Westland Whirlwind revisited

[Admiral Beez]

Though I would have liked to see a Mosquito with 4 Peregrines.

Like an upengined DH Albatross.

 

[Wild_Bill_Kelso]

I assume they could have been available for the BoB by September 1940, had Dowding actually approved 263 Squadron to be used

I figured unsuitable for BoB due to altitude limitation

 

[tomo pauk]

I figured unsuitable for BoB due to altitude limitation

Care to elaborate?

 

[Wild_Bill_Kelso]

Care to elaborate?

My understanding is that the peregrine had a relatively low critical altitude, top speed is given at 15,000 ft on the Wiki, though of course I don't know if that is accurate.

 

[MikeMeech]

Care to elaborate?

Hi
Dowding's 'Battle of Britain Despatch' mentions the aircraft types, including the Whirlwind, Para 97, these are his thoughts on the subject of aircraft types:

Mike

 

[tomo pauk]

My understanding is that the peregrine had a relatively low critical altitude, top speed is given at 15,000 ft on the Wiki, though of course I don't know if that is accurate.

Rated altitude was at 15000 ft. There it was supposed to make 885 HP, RPM being 3000 and boost of +6.75 psi*.
DB 601A have had rated altitude at 4000m, while the later DB 601A (available some time in 1940?) have had the rated altitude of 4500m. That is ~13120 ft and ~14760 ft, respectively; 1020 PS (1006 HP) was the power there.
Allison V-1710-33, from mid-1944, have had rated altitude of 13200 ft, power of 1090 HP (later these figures will be a bit revised).
HS 12Y-45 rated altitude was at 4200m (13780 ft) for 920 CV.
These are the 'better' engines that matter for 1940. HS 12Ys on the MS 406 were hopeless, Fiat A.74 was even worse, the R-1830 was no great shakes either, and Soviet best engines are meh in 1940.

* Wikipedia is wrong here wrt. boost: Power output: 885 hp (660 kW) at 3,000 rpm, +9 psi boost
At +9psi, we'd get easy-peasy 1000 HP from a Peregrine (but at perhaps 10000-12000 ft, not at 15000).

tl;dr: rated altitude of the RR Peregrine was just fine for 1940.

 

[Wild_Bill_Kelso]

Well I don't think it was enough power at altitude for an aircraft of that weight. Spitfires and Bf 109s had higher than 25,000' ceiling and were still performing pretty well at that altitude. Because of the nature of the BoB a lot of the fighting was done at that altitude. None of the American fighters available at that time, like the P-36, were considered suitable for the BoB. Nor would the P-40 have been if it was available.

I do, however, think Whirlwind was a useful aircraft which could have been helpful in many Theaters, including flying from England as it in fact did, in the role or protecting the channel.

 

[MIflyer]

I don't think that the Whirlwind had featherable props, either, nor did any British made aircraft of that era other than the Manchester.

Even at that the Whirlwind pilots were more willing to fly home from France with one turnin' and one burnin' than were the Typhoon pilots with a misbehaving engine. I'd guess that the ditching characteristics of the Whirlwind were better than the Typhoon; they hardly could have been any worse.

More evidence that even in 1941 it was quite hard for a twin to top a P-38.

 

[Wild_Bill_Kelso]

12Y may have been "hopeless" but on the <6,000 lb D.520 it was able to confer a 10,000 meter ceiling

 

[Wild_Bill_Kelso]

I don't think that the Whirlwind had featherable props, either, nor did any British made aircraft of that era other than the Manchester.

Even at that the Whirlwind pilots were more willing to fly home from France with one turnin' and one burnin' than were the Typhoon pilots with a misbehaving engine. I'd guess that the ditching characteristics of the Whirlwind were better than the Typhoon; they hardly could have been any worse.

More evidence that even in 1941 it was quite hard for a twin to top a P-38.

Gloster F9 looks pretty good at that time period too, I'd say... Mosquito was flying in 1941though in very small numbers. Beaufighter was available too. Neither had precisely the same strengths as the P-38 but I'd say both were at least as useful overall. And I don't think a 1941 vintage P-38 was of much benefit to the war effort yet.

 

[tomo pauk]

Well I don't think it was enough power at altitude for an aircraft of that weight. Spitfires and Bf 109s had higher than 25,000' ceiling and were still performing pretty well at that altitude. Because of the nature of the BoB a lot of the fighting was done at that altitude.

I've read on the internet that Whirlwind have had two engines, meaning that available power at 15000 ft was 1770 HP. Even the He 113 was worse there.
How much the high wing loading was to blame the Whirly dishing it out at 25000 ft?
What was the percentage of LW bomber sorties flown at 25000 ft?

12Y may have been "hopeless" but on the <6,000 lb D.520 it was able to confer a 10,000 meter ceiling

Where have I stated that D.520 have had a hopeless engine?

 

[warbird51]

I figured unsuitable for BoB due to altitude limitation

Didn't the Whirlwind have same altitude limitations that the Spitfire Mk 1 had ?

 

[MiTasol]

And don't forget that the one prototype with the Dowty props was not altitude limited in the way the DH prop aircraft were.

 

[GrauGeist]

None of the American fighters available at that time, like the P-36, were considered suitable for the BoB.

In 1940, the P-36 was still a serious adversary - the French Curtiss 75C-1 accounted for a majority of victories over the Luftwaffe.

 

[don4331]

Rated altitude was at 15000 ft. There it was supposed to make 885 HP, RPM being 3000 and boost of +6.75 psi*.

* Wikipedia is wrong here wrt. boost: Power output: 885 hp (660 kW) at 3,000 rpm, +9 psi boost
At +9psi, we'd get easy-peasy 1000 HP from a Peregrine (but at perhaps 10000-12000 ft, not at 15000).

tl;dr: rated altitude of the RR Peregrine was just fine for 1940.

You are assuming the intake system (supercharger, carb, ducting, valves, etc) on the Peregrine has capacity to increase boost at more less same efficiency. However, if limitations in system e.g. max airflow through carb has been reached, preventing additional airflow, the increased boost might simply be heating mixture. From what I see in charts, Peregrine gained ~80hp from 5 psi (max cruise) to 6.75psi (max power); Given you're only increasing 2.25 psi, getting 1k hp isn't exactly easy-peasy. Definitely worthy of betting a pint over.

Didn't the Whirlwind have same altitude limitations that the Spitfire Mk 1 had ?

Lower wing loading/better airfoil of Spitfire means it does have same altitude limitations as Whirlwind. Spitfire Mk.1 has ~34.5k' service ceiling (with Rotol CS prop)

And don't forget that the one prototype with the Dowty props was not altitude limited in the way the DH prop aircraft were.

The extra 5k' (30.3k' vs 25k' service ceiling) for Rotol over DH is less altitude limited, but still not in Spitfire league.

 

[Wild_Bill_Kelso]

In 1940, the P-36 was still a serious adversary - the French Curtiss 75C-1 accounted for a majority of victories over the Luftwaffe.

The P-36 / Hawk 75 was indeed a serious adversary, but in France it did most of it's fighting over the battlefield where most of the bombers were flying low. Same for Finland. There is a big difference between a close air support role and the fighter cover for that, vs. strategic (and terror) bombing of the type going on in the BoB. Russian fighters also had fairly poor high altitude performance but they didn't need it.

Over England though, the fighters needed to be able to fly high.

Different Theaters, different environments, different requirements.

 

[Wild_Bill_Kelso]

I've read on the internet that Whirlwind have had two engines, meaning that available power at 15000 ft was 1770 HP. Even the He 113 was worse there.

Yes but the He 112 didn't weigh 10,000 lbs

How much the high wing loading was to blame the Whirly dishing it out at 25000 ft?
What was the percentage of LW bomber sorties flown at 25000 ft?

I'm hardly an expert on the BoB, as it's not a major area of interest for me, but I think if your ceiling is 25,000 ft, you are probably not that peppy at 20,000. And I believe German bombers were flying at fairly high altitude (above 20,000') for a lot of their raids. The bomber doesn't need so much power to just fly over the target and stay in formation, while the fighter does.

Where have I stated that D.520 have had a hopeless engine?

You said "HS 12Ys on the MS 406 were hopeless" (although it managed a ceiling of 9,400m according to the Wiki. The D.520 also used a 12Y, albeit a slightly newer variant.

 

[Shortround6]

The trouble with the BoB as a benchmark was that you needed hundreds of fighters to make a big difference.
Getting one squadron into service in Sept (or July or November ) wasn't going to make any difference to the battle as a whole.

They only had a few squadrons of Defiants as day fighters. They boosted the German scores as much as they hurt the Germans.
Every 2nd rate squadron allowed a 1st rate squadron to moved closer to the main battle area instead of guarding the fringes but not even a single squadron of time traveling Spit IXs was going turn the whole battle around.

I like the Whirlwind and with the aid of hindsight, think it got raw deal.
A lot a not very good math, and some less than realistic expectations about it's competitors.
The whole using two engines when one engine would do the job.
4 cannon Hurricane wouldn't do the job (interceptor or air superiority) when if finally showed up, very late.
4 Cannon Spitfire V ?
4 Cannon Typhoon ? See comments about amount of Aluminum alloy in the Whirlwind or the 2 engines vs 1 engine argument. And with the Sabre we have no idea of what the cost per hp was.

What was being promised in 1940 (or late 1939) was not what was delivered in 1941 and the Germans had not sat on their thumbs and made no improvements to the 109.

Then we get into Service ceiling argument.
My understanding is that the peregrine had a relatively low critical altitude, top speed is given at 15,000 ft on the Wiki, though of course I don't know if that is accurate.

Most planes did not go max speed at the critical altitude. They often did max speed somewhat higher as the critical altitude of the engine does not include RAM. However in the late 30s specifications were often given at fixed intervals, like ever 5,000ft or every 1,000 meters and if a particular plane/engine hit max speed at 17,500ft, too bad, it was listed as either speed at 15,000ft or speed at 20,000ft for some British planes. Some European planes were listed at speed an an altitude of 1000 meters times X.
Hurricanes and Spitfires had different critical altitudes as airplanes even though the engines had the same critical altitude. The Faster Spitfire generated more RAM.

Now installation in an aircraft should not affect the critical altitude of the engine itself and but can really affect the critical altitude of the airplane.

I really like the hat

Early Hurricanes and Spitfires (prototypes) had no exhaust thrust. Changing the exhaust pipes improved the speed and climb of the aircraft, especially at altitude but the power to the prop was the same and the critical altitude of the engine stayed the same. Carb inlet could make a difference.
Prop could make a difference in performance but the engine critical altitude stayed the same.

engine builder told the airframe maker what the engine would do without RAM or exhaust thrust and left the airframe maker to sort out the intakes and exhausts and the propellers.
Perhaps not the best way of doing things and RR was doing a lot work helping airframe makers sort out installation even the late 30s and did more as time went on.

Service ceiling is just a comparative number and planes almost never operated at the actual "service ceiling" or even within a few thousand feet of it. It is the altitude at which the plane can still climb 100fpm at climbing power. Some planes take 7-8 minutes to climb the last 2,000ft so it is not really usable.
Operational ceiling is seldom quoted but that was the ceiling at which the plane/s could climb at 500fpm and was considered the altitude at which a formation of planes could maintain formation. A small formation, not 8th Air Force formations.

Service ceiling was the result of not only the altitude capability of the engine but of the aircraft design. Wing loading had a lot to do with it. High wing load aircraft had lower ceilings than low wing load aircraft (bombers often lost thousands of feet of altitude when heavily loaded even though the engines stayed the same). And wing design stated to play a part.
High aspect ratio wings were more efficient than low aspect wings and when your engine is gasping for air and struggling to stay running you need all the wing efficiency you can get
Don't confuse cause and effect.

The Hawker Henley in the photo was supposed to have service ceiling of 27,000ft while using the same engine (and better prop) than the Hurricane.

 

[GrauGeist]

The P-36 / Hawk 75 was indeed a serious adversary, but in France it did most of it's fighting over the battlefield where most of the bombers were flying low. Same for Finland. There is a big difference between a close air support role and the fighter cover for that, vs. strategic (and terror) bombing of the type going on in the BoB. Russian fighters also had fairly poor high altitude performance but they didn't need it.

Over England though, the fighters needed to be able to fly high.

Different Theaters, different environments, different requirements.

The P-36 had a ceiling of 32,000+ feet - not sure how much higher one would need to go, considering BoB's average combat height was 15,000 feet.

Of the battle of France, the Hawk 75 countered fighters as well as bombers in all situations, accounting for about a third of all victories against the Luftwaffe while only losing 29 out of a total of 316.

That's not a bad legacy, at all.

 

[Wild_Bill_Kelso]

The P-36 was a great fighter. It did well in the Battle of France (though not only due to the merits of the aircraft). At 12,000 ft it was a match for a Bf 109E. At 25,000 ft I don't think it was.