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The Peregrine developed 0.68hp/cuin. Projecting development to the best performing late war engines (.9hp/cuin) the Peregrine only develops 1100hp - 1200hp. Thats still fairly low for a mid war high performing fighter. In addition, you have increased fuel consumption without addressing the limited fuel capacity/short range.I like this, and if we can keep the Peregrine's dimensions and weight down, we might have an engine for a lightweight, smaller single-engined fighter. I'd want to offshore the engine production away from RR though (and likely the aircraft as well), as they clearly don't have the capacity to produce more than one engine type at a time. The Griffon came on board after years of expansion.
How about a pair of RR Derwents? Like the engine swap on the SAAB 21 from piston to jet in the SAAB 21R.Going completely off timeline, I could imagine an argument where a turboprop replacement for the Peregrine would be a promising avenue.
So, swap the fuel tanks from the outer wings to the inner wings and the radiators from the inner wings to the outer wings?
Westland Whirlwind cutaway
But there lies the issue, two peregrines have about the same output as a Griffon or very late Merlin. The first Griffon engine Spitfire flew in November 1941. The Whirlwind wanted to be a Hornet, which flew in July 1944 and was a beast.The Peregrine developed 0.68hp/cuin. Projecting development to the best performing late war engines (.9hp/cuin) the Peregrine only develops 1100hp - 1200hp. Thats still fairly low for a mid war high performing fighter. In addition, you have increased fuel consumption without addressing the limited fuel capacity/short range.
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But really, the only thing I want to change on the Whirlwind is its entry into service date. So we need to make changes to its development path and timing. Do that, and we'll have a half dozen squadrons in service by the BoF.
I have no idea how radial engines would have worked on the Whirlwind, but the initial response with using radials on a twin fighter, like the F5F Skyrocket is 'too much drag'. Yet the Japanese Ki46 was essentially immune to interception until at least mid war, even P38's and stripped down Spitfires had great difficulty catching it. The Ki46-II had 2 speed radials with 1080 hp at takeoff and 1055 hp at 9,200 feet, 44 inches in diameter and yet it was capable of 375 mph+ at 19,000 feet. As small as the Whirlwind is, if it could hold a pair of 2 speed 1830 P&W it should be very fast at any altitude for that time of the war. (I'm not at all sure it was big enough to handle them though)Nobody wants to talk about the absolutely bad performance such a plane would have????????
It seems I am one of the resident contrarians,
The Italian plane managed 311mph at 16,404 ft using engines that gave 840hp at 12,500ft. Other sources may differ on power/altitude.
The Fiat engine was only 46.8in in diameter with a frontal area of 11.9 sq ft. The plane carried a pair of 12.7mm machine guns.
Suggested engines seem to be.
The Perseus X ? 750hp for take-off and 880 hp at 15,500ft , 52in in diameter, frontal area 14.7 sq ft. again sources differ on diameter.
The Mercury....725hp for take-off and 840hp at 14,000ft. 51.5in diameter, frontal area 14.5 sq ft.
Taurus less said the better.
Cyclone 9? 1200hp for take-off, 1000hp at 14,000ft, 55.1in diameter and 16.6 sq ft of frontal area.
Twin Wasp? 1200hp for take-off 1050hp at 13,100ft 48.1in diameter 12.6 sq ft frontal area. around 1460lbs for the two speed single stage engine.
None of the these engines provide any exhaust thrust, at least not at this time or with existing cowlings. Not that the Peregrine in the Whirlwind got much in the way of exhaust thrust with the exhaust shrouds/manifolds it used.
Using British radials gives you a total dog of an aircraft and swapping in the American engines comes in late in the game.
The P-36 had about 22% more drag than an early P-40 all due to the radial engine (and loss of exhaust thrust?) and you guys want to hang TWO high drag radials on a small plane????
And I agree with that as well, the Zero was one slick machine, had to be to perform like it did with a 950 hp engine. As I have pointed out, the P36 and P40 both could have used a good amount of time in a wind tunnel.That is a fair point... I think Shortround was pointing out some issues with the ducting and farings on early radial engines in the Anglo-American sphere (1940-42 ish)
Enough horsepower can overcome any drag.I have no idea how radial engines would have worked on the Whirlwind, but the initial response with using radials on a twin fighter, like the F5F Skyrocket is 'too much drag'. Yet the Japanese Ki46 was essentially immune to interception until at least mid war,
Greetings Pinsog,I have no idea how radial engines would have worked on the Whirlwind, but the initial response with using radials on a twin fighter, like the F5F Skyrocket is 'too much drag'. Yet the Japanese Ki46 was essentially immune to interception until at least mid war, even P38's and stripped down Spitfires had great difficulty catching it. The Ki46-II had 2 speed radials with 1080 hp at takeoff and 1055 hp at 9,200 feet, 44 inches in diameter and yet it was capable of 375 mph+ at 19,000 feet. As small as the Whirlwind is, if it could hold a pair of 2 speed 1830 P&W it should be very fast at any altitude for that time of the war. (I'm not at all sure it was big enough to handle them though)
I don't know how much top speed would have dropped, weight doesn't affect top speed like it does climb and turn. Think if he had access to 1830 P&W with turbochargers on the Ki46. Well over 400 mph???Greetings Pinsog,
I had to go look at the Ki-46. Its remarkable that it had greater wingspan (+3'), length (+4'), and wing area (+100sf) than the Whirlwind and yet perform so similarly. My guess is that if the Ki-46 were more heavily constructed and armored some of that performance would tail off, but you make a fair point about radial engines being an option, provided enough time was spent perfecting the aerodynamics.
As an aside, reading the wiki post on the Ki-46 got me interested in the designer Tom Kubio. After the war he didn't have much opportunity to work on aircraft, but he stuck with Mitsubishi (after the forced post war break up) and ultimately ended up in charge of Mitsubishi Motors. He was a talented designer and one wonders what would have happened had he been able to remain in his chosen field.
HiI have no idea how radial engines would have worked on the Whirlwind, but the initial response with using radials on a twin fighter, like the F5F Skyrocket is 'too much drag'. Yet the Japanese Ki46 was essentially immune to interception until at least mid war, even P38's and stripped down Spitfires had great difficulty catching it. The Ki46-II had 2 speed radials with 1080 hp at takeoff and 1055 hp at 9,200 feet, 44 inches in diameter and yet it was capable of 375 mph+ at 19,000 feet. As small as the Whirlwind is, if it could hold a pair of 2 speed 1830 P&W it should be very fast at any altitude for that time of the war. (I'm not at all sure it was big enough to handle them though)
Sidney Cotton tried just that with a stripped down special finish Blenheim for PR but it was still too short on speed to prevent interception so he turned to the Spitfire.I'd like to see a Bristol Blenheim fighter, stripped down, streamlined, and see what it could do with its twin Mercuries in 1938-39.
The first engines used were 44in in diameter and 28 liters The Ki-46 III got larger engines of 48in diameter and 32 liters. The Perseus engines were 52in diameter according to some sources, others say more but 52in is fine for this discussion as the Perseus has almost 40% more frontal area and less power than the engines fitted to the Ki-46 prototype.I think the ki-46 is a good point of comparison for the whirlwind and it does show that a small radial engine can indeed be a part of the package of a very fast plane.
That is the British problem with the radial Whirlwind scenario, The British do not have a small diameter radial available no matter how light the engine may be.
The American R-1830 is in the ballpark at 48in in diameter but the R-1830 is heavy (just under 1500lbs with two speed supercharger) and performance at altitude is not very good, even with a two speed supercharger, 1000hp at 14,500ft for the two speed engine in high gear.
Kubo's follow up design, the Ki-83 gives you an idea what that would look like.I don't know how much top speed would have dropped, weight doesn't affect top speed like it does climb and turn. Think if he had access to 1830 P&W with turbochargers on the Ki46. Well over 400 mph???