FIAT A.S.8 ENGINE.

jerryw · 08-23-2008, 12:29 AM

The Fiat A.S.8 engine was designed and developed in Italy during the early years of WW2 but was not intended for combat use. Its function was to capture the outright air-speed record installed in a specially built aircraft known as the CS15.
The A.S.8 was a V-16 design with individual cylinders and 45 deg. between the banks. Bore and stroke were 140 X 140mm giving a swept volume of 34.5 litres.
As with the 24 cylinder A.S.6 seaplane engine, the A.S.8 was designed to turn counter-rotating propellers.
Info on the internal arrangements of this engine is hard to find. Did this engine have two, side-by-side crankshafts each driving a propeller or was it a conventional V-16; if so, then the reduction gears at the front must have been of unusual design?
Any information welcomed.

red admiral · 08-23-2008, 06:50 AM

It was a conventional V-16 and was used as a basis for the later A.38 engine.

jerryw · 08-24-2008, 09:37 PM

Thank you Red Admiral but can you provide any proof of what you say? One of the patents filed by FIAT SPA clearly shows a 16-cylinder engine with two side-by side crankshafts.
Also, if it did have just one crank, how did they provide the drive for the two propellers?

kool kitty89 · 08-25-2008, 02:55 AM

For the props it should be similar to what those used with the Griffon, R-2800, and R-4360 etc. were equipped with on various projects durring WWII and post-war. (XB-35, YP-60, Seafang, etc) I believe were geared to be operated by a single shaft.

red admiral · 08-25-2008, 05:53 AM

I'm pretty sure from the arrangement of the A.38 engine which was based on the AS.8. This was definitely an inline V-16 and also had contra-rotating propellers. The drawing of the installation of the AS.8 above also looks like an inline V16. The contra-rotating propeller has a single input which drives the rear propeller. Then there is a gearing system (could just be a simple bevel gear) that moves the drive to the opposite direction of rotation driving the forward propeller.

Do you have a link to that patent? I had a quick search but couldn't find anything like it.

jerryw · 08-25-2008, 09:24 PM

The only reference I have to the Fiat A.S.8 that gives some description of the internals is by Coggi (Italian text). I've had this translated - the account is a bit vague and is not accompanied by any drawings.
The patent is GB 360,167 which can be downloaded free from the Espacenet site.
Drawing attached shows basic layout of the A.S.6 (two 12-cylinder engines in tandem) and the A.S.8(?) (two straight-8 engines, side-by-side)

red admiral · 08-31-2008, 05:47 PM

Thanks for that. Its quite an interesting arrangement. Have you any idea why the compressor casing is shaped so strangely?

jerryw · 10-03-2008, 07:46 PM

Never mind the compresser shape, Rear Admiral - we are still waiting for you to substantiate your claim that this engine had only one crankshaft!

If you can't prove it, remove it!!

red admiral · 10-05-2008, 06:37 AM

I don't have a great deal of information on the AS.8 to give a definite answer one way or the other. If the angle between the banks is 45° as in post #1 then I'd guess that its a conventional V16 as this is a nice balance angle for the arrangement and the angle between the banks in the patent drawing is not 45°

kool kitty89 · 10-05-2008, 08:01 PM

Looks to be about 30° in the patent.