SAI Ambrosini 403


Well-Known Member
Jan 27, 2022
Alicudi, Italy
So, since my island is still partially covered in mud and the volcano is kinda erupting I can't sleep and I decided to write a post about my favourite italian ww2 prototype.
Today I wanna share with you the SAI Ambrosini 403, a wood fighter plane prototyped during the ww2 because of the shortage of strategic materials for aircraft in Italy.
But was it any good? yes it was, it was actually better than the SAI 207, more agile, faster and cheaper than the 207, in fact the end cost of a 403 was only 96000 italians lire, that are more or less 32000 euros in nowdays money (with inflation and everything, according to istat).

this one in the photo is a SAI 207, it looks very similar to the 403, but the wings are actually very different, this ones were kinda small, resulting in a not so performance fighter.
Anyway, both the 207 and the 403 were equipped with an air cooled, supercharged, reversed DOHC V12 made by Isotta Fraschini, called "delta", I think due to the shape of the engine that really looks like the greek letter ( this one Δ ), I really like the engine, it was a 26L air cooled engine and made about 700hp, even if it was aircooled the back cylinders didn't suffer of overheating, or so it was told me during my visit at the museo nazionale Leonardo Da Vinci in Milan; the engine wasn't a regular v12 it had a "hot V" configuration, this means that the exhaust manifold was in the inside part of the V instead of the outside, so the exhaust can be directly expelled thru the belly of the plane, resulting in a sleeker and more aerodynamic aircraft. I didn't find much about the supercharger, I do know it was a monostadium centrifugal supercharger but I really can't find photos of it, even on the one they had in Milan it wasn't mounted.

This is the delta, very cool engine if you ask me, but I don't know a lot about aircraft engine so I really can't say if it was actually a good and advanced engine, btw this is the one that's exposed in Milan, very cool.

This is one of the few photos of the 403, if I remember correctly there's another one or two but one if them has a swastica on the white stripe.
Another good thing about the aircraft was the time used to build it, it could be built in only 6000 hours and whit basic tools.
During 1943 the very first prototype was completed and flown, everyone liked it, or at least they did until during one of the tests one of the wings broke, resulting in a crash were the pilot died.
Some scrap pieces od a 403 were later used by Arrighi (an Italian ace who flew in spain) after the war to build one of his first moto gliders.
I love this plane, my dream is to at least find some of the blueprints and maybe one day build one ahah, until then, I want to share with you one of the piece of italian engineering that I like the most.
What do you think about it? let me know!