SpaceShipTwo: How it's Supposed to Work : Discovery News
Granted that this source is credible, it gets more confusing.
Initial analysis ruled out an engine problem. Instead, onboard video and data relayed during the flight quickly led investigators to conclude that for some unknown reason co-pilot Mike Alsbury, whose body was found in the wreckage, moved a lever that unlocked the spaceplane’s pivoting tail section early, before conditions were right for aerodynamic forces to hold it in place.
Once unlocked the tail is not held in place by the pneumatic system, but by aerodynamic pressure on the tail?? Or does it mean that the pneumatic system is not powerfull enough to hold it in place when arrodynamic loads exceed a given limit?
I tried to follow the logic in the patent, while the unlocking is explained in great detail, there is not that much info on the working of the tilting system itself, or I was not able to grasp it.
After SpaceShipTwo is dropped by its carrier jet some 50,000 feet above ground, its tail section, unlike the tail of a regular aircraft, is generating up-lift on the vehicle, rather than a downward force (which on airplanes counters the wings’ lift to generate stable, horizontal flight.)
Once its rocket motor burns out and its fuel is spent, SpaceShipTwo’s center of gravity shifts forward, so that the tail generates downward force, like an airplane. In between boost and re-entry, aerodynamics forces dictate when structural loads shift for safe reconfiguration of the vehicle.
Aerodynamic loads on the tail are not only influenced by speed (subsonic, transonic, supersonic) and altitude (less loads higher up), but also by shift of CG due to burnt fuel. According to the source that leads to a reversal of lifting force on the tail. after burn out. If I follow that logic, then the unlocking of the system would not only depend on the airspeed, but also on the remaining rocket fuel.
That must be a hell of a ride for the pilots to keep that ship pointed on the intended flightpath, now i understand these flight path oscilations some more.
Does that also mean, that unlocking the feathering system at 1.4M gives the tail some freedom to align with aerodynamic loads and thus helps in dampening the flightpath?
Any thouhts on that?