This basically works (the contactpoints being all in the negative was a bit confusing):
[launch_assistance]
//Nose Gear
//point.0=1, -21.00, 0.00, -7.50, 2000.1, 0, 0.6349, 46.8, 0.8000, 1.5, 0.5100, 10.0, 10.0, 0, 260.0, 260.0
launch_bar_pivot = -19.80, 0.0, -4.37
launch_bar_lug = -20.20, 0.0, -4.43
It may need a bit of tuning to keep the nose wheel down while launching...
U does nothing.
I arms lauch assist and blast deflector
launches
Wim