Allison V-1710 F24 engine

[Piper106]

Does anyone have informations, specs, drawings, etc. of the unbuilt Allison V-1710 F24 engine???

On page 272 of "Vees for Victory", his authoritative book on the Allison engine, Dan Whitney states "this engine (F24R) would have used a newly designed integral two stage supercharger". That choice of words makes the F24 supercharger sound temptingly like a Merlin 60 series 'blower'. My speculation is an 'integral' two stage arrangement could be a much more compact package than the (fairly) well known two stage mechanically supercharged V-1710s using the Allison Auxiliary Stage arrangement.


I posted this earlier at secretprojects.co.uk, but thought there likely are some folks on this board that doin't get over to that forum.

 

[GregP]

The Allison Engine Company asked the US Government at least 3 times if they wanted a 2-stage supercharger to be designed for the V-1710 engine. The answer was always "No." So the government got what it asked for. Allison was a relatively small engine company and could not develop a 2-stage supercharger on its own without funding from the primary customer for the engine.

So ... the US Government got what they ordered, though the stock Allison V-1710 was and IS a very good, reliable engine. Our shop has several out there still running after 1,200+ hours and 15+ years with normal maintenance and normal carburetor overhaul at the recommended time. It is very strong and long lasting for a high-stress, liquid-cooled V-12. Lasts much longer than a Merlin if overhauled correctly to factory Allison specs.

Late-war Allisons were altitude rated at almost the same altitudes as the Merlins. There was little to choose between them in 1944-1945.

Maintenance was an issue. When jets came into vogue, the pistons were relegated to second-class status and were not well maintained.

The real-life second stage was the aux stage supercharger. Our shop has two ready for overhaul if anyone is interested. The 2-stage unit other than the Aux stage was never completed because the government never paid for it to be developed. Patriotism is wonderful, but significant development takes money, not good thoughts.

Gratis funding is never very prevalent and the integral 2-stage Allison supercharger was never funded despite being severely needed by the war situation.

Thank the legislators ... they were and ARE to balme.

 

[Aurum]

Here is the full history of this matter Supercharging Allison

 

[tomo pauk]

The full history is a ~470 page book, rather than 20-odd page pdf?

 

[Piper106]

To Greg P - My comments intended no ill will toward Allison. You are absolutely correct, the government/USAAF got what it paid for. I agree with your point, versions such as the E21, E22, the E30, the F32, and G6 with the Allison Auxiliary stage supercharger had performance at both low and high altitude at least comparable if not superior to the equivalent Merlin two stage engines (when running as designed).

To Aurum- I have read the referenced pdf, and it is very informative, but... not one word mentions the F24 version, which was the question in th original post.

My question had nothing to do with trying to change history, nor any attempt to degrade Allison. Hopefully everyone here understands that changing history is not possible.

That still does not change the interest trying to discover what Allison proposed as the supercharger arrangement for the F24 engine, if for nothing more than knowledge. .

 

[tftoc]

GregP

How did the Allison compare in terms of maintenance required during service to the Merlin?

What are typical Allison core and overhaul costs these days?

 

[GregP]

The Allison is easier to maintain by a reasonable factor. With a Merlin, you have to torque the cylinder liners every 25 - 30 hours. They are NEVER a maintenance item on the Allison unless a cylinder has to be changed. Then it gets torqued to 2,200 foot pounds. The Merlins are reasonable to run for a higly-stressed V-12 and I like the engine, but it is WAY more complex than an Allsion 1710. Neither partitularly leak and history has spoken ... the Merlin is a great engine. Unfortunately they tend to ignore the Allison which, to me, is just wrong.

The late-war Allisons were great performers, even on European fuels which we didn't have in the USA unless we imported it. Normal maintenance consists of carburetor overhauls, oil changes, filter and screen cleaning at intervals and proper starting and operation .... so does the Merlin.

Today, an overhaul for a Merlin can get to $250,000 US ... if they have the parts and they are becomming scarce ... not gone, but prices are incrreasing. An Allison can be overhauled for about half the cost and will deliver great performance for YEARS of reliable operation. I have one friend with a P-51D who got 40 hours out his freshly-overhauled Merlin ... until he found metal in the oil. Had a broken ring. He's back flying again, but the expertise is dying out.

Likewise for the Allison.

Right now, the best Allison overhaul you can get is from Joe Yancey in Rialto, California. Expect to get in line and wait a year, and you get an overhauled, run-in engine that has seated rings, is ready for flight, and will last a long time if operated per the Allison book.

Forget the book and go by "seat of the pants," and NO WWII V-12 will give good service.

Joe will gladly show you how to hook it up and run it, and YOU get to run the engine as long as you want. He can also supply props if required, and has some exhausts if you don't plus available accessories like starter, generator, etc. He has a variety of carburetors that are ready for overhaul.

 

[J.A.W.]

R.R. bought out Allison Aero?, but weren't they a G.M.[not small] subsidiary for a long time, what of the P-82 story, after the Packard Merlin licence ran out?
I'd heard that the V-1710 was 'New Deal' Govt paid for during the depression as a low altitude rated Zeppelin-type mill..

 

[GregP]

The Allison started out as an airship engine, but it was quickly upgraded to an aircraft engine. The firt aircraft Allison went into the XA-11A testbed by Vultee that later became part of Consolidated.

Here is the Vultee A-11:

and here is the Allison conversion to test the V-1710:

It surely worked, but it didn't exactly make for a good-looking airplane to convert an airframe designed for an air-cooled radial to take a liquid-cooled V-12.

 

[SaparotRob]

The Allison started out as an airship engine, but it was quickly upgraded to an aircraft engine. The firt aircraft Allison went into the XA-11A testbed by Vultee that later became part of Consolidated.

Here is the Vultee A-11:
View attachment 734743

and here is the Allison conversion to test the V-1710:
View attachment 734744

It surely worked, but it didn't exactly make for a good-looking airplane to convert an airframe designed for an air-cooled radial to take a liquid-cooled V-12.

Reminds me of the Fairy Battle.