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Whirlwind Mk.II


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#1 fw190d11

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Posted 04 May 2007 - 12:14 PM

This info was originally posted on another board many months ago. (Might have been ww2aircraft.net, dont really remember.) I repost it here for discussion and opinions.

The Whirlwind was probably actually too neat an airframe for its own good. A twin engine fighter with less frontal area than a Hurricane was an impressive feat of aerodynamics.

The Whirlwind had a few problems:
1. The reliability and slow development of the Peregrine (power, supercharging, etc.), combined with its small displacement.
2. The artificially shortened combat radius due to a lack of cross-feed fuel tanks (a really stupid design error, my respect for Teddy Petter notwithstanding).
3. Small size and complex internal structure meant that further development was quite difficult. Certainly not in the same class as the P-38.
4. The cost and long manufacturing time of the fighter and the prevailing RAF attitude that day fighters were single-engine machines. The Whirlwind was regarded as something of square peg wanting a round hole: it did plenty of jobs, but nothing that something did better. In the 1941 period the RAF wanted more squadrons and the slow build pace of the Whirly didn't help.
5. The poor performance of the Peregrine engine above 18,000 feet.

There was a proposed Whirlwind Mk II which would of rectified some of the major weaknesses in the Mk I. Cross-feed fuel tanks would of been installed, increasing range by about 30%. A 45 gal rear fuselage tank and an additional 25gal forward fuselage tank were to have fitted, adding even more range. The Peregrines were to go to 100 octane fuel (instead of the 87 octane they ran on for their service life) and be boosted from 885hp to 1010 hp. New 'high activity' propellers were to have been fitted, along with a new automatic electric system to control prop pitch and rpm (the old automatic hydraulic system fitted to the Whirlwind being much despised by the pilots and apparently quite dangerous in some circumstances).

Calculations by the Westland design team predicted a 400 mph + top speed at around 18,000 feet, as well as significantly improved time to height performance. There was a very interesting article in 'The Aeroplane' several months back about the design.

It's that last sentence I find most interesting. "The Aeroplane" is some sort of newsletter or magazine over in England. Do any of our English members recognize this...and more important...might they be able to find that article?!? [8D] Based on what I remember of the time/date of the post, said article cant be more than two years old, tops.

Any takers? [^]



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#2 PMN1

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Posted 04 May 2007 - 04:27 PM

Some information i got sent a while back

Called "Developing the Whirlwind" the bulk of the article just covers the run-of-the mill stuff about the F37/35 and the design of the Whirlwind. It is stresses that the decision to drop the Peregrine was made by Rolls - Royce simply so that they could concentrate on the Merlin and Griffon - Rolls Royce are quoted as saying "Further production of Peregrines would have entailed the loss of two Merlins for every Peregrine".

What is of particular interest is the revelation that before it was dropped a "developed" version of the Peregrine was mooted by Rolls-Royce, giving a power increase of 15% - Not told of the decision to axe the Peregrine, Westland designed a "Whirlwind Mk II" around the more powerful engine- It made use of a redesigned nose that had been test flown on an existing Whirlwind - It was lengthened to allow the cannons to be grouped in a line with larger 120 round magazines for each - there was a room for an extra fuel tank in the nose giving an increase in fuel of 20%. - The extra power of the engines was calculated to give an increase in top speed (at 20,000 ft) to 422 mph.

The extra power of the engines would have decreased the take-off run from 600yds to 540 (the original Whirlwind was at a disadvantage in being unable to use some of the RAFs smaller airfields) - A Mk II Whirlwind would also have fixed the problem with the fuel systems on both engines being separate (with fuel from one unable to be diverted to the other in the event of an engine failure).

The performance estimates for the new design were... (These figures were produced in May 1940)

Top speed (20,000 ft) 422 mph (an increase from 390 mph on the "Mk I" which was acheived at a lower altitude of 15,000 ft)
Range - 900 miles (on internal fuel)

The article gives a full performance estimate for the Mark II with top speeds at various altitudes compared with the "Mk I" Whirlwind - Rate of climb was particularly expected to improve - reaching 30,000 ft in 12.8 minutes compared to 24 minutes for the Mk I.

Now compare that with the performance of a mid -to-late-war Lockheed P-38J Lightning with twin Allison 1,425 hp engines.

Top speed- (25,000 ft) 414 mph
range - 475 miles on internal fuel (of course it usually flew with drop tanks)

The only fly in the ointment is the fact that the Peregrine had only a single speed supercharger, so it's service ceiling, and performance at extreme altitude would not have been as good as the 2 speed, 2 stage Merlins.

Re the Whirlwinds top speed - The top speed of the Whirlwind MK1 that went into production was 360 mph at 15.000 ft - However in the Spring of 1940 an entire Whirlwind was mounted in Farnborough's wind tunnel to see if any simple improvements could cut down drag - These identified some areas that could be improved and it was considered that an additional 15 - 20 mph would be gained. At the same time the replacement of the existing engine radiators with the new "film" type radiator which had much less drag would also push up the top speed*. - These were improvements that did not merit the use of a new Mark number but were expected to be introduced on future production batches of the Mk I - These and other minor improvements give rise to the figure of a top speed of 390 mph at 15,000 ft for the Mk I when compared with 422 mph at 20,000 ft expected for the Mk II. So it must be stressed that the figure of 390 mph was not the top speed of any of the Whirlwinds that actually saw service.

The armament combinations schemed for the Whirlwind Mk II were...

4 Hispano cannon with 60 round drums (as per Whirlwind I)

4 Hispano cannon with belt feed in horizontal line with 120 Rounds each (test flown in Whirlwind L6844)

4 Hispano cannon with Belt feed in Horizontal line with 120 rpg and also 3 Browning 303 machine guns also mounted in the nose with 400** rpg

12 Browning 303 machine guns with 500** rpg ( A full mock-up of this was built by Martin Baker)

Single 37 mmm cannon (test flown in Whirlwind L6844)

Again- all this info is in "Whirlwind- The Westland Whirlwind Fighter" by Victor Bingham.

* The radiators used in the Whirlwind MK I were not a particularly good design and did not even make full use of the full cooling airflow available to them - Much of the "unreliability" levelled at the Peregrine engine was not due to the engine itself but to the inefficent radiator design used in the Whirlwind. The improved Morris film radiator would have not only improved the speed of the Whirlwind but also solved a lot of the engine problems (which do not seem to have been that great anyway).
**remember that Spitfires and Hurricanes only carried about 300 rounds per gun





#3 Ricky

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Posted 04 May 2007 - 09:11 PM

Very interesting, thanks PMN1!:)

However, I would be a little cautious of comparing projected performance figures to actual performance figures* - we know how far they could be wrong back in the 1940s!


*Especially against the P-38... you know who will read this...[}:)]

#4 Tony Williams

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Posted 04 May 2007 - 09:19 PM

quote:Originally posted by PMN1


Single 37 mmm cannon (test flown in Whirlwind L6844)

This is not quite correct. The photos of this installation clearly show that the gun fitted was a single Hispano 20mm, complete with Recoil Reducer (muzzle brake). It seems that the mounting was designed for a larger calibre gun, but there wasn't one available so they fitted a Hisso instead.

There is some mystery over what the intended 37mm gun might have been. The only one available in Britain at the time (AFAIK) was the old WW1 COW gun, of which very few were available and for which the ammo was very old. It would have made far more sense to fit a Vickers 40mm S gun, as installed in the Hurricane IID. This was in fact proposed but never implemented.

Tony Williams
Homepage: http://www.quarry.nildram.co.uk




#5 fw190d11

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Posted 04 May 2007 - 10:23 PM

quote:There is some mystery over what the intended 37mm gun might have been. The only one available in Britain at the time (AFAIK) was the old WW1 COW gun, of which very few were available and for which the ammo was very old. It would have made far more sense to fit a Vickers 40mm S gun, as installed in the Hurricane IID. This was in fact proposed but never implemented.


Tony, might they have bought M2s(?) from the US? They would have known about them from their dealings with the Airacobra.

A "Whirlybomber" with twin 37s would have made Rodeos and Circuses that much more exciting! :D

#6 fw190d11

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Posted 04 May 2007 - 11:05 PM

Should have combined this with other reply.:(

quote:Very interesting, However, I would be a little cautious of comparing projected performance figures to actual performance figures* - we know how far they could be wrong back in the 1940s!


Here's a formula I was told of, to calculate increase in HP vis a vis increase in speed: Take the cube root of the ratio of HP Increase. Mutiply this by Original Speed to get Boosted Speed.

{cubert[N/F]x S}= B
N=new HP
F=original HP
S=original Speed (kph)
B=new Speed (kph)

Applying all this we see an increase in Perigine power to 1017hp produces a new speed of 377mph. Then add in new nose and aerodynamically improved radiators and we get a speed of around 390-400mph tops. Not a match for the P-38, but enough in 1941 to give Me-109Fs a shock! [8D] I'd fly it and be happy.

#7 Tony Williams

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Posted 05 May 2007 - 01:53 AM

quote:Originally posted by fw190d11

quote:There is some mystery over what the intended 37mm gun might have been. The only one available in Britain at the time (AFAIK) was the old WW1 COW gun, of which very few were available and for which the ammo was very old. It would have made far more sense to fit a Vickers 40mm S gun, as installed in the Hurricane IID. This was in fact proposed but never implemented.


Tony, might they have bought M2s(?) from the US? They would have known about them from their dealings with the Airacobra.

The M4, you mean. It's just possible, I suppose. The British did carry out some ground firing tests of the gun at one time, but I'm not sure of the date of that. However, given the hazardous supply situation from the USA, and the fact that the US was reserving most weapon production to build up its own armed forces, I think it is unlikely.

Tony Williams
Homepage: http://www.quarry.nildram.co.uk


#8 Trexx

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Posted 05 May 2007 - 02:10 AM

Pictures!

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Beefy little hot-rod! Sweet!

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#9 curmudgeon

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Posted 05 May 2007 - 11:47 AM

quote:Originally posted by fw190d11


Calculations by the Westland design team predicted a 400 mph + top speed at around 18,000 feet, as well as significantly improved time to height performance. There was a very interesting article in 'The Aeroplane' several months back about the design.

It's that last sentence I find most interesting. "The Aeroplane" is some sort of newsletter or magazine over in England. Do any of our English members recognize this...and more important...might they be able to find that article?!? [8D] Based on what I remember of the time/date of the post, said article cant be more than two years old, tops.

Any takers? [^]

'Aeroplane' (monthly) is a widely distributed magazine that has been running since 1973. It is styled on 'The Aeroplane', a weekly, which ran from 1911 to 1968. It focuses on older aircraft and republishes many of the old technical drawings that were a feature of 'The Aeroplane' and its rival 'Flight'. A real feature is the refurbishment (nah! rebuilding) of recovered aircraft. There is a heavy focus on WWII, but a recent issue had an interview with Britain's oldest man who was involved with spotter planes at the battle of Jutland! Another recent interviewee was the last aircrew survivor of the Taranto raid. US veterans also feature frequently (latest issue I saw, a B26 pilot who had a run in with Me262s over Bavaria in the last month of the war).
Question to our American members - is 'Aviation History' still running?

#10 Groggy

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Posted 07 May 2007 - 04:24 PM

quote:Originally posted by fw190d11

This info was originally posted on another board many months ago. (Might have been ww2aircraft.net, dont really remember.) I repost it here for discussion and opinions.

The Whirlwind was probably actually too neat an airframe for its own good. A twin engine fighter with less frontal area than a Hurricane was an impressive feat of aerodynamics.

The Whirlwind had a few problems:
1. The reliability and slow development of the Peregrine (power, supercharging, etc.), combined with its small displacement.
2. The artificially shortened combat radius due to a lack of cross-feed fuel tanks (a really stupid design error, my respect for Teddy Petter notwithstanding).
3. Small size and complex internal structure meant that further development was quite difficult. Certainly not in the same class as the P-38.
4. The cost and long manufacturing time of the fighter and the prevailing RAF attitude that day fighters were single-engine machines. The Whirlwind was regarded as something of square peg wanting a round hole: it did plenty of jobs, but nothing that something did better. In the 1941 period the RAF wanted more squadrons and the slow build pace of the Whirly didn't help.
5. The poor performance of the Peregrine engine above 18,000 feet.

There was a proposed Whirlwind Mk II which would of rectified some of the major weaknesses in the Mk I. Cross-feed fuel tanks would of been installed, increasing range by about 30%. A 45 gal rear fuselage tank and an additional 25gal forward fuselage tank were to have fitted, adding even more range. The Peregrines were to go to 100 octane fuel (instead of the 87 octane they ran on for their service life) and be boosted from 885hp to 1010 hp. New 'high activity' propellers were to have been fitted, along with a new automatic electric system to control prop pitch and rpm (the old automatic hydraulic system fitted to the Whirlwind being much despised by the pilots and apparently quite dangerous in some circumstances).

Calculations by the Westland design team predicted a 400 mph + top speed at around 18,000 feet, as well as significantly improved time to height performance. There was a very interesting article in 'The Aeroplane' several months back about the design.

It's that last sentence I find most interesting. "The Aeroplane" is some sort of newsletter or magazine over in England. Do any of our English members recognize this...and more important...might they be able to find that article?!? [8D] Based on what I remember of the time/date of the post, said article cant be more than two years old, tops.

Any takers? [^]



Hi Folks, PMN1, fw190d11,

Do you have the drawing of the Peregrine from "Whirlwind- The Westland Whirlwind Fighter" by Victor Bingham. I am sure it is different to the wooden model of what I think is a Peregrine Engine at R-R black Museum at Derby. The backend appears to have a very big “supercharger” with intercooler stuck on? The engine block looks the same as a battered crashed Peregrine with out supercharger. I do not have an internet connection at home but I have two photographs of the model I will ask some one to help post them, then we can share our opinions of the model and how they compare. I guess the engine was originally destined for the Whirlwind?


#11 conrad

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Posted 11 May 2007 - 05:32 AM

I have been fascinated by the Whirlwind, the best fighter the RAF never had in the war. I was suprised most about the Perigrine. In wartime Britain everything was under tight government control, but it appeared the Rolls Royce was allowed to undermine a fighter project off its own bat. Even though Rolls Royce had a lot of political influence it is suprising it was allowed such latitude.

#12 ChrisMcD

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Posted 11 May 2007 - 06:05 PM

Hi Conrad,

It was not just Rolls, there was a general consensus that military aircraft suddenly needed to have much more powerful engines to cope with all the extra kit they had to carry.

So Bristol shifted from the Aquila and Perseus to the Taurus and Hercules

http://en.wikipedia..../Bristol_Taurus

And Napier dropped work on the Dagger and switched to the Sabre.

Rolls were trying to share development between the Peregrine and the Vulture - but the Vultures lubrication problems were not solvable in the timescale that Rolls were working to. So the Peregrine suddenly had to justify it's development on it's own account

http://en.wikipedia....Royce_Peregrine

With the Whirlwind as it's only production outlet and the huge demand for Merlins it is hardly surprising that it lost out. Much as I respect Petter, he should have made the airframe more adaptable from the outset. Just look at the way so many other aircraft of the same period swopped engines around because their deisgners were well aware of constantly shifting supplies and priorities (ie Beaufighter, Lancaster, Wellington, etc.)

Also, bear in mind that the Merlin had a very troublesome early development period and that must have taken up the vast bulk of Rolls' development engineers for the critical period.

Finaly, before Hooker took over, I get the feeling that Rolls were overstretched on supercharger development. The fact that the two stage Merlin 61 supercharger used the Vulture supercharger as it's primary compressor argues that they were forced to cut corners wherever they could!

My suspicion is that it was the problems of supercharger development that really put the kybosh on the Peregrine

#13 simon

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Posted 11 May 2007 - 07:55 PM

quote:Originally posted by conrad

I have been fascinated by the Whirlwind, the best fighter the RAF never had in the war.


I've always understood that the Whirlwind was not without its shortcomings. IIRC it was supposed to be a quite tricky aircraft to fly, and was quite demanding when it came to the quality and length of runways having quite a high landing speed. This was one serious factor limiting it's production since it handicapped the deployability of the type outside of the UK where conditions would be less ideal.

Arguably other types which were less demanding on pilots and ground conditions were probably better choices.

#14 Lightning

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Posted 11 May 2007 - 08:55 PM

Hi PMN1,

Quoting you:

quote:Now compare that with the performance of a mid -to-late-war Lockheed P-38J Lightning with twin Allison 1,425 hp engines....
range - 475 miles on internal fuel (of course it usually flew with drop tanks)


That 475 miles refers to the P-38J's range at high altitude and high cruising speed. At 10,000 feet, the "J" had a range of between 800 and 1200 miles on internal fuel, depending on the cruising speed selected. The very last "L" models had an even greater internal fuel capacity than the "J"s.

Regards,
Lightning

P.S.
Even though he's correct regarding the accuracy of projected performance figures, don't listen to Ricky. He's a troublemaker! :D




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