Space Ship Two - General Thread

[meekGee]

Veeery interesting. Is this an indication that the pace of XCOR is quickening?

Or of VG not quickening? Or possibly of normal career movement & turnover.

In the inter-dynamics of Mojave, this is significant.

Good for Greason.  I thought he had the right approach from the beginning, and also the right attitude.  Too bad he didn't have the resources, but slow and steady is going to win this one.

[a_langwich]

Brian Binnie is leaving Scaled for XCOR Aerospace:

http://www.spacenews.com/article/features/40089spaceship-pilot-joins-rival-firm

No raised eyebrows that a business manager and pilot at one company becomes chief engineer at the other?  Isn't Greason the chief engineer?  Or does XCOR have all chiefs?

[Rabidpanda]

No raised eyebrows that a business manager and pilot at one company becomes chief engineer at the other?  Isn't Greason the chief engineer?  Or does XCOR have all chiefs?

The Space News article now says 'senior engineer', not chief engineer.

[meekGee]

Brian Binnie is leaving Scaled for XCOR Aerospace:

http://www.spacenews.com/article/features/40089spaceship-pilot-joins-rival-firm

No raised eyebrows that a business manager and pilot at one company becomes chief engineer at the other?  Isn't Greason the chief engineer?  Or does XCOR have all chiefs?

No worries about XCor's focus.  They are a very technical group.  In an interesting parallel to SpaceX, they also started by making their own engine, and also had a market for engines before they started to attach them to airplanes.

[sdsds]

Branson claimed it was a conversation in 1988 with a young boy named Shihan Musafer on the BBC children’s show Going Live! that inspired him
http://www.telegraph.co.uk/travel/travelnews/10756181/Richard-Branson-launches-search-for-child-who-inspired-Virgin-Galactic.html

[parabolicarc]

Branson claimed it was a conversation in 1988 with a young boy named Shihan Musafer on the BBC children’s show Going Live! that inspired him
http://www.telegraph.co.uk/travel/travelnews/10756181/Richard-Branson-launches-search-for-child-who-inspired-Virgin-Galactic.html

A publicity move to distract attention away from the increasingly long gap in flight tests. SpaceShipTwo's last powered flight was three months ago today. It flew without engine power a week later, but nothing since.

SS2 is undergoing modifications to accommodate changes in the propulsion system.

Meanwhile, Sir Richard is 90 percent sure he and his kids will be flying to space in September.

http://fusion.net/News/video/richard-branson-space-travel-576438

For that to happen safely, they'd need to do a lot of flight testing over the next five months starting like now. If they do just a handful of flights then put Branson and kids aboard, that would be a profoundly bad idea. 

[Danderman]

SS2 is undergoing modifications to accommodate changes in the propulsion system.

Is that a rumor, informed speculation, or confirmed fact?

[Vultur]

For that to happen safely, they'd need to do a lot of flight testing over the next five months starting like now. If they do just a handful of flights then put Branson and kids aboard, that would be a profoundly bad idea.

Why?

I mean, I understand that it would be risky to get into a vehicle that's only been successfully powered-flight-tested three or four times, but it doesn't strike me as insane risky. I mean, there's a pilot in the vehicle even during the flight tests that have happened.

Unless there's something fundamentally wrong with the vehicle (not just underpowered, but likely to crash or explode) I'd say it's a risky idea, but maybe not "profoundly bad".

(I understand that there needs to be a test pilot, while Branson being there is an unnecessary risk from the perspective of the test itself... but from the perspective of the company/project as a whole I can see the advantage, demonstrating his confidence in his vehicle in a very public and direct way.)

I do think bringing the family along may be a bridge too far...  (These people are late 20s/early 30s though, it's not like he's bringing little kids along...)

EDIT: italics

[parabolicarc]

SS2 is undergoing modifications to accommodate changes in the propulsion system.

Is that a rumor, informed speculation, or confirmed fact?

Confirmed from multiple sources.

[parabolicarc]

For that to happen safely, they'd need to do a lot of flight testing over the next five months starting like now. If they do just a handful of flights then put Branson and kids aboard, that would be a profoundly bad idea.

Why?

I mean, I understand that it would be risky to get into a vehicle that's only been successfully powered-flight-tested three or four times, but it doesn't strike me as insane risky. I mean, there's a pilot in the vehicle even during the flight tests that have happened.

Unless there's something fundamentally wrong with the vehicle (not just underpowered, but likely to crash or explode) I'd say it's a risky idea, but maybe not "profoundly bad".

(I understand that there needs to be a test pilot, while Branson being there is an unnecessary risk from the perspective of the test itself... but from the perspective of the company/project as a whole I can see the advantage, demonstrating his confidence in his vehicle in a very public and direct way.)

I do think bringing the family along may be a bridge too far...  (These people are late 20s/early 30s though, it's not like he's bringing little kids along...)

EDIT: italics

Three or four flights before putting Branson aboard would be too short. It just pushes the flight envelope too fast. First, the ship's center of gravity is changed by the mods. That requires drop tests first, then powered flights going higher and faster. You don't want to rush that.

One of the problems is the cost of the hybrid engine, which is not reusable. The test flights are very expensive because of this factor. With XCOR, if they're not happy during the test flight program, they just go up and fly again. Costs are fuel and personnel. Virgin doesn't have that same capability. Or at least they can't do it cheaply.

I doubt Holly will go. Maybe Sam will. But, Richard Branson is used to taking risks in flight.

[yg1968]

Why are the hybrid engines not reusable? Will the new engine use different fuel?

[JBF]

Why are the hybrid engines not reusable? Will the new engine use different fuel?

They are reusable, but you have to remove them to refill and cure the solid propellent.

[Jarnis]

Why are the hybrid engines not reusable? Will the new engine use different fuel?

They are reusable, but you have to remove them to refill and cure the solid propellent.

Well, I would call them "refurbishable" rather than "reusable".

[parabolicarc]

Why are the hybrid engines not reusable? Will the new engine use different fuel?

The nitrous oxide tank can be refilled. But, the solid part of the motor is in a casing. The spent casing has to be removed and replaced with a new casing full of rubber. (They're also testing a nitrous oxide motor that burns nylon.)

[parabolicarc]

SpaceShipTwo hasn't flown in three months, and it might not resume flight tests for a couple of months at the earliest, but the marketing and optimistic predictions are continuing apace. Partnerships with Land Rover and a spaceflight offer from Virgin Australia:

http://www.parabolicarc.com/2014/04/14/virgin-galactic-forms-partnership-land-rover/

http://www.parabolicarc.com/2014/04/15/virgin-australia-offers-space-class-spaceshiptwo-flight/

http://fusion.net/News/video/richard-branson-space-travel-576438

And Branson has doubled down on his September flight plans, regardless of what's actually happening in Mojave:

http://fusion.net/News/video/richard-branson-space-travel-576438

[R7]

The spent casing has to be removed and replaced with a new casing full of rubber.

Can the casing do multiple flights refurbished or always brand new casing? The throat and nozzle are ablative, no?

[Zed_Noir]

The spent casing has to be removed and replaced with a new casing full of rubber.

Can the casing do multiple flights refurbished or always brand new casing? The throat and nozzle are ablative, no?

If the nozzle & throat are ablative it might be cheaper just to use all new components. You would have to to disassemble the expanded hybrid motors and remove all the residue anyway before putting in new rubber if reusing the casings again.

[Elmar Moelzer]

I never understood why they chose those hybrid engines. Kerosene engines seem to be much more useful.

[Lurker Steve]

The spent casing has to be removed and replaced with a new casing full of rubber.

Can the casing do multiple flights refurbished or always brand new casing? The throat and nozzle are ablative, no?

I assume the plan is just to remove the entire hybrid engine assembly, and replace it with another that is ready to go. The hybrid engines can be refurbished between flights separate from the SS2.

I also assume they plan on multiple SS2 vehicles if they need a more frequent flight rate. Any idea how long it takes to physically mate the SS2 to the WK2 carrier aircraft ?

[hop]

I never understood why they chose those hybrid engines. Kerosene engines seem to be much more useful.

If you were designing it now, I would agree, but it makes more sense in the context of when the decision was originally made. When SS1 was being designed, sufficiently high performance liquid engines were pretty much the domain of Big Aerospace. Developing one would be expected to be expensive and technically risky. Hybrids were supposed to be the cheap and simple alternative. When it came time to do SS2, a "simple" development from SS1 was still a logical choice, even if the engine choice was starting to looks sub-optimal.

Fast forward to today, hybrids turned out to be not so simple and other groups showed that it was possible to develop LOX/hydrocarbon engines on a relatively small budget.