- Phase 2.7 is release of Y version meeting agreement (not always followed - NA-73 and P-47 are specific examples where production was authorized before testing improvements.
- Phase 2.8 is release of early production series to customer (ie BPC/RAF) to perform Operational Suitability Testing, which if accepted as is, leads to deployment to Training and operational units for training prior to combat
This is a confused muddle of specific US and RAF processes all of which fall under 'phase two'
(P-40K/N assigned to Air Training Command, P-39 also assigned to train units in States, P-63 deployed to ATC and Russia)
P-40K was one of the most successful P-40 variants and in wide / heavy combat use with the RAF, RAAF, Soviets, US 57th FG in the MTO, and 23rd, 51st, and 80th FG in the CBI. There were more aces flying the P-40K than P-38E or F for example.
P-63 was designed for the Russians with direct Russian involvement. It was changed after early combat experiences per their request.
Phase four as you presented is actually Phase 2.8 above
Actually no, you completely missed the point - very often aircraft made it through all the testing and acceptance phases, got into combat and were found to be extremely unsuitable for the intended mission when faced with actual enemy aircraft. Example I cited above such as the Defiant, the F2A and Me 110 were either quickly phased out or given a new mission (Me 110 converted to night fighter) or like the Ki-43, they were 'sent back to the drawing board' with fairly significant changes made.
During WWII in US, your Phase five was eliminated before order placed for high quantity production - examples given include P-47B, P-51B which were contracted for production before first actual prototype flight.
Yes and quite often production orders were immediately cancelled or drastically reduced as soon as the aircraft got into combat. For example the USAAF ordered 80 P-43s, but as soon as early models did poorly in Europe they cancelled the order and Seversky went back to the drawing board, ultimately leading to the P-47.
Perhaps a more salient example, the Luftwaffe put in an order for 1,000 Me 210 before they were even flown. But all the numerous problems led to a drastic reduction in that order and only 90 were made. Ultimately they kept modifying them until they came up with the Me 410 (a bit too late)
In many examples, the Specifiers were way off and the designers did a credible job of design/fab to spec. Where many designers
Ultimately it was kind of irrelevant if the problems were with the specs or the actual design or both (usually it was both). Corporate and military bureaucracy rarely predicted or implemented the design for the the actual needs well, let alone perfectly.
P-40 4-26-38 to 9-1940 (Russia)
P-47 9-6-1940 to 4-8-1943 (8th AF)
P-51 4-12-1940 to 5-10-1942 (RAF)
P-51B 8-25-1942 to 12-1-1943 (9th AF)
P-40 flew in combat in 1940? That's news to me. I think it would be a neat trick considering the first ones arrived in Russia in August and September 1941 (from English and US sources respectively) according to
this article
Allison P-51 continued to be 'modded' long after may 1942
P-47 had a particularly long teething as mentioned re: the P-43 above.
S