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Airplanes, Rocketry, Missiles, Spacecraft and things that go WHOOSH! in the night.
What's flying around my head at the current time.

Tuesday, July 20, 2004

More X-Prize News 

Found this on the rec.models.rockets newsgroup:

Canadian rocket team readies for space

July 15 - Canada's Brian Feeney says his Da Vinci Project staff is ready to challenge SpaceShipOne for the Ansari X-Prize and expects to roll out his more conventional-looking rocket (compared to aircraft-like SpaceShipOne) the first week of August. Feeney, who has aerospace and rocket design experience, plans to ride the rocket himself when it lifts off from Saskatchewan later this year. The rocket is powered by laughing gas and paraffin and is launched from a helium-filled balloon after reaching 80,000 feet.

SpaceShipOne to try for space prize

July 14 - Scaled Composites officials say they have found out what caused the trim problem and are ready to make a try this fall for the $10 million Ansari X Prize that goes to the rocket team reaching theedge of space twice in two weeks. Look for an official announcement at Oshkosh concerning the team of Paul Allen, who funds the project, and Scaled Composites. SpaceShipOne will fly with one pilot and lead ballast representing the weight of two additional 198.4-pound people and make the flight to 100 kilometers (62.1 statute miles) twice in a two-week period. The trim problem wasn't really a problem, Scaled Composites officials discovered. A left and right roll due to wind shear got SpaceShipOne off its proper pitch profile, called the pitch schedule. To get the craft back on the proper path, full trim was used that ran the pitch tab against the stops, causing an automatic 3-second time-out. After that it would have worked normally, but ground controllers, thinking it had failed, went to a backup system. In fact it had worked as designed.

They found out the source of the "loud bang" which was heard during the flight, and the cause of the dented panel. The dented panel probably was the source of the bang. Just like anytime you
buckle a curved shape inwards, like say a metal can, you get a big noise out of it. The dented panel was a brand-new fairing that was added between the original blunt end of fuselage and the big red nozzle which was visible in the earlier flights. On the last flight, the red nozzle was not visible, as it was covered over by that new fairing. That fairing’s purpose was aerodynamic, not
structural. It could have ripped completely off at that point and not directly have been a problem. Though if it veered left or right and hit one of the tailbooms that could potentially have been a serious problem (Rutan’s spaceships are no more designed to take significant debris impacts than NASA’s).

The underside of that fairing had buckled inwards (upwards). Looked like it was near where the structural fuselage (inside) ended and the nozzle began. Most likely the pressure during the extremely high angle of attack re-entry phase made it buckle. So they'll probably do something simple like adding an internal brace/stringer/rib or add some extra layers of composite materials to stiffen it up in that region.

Something else could have contributed to the buckling. The heat during the re-entry phase may have temporarily softened the resin enough to allow the underside of the fairing to buckle inwards more easily than normal, and since it is a part that’s meant for aerodynamics than structural they may not have accounted for the stresses on it or its weakened state when hot.

Space Ship One isn't seeing anything like the heat of reentry from orbit, but Mach-3 or so gets things pretty hot for awhile considering it’s an all-composite vehicle (fortunately it’s not going that fast in the atmosphere for very long, and slowing at many G’s once it hits the sensible atmosphere coming down). This may explain the dull red stuff they added to the leading edges, which would seem to be some added form of heat protection.

From an interview on pilot Mike Melvill gave on Today:

NORVILLE: There was, as you said, one little problem. And I gather it had something to do with the solid rocket in the fuel, where there was a big boom and for a moment you didn‘t know what had happened.

MELVILL: That‘s correct. There was a loud explosion and a large vibration as part of the fuel that‘s in the rocket motor went out through the nozzle and jammed the nozzle for a split second and then the pressure built up and blew it out.

So there was a very loud explosion, a lot of shaking going on, and I wasn‘t sure I hadn‘t lost part of the aircraft at that point. So that was scary for me.

Most of this was written by George Gassaway, and added to by others.

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