It is presumed that the leg linear velocity l does not contribute significantly to the horizontal velocity at liftoff.
There is no velocity discontinuity at liftoff and no discontinuities in the position variables at all for the onelegged hopper.
We also have imposed a lower bound on the trunk forward speed at all points, and bounds on the leg inclination angle at touchdown and liftoff instants.
Cryogenic propellants (liquid oxygen oxidizer, and liquid hydrogen fuel) need to be continuously topped off (replace boil-off) as scheduled liftoff approaches.
The cause of the crash was determined to be a premature liftoff, followed by a stall and mush into a 12-foot embankment.
Five seconds after liftoff, the left engine fire alarm sounded in the cockpit.
At this point, the volume of enemy fire intensified, hitting the helicopter and causing it to crash shortly after liftoff.
Four seconds after liftoff, the engine overheated and burned through its gas generator, severing an oxidiser line.
