Hi Sun,
Thanks for the report.
The reason behind is IL-2's simple and unrealistic engine overheat code in combination with a set of questionable parameters for the Merlins of these late war Spits.
In IL-2, regardless which version, you can run an engine in overheat condition for as long as this has been specified in the engine model.
In case of the Merlin66 in UP3, this time is set to 280 seconds (4 minutes and 40 seconds).
Once your engine is in overheat condition, the time counted since overheating began is compared to that threshold and once it's been passed, engine damage will occur.
However in case of the late war spits, they're equipped with automatic radiators and the game will open up radiators in time, so that before the 280 seconds have passed, you will see a message "Engine: Normal" flicker for a split second.
That's when the overheat stops.
Unfortunately in IL-2's game code any stopped overheat will
immediately reset the overheat timer.
This means you can run in overheat condition for 279 seconds, then cool down the engine so it's back "normal" for 1/10th of a second, then overheat it again for another 279 seconds and so on...
Overheat parameters differ much between different IL-2 versions and engine overheat has been changed from 4.10.1 to 4.11 (but mainly just in that high RPMs cause faster overheat, which was TD's way to fight all the upcoming modded jet planes), but the basic issue remains.
Two countermeasures apply:
- Change the engine's temperature settings to allow it to overheat at all.
- Change IL-2's overheat code completely to make it more realistic.
This would require all engine models to be changed.
Best regards - Mike