Westland Whirlwind revisited

[GrauGeist]

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.

Why not?

It had the P&W R-1830 engine (except for the 81 75A-4s France received, which had the Wright R-1820).

Considering the P-36's service ceiling was over 32,000 feet, where performance is maxed, operating at 25,000 feet would not have been a handicap,

As mentioned earlier, the average altitude was 15,000 feet (altitudes of ten to twenty thousand being the majority of operations).

Many types could go higher, like the Hurricane's max. ceiling of 36,000 feet, but how much combat did the Hurri see at 36,000 feet?

 

[Wild_Bill_Kelso]

Well, feel free to break down the numbers. How much HP was a Hawk 75 producing at 20,000'. At 25,000'. How fast was it at those altitudes.

Here are some tests on ww2aircraftperformance:

P-36A (with R-1830-17) showing 850 hp at 15k ft, 695 hp at 20k ft, for 285 mph, 535 hp at 25k ft for 280 mph. Top speed is 295.5 at 10,000 ft. Climbing 880 fpm at 25,000ft.
P-36A (with R-1830-17) showing 845 hp at 15k ft, 700 hp at 20k ft, for 286 mph, 555 hp at 25k ft for 276 mph. Top speed is 292 at 15,000 ft.

Handbook for Hawk 75-A says top speed 303 mph at 19,000 ft (listed as critical altitude) with GR-1820-105A. That is with one .30 and one .50 machine gun in the cowling.

That's all I could find, do you have stats for Hawk 75A3 and A4?

Compare that to Bf 109E, Bf 110, Spitfire I, and Hurricane I.

Hurricane Mk 1 showing 1,100 hp at 25,000 and 301.5 mph, top speed 314 at 15,000 ft.
Hurricane Mk 1 Data sheet shows 316 mph at 17,750 ft, and 1030 hp at 16,250

That's almost 200 more horsepower at that altitude than the P-36A was making.

Spitfire is doing 353 mph at 20,000 ft and can still climb at 1,840 fpm

My understanding is that the British evaluated the Hawk 75, they liked it (and used it much later in India) but they did not deem it suitable for defense of the Home Island.

 

[tomo pauk]

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.

I'd settle for 20-30 HP less than 1000.

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

Where I've mentioned the He 112 in the post #891?

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.

In other words, you don't know the percentage of LW bomber sorties flown at 25000 ft.

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.

Yes, compared to the premiere engines of 1940, the HS 12Y as used on MS406 were hopeless.
The HS 12Y as used on D.520 were the newer variant.

 

[MIflyer]

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

Yes, I posted an article a while back that said the real problem with the Whirlwind was the props. Don't know if I can find that again.

 

[Admiral Beez]

Yes, I posted an article a while back that said the real problem with the Whirlwind was the props. Don't know if I can find that again.

 

[EwenS]

I think this was what you are referring to

The Westland Whirlwind British fighter aircraft of WW2

dingeraviation.net

And specifically about the prop problem

When the Wind Won't Whirl - or the real reason the Whirlwind suffered at height. - WFP

The Whirlwind was said to have been let down by its engines. This never added up to the WFP's Matt Bearman and in an article originally published in The Aviation Historian quarterly Matt unearths some surprising facts,

www.whirlwindfp.org

 

[MIflyer]

As far as the aircraft specifications, here are the pages from the Green "Fighters" book. Not too detailed, but handy.

You know, the Grumman XF5F would make an interesting comparison.

 

[Shortround6]

Yes, compared to the premiere engines of 1940, the HS 12Y as used on MS406 were hopeless.
The HS 12Y as used on D.520 were the newer variant.

And the newer variant was still hopeless.

It would make 910hp at 5250 meters (17,250ft) which would have been good in 1939, In 1940 not so much. This was due to the S-P supercharger recently discussed which allowed the engine to make the same power from sea level to 5250 meters. Unfortunately that meant it never gave more than 910hp at any altitude. This was in the spring of 1940, Merlin IIIs were being rated for 12lbs boost at low altitude and the Merlin XII was about to be introduced in the Spitfire II in June of 1940.
This is for the -49 engine.
The -50/51 was supposed to be better but it was prototype only and it was maxing out at 1100hp at sea level and 1000hp at 3260 meters (10,670ft) while turning 100rpm faster than the old engines. This was the engine that the Swiss licensed but with the HS supercharger, it took the Swiss quite a while to get the engine to do what they wanted.

 

[yulzari]

The Whirlwind was not without weaknesses but it was the first (and only) production batch. Had it gone into shadow factory production, as it might have at one point, those would have been addressed as would increasing boost on the Peregrine. Even the Bristol Taurus, of little more weight and volume than the Peregrine, could knock out an easy 1,000bhp in reliable form on 87 octane petrol and saw service with up to 1,200bhp so it would be surprising if a tweaked Peregrine could not get into that region. Two stage supercharging might be a tricky fit with the main wheels tucking so close up to the engine but I am not qualified to comment. Maybe a 1944 MkIII whilst 1941 as a MkII with the simplest tweaks.

 

[Geoffrey Sinclair]

Rolls Royce Heritage Trust, 296 Peregrine built February 1940 to January 1942. Rolls Royce apparently made the claim the RAF could have 1 Peregrine or 2 Merlin. Ministry of Aircraft production, 114 Whirlwind built June 1940 to January 1942.

AIR 16/326

Squadron leader Munro, Whirlwind report after 7 months service use. Gentleman's airplane, pilots with no twin engine experience and around 10 hours on Hurricanes are going solo without any preliminary dual training, no accidents. Take off good, climb exceptional to 10,000 feet, very good to 20,000 feet, to 30,000 feet 3 to 4 minutes slower than a Hurricane I. Faster than the Spitfire below 10,000 feet about the same 10 to 20,000 feet, faster than a Hurricane at 30,000 feet. Dives almost too well, better manoeuvrability at 360 mph IAS than the Hurricane and Spitfire, use energy tactics to fight. Aerobatics good and easy to perform, slots help manoeuvrability but their drag above 20,000 feet is a problem. Undercarriage excellent. Single engine flying exceptionally good. Cockpit roomy, well laid out, efficient heating and cooling, view forward very good, to rear hindered by armour plate, so being slightly better than a Hurricane or Spitfire. Very steady gun platform, viewable area helps deflection shooting. Normal serviceability is high but dragged down by inexperienced pilot's accidents and bad patches in airfields. Engines very smooth and start well but do not give their rated boost at altitude. Confident a Whirlwind could be landed at 45 pounds per square foot loading.

Single seat day and night fighter. 31 July 1940, L6845 at 10,072 pounds (tare 8,005, light weight 7,613, fixed military load 393, service load 956 pounds, 1,020 pounds of fuel at 7.7 pounds per gallon, 90 pounds of oil). Engine ratings 860 BHP at rated altitude of 13,500 feet at 2,850 RMP at 6.75 pounds per square inch boost. Rate of climb 2,715 feet/min 2,000 feet (reached in 0.8 minutes) to 10,000 feet (3.7 minutes), 2,310 feet/min at 15,000 feet (5.7 minutes), 1,585 feet/min at 20,000 feet (8.2 minutes), 860 feet/min at 25,000 feet (12.4 minutes), 145 feet/min at 30,000 feet (24.6 minutes), service ceiling estimated 30,300 feet. Take off run 375 yards, to clear 50 foot obstacle 710 yards. Speed 351 mph at 15,000 feet, 354 mph at 15,800 feet (Full throttle height for +6.75 pounds boost), 342 mph at 20,000 feet. Under test conditions, 4.3 mph wind, temperature 19 degrees C, barometer 29.81 inches Hg, take off run 365 yards, to clear 50 food obstacle 660 yards, landing run 635 yards. Mainplanes area 250 square feet gross, 231 square feet nett, loading at 10,700 pounds 40 pounds/square foot gross, 43.5 nett. Wing constructed in 3 sections, fabric covered control surfaces.

Another weight diagram says 136 gallons of fuel at 7.5 pounds per gallon = 1,020 plus 10 gallons of oil at 9 pounds per gallon. Weights, crew plus parachute 200 pounds, Gun load fixed 74 pounds, service load 650 pounds, pyrotechnic load 6.5 pounds fixed, 36 pounds service, electrical load fixed 192 pounds, instrument load 80.5 pounds fixed, 15 pounds service, wireless load 8.5 pounds fixed, 52.5 pounds service, miscellaneous 31 pounds fixed, 3 pounds service, all up 392.5 pounds fixed military load, 956.5 pounds service load.

February 1940, The fuel tanks form the wing skin, special long range tanks reported available to allow around 1,400 miles range at 200 mph.

1 July 1940, Dowding to Beaverbrook, only have 3 Whirlwinds, pilots like them (but they came from Blenheims), given the problems with Lysanders expect plenty of problems, 2 engines to lift 4 cannons is excessive when the new Hawker fighter will lift 6 with 1 engine, may be glad to have them as anti tank and bomber destroyers but glad to drop them when the new Hawker fighter enters production. Note these are first impressions only, do not quote them against me.

24 September 1940, defect report, Carburettors, Slat sprockets, wing tips, fuselage nose portion, hydraulics, engines. The engines giving little trouble, defects with exactor throttle and mixture controls, boost pressure variations under investigation. Engine failure in air due to Bostick cement in fuel filter, the company using the compound to internally seal the fuel tanks. Westland not moving quick enough to fix problems.

25 September 1940, impossible to properly maintain instrument panel through the loading door, a larger trap door to be provided on the 19th aircraft and retrospective action taken. Flap and undercarriage controls to move to new Air Ministry standard. Extractor controls seem good, boost problems are due to the mechanism in the engine. Faulty fuel tanks leaking. Wing tips failing, bad workmanship. Slat modifications. Carburettor intake too long and complicated, a less complicated design would cost 5 mph. Eleventh and later aircraft to have one piece cockpit coupes. Fuselage nose piece strengthened, majority of hydraulic problems due to badly fitted pipes, flexible pipes being experimented with. Currently ignition timing requires removal of propeller, trap door to be fitted for access to engine timing plug. Spare parts are a problem.

17 October 1940, Dowding to Beaverbrook, the "I know Westlands and I know the packet of trouble the [263] squadron would be in for" letter. Dowding states he did not know Peregrine production was coming to an end, he last heard 200 Whirlwinds at 2 per week on order.

27 November 1940, Sholto Douglas To Petter 263 squadron to Exeter to have Whirlwinds, but Westland seems to be concentrating on building irrelevant Lysanders instead of much wanted Whirlwinds.

Quentin Brand to Sholto Douglas, 3 March 1941, Whirlwind, unsatisfactory manoeuvrability, linked flap and radiator controls a problem for go arounds, cockpit must be closed during flight, 200 hours to change the mainplane outboard of the engine, and 3 to 4 days to change an engine. Prefer no extension of Whirlwind use.

14 March 1941 Sholto Douglas to Under Secretary of State, indifferent performance about 20,000 feet, poor manoeuvrability, closed cockpit in flight, rear view no better than the Spitfire and Hurricane, linked flap and radiator controls a problem for go arounds, 200 hours to change the mainplane outboard of the engine, and 3 to 4 days to change an engine. Prefer no extension of Whirlwind use, one or two squadrons employed outside enemy fighter range is enough.

Undated Whirlwind II proposal, 60 more gallons of fuel (all in tank mid way between cockpit and tail?). 31 gallons/15 minutes take off and climb, 19 gallons/25 minutes at 220 mph to target area, 55 gallons/35 minutes patrol and action at an average 310 mph, 19 gallons/25 minutes at 220 mph return, 10 gallons for 15 minutes reserve. Going from 134 to 194 gallons of fuel increases the target area patrol and action to 115 gallons/75 minutes. Other improvements to raise top speed to around 380 mph. In a climb the Whirlwind is faster than a Spitfire until 27,500 feet where the times are equal at about 13.5 minutes but the Spitfire takes about 17 minutes to 30,000 feet the Whirlwind about 24.

AVIA 46/122

First prototype first flown 11 October 1938, second prototype 29 March 1939. Delay due to new design features plus, 3 month delay in engine delivery (February to May 1938), 3 month delay in undercarriage delivery, 3 month delay in oil cooler delivery, numerous small installation difficulties around July 1938, failure of Simmonds controls, replaced by Exactor, failure of a hiduminim casting in August 1938. Brief handling trials report, excellent fighter and exceptionally easy to fly. First prototype had handed engines, not the second, which was fitted with bullet proof windscreen and full armament. Tests showed practically no difference between having handed and non handed engines installed.

The order for 200 was only placed after the prototype had flown but whether handed engines were to be installed remained an issue, Westland pressed strongly on Spring 1940 for handed engines. The delay of the engine decision was a main reason the original promise of 9 months from order to delivery did not happen, becoming around 18 months, the time line for the second prototype has an entry "delivery of engines becomes a matter of urgency". Along with this Westland was trying for few changes, the Air Ministry noting the delays and wanting an up to date version requiring many changes. The compromise was many changes from the 25th aircraft onwards, after the firm was rapped over the knuckles about its estimates on the delays the changes would cause. The firm neglected the need for advanced notification of equipment requirements, not good in the 1940 crisis. The decision to cut Peregrine production was made in "the middle of the Battle of Britain" [Westland was informed on 8 May about this]. "The aircraft was incapable of development because the structure was neither roomy enough nor strong enough to take larger and more powerful engines."

The only development of the Whirlwind was the fighter bomber modification. Requested on 3 July 1942, approved on 9 July, tests done by 9 September. A pair of 500 pound bombs under the wings, a simple modification being done by unit personnel assisted by Westland engineers. On 6 December approval for universal carriers to carry 250 or various 500 pound bombs, 50 sets of parts being made.

Peregrine production schedule was 8 in February 1940, 12 in March, 22 in April rising to 48 in December, actual production was 3, 1 and 10 then 21 in December.

First Whirlwind production order for 200 on 18 January and 200 more on 5 April 1939? First production delivery 15 June 1940, second 13 July, by 20 July a total of 4 deliveries.

RAF Census End February 1943, 33 operational Whirlwind plus 3 others in Fighter Command, 15 in the maintenance system, 2 instructional airframes, 62 lost, 1 foreign power = P6994 to USA, shipped 5 June 1942, total 116 including the 2 prototypes. End June 1944, 18 in maintenance system, 2 instructional airframes, 93 lost, 1 foreign power, total 114 production examples.

 

[Shortround6]

In other words, you don't know the percentage of LW bomber sorties flown at 25000 ft.

Not too many with bomb racks full

Trips home could be higher but then spending time climbing instead of running may not have worked out any better.

A lot of the German bombers were lucky they could make 22-23,000ft with a bombload. They could reach 26-27,000ft with 1/2 fuel and bombs gone and not flying in formation.

The Germans were working hard to improve things but again, a few Ju-88A-4s sprinkled in with the A-1 and A-5 wasn't going change much.
Better DB 601 engines in the last of the He 111Ps wasn't going to change much and the better Jumo 211s for the He 111Hs also took a while to show up.

The race for altitude over England was due to the British, if possible, wanting to dive from above on the bomber formations so they wanted to be several thousand feet higher. The Germans in turn wanted the 109s (and 110s) to bounce the British from even higher up and the British countered by attacking the the escorting fighters from above (even higher) and then either blowing through the German fighters or keeping them busy while another British squadron went for the bombers. This was theory and often things did not go according to plan. The British had radar and the whole command and control thing going on and a lot more warning time than the French had.

The British also were not looking at the Hawk 75 with favor due to the 5.? numver of guns compared to the British 8. They really didn't like the P-40s when the .50s malfunctioned leaving them with 4 guns. The fuselage guns in the Mohawks didn't have the rate of fire the wing guns had so they were the equivalent of more than 1 gun but not the full 2.

The P & W R-1830 engines in the Hawks/P-36s had single speed superchargers that had critical altitudes of around 6,500ft to 7,500ft, kind of depends how hard you were willing to run them.
For take off they were rated at 2700rpm and 1200hp on 100 octane fuel. The US military and P & W never gave them a military rating and the 1050hp rating you see was the max continuous at 2550rpm. There may have been a cooling problem? preventing the engines from being run at 2700rpm for 5 minutes?

 

[Wild_Bill_Kelso]

I'd settle for 20-30 HP less than 1000.



Where I've mentioned the He 112 in the post #891?

You said He 113, which didn't exist. Trying to be cute? I assumed you meant a fighter in the real world.

In other words, you don't know the percentage of LW bomber sorties flown at 25000 ft.

Who would know that without going and looking it up? I said, - and I believe - that there were quite a few in the vicinity of 20,000 ft where I said, and believe, that the Whirlwind wouldn't be performing well enough to contend with Bf 109.

Yes, compared to the premiere engines of 1940, the HS 12Y as used on MS406 were hopeless.
The HS 12Y as used on D.520 were the newer variant.

Well I think that is picking nits, 12Y-31 and 12Y-45 or 49 are not vastly different engines, and the 12Y-45 and 49 were around at the same time as the peregrine so I don't get what your point might have been.

 

[Wild_Bill_Kelso]

And the newer variant was still hopeless.

It would make 910hp at 5250 meters (17,250ft) which would have been good in 1939, In 1940 not so much. This was due to the S-P supercharger recently discussed which allowed the engine to make the same power from sea level to 5250 meters. Unfortunately that meant it never gave more than 910hp at any altitude. This was in the spring of 1940, Merlin IIIs were being rated for 12lbs boost at low altitude and the Merlin XII was about to be introduced in the Spitfire II in June of 1940.
This is for the -49 engine.
The -50/51 was supposed to be better but it was prototype only and it was maxing out at 1100hp at sea level and 1000hp at 3260 meters (10,670ft) while turning 100rpm faster than the old engines. This was the engine that the Swiss licensed but with the HS supercharger, it took the Swiss quite a while to get the engine to do what they wanted.

And yet

1) the D.520 proved to be a viable fighter which did pretty well in engagements with Allied types well into 1943 and
2) there were many other 12Y variants with increased power, despite what you always say against it. The French seemed to be pretty confident in not just the 12Y-50 and 51 but also the 12Y-77 and 12Z which did actually get into small scale production (in Spain) though the Spanish were not able to sort out teething problems.

 

[Shortround6]

Rolls Royce apparently made the claim the RAF could have 1 Peregrine or 2 Merlin.

I went round and round with no deceased member on this issue. RR may have wanted to kill the Peregrine, at this point not used in or likely to be used in anything else. There are a few simple accounting tricks to use doing this type of comparison. Like if you have several production lines/streams making Melrins and you shut one down to change over to make Peregrines, run a small batch of Peregrines (20?) and then change all the machinery back to Merlins and do that several times and charge all the change over (dead production) time to the Peregrines you can get the Peregrines to cost 2 Merlins each in lost production. RR was not lying but perhaps not quite telling the truth.

200 hours to change the mainplane outboard of the engine, and 3 to 4 days to change an engine. Prefer no extension of Whirlwind use.

There were a bunch of exaggerated claims about maintenance of the Whirlwind being put into memo's.

 

[Frog]

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.

Good planes, manned by good pilots, hampered by mitigated tactics and deficient ground control.

 

[Juha3]

On P-36/Hawk 75A
The Finns found out that the Bristol Blenheim was faster than the Hawk 75A above 13000 ft and the Hawks escorting a PR Blenheim flying at 20,000 to 23,000 feet had to fly full throttle to stay with their charge. And at the end of the BoB, the Germans started using Bf 109 fighter-bombers flying at 20,000 feet. Even Spits had difficulties to intercept these, so IMHO pretty impossible to Hawks.

 

[Clayton Magnet]

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. Early Hurricanes and Spitfires (prototypes)

I really like the hat

had no exhaust thrust.

I had no idea that the Hurricane prototype had a retractable tail wheel.
You learn something new everyday

 

[MIflyer]

hey really didn't like the P-40s when the .50s malfunctioned leaving them with 4 guns.

I understand that in North Africa the Tomahawk I's had their nose mounted .50 cal guns replaced with .303. I assume that was due to logistics but perhaps reliability had something to do with it.

 

[Greg Boeser]

On P-36/Hawk 75A
The Finns found out that the Bristol Blenheim was faster than the Hawk 75A above 13000 ft and the Hawks escorting a PR Blenheim flying at 20,000 to 23,000 feet had to fly full throttle to stay with their charge. And at the end of the BoB, the Germans started using Bf 109 fighter-bombers flying at 20,000 feet. Even Spits had difficulties to intercept these, so IMHO pretty impossible to Hawks.

Weren't the Finns using licence built Swedish SC3-Gs?

 

[GrauGeist]

Weren't the Finns using licence built Swedish SC3-Gs?

The Finns got a mixed bag of captured Hawks from Germany, such as Norwegian and French with different sub types.

They did remarkably well against the VVS, too.