Slack ... Open Rails train simulator has a display showing how many cars are pushing or pulling, and whether you're stretched or bunched. Perhaps it's a glitch in their braking simulation, but it seems like whenever the regular air brakes are used, the slack all runs in - the train doesn't stay stretched, even if the engine is bailed off and pulling a bit. And if it runs in fast enough you can get a bit of a kick showing up in the train speed :o. Is that normal and appropriate, or is a conversation with the developers in order?