I don't know how accurate you can get this, as there are variables that are going to be ever changing. As Dick Hanson remarked, an engine doesn't unwind as well on a dragy airframe as it does a light, clean airframe. Added into this is the humidity conditions. We have all flown our planes at times when the high humidity not only affected acceleration of the engine, but also how agile the plane felt. I assume that even if the engine were not affected by the humidity, the ability to pull the airframe changes as humidity fluctuates. By no means am I putting your efforts down, I greatly appreciate your efforts to get closer than what Thrust HP is. When I flew smaller planes, I used to think it could be used as a benchmark, but now that I have a few larger planes, I have not found it to be useful at all.

Are you able to incorporate relative humidity and altitude into the equation? Is there any way to clasify each aircraft, not just by sqaure inches, but by the thickness of the wing and the planes weight? Just food for thought...

Andy