Westland Whirlwind - Peregrine NOT GUILTY m'lud

[Folkbox1]

Prompted by a comment from the We Have Ways.. history podcast a search on t'net revealed that the problem with the Whirlwind was not the engine but the propellers.  Turns out they were not the same as fitted to the prototype, were too thick and caused too much drag at high speeds/altitude.  The constant speed unit couldn't adjust the angle of the blades to compensate enough so power and performance dropped off.  Admittedly, merlins would probably have had enough power to compensate but if the Whirlwind had the same props as fitted to the prototype the Peregrine would have been sufficient.

 

Who knew?

[TallBlondJohn]

Here's an article on Hush-Kit detailing various aspects of the Whirlwind, including the propeller issue. IIRC it was this article that the boys at We Have Ways read and reported - I know they follow HK:

 

https://hushkit.net/2023/07/22/top-10-advanced-features-of-the-westland-whirlwind-fighter-of-world-war-ii/

 

Well worth the time to read - I didn't realise that the Whirlwind was the first to try leading edge radiator intakes despite having looked at the plane so many times. The penny never dropped. Another interesting titbit is that Dowding held the Whirlwinds back in Scotland not because they were failures, but to save them for low level attacks on German landings, which makes sense. In 1940 nothing would have been able to stop them causing havoc. (The Whirlwinds or the Germans? )

 

Imagine a world where Sealion was attempted and Britain was saved not by the Spitfire (allegedly) but by the Whirlwind, and there is one in the BoB flight screaming around airshows to this day, powered by the rage of the ground crew that have to work on it.

[EwenS]

This revelation first came out a few years back in an article in The Aviation Historian, which you can find now on the Whirlwind Project site Blog page

https://www.whirlwindfp.org/blog/when-the-wind-won-t-whirl-or-the-real-reason-the-whirlwind-suffered-at-height

 

 

 

[wellsprop]

5 hours ago, Folkbox1 said:

 Admittedly, merlins would probably have had enough power to compensate. 

 

I'm afraid this is where it gets extremely complicated. Everything with aerodynamics is more complicated than you think.

 

The blades were completely wrong, adding power wouldn't fix (or overcome) the aerodynamics.

 

The blade thickness meant the blades encountered compressibility problems, as soon as an aerofoil meets compressibility, it fundamentally stops doing it's job. The blades weren't able to do anything with the power, having more power wouldn't help.

 

This is the same reason late war piston aircraft started to encounter loss of control at high speeds, adding extra speed makes the problem worse, not better. 

 

As an aside, I really enjoy the We Have Ways podcast, but Al and James are not engineers and it's very evident in the way in which they explained some of the issues with the Whirlwind. I messaged them on Twitter about it and they are both very open to corrections/learning about these engineering principles. 

[Eric Mc]

Yes, I have read and seen (on You Tube)  that the propellers really were the main problem with the Whirlwind rather than the Peregrine per se. Like the Typhoon later, which also floundered at altitude, the Whirlwind found itself a very effective niche in the ground attack role where the compressability issues were not relevant.

 

However, the Peregrine itself was a problem too in that the Air Ministry told Rolls Royce not to spend any more time and effort on a number of their engine projects - which included the Peregrine and, even more infamously, the Vulture. Because of the pressures of wartime production, Rolls Royce had to concentrate on the Merlin and Griffon.

 

There had also been misgivings about Westland's ability to mass produce complicated and advanced aircraft like the Whirlwind so, in many ways, the Whirlwind battled to enter production at all. It was always fighting an uphill battle.

[Graham Boak]

A couple of points here. 

 

I don't think that it was as much the Air Ministry telling RR as RR telling the Air Ministry that they just couldn't cope with the number of projects they had to handle.  The Barracuda's Exe was another significant victim.  However these things do tend to be joint decisions.  The Vulture was another engine believed to have suffered from this compressibility problem on the DH prop.

 

The propeller problem meant that the production Whirlwind did not match that of the prototype at altitude, in this case around 20,000ft.  But by the time the Whirlwind actually reached the squadrons the Air Ministry were already looking for even higher altitudes, with the two geared Merlin.  By then the Mosquito would be available in the same timescale, and a four cannon fighter was available in the Hurricane Mk.IIC.

[Bozothenutter]

I'm still amazed at how long various countries wanted to maintain twin engined 'fighters', since the whole concept wasn't that successful (a certain wooden wonder excepted....)

[Graham Boak]

Depends what you mean by "not that successful".  Night fighters were predominately twin engined because of endurance and load carrying.  Anti-shipping work was mainly the realm of twin-engined fighters, as was (until 1944)  long range operations.  The Beaufighter was successful.  After stopping thinking of it as a dogfighter, as was the Bf.110.  And the Lightning.  What about the Ju.88?  

[TallBlondJohn]

Twin engined fighters... EE Lightning, F4, F15, F18, Mig-29, Su-27, Typhoon... they seem to have worked out alright.
 

OK, I know, piston engines. As Graham says once people stopped trying to dogfight twins they became very useful, mostly in the nightfighter or attack role but able to slash and dash, especially the single seaters.

 

My personal theroy-ette is that a lot of the 1930s heavy fighter enthusiasm looked back to WW1 and in particular the Bristol Fighter. Definitely a fighter but it could dogfight and its size, 2 seats and carrying ability made it very useful in other roles - it stayed in service until 1932. So a modern equivalent seemed a great idea - but a rear gunner with one gun, requiring respect in a 1918 dogfight, won't cut it in 1940.

[Graham Boak]

It is usually the Defiant that the Brisfit is credited with inspiring.   I rather doubt both suggestions, as both the turret fighter and all the twin-engined fighters had their own reasons for coming into existence.  If you really want a  predecessor from WW1 the Caudron R.11 might be better, it being considered a highly effective escort fighter.

[Bozothenutter]

15 hours ago, Graham Boak said:

Depends what you mean by "not that successful".  Night fighters were predominately twin engined because of endurance and load carrying.  Anti-shipping work was mainly the realm of twin-engined fighters, as was (until 1944)  long range operations.  The Beaufighter was successful.  After stopping thinking of it as a dogfighter, as was the Bf.110.  And the Lightning.  What about the Ju.88?  

that's what I meant, they were unsuccessful as fighter fighters, but turned into very good ground attack/night fighters (bombers)

[Graham Boak]

There's still their use as long range fighters, as examples over the Bay of Biscay and in the Mediterranean.  They were generally found lacking as short-range interceptors, and as dogfighters - although there were a number of examples on aces in Bf.110s, and the P-38 is the star exception.  Perhaps, had the Whirlwind been available in time for the one battle it might have made a difference, it could have joined the select band.

[Giorgio N]

22 hours ago, Bozothenutter said:

I'm still amazed at how long various countries wanted to maintain twin engined 'fighters', since the whole concept wasn't that successful (a certain wooden wonder excepted....)

 

The Mosquito is no exception if you look at the use of twin engined types as "fighters": it was a great aircraft but was not meant to be used against single-engined types and its career was really that of a night fighter or ground attack aircraft. From this point of view the Ju-88 was equally successful.

The only exception from this point of view was the P-38, that at least in the Pacific was very successful also against single-engined fighters (less so in Europe). The Lightning however was designed to a different concept, yes had two engines but only one crew member and was generally lighter than other twin-engined types (Whirlwind excepted)

[Dave Swindell]

The Mosquito was initially designed as a bomber and only later adapted to the fighter role, and only then as a night fighter where a 2nd crew member was required to operate the radar equipment, or as a fighter bomber.

De Havilland's answer to the Whirlwind would be the Hornet, designed from the outset as a single pilot twin engined fighter - too late for service during ww2 but it served with the RAF and FAA for nearly 10 years immediately afterwards.

[Eric Mc]

And what about the Welkin? That showed that Petter's concept was sound - but rather unnecessary by the time it arrived on the scene.

 

I was reading a book on the Whirlwind not that long ago and what did emerge from the book was the lack of confidence the Air Ministry had in Westland's ability to mass produce. At the time the Whirlwind was entering production, Westland were already struggling to meet their Lysander targets.

 

Also, Supermarine were also showing that some of these small, southern based, manufacturers lacked big enough factories and a large enough skilled workforce to mass produce on the scale required.  The Spitfire was saved by the decision to concentrate production at the new Government built factory at Castle Bromwich - although that took a lot of sorting out. It is likely that something similar would have been needed to build the Whirlwind in large numbers. 

Edited October 26, 2023 by Eric Mc

[Graham Boak]

The Welkin unfortunately did little that the P-38 couldn't.  Or the Mosquito Mk.XV.  It certainly wasn't an attempt to do with two smaller engines what a fighter with more powerful ones could.  It may have shown that the overall configuration was ok - but that was hardly revolutionary.

 

What the Whirlwind demonstrated, sadly, was that lightweight solutions are not as useful as larger ones, and require going to extreme lengths to be compact and save weight. The Whirlwind was a small twin with a heavy armament - not something that could be said about the Welkin..

 

 

I

[Eric Mc]

17 hours ago, Graham Boak said:

The Welkin unfortunately did little that the P-38 couldn't.  Or the Mosquito Mk.XV.  It certainly wasn't an attempt to do with two smaller engines what a fighter with more powerful ones could.  It may have shown that the overall configuration was ok - but that was hardly revolutionary.

 

What the Whirlwind demonstrated, sadly, was that lightweight solutions are not as useful as larger ones, and require going to extreme lengths to be compact and save weight. The Whirlwind was a small twin with a heavy armament - not something that could be said about the Welkin..

 

 

I

I never said the Welkin was revolutionary. In fact, by the time it flew, it wasn't , and, more importantly,  it was not needed. But it showed that Petter's original concept was OK. It was just that it wasn't realised in the Whirlwind and by the time the Welkin had arrived, it was not required.

 

The Whirlwind was a small twin because it had small engines - the Peregrine.. Which, as we have discussed, Rolls Royce discontinued. When a bigger engine (the Merlin) was used, the airframe necessarily had to be bigger to accommodate it. But by then, we had other aircraft that could do the same job and the jets were coming along - so it was not pursued.

 

As for the P-38, the RAF never really wanted it so not really relevant to this particular discussion. The RAF's short experience with the P-38 was less than satisfactory although that was as much to do with the fact that the version they were given didn't have all the attributes of the USAAF versions.

Edited October 27, 2023 by Eric Mc

[EwenS]

14 minutes ago, Eric Mc said:

I never said the Welkin was revolutionary. In fact, by the time it flew, it wasn't , and, more importantly,  it was not needed. But it showed that Petter's original concept was OK. It was just that it wasn't realised in the Whirlwind and by the time the Welkin had arrived, it was not required.

 

The Whirlwind was a small twin because it had small engines - the Peregrine.. Which, as we have discussed, Rolls Royce discontinued. When a bigger engine (the Merlin) was used, the airframe necessarily had to be bigger to accommodate it. But by then, we had other aircraft that could do the same job and the jets were coming along - so it was not pursued.

 

As for the P-38, the RAF never really wanted it so not really relevant to this particular discussion. The RAF's short experience with the P-38 was less than satisfactory although that was as much to do with the fact that the version they were given didn't have all the attributes of the USAAF versions.

The RAF decided post BoB and the experience gained then, that the P-38s they had on order courtesy of the French, needed the turbo-supercharged engines. Renegotiating the contract took until Aug 1941 with the first 143 to be built with non-turbo engines and the rest with turbo engines. Then the stories about its high speed handling with the prototypes came out in late summer 1941 at which point the RAF wanted to cancel the whole order but Lockheed wouldn’t let them. Then Pearl Harbor and the USAAF decided it needed every fighter it could get so took over everything - aircraft in build and to be built. The RAF only received 3 non turbo aircraft in March 1942 for trials.

[Eric Mc]

8 minutes ago, EwenS said:

The RAF decided post BoB and the experience gained then, that the P-38s they had on order courtesy of the French, needed the turbo-supercharged engines. Renegotiating the contract took until Aug 1941 with the first 143 to be built with non-turbo engines and the rest with turbo engines. Then the stories about its high speed handling with the prototypes came out in late summer 1941 at which point the RAF wanted to cancel the whole order but Lockheed wouldn’t let them. Then Pearl Harbor and the USAAF decided it needed every fighter it could get so took over everything - aircraft in build and to be built. The RAF only received 3 non turbo aircraft in March 1942 for trials.

Indeed. Not a great experience for the RAF.

[Graham Boak]

Just what do you mean by "concept"?  The design configuration isn't, particularly, except in being a twin-engined single seater with heavy armament.  Much of the ingenuity went into more detailed design coping with insufficient power and achieving a low weight.  The end result was certainly interesting but of limited value.  A good comparison might be the Fw.187, except that the RLM had the sense to cancel that.

 

The P-38 with turbochargers could achieve the speed and altitudes of the Welkin.  Its later availability meant that the RAF didn't need the Welkin, and the time and effort could have been spent more profitably.  "By the time it came along" ignores the facts that it didn't rise fully formed from the West Country, but was factored into force projections for several years before that.  As were the "other aircraft that could do the same job".  Using the design as a means of maintaining a design team may have had value, building so many was folly.

 

Yes, it is much easier to judge these things later.  The appearance of the Ju.86P/R must have mislead the planners to the capability of the German industry to follow up with a force of bombers.

[Eric Mc]

I'm not into arguing on the internet - it's a waste of time and effort to no purpose.

 

So I will make no further comments on this topic save to say I have always liked the Whirlwind - an aeroplane that could have been great but which fell just short. 

 

 

[Folkbox1]

Thanks guys.  Interesting subject and one of my favourite planes.  After years of thinking it was the engine it was interesting to hear why it wasn't (aerodynamics isn't my forte but I think i've understood the reasons).  Still baffling that they stuck with that propeller and didn't go for the one used on the prototype - perhaps that was needed more urgently by Spits or Hurris, I don't know.

 

Darren

[Graham Boak]

They simply didn't know.  This explanation has come out of research carried out for the new build currently underway.  The drop in performance will have been considered as due to the known truism that manufacturer-prepared prototypes will outperform the later production examples, so they will have been looking for reasons such as increased weight and lower build standards.

[Welkin]

Just picked up on this thread.

Were the propellers used by the Whirlwind used on any other aircraft?

Westland were able to build a large number of Seafires, albeit later in the war.

[Peter Lloyd]

The engine 'problem' never made sense to me: Whirlwinds flew many, many sorties long after the 'customer support' for the Peregrine ended (which led me to suppose the industrial effort per se, rather than technical issues, caused the cut).

 

As other have said, twin engines fighters were not failures.  Most early WW2 single engined fighters were so short legged that air forces were left with vast areas where a less agile plane could still rule.  The Spitfire is a legend but it was truly notable for all the battles in which it never took part.  Why the RAF was so utterly uninterested in an escort fighter, given it's doctinal obsession with bombing, is a real historial oddity.