Virgin Galactic and SpaceShipTwo Master Thread (1)

[docmordrid]

Lets not forget that XCOR is using their new cryo piston pumps, and supposedly working with ULA on adapting it and other bits to upper stages. If it's as cheap as they claim....

XCOR....

[HMXHMX]

Lets not forget that XCOR is using their new cryo piston pumps, and supposedly working with ULA on adapting it and other bits to upper stages. If it's as cheap as they claim....

XCOR....

The problem for VG following such a path and buying XCOR components would be like Boeing buying P&W engines when P&W was building their own aircraft for sale.

[Robotbeat]

Lets not forget that XCOR is using their new cryo piston pumps, and supposedly working with ULA on adapting it and other bits to upper stages. If it's as cheap as they claim....

XCOR....

The problem for VG following such a path and buying XCOR components would be like Boeing buying P&W engines when P&W was building their own aircraft for sale.

Well... the manufacturer of VG's rocket motor (Sierra Nevada) is also building DreamChaser, which is (was?) purported to be used for suborbital tourism flights, as well.

Virgin Galactic wants to be primarily an operator, while XCOR wants to be primarily a spacecraft builder. There may be room for cooperation in the future.

[HMXHMX]

Lets not forget that XCOR is using their new cryo piston pumps, and supposedly working with ULA on adapting it and other bits to upper stages. If it's as cheap as they claim....

XCOR....

The problem for VG following such a path and buying XCOR components would be like Boeing buying P&W engines when P&W was building their own aircraft for sale.

Well... the manufacturer of VG's rocket motor (Sierra Nevada) is also building DreamChaser, which is (was?) purported to be used for suborbital tourism flights, as well.

Virgin Galactic wants to be primarily an operator, while XCOR wants to be primarily a spacecraft builder. There may be room for cooperation in the future.

The "DC as suborbital" idea was Jim Benson's and died with him.  SNC has no plans to go suborbital with DC.

[Garrett]

VG doesn't have an engine issue.  They have a propulsion system problem.  I once created a paraphrase of the old military truism: "Amateurs argue about tactics; professionals talk about logistics."  My paraphrase replaces "tactics" with "engines" and "logistics" with "pressurization systems."  (No offense meant to amateurs, truly....)

Pressurization costs about $2 for every $1 spent on the engine (I've found the hard way).  For SS2, there are additional considerations that generally aren't as significant or even applicable for a conventional rocket, such as Cg, ride comfort, human safety and turn time.

This observation applies to a pressure-fed option, rather than a pump-fed one, but I'd bet long odds that the pump will cost you more than the ratio in the above example. 

VG could adopt an existing pump fed engine if there was one available in the right thrust class (there is, but I'm not saying) or they can start over from scratch and buy/build a new system. 

Quite a lot to digest in your post. And yes, I'm extremely offended! And I'm not even an amateur - I'm several grades below amateur status 

You say they have a propulsion system problem almost as if it's a certainty. So far we were only talking about a wild rumor. Have you some other info you'd like to share?

When you say that "Pressurization costs about $2 for every $1 spent on the engine", do you mean that once the engine is built, it can cost twice as much just to fill her up, so to speak?

[Cinder]

It sounds like he means development-wise.

[Rocket Science]

HMX offers sage advice... I'd listen to it...

[HMXHMX]

VG doesn't have an engine issue.  They have a propulsion system problem.  I once created a paraphrase of the old military truism: "Amateurs argue about tactics; professionals talk about logistics."  My paraphrase replaces "tactics" with "engines" and "logistics" with "pressurization systems."  (No offense meant to amateurs, truly....)

Pressurization costs about $2 for every $1 spent on the engine (I've found the hard way).  For SS2, there are additional considerations that generally aren't as significant or even applicable for a conventional rocket, such as Cg, ride comfort, human safety and turn time.

This observation applies to a pressure-fed option, rather than a pump-fed one, but I'd bet long odds that the pump will cost you more than the ratio in the above example. 

VG could adopt an existing pump fed engine if there was one available in the right thrust class (there is, but I'm not saying) or they can start over from scratch and buy/build a new system. 

Quite a lot to digest in your post. And yes, I'm extremely offended! And I'm not even an amateur - I'm several grades below amateur status 

You say they have a propulsion system problem almost as if it's a certainty. So far we were only talking about a wild rumor. Have you some other info you'd like to share?

When you say that "Pressurization costs about $2 for every $1 spent on the engine", do you mean that once the engine is built, it can cost twice as much just to fill her up, so to speak?

I'm not privy to any information about VG's current propulsion system that isn't public.  But it doesn't take 6 or 7 years to develop this class of system (2-3 should be sufficient) and it is obvious there are problems from the very few firings performed, the very long time between firings, and the fairly obvious mod to SS2 discussed earlier.

I also have the long held opinion, that I shared with the in 2004, that a hybrid is not suitable for a commercial vehicle operating at the flight rate they intend.

Regarding the 2:1 ratio, I was referring to development.

[Jason1701]

What was the fairly obvious mod?

[HMXHMX]

What was the fairly obvious mod?

The hump.

[Robotbeat]

VG doesn't have an engine issue.  They have a propulsion system problem.  I once created a paraphrase of the old military truism: "Amateurs argue about tactics; professionals talk about logistics."  My paraphrase replaces "tactics" with "engines" and "logistics" with "pressurization systems."  (No offense meant to amateurs, truly....)

Pressurization costs about $2 for every $1 spent on the engine (I've found the hard way).  For SS2, there are additional considerations that generally aren't as significant or even applicable for a conventional rocket, such as Cg, ride comfort, human safety and turn time.

This observation applies to a pressure-fed option, rather than a pump-fed one, but I'd bet long odds that the pump will cost you more than the ratio in the above example. 

VG could adopt an existing pump fed engine if there was one available in the right thrust class (there is, but I'm not saying) or they can start over from scratch and buy/build a new system. 

Yeah, as I've found by just trying to build a simple rocket igniter... A rocket is (or seems like it is) mostly plumbing. The thrust chamber itself is practically a sidenote, or at least that's how it feels!

[Garrett]

Regarding the 2:1 ratio, I was referring to development.

OK, it just sounded strange from a not-even-an-amateur viewpoint. I would have thought that pressurization would be included in the cost of engine development, so I would have put it more like this: for every $3 spent on developing an engine, $2 goes to pressurization issues.

Does that make sense?  Though I think I'm beginning to realize why you said it the other way around.

[HMXHMX]

Regarding the 2:1 ratio, I was referring to development.

OK, it just sounded strange from a not-even-an-amateur viewpoint. I would have thought that pressurization would be included in the cost of engine development, so I would have put it more like this: for every $3 spent on developing an engine, $2 goes to pressurization issues.

Does that make sense?  Though I think I'm beginning to realize why you said it the other way around.

No particular reason.  People frequently speak about engines and pressurizations separately.  Let's agree that the point I was making if that pressurization can cost two thirds of the propulsion system development. 

[baldusi]

Excuse my ignorance, but when you say pressurization you mean the turbopump, one way valves and pressure regulators? Or you add all the plumbing from each tank? Do you also add the repressurization system for tanks, too? And the start up pressure (via hypergolic, pyros, hellium or whatever)? Do you also mean the pressure drops an plumbing for a regeneratively cooled chamber?

[HMXHMX]

Excuse my ignorance, but when you say pressurization you mean the turbopump, one way valves and pressure regulators? Or you add all the plumbing from each tank? Do you also add the repressurization system for tanks, too? And the start up pressure (via hypergolic, pyros, hellium or whatever)? Do you also mean the pressure drops an plumbing for a regeneratively cooled chamber?

For pressure-fed systems, the pressurization subsystem includes the propellant tank(s), all plumbing and valving up to the engine interface, the pressurant gas(es) and their storage vessels, regulators, heat exchanger if required, control computer and sensors, and the overall thermochemical and thermodynamic behavior of the integrated system.

Pump-fed systems will also have a pressurization subsystem, to maintain Net Positive Suction Head (NPSH) inlet pressures to the turbo-machinery, but these are generally less complicated to design than propulsion system that rely upon tank pressure to supply the engine chamber pressure.

[Robotbeat]

Excuse my ignorance, but when you say pressurization you mean the turbopump, one way valves and pressure regulators? Or you add all the plumbing from each tank? Do you also add the repressurization system for tanks, too? And the start up pressure (via hypergolic, pyros, hellium or whatever)? Do you also mean the pressure drops an plumbing for a regeneratively cooled chamber?

For pressure-fed systems, the pressurization subsystem includes the propellant tank(s), all plumbing and valving up to the engine interface, the pressurant gas(es) and their storage vessels, regulators, heat exchanger if required, control computer and sensors, and the overall thermochemical and thermodynamic behavior of the integrated system.

Pump-fed systems will also have a pressurization subsystem, to maintain Net Positive Suction Head (NPSH) inlet pressures to the turbo-machinery, but these are generally less complicated to design than propulsion system that rely upon tank pressure to supply the engine chamber pressure.

Blowdown, baby!

[HMXHMX]

Excuse my ignorance, but when you say pressurization you mean the turbopump, one way valves and pressure regulators? Or you add all the plumbing from each tank? Do you also add the repressurization system for tanks, too? And the start up pressure (via hypergolic, pyros, hellium or whatever)? Do you also mean the pressure drops an plumbing for a regeneratively cooled chamber?

For pressure-fed systems, the pressurization subsystem includes the propellant tank(s), all plumbing and valving up to the engine interface, the pressurant gas(es) and their storage vessels, regulators, heat exchanger if required, control computer and sensors, and the overall thermochemical and thermodynamic behavior of the integrated system.

Pump-fed systems will also have a pressurization subsystem, to maintain Net Positive Suction Head (NPSH) inlet pressures to the turbo-machinery, but these are generally less complicated to design than propulsion system that rely upon tank pressure to supply the engine chamber pressure.

Blowdown, baby!

Indeed.  That's how SSO operated and how SS2 was originally designed to operate, prior to the apparent addition of helium pressurization.

[HMXHMX]

For those of you who may be going to the AIAA JPC next week in San Diego, the Commercial Space Group of AIAA sent out this invitation:

"If you’ll be attending the Joint Propulsion Conference in San Diego next week, you are cordially invited to join with AIAA’s Commercial Space Group for an informal briefing from Frank Taylor, Chief Engineer for Dream Chaser and Space Exploration Systems at Sierra Nevada.  Refreshments will be served and an informal discussion with Frank will follow.  San Diego Convention Center, Room 23B,  6:00 PM, Monday, August 1."

The Group meetings are always quite informative. 

Cross posted to both VG and DC threads.

[baldusi]

Excuse my ignorance, but when you say pressurization you mean the turbopump, one way valves and pressure regulators? Or you add all the plumbing from each tank? Do you also add the repressurization system for tanks, too? And the start up pressure (via hypergolic, pyros, hellium or whatever)? Do you also mean the pressure drops an plumbing for a regeneratively cooled chamber?

For pressure-fed systems, the pressurization subsystem includes the propellant tank(s), all plumbing and valving up to the engine interface, the pressurant gas(es) and their storage vessels, regulators, heat exchanger if required, control computer and sensors, and the overall thermochemical and thermodynamic behavior of the integrated system.

Pump-fed systems will also have a pressurization subsystem, to maintain Net Positive Suction Head (NPSH) inlet pressures to the turbo-machinery, but these are generally less complicated to design than propulsion system that rely upon tank pressure to supply the engine chamber pressure.

From this I have to understand that a pressure-fed system is a bit more complicated than one feeding a pumped system?

[docmordrid]

http://www.parabolicarc.com/2011/07/29/george-whitesides-virgin-galactic-making-good-progress/

George Whitesides: Virgin Galactic Making Good Progress
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The Elephant (in the Room)

SpaceShipTwo engine: It’s hard. Sierra Nevada (prime contractor) has had a scaleup hybrid engine.

Good progress over the summer.

We expect it will be flying in space next year

Referred to video that SNC’s Mark Sirangelo showed yesterday (which  believe was a smaller version for designed for on-orbit maneuvering by Dream Chaser shuttle)
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