The Fiat G 56

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Ah, the G.91. It was a much maligned aircraft at the beginning (mostly by French, who lost the NATO competition for a lightweight fighter ). It was said to be a scaled down copy of the Fiat F-86K (a Sabre licensed design adapted to local production) but, probably, it was more a case of convergent evolution. Italian designers started to tinker with jet engines even during WW2 and, in any case, the G.91 wasn't the sole Italian swept wing aircraft that entered the NATO competition.

Gabrielli himself had been a student under Von Karman, so he must have known a thing or two about aircraft design The G.91 could go supersonic in a shallow dive at altitude and was very agile. In terms of combat capabilities, I would rate it between the Mig-15 and the Mig-17. The Italian version was armed with four .'50" machine guns, the German version with two 30mm Aden cannons and four hard points. (usually the inner two were always occupied by a pair of 260 liters fuel tanks). Each hard point could host around 250kg of ordnance, the most common being a free fall bomb or a small rocket launcher. The G-91 'PAN' aircraft used by the Italian Acrobatic Team were the first production run, with an elegant pointy nose. The subsequent versions had a 'fat' nose with three recon cameras in it.
 
I believe the Folland Gnat was also in the same competition.
They both use the same engine.
The Gnat predates the G.91 and was not evaluated in the competition, though it might have inspired it. (Or maybe it was an answer to the Easter block which was flooded with rather crude but effective jets like the Mig 15 and 17).

They both used the Bristol Orpheus turbojet, which -at the time- was the jet with the best thrust to weight ratio, and also one of the simplest, least expensive (Bristol said, it would have been possible to build them in quantities at £500 apiece - that's something like 20000$ of today). It was as powerful as the RR Nene but weighted less than 400Kg and was very compact. The mean time between overhauls was low (around 150hrs in the first version; the FIAT made unit mounted in the G.91 was around 300hrs, if memory serves me right) but still very cost effective and reliable.

 
I read somewhere, long ago, that Petter refused to put bulged landing gear doors on the Gnat which would have been needed to accommodate the size tires needed to meet the NATO Field requirement (grass air strip?). There may have been other requirements He did not want to change the design for? This would have knocked it out of the running well before any fly off took place.
I think it was something by Bill Gunsten but could be wrong. Doesn't mean he was right either.
 
I dunno if it was a requirement, but the G.91 had .25" armor plates protecting the cabin and the engine against small arm fire from below. That also explains why it's quite heavy (around 3 tons empty) despite the diminutive size.

As for the requirement to operate from semi-prepared airstrips, the G.91 had indeed low pressure tires and a strengthened gear. Tyre dimensions are 640mm (dia) x 240mm (width) for the main gear wheels and 430mm x 170mm for the nose wheel.

I found an interesting picture of the G.91... supposedly this was taken in the late '50s. I thought the US Army had ceased to operate fixed wings aircraft after 1947. It's interesting that they evaluated a tactical support plane like the G.91

 
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I found an interesting picture of the G.91... supposedly this was taken in the late '50s. I thought the US Army had ceased to operate fixed wings aircraft after 1947. It's interesting that they evaluated a tactical support plane like the G.91

The US Army received two G.91Rs and one G.91T two-seater for evaluation in 1961, trials taking place at Fort Rucker and Kirtland AFB for a tactical strike aircraft. I read that trials were suspended when two of the aircraft crashed.
 

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