[Graham Boak]

Wasn't Oberst Petersen a maritime specialist? Or was that a different Petersen? Not a name otherwise associated with fighter development, to the limits of my knowledge. He did have a command in the Rechlin structure, IIRC, so it probably is the same man.

Once we get to comparisons with DB603 we are in dream land. Each German manufacturer was desperate to get his hands on the DB603, and each believed that his fighter/bomber/zerstorer/aufklarer would be better than those currently in service, if only it had access to the supply of this more powerful engine. Probably correctly, but the engine was not fit for mass production and never reached more than a small fraction of the numbers desired. Had the engine been available in greater numbers there were many German types that would have had higher priorities than the Fiat.

Yes, a G.55 with the DB603 probably could have become a better aircraft than those in service in 1943 (though bear in mind that foreseen improvements often fail to materialise in hard engineering). However, this is hardly surprising, as the aircraft could not have become available in numbers before mid 1944 at the earliest, and has to be compared with aircraft available then or on offer in the same timescale. Particularly the Bf.109G-10 and K, the Me.209 and several options in the Fw.190/Ta.152 development line.