Air War Over Khalkin Gol - Altitude Ratings

I've started to play around with the numbers for the Wings at War Khalkin Gol / Nonomhan rules re-writing project, starting with the relative altitude performance of the aircraft for both the Japanese and Soviets. This is a simple matter of taking the maximum service ceiling for each type and then comparing it to a series of four height bands, up to a limit of 12000 metres, above which none of the aircraft could fly.

The overall result is a table that looks like this (give or take a few adjustments and with some of the transport aircraft omitted, as they would play no part in the game):

This seems like a fair representation of the relative altitude performance of the different aircraft for both sides but I now have to do the far less straightforward calculations for the Energy Ratings, both loaded and unloaded, which will be a little bit more involved and likely to result in some head scratching, especially as I can't use thrust to weight ratios as a starting point this time round. I'll just have to work out a different mechanism based on wing loading, take off weight and speed.