F.6/42 aircraft made obsolete by the Griffon-powered Spitfire?

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Staff Sergeant
Nov 3, 2022
Mansfield, Ohio, USA
F.6/42 was an Air Ministry/RAF RFP for interceptor fighters powered by 2000-2500hp class engines (Rolls-Royce Griffon, Napier Sabre and Bristol Centaurus). These aircraft were expected to be fast, fast climbing, very maneuverable (especially given their engine power and size), and armed with 4x20mm cannons. The ultimate winners were the Centaurus and Sabre powered versions of the Hawker Fury (though not actually part of the original tender, though was submitted as a private venture to the RAF as a successor to the Hawker Typhoon/Tempest), and the Folland Fo.117. The Fo.117 was never actually built and the Centaurus Fury was never ordered by the RAF in quantity (though it would form the basis of the RN's Sea Fury), and the Sabre Fury was ultimately cancelled in favor of jet fighters.

However, I'd argue that the Griffon Spitfires, namely the Mk 14 and Mks 21, 22 and 24 made the F.6/42 aircraft obsolete to requirements even before any of them flew, mostly by meeting most of the requirements out of the gate (though not designed for them explicitly), and getting into production sooner.

As mentioned, the Fo.117 was never built or flown, and the Hawker Fury didn't fly until the Sept. 1944. By then, the Spitfire 14 has been in service for several months. It would seem that the Spitfire 14 met or came close to meeting the F.6/42 requirements in most areas. The only areas that the 14 lacked in was maybe top speed (though marginally) and the fact that it didn't carry 4 20mm cannons are standard armament (the C and E wings were capable of it, but usually carried either 2x20mm/4x.303s or 2x20mm/2x.50s).

Of course, the Spitfire 21/22/24 it could be argued met that spec even more closely, though again weren't developed for it (basically intending to bridge the gap between the Spitfire 14 and the anticipated Spiteful with its strengthened wing and improved ailerons). Of course, jets like the Meteor and Vampire basically killed the Spiteful, but the 20 series Spitfires also (IMO at least) didn't help. Though slower in a straight-line than the Spiteful, the 20 series Spitfires had the same climbing ability, same 20mm cannon armament (as specified in F.6/42, and with more RPG than the Spiteful and easier reloading/servicing), and handled better, especially on take off and landing (still had the disadvantage of the narrow main landing gear, but stall and low speed qualities were significantly better than the Spiteful).

I'd argue, in addition to emerging jet fighters like the Gloster Meteor and especially the DH Vampire (a single seat, single engine jet answer to the F.6/42 concept), the Spitfire 14 and 20 series were sufficient to meet the F.6/42 requirement in all but name, and were in production much earlier than the never built Fo.117 and the ultimately prototype only RAF Fury, though that program did give the RN the Sea Fury.

Any thoughts on this having happened, even if it was only a coincidence?
The reason why I asked this was with the Griffon powered Spitfires was the F.6/42 fighters really needed (none entered production aside from the Hawker Sea Fury for the RN due to early jets not being well suited for carrier work)? Or was it not expected that the Griffon Spitfires would easily attain such performance?
Performance wise, probably, but given the aircraft it produced I would imagine the specification also stipulated the ability to carry a decent ordinance load, and enough range to serve as an escort fighter, both respects in which the XIV fell notably short. The Mk 21 and especially the eventual 24 improved upon those shortcomings somewhat, though range in particular was still well behind the Sea Fury — a notable improvement on the Tempest, which wasn't much better than the Griffon in terms of range. The Fury/Tempest also outperformed the Griffon Spits pretty handily at low altitude, which given the context of a 1942 specification to counter the Fw 190, may have been deemed relevant — perhaps less so by the time these aircraft were actually becoming available, but then again, given the Tempest's operational profile, perhaps not.

All that said, one also has to consider that these specifications were often more or less written with a winner already in mind, and that those decisions were probably made with (at least) half an eye to strategic/industrial concerns. Does a Tempest light fighter make more sense from a development perspective than a Griffon escort fighter? Who knows. The more important question may be whether Supermarine has the excess capacity to develop and produce such an aircraft, and just as importantly, what is Hawker supposed to do with their production lines in the mean time? What about Napier?
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Actually, looking at the aircraft submitted, none of them had sufficient range to serve as a bomber escort (namely the Folland Fo.117 that won the tender among aircraft directly submitted--the Hawker Fury also was declared a winner, but was separate from the spec). Most of the fighter designs submitted had ranges that I would consider insufficient for escort duty compared to the P-51 Mustang for example. The Fo.117 had a range of just over 500 miles on internal fuel . And the Sea Fury had a range of 780 miles (I can't find anything for the Sabre Fury, while BAE's Heritage site lists 700 miles range), which was about the same as a Tempest V.

Spitfire 14 was capable of speeds of up to 390 mph at sea level (but with 25 lbs supercharger boost and 150 octane fuel), and though I'd obviously say that a "lightweight Tempest" would be appealing, considering that aside from a reduced wingspan, the Fury/Sea Fury was almost as big and heavy at a normal Tempest--IMO, not much of a "light fighter" compared to the Spitfire 14 (normal max take off weight of 8500 lbs, and even the 20 series Spitfires were quite a bit lighter than the Fury/Sea Fury).

Of course, I've tried to find a detailed listing of the F.6/42 RFP specs, and haven't found much aside from the fact that the RAF basically wanted an "improved" Fw 190 in terms of performance.
At least part of the Sea Fury's extra weight will be from it's being a naval fighter, but I agree, it didn't end up as much of a "light" fighter, even in comparison to the Tempest. Still much better practical range than a Mk XIV though (not as good as a Mustang, but enough to give you some more tactical felxibility), better ordinance options, and better performance down low. A Griffon with 25 lbs boost was now slouch at any altitude, but a Tempest II was pushing 415 on the deck with 150 Octane. Numbers cited for the Sea Fury are usually lower because they were achieved under post-war operating limitations intended to improve engine life, but with its smaller wing and lower rated altitude the Sea Fury would have been even faster under similar engine settings. It's a much better tactical fighter in other words. What the Griffon Spit gives you is an absolutely monstrous rate of climb, and superb high altitude performance — despite all the evolution it had undergone, the Spit remained a pure interceptor at heart. How useful that was by mid 1944 (nevermind 45) is another matter. If the question is which I'd rather find myself flying in a randomised dog fight scenario, the answer is the Spit, but if I'm an RAF big wig making purchasing decisions, the Fury probably makes more sense (though cost still plays to the Spit's favour).

The various RFPs involved in the Tempest/Fury development are kind of mind boggling tbh. F.6/42 was, as I understand it, not actually even for a "Tempest Light Fighter" but as you say, an Fw 190 killer, however it was issued at around the same time as the annoyingly similarly named E.6/42 which was for a purely experimental (hence E) lightweight version of the still-in-development Tempest (F.10/41 "Thin-Wing Typhoon"). Hawker apparently decided to kill three birds with one stone, submitting variations of the same design for both of those, as well as N.7/43 for a carrier based fighter, and so E.6/42 was rewritten as F.2/43 for a Tempest Light Fighter (same basic concept but now an F instead of an E), and N.7/43 was revised as N.22/43, apparently also to suit the navalised Tempest/Fury proposal. I believe at least a few of the Fury prototypes were even modifications of the Tempest prototypes, so intertwined were their developments.

Again, though, I don't think it's possible to overstate industrial concerns in these decisions. Hawker was a major defence contractor, their financial health was a strategic interest of the state, and even ignoring that, their production lines couldn't just sit idle. Retooling to produce long-range Spits under license would have been a waste of time and resources (never mind the political headache), as well as a major cost for the company. It was in everyone's interest that they pursue development of the Tempest/Fury line, even if a Supermarine alternative might have been just as practical (and who knows if it would have been).

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