent factors are often so wilfully disregarded in discussions about colour from aircraft photographs but I suspect it is partly due to the strong modelling tendency to try to justify a preferred solution and/or that often deceptive faith in believing your own eyes. In 'Warpaint' Dick Taylor juxtaposes the same image of a British Army tank turret in monochrome and colour photographs. From the monochrome photograph you would swear that the squadron sign and tank name are the same colour because of their apparently identical tone. In the colour photograph it can be seen that the sign is red and the name is yellow!

PS In the schematic above the two dots on opposite sides are identical in tone - sRGB 153 153 153.

The Colours of RAF/AVG Tomahawks Part Two

2011-08-24T06:57:00.000-07:00

AH973 at Curtiss before despatch to the UK. It was lost at sea en route.

The AVG Tomahawks were drawn from batches intended mainly for the Middle East (ME), at first singly and then in pairs from the AK 100 to AK570 (36 aircraft) and AM370 to AM519 (64 aircraft) serials sequences, approximately every five aircraft. These sequences were delivered from December 1940 to October 1941 and from June to August 1941. It is unlikely therefore that they were specially painted for use in China as has sometimes been suggested in the past. Some references insist that the aircraft were diverted to China on Roosevelt's orders which "annoyed" the British but Meekcoms (in 'The British Air Commission and Lend Lease', Air-Britain 2000) makes it clear that were diverted at the request of Secretary Morgenthau (with British agreement) after delivery to the RAF. In that case they were shipped on to Burma from the ME.

AH925 served with the CFS, A&AEE and 30 OTU before being struck off charge in December 1944

The majority of Tomahawks delivered to the UK came from two batches in the AH serials range; AH741 to AH880 delivered from November 1940 to September 1941 and AH881 to AH999 delivered from December 1940 to September 1941.

Desert Air Force Tomahawk in TLS

As has been noted Tomahawks in the Temperate Land Scheme (TLS) delivered to RAF and Commonwealth squadrons in the ME have been described in squadron ORB's (Operations Record Book) as having a "grey-ish green" colour on their under surfaces. This sounds like a Sky or US Sky-equivalent colour and is consistent with the TLS. If subsequently documented Curtiss painting practice (for the Kittyhawk Mk.1) was being followed these aircraft should have had the 'lighter' Dark Earth 71-009 applied but it is apparent that, for whatever reason, the majority had the 'darker' Dark Earth 71-035 instead. These details raise interesting questions about the relationship of the DuPont paint colours to the introduction of the RAF Desert Scheme because deliveries of the Tomahawk had begun before that scheme was established. As delivered spinners were reported to be in Dark Earth or Black.

Tomahawk being ferried on the Takoradi Route to Abu Seir Egypt in TLS but with ferry

route number and "pancake" markings

The first Tomahawk was reported to have arrived in the UK in September 1940 and was from the first batch of aircraft taken over from an unfulfilled French contract. When photographed at Yeovil in early 1941 one of these aircraft AX900* shows a non-standard demarcation with the under surface colour raised high on the fuselage sides. The colour is unknown but MJF Bowyer who noted AX900 being tested at Boscombe does not remark on it. During the latter part of 1940 234 Sqn conducted brief trials with AH885, AH886, AH887 and AH889, following which, in December 1940, Fighter Command had rejected it as a fighter type suitable for European deployment.

DuPont Temperate Land Scheme Paint Colours

Before further considering the recorded colour schemes of UK-based Tomahawks made contemporaneously by M J F Bowyer it is pertinent to quote two general observations. In his introduction to Mr Bowyers 'Fighting Colours 1937-1975' (Patrick Stephens Ltd, 1975) Bruce Quarrie noted that:-

". . . much of the information in this book comes from his own records, in which he has eagerly been logging serial and code numbers as well as colour schemes since before the Second World War. It is thus 'eye-witness' material which provides a unique record to an era which all the efforts of the museums and preservation societies cannot bring back."

And in the preface to his book Mr Bowyer himself notes that:-

"Much of the material is from my own notes, most of them carefully and widely recorded throughout the period under review. Thus it is possible to put a specific date to many items and much hitherto unpublished material is also included. The book does not fall into the trap of quoting from official records and accepting them as a fait accompli. Therefore it may occasionally contradict some ideas held on the subject of fighter camouflage and markings."

As a source therefore Mr Bowyer is not to be dismissed lightly, despite the age of his reference work. Throughout his books his observations extend to recording anomalies and non-standard schemes and colours. There is a prevalent tendency today where some long-held beliefs have been revised or updated by new information to dismiss the whole of older reference works as 'outdated' or obsolete and to ignore them as a source. This is a mistake and runs the risk of throwing the baby out with the bathwater.

The other observation relates to the paint colour Sky (the subject of so much interest and heated debate by modellers on both sides of the Atlantic). Mr Bowyer notes that:-

"Throughout this book some attempt has been made to differentiate between fighters with 'Sky' undersides and those with the deeper shade here described as 'duck egg green'; the original official title 'Sky' was a generic term for some light shades developed in 1939. Light sea green was the shade chosen for use on bombers and fighters, re-named duck egg green - which is a better appelation than duck egg blue. Lighter shades are referred to as Sky in this book. These were in evidence by 1941 and eventually a very pale shade was used by late 1943. A possible explanation for the darker shades is that they were the result of mixes by RAF units, whereas the paler shades originated at the manufacturers. Darker shades were usually worn by the bombers of 2 Group whose Bostons and Venturas with the pale Sky shades looked most conspicuous."

This interesting observation introduces us to the reality than in terms of applied paints there were many variant shades of Sky and again it is worth drawing the distinction between a paint colour standard and applied paints. However, despite the variance, all these shades conformed generically to the Sky paint colour standard - in terms of nomenclature they were not different colours per se.

DuPont Temperate Land Scheme Paint Colours

Mr Bowyer records AH864 and AH861 at Duxford in April 1941, both "camouflaged Dark Green and Dark Earth" with "duck egg green under surfaces". In addition "Sky spinners and rear fuselage 18 inch bands were worn". He notes that during the winter weeks the undersurfaces of the port wings were painted black, with the roundel on that wing outlined in yellow. Bearing in mind Mr Bowyer's note about Sky colours his description of the Tomahawks implies that the spinner and fuselage bands were a lighter shade to the under surface colour. This is reminiscent of the description of Brewster Buffalos by F/O Bingham-Wallis of 67 Sqn:-

"Our aircraft in Rangoon were painted pale blue under colour. Of the original 30 aircraft there, approximately 20 were painted half black and half blue beneath, ie. on the mainplane. Shortly after they were assembled and painted, (we painted the black) the Air Ministry orders were changed and the remaining aircraft were left as delivered from the manufacturers, pale blue underneath. The band of blue forward of the tailplane would be a shade lighter than the sky blue ".

The difficulty is in reconciling the descriptions of pale blue/sky blue with a deeper shade of duck egg green and the amount of "green" appearance in the paint colours must remain conjectural. There is a possibility that the Tomahawk deliveries arriving in the UK were completely re-painted in the 'correct' TLS but I have seen no evidence for it and it seems unlikely given the circumstances prevailing at the time. But note the reference to "pale Sky shades" on Bostons and Venturas, both imported US types, in Mr Bowyer's comments cited above. None of the AVG colour photographs suggest richer shades of duck egg green like the unit-mixed Eau de Nil or Sky Blue type hues being applied to RAF fighters in lieu of Sky.

Mr Bowyer recorded AH848 in similar TLS finish in August 1941 bearing the medium grey codes SP-Y. Although at first the TLS finish was retained by aircraft of army co-operation squadrons, Tomahawk aircraft from these units operating alongside fighter squadrons for rhubarb operations over France were gradually re-painted in the Day Fighter Scheme (DFS) but as late as September 1942 Mr Bowyer recorded AH947 and AK137 of 241 Sqn at Bottisham still in the TLS but without codes.

MAP vs DuPont TLS Comparison

*AX900 served with A&AEE, 41 OTU, 1471 Flt, 168 Sqn and 1681 Flt before being struck off charge in May 1944. According to Tim Mason in 'The Secret Years' (Hikoki Publications, 1998) AX900 was AH900 with a mispainted serial number. James Halley in 'Royal Air Force Aircraft AA100 to AZ999' (Air Britain, 1985) lists AH900 as serving with 41 OTU, 168 Sqn and 1482 Flt before being struck off charge in December 1944. He lists AX900 separately as a Curtiss Tomahawk I delivered in September 1940. Two other 'odd' serial Tomahawks were BK852 serving with 1 FPP (Ferry Pilot Pool) and after a landing accident in August 1941 transferred to 2673MU, and BK854 serving with A&AEE, 613 Sqn and 168 Sqn until struck off charge in January 1944. According to Halley both these aircraft were from the ex-French contract F-273 and were originally allocated serials AH742 and AH743. These are listed elsewhere, together with AH741, as having no record of delivery.

The Colours of RAF/AVG Tomahawks Part One

2011-08-22T12:56:00.000-07:00

With the imminent release of the new Airfix kit the subject of Curtiss Tomahawk colours for RAF and AVG subjects will probably be chewed over yet again and already a thread at Britmodeller has touched on some of the issues. Previous references, particularly those cited as supporting the idea of light gray under surfaces, get bandied about rather uncritically, so I think it is worth re-emphasising some of the substance of what has actually been recorded.

I already quoted from Terrill Clements 'American Volunteer Group Colours and Markings' (Osprey, 2001) back in January 2009 and felt the need to repeat that in the Britmodeller thread, but some of the other observations in his comprehensive and excellent study also bear mentioning here (my emphasis):-

"Curtiss employed DuPont enamel camouflage paints on its products in 1940-41, and this included the brown and green colours used on the pattern camouflage of the Tomahawks shipped to Burma. The Dark Earth brown colour (DuPont 71-065) appears to have been visually identical to Army Air Corps colour Rust Brown 34, while DuPont Dark Green (DuPont 71-013) was virtually identical to Army Air Corps Dark Green 30. Whether they were those specific colours is uncertain, but they are certainly indistinguishable from them, and also 'close enough' to the green and brown in use by the RAF."

"Curtiss employed other colours on its fighters. however, including a sandy earth brown colour (DuPont 71-009). This shade has no analogue in the pre-war American colour standards, but it is similar to British Light Earth, and was perhaps intended for use on Desert Air Force Tomahawks. Period colour photos suggest that this colour was used on a few of the AVG's Tomahawks instead of the darker brown. Second Squadron pilot Robert Layher recalls noticing that, when seen side by side, some AVG Tomahawks had more 'vivid' camouflage on top than others. But it is unlikely that many casual observers would have noticed any significant difference between the colours on Curtiss's products and those aircraft painted more exactly to British standards. Even fewer would have cared."

The first point to notice is the acceptance that DuPont paint colours were being used by Curtiss during the time period of Tomahawk production. There is no suggestion that other paints were used so the question immediately arises - why should the under surface paint have been an exception? And yet we are sometimes asked to believe the suggestion that for some reason, perhaps poor quality control, Curtiss procured different paint, of a different colour, for the under surfaces of Tomahawks rather than using DuPont's equivalent(s) to MAP Sky.

The second point, and it is an interesting one, is the suggestion of some AVG aircraft having a slightly different appearance to others. Exploring the production and serial number history of the aircraft sent to China this seems perfectly feasible as they were drawn from distinct production batches. There are some issues about the way these deliveries have been described that will be explored in a future post.

DuPont's 1942 MAP colour card shows the 'darker' Dark Earth to be 71-035 rather than 71-065 but the latter might just be the result of a typo or misreading somewhere along the line (71-065 was actually Deep Sky Blue!). The allocation of the number 71-021 for DuPont's Sky Type S Grey suggests that this was not a later colour although there are no Curtiss documents that tie it conclusively to Tomahawk production. I doubt that the 'lighter' Dark Earth 71-009 was based on MAP Light Earth as DuPont offered this paint colour separately as 71-048 and in the early days of the Desert Scheme Light Earth was an authorised substitute for Middle Stone. It is more likely that the different Dark Earths relate to the camouflage contrasts intended to be achieved by the Temperate Land and Desert schemes. The Curtiss P-40E factory paint drawing (showing AK571) makes it clear that 71-035 was intended for the Desert Scheme whilst 71-009 was intended for the Temperate Land Scheme. This raises an interesting question about the AVG Tomahawks which will be addressed in due course.

In an article on Kittyhawk colours in the September 2002 IPMS Seattle Chapter newsletter Mr Clements wrote (again my emphasis):-

"The absence of a DuPont stock number for the “Sky Type S” is perhaps not accidental. Period color photographs reflect that in practice export Kittyhawks were finished with colors that tended toward either a pale blue or a pale gray. Some students of the subject still believe that a color that actually looked pretty close to RAF “Sky” (you know, that sickly yellow-green-gray color) was used as well, although photographic evidence of this is lacking. A similar range of blue and gray shades can be seen in color photos of export aircraft built by other manufacturers during this period. The Bell Corp. in fact identified “Sky Type S Grey” on a January 1941 Airacobra painting diagram as DuPont 71- 021, and the few color photos of P-400 Airacobras suggest to me that this was a color very much like RAF Sky Blue. It should be noted that DuPont also referred to 71-021 as Duck Egg Blue. Some color photos suggest that a light blue used by Curtiss also looked much like RAF Sky Blue, and that Curtiss’ light gray looked very much like RAF Sky Grey (or the very similar US Aircraft Gray). Considering the nature of such “sky” camouflage colors and the inherent limitations of photo interpretation, these colors perhaps merely represent extreme manufacturing variances of one specification. But it seems more likely that this was an attempt to respond to confusing directives. (If you can find them, read wartime British camouflage directives, and just try to figure out the bottom colors!) Or perhaps the gray paint was simply an expedient substitution for the blue due to shortages or a perceived need to somehow find a middle ground between US Army and RAF requirements. Or all of these!"

And he concluded that:- "Curtiss’ “light blue” was DuPont 71- 021 Duck Egg Blue, a color very similar to RAF Sky Blue."

Here are three actual samples of MAP Sky Blue as applied to RAF aircraft illustrating the slight variance to be found in the applied paints, together with a sample of DuPont 71-021 shown adjacent to a sample of MAP Sky.

Despite the apparent differences I think Mr Clements' conclusion about the appearance of 71-021 is a reasonable one, especially as samples of paint from the undersurface of a Soviet Tomahawk recovered in Russia are also very similar in appearance to MAP Sky Blue. Although the colour card chip of 71-021 appears closer to MAP Sky and slightly more greenish the actual paint samples are cooler and more blueish, giving the impression of a paint colour almost midway between MAP Sky Blue and MAP Sky. However, DuPont also included Sky Blue as a separate colour in its MAP range of paints as 71-061 and it appears to be a stronger more saturated blue than the MAP colour. What was it used for?

I have an abiding belief, based on snippets of evidence relating to Grumman Martlet, Brewster Buffalo and Curtiss Mohawk colours that early US attempts to match to Sky - or more correctly "duck egg blue" - resulted in cooler, more blueish colours similar to MAP Sky Blue and DuPont Sky Blue. When we come to examine RAF Tomahawks the snag in this belief will become apparent!

An issue with the comparison and matching of US Aircraft Grey (ANA 512) to MAP Sky Grey was addressed here in a post that also examined other greys proposed for Tomahawk under surfaces. In that post ANA 512 (based on a supposed match to FS 36473) appears slightly more greenish than Sky Grey which was a true neutral grey consisting only of black and white pigments. However I discovered that this slight grey-green appearance of Aircraft Grey (ANA 512), especially as it relates to FS 36473, might be fugitive. The pigments used in Aircraft Grey were Titanium dioxide ( a pure white at about FS 37875) and Carbon black (a dead black at about 37038), resulting in a neutral grey without any other colour tinting. The "neutrality" of a neutral grey can sometimes only be properly appreciated by comparing it directly to a "warm" grey (tinted yellow) or a "cool" grey (tinted blue or green) but there is a recognised tendency for all neutral greys to appear blueish under certain illuminants. The selection of Aircraft Grey as a possible colour value for Tomahawks seems to have been based on this idea that US manufacturers must have resorted to existing US colours as matches for the RAF colours and then looked for the closest colour to Sky Grey. With the established existence of 71-021 and its identified appearance I'm not sure that supposition was/is valid.

To be continued.

Airfix Hawk 81-A-2

2011-08-18T02:55:00.000-07:00

Sadly and despite the ambiguity of the box art a little bird tells me that Airfix will suggest Matt 28 Camouflage Grey for the under surface colour of their AVG Tomahawk. The Tamiya Sky Grey syndrome strikes again.

As the saying goes "A lie can get halfway around the world while the truth is still putting its boots on" and nowhere is this more apparent than in the whole sorry saga of the Tomahawk's supposed "sky grey" under surfaces. I'm not even going to bother to demolish 28 as a match to Dupont's 71-021 from a colour science perspective - what's the point? And I'll say nothing about the lined up Zeros either!

Image credit: © Airfix 2011

RAAF Curtiss P-40E and P-40E1

2011-02-26T04:26:00.000-08:00

Courtesy of Australian Researcher Michael Claringbould of Aerothentic Grafix comes this fascinating insight to early RAAF P-40E colour schemes together with excusive colour profiles.

A29-88 depicted above was Kittyhawk P-40E-1, British code ET445. A unique marking to RAAF 76 Sqn Kittyhawks in mid-1942 was their shortened fin flashes. CO Sqn Leader Peter Turnbull mostly flew P-40E A29-92 (Abdul the Bull). The prefix 'I' was added to the squadron codes to distinguish them from 75 Sqn Kittyhawks in the same theatre around the July 42 period of this mission. Abdul the Bull is portrayed the day it was lost at Milne Bay on 27 August 1942 and cost Turnbull his life. It is still unclear to this day why he crashed.

Early RAAF 75 Sqn Kitthawks were a mixture of either U.S marked P40Es (finished in Olive drab with Neutral grey underneath), or the P40E-1s. These had been finished initially in the Curtiss applied equivalents of RAF Dark green, Dark earth and Sky or as USAAF P40E aircraft with the US star (with red central disc) applied at the factory and “U.S.Army” under the wings. P40E-1s had the British roundel supplied along with USAAF stars shipped with them in their crates as loose items, pending allocation. This explains the application on delivery of some early RAAF P40E1’s of yellow outlined 1941 RAF Roundels. The P40E-1 "RAF" Dupont colours were slightly different to the MAP colours used in Britain, but nonetheless were in stark contrast to the Olive drab and Neutral Grey of the USAAF P40s.

Following delivery at Townsville all newly assembled P-40E-1s had their yellow roundel surrounds and fin flashes overpainted if they were received that way. They also had their Box Number and British Purchasing Commission Serial removed, as well as any USAAF markings. They also had their upper surface finish of olive drab overpainted with RAAF Dark Earth camouflage to the same pattern as the P-40E-1s but retained Olive Drab in place of Dark Green and Neutral Grey under surfaces. All roundels were of standard RAAF Blue/White/Red pattern and size on fuselage and underwing locations, with standard Red/Blue on the wing upper surface. Initially there were no fin flashes - these appeared just before the Kittyhawks flew to Port Moresby. Single-letter individual squadron codes were allocated. These changes have been confirmed by Australian researchers and ex-ground crew who participated in the work.

Whilst the P40E and P40E-1 had identical top cowlings, the P40E-1 had provision for ring and bead sights for night fighting and backup.

RAAF 75 Sqn Kittyhawks were delivered in one major batch, with the occassional add-on. Initially around early March 1942, most of the first 25 flew with their respective USAAF Box numbers/ET Serial markings and paint schemes (both USAAF OD and RAF Dupont). The A29 serial numbers were not applied until about 14 March 1942 for the surviving 21 P-40Es in Townsville.

From some of the less recorded USAAF wrecks/accidents of the February and March 1942 period, a few repaired P-40Es that made up some of the first RAAF “25” had been previously damaged in early USAAF service. For example s/n 41-5594 was one of seven so far identified P-40E/E-1s supplied from USAAF stocks at Archerfield in the first week of March 1942. This particular aircraft was part of a shipment which had been unloaded from the SS Mormac Sun on 21 January 1942 and used initially by the first five USAAF Provisional Squadrons

Each batch of P-40Es had its Line Number (often quoted as c/n or asn) marked in at least three locations on the airframe, one of which was on fuselage longeron #5. Using information from P-40 crash sites in Australia and PNG as well as some others worldwide, it has been possible to reconstruct the correlation between the Line Number and the AAF serial for this production block. Another number identifier is the Tail Box Number. This number was applied to the tail of each aircraft and their shipping crates when they were readied and crated for shipment from the United States. These were painted either in black or white and therefore should not be confused with post March/April 1942 individual USAAF squadron Buzz numbers of the 49th Pursuit Group.

Several Russian Lend Lease P-40E’s were diverted to Australia at this time. All USAAF Markings, including the USAAF datablock on the left /port side cockpit area had been removed before crating for Russia and USAAF serial identification has again been made through the recorded Line Number. This denuding of USAAF Markings lasted until the United States entry into the war. An example of one of these was P-40E 41-5535. Originally destined for the USSR following its acceptance on December 6 1941 by the USAAF, it was reversed from Defence Aid per contract DAR-42-381 and sent as part of the Project “X” shipments to Australia. Arriving on the USS Hammondsport in Brisbane, it was assembled and accepted in USAFIA service on February 22 1942. From there, it was transferred to RAAF service as A29-48 on March 18 1942. Later it became one of the attrition P-40Es sent to Port Moresby for use with 75 Sqn and was lost on May 2 1942.

The process of standardising paint schemes on RAAF P-40s lagged behind headquarters requirements. Operational demands were so strong at this time that there was simply not enough time to repaint every aircraft, so several P-40Es in squadron service remained in USAAF Dark Olive Drab, eg A29-28.

Son of Lassie 1945

2011-02-23T05:25:00.000-08:00

Oh dear. I've just been watching 'Son of Lassie' made in 1945 and shot in Technicolor at RCAF Patricia Bay. A glimpse of it here. I'm not even going to try to describe the colours seen on the Bolingbrokes of 122 Sqn which seem to defy interpretation (Is that brown actually green? Or is the grey actually green?) but the Kittyhawks of 133 and 135 Sqns (?) are interesting and there are Venturas in white and USN colours too.

In the film may be seen P-40N's in US colouring of Olive Drab over Neutral Grey with blue spinners and black single-letter codes but which have been partially re-painted, the fresh OD (or Camouflage Dark Earth?) over the original US serials and insignia giving the impression of a two-tone brown scheme. There are P-40M's in grey and green "day fighter" colours, the grey appearing much lighter than Ocean Grey, with white (or Sky?) spinners, blue and white "ying yang" wheel covers and no fuselage bands. Even the national insignia look different with a lighter, brighter blue and red.

The film is recommended to any colour pundit who wants to relish the shock of seeing what we expect to see but not as we might expect it (!) and to any modellers looking for a very different scheme for that P-40!

Image credits: © Warner Bros

Du Pont 71-021 Again!

2010-09-25T04:36:00.000-07:00

At Hyperscale a Mr David C Jones asked for the FS value for Du Pont's Sky Type S Gray, 71-021, thinking that it was close to either Camouflage Gray (FS 36622) or Aircraft Gray (FS 36473) but being unable to remember. Steven "Modeldad" Eisenmann responded, posting not only links to this blog but an image of the 1942 Du Pont colour card which has been reproduced here in the past.

I think there is a distinction to be made between the actual colour of the Du Pont 71-021 Sky Type S Grey paint and the question of whether or not it was used to paint aircraft - (leaving aside the question of paint production and application variables for the present). In Steven's response he did not draw that distinction, going straight to the question of actual aircraft painting. I'm not sure what the two FS values for the Du Pont paint are based on but if you look at the Color Server version of 36622 it appears similar to the colour seen in the heading photograph. The actual 595B chip is another matter. That is quite precise matching but the process by which it has been arrived at is difficult to determine.

The ARC discussion that Steven also linked to contains some bold statements regarding the published references of Tom Tullis (on AVG colours) and Dana Bell and I have endeavoured to address some of these here in the past. Tom Tullis' statement that there was no Du Pont paint equivalent to MAP Sky may be seen to be plainly wrong just by viewing the colour card attached to Steven's post and his conclusions can only be promoted as infallible (per the ARC discussion) by ignoring that fact. Also, let's remember that the "Sky Grey theory" originally based on a supposed misunderstanding of British requirements for Sky, facilitated by the fact that at that time the appearance of Du Pont 71-021 was unknown, has now been debunked, not least by Dana Bell's own publication on US Export Colors of WWII showing various US factory paint diagrams specifying "duck egg blue"! Having been debunked the theorists then shifted their position to the proposition that specifications were not followed in practice. Ah, how convenient - so that's how those light gray hues come back into the equation again!

Is the paint colour listed and shown on the colour card as 71-021 a light grey? And if we are to disregard colour reproduction as unreliable then surely that must apply to the colour photographs that some of these light gray conclusions have been based on, mustn't it? It strikes me that the ARC discussion is more about (some) people who have made their minds up that the paint colour was light grey and are sticking to that idea come Hell or high water - in which case factual "documents and specs" are as irrelevant as Steven suggests them to be - rather than in any spirit of truly open-minded research.

If Steven's own doubts about "documents and specs" extend to the actual Du Pont paint swatch supplied by Curtiss to the DTD and thence to Hamble as well as the 1942 Du Pont colour card which both lists and shows the paint colour 71-021 (as attached to his post) then we really are in a pickle. In that case I wonder how it is feasible for him to post with such certainty, confidence and regularity about Luftwaffe colours based on available charts and swatches? Surely the same doubts as to whether aircraft were actually painted with any of those colours must apply? But what I think he really means is doubt as to how far - or even whether - this paint colour was applied to the actual aircraft even when specified. Or, perhaps more objectively, whether other approximations or alternatives were also procured, expediently, to meet production needs. That I can agree with - up to a point, but not so far as the anything goes school of thought. However, the identification and matching of those approximations or alternatives to actual colour values is yet another matter and is very imperfectly achieved by using colour photographs, not least because the real paint oxidised and chalked towards a light grey appearance anyway. "Light grey" as a generic in any case covers a lot of ground and this perhaps explains why the various suggested hues of "light greys" for AVG Tomahawks are so diverse.

The Feb 1942 JAC meeting did recommend the use of "a neutral grey" as a generic undersurface paint but it is not clear whether this recommendation was pursued in production runs or whether aircraft finished that way were re-finished before delivery to British and Commonwealth countries. The available archeological evidence suggests answers but cannot be considered definitive due to the limitations of "proof by single example". What the recommendation does make clear is that it was a departure from previous arrangements. There is no indication that it was merely reinforcing an existing practice. It was a fundamental change in policy. This has significance for aircraft manufactured for the RAF before February 1942.

There was probably a delay before this change was implemented on production lines, if it ever was. However, by July 1942 British intransigence over camouflage ensured that JAC had agreed that in future the "British Sky Type S Gray" should become standard, surely a reference to the Du Pont hue. So there was a window of approximately 5 months in which it is feasible that "neutral greys" were procured and applied instead of Sky equivalents. Whether this actually happened and, if so, what they were in terms of colour, remains to be determined. If we accept that it did then a curious question remains over why aircraft finished this way seemed to end up in USAAF service and not in RAF or Commonwealth service. Were export aircraft taken over before finishing and does that explain the lack of RAF serials on some aircraft? But, if so, why were they not just finished in standard Olive Drab over Neutral Grey? There is a missing link in our understanding of how this process worked.

Douglas Bostons

2010-06-21T01:56:00.000-07:00

These colour images are Fox photos from Getty Images. I did try to acquire better copies but the process is . . . er . . . tedious and expensive for digital images not much better than these samples. It is a pity that such historically important images are in the hands of corporate mentalities.

Note the interior and undersurface colour (which ain't gray!) and also the mix of red and grey code letters. The aircraft on the extreme left of the formation shot appears to have a red individual letter but grey squadron codes (wrong! I think it is the prop warning stripe creating this effect). I wonder if the second image shows Fuller TL-8715 Blue (Duck Egg) enamel?

Russian Cobras and Clues

2010-04-22T08:48:00.000-07:00

A little O/T but perhaps a refreshing diversion into the world of the Russian Airacobra, many of which were supplied as ex-RAF aircraft. Russian aircraft colour schemes are not my field so I'm tip-toeing here, but the general impression is given that the majority of ex-RAF Cobras arrived in the Day Fighter scheme (DFS) of Dark Green, Ocean Grey (or mixed grey) and Medium Sea Grey. However the photo above (excuse the poor quality) almost certainly shows aircraft in the original factory applied delivery scheme for the Airacobra which was the Temperate Land Scheme (TLS) of Dark Green, Dark Earth and Sky.

How so from b/w images? Well, the photograph below shows the typical RAF MU re-painting of the Airacobra in DFS. Note that the upper surface colours are applied beneath the tailplane to a demarcation point along the lower fuselage line and that the serial number has been re-painted to the correct style and dimensions. Now return to the heading photos. These show the lower surface colour sweeping up under the tailplane, conforming to the original Bell application and suggesting that these particular aircraft may not have been re-painted before being sent to Russia.

This is hardly surprising as RAF Airacobra contracts were large and it is unlikely that every aircraft arriving in the UK was re-painted before being sent to Russia, especially as the RAF had already rejected the type (unfortunately depriving us of the chance to model RAF Cobras with D-Day stripes or in SEAC colours! Hang on a mo' though . . . . ). The well known photograph below shows either Ivan Bochkov or Efim Krivosheev in front of the latter's Cobra Bort # 16 of the 19 GIAP. The under surface colour sweep up under the tail may just be seen and this aircraft was almost certainly still in the Bell delivery colours of Du Pont Dark Green, Dark Earth and Sky.

The aircraft below shows another detail. The nose stencils on rectangles of the original factory undersurface colour, indicating an early production aircraft with the high demarcation applied by Bell. The stencils were masked off when the RAF MU applied the DFS and filled in the Sky areas on nose and tail with the upper surface colours (also the reason why the camouflage demarcation in these areas on some aircraft is different from the standard scheme).

The photograph below shows one of the Cobras after a mishap but still retaining the RAF applied Sky fuselage band that indicates that this aircraft has been re-painted in DFS.

These photographs sort of vindicate Brian Knight's fondly remembered box art on the Revell 1/72nd scale Airacobra (although it is a 'Q' and he didn't get the under tail demarcation!) and at least gives adventurous modellers the opportunity to finish a Russian Cobra in the TLS with Sky (Du Pont 71-021) undersurfaces! Go on, build one. You know you want to!

AVG Tomahawks - Again!

2010-04-21T05:26:00.000-07:00

I see that the question of the undersurface colour of the AVG Tomahawks is riding the merry-go-round at Hyperscale yet again! In this case the presumption of a light gray and the request for a colour value for it initiated the discussion. That is one of the problems. The "light gray" is not so clearly identified when you peel back the onion skin, so how was it arrived at in the first place?

The origin lies in Terrill Clements' study of AVG colours, quoted elsewhere and re-affirmed by Tom Tullis in his 'Tigers Over China' book (and recently in an article in Model/Military Aircraft Monthly (MAM) which appears to be derived from this). Unfortunately at the time these studies were written the appearance of 71-021 was unknown. Mr Tullis states in his book, and it is repeated in MAM, that "While the RAF used a greenish-blue color called "Sky Type S" for their fighters, there wasn't any DuPont color that closely matched it." This is incorrect. Du Pont 71-021 was designated as "Sky Type S Grey" and was shown in a contemporary Du Pont colour card to be a close match to AM Sky. The Du Pont 71-021 swatch was provided to British contractors responsible for supporting Curtiss P-40 aircraft in the UK via the DTD from Curtiss themselves and is an actual sample of paint. Why some researchers should accept and state that specific Du Pont colours were used on the upper surfaces of the Tomahawks but then vehemently refute that Du Pont's AM Sky equivalent was used on the under surfaces is beyond this writer.

Both authors speculate on the identity of a "light gray" colour from selected colour photographs, then choosing a USN colour 'Aircraft Gray' as the closest (later ANA 512 'Glossy Aircraft Gray' reported to be the same as or similar to FS 16473). The colour photographs used for this identification were stated to be "the best" but it remains uncertain how that criteria was applied. The best at showing a gray rather than something more like Sky? The tendency to "correct" colour photographs also throws up significant imponderables. In terms of established colour science attempting to identify precise colours from the visual assessment of colour photographs is fraught with unreliability. In Mr Tullis' book there are as many colour photographs of AVG Tomahawks showing colours that appear to resemble AM Sky as there are that are that appear to show grey - if not more. Both authors appear to have ignored the probability of the paint surface oxidising and "chalking" in the tropical environment to appear more greyish to the eye.

Again it is worth emphasising that light gray was the anomaly, the deviation; the AM wanted Sky, the factory drawings specified 71-021 (or "duck egg blue"). And apparently apart from those aircraft delivered to the AVG all the other Tomahawks arrived in under surface colours which were not remarked on at the time as being different or incorrect to specification, but rather were described by contemporary observers as "duck egg green" and in at least one RAF Squadron ORB as "grey green". So there should be pretty robust grounds for determining that a light gray was applied instead. Are there?

The White Ensign Models Colourcoats paint WEMCC US03 for the USN Navy colour 5L Light Grey has been cited in comments here as a good match for Du Pont 71-021 and a Floquil hobby paint of this colour is also recommended by Bruce Archer at Hyperscale. Bruce assets that "a Lt grey, similar to the FAA's 'Sky Grey'" was the colour applied to the undersides of the AVG Tomahawks but again provides no compelling evidence for this statement.

Steven Eisenmann asserts that the underside colour "definately (sic) was not Sky as we know it, probably anywhere from a light gray to a bluish gray. Who ever got them the paint the cheapest." That use of "definitely" makes it a bold statement but logic also suggests that, unless Steven was standing notebook in hand as each Tomahawk rolled out of the paint shop, that the "cheapest" paint may equally have been more like the required Sky than light gray. The proposition that anything went, that Curtiss were able to procure any old paint for the RAF order must, if accepted, raise as much doubt about the result being a light gray as anything else. Again the evidence for this statement is not provided but perhaps depends on the Curtiss paint contract records mentioned in posts by Bruce (which identify paint names from other suppliers including reference to "grays") but so far unpublished (and without any identified or matched colour values). AFAIK these records have not been cross-referenced to a specific chronology, dates or production batch serials.

The unequivocacy of these statements and the determination to make very firm conclusions about the appearance of colour from digital images of colour photographs is intriguing. The use of Du Pont 71-021 has come under robust challenge - quite rightly, as peer review and critique is an integral stage of any serious research - but it is perplexing that the same rigourous challenge has not been applied to the "Sky Gray Theory"; some of the proponents of the theory appear to be unaware of this double standard or choose to ignore it. Why is that? Is it perhaps a case of the man being played rather than the ball?

I haven't checked out the Floquil or White Ensign Models Colourcoats paints for this colour but I was able to get some more information about the appearance of 5L from http://www.steelnavy.com/usnchips. There it is identified as being the light blue-grey of Munsell 10 B 7/1.5 whereas Du Pont 71-021 is closer to 10 GY 8/1. The DE2000 difference calculation between these colours is a significant 11.7 where a calculation of 2.0 or less is the equivalent to a close match. Viewed in juxtaposition to the 5L colour 71-021 looks even closer to the required and specified Sky. I'm not about to write a multi-page treatise here on metamerism but those sufficiently interested can explore the phenomenum via Google and there are also numerous demonstrations online to show that what we think we are seeing we are not!

The Steel Navy site also mentions that the approximate FS 595B equivalent to 5L is 36320, but the DE2000 calculation for the Munsell value to FS value difference is 8.25 (the author does note that the FS numbers are estimates based on his [visual] comparison of color chips to FS chips). The closest FS equivalent to 71-021 is actually 25622 @ 1.50 (so it is very close). Steven seems determined to assess 71-021 as a "bluish gray" even though he has never seen the actual paint. In colour value terms it is not a "bluish gray" but rather a paler, slightly more blue version of AM Sky (the clue is in the Munsell designator GY = Green Yellow!), although Steven's visual perception is quite understandable as one amongst many possible perceptions. Some people describe the colour as a pale green, others as a pale blue or blue-grey and some just see grey. But visual perception and assessment of colour are not the same as colour science or the identification of the colour values by measurement.

The closest FS 595B equivalent to the 5L Munsell value is actually FS 36375, but not very close @ 3.95 and darker and greyer than the bluish-grey of that value. FS 36473 is further away @ 5.67. In comparison to 71-021 the appearance of FS 36473 is significantly darker and greyer @ 10.4 and compared to FS 25622 even further away @ 11.5. Assuming Steel Navy's identification of 5L is correct those who may believe that 5L and FS 36473 are interchangeable as Tomahawk under surface colours are plain wrong, even before we consider 71-021, so what does that say about the theory?

Although this preliminary exploration of the colours suggests that 5L is not the same or even a similiar colour as 71-021 and/or FS 36473, the hobby paints for 5L may be closer. I shall check those out in due course.

Corsair Confusions

2010-03-17T01:14:00.000-07:00

These colour photographs of FAA Corsairs clearly show the ANA 602 "light gray" applied as an undersurface paint colour instead of ANA 610 Sky. I know that it looks more like ANA 610 Sky, which was the required FAA finish for the Temperate Sea Scheme, but you need to "correct" the images using Photoshop until they appear as the correct "light gray" to conform to the hypothesis that "light gray" was applied instead of Sky.

Seriously though, even the third "corrected" image can't quite eliminate the evidence of Sky in favour of "light gray". In the top very high quality image note particularly the colours of the fuselage roundel.

ANA 610 Sky was retained in ANA Spec AN-1-9 Bulletins 157 and 166 until the end of the war, in fact re-affirmed in a Jan 19 1944 amendment that it would be accepted as standard, whilst ANA 602 was dropped at the same time.

(Really funny, but one of these images "corrected" to show "light gray" was recently posted on a well known forum as "proof" that FAA Corsairs were "light gray" underneath and not Sky. Surely the path is very long and very winding in that particular garden and many are being led up it!)

Image credits: From the internet and author's collection - un-"corrected".

Contracts and Colours

2009-09-29T01:27:00.000-07:00

It is a great pleasure and a privilege to introduce this first guest article to 'American Aircraft for the RAF'. David Muir, the author of the superlative 'Southern Cross Mustangs', describes the quality control, testing and acceptance framework and methodologies used in the preparation and painting of aircraft manufactured in the USA for the RAF.

CONTRACTS and COLOURS

Before the RAF expansion programmes of the late 1930s the British and American military aircraft industries had significantly different approaches to the philosophy and management of their contracts with the client services. American manufacturers were largely responsible for quality control of their own output and warranted their products to the users on the basis that any faulty or defective product would be replaced at the manufacturer’s cost. Any involvement of the clients in quality matters tended to occur toward the end of the process as the aircraft were delivered and they were generally accepted on the signature of the firm’s Chief Inspector.

In contrast the Air Ministry (AM) – the main British procurement agency - had highly developed design requirements and regulations that controlled and monitored manufacturing throughout the process from basic materials through to the acceptance of the aircraft into service. The Ministry’s aim was partly to minimise defects during manufacture but more importantly in the field where manufacturing defects directly affected operations. In the UK the entire process was conducted by teams of Aeronautical Inspection Directorate (AID) staff who were located with a Resident Technical Officer (RTO) appointed by the Directorate of Technical Development (DTD) and a Test Pilot at each contractor’s factory and/or shared between a number of sub-contractors.

Central to the Ministry’s philosophy were the concepts of interchangeability and traceability. The AID Inspectors used gauges, special fittings and other measuring tools to check parts, components and assemblies to ensure that they conformed to the contract requirements and correctly mated with the counterparts to which they were to be fitted. An AID inspector’s approval (in the form of his unique symbol rubber stamped in ink on or steel stamped into) each item before it could be used in any subsequent stage of the production line. Each step between the original material and the finished and test flown aircraft was thus checked and the results documented to form a continuous record that allowed any defect to be traced back to its source.

In June 1938 when the British Air Mission placed the first orders (with Lockheed for Hudsons and North American Aviation for Harvards) it used contracts that closely followed AM requirements and practices. By July 12 two AID staff, a DTD RTO and a Test Pilot had arrived in Los Angeles to monitor the lines at Burbank and Inglewood. Despite the differences between the two engineering cultures – eg at first parts of the Harvard were not interchangeable between airframes – NAA recognised the advantages of the AID system and quickly adapted and incorporated changes to its tooling and methods.

With only one AID examiner at each factory, the LA based inspection process was largely delegated to the contractor’s staff with the examiners directly involved at only a few key points in the process. Nonetheless the British procedures largely prevailed with the documentation for each aircraft ultimately being signed off on AID Form 827 by the contractor’s Chief Inspector before being countersigned by the AID Inspector in Charge. These so called Inspection Reports stayed with the aircraft after being accepted by the RAF and were shipped to the UK for storage.

The same system continued after the BAM became the British Supply Board (BSB) within the British Purchasing Commission (BPC, November 1939) and later the British Air Commission (BAC, July 1940). BAC’s AID staff would prepare Critical Reports on new aircraft and modifications which passed to the RTO (A) and through him to the contracting firm (known as the Design Authority) for remedial action. The role is neatly summarised in the following extract from BAC correspondence with its staff in the factories:

…it is well that we should bear in mind the Order, the Drawing, and the Component. It is our function to see that the BAC get what it wants and the Contractual Requirement, the Technical Requirement and the Article supplied are the three elements of inspection.

NAA wholeheartedly embraced the underlying philosophy of the AM process. Thanks to the relationships established during the Harvard contract NAA’s design team were able to discuss AM design requirements and practices with the BPC staff during the early concept stages of the NA-50B design. Thus British principles of interchangeability and quality control were incorporated from the outset in the resulting NA-73 design purchased by the RAF as the Mustang.

Following the establishment of the Lend Lease programme all new aircraft manufacturing contracts were placed by the American Army and Navy and from August 1940 were coordinated by the Army-Navy-BPC Joint Committee which later became the Joint Aircraft Committee or JAC. In early 1942 this responsibility passed over to the Munitions Agreement Committee (Air) (MAC (Air)) which was part of the Committees of Combined Munitions Agreement Board.

The new arrangements under Lend Lease meant that the AID inspectors had no contractual role as such. However, on behalf of the Air Ministry they remained responsible for monitoring the effectiveness of the contractor’s inspection system and its staff, the documentation delivered with the aircraft, the allocation of RAF serials as well as the quality and contract conformity of the delivered products allocated to Britain and the Commonwealth. Their expertise was also sought to help solve construction quality problems in some largely or exclusively American programmes such as the B-24 and B-29, both of which initially had serious interchangeability difficulties.

NAA continued to manufacture Mustangs under lend Lease using the same quality control procedures established on the Harvard and early Mustang production. Damaged or defective parts or assemblies were still identified and a decision made by an Inspector as to the acceptance, reworking or scrapping of that item. Any significant deviation from the order/requirement/drawing/specification needed a formal Air Ministry Concession and was recorded in each aircraft’s documentation.

As with any other component Air Ministry Orders and DTD Technical Circulars set out the customer requirements for camouflage, markings and stencils and NAA specifications, drawings and diagrams describing them in detail were included in the contract between the parties. For example AMO A.664/42, DTD 83, DTD 360 and Air Diagrams 1160 and 2001 established the camouflage and insignia requirements for the RAF’s single seat fighters.

Their contents were incorporated into the NAA contracts in diagrams such as Diagram 99-20-23A (used as 956a (US) and 956b (RAF) of NAA Manual NA 5724) for the B/C/Mk III Mustangs and NAA Diagram 109-00-286/Figure 468 and drawings 102-00010 and 106-00010 for the later D/K/Mk IV/IVA variants. Careful reading of these documents reveals that changes were made, documented and implemented to the camouflage colours in the period when the RAF Mk 1s and Mk IIIs. For example Dark Olive Drab replaced Dark green on the early Mk IIIs.

For the Air Ministry and the RAF camouflage and marking of the aircraft was an important element of operational readiness. Just how important is demonstrated by the Air Ministry’s willingness to expend the time, resources, manpower and money needed to repaint earlier deliveries when the role of the Mustang was reclassified from army cooperation to fighter, thereby changing its camouflage requirements from the Temperate Land Scheme’s (TLS) green and brown to the Day Fighter Scheme’s (DFS) green and grey.

Given NAA’s well established inspection process and culture it is difficult to see the company or its staff even attempting to make unauthorised changes to the camouflage colours used on the RAF Mustangs. In order to be approved any such variation in the colour would have to have been small – i.e. essentially indistinguishable from the approved paint samples held by the AID team.

Any unauthorised larger variations (eg replacing RAF Sky with US Light Gray) would inevitably have been picked up down the line and risked having the aircraft rejected and/or sent back for reworking during the final acceptance process. Similarly it is likely that any request for an Air Ministry Concession to cover a variation that meant parts had to be repainted before they were used on another airframe would not have been approved by the AID team as it directly reduced interchangeability and would have necessitated unnecessary work by the RAF in the field.

In this context the hypothesis that American manufacturers were largely free to make whatever changes and substitutions they deemed necessary without regard to their contractual obligations or their British customer’s needs is clearly not credible. The idea that NAA unilaterally substituted an unidentified and noticeably different gray for the specified and contracted Sky Type S undersides on the RAF Mk IIIs is easily refuted by NAA’s own documentation. As late as the beginning of November 1943 NAA’s publications called for Sky Type S – not gray – on the B/C/Mk IIIs…just as it had contracted for, documented and used on all the Mustangs it had built up to that date.

Shortly thereafter the entire scheme changed from the TLS to the DFS - but that is a story for another day…

David Muir

The following books provide excellent coverage of the Anglo American aircraft programmes during World War 2; both are highly recommended for anyone interested in reading further.

‘The British Air Commission and Lend Lease’ compiled by K. J. Meekcoms (Air-Britain, Tunbridge Wells, 2000 ISBN 0 85130 291 2) covers the inspection and contract administration in detail.

‘Air Arsenal North America, Aircraft for the Allies 1938-1945, Purchases and Lend-Lease’ by Phil Butler and Dan Hagedorn (Midland Publishing, Hinkley, 2004 ISBN 1 85780 163 6) covers the individual aircraft in slightly greater depth.

15th September 1940

2009-09-15T03:03:00.000-07:00

Battle of Britain Day.

In remembrance of all the pilots and servicemen of all nationalities who fought to defend this island in 1940 and so ensure the ultimate defeat of the Nazi regime.

Allison Engines

2009-09-14T03:16:00.000-07:00

This colour advertisement and photograph of an Allison engine may be useful for those planning to detail the engine compartments of models. The photograph is of a running display Allison 11710-115 V12 engine at the Classic Jets Fighter Museum, Parafield airport, Adelaide, South Australia. It also shows the appearance of the exhaust stacks.

Southern Cross Mustangs

2009-09-07T05:20:00.000-07:00

A book review I read recently described this as an age where "opinion triumphs over knowledge" and I have certainly found that to be true in the field of aircraft modelling. A little off-topic for AmAir4RAF but the publication of David Muir's superlative study 'Southern Cross Mustangs' represents such an excellent, rare and outstanding example of knowledge triumphing over opinion that it needed to be featured here for those who may have missed it.

Southern Cross Mustangs began life as a small article for a modeller’s magazine about the target towing Mustangs operated by Illawarra Flying Services out of Sydney in the 1970s. David began searching for information about these unusual and colourful aircraft little realising that it would become a decade long quest. His project grew ; firstly to include the other civilian operated Australian Mustangs, then their New Zealand cousins and then, in order to understand their initial civilian markings, the RAAF and RNZAF fleets. This in turn led to including the Mustangs operated by the RAAF in Italy at the end of the Second World War.

Over the years David's search for information spread far and wide. The National Archives of Australia branches in Adelaide, Canberra, Perth and Sydney, Archives NZ and the service museums in both countries were consulted along with a number of private collections. One of the most satisfying aspects of the research was meeting with the original pilots and hearing their stories and recollections of operating the Mustang in peacetime and at war. Additional help came from Mustang enthusiasts around the world; apart from the many Australian contributors, material was provided by historians in the US, Canada, Italy, the UK, Switzerland and New Zealand. As David notes in SCM he was constantly surprised by the amount and quality of the material held by modellers and historians everywhere and very grateful for the generosity with which they shared their information.

After a decade of research, Southern Cross Mustangs was transformed into a 100,000 word 460 page masterwork. With 17 chapters covering different aspects of the Mustang story it has 600 profile views covering the known marking and equipment variations, over 490 photographs and reproductions of contemporary documents and over 275 plan and detail drawings prepared especially for the book to illustrate details such as equipment, markings and modifications. It is, quite simply, a breathtaking achievement of the most diligent and painstaking research and a perfect model of how an aircraft monograph should be presented.

Aimed squarely at the enthusiast, modeller and historian, Southern Cross Mustangs is without question the most thorough examination yet undertaken into the history, technology, camouflage and markings of the Australian and New Zealand Mustangs.

Of great relevance to AmAir4RAF is Fig.692-b from NA Report 5724 Structural Repair Manual reproduced here with David's kind permission. It shows quite clearly the factory paint colours as of November 1943 and may be compared to the colour photograph posted earlier. No doubt the clamour of opinion will do its best to triumph over this pure gold nugget of knowledge but for those who have open minds and eyes that can see it will be of exceptional interest.

David writes that between November 1943 and April 1944 the delivery scheme changed to Day Fighter - OD 613, Sea Gray 603, Light Gray 602 with spinners as Sky 610 (described as Sky Blue 610 in Fig.468 - British Camouflage Color Scheme [Drawing 109-00-268] from the April 1944 NAA Erection and Maintenance Manual and Structural Repair Manual AN-O-60-3). The Sky fuselage bands do not appear on these drawings so presumably were not part of the delivery scheme and were added by modification centres or MUs.

Prior to this the RAF Mk IIIs were delivered in Temperate Land - Olive Drab, Dark Earth and Sky - Type S (as per Fig. 692b from NA Report 5724 Structural Repair Manual, November 1943). The exact point of change on the production lines is unknown.

For anyone interested in RAAF or RNZAF Mustangs - or even RAF Mustangs - this book is a gold mine and is very highly recommended. Southern Cross Mustangs is not inexpensive but then real quality and craftsmanship never is. It may obtained here from Red Roo Models whose reliability and service I can also unhesitatingly recommend.

P-40E Mysteries ~ Part One

2009-08-19T03:07:00.000-07:00

Much has been written and published about early P-40E colour schemes in specialist modelling journals but unfortunately some of it has relied on speculative hypotheses and given root to enduring characterisations of paint colours which have become almost modelling conventions. Linking the chronology of colour scheme instructions, production dates and the exigencies of the war situation is often omitted and writers tend to tackle them in isolation. Making these connections is an essential preliminary to better understanding of the schemes and how they evolved.

Production Pressures

Throughout the war aircraft manufacturers were under intense pressure to produce machines in quantity and at speed, resulting in both expediency and improvisation. Production could not stop just because paint to the exact specification was unavailable and paint supply was unlikely to remain constant to the needs of production, or perhaps more importantly destination. Added to these exigencies of wartime production and supply were the human failings attributable to misinterpretation or misunderstanding of official directives and instructions.

Pressure on Curtiss

In early 1942, at a time when the Japanese army and navy threatened both India and Australia, Curtiss was having to produce sufficient P-40's to meet the demands of several users in at least two theatres of war, the Middle East and the Far East. Destinations for the supply and replacement of P-40 aircraft altered rapidly and at short notice with the changing fortunes of war. Losses occurred during supply also had to be made up, often by diverting unsuitably painted aircraft from one theatre to another.

For example in February 1942, following heavy combat losses of P-40s in the Phillipines and Java, 25 crated replacement P-40s had to be abandoned to the Japanese at Tjilatjap and 32 more were lost when the USS Langley was sunk. These two losses alone represented 3.8% of P-40E1 production. Ir was a time of great danger and uncertainty for the Allies.

The P-40 was at that time the best fighter available in quantity to the USAAC and despite being maligned since by some aviation writers was in fact a reliable, rugged and well-armed aircraft, versatile in its roles that was able to challenge and even deny air superiority to the Japanese until more advanced designs appeared with which to turn the tide. In the hands of both the USAAC and RAAF it was crucial to the successful defence of Northern Australia and its contribution to the air campaign in China far exceeded the number of aircraft actually deployed. In the Middle East as the Kittyhawk it became synonimous with successful fighter-bomber sorties harrying Axis ground forces across North Africa and eventually in Italy.

To Curtiss at that crucial time official paint directives were probably a nicety, adhered to wherever possible but only as closely as paint supplies and production priorities allowed. However, even the official position was changing, both pragmatically to accommodate the realities of production in adversity and intentionally to ease future production complexities for multi-service, multi-destination demands. As wartime losses and the diversity of war fronts struck home it began to be realised that the original concept of painting aircraft to match the requirements of a specific environment were no longer practical or even feasible.

Enter the Joint Aircraft Committee, formed in September 1940 to co-ordinate aircraft production for the US Army, US Navy and Britain . .

To be continued . . .

Blue Skies and Duck Eggs

2009-08-14T06:52:00.000-07:00

Although of indirect relevance to the main interest of this blog it may be worth re-visiting the subject of the Sky paint colour and particularly its chronology. Much of the focus of discussion - and recent reference books - naturally, has been on its adoption by Fighter Command and the confusion caused within that Command as to the appearance of the new colour. Paul Lucas, in 'The Battle For Britain - RAF May to December 1940' (Camouflage & Markings No.2, Guideline Publications, 2000) plots the introduction of the colour and puts forward an argument, based on extant paint samples, for the use of ready matched British Standard alternatives prior to the availability of adequate stocks of Sky paint.

Re-visiting earlier references, which may have been forgotten or become unavailable to modern enthusiasts, is always worthwhile and it is rash to dismiss all of them as obsolete or outdated. In 'Bombing Colours 1937-1973' (PSL, 1973) author Michael J F Bowyer, making much use of wartime notes as an eyewitness observer, describes the origin of the colour as a proprietory paint 'Camotint' produced by Titanine Ltd. It was first applied to specially painted Blenheims of 114 and 139 Squadrons as 'light sea green' in November, 1939, not appearing widely on the undersurfaces of this type until February 1940 when it was being described as "Duck Egg Green". Mr Bowyer quotes Titanine's own account:-

"The colour Sky originated just prior to the war from a shade devised by Titanine and called 'Camotint'. This was a greenish blue shade, "Type S" referred to a standard of finish. At the start of the war matt camouflage paints were very rough and as speeds of aircraft increased, it was found that significant advantages in drag could be obtained by using smoother finishes while retaining an adequately non-reflecting surface. "S" thus stood for "smooth"."

The company went on to describe the formula for this paint:-

"The SBOAC formulation in use during the war consisted of White tinted with about 4% Yellow Oxide and a trace of Prussian Blue. The white pigment varied with the type of paint - NC (nitro-cellulose) paints used Zinc Oxide while Synthetic Resin paints used Titanium Dioxide, Antimony Oxide and some Zinc Oxide."

Note the imprecision of the formula which is entirely consistent with the variations in appearance of Sky observed throughout the war.

On 21 November 1939 the Royal Aircraft Establishment (RAE) recorded the receipt of a sample of 'Camotint gloss lacqueur' from Cellon Ltd, presumably a Cellon manufactured version of the Titanine paint. The RAE were requested to produce sufficient "smooth-finish, none-gloss" paints in Dark Green, Dark Earth and 'duck egg green' colours to finish three Blenheims and sufficient 'duck egg green' to complete one Spitfire of the Photographic Development Unit (PDU).

Mr Bowyer makes an interesting distinction in his sister book 'Fighting Colours 1937-1975' (PSL, 1969) over the terms "Sky" and "Duck Egg Green" (my emphasis):-

"Throughout this book some attempt has been made to differentiate between fighters with 'Sky' undersides and those with the deeper shade here described as 'duck egg green'; the original official title 'Sky' was a generic term for some light shades developed in 1939. Light sea green was the shade chosen for use on bombers and fighters, re-named duck egg green - which is a better appelation than duck egg blue. Lighter shades are referred to as Sky in this book. These were in evidence by 1941 and eventually a very pale shade was used by late 1943. A possible explanation for the darker shades is that they were the result of mixes by RAF units, whereas the pale shades originated at the manufacturers. Darker shades were usually worn by the bombers of 2 Group whose Bostons* and Venturas with the pale Sky shades looked most conspicuous."

* See photograph of Boston in US equivalent Sky above.

The confusion over Sky in Fighter Command during the late summer of 1940 has been well documented and the subject of alternative interim paints is beyond the scope of this article. What is relevant, however, is the subsequent clarifying Air Ministry signal sent to all commands on 7 June 1940 and which read as follows:-

". . .the colour of camouflage Sky Type S, repeat S, may be described as Duck Egg Blueish Green."

Note the emphasis on 'S' which may explain why the 'Type S' suffix has been uniquely associated with Sky (even though it was equally applicable to other smooth, matt paints) ever since.

Thus whilst there may have been confusion about this colour within Fighter Command, exacerbated to no small degree by the shortage of actual Sky paint, by the middle of the year 1940 a description of the colour as "duck egg blueish green" was to become common currency and make its way across the Atlantic via the BAC to be communicated to American aircraft manufacturers. US factory drawings of several types indicate the painting of undersurfaces to be "Duck Egg Blue" and in at least two cases this colour was directly correlated to Du Pont 71-021 Sky-Type S Grey.

The term "Camouflage Duck Egg Blueish-Green" lasted long enough in North America to also appear on the Canadian Titanine Ltd paint chart in 1941, without mention of Sky (see pic above).

Finally, on the subject of variations in the appearance of Sky are the observations of South African eyewitness and expert aviation artist Ron Belling ('A Portrait of Military Aviation in South Africa', Midland Counties, 1989):-

"The underside Sky (of a Corsair) also lost some of its initial cleanness to take on the appearance of a pale dirty grey.";

"In additional the tonal weakness of the Yellow constituent (of Sky) was easily broken down by ultra-violet light, whereas the other pigments remained more intact, in the form of a pale, dirty grey with a hint of Sky".;

"Unaffected Sky, removed from a Fairey Swordfish (HS256), matches the current BS 210, wartime Sky and FS Sky. Seen together with a piece of underside skinning from a Kittyhawk (No.5106) which was also finished in FS Sky (a rarity among SAAF Kittyhawks) both conform to official standards, thus proving that the original colours were of a high production standard."; and

"Their (Hawker Furies) Sky undersides were a true representation of the official colour, with no fading or discolouration, and were nothing like the washed-out hues seen during the war."

Ragged, de-bagged and thoroughly discombobulated

2009-08-13T02:51:00.000-07:00

An extraordinary thread at you know where on the subject of P-400 colours got yours truly into trouble with the Sky Grey Clique. The authoritative Dana Bell contributed and made some curious statements about the subject which we will be examining in detail later. Hyperscale's resident serious color researcher quickly demolished my preposterous and innocent reply to the original request for information so it is worth reiterating the extent of the poverty of my research - which according to another leading collector of bits of old metal is neither factual nor original. Basically, where my "conjecture" falls short is as follows:-

1. The original wartime Du Pont 71-series colour card is just a "wish list" and can be discounted.

2. "My" 71-021 color "chip" (actually the rendering of the measured colour value from an actual and original 71-021 paint sample sent to the DTD by Curtiss) proves nothing even though it is almost exactly similar to the colour card chip.

3. The Bell factory paint shop drawing 14-976-002 of 1/10/40 specifying the use of 71-021 and identifying it as Sky-Type S Grey proves nothing. Bell could have used some other colour in production, not made by or matched by Du Pont and which was a light grey rather than the Sky or Sky equivalent required by the BPC/BAC, AM and RAF.

4. Eyewitness reports describing the colour seen on RAF Airacobras as "duck egg green" or "similar to RAF colours" may be discounted as unreliable; and

5. Colour photographs which appear to show a colour similar to 71-021 may be discounted as unreliable.

So this leaves us . . . where, exactly? With a hypothesis that an unidentified light grey may have been applied instead but apparently without tangible or documentary evidence to support that other than a sweeping generalisation that "US production practice was not as rigorous as British", etc.. Does anyone actually have a sample of this light gray? What is it based on?

The nuances of the argument, as opposed to its facts, are, it seems, not to be addressed in any objective way. We still do not know the basis for believing that 71-021 was originally matched to Sky Grey (and perhaps later changed) when the factory drawings state "Duck Egg Blue". The logical weaknesses of the Sky Grey hypothesis do not apparently prevent attempts to knock holes in the alternative. The attention is unfortunately on that and requests for evidence of Sky grey are ignored or disregarded. Perhaps the comfort zone is vague speculation that seeks to be authoritative by a presumption?

Apparently without possessing the actual documents proving what paint was purchased and actually used in production the rest is meaningless. Presumably an actual sample of the wet paint is necessary to preclude all doubt about its characteristics and some form of proof that it was actually applied and not something else instead. These stringent requirements, however, do not seem to apply to other pronouncements on color. No such doubts about the various Luftwaffe "farbtons" it seems, where reqs, specs and color cards are perfectly adequate as evidence.

Seriously, folks, what a crock of utter shite. It seems one only has to contribute to the subject of colour on certain "trigger-word" aircraft at a certain forum to be "pounced on" and defenestrated, so to speak.

Fairies at The Bottom of the Garden . . .

2009-07-17T04:08:00.001-07:00

. . . and you get there by being led up the garden path.

In respect of the Bell factory finish for the undersurface of RAF Airacobras the serious color expert pronounces thus:-

"It is arguably anywhere from a light Gray to a Bluish-Greenish Gray. But it is not Sky"

What nonsense. The evidence for Sky equivalents and the Du Pont substitutes have been presented here and here. Where is the evidence for a "light Gray" (sic)? Well, where is it then?

Oh, yes, of course. Bell, like other American manufacturers completely ignored the requirements of their customers and their own factory paint specifications and used any old colour which they could get hold of cheaply - which happened to be a light grey. But where is the evidence for that opinion or belief ?

Funny that the same scepticism about user requirements, factory specs and the appearance of paint swatches not being followed by manufacturers doesn't apply to "Farbton 79" or the other little hobby horses isn't it?

The corrected colour photograph of the Airacobra in New Caledonia (not Guadalcanal) posted by Ben P (and reproduced above - well done Ben) looks remarkably like the swatch for Du Pont 71-021, which paint was specified by Bell and which paint was called "Sky Type S Grey". At the time the RAF who were buying the aircraft also required Sky undersurfaces.

Not Sky? Pull the other one.

RAF Style Camouflage on the Mustang

2009-05-14T01:14:00.000-07:00

This image, scanned from a first generation colour print, shows very well the US equivalent of Sky on the undersurfaces of a Mustang. Formatting and reproducing this image online gradually reduces this colour, so apparent on the original print, to a pale grey. I wish I could show you the original colour slide and print.

Numerous images of the same or similar Mustang have appeared online, with undersurfaces which appear to be a "light grey". Don't be fooled. The nuances from a pale blue-green to a pale grey are slight and easily accounted for by scanning, formatting, reproduction, imaging and viewing software and monitor calibration. The appearance of these colour photographs has spawned an idea that light grey rather than equivalents for AM Sky were applied to US aircraft being manufactured for the RAF. The online pundits who peddled this idea and authored numerous "authoritative" articles to promote it now have a vested interest in suppressing evidence which suggests the paints used were actually much closer to the MAP requirements and certainly not light greys. They have moved from a position of stating that US manufacturers were confused and misunderstood RAF requirements for Sky as being Sky Grey (now thoroughly discredited by the evidence) to a position where US manufacturing laxity allowed expedient choices of paint supply where light grey was chosen instead. Some of these articles contain definitive statements about the paints and colours used which are simply not borne out by the documentary, photographic and archeological evidence. As this blog continues, believe me, the evidence will grow.

One of the most disappointing outcomes of this modern "research" is to see model companies, decal manufacturers, profile illustrators and now even paint manufacturers persistently repeat and promote the idea of light grey, and nothing but light grey, on the undersurfaces of these US export aircraft for the RAF.

Examine the image in large size by clicking on it and then compare and contrast the undersurface with the cool, neutral grey of the P-51 in the background. The difference is even more pronounced on the original print where the blue-green cast is much stronger. Then compare and contrast the undersurface colour to the Du Pont 71-021 swatch reproduced below.

Also, compare and contrast the "Dark Green" of the camouflage on the foreground Mustang with the Olive Drab on the P-51 in the background.

Early P-40 Colours

2009-05-13T06:47:00.000-07:00

Although the value of colour photographs in determining colour is questionable this one makes for an interesting "compare and contrast" exercise with the colour chips for Sky Grey, Du Pont 71-021 and Sky. As may be seen Sky Grey is a cold, neutral grey when compared to 71-021 and Sky.

In August 2001 AVG camouflage and markings expert Terrill Clements made the following comment at the Flying Tigers AVG forum:-

"The factory paint job was brown and green on the top, and the bottoms were light gray with a greenish/blue cast. All the evidence I have seen indicates that this was indeed the colour scheme of the Tomahawks supplied to the AVG. (There were likely a few slight one-off exceptions as Curtiss put together the shipments with the components at hand). As you indicate, the planes were in most cases from the same production lines. I won't go into the tedious details, but the colors used were Curtiss' attempt to match the colors specified for RAF Day Fighters in 1940-41, but NOT exact matches."

His subsequent books differ in describing the colour only as "light gray" although one of them IIRC mentions the blueish cast. Mr Clements had responded to the following post by another member of that forum:-

"Although I cannot vouch for the H81 aircraft sent to China, I do have information on the H81 aircraft that went to the RAF Sqdns in the Desert. The aircraft delivered in the Desert were originally painted Brown and Green with a grey-ish green colour underneath (hard to work out if grey or a close match to duckegg green). This is mentioned in Sqdn ORB's (Operational Record Books)."

This post went on to explain that some of the serial numbers involved were to either side of some of those sent to Burma, so it would have been unlikely that they were not painted identically at the factory.

My uncle Frank, who during the war fitted British radio equipment into these early Tomahawks, was always adamant that they were painted in very similar colours to British aircraft and that the undersurfaces were not light grey but a colour very similar to RAF Sky. My impression of his recollection is strong because at the time of our discussion I held the view that they were in a non-standard colour like a light grey. The extant documentary and physical evidence subsequently persuaded me that the paints used were in fact very similar to the RAF requirements - although not exactly so - just as he had described them.

Many other eyewitnesses in Britain described Sky and Duck Egg Green on the undersurfaces of the P-40's and not light grey.

There is an interesting analysis of the colours here, by Rato Marczak. Whilst not wholly concurring with Mr Marczak's conclusions, made in the absence of precise information about the Du Pont 71-021 colour swatch and card, his analysis is meticulous and has great merit. The corrected colour image of AVG P-40 # 49 in flight is interesting in that whilst the undersurface colour does not look particularly close to the FS 36622 value identified by him as the probable colour of 71-021, it makes a useful comparison to RAF Sky!

Two Du Pont Dark Earths?

2009-04-19T05:17:00.001-07:00

One of the enduring mysteries of Curtiss P-40 production for the RAF is why two versions of the Du Pont 'Dark Earth' were used. A "sandy" 'Dark Earth' 71-009, and a darker paint, 71-035, closer in appearance to the AM colour.

The 1942 Du Pont colour card, which shows the 24 '71 Line' Colours matched to the MAP (Ministry of Aircraft Production) Colour Standards, does not include 71-009 but it has to be noted that 'Light Earth' 71-048 is very similar in appearance to that colour!

The importance of this colour card in conveying British colour requirements to US manufacturers was revealed by Dana Bell.

Incidentally, we know that Du Pont 71-009 'Dark Earth' is the correct nomenclature because the paint is specifically mentioned in a 1943 NACA report as being applied to a Glenn L Martin airfoil section.

Sky Grey theorists may also wish to note that the colour card does not include 'Sky Grey', nor any colour which is matched to "aircraft gray".

Note also that MAP specified a colour matched to Du Pont 'Cockpit Light Green' 71-036 for the interior paints to be used on aircraft constructed for the RAF.

Airacobra Cobblers

2009-04-17T03:15:00.000-07:00

Yesterday I read a forum post where a "serious colour researcher" suggested there are two "points of view" about Airacobra/P-400 undersurface colours. Well, the "point of view" of this author is based on the following evidence:-

1. The extant Bell factory drawings and notes for production specify the use of Du Pont 71-021 Sky Type S Grey for the undersurface colour on aircraft constructed for the RAF.

2. The MAP Du Pont colour card "Du Pont 71 Line Colors to Match Ministry of Aircraft Production Colour Standards" includes a painted (not printed) chip for 71-021. It is not similar in any way to AM Sky Grey or "aircraft grey". It is closer to AM Sky. This extant document is the one referred to in the quote below from Dana Bell. It was cited by MAP as a convenient reference for matching RAF colour requirements by other US paint manufacturers. The Du Pont colours were, in effect, match samples, and we know exactly what they looked like.

3. The extant measured swatch for 71-021 is not at all similar to AM Sky Grey or "aircraft gray". It is a pale Duck Egg Blue colour. It is more of a pale blue-green than the colour card chip, which is closer to AM Sky.

4. The Bell Aircraft factory drawing # 14-976-002 issued on 1/10/40 (and subsequent revisions) specify the use of Du Pont 71-021 for the undersurfaces of RAF Airacobras throughout the production run.

5. In respect of the Airacobra AH573 tested at the A&AEE the extant documentation refers to the high quality of the paint and its application and how well it matched the RAF colours required.

6. A series of colour photographs taken in New Caledonia show an undersurface colour similar to AM Sky. It is not a 'cold' neutral grey like AM Sky Grey or "aircraft grey". Although colour images are inherently unreliable, these provide a counterpoint to the 'Sky Grey theory' which, it seems, is based entirely on the appearance of colour photographs. The New Caledonia photographs also provide a corroborative/cumulative strength to the other evidence.

7. Airacobra aircraft repainted in Britain reveal the original stencils masked off on the factory applied high demarcation undersurfaces and retained on lighter rectangles of paint. If the undersurfaces were Sky Grey (or similar) the RAF would not have re-painted them in Medium Sea Grey. The aircraft were re-painted specifically to comply with the Day Fighter scheme for squadron trials and operations over Europe. It is clear from the extant documentation about this that the original factory finish was Dark Green, Dark Earth and Sky.

8. The AM, MAP and RAF did not require aircraft with the undersurfaces painted Sky Grey or "aircraft gray". They wanted Sky (aka Duck Egg Blue) and said so. Du Pont matched that requirement and their colour, 71-021, served as the match sample for other US paint manufacturers.

Now, what exactly is the evidence for the "point of view" that these aircraft had Sky Grey or "aircraft gray" undersurfaces? A colour photograph of AH621 where the undersurface paint looks slightly too greyish or too blue for Sky? Of course one might believe Bell did not follow their own specification or MAP's, and instead obtained inferior paint from a contractor which had the appearance of AM Sky Grey or "aircraft gray", but to do so in dismissal of the documented evidence really requires something more robust than just an opinion. That flawed logic also leads to an open conclusion that any colour might have been used - so why restrict the field to AM Sky Grey or "aircraft gray'? It also conveniently ignores the rather testing acceptance procedures and documentation implemented by MAP and the AM, which are available for researchers to examine.

Were there variations in the appearance of the colour? Of course.

Dismissing documentary evidence obtained through serious research as "points of view" demeans the very nature of research.

RAF Fortress Camouflage

2009-04-05T05:37:00.000-07:00

These Boeing factory drawings show the colour scheme and markings specified for the Fortress II destined for the RAF.

The paints as specified are Fuller Enamels (also used on the Boeing-built Bostons) and the undersurface paint is described as 'Deep Sky Blue'. The wing walkway lines are specified to be Dull Red.

More on Deep Sky Blue in due course but it is clear from original RAF documents that it was considered to be a different colour from PRU Blue to which it has often been matched. Further the MAP Du Pont colour card has chips for 'Deep Sky Blue' 71-065, & 'Deep Sky' 71-052 which are quite different from the P.R.U. Blue chip 71-068 also included.

No doubt the usual forum gremlin will pop up and bleat that specifications were not always followed, so that any colour opined by him is a better choice. In the absence of any other evidence (as opposed to opinion or "points of view") this author prefers primary source material such as this factory drawing and the contemporary colour cards upon which to base conclusions.

Colour photographs are never to be trusted, especially formatted digital images but note from interest the light and sandy appearance of the 'Dark Earth' in contrast to the other colours.

There is a useful 14-page article on RAF Fortress camouflage and markings by Paul Lucas in the British magazine 'Model Aircraft Monthly' for August, 2007 (Volume 6 Issue 8). This includes a colour four-view by Peter Scott based on the Boeing drawing and the caption goes into some detail about the markings.

Du Pont 71-021 Sky-Type S Grey

2009-02-04T14:09:00.001-08:00

Du Pont 71-021 was the paint standard cited by the BPC as the sample for the Duck Egg Blue required on the undersurfaces of aircraft destined for the RAF. Although the Du Pont name for this paint included the word "grey" the paint was actually a very pale blue green, like a lighter, brighter version of RAF Sky.

The Du Pont 71 series colour card chip is much closer to RAF Sky than this full size swatch of actual paint. The colour card chip is warmer, slightly more greenish and less blue. It is exactly similar to the appearance of the undersurfaces of AVG Tomahawks in at least two, well known colour photographs.

It does not imitate Sky Grey in any respect. Whilst there is no doubt that some of the paints applied to US aircraft for Britain may have appeared more like light grey than Sky this is not the same thing as the paint being matched to Sky Grey to begin with.

The colour space occupied by 71-021 and Sky is subtle and easily shifted in photographic or digital images to appear more grey. The pigment characteristics of these colours will be explored in more detail in a subsequent post.

Duck Egg Blue, Sky Grey and the Flying Tigers ~ Part One

2009-01-31T07:07:00.000-08:00

In recent years a trend has emerged promoting the idea that the undersurfaces of early US export aircraft for Britain were painted in light greys chosen from existing US standards and matched in error to the AM colour 'Sky Grey' rather than the 'Sky' colour required by the RAF. This idea began with Terrill Clements' analysis of the colour schemes of the American Volunteer Group (AVG - the 'Flying Tigers') Tomahawk aircraft, originally destined for the RAF but transferred to the Chinese:

"The lower surface camouflage of the AVG's Tomahawks is even more interesting. While British contracting officers would likely have specified the complex greenish colour known as Sky at the time these aircraft were ordered, the best colour photographs and film of AVG Tomahawks indicate that their lower surfaces were in fact painted light grey. It appears that other American manufacturers had themselves employed a range of light blues, greys and greens when first coming to grips with the new requirement for Sky undersurfaces in mid-1940".

"As yet no clear explanation for this anomaly has been found. Perhaps American manufacturers simply misunderstood British requirements that often rendered the name as 'Sky Type S Grey'. Indeed the observed light grey is remarkably similar to British Sky Grey. Or perhaps the requirements of other customers, or evolving British specifications for tropical schemes, were a factor. In any event, another existing American military colour, Aircraft Grey (later designated ANA 512), is an excellent match for the British Sky Grey and the observed colour on the bottom of the AVG's Tomahawks."

Mr Clements' hypothesis, which has been widely taken up and even promoted as definitive by one particular modelling forum, is possible but in the light of all other evidence not probable. It relies almost wholly on evidence type 3 as summarised in the Introduction here and all the other associated possibilities are conjecture. So far no documentary evidence has been published to support the theory that 'Sky Grey' was mistaken for 'Sky' - or that an available US military paint standard similar to AM Sky Grey was used instead.

The most significant flaw in this hypothesis, leaving aside for the moment the question of the reliability of wartime colour photographs in determining accuracy of colours, is the fact that the contemporaneous factory painting diagrams for many US types intended for the British do not use the term 'Sky' but rather 'Duck Egg Blue' instead. It is much harder to argue a possible confusion about Duck Egg Blue where the colour Sky Grey might have been misidentified as an alternative.

Hard primary evidence suggests in fact that the earliest US attempts to match 'Sky' may have resulted in a very bright pale blue colour - possibly matched to AM Sky Blue - which was nothing like Sky Grey. Early Martlets were painted in this pale blue, which has been found on the undersurfaces of the extant Fleet Air Arm Museum example AL246 and identified as the factory applied paint, well preserved by the paint layers applied over it for 60 years (see pic above). The pale blue colour is also mentioned in a contemporaneous report and was the subject of comment in other official correspondence drawing attention to its marked difference to the more familiar indigenous Sky paints. Further, extant Grumman paint shop diagrams for G-36A contract F-292, G-36B contract A-1548 and F4F-4B contract 83734 all show the undersurfaces as to be painted 'Duck Egg Blue'.

Later it appears that the issue was resolved by the availability of paint much closer to the required Sky in appearance. Noted US researcher Dana Bell has thrown some light on the way that colour requirements were communicated to the US manufacturers at the time:

"The first document I found was a 12 March 1942 memo from the British Air Commission to the (US) Defence Aid Organisation requesting that all future B-17Es be delivered in Extra Dark Sea Gray and Dark Slate Gray over White (the temperate ASW scheme). What makes the document important is its explanation of the BAC's mechanism for communicating color standards at that time. All color names are followed by a Dupont color number. The letter states, 'I have quoted the Dupont colour numbers since these are in a booklet which the Defence Aid Organisation has and further it may accelerate the ordering of paints. The British Air Commission has no special preference for Dupont, but it gives easy reference.' This is the first indication I've seen showing how the BAC told Americans to match the Air Ministry colors."

Mr Bell's assessment is supported by the provision of Dupont paint documents and swatches, including a colour card for RAF aircraft types, in British file archives relating to the British Purchasing Commission (BPC), the Air Ministry (AM) and the Directorate of Technical Development (DTD). Whilst it is quite true that not all US aircraft manufactured for export to Britain were painted using Dupont paints there is strong evidence that the paints used were matched to those Dupont colours which had been identified as suitable equivalents for the RAF/FAA colours required by the British.

To be continued . . .

Introduction

2009-01-28T04:32:00.001-08:00

One of the main reasons I started this particular blog is in order to be able to consolidate information into a single resource. Another reason is because of the transient and often misleading information about this subject on modelling forums. Information which is sometimes based on hypothesis or even opinion is often presented as definitive. There is a lack of rigour in some of the research, where evidence is "cherry picked" to support a particular hypothesis. Modellers who want to paint their models a certain way are very stubborn when it comes to resisting pieces of evidence. There is nothing wrong with that. It is a modellers right to paint the model according to his or her interpretation - the problem arises when that interpretation is presented as definitive or the result of research which actually isn't. Trawling various opinions from modelling forums across the internet is not research and unfortunately many of the "research articles" at these sites are just vehicles for pre-conceived and subjective opinions on the subject, often resorting to that fallible dark art of interpreting monochrome photographs (or assuming that colour photographs provide an accurate impression of colours).

The best evidence is cumulative. In respect of paint colours it usually consists of, but not limited to:-

1. Paint standards, including orders, specifications, paint charts and swatches; correspondence, memoranda and official instructions; dated factory painting diagrams where paint specifications are cited are especially useful; pigment formulae, where known, can be especially useful in recreating the intended appearance of the original paints.

2. Extant samples, either applied paint or swatches, measured using spectrophotometric equipment and matched to other standards using modern colour management equipment and software;

3. Colour photographs; but beware of these, especially scanned and formatted digital images on the internet; run a hundred miles when someone tells you they have "corrected" the colours using Photoshop. Original prints are best.

4. Contemporaneous paintings, notes and sketches, including objective eyewitness reports (e.g. where the observation is directly related to colour rather than incidental to it); the reports of some early observers, such as Ian D Huntley and M J F Bowyer, are often disregarded or forgotten but in fact remain valid and useful.

5. Monochrome photographs; not reliable when it comes to determining colour but useful where details may be observed putting other aspects into context.

Be suspicious of anyone basing a hypothesis on only one of these elements, or worse, deliberately ignoring the others. The application of the principle of Occam's Razor* is recommended - that the explanation of any phenomenon should make as few assumptions as possible, eliminating those that make no difference to the observable predictions of the explanatory hypothesis or theory. This is often paraphrased as "All other things being equal, the simplest solution is the best".

* The principle attributed to 14th Century English logician and Franciscan friar William of Ockham.

Welcome to AmAir4RAF

2009-01-14T04:53:00.000-08:00

Welcome to American Aircraft for the RAF (AmAir4RAF), a new blog devoted to information and discussion about the US manufactured aircraft supplied through direct contracts and lend-lease to Britain during the Second World War. The blog will focus on colours and markings, but also provide a one-stop resource for detailed information about serial numbers, deployment dates, units and fates, exploding many myths and assumptions. In the course of time the coverage will extend to ex-RAF contract aircraft supplied to the Soviet Union, China and other countries.

Please comment and contribute in order to enrich this blog as a free resource for researchers, historians and modellers.