Westland Whirlwind revisited

[NevadaK]

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.

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.

Going completely off timeline, I could imagine an argument where a turboprop replacement for the Peregrine would be a promising avenue.

 

[Admiral Beez]

Going completely off timeline, I could imagine an argument where a turboprop replacement for the Peregrine would be a promising avenue.

How about a pair of RR Derwents? Like the engine swap on the SAAB 21 from piston to jet in the SAAB 21R.

At 33ft long, the Heinkel He 280 was about the same size as the >32ft long Whirlwind. The jet-powered Whirlwind's lack of radiators in the wings, plus the Whirlwinds greater wingspan (45 ft vs. >39 ft on the Heinkel) may allow for more internal fuel.

The Whirlwind's designer WE Petter did design many of Britain's best jet aircraft, including the Canberra, Lighting and Gnat. Let's see if he can beat Gloster to the punch.

 

[Schweik]

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

Yes I see your point. I was thinking a center wing-section fuel tank might allow for a single large tank which goes through the wing and the bottom of the fueselage, which would give more space for another 20% or so of fuel, like the wing tanks on the P-40. But I'm not sure from looking at that photo if there would be room for that.

 

[pbehn]

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.

.

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.

 

[stona]

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.

If we stick with the Peregrine engines, they, along with all the other flight components, were provided to Westlands by May 1938. The wings of the first prototypes, complete with engines, fuel tanks, radiators etc., were completed in July.

In June 1938 the ACAS (Sholto-Douglas at the time) told Freeman that deliveries of the Whirlwind might start by June 1940, so just barely in time to begin its induction into service for the Battle of Britain. Douglas said at the time that this seemed '...an unnecessarily long time to produce an aircraft designed early in 1936' and he may have had a point. The question is how could this timeline be speeded up?

We would need to reduce the delays that kept creeping in as the aircraft was developed. We could save some time by NOT adopting the Exactor throttle controls, there must have been a reason these replaced the original mechanical linkages but I do not know what they were and maybe we could do better.

The next delay was a failure in the casting of the inboard wall of one of the fuel tanks, this was finally rectified at the end of August, because the entire wing had to be dis-assembled, but we've still got more than a year until the war begins.

Etc. etc. and this is before we begin to deal with the problems I listed a while back that dogged the aircraft's entry into service.

There were arguments for involving another company in Whirlwind production. Westland was based at Yeovil, frankly, in the middle of nowhere. It had a limited recruitment area and that was largely agricultural.

Yeovil today:

There were few opportunities to sub-contract the manufacture of components to other companies. In August 1938 Westland had a productive work force of just 726, a fifth of Bristol's, and was sub-contracting only 13% of the man hours involved in Lysander production. Maybe some improvements could be made here?

The issue is that the Air Ministry had suffered a serious loss of Spitfire production because Supermarine had made so many changes after sub-contracting began. The Ministry was keen to avoid such a failure and recommended that other companies should only be involved AFTER Westland could produce final production drawings, which meant after the company itself began producing the aircraft.

On the bright side, there were changes in the ownership of Westland at the end of 1938, and this led, theoretically at least, to an increase in resources. Westland also acquired the old Petters engine factory after that business was sold, so they had more room too.

Of course, these are just some of the issues affecting the entry into production of a new aircraft in the boring real world and I would be interested to know how we might have got the Whirlwind into several Fighter Command squadrons by the summer of 1940 in an alternate universe, assuming we can overcome the next hurdle...Dowding didn't want it, but maybe we could convince him by improving the service ceiling and altitude performance? That's something that needs to be done between late 1938 and mid 1940, so time is of the essence!

Anyway, answers and suggestions on a postcard to the usual address. Anyone suggesting a Merlin powered version will be sent to see the Headmaster

 

[pinsog]

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????

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)

 

[Schweik]

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)

 

[pinsog]

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)

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.

 

[Schweik]

The P-40 did go into the wind tunnel for a bit after initial tests were showing too slow

 

[Admiral Beez]

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,

Enough horsepower can overcome any drag.

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.

 

[NevadaK]

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)

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 Tomio Kubo. 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.

 

[pinsog]

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.

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???

 

[MikeMeech]

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)

Hi

While the Ki 46 is a good aircraft and a difficult target it is clear from those that were shot down by Spitfires that they were done by non-stripped down Mk.Vc and Mk. VIIIs. There has been mention of Plt. Off A H Wittridge of 155 Sqn. flying a 'stripped down' Spitfire VIII (the four MGs removed plus the rear-view mirror and ballast) this is identified as LV678, DG-C on pp.281-282 of 'Air War For Burma' by Christopher Shores, and associated with a claim on 5 Nov. 1944 for a Ki 43 not Ki 46. Wittridge was associated with a claim for a Ki 46 on 25 Sept. 1944, along with Flt Sgt P G Lunnon-Wood flying aircraft 'G' and 'F' of 155 Sqn. (p.265 of previous source). It appears from this he was flying a different aircraft than the later 'stripped down' 'C'. There is no mention of 'G' being 'stripped down' in the source. If there is a source giving details that the Spitfires used to shoot down the Ki 46 please let us know.

Mike

 

[Schweik]

They shot down several of those ki-46's with p-40s

 

[Schweik]

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. The ki 46 though didn't do much well except go in a straight line apparently.

 

[yulzari]

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.

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.

 

[Shortround6]

Cotton got a Blenheim up to 290mph or a bit more (not 300mph) and that required quite a bit of hand finishing work.
Also Cotton's Blenheim was not carrying a gun pack.

The Ki 46 is quite interesting.
Now it you could just get Mitsubishi engines from mid 1941 in service in Britain at the same time or earlier you might have something.

From Wiki; " The engines, two Mitsubishi Ha-26s, were housed in close fitting cowlings................... The first prototype aircraft, with the designation Ki-46, flew in November 1939...........Tests showed that the Ki-46 was underpowered, and slower than required, only reaching 540 km/h (336 mph) rather than the specified 600 km/h (373 mph). .........................To solve the performance problems, Mitsubishi fitted Ha-102 engines, which were Ha-26s fitted with a two-speed supercharger, while increasing fuel capacity and reducing empty weight. This version, designated Ki-46-II, first flew in March 1941. It met the speed requirements of the original specification, and was ordered into full-scale production, with deliveries starting in July."

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.

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.

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.

 

[wuzak]

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.

I'm guessing the work required to fit R-1830s would be similar to that needed to fit Merlins. That is, a lot.

 

[Shortround6]

The R-1830 weighed about 350lbs more than a Peregrine. This is for the two speed version. Granted there is no radiator or coolant. What kind of games have to played to keep the CG in the proper place I don't know, The radiators being either on on nearly on the CG.

The P & W R-1830 two speed offers about 13% more power at nearly the same altitude (I am not going to argue over 500ft out of 15,000) as the Peregrine. so either the installation causes less than a 13% increase in drag or performance at altitude falls. Please note that the 14,500ft rating is at 2700rpm and many charts limit most R-1830s to 2550rpm in high gear.

 

[NevadaK]

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???

Kubo's follow up design, the Ki-83 gives you an idea what that would look like.