Author Topic: Space Ship Two - General Thread (3)  (Read 183007 times)

Online abaddon

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Re: Space Ship Two - General Thread (3)
« Reply #740 on: 06/01/2018 02:34 PM »
Haha. Silly me, I thought the feather system was all that was needed for correct orientation on re-entry.
You don't want it rotating around randomly while it is outside the majority of the atmosphere before descent.  Not a fun experience for the people on board, even if the feather works as advertised for the "care-free re-entry".

Glad to see them progressing, although that engine starting always gives me the willies, it always looks so rough.
« Last Edit: 06/01/2018 02:35 PM by abaddon »

Offline Elmar Moelzer

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Re: Space Ship Two - General Thread (3)
« Reply #741 on: 06/02/2018 02:33 AM »
Looked like a bit of pitch instability both at the end of the burn and at the beginning of the feather.

Of course, it could be deliberate inputs by the pilot to assess handling and control authority.
I noticed that too. I thought it looked a bit "wobbly" for the lack of a better word. Not sure how important that actually was though. Could have been deliberate testing, or maybe it is something they can fix easily for the next flight.

Offline cscott

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Re: Space Ship Two - General Thread (3)
« Reply #742 on: 06/02/2018 02:43 AM »
I'm torn on that. Nothing in the SS2 testing to date seems to point out a problem with stability. Have you heard something different.
The very fact that they are gradually moving the CG aftward indicated they are concerned about stability in the full-aft flight condition.

OTOH, the burn should move the CG forward, so it's not entirely clear why instability would show up at the *end* of the burn.

Offline Gliderflyer

Re: Space Ship Two - General Thread (3)
« Reply #743 on: 06/02/2018 03:43 AM »
I'm torn on that. Nothing in the SS2 testing to date seems to point out a problem with stability. Have you heard something different.
The very fact that they are gradually moving the CG aftward indicated they are concerned about stability in the full-aft flight condition.

OTOH, the burn should move the CG forward, so it's not entirely clear why instability would show up at the *end* of the burn.
Part of flight testing includes exploring all corners of the flight envelope, including aft CG. I don't have any inside information, but I view moving the CG aft as just a normal part of flight testing; they are probably concerned about it, but most likely no more than on any other aircraft.

As for the wobbling at the end of the burn, they are starting to run out of Q at the altitudes they are reaching so the flight controls will start to lose effectiveness. The nozzle is also ablative, and it is possible that it is not eroding evenly. That being said, it didn't look that bad and it will probably be fine.
I tried it at home

Offline Kabloona

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Re: Space Ship Two - General Thread (3)
« Reply #744 on: 06/02/2018 05:46 PM »

As for the wobbling at the end of the burn, they are starting to run out of Q at the altitudes they are reaching so the flight controls will start to lose effectiveness.

 Pegasus has a similar problem with the fins used for aerodynamic control. Near the end of stage 1 burn, dynamic pressure drops too low for the fins to maintain pitch control, so the fins have small solid rockets built into them. The fin rocket motors then ignite and provide the pitching moment.
« Last Edit: 06/02/2018 05:47 PM by Kabloona »

Online FutureSpaceTourist

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Re: Space Ship Two - General Thread (3)
« Reply #745 on: 06/05/2018 08:15 PM »


As well as Branson talking about the last flight, VG and his training for his flight, some bits of extra footage of the last flight I donít recall seeing before.




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Time for a new thread:
https://forum.nasaspaceflight.com/index.php?topic=45869.0
« Last Edit: 06/19/2018 12:49 PM by Chris Bergin »

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