Any flight data that is gained after a rocket is launched will be lost if you go back to that craft (only for the engines that are still present of course).
Steps to reproduce:
Create 2 identical rockets (all stages single engines to keep it simple). Put one into orbit, leave it there. Put the next into orbit. Remember the du. Go back to the first rocket.
If you now build a new rocket, it will have the lower du of the first rocket. All data gained from the second rocket orbital stage(s) is now lost.
This does not require the engine to be fired or even to have any ignitions or fuel left. Simply by loading the craft, the current flight data value of the engine(s) will be saved globally. I may add, that according to the save game, the flight time is actually saved correctly, though I don't think that has any effect in game.
Any flight data that is gained after a rocket is launched will be lost if you go back to that craft (only for the engines that are still present of course).
Steps to reproduce:
Create 2 identical rockets (all stages single engines to keep it simple). Put one into orbit, leave it there. Put the next into orbit. Remember the du. Go back to the first rocket. If you now build a new rocket, it will have the lower du of the first rocket. All data gained from the second rocket orbital stage(s) is now lost.
This does not require the engine to be fired or even to have any ignitions or fuel left. Simply by loading the craft, the current flight data value of the engine(s) will be saved globally. I may add, that according to the save game, the flight time is actually saved correctly, though I don't think that has any effect in game.