Contracts and Colours

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

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

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

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.

Image credits: Courtesy of & © 2009 David Muir

P-40E Mysteries ~ Part One

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

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

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.