FIAT A.40

[Nico]

Dear friends,
during a search of some types of military vehicles, I explored the biography of Dante Giacosa (known for being the "father of the 500"). Eng. Giacosa was one of the directors of FIAT technical staff and he was also involved in aircraft engines. In his autobiography, albeit with some imprecision, we read that in 1940-1942 the Department of the Air demanded an airplane engine with high performance and Eng. Antonio Fessia named Eng. Carlo Felice Bona, Director of the Avio Engines, in charge of the development. This engine was to have a V16 layout and deliver 2,000 hp at 8,000 m.
I think he was talking about the A.44 RC.15/45.
But Eng Giacosa thought that his staff could provide an alternative configuration and designed a 24-cylinder X engine with four banks of six cylinders each (at 90°), compatible with a 20 mm cannon or a 12,7 mm machine gun firing through the propeller shaft. The engine was called FIAT A.40 (I never heard of before) and technical drawings are dated January 22, 1943. No photographs are known. Giacosa says that two prototypes were built but never bench-tested.
Of this unknown engine Giacosa includes two views that I attach.
Anyone of you knows something about it?
Nico

 

[Apophenia]

Interesting. Thanks Nico.

Other sources list the A.40 as a 1900 hp X-24 A.42 alternative. So that fits.

The A.44 RC15/45 was an evolution (and/or re-designation) of the A.42 (possibly abandoning the plan for A.38 cylinder banks?). The A.44 was to put out 2400 hp but with all the added complexity and weight of a 32-cylinder engine!

 

[Nick Sumner]

Apophenia, what are good sources for information on ww2 era Italian engine projects? Sources in English or Italian would be welcomed.

 

[Skybolt]

Well, I have to intervene from my retreat...
The A.44 was an H-32. It was designed in circa January 1941 (only known complete drawing is dated March 21st 1941) as a two generation-leap successor to the utterly failed A.38, meant to compete with the successor of the DB601-605 (DB603) series, by then assumed to be license manufactured in Italy. A.44 used the cylinder banks of the A-38. I don't adhere to the common interpretation that it was a coupled engine (i.e. two complete engines assembled one inverted on another).... like the various DB designs.
During the design phases, probably still smarting from the A.38 rejection and failure, Dr. Ing.Fessia asked Giacosa to develop a backup (this probably was in late spring 1941). Giacosa thought about it and finally decided to go for an X architecture. The cylinder was the same of the A.38 (bore and stroke) First official information and drawing is dated 15 December 1941 (been published on Ali Antiche some years ago, I think Hesham had it posted in another thread). I suspect Giacosa was influenced by the then in testing DB-604, and X engine that looks very similar to the A.40. There are some hints that at least the DCGA knew of the DB-604 n the 1940-41 timeframe). The DB604 was cancelled in late 1941, probably because the DB.603 by then was deemed succesfull (less weight, less bulk, less frontal section, same power). BTW, the A.40 was at some time renamed A.42, unknown if due to some modifications.

 

[Skybolt]

Here's a fine side and front view that complements nicely the drawings posted by Nico.

 

[Skybolt]

And the DB604 for comparison

 

[Skybolt]

In the very new "Il motore Aeronautico FIAT" by Francesco Greco, published by Gli Archivi Ritrovati (i.e. Paolo Miana) there is very faded complete drawing of the A-40. Print too small and lines too faded to hint the drawing date. If someone has the original or a better scan, could possibly post the date here, please.

 

[Nick Sumner]

Hi Skybolt, is the drawing of the Fiat A.40 in "Il motore Aeronautico FIAT" different from the one posted in reply 5 of this thread? Also does the book have much new information about other Fiat projects like the A.44?

 

[Skybolt]

No Nick, it is identical (from the exterior). It is printed upside down, so it may result somehow disconcerting at first. See by yourself.
As for the H.44, nothing new. The interpretation as a double-engine (a là DB.606) in repeated. No drawing (not surprising.. eheh).
Nothing more in the way of new material.