Thanks. It was literally a Homer Simpson moment. There I was, working on bands anyway and … D’oh !! JWE no function beer well without.ORIGINAL: sandman455
So ingenious, wish I had thought of it. [:)]
Looking forward to seeing your final results.
Japan has some planes that are extremely maneuverable up to 15k, highly maneuverable to 20k, moderate/good maneuverability to 30k. Most gasp for air above that. It would seem that the earlier Japanese two stage superchargers had a lowblo critalt of between 6 and 10000 and a highblo critalt of between 15 and 17000. The later engines and superchargers had a lowblo critalt around 10000 and highblo critalt around 20000. Some ‘high altitude’ interceptors had tweaked superchargers that could maintain ‘rated’ power (but a skoosh less than the ‘normal’ engine) up to 25000.
Similarly, US planes have good maneuverability all the way to 20k, and the later ones have exactly the same range of moderate/good maneuver as many Japanese in the 20-30k band. The early US engines had a lowblo critalt around 10000 and a highblo critalt around 15-18000 (ct, P-39/40). Later US engines had nominal highblo critalts of around 25000. Although US plane weights were considerably higher than their Japanese counterparts, their compensatory nominal engine power output was higher as well, especially at the higher altitudes.
Comparative numerics are working great. At moderate altitudes, the Japanese are seriously competitive, although they do break more easily. From 20k to 30k, things look a bit more equalized; the speed function is rearing its head, so some of the “speed” tweaks we made will have ‘some’ IJ planes be competitive in this regime as well. Think comparative performance at altitude is pretty well done.
The witch, of course, is what happens at the ‘beyond critalt’ altitudes. Ok, so there really is a model for this, for ‘mechanically’ supercharged engines: Normal power fall-off after CritAlt as a function of density (hemi, demi, semi, inverse square) going to the 100 fpm ‘service’ altitude. This power plot is then used to obtain the ‘practical’ ceilings for various planes. For fighters, etc.. it is what is generally considered the ‘combat’ ceiling – around the 750-1000 fpm limit. For ‘interceptors, it’s around the 250-500 fpm limit. And it works: It is a beautiful thing.
It works perfectly with planes having turbo-superchargers. Very Hi Alt maneuver, speed, etc.. Looks like we got something here.




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