Speculative thread: Early Mustang envisioned for Merlin power, GP fighter/interceptor

[BarnOwlLover2]

Now this is a big "what if". What if the Mustang was envisioned as a Merlin powered general purpose fighter and interceptor from the beginning? This would take some changes to the real world timeline (like North American being aware of the two-stage Merlin earlier, etc), but I do wonder what thoughts and speculations would be.

Now the parameters:

-Built to British or optimum mix of British and American loading standards
-Intended to be engineered to take a two stage Merlin from the start
-Answer to British (and later USAAF) criticism of the hinged and framed canopy (my solution would be a Typhoon type bubble canopy or a two-piece canopy similar to the Yakovlev fighters or the Lavochkin La-5/7, maybe even La-9 or -11)
-Carry suitable armament for a 1942-era interceptor
-Be open for future development

So in this alternate time line, what would it look like, how would it perform, and how favorable would it be to go on to fufil the role for bomber escort later on?

 

[Archibald]

France Fights On does exactly that. With Vichy nipped in the bud (mostly, Pétain blows an aneurysm in anger) and the bulk of France - economy and military and politics and everything else but the kitchen sink - moved to Algiers, June - August 1940... the AdA needs a successor to the D-520 that can't be manufactured in North Africa; and one that is less expensive and a better plane that goddamn Curtiss P-40.
Since 1939 France was already a massive NAA client via the NA-16 orders (T-6 direct ancestor) the NA-40X in October 1940 is quite welcome... unlike OTL. The USAAC might be happy with P-40s and the British with Spitfires and Hurricanes, France is not... moar Curtiss are bought (Hawk 81 - 87) but at some point, Curtiss decline and dismal prices are too much for Cash & carry, before Lend Lease kicks in.

 

[Nicknick]

The Merlin wasn't really the better engine in generall, but it had a better mecanical superchager than the Allison (which were focusing on the Turbosupercharger). Instead of swapping to the Merlin, they might as well have used the Merling charging system (of course with the required adaptaions) on the Allisons.

 

[riggerrob]

A dedicated interceptor would likely be stripped of any extraneous weight to improve climb performance. That would entail deleting the L-shaped aft fuselage tank, improving balance, but curtailing range.
A long-range escort fighter would require a major re-design to increase fuel capacity … perhaps an entirely new wing like the P-47N.

 

[BarnOwlLover2]

This could (and maybe should) be spun off as a separate topic, but what about the XP-51F/G Mustangs in the interceptor role? Namely, how good might they have been, and what would their armament be in Interceptor trim (type of guns and ammo capacity)?

 

[Desertfox]

Isn't that basically a P-51B with Malcolm Hood and the Mk IA armament, just earlier?

Shame the Allison XP-51J never got a chance to shine. It was by far the best looking version.

 

[BarnOwlLover2]

The XP-51F/G/J were lightweight Mustang developments that lead to changes that were incorporated into the P-51H and the F-82 Twin Mustang. They differed largely in engines fitted (Packard V-1650-3/7 in the F, Rolls-Royce Merlin RM 14SM/Merlin 100 in the G, Allison V-1710-119 in the J).