Got home last night and started hitting my available references regarding Hispano-Suiza engines and particularly as regarded "contract" built Hisso's. France (Mayen, Brazier that I know of), U.K. (Wolseley,Sunbeam that I know of) U.S. (Wright-Martin) were licensed to manufacture Hisso's. They all had their share of problems with manufacturing an engine that in many ways pushed the limits of available technology as well as manufacturing realities. There was quite a learning curve. In time many of the bugs were worked out- some weren't.
During the period of the war none of the licensed engines achieved the quality or the performance of the originals.Although there were also innovations developed by the contracters which in time improved the hisso's in particular and aircraft engines generally.
With the heavy demands put on Hispano-Suiza to produce engines for France to use in their Spads a Commonwealth pilot felt fortunate indeed if he was lucky enough to have an "Hispano-Hispano" powering his bus.
Wright-Martin produced fairly reliable contract engines but achieved this by derating the horsepower from 200 to 150. These engines were a performance improvement for the Jennys with a 90 hp OX-5. Good enough for a trainer. The French and the British could not afford to sacrifice hp in their prusuit aircraft and so were attempting to maximize the power potentials of the engine at the same time they were learning simply (or not) how to manufacture them in the first place. Broken crankshafts, compression leaks, failed bearings, ill-sized or ill-fitting cylinder sleeves, and warped valve stems were continual problems.A never-ending headache for the mechanics and a continual threat to the well being of the pilots. As if they needed to compound the risks they were already taking.
