Allison Engine development

[Karnak]

For why the engines have the places they do in the popular mind, look at the great WWII aircraft they powered:

Merlin:

P-51B/C/D
Spitfire
Mosquito
Lancaster
Hurricane


Allison:

P-38
P-40


Things like the P-39, Defiant and Battle are largely forgotten.

[Captain Virgil Hilts]

Originally posted by HoHun
Hi Squire,

>The engine itself was a fine design, but the US War Dept made a bad mistake by not insisting on two stage superchargers for those two fighters.

I think it would be  highly interesting to see an engine comparison based on shaft power instead of the usual brake power. That would eliminate the supercharger from the equation, emphasizing the performance of the basic engine :-)

Regards,

Henning (HoHun)

The problem with that is it fails to take into account what the engine was built for. Besides, the best way to test a piston engine is with a brake style dyno, be it water brake or eddy current. If it wasn't the best way, I wouldn't have spent $25K on a water brake dyno.

If you eliminate the crank driven supercharger, then it will be a test of which engine is built to use the least amount of boost, and therefore has the highest static compression. Neither the Merlin nor the Allison were built to be run normally aspirated, and as such had VERY low static compression, in the 6:1 range. You could run them on 87 octane lawn mower gas normally aspirated.

[Captain Virgil Hilts]

Originally posted by gripen
AFAIK the distance record was reached with a P-82B ie a Merlin powered twin Mustang.

From Baugher's site:

"On February 28, 1947, P-82B serial number 44-65168 piloted by Robert E. Thacker and his copilot John M. Ard flew nonstop without refueling from Hickam Field, Hawaii to LaGuardia Airport, New York, covering a distance of 4968 miles in 14 hours 31 minutes 50 seconds for an average speed of 342 mph. This airplane, named *Betty Joe* after Thacker's wife, carried four external fuel tanks under the wings for this flight. This was the longest unrefuelled flight ever carried out by a piston-engined fighter. The record still stands."


gripen

I stand corrected. However, I did not see a real reduction in range, and little actual reduction in speed, at the change from Merlin to Allison power, despite the fact that they derated the Allison. Too bad they never put turbochargers on the Allison powered twin Mustang, or for that matter put the Allisons built for the twin Mustangs into P-38's with decent props.

The supercharger on the Allison used in the twin Mustang could have been used on the Allison in the P-40, the P-38 (even with the turbochargers), the P-39, or even the P-51A. Only stupidity and arrogance prevented it.

[Angus]

"The Allison powered twin Mustang was able to exceed 470MPH, and to this day still holds the distance record for a prop driven piston engine fighter with no refueling."
Very interesting.
The Hawker Fury might as well hold an interesting record in covering distance, - i.e. London - Cairo with 1 (?) landing on the way, Pilot was Neville Duke.

[MiloMorai]

Originally posted by storch
great site just bookmarked it.  thanks for posting that.

If you can, you should see the Uboats run. Fantastic sight to see.

A couple of years ago, not sure what happened last year, but a twin turbo Allison won a couple of races against the turbine boats.

Virgil, what are your credentials for commenting on the Allison?

[Captain Virgil Hilts]

Originally posted by MiloMorai
If you can, you should see the Uboats run. Fantastic sight to see.

A couple of years ago, not sure what happened last year, but a twin turbo Allison won a couple of races against the turbine boats.

Virgil, what are your credentials for commenting on the Allison?

I used to work on Allison powered pulling tractors. I built several of those engines, and in doing so I got to know a few people who built them for Unlimited Hydro and airplanes.

[storch]

Originally posted by Captain Virgil Hilts
Only stupidity and arrogance prevented it.

a USDOD trait that is well entrenched and alive and well to this day.  the lateste example would be the premature retirement of the F14 from the fleet.

[Debonair]

there wasn't a DoD back then.
there could have been, Billy Mitchell had been after it in the 20s, but the old guard didn't want it.
iirc the Air Force (also Billy Mitchell's idea) was started up the same day as the DoD

[storch]

I'm aware of that never the less that trait was going on from long before and if there is a DoD 1,000,000 years from now it will be occurring then as well.

[HoHun]

Hi Hilts,

>If you eliminate the crank driven supercharger, then it will be a test of which engine is built to use the least amount of boost, and therefore has the highest static compression.

Hm, you're right. Maybe it would be best to list shaft power at full boost then in order to eliminate supercharger effects?

That would make it possible to compare engines with different superchargers as the altitude characteristics and the power required for driving the supercharger would not longer make the comparison as complex as when comparing brake power.

The problem is, of course, where to get the figures? :-)

Regards,

Henning (HoHun)

[storch]

Originally posted by MiloMorai
If you can, you should see the Uboats run. Fantastic sight to see.

A couple of years ago, not sure what happened last year, but a twin turbo Allison won a couple of races against the turbine boats.

Virgil, what are your credentials for commenting on the Allison?

I live in miami and was a frequent visitor at the miami marine stadium in the 70s and 80s.  once they started replacing the big allisons and merlins with JT3s I was done.  a whiny assed boat held no special appeal for me.

[MiloMorai]

storch, I agree the turbines are not as impressive, they lack the growl of the V-12s but still impressive none the less. The big American V8 powered hyrdos are more spectacular. Going to Valleyfield for the July 7 weekend to watch them.

In 79,I was racing at the MMS until I was suckered by the wind coming around the stadium and blew over backwards. Tunnels can be flighty.

This is the boat, in which I got Class SE Canadain High Points and damaged in Miami

[storch]

here's what the venue is like today.

http://spork.no-ip.com/~uef/gallery/marine_stadium/aao

[Ack-Ack]

Originally posted by Wolfala

Three other F-82's are known to exist. One has been a "gate guard" for many years outside Lackland AFB in Texas, while a second F-82B that had been on display next to it was acquired by the former Confederate Air Force in 1966 and was operated for many years by its Midland, Texas squadron. That F-82B stalled and crashed in Harlingen, Texas in 1987. The aircraft was restorable, but its unique props and landing gear were destroyed in the crash, and replacement parts could not be obtained. In 2002 it was included with the CAF's crashed P-38 in a trade for a flyable P-38. The Air Force has stepped in and is demanding the F-82 be returned since it was only loaned to the CAF conditional that they keep it. The matter is still being debated. A single fuselage of the second YP-82 was located for many years on the farm of Walter Soplata in Newbury, Ohio. It was sold several years ago and its current whereabouts are unknown.

Are you sure there isn't a 4th?  There is a F-82 in San Diego at Gillespie Field just outside of El Cajon that is about 90% restored to flying condition at the little CAF warbirds museum.


ack-ack

[Fencer51]

Originally posted by Wolfala
Three other F-82's are known to exist. One has been a "gate guard" for many years outside Lackland AFB in Texas, while a second F-82B that had been on display next to it was acquired by the former Confederate Air Force in 1966 and was operated for many years by its Midland, Texas squadron. That F-82B stalled and crashed in Harlingen, Texas in 1987. The aircraft was restorable, but its unique props and landing gear were destroyed in the crash, and replacement parts could not be obtained. In 2002 it was included with the CAF's crashed P-38 in a trade for a flyable P-38. The Air Force has stepped in and is demanding the F-82 be returned since it was only loaned to the CAF conditional that they keep it. The matter is still being debated. A single fuselage of the second YP-82 was located for many years on the farm of Walter Soplata in Newbury, Ohio. It was sold several years ago and its current whereabouts are unknown.

There is one on display at the United States Air Force Museum in Dayton Ohio.

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