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When working on my new book 'Mustang: The Untold Story', it became clear that there is an awful lot of confusion about the early marks of North American Mustang/P-51. So here's a thread to try and sort it all out @BoneyAbroad (1
There were 4 production variants of the Mustang before the Merlin was introduced - a lot of people think it's only the P-51A! A lot of the confusion starts with the prototypes. The 1st Mustang prototype was the XP-51, right? Wrong. The original Mustang was known as the NA-73X (2
Here's the NA-73X. The number comes from the fact that it is North American's (NA) Model no. 73, and is experimental (X). First pic is the NA-73X on rollout, second is after a post-crash rebuild and return to flight. This aircraft often confused with XP-51 - it is different (3
The first *production* variant of the Mustang was for the RAF. It retained the North American model number of the prototype (NA-73), and was known as the Mustang Mk I. It has no equivalent in US service. HOWEVER... (4
Part of the deal for the British being allowed to buy the Mustang was that 2 from the first 10 production machines be passed to the USAAC for testing. Because they were now in US service, the type was given a US designation - P-51- and as experimental, XP-51. Here they are (5
..The two XP-51s were production RAF Mustang Mk Is with US equipment and small mods. Meanwhile, the British had ordered more Mustangs, in a new variant with cannon armament. This was designated Mustang Mk IA (US markings on 2nd pic because it is pre-delivery) (6
The Mustang IA was the first ordered under lend-lease instead of directly purchased. Because they technically began life as USAAF aircraft, they had a US designation - P-51, and as per the convention at the time, as the first production model, they had no suffix. Plain P-51 (7
When Pearl Harbor brought the US into the war, the USAAF held on to 54 of the RAF order for Mustang IA. These now became P-51s in formal USAAF service. Like the RAF, these were used in the tactical reconnaissance role rather than fighters, leading to MORE CONFUSION (8
At this point, USAAF lacked a specific designation for reconnaissance aircraft, but later did so and termed recon Mustangs F-6s. And because they'd now decided it was too confusing for the first variant of any type not to have a suffix, these first tac-R Mustangs became F-6A (9
HOWEVER it seems unlikely that these Mustangs were ever called F-6A when they were in service. So let's forget that for now and go back to calling them P-51, as everyone did at the time. By this time, USAAF wants to order Mustangs directly (10
But USAAF has enough fighters for now, and is pursuing P-47 as main future fighter. Still, the P-51 is excellent at low altitude and what the US *really* needs now is high performance attack aircraft. NAA quickly prepares a dive-bomber variant. USAAF agrees, calls it A-36 (11
To sum up here, that's three service versions of the Allison Mustang and we haven't got to the P-51A yet. Because the USAAF now applies a suffix to all versions, even the first, the A-36 is technically the A-36A. It's a proper dive bomber, but also good as a fighter (12
Only now, in mid-1942, is the USAAF able to order its own fighter version of the Mustang, setting out its own specs from the start. This is - finally - the P-51A. An Americanised, improved version. These mainly saw service in the China-Burma-India theatre (13
Because the USAAF had nabbed 54 of its Mustang IAs, the RAF received a similar number of P-51As, which it designated Mustang Mk II seen here testing loooooong range ferry tanks) (14
And the USAAF also recognised the type's tactical reconnaissance strengths and modified a handful to that spec, which saw considerable service around the time of D-Day. Confusingly, as mods of the P-51A, they were designated F-6B. (15
This is a bit of a whistle-stop tour, but I hope will help to tease out the variants, their differences, and the order they came in. Lots more detail in the book Mustang: The Untold Story from @FlyPastMag on sale now! https://shop.keypublishing.com/product/View/productCode/KB0036 (16/16 ENDS
