Spaceship One Test Flight Anomolies

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."

Comments

The value of testing.

[LWATCDR]

This could have killed someone. This shows the value of a well thought out test program. I wonder if any other X-Prize teams are testing abort situations and CG limits?

How is this different from any other plane?

[dougmc]

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.)

Re:How is this different from any other plane?

[BigBir3d]

I am surprised that a poster with such a low ID number would resort to using logic to analyse a linked to article. I commend thee. </sarcasm>

And it happens to be that you are nearly 100% correct.

I was intrigued by the lack of understanding with respect to drag and gear door (seams I presume). Wasn't this sufficiently studied in the 1950's? *sigh* Geeks just love to learn it again for the first time I suppose... ;-)

One would hope that these new aero aids that are going to be implemented to keep the nose from coming up on its own will not be 100% necessary. What if they break, and the aircraft is in a overly loaded state? Your average space jockey (not that those exist yet) is not going to be as responsive, or understanding, as last month's test pilot was. This sounds like a dangerous path to go down. Any modern fly by wire aircraft should revert to level flight assuming most of the aero parts are intact, and the pilot is giving zero input (hands and feet off condition - as if passed out). Doesn't sound like this pig can do that. Bad design decision. Makes me think of all the other short cuts that were possibly taken.

Re:Bummer, but hey they still beats the shuttle.

[florescent_beige]

Re: "this continent" Not necessarily: Da Vinci and Canadian Arrow

IF there were no problems at all

[Zachary Kessin]

If there were no problems at all in testing I would be worried. Burt Rutan is pushing the limit here. When you do that you should hit a few snags. Its not a bit deal that is why you do a lot of flight testing. If you look at the test logs it is very clear that Rutan et al have a well thought out flight test program. And they are running it. From everything I know they have people who really know their stuff.

They will fix this problem, and I'm sure they will find a bunch of other ones and then they will fix them too. If i were a betting man (and I'm not) I would be putting my money on scaled to win the X-prize.