British escort fighter--what might it have been like?

[NevadaK]

NAA had quite a few projects going before 1940.
NA-16 (trainer BT series)
NA-19 (trainer BT series)
GA-15 (observation O-47)
NA-26 (trainer SNJ/AT-6)
NA-50/68 (fighter P-64)
NA-64 (trainer "yale")
NA-69 (attack A-27)

And of course, the B-25 was under development, soon to be introduced.

The aircraft listed do not include a few prototypes developed but never produced (XB-21, NA-35, etc.)

Thanks GrauGeist,

Yes and no.

NA-16 (trainer BT series) minimal production
NA-19 (trainer BT series) direct development from NA-16, around 250 made, out of production in 1940
GA-15 (observation O-47) minimal production, out of production 1940
NA-26 (trainer SNJ/AT-6) Major contract
NA-50/68 (fighter P-64) 13 built. Developed from the BT-16
NA-64 (trainer "yale") BT series aircraft, out of production.
NA-69 (attack A-27) T-6 Texan

So in reality, more like three: the BT, the O-47, and the T-6. The B-25 and P-51 were huge leaps for NAA. The point I was trying to make earlier is that one shouldn't count out small manufacturers as sources of innovation. In 1940, NAA fit the mold as a small low performance aircraft company.

 

[GrauGeist]

But for a small company like North American, those aircraft they were producing (some types well into the hundreds) was a significant amount, especially when small aircraft firms were struggling due to the depression.

Their clean sheet proposal to the BPC was a huge leap of faith.

 

[BarnOwlLover]

I wonder if a fighter that used the Merlin RM.17SM would need Griffon-like cooling needs, given that it made up to 2640hp on 36 PSI boost and needed ADI for that as well as 150 octane fuel (normal power would've been about 2200 hp and normal sprint/WEP would've been 2380hp).

 

[Shortround6]

You may very well be right.

The Problem with these high boost engines (Sprint?) is that often the cruise and climb (30 minute) ratings don't follow.
Even the 100 Series engines were rated at 2850rpm and 12lbs of boost for climb.
Even if rated at 25lbs boost for combat they were rated at 18lbs of boost for take-off.

This basically means that Griffon powered aircraft can have more power available for take-off and climb on a regular basis (like climbing to 30,000ft) even though there may altitudes or short periods of climb where the super Merlin may be superior.

 

[Geoffrey Sinclair]

North American 1938 to 1940 Ignoring the prototypes and the small runs including foreign sales.
O-47A 77 in 1938, 87 in 1939, O-47B 31 in 1939 and 43 in 1940
Harvard/NA-16 37 in 1938, 393 in 1939
BC-1/BC-2 177 in 1938, 3 in 1939
Harvard/BC-1A/AT-6/SNJ/NA-27/NA-71 598 in 1940, plus 16 SNJ-1 in 1939 and 36 SNJ-2 in 1940 on Navy contracts.
BT-9C 35 in 1938, plus 12 NJ-1/BT-9B
BT-14/NA-64/Yale 230 in 1939, 531 in 1940.

Totals 338 built in 1938, 760 in 1939 and 1,208 in 1940.

There was the NA-40 in early 1939 and its reported performance. The B-25 contract for 184 examples was dated 20 September 1939, as of March 1940 an initial example was expected in June or July 1940 and production to fully commence in September 1940, but acceptances did not start until February 1941. The NA-73 schedules were similarly optimistic with 420 were supposed to be delivered by end November 1941, the reality was 69 acceptances.

Most of North American's order book was still foreign in early 1940. The USAAF BC-1A contract active in March 1940 was dated 21 October 1938 for 83 aircraft, the AT-6A same date for 94 aircraft. While Curtiss had USAAF orders for 524 P-40 and 203 O-52 plus the foreign orders.

 

[wuzak]

I wonder if a fighter that used the Merlin RM.17SM would need Griffon-like cooling needs, given that it made up to 2640hp on 36 PSI boost and needed ADI for that as well as 150 octane fuel (normal power would've been about 2200 hp and normal sprint/WEP would've been 2380hp).

It was rated 2,200hp MS and 2,100hp FS gear. It was flight rated to 2,380hp, but that's only for testing.

2,640hp was with +36psi boost, PN 150 fuel + extra TEL and ADI and higher rpm.

Cooling systems, if I understand it correctly, were designed around normal power levels, not combat/WEP.

 

[D. Mylchreest]

Martin-Baker MB-3?

 

[BarnOwlLover]

Now a theory for essentially a British equivalent to the Mustang in concept, which IMO is only possible (or at least most likely) after the two-stage Merlin became available in quantity during 1942. Would an aircraft about half the size of a DH Hornet (as a single engine fighter) or a true lightweight Tempest development (like a lightweight/scaled down Hawker Fury powered by a Merlin or maybe a Griffon) fit the bill here?

I'm asking because, one, there one side where aircraft like the La-9/11 and the Ki-84 and Ki-100 showed that you could get long range out of a relatively lightweight fighter, while still having formidable performance, armament and protection. And on the other end, Rolls-Royce used a P-51B Mustang as an engine test bed for the Merlin 100 program, first with a Merlin 65 modded to emulate the 100, then an actual 100 series engine. Top speed went up from 440 mph to 455 mph, but more importantly, climb went up from 3650 fpm to 4500 fpm, which was better than many dedicated interceptors at the time.

So why not take a relatively small aircraft that still had respectable range, good firepower, very good maneuverability and speed, and maybe use it a multi-role fighter capable chiefly of both interception and escort duties? Of course, this would essentially mean designing a new aircraft, since just adapting an existing design wouldn't completely fulfill this requirement/desire.

Granted, in reality, the Mustang and the Merlin was a fortuitous combination that would make a formidable escort fighter (though I'd argue, that like with most things, and as hinted above, it could've been improved, even without the lightweight Mustang program that yielded the P-51H). Also, the Hawker Tempest II was intended to be used as a bomber escort in the Pacific had the war there gone on much longer, as well as the Hornet and maybe the Fury/Sea Fury.

 

[tomo pauk]

I'm asking because, one, there one side where aircraft like the La-9/11 and the Ki-84 and Ki-100 showed that you could get long range out of a relatively lightweight fighter, while still having formidable performance, armament and protection.

So why not take a relatively small aircraft that still had respectable range, good firepower, very good maneuverability and speed, and maybe use it a multi-role fighter capable chiefly of both interception and escort duties? Of course, this would essentially mean designing a new aircraft, since just adapting an existing design wouldn't completely fulfill this requirement/desire.

The La-9/-11 with a good V12 in the nose and a pair of drop tanks would've been really good.
We'd need a new place to install the 'normal' British armament (at least 2 cannons + 4 LMGs, or +2 HMGs), the wing tanks might not like that idea.

Ki-61/-100 and Ki-84 were the size of Spitfire. These aircraft were far more conductive for a long-range role than the small aircraft.

 

[pbehn]

The La-9/-11 with a good V12 in the nose and a pair of drop tanks would've been really good.
We'd need a new place to install the 'normal' British armament (at least 2 cannons + 4 LMGs, or +2 HMGs), the wing tanks might not like that idea.

Ki-61/-100 and Ki-84 were the size of Spitfire. These aircraft were far more conductive for a long-range role than the small aircraft.

Until you have a two stage Melin what is the point of longer range? They should have tooled up to produce Mustangs, it was discussed but never done, in any case the British got a good number of P-51Bs Ds and Ks.

 

[BarnOwlLover]

The La-9/-11 with a good V12 in the nose and a pair of drop tanks would've been really good.
We'd need a new place to install the 'normal' British armament (at least 2 cannons + 4 LMGs, or +2 HMGs), the wing tanks might not like that idea.

Ki-61/-100 and Ki-84 were the size of Spitfire. These aircraft were far more conductive for a long-range role than the small aircraft.

The plane that I'm looking at is, as mentioned before, "half a DH Hornet" as far as weight. The Hornet was initially designed with a normal take off weight of about 15,000 lbs being envisioned. Granted, they could lift off with quite a bit more weight than that, but the Hornet F1 did have a clean but armed/equipped normal take off weight (according to the book DH Hornet and Sea Hornet: de Havilland's Ultimate Piston Engine Fighter) of about 14,800 lbs if I remember correctly. That means that half a Hornet, even if we're talking the F3 or the Sea Hornet F20, would weigh (all things being equal) approx 7500-8000 lbs. Which is about what a Spitfire IX and VIII weigh approx. Though you'd (as I envision it at least) get 4x20mm cannon armament as standard and a lot more range than those Spitfires were normally capable of, especially on internal fuel (important for both escort work and say standing patrol interceptions of V1 flying bombs).

And as mentioned, maybe something like the Fury/Sea Fury could work if available earlier, but is a fair bit bigger and heavier than what I'm looking for.

 

[wuzak]

The Spiteful could have been an escort fighter IF the MAP had said to Supermarine that they wanted a longer range.

As it was, the Spiteful's wings were very thin, so not going to get a lot of fuel in them. But, if the requirements demanded it, they could have been made thicker to allow for wing tanks.

 

[Acheron]

Everyone talking about the technological possibilities of a British escort fighter. Since this is Britain, shouldn't we rather be discussing about which dynastic marriages would be required for the RAF to even entertain the possibility of such a thing?

 

[tomo pauk]

The Spiteful could have been an escort fighter IF the MAP had said to Supermarine that they wanted a longer range.

As it was, the Spiteful's wings were very thin, so not going to get a lot of fuel in them. But, if the requirements demanded it, they could have been made thicker to allow for wing tanks.

See the Spiteful with many fuel tans here.
Strong side of Spitifre/Spiteful was the fuselage of generous size, with many options for a lot of fuel already there, before we even consider the wing tanks.

 

[wuzak]

See the Spiteful with many fuel tans here.
Strong side of Spitifre/Spiteful was the fuselage of generous size, with many options for a lot of fuel already there, before we even consider the wing tanks.

Sorry, can't see that.

 

[tomo pauk]

Sorry, can't see that.

Probably you need to be logged up to the secretprojetcs.
Here is what is posted on oldmachinepress:

The all-metal, monocoque fuselage of the Spiteful was similar to that of the Spitfire. The cockpit was raised to improve the pilot's view over the aircraft's nose. A new, sliding bubble canopy covered the cockpit. Four fuel tanks in the fuselage, forward of the cockpit, held a total of 120 gal (100 Imp gal / 455 L), and a tank in each wing root held 10 gal (8 Imp gal / 36 L). Starting with the third prototype, a 74 gal (62 Imp gal / 282 L) fuel tank was added behind the cockpit, bringing the total internal capacity to 214 gal (178 Imp gal / 809 L).

 

[NevadaK]

Probably you need to be logged up to the secretprojetcs.
Here is what is posted on oldmachinepress:

The all-metal, monocoque fuselage of the Spiteful was similar to that of the Spitfire. The cockpit was raised to improve the pilot's view over the aircraft's nose. A new, sliding bubble canopy covered the cockpit. Four fuel tanks in the fuselage, forward of the cockpit, held a total of 120 gal (100 Imp gal / 455 L), and a tank in each wing root held 10 gal (8 Imp gal / 36 L). Starting with the third prototype, a 74 gal (62 Imp gal / 282 L) fuel tank was added behind the cockpit, bringing the total internal capacity to 214 gal (178 Imp gal / 809 L).

It's interesting how the design timeline for the Spiteful matches the OP's proposal, yet increased range isn't a goal of the effort. To me, if a purely UK developed long range escort fighter would bear some similarities to the development of the Mustang. It would come from a firm outside of the established fighter/high performance pool of manufacturers. It would be a self generated proposal to get outside of the limitations of government spec requisitions. For fuel efficiency it would be powered by a Merlin. The design would adopt a wing that departed from the orthodoxy allowing more efficient cruise/speed with a large volume. It would be single engined. It would have added thrust from the cooling system. It would be a ground up design.

 

[BarnOwlLover]

As I was about to point out, the Spiteful still on internal fuel had a range of only about 550 miles or so. Not quite enough for a worthwhile escort fighter or a dual role escort/interceptor fighter. Granted, it probably didn't (or may not have had) the CG/directional stability issues that Spitfires with the rear mounted fuel tanks tended to have when fill above a certain level.

I do agree that the best chance of this happening for the British prior to adopting the Mustang is indeed if such a thing sort of came out of left field. After all, that's how the Mustang sort of happened in the first place, and how we also got the Mosquito. I do agree that (especially in 1942) it'd probably have to be Merlin powered, be optimized for low drag flight and fuel efficiency, and if not using a radiator design that adds thrust (easy in concept, harder in practice), one that at least reduces drag.

 

[tomo pauk]

As I was about to point out, the Spiteful still on internal fuel had a range of only about 550 miles or so. Not quite enough for a worthwhile escort fighter or a dual role escort/interceptor fighter. Granted, it probably didn't (or may not have had) the CG/directional stability issues that Spitfires with the rear mounted fuel tanks tended to have when fill above a certain level.

Math does not add up for the 550 mile range on internal fuel if the rear tank is used.
Seafire 47, an aircraft draggier than the Spiteful, was doing 5-5.5 air miles per gallon at 160-170 kt (190 mph) between 20 and 25K ft. 5 AMPG x 178 imp gals = 890 miles, without allowances.
550 mile figure might hold true for a Spiteful without the rear tank, 5 AMPG x 120 imp gals = 600, without allowances.

 

[BarnOwlLover]

Only range figures I've seen for the Spiteful was 564 miles on internal fuel and 1315 miles with drop tanks (Old Machine Press' article on the Spiteful and Seafang). Neither of which is great for escort work. Not to mention that I believe that the Spiteful had similar internal fuel capacity to he Griffon powered Spitfires, which had similar range, the Griffon was a lot more fuel hungry than the Merlin. Ironically, the Spiteful was looked at as far as using he Merlin if he two-stage Griffons ran into trouble.

However, I'd bet that a Merlin Spiteful would've been a good deal lighter than the Griffon version, and probably less fuel thirsty.