Virgin Galactic Spaceship Two Unveiling

[yak52driver]

Spaceship Two will be unveiled this Monday. That would be an interesting 'aircraft' to pilot. I hope the pax numbers they project are met and they are successful with this, I think the privatization of space flight will be a key component of the future.

http://www.space.com/businesstechnology/091204-virgingalactic-spaceliner-ready.html

 

[desertoasis]

This will be something exciting to watch in the next few decades; the transition of space travel from a primarily scientific venture to a shared tourist/science environment. Should be fun.

(Any bets on when some nation is going to try to have a military presence in space?)

 

[yak52driver]

This will be something exciting to watch in the next few decades; the transition of space travel from a primarily scientific venture to a shared tourist/science environment. Should be fun.

(Any bets on when some nation is going to try to have a military presence in space?)

I agree that it will be exciting. I need to polish up my resume for a pilot slot!

It will be interesting to see what military involvement evolves. There's already the unmanned military hardward, spy satellites, GPS farms, etc, but I'm sure they are looking at Tier Two (orbital vehicles) as a possible 'cheap' means of rapidly launching a manned vehicle. Imagine the 'Ready 5' Spaceship Two variant...

 

[ryan1234]

I agree that it will be exciting. I need to polish up my resume for a pilot slot!

It will be interesting to see what military involvement evolves. There's already the unmanned military hardward, spy satellites, GPS farms, etc, but I'm sure they are looking at Tier Two (orbital vehicles) as a possible 'cheap' means of rapidly launching a manned vehicle. Imagine the 'Ready 5' Spaceship Two variant...

It would be interesting to see a space based strike group being able to get to any target in the world in 3 minutes!

 

[yak52driver]

SpaceShip Two Rolled Out

Virgin Galactic and Scaled Composites rolled out SpaceShip Two and White Knight Two to the press and VIPs. Pretty cool video, I'm pumped to see the test flights start.

http://www.virgingalactic.com/

I'm curious how they overcame some of the problems that SpaceShip One experienced. The biggest one that comes to mind is when it snap rolled on Mike Melvil and continued to roll over 30 times when he went to a very low alpha during the climb. That guy has big brass ones, rather than abort he kept the rocket firing and made the altitude.

 

[nittany03]

I'm curious how they overcame some of the problems that SpaceShip One experienced. The biggest one that comes to mind is when it snap rolled on Mike Melvil and continued to roll over 30 times when he went to a very low alpha during the climb. That guy has big brass ones, rather than abort he kept the rocket firing and made the altitude.

Flight control issues, or just a weird departure mode?

 

[FlyBoyd]

It would be interesting to see a space based strike group being able to get to any target in the world in 3 minutes!

I'll assume you mean manned right? I am pretty sure we got some crazy secret squirrel shit up there right now.

3 minutes might be a little quick though

 

[yak52driver]

Flight control issues, or just a weird departure mode?

Well, I guess it depends on how you define it. In intereviews with the engineer that designed SpaceShip One they said that as it got into thinner air the flight control surfaces become less effective. (yes, stating the obvious) Their challenge is they didn't use reaction rockets for attitude control and they don't gimbal the engine, either. After Mike Melvil's little 'excursion' they waited to damp out the roll rate with reaction thrusters until after he had shut the engine down and he was coasting upward. The reaction jets are basically high pressure air fed from a 'scuba' style tank, although at higher pressure. The departure was due to the low alpha, not sure if more effective flight controls would have avoided the ride he took. I don't pretend to be an expert on this stuff, but it's damn cool stuff and it would be kick a$$ to fly that thing.

 

[nittany03]

Yeah, I quit aerospace engineering after a smemester and a half, but I know low alpha environments often come with NATOPS restrictions due to weird inertial stuff. Not enough of a geek to know why, or at least the wrong type of geek.

 

[PropAddict]

low alpha environments often come with NATOPS restrictions due to weird inertial stuff

Huh?

Are we still talking alpha=Angle of Attack? Or is "alpha" different in the spacecraft usage?

Low Alpha is where planes (especially fast movers) prefer to live. High alpha is when bad things usually start to happen. . .

EDIT:

Looked it up myself.

SpaceShipOne Flight 16P Anomaly:
Highly publicized in the media, the rolls near the end of the motor burn certainly got our attention. Detailed analysis determined that the rolls resulted from a mild thrust asymmetry, which was unable to be offset by pilot inputs at a flight condition of low directional stability. This flight condition had not been tested on previous flights. The low directional stability occurs only at high mach #’s and at very low (zero or negative) angles of attack. On earlier flights the aircraft still had some lift at high mach numbers and did not approach the low angle of attack regime. On 16P, because Mike did such a great job of turning the corner early in the burn, the later segments of the burn had to be at near zero lift to point the trajectory in the desired direction. At this condition around mach 2.7 the airplane was excited in yaw and then the high dihedral effect resulted in a rolling departure from controlled flight. The fix to this problem that allowed a smooth boost 5 days later on 17P, was to fly a slightly less aggressive initial pull-up. This allowed Brian to avoid the low angle of attack regime when at high Mach. The characteristics of excessive dihedral effect and high-Mach low directional stability will be corrected on future spaceship designs.

Makes sense now. He was at zero lift AoA, in a high-supersonic flight regime. The wings and ailerons weren't doing anything for him and from the pictures, his vertical tails are too small for that flight regime. Throw in some asymmetric thrust, and you now can't point your own nose anymore. This made it lose weathercock (directional) stability, then the dihedral of the wings tried to correct the perturbation. The cross-coupling of the two was bad juju.

 

[MasterBates]

There is also low alpha regimes where you unload the plane.. As in very little AOA, and weird shit happens there for inertial reasons.

 

[yak52driver]

Huh?

Are we still talking alpha=Angle of Attack? Or is "alpha" different in the spacecraft usage?

Low Alpha is where planes (especially fast movers) prefer to live. High alpha is when bad things start to happen. . .

That's what I'm using alpha for. During the flight where SpaceShip One did all the vertical rolls it went to pretty much zero angle of attack. Bad things did happen at that point.

 

[PropAddict]

Yeah, I got it now. Thanks.

My point it Zero or even negative AoA is fine. Plenty of planes do it on a regular basis. The low AoA was just one contributor, not the causal factor. Bigger vertical tails would have eliminated the whole problem.

 

[yak52driver]

Yeah, I got it now. Thanks.

My point it Zero or even negative AoA is fine. Plenty of planes do it on a regular basis. The low AoA was just one contributor, not the causal factor. Bigger vertical tails would have eliminated the whole problem.

And it looks like they have put larger tail surfaces on SpaceShip Two, based on the few pictures available.