Hi Umberto. Any ideas on a solution to this issue ?
There are two issues, which are not exactly the same:
- A small bump after disconnecting the towbar. This will happen regardless of the airplane, but it changes depending on the scenery, and it's due to the fact almost every airport in MSFS has some kind of elevation difference.
The way GSX pushback works, it freezes the airplane, but it doesn't disable the simulation, otherwise the airplane and the tow truck would proceed in a straight line, always at the same initial altitude MSL, because with the simulation disabled, they won't "feel" the terrain underneath. Also, disabling the simulation would disable almost all systems so, clearly, that's not an option. Instead, when the airplane is just frozen, it won't move during the pushback, so there will be no jittery due to fight between the flight model and GSX controlling it, but when the terrain changes elevation during the path, the airplane inertia system will register it so, at the end of the pushback, when it gets unfrozen, the altitude difference will catch up, causing that bump. We use some mitigation feature, like setting all the acceleration variables to 0 just before and just after unfreezing, but couldn't manage to remove it entirely. The issue is, if we didn't freeze the airplane during pushback, it you start engines, it's likely that just the movement caused by idle thrust might be enough to cause jitters, because two vectors forces would be fighting at each frame, the tow truck would likely slide as if was on ice, etc. We found that kind of bump to be a minor nuisance, compared to the alternatives.
An alternative might have been using the default Left/Right pushback events, like other default-based systems do, but that's not precise enough for what we need, since we couldn't control the position and especially the heading as finely as we can do now (small decimals of a degree), we would have a coarse Left/Right control that, since input events are processed only at 6hz, would probably always chasing the line, in addition of course to the aggravation of spamming simconnect with events, instead of setting data variables, which is way gentler to the simulation.
Having the option to raise the gear or not in Towbarless truck doesn't make any difference, once the airplane is frozen, it doesn't really matter if it's pitched up or not. We have a custom value that has been tuned manually to show just the right amount of pitch up, depending on the airplane, they don't react the same, it depends on their payload and the shockers compression value.
- Some reaction in the airplane custom systems.
That's a completely different issues, and it can be fixed completely once you'll see the first developers integrating GSX. They can detect when GSX is pushing and change any assumptions affected system about the airplane status, so it won't trigger any specific alarms.
