Westland Whirlwind revisited

[SaparotRob]

FWIW I just checked to see if there really was a Rolls Royce Pelican.

 

[wuzak]

Anyway, how was the roll rate for a mosquito?

Not good.

 

[eagledad]

Gentlemen

Attached is a chart which gives rate of roll for selected aircraft with 30 lb stick force, including the Mosquito

Eagledad

 

[don4331]

? I think I have lost track of the discussion.

Some number for comparison.

re the wings, BHP, and weights of the Whirlwind and F5F and P-38

____________________Whirlwind__________XF5F__________ P-38F
Wing Span___________ 45' 0"____________42' 0"___________52' 0"
Wing Airfoil_NACA___ 23015*___________23015* __________23016-4412
Wing Area (gross)______ 250 ft2___________304 ft2__________ 328 ft2
Aspect Ratio__________8.10_____________ 5.80_____________8.24
TOGW (clean)_______10,350 lbs________10,138 lbs**______15,000 lbs
Wing Loading _________41.4 lb/ft2________33.4 lb/ft2* ______ 45.7 lb/ft2
Horse Power_________ 1770 BHP________2000 BHP________2000 BHP (all at 15,000 ft)
Power/Weight ratio___ 0.171 HP/lb______ 0.197 HP/lb______ 0.133 HP/lb
Vmax at 15,000 ft***___~350 mph________~350 mph________~350 mph

*The NACA 23015 is the airfoil for the inner wing section for both the Whirlwind and the XF5F-1. I do not know if the outer wing panels used the same airfoil - they may have been a thinner airfoil. Does anyone have any info on the outer wing panel airfoil sections?

Some observations.

As far as Wing Loading goes, you could increase the TOGW of the Whirlwind by 1,075 lbs and end up with the same Wing Loading as the P-38F. The XF5F-1 is clearly the winner in terms of lower wing loading at 33.4 lb/ft2 for the prototype, and still clearly superior at the projected TOGW of the combat ready F5F-1 airframe at 36.2 lb/ft2.

As far as Power/Weight ratio goes, the XF5-1 is clearly the winner, followed by the Whirlwind, and then the P-38F. The combat ready F5F-1 is still superior - though not as much so - at 0.18 HP/lb.

As far as the Wing T/C ratio goes the Whirlwind and XF5F were the same 15%*, and the P-38 is an average of 14%. The P-38F is slightly superior in the T/C category and this combined with the high Aspect Ratio probably gives it the edge in Cd for the wings.


re a developed Peregrine II engine.

The Peregrin I was slightly more efficient than the Merlin III in terms of HP/in3. If it had been developed further and given the same tweaks as the 'Hookerized ' Merlin, there is (I think) no reason the power could not have been similar to the Merlin 45 in terms of HP/in3 at +9 lbs boost - ie 0.73 BHP/in3. So a 'Hookerized' single-speed Peregrin II should give about 950 BHP at ~15,000 ft.

T ThomasP

From 4+ Publications on Whirlwind, I have the root chord airfoil of 23017 with tip of 23008.
Grumman used 23015 root and 23009 tip in F4F and F6F, the TBF and JRF, so I'd be willing to bet a pint that XF5F had same airfoils. The later Bearcat is 23018 to 23009 and Tigercat is 23015 to 23012.
P-38 has 23016 root airfoil and 4412 tip

I would be careful with "average". Lightning wing is a constant taper, but for both Whirlwind and Skyrocket, it appears only the outer panels taper (both in airfoil section and chord).

Peregrine II is reverse rotation Peregrine I.

I figure Peregrine I was a 975hp engine abeit at lower altitude of 11k' Based on curves presented earlier in this thread/cross referenced versus Merlin II/III which when from 1,030 hp @ 6.25 psi to 1,160 hp @ 9 psi.
I do see opportunity for a "Hookerized" Peregrine III to make 1,300 hp @ 11k'. My concern is how much of the engine is changing?

Does Merlin 45 have larger carb? Do we need to change supercharger step up ratio? Impeller diameter? Did it require thicker gears for increased boost? stronger (larger) bearings? etc. How many jigs, etc in the factory need to be changed for the aforementioned changes. How many of these changes does Peregrine III need?

I can see why Rolls Royce wants to can the Peregrine, every hour of time spent on Peregrine is an hour not spent on the Griffon.

 

[Wild_Bill_Kelso]

FWIW I just checked to see if there really was a Rolls Royce Pelican.

Thank God somebody did

 

[Wild_Bill_Kelso]

Gentlemen

Attached is a chart which gives rate of roll for selected aircraft with 30 lb stick force, including the Mosquito

Eagledad

That! Is! A! Nice! Chart! I hadn't seen before. Too bad it's barely legible. Anybody got a better scan of that?

It's apparently a test of the Boomerang from 1944

Am I reading that right that Tomahawk has the best roll rate at 275? is that Mustang peaking at 350?

 

[Wild_Bill_Kelso]

? I think I have lost track of the discussion.

Some number for comparison.

re the wings, BHP, and weights of the Whirlwind and F5F and P-38

____________________Whirlwind__________XF5F__________ P-38F
Wing Span___________ 45' 0"____________42' 0"___________52' 0"
Wing Airfoil_NACA___ 23015*___________23015* __________23016-4412
Wing Area (gross)______ 250 ft2___________304 ft2__________ 328 ft2
Aspect Ratio__________8.10_____________ 5.80_____________8.24
TOGW (clean)_______10,350 lbs________10,138 lbs**______15,000 lbs
Wing Loading _________41.4 lb/ft2________33.4 lb/ft2* ______ 45.7 lb/ft2
Horse Power_________ 1770 BHP________2000 BHP________2000 BHP (all at 15,000 ft)
Power/Weight ratio___ 0.171 HP/lb______ 0.197 HP/lb______ 0.133 HP/lb
Vmax at 15,000 ft***___~350 mph________~350 mph________~350 mph

*The NACA 23015 is the airfoil for the inner wing section for both the Whirlwind and the XF5F-1. I do not know if the outer wing panels used the same airfoil - they may have been a thinner airfoil. Does anyone have any info on the outer wing panel airfoil sections?

**It was estimated that the TOGW (clean) of a combat ready F5F-1 (ie 4x .50 cal, armour, SSFT, radios, etc) would have been about 11,100 lbs, which would give a wing loading of 36.5 lb/ft2, and a Power/Weight ratio of 0.18 HP/lb.

***The Vmax are for the equivalent of Normal power using 100/130 grade fuel and in temperate conditions. The seemingly slow~350 mph for the P-38F is due to field tests where it was found that the intercoolers and turbosupercharger could not sufficiently cool the charge at higher power settings, causing the V-1710 engines to experience detonation at said higher power settings below about 20,000 ft.

Some observations.

As far as Wing Loading goes, you could increase the TOGW of the Whirlwind by 1,075 lbs and end up with the same Wing Loading as the P-38F. The XF5F-1 is clearly the winner in terms of lower wing loading at 33.4 lb/ft2 for the prototype, and still clearly superior at the projected TOGW of the combat ready F5F-1 airframe at 36.2 lb/ft2.

As far as Power/Weight ratio goes, the XF5-1 is clearly the winner, followed by the Whirlwind, and then the P-38F. The combat ready F5F-1 is still superior - though not as much so - at 0.18 HP/lb.

As far as the Wing T/C ratio goes the Whirlwind and XF5F were the same 15%*, and the P-38 is an average of 14%. The P-38F is slightly superior in the T/C category and this combined with the high Aspect Ratio probably gives it the edge in Cd for the wings.


re a developed Peregrin II engine.

The Peregrin I was slightly more efficient than the Merlin III in terms of HP/in3. If it had been developed further and given the same tweaks as the 'Hookerized ' Merlin, there is (I think) no reason the power could not have been similar to the Merlin 45 in terms of HP/in3 at +9 lbs boost - ie 0.73 BHP/in3. So a 'Hookerized' single-speed Peregrin II should give about 950 BHP at ~15,000 ft. This increase would give the Whirlwind a Power/Weight ratio of 0.181 HP/lb, basically the same as the combat ready F5F-1, and clearly superior to the P-38F.


NOTE All of the above obviously ignores the superior altitude rating of the P-38F with its turbosupercharger system. Presumably, the P-38 would steadily reduce any performance differences as altitude increases above 15,000 ft and probably surpass the Whirlwind and XF5F-1/F5F-1 at any altitudes above about 20,000 ft. With the later intercooler/turbocharger arrangements the Vmax for the P-38F was about 370 mph at 15,000 ft.

F5F really looks more and more like a missed opportunity...

 

[Mike Williams]

That! Is! A! Nice! Chart! I hadn't seen before. Too bad it's barely legible. Anybody got a better scan of that?

Maybe, see attached.

 

[Wild_Bill_Kelso]

Maybe, see attached.View attachment 712985

Thank you so much, definitely a much clearer image though still a bit tricky to read.... Put this one in your archive E eagledad

 

[slaterat]

The Whirlwind probably could have been improved enough to be a viable fighter in the first half of the war. In the end it didn't pass the test of limited resources allocation. The RAF fighter needs were met reasonably well by the
Spitfire/Hurricane, Spit 9/ Typhoon and the Spit14/Tempest combinations.

 

[MiTasol]

Great chart - interesting that the three Mustang versions had such different characteristics

 

[MIflyer]

Between the Mustang Mk I and the Mk III they revised the ailerons and increased the roll rate quite a bit. Farnborough came up with an aileron design that was actually a bit quicker but NAA chose their own design.

Never read that they retrofitted the Mk I and IA's but it would have been logical. They retrofitted the metal ailerons on the Spits, and in fact Johnny Johnson's unit contacted the aileron manufacturer directly and arranged to have it done to their Spits without seeking permission.

One day the phone rang at our office at OC-ALC, a call from Eglin AFB. They wanted to know if they could install F-106 aileron actuators on the PQM-102A drones to increase the manuverability. The hydraulics guys replied that they had no idea but to be sure and let them know how it worked. Not long thereafter the guys responsible for supporting the PQM-102A's started complaining that the darn things were lasting a lot longer than they should have and as a result were running out of spares; don't know if there was a connection.

 

[GregP]

Great chart - interesting that the three Mustang versions had such different characteristics

The P-51 ailerons could be rigged with differing deflections. Naturally, the one with the most deflection was the hardest to apply full ailerons to, especially at high speeds. Also, the P-51A had fabric ailerons and elevators. The P-51D had metal ailerons and elevators. Both retained fabric rudders. There is a marked difference between the two in rigidity when deflected into a several hundred mph windstream.

 

[Wild_Bill_Kelso]

They complained about ailerons and roll with the Allison engined Mustangs in China / Burma, but that seems to have been sorted out by the B/C

 

[Clayton Magnet]

I am sure everyone has seen this chart before, but here it is again anyway for reference

 

[GregP]

Thanks for posting it again, Clayton!

 

[SplitRz]

Maybe, see attached.View attachment 712985

At low speeds, beware the rolling Hampden?!

 

[GregP]

At low speeds, beware the rolling Hampden?!

I thought the Hampden had issue with full rudder deflection, not rolling. Perhaps I misremember.

 

[MIflyer]

Was the Hampden the one that had a problem with a tendency to fly sideways if left unattended?

 

[Just Schmidt]

Was the Hampden the one that had a problem with a tendency to fly sideways if left unattended?

As its nickname was the flying suitcase, I think maybe rather it had a tendency to end up in the wrong airport.