Westland Whirlwind alternative engines?

Any change in engine for the Whirlwind would be a huge challenge. It was a very small aircraft and putting a new engine would almost certainly result in unacceptable changes to the structure. Any change is likely to result in a thirstier engine and that would significantly impact the range.

Sort of like pulling the Sabre out of a Typhoon and putting a Merlin on each wing and sticking the guns back in the fuselage

Glider said:

Any change in engine for the Whirlwind would be a huge challenge. It was a very small aircraft and putting a new engine would almost certainly result in unacceptable changes to the structure. Any change is likely to result in a thirstier engine and that would significantly impact the range.

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Re-engining it with Taurus or Persius engines might have been more interesting. The Taurus showed a significant performance boost over the pregrines employed on Gloster's F.9/37 ... Perseus is lighter though. (and had fewerproduction/reliability problems -not sure about altitude performance, I know the Mercury had its share of medium altitude rated variants, but not sure about its sleve-valve successor ... mid-high/high alt performance would still be a problem though given the Merlin developed much more in that direction than Bristol's engines)

Aside from interceptor performance, the radials might have been more interesting for a ground attack/intruder platform. (including freeing up wing space from those radiators, potentially for fuel tankage)

Nacelle shape would still be an issue though, landing gear perhaps less so. (Gloster's design seemed to use a more modular engine installation too, so switching over might not be so straightforward)


There's also the issue of the automatic wing slats. If they'd managed to resolve the problems on those, the low speed handling issues (and landing speed in particular) should have been significantly improved.

The Taurus engines used in the Gloster F.9/37 were a never repeated experimental model. They somehow gave much more power than any service Taurus ever did (same power at a much higher altitude means more power going to the supercharger).

Perseus is lighter but it has the streamlining of a barn door, unless you steal them from Lysander production (or Bothas) they may be in short supply, They pretty much use Hercules cylinders.




Perseus was pretty much abandoned in 1939/40 development wise.

Low speed handling of the Whirlwind wasn't all that bad, one pilots got used to it. Unfortunately, like the P-38, they stuck fighter pilots used to single engine aircraft in the cockpit with only a few hours of twin engine experience (usually on an Anson) and told them to "get on with it". Slats are not magic, they only work at high angles of attack, and slats only affect the area of the wing behind them. They do nothing for the areas of wing that are not behind them. Unless you 3 point land the plane they probably won't do much good. The high landing speed of the Whirlwind was only in comparison with other British fighters of it's time (1939/40). It was quite comparable to the American P-38, P-39 and P-47. All of which were 20-40mph higher than a P-40 depending on actual landing weight.

kool kitty89 said:

Re-engining it with Taurus or Persius engines might have been more interesting. The Taurus showed a significant performance boost over the pregrines employed on Gloster's F.9/37 ... Perseus is lighter though. (and had fewerproduction/reliability problems -not sure about altitude performance, I know the Mercury had its share of medium altitude rated variants, but not sure about its sleve-valve successor ... mid-high/high alt performance would still be a problem though given the Merlin developed much more in that direction than Bristol's engines)

Aside from interceptor performance, the radials might have been more interesting for a ground attack/intruder platform. (including freeing up wing space from those radiators, potentially for fuel tankage)

Nacelle shape would still be an issue though, landing gear perhaps less so. (Gloster's design seemed to use a more modular engine installation too, so switching over might not be so straightforward)


There's also the issue of the automatic wing slats. If they'd managed to resolve the problems on those, the low speed handling issues (and landing speed in particular) should have been significantly improved.

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Good points. I think the problem with a radial is that it would significantly increase the drag, with an inevitable impact on performance. Normally an inlines radiators largely nullify the drag advantage of an inline, but the Whirlwind had cracked this problem.

Low speed handling of the Whirlwind wasn't all that bad, one pilots got used to it. Unfortunately, like the P-38, they stuck fighter pilots used to single engine aircraft in the cockpit with only a few hours of twin engine experience (usually on an Anson) and told them to "get on with it". Slats are not magic, they only work at high angles of attack, and slats only affect the area of the wing behind them. They do nothing for the areas of wing that are not behind them. Unless you 3 point land the plane they probably won't do much good. The high landing speed of the Whirlwind was only in comparison with other British fighters of it's time (1939/40). It was quite comparable to the American P-38, P-39 and P-47. All of which were 20-40mph higher than a P-40 depending on actual landing weight.

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Again good points. The Whirlwind squadrons were given an Oxford so that new pilots could work on their experience with twins as Whirlwinds were too valuable to practice with. However the difference in landing speed between the two must have been pretty scary.

Glider said:

Normally an inlines radiators largely nullify the drag advantage of an inline, but the Whirlwind had cracked this problem.

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The inline vs radial drag advantage bounce all over the place depending on what year you are talking about. Some WW I to 1920s radiator designs were terrible but then the rotary and radial engine installations were pretty bad too. At the end of 20s and beginning of the 30s both camps started to "clean up" their acts. Radials got Townend rings and NACA cowls. Inlines tried steam (Goshhawk for one) and switching to glycol coolant instead of water. The operating temperature of glycol allowed smaller radiators (less drag) to be used. Putting the radiator in a duct and not just hanging it out there or putting it in a box with a somewhat streamline out side was still a few years away. While a NACA cowl was a big improvement for radials there was still a long, long way to go to reach even pre-Fw 190 standards.



The NACA cowl and the wheel pants were good for almost 30mph on the Lockheed Vega but notice there are NO adjustable cowl flaps and internal baffles are pretty sketchy, if there at all.

One camp and then the other would gain the lead for a while (or at least close the gap) but then other camp would develop something new and close it up or swap leads.

duplicate

Shortround6 said:

The high landing speed of the Whirlwind was only in comparison with other British fighters of it's time (1939/40). It was quite comparable to the American P-38, P-39 and P-47. All of which were 20-40mph higher than a P-40 depending on actual landing weight.

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Not quite; the high landing speed was what (according to Dowding in 1940) made it unsuitable as a nightfighter, which closed off another possible use for it.

Shortround6 said:

The Taurus engines used in the Gloster F.9/37 were a never repeated experimental model. They somehow gave much more power than any service Taurus ever did (same power at a much higher altitude means more power going to the supercharger).

Perseus is lighter but it has the streamlining of a barn door, unless you steal them from Lysander production (or Bothas) they may be in short supply, They pretty much use Hercules cylinders.

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From recent discussions (particularly the other Whirlwind and British Radial engine threads) it seemed like the Perseus had similar dimensions to the Mercury, but still a good bit larger in diameter than the Taurus, granted. And I recall the Taurus III's performance being compared to the prototype medium altitude engine on the 9/37 (reduced take-off power, significantly increased FTH) but that it didn't seem to see much/any large scale use in production.

The other Whirlwind thread also got into the issue of Lysander production as a major logistical issue for Westland in general. Shifting priority to a similarly powered Whirlwind has technical merits, and almost certainly an overall more useful aircraft than the Lysander was in service but the political side of things with actual production orders and funding would be the issue there. (that said, such a conversion was never even proposed formally -let alone early enough to sway the powers that be, so it's harder to say if it would have been shot down flat)

Perseus was pretty much abandoned in 1939/40 development wise.

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And given the trouble the Taurus ended up having (and engineering commonality with the Hercules), that's unfortunate, but speculation for a separate thread. (and already came up in one of the recent engine threads)

That said, a medium altitude rated Perseus or Mercury would seem to fit well enough weight wise, likely slower due to drag though. (in the multi-role fighter-bomber and possible anti-shiping role it might have been better suited -and able to take more engine damage ... and stay in production after the Perigrine ceased)
Perhaps a more useful adaptation in the interim had the Merlin adaptation been more seriously considered.


I was also pointing out the low-speed characteristics in terms of the added weight of a possible Merlin adaptation. if they'd managed to address the slat functionality during that redesign, increase in wing size/area might not have been necessary. And while the slats only covered the outer wings, the prop wash at the center sections would have increased lift and critical AoA in those regions to a fair extent (similar to the inner wings on the 109). That and avoiding tip-stall would avoid possible wing-dropping related landing accidents, especially if not using counter-rotating propellers. (elliminating torq tends to improve stall characteristics too -the P-38 fared very well there)

Couple of points.

And given the trouble the Taurus ended up having (and engineering commonality with the Hercules), that's unfortunate, but speculation for a separate thread. (and already came up in one of the recent engine threads)

That said, a medium altitude rated Perseus or Mercury would seem to fit well enough weight wise, likely slower due to drag though. (in the multi-role fighter-bomber and possible anti-shiping role it might have been better suited -and able to take more engine damage ... and stay in production after the Perigrine ceased)

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The British, at least in the beginning of the war, considered engines with full throttle heights of around 13,000ft and up to be fully supercharged or high altitude engines, engines with full throttle heights of 3,500-8,000 were "medium" altitude. I know there is a gap there but they didn't seem to make any engines that fell in that gap.

Taurus got a large part of it's power over the Perseus by turning higher rpm. 3300rpm vs 2600-2750rpm. You aren't going to be able to spin the Perseus much faster. A Perseus developed to equal a 1600hp Hercules is going to have around 1025-1030hp. Unfortunately that comes a little late.

Any extra power will be eaten by the extra drag, at least as far a speed goes. Unfortunately that also affects range. You may be able to fit fuel in where the radiators were but a higher drag airplane will burn more fuel even at cruising speeds.

Again, slats only begin to work when the angle of attack exceeds 12-13 degrees and don't show a lot of benefit until the angle of attack gets into the high teens. You either need a really high nose up attitude or a really steep glide path/approach angle. They can help but are not the miracles some people think they are. A number of designers used them in the 1930s (along with fixed or box slots) but general use declined for while.

Leading edge slats are effective in any situation where separation of the air flow around the leading edge may be a factor. They are effectively a type of boundary layer control device. The passive systems of the Whirlwind and Bf 109 were indeed only effective or activated at higher angles of attack. The principal effect of deployed slats is to increase the angle of attack for the stall by ensuring the continuation of the air flow about the airfoil.
Cheers
Steve

Hmm I wonder if the XF5F's performance is at all comparable to what a radial engined Whirlwind might have managed. Those R-1820s are pretty wide and (if the limited information on that plane is accurate) the XF5F was in a similar weight class, had a larger wing area, and managed an impressive speed way down at sea level. Albeit that was with 1,200 HP engines. (but 100 MPH faster than the F2A-2 using the same engine -I've never seen speed at altitude figures for the F5F, though ... if the SL figures are accurate, it should have been somewhere in the 420 MPH range at ~17,000 ft, though)

Of course, the radial engines suggested wouldn't be in that power output range ... at best you've got some Tauruses managing over 1100 hp down low. (admittedly with some gains due to the small diameter)

Level speed is still only one area to consider. Power to weight ratio, acceleration, rate of climb are all important.


Use of counter-rotating properllers might have had some input on the F5F's performance too. I'm not sure how many options there were for those among British engines.

Projected figures and actual figures for the XF5F show a wide discrepancy. The XF5F had some drag problems that were never resolved during the testing phase, like poorly fitting landing gear doors, that make it hard to say if a fully developed version would have come closer to the numbers. I believe there were also some cooling problems.

Speeds may have been 358mph at 17,300ft and 312mph at sea level.

Climb wasn't setting the world on fire either. 4.2 minutes to 10,000ft and 9.3 minutes to 20,000ft. Granted it Probably was done by the standard US procedure of using Military power for the first 5 minutes of the climb and then throttling back to "normal" (max continuous) for the rest of the climb.

These numbers are for 178 US gallons on board. With 277 gallons speed drops about 1mph but climb takes over a minute longer to 20,000ft and service ceiling drops 1000ft.

Shortround6 said:

Speeds may have been 358mph at 17,300ft and 312mph at sea level.

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Ah, OK, that's much more belivable than the commonly sited figures I've seen. (more so since more modest performance would have made the cancellation less unreasonable too)

The X5F5 was good for 358 mph @ 17300 ft with 900 HP. sheet
That is without guns, ammo, not full tanks.

A few belated comments:

1. I would be quite careful with Rubbra's memoirs as any sort of gospel. After all, he is extremely dismissive towarss direct fuel injection and turbocharging. Both areas in which R-R failed miserably. In the section dealing with the the Merlin's valve gear, he fails to admit that R-R screwed it royally by adopting those fixed cam followers, whose problems were never completely solved. V-1710, DB 600 srs and the Jumo 211/213 all used roller followers.

2. If Dowding dismissed the Whirlwind as a night-fighter for "high landing speed", he was incompetent as landing speed alone is meaningless in determining how easy an airplane is to land.

3. The idea that the Hurricane could do all the Whirly could do is obviously horseradish. The Hurricane is among the most overrated aircraft of WW2. E.g. Russian pilots disliked it s lot and Finnish Buffaloes made mincemeat of opposing Hurricanes. It was considered one of easiest opponents to shoot down.

4. A feasible alternative engine might have been the R-1820. If W-pedia is correct on the Peregrine's weight, the Cyclone did not weigh much more and gave 1200 hp on 100 octane at that time.

About slats: slots could be also quite effective. Finnish VL designed slots for both the Fokker D.XXI and the Pyry trainer and the slots gave a significant improvement in stalling.

Trilisser said:

A few belated comments:

1. I would be quite careful with Rubbra's memoirs as any sort of gospel. After all, he is extremely dismissive towarss direct fuel injection and turbocharging. Both areas in which R-R failed miserably. In the section dealing with the the Merlin's valve gear, he fails to admit that R-R screwed it royally by adopting those fixed cam followers, whose problems were never completely solved. V-1710, DB 600 srs and the Jumo 211/213 all used roller followers.

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Rolls-Royce did not fail with turbochargng.

They determined that it wasn't worth the weight and complexity.

Trilisser said:

3. The idea that the Hurricane could do all the Whirly could do is obviously horseradish. The Hurricane is among the most overrated aircraft of WW2. E.g. Russian pilots disliked it s lot and Finnish Buffaloes made mincemeat of opposing Hurricanes. It was considered one of easiest opponents to shoot down.

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On the other hand, Finland loved the 11 Hurricanes they received

Another resounding spit decision. The Hurricane was either a great plane or else a bad one.

Seems like it depends on who is talking at the time. I bet the BOB pilots would favor it, perhaps not for night fighting, though.