I lately became interested in an issue with negative G's and inverted flight and if it affected the Japanese engines.
However both pilot statement and original documentation say that it was not a case, the earliest source I managed to find, was Type 99 950 HP engine manual (Ha-25 engine) and at page 25 it indicates:
"At the special flight situation drastic maneuver often excessively change the gravity applied on vaporizer hence float mechanism can work improperly, leaving composite gas density thinner and eventually stops the engine, so this vaporizer has worked out for adapting to those situation by setting fuel control devices such as gravity valve and flow restriction valve to make automatic fuel supplement available in order to facilitate the operation of engine during any kind of gravity change. "
This was my rough translation of this part :
Last part indicates that issue not only was known but is solved.
And indeed both Hayabusa or Zero pilots, including Saburo Sakai confirm that it was not a case.
However is it know, I'm especially asking Shinpachi since he might have first hand data, if that was a problem for earlier models like A5M4 or Ki-27 ?
