Compressibility modelling

[Holtzauge]

When diving under power aircraft speeds should be limited by compressibility effects. If not then aircraft that utilize vertical tactics like BnZ will get an unfair advantage over aircraft that employ angles tactics.

If airspeeds in the dive are not limited by compressibility, then the energy retention will be too high and an aircraft doing a BnZ attack will end up at to high altitude following a dive and zoom.

I don't know how/if this is modelled in the sim but I think this could be tested implicitly by comparing airspeeds from a test dive in the sim with the attached C++ simulation chart. The chart contains two graphs:

One is for the Spitfire Mk1 at +6.25 boost with compressibility modelled, both in terms of compressibility drag rise and also reduction in propeller efficiency due to Mach effects. The other has no compressibility correction whatsoever, either on drag rise or propeller efficiency. Both start from 23,000 ft altitude and 336 mph TAS.

In IL2 there was something called "devicelink" where one could extract this type of info and do a comparison. Don't know if this or something similar exists here. An alternative is of course simply to test dive and read off the speed at 2.5 Km altitude 61 s into the dive and see how this compares with the sim. If there is no way to read out TAS in the sim then I suppose one could convert the IAS cockpit reading if this is reliable enough.

I don't have the hardware to run this sim so I cannot test myself but I'm curious to know how the sim handles high speed dives.