Spaceship One Test Flight Anomolies

Posted by michael on Tuesday October 7, 2003 @09:11AM from the teething-pains dept.

Marc Newman writes "Aviation Week reported that Scaled Composites had some unexpected flight anomolies on it's 23-Sept-2003 flight test. The test was conducted with an aft Center of Gravity (CG) and produced some unexpected nose up pitching. They were able to maneuver out of the stall with lateral motions. They also had much higher than expected drag from the newly installed gear doors. They described the pitch up motion as serious, as some abort scenarios leave the vehicle in an even worse aft CG situation than this flight (they can dump oxidizer but not fuel, and the fuel is located aft). They indicated that this lack of pitch control would 'require changes'. It's not expected that they will be able to meet their goal of a flight into space by the end of the year. There is a flight log and there is an article in this week's Aviation Week and Space Technology but it's not showing up on their web site yet."

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How is this different from any other plane? by dougmc · 2003-10-07 10:42 · Score: 3, Interesting

All planes become very difficult to fly when the center of gravity gets too far back. (On the other hand, if the center of gravity goes too far forward, the plane becomes extremely stable, but loses maneuverability and efficiency. If it goes *too* far forward, you may not be able to even keep the nose up. But as a rule of thumb, too far forward is much better than too far back.)
If the center of gravity goes far back enough, the plane becomes unflyable. Not quite so far back, the plane may be very difficult to fly (requiring that the pilot `stay on top of it', and if it gets into a spin it may not be possible to recover from it.
Aerobatic planes and planes that are trying to make very long trips on limited fuel (like the Spirit of St. Louis) will keep the center of gravity a further back than most -- but not too far. In a trainer, you usually keep it a bit further forward than usual to enhance the stability of the plane.
How is this different than any other plane? They intentionally set the center of gravity too far back, and it flew poorly. They should have anticipated this (and I suspect they did, and this isn't as big a setback as expected.)