Was a competitive pre-Hercules Bristol-powered single-seat monoplane fighter feasible?

[nuuumannn]

So you dream up the turret armed fighter concept.

To be fair to the idea, the Brits were putting turrets on almost every new aircraft spec in the mid to late 30s... Nonetheless, what did they know?

As for the Venom, Jeffrey Quill has much to say about it in his excellent book Spitfire A Test Pilot's Story (John Murray, 1983):

"The Venom was a sporting little aeroplane. it could not match up to the Spitfire's performance but it was doing around 325 mph at about 15,000ft. it was extremely manoeuvrable and delightful as an aerobatic aeroplane. Its big trailing edge flaps which came down to 90 deg produced a great deal of drag which killed any float during the flare-out for landing. One could put it down very accurately therefore on the exact spot required for landing (which was not so easy with the Spitfire). All this time I felt that it could use much more power with great advantage if only it was available."

" The Venom had some interesting technical features: for instance, engine cowling gills,gun heating and gun firing were all electrically operated as wellas the normal electrical services such as reflectorgunsight, navigation lights, cockpit illumination and so on."

"Another point of interest was that the whole engine hinged through 90 deg on ther ground allowing very ready access to the back of it for maintenance purposes, all connections being flexible. From the early performance trials which I carried out it was clear the Venom was breathing down the Hurricane's neck as far as maximum speed was concerned; I was very much fretting for more power from the engine but there seemed no chance of that in the immediate future."

 

[Kevin J]

To be fair to the idea, the Brits were putting turrets on almost every new aircraft spec in the mid to late 30s... Nonetheless, what did they know?

As for the Venom, Jeffrey Quill has much to say about it in his excellent book Spitfire A Test Pilot's Story (John Murray, 1983):

"The Venom was a sporting little aeroplane. it could not match up to the Spitfire's performance but it was doing around 325 mph at about 15,000ft. it was extremely manoeuvrable and delightful as an aerobatic aeroplane. Its big trailing edge flaps which came down to 90 deg produced a great deal of drag which killed any float during the flare-out for landing. One could put it down very accurately therefore on the exact spot required for landing (which was not so easy with the Spitfire). All this time I felt that it could use much more power with great advantage if only it was available."

" The Venom had some interesting technical features: for instance, engine cowling gills,gun heating and gun firing were all electrically operated as wellas the normal electrical services such as reflectorgunsight, navigation lights, cockpit illumination and so on."

"Another point of interest was that the whole engine hinged through 90 deg on ther ground allowing very ready access to the back of it for maintenance purposes, all connections being flexible. From the early performance trials which I carried out it was clear the Venom was breathing down the Hurricane's neck as far as maximum speed was concerned; I was very much fretting for more power from the engine but there seemed no chance of that in the immediate future."

More than a match for the Ki-27 in the Far East, Yes or No? Because if yes, then why did we buy Buffaloes an Mohawk. Maybe it could have given those Italian radial engined fighters a good bashing too.

 

[tomo pauk]

More than a match for the Ki-27 in the Far East, Yes or No? Because if yes, then why did we buy Buffaloes an Mohawk. Maybe it could have given those Italian radial engined fighters a good bashing too.

UK was buying the Buffaloes and Mohawks and whatnot because it didn't required UK industry to make them.
More Venoms = less Spitfires?

 

[hobbes154]

British were screwed because the Bristol engines were set up to have the exhaust ports on the front of the cylinder heads (Bristol poppet valves) or the front of the cylinders (sleeve valves) and you have to turn the exhaust 180 degrees and route it through the cylinder gaps to try to get exhaust thrust.

Was this fixed in the Centaurus? Or is it not that big a deal? Sea Fury doesn't compare too badly to the Corsair especially given the bigger engine diameter.

 

[Shortround6]

They bought (or inherited) Buffaloes and Mohawks because that was what was available.
Development (let alone production) of the Aquila engine and been abandoned in 1938 and the Bristol 143 twin engine test bed scrapped, Only 5 airframes ever flew with the Aquila engine and some of them used the same engine. The Venom was certainly interesting but it has a lot of mysteries. As does the Aquila engine.
Wiki in the entry for the Venom says the Aquila made 625hp but does not say at what altitude or what rpm. This seems rather high for 950 cubic in engine.
Top speed is given as 312mph at 16,500 which seems to rather a high altitude for engine that is described as "medium" supercharged. Remember definitions of what was medium and what was full supercharged (high altitude) changed rather quickly.
Lumsden is not the help it could be as he only has one entry for the Aquila and none of the figures come close to 625hp, however it looks like there is a type setting error in the charts at the back and all the figures are moved over a column? His figures may also be based on 73 octane fuel and not 87 octane.
Aircraft of Engines of the World, 1941 has a bit different figures like 600hp for take-off (no boost listed) and 540hp at 6,000ft as rated power (5 min max) which is also listed in "Aircraft Engines" by A. W. Judge 1941. as a civil rated Aquila IV(?).

More information would be appreciated.

 

[Shortround6]

Was this fixed in the Centaurus? Or is it not that big a deal? Sea Fury doesn't compare too badly to the Corsair especially given the bigger engine diameter.

engine on a B-25.

You could do it on the British engines, it just took a lot more work and baffling.

A late war or post war engine installation was a lot more complicated than an early war installation let alone a prewar one.

Every bend you put in a pipe and every foot of length is going to cost some amount of thrust. However sticking 14-18 individual lumps and bumps around the cowl is also going to cause some degree of drag. Also please note the B-25 pipes did absolutely nothing for moving air through the cowling to help cool the engine, Of course they weren't acting as engine heaters either
Getting all the conflicting requirements sorted out for the best compromise took some doing.

 

[hobbes154]

Maybe this should be its own thread, but how was the Zero Model 21 so fast (331mph) on 950hp, and why was the 1130hp Model 32 little faster?
(Yes, I admit to relying on Wiki numbers here, but they seem to be backed up e.g. Zero Model 21 Performance: Unraveling Conflicting Data.)

• The Sakae has a small diameter (45in) but not that much smaller than the Twin Wasp (48in). It's still a radial.
• Wing is large - 241 ft2 against 172 ft2 on the J22 or 161 ft2 on the Ki-44, even bigger than 236 ft2 on P-36/40.
• It was well streamlined but no real aerodynamic breakthrough comparable to "laminar flow" wings, a Mustang radiator or FW 190 radial installation?

 

[Kevin J]

Maybe this should be its own thread, but how was the Zero Model 21 so fast (331mph) on 950hp, and why was the 1130hp Model 32 little faster?
(Yes, I admit to relying on Wiki numbers here, but they seem to be backed up e.g. Zero Model 21 Performance: Unraveling Conflicting Data.)

• The Sakae has a small diameter (45in) but not that much smaller than the Twin Wasp (48in). It's still a radial.
• Wing is large - 241 ft2 against 172 ft2 on the J22 or 161 ft2 on the Ki-44, even bigger than 236 ft2 on P-36/40.
• It was well streamlined but no real aerodynamic breakthrough comparable to "laminar flow" wings, a Mustang radiator or FW 190 radial installation?

Reminds of the Hurricane I performance figures. Fresh from factory, 324 mph, repaired after battle damage, 306 mph. As tested in 1941 with 16 lbs boost, 335 mph. So yes, quite a variation. A 3% variation in performance was also allowed.

 

[Admiral Beez]

Maybe this should be its own thread, but how was the Zero Model 21 so fast (331mph) on 950hp, and why was the 1130hp Model 32 little faster?

IIRC, the Model 21 had no armour, radio or self sealing fuel tanks. The Model 32 had all these, which must have added weight.

 

[hobbes154]

IIRC, the Model 21 had no armour, radio or self sealing fuel tanks. The Model 32 had all these, which must have added weight.

Yes, but I was under the impression weight per se didn't count very much for max speed, given wing and frontal area etc.

 

[Admiral Beez]

The US, Japan, and Italy were able to build competitive fighters with 1,000 hp radials; that the UK didn't just means they didn't.

Looking back at this old thread leads me to wonder what the best British aerodynamics experts could have done if given the money and resources to develop a fast Perseus or Mercury powered fighter. I'd give the job to Petter, his Whirlwind was a study in streamlining.

 

[Shortround6]

You still wind up with a 2nd class fighter, or 3rd class depending on timing.
The Mercury had 82% of the power of a Merlin III several thousand feet lower.
It was just over 51in in diameter (1.3 meters).

You can streamline the crap out ot the rest of the airplane, you don't have enough power and the engine is too fat.

 

[ThomasP]

The Aquila AE.3S engine fitted to the Venom was an advanced model with a higher altitude rated supercharger (+25% impeller tip speed) than the previous models of Aquila, but only built in prototype form (a total of 3 engines). Its max rating was 3550 rpm at +5 lbs boost. I do not know what the HP was at this rating, what the full throttle altitude was, or if the above settings were for TO or at FT altitude. Given the AM Specification requirements for the ability to intercept a 200 mph+ aircraft at 15,000 ft I would assume that the full throttle altitude would be somewhere in the neighborhood of 15,000 ft.

 

[Kevin J]

The Aquila AE.3S engine fitted to the Venom was an advanced model with a higher altitude rated supercharger (+25% impeller tip speed) than the previous models of Aquila, but only built in prototype form (a total of 3 engines). Its max rating was 3550 rpm at +5 lbs boost. I do not know what the HP was at this rating, what the full throttle altitude was, or if the above settings were for TO or at FT altitude. Given the AM Specification requirements for the ability to intercept a 200 mph+ aircraft at 15,000 ft I would assume that the full throttle altitude would be somewhere in the neighborhood of 15,000 ft.

Problem is that even a Hurricane I with the big bulky Vokes tropical filter was faster than all the British radial engine SE SS fighters. Only the Buffalo I, Martlet and Mohawk IV had comparable speeds. Speeds competitive with the Hayabusa and Reisen, superior to the Ki-27 and A5M4.

 

[Admiral Beez]

You can streamline the crap out ot the rest of the airplane, you don't have enough power and the engine is too fat.

Hmm.... I see what you mean, we need a Bristol engine that's more like the Nakajima Sakae's 45 in. diameter. What was the point of eliminating the OHVs and valve train if your engine is still fat?

The 45.25in diameter Bristol Taurus 1.25in wider than the Sakae, maybe that's where we start? It got the Gloster F.9/37 to 360 mph in twin form.

 

[Kevin J]

Hmm.... I see what you mean, we need a Bristol engine that's more like the Nakajima Sakae's 45 in. diameter. What was the point of eliminating the OHVs and valve train if your engine is still fat?

The 45.25in diameter Bristol Taurus 1.25in wider than the Sakae, maybe that's where we start? It got the Gloster F.9/37 to 360 mph in twin form.

No development potential. Better to buy the Buffalo and Mohawk as an interim measure.

 

[Admiral Beez]

Maybe this should be its own thread, but how was the Zero Model 21 so fast (331mph) on 950hp, and why was the 1130hp Model 32 little faster?

Weight. There was nothing under 4,000 lbs. that could match the Zero.

2nd best fighter under 4,000 lbs (empty)?

 

[tomo pauk]

Maybe this should be its own thread, but how was the Zero Model 21 so fast (331mph) on 950hp, and why was the 1130hp Model 32 little faster?
(Yes, I admit to relying on Wiki numbers here, but they seem to be backed up e.g. Zero Model 21 Performance: Unraveling Conflicting Data.)

1130 HP was achieved at lower altitudes, that was partially a function of the Sakae 20 series receiving a 2-speed S/C (earlier versions were with 1-speed S/C, there was no low gear). With S/C in high gear, the engine power was ~1050 CV at ~18000 ft (vs. ~950 CV at 13800 ft). Please note that 20 series were also making better RPM, and were outfitted with bigger impeller (12 in vs. 11.4 in diameter), that gained not just a bit more power, but it was also achieved at considerably greater altitude, almost matching what the 2-stage supercharged R-1830 did.
The speed difference above 19000 ft was probably around 20 km/h, Zeke 11 and 21 (have had 'old' engines) vs. 22 ('new' engine) - comparable as what was done with Spitfire I vs. Spitfire V. Later Zekes received better exhausts for more speed, that was later defeated by having more firepower (= more drag) and introduction of protection for pilot and fuel (= more weight).

• The Sakae has a small diameter (45in) but not that much smaller than the Twin Wasp (48in). It's still a radial.
• Wing is large - 241 ft2 against 172 ft2 on the J22 or 161 ft2 on the Ki-44, even bigger than 236 ft2 on P-36/40.
• It was well streamlined but no real aerodynamic breakthrough comparable to "laminar flow" wings, a Mustang radiator or FW 190 radial installation?

Wing was small vs. F4F and Hurricane, there was no fat belly nor the fat nose (that can accept the 55in wide R-1820 without breaking the sweat) like on the F4F. No airbrake-type radiators as in Hurricane, nor as thick the wing (both in absoulte and relative terms). No exhausts sticking it the airstream like on Hurricanes, either.
Kinda shows that there is more than one way to skin a cat.

 

[gjs238]

Was a competitive Hercules-powered single-seat monoplane fighter ever feasible?
Or possible, even on a non-British air frame?

 

[Admiral Beez]

Was a competitive Hercules-powered single-seat monoplane fighter ever feasible? Or possible, even on a non-British air frame?

I don't see why not, it's an >1,200 hp engine, pretty much like any other. It made the Beaufighter Britain's second best twin engined strike bomber, just under the superlative Mosquito. The Gloster f.5/34, shown below seems the likely candidate for a Hercules retrofit, and I'm sure it's been discussed here before.

But Britain had the Merlin and Griffon, cancelling out any need for a Hercules fighter. The only reason the Hercules' successor the Centaurus found its way into single seat fighters was that the Sabre engine was troublesome.

To give an example of what the front end of a Hercules single engine fighter might look like, here's Folland's testbed fitted with a Hercules.

Plus a Fairey Battle fitted with a Hercules.