Updates SpaceShipTwo to begin powered flights by end of year!

[Andy44]

I just noticed how when the feather is deployed the shape of the vehicle as seen from the bottom looks like the STS shuttle wing shape.

 

[orb]

Discovery News: SpaceShipTwo Trial Run Scrubbed

 

[RGClark]

Virgin Galactic Now Aiming for Spaceflight in February.
Posted by Doug Messier on September 27, 2013, at 10:35 pm in News

...The problem is that despite public claims to the contrary, the nitrous oxide-rubber hybrid has never been hot fired on the ground at full duration, sources indicate. And the engine is not powerful enough even when fully fired to get SpaceShipTwo into space with any actual payloads (i.e., six wealthy passengers).
Even as Scaled Composites has pursued the flight test program and Virgin Galactic has issued optimistic flight predictions that commercial flights are only months away, the two companies have been secretly working on alternatives to the nitrous oxide-rubber engine they have been using to explore SpaceShipTwo’s flight envelope.
Sources report that the development of alternative hybrid designs has been running into trouble. An engine that used nitrous oxide and nylon exploded on Scaled Composites test stand on May 17. The nozzle and rocket casing were thrown clear and the test stand was wrecked. The composite tank holding the nitrous oxide did not explode, but it was damaged to the point where it could not be reused.
Scaled said they were testing an experimental, non-flight engine into which they had introduced flaws on that day. Sources say this is true; however, the explosion and wrecked test stand were not part of the test plan.
There has been work done on developing a liquid-fuel engine, which many experts see as a better long-term solution. A hybrid engine must be replaced after each flight, a process that is a delicate, complicated and expensive. A robust, reusable liquid engine would allow SpaceShipTwo to be refueled and fly again the same day.
It is not clear whether a liquid-fuel replacement is in active development at the moment, or how long it might take to get one ready for flight test on a SpaceShipTwo vehicle.
http://www.parabolicarc.com/2013/09/27/virgin-galactic-aiming-spaceflight-february/

In point of fact studies have shown that ShipShipTwo if switched to liquid-hydrogen fueled could on its own reach suborbital space without the need for a carrier aircraft. Moreover the engine needed is already existing in the engine for the cryogenic upper stage of the Ariane 5, though you may need two of them. This liquid fueled engine would also be reusable at least up to ten flights unlike the hybrid which needs to be replaced each flight.
Not having to use the carrier aircraft WhiteKnightTwo would make both development cost and flight costs cheaper. And not having to spend money on developing a new engine would be also a big cut in the development cost. Being reusable the liquid fueled engine would probably be cheaper per use than the hybrid also.
Keep in mind also that reusable liquid fueled engines were used from the very earliest times of rocket powered human flight in the X-15. This cut drastically the costs per flight.

c.f.,
SpaceShipTwo could be single stage to suborbit says ESA firm.
By Rob Coppinger on April 29, 2010 4:24 PM
http://www.flightglobal.com/blogs/hyperbola/2010/04/spaceshiptwo_could_be_single_s/

Reusable Space Plane Idea Intrigues Europeans.
Rob Coppinger, SPACE.com Contributor
Date: 01 May 2012 Time: 04:30 PM ET
http://www.space.com/15494-vinci-space-plane-suborbital-flight-idea.html

Bob Clark

 

[MaverickSawyer]

I know Aerojet was offering a LOX/hydrocarbon engine of some sort for SS2. However, they opted for the hybrid for the time being because of simplicity.
As for an LH2 powered stage: :shifty: I'd prefer LOX/CH4, but there's none on the market. LOX/RP1 would probably be a good bet.

 

[RGClark]

I know Aerojet was offering a LOX/hydrocarbon engine of some sort for SS2. However, they opted for the hybrid for the time being because of simplicity.
As for an LH2 powered stage: :shifty: I'd prefer LOX/CH4, but there's none on the market. LOX/RP1 would probably be a good bet.

Given that XCOR believes the Lynx can be suborbital as kerosene fueled, it's probably true also for SS2. There is the question of the engine. Possibly the Merlin 1D could be used. But it would be rather overpowered at 160,000 lbs vacuum thrust.
Another might be the SpaceX Kestrel. But you would probably need 4 or 5 of those.

Bob Clark

 

[MaverickSawyer]

I think it was custom design, not OTS. Probably had comparable thrust to the hybrid installed now.

 

[RGClark]

Recent reports are that the hybrid engine on SpaceShipTwo still might not have enough thrust to get it to suborbital flight after ten years of development. However, by switching SpaceShipTwo to liquid fuel not only would it have a faster route to first suborbital flight, but it could serve as a prototype of a reusable first stage of a two-stage orbital system:

Transitioning SpaceShipTwo to liquid fueled engines: a technology driver to reusable orbital launchers.
http://exoscientist.blogspot.com/2014/01/transitioning-spaceshiptwo-to-liquid.html.

Bob Clark

 

[Hlynkacg]

It would also necessitate a major redesign of the spacecraft.

 

[Urwumpe]

It would also necessitate a major redesign of the spacecraft.

Exactly. Also, the post is another spam of him pointing to his own blog and no news or at least anywhere based on facts. His blog points to a rubbish book about Richard Branson, written by some guy who appears to be just another boulevard journalist. Thats where it all begins and ends.

http://www.parabolicarc.com/2014/01/22/scaled-updates-rm2-hot-fire-logs-boy-useless/

This is the only interesting thing there - but it means little. The lack of information can also be related to business secrets, remember, this is not the public NASA development.

That hybrid engines are pretty unknown for larger scales is no secret (do you know any example larger than RocketMotorOne?)... but the power density of a bipropellant rocket would be much lower and thus, have even LESS impulse available to reach suborbital flight for the given size of the spacecraft.

Any change in propulsion would mean a full redesign of everything. Including White Knight 2.

 

[C3PO]

Transitioning SpaceShipTwo to liquid fueled engines: a technology driver to reusable orbital launchers.

There is no evidence for any plans of a liquid fueled SS2. And I fail to see the link between SS2 and an orbital launcher.

 

[PhantomCruiser]

The only commonality that I can think of between the two are the air-dropped SS2 via WK2 and the air-dropped Pegasus via L1011?

 

[C3PO]

SS2 isn't orbital, and Pegasus isn't reusable.

 

[PhantomCruiser]

Hey we keep this up and we can have some logical fallacies of our own. :yes:

 

[RGClark]

Exactly. Also, the post is another spam of him pointing to his own blog and no news or at least anywhere based on facts. His blog points to a rubbish book about Richard Branson, written by some guy who appears to be just another boulevard journalist. Thats where it all begins and ends.
http://www.parabolicarc.com/2014/01/22/scaled-updates-rm2-hot-fire-logs-boy-useless/
This is the only interesting thing there - but it means little. The lack of information can also be related to business secrets, remember, this is not the public NASA development.
That hybrid engines are pretty unknown for larger scales is no secret (do you know any example larger than RocketMotorOne?)... but the power density of a bipropellant rocket would be much lower and thus, have even LESS impulse available to reach suborbital flight for the given size of the spacecraft.
Any change in propulsion would mean a full redesign of everything. Including White Knight 2.

It's a matter of who you consider to be a reliable source on the development of the SS2. Not just this author of the book on Branson but the author of that parabolicarc.com site have noted that the discussion at Mojave is that the original hybrid engine is underpowered to reach suborbital flight. The blog author Doug Messier is a respected reporter on space issues.
This is one reason why VG is considering changing the fuel to nylon. Another is the large amount of vibration that has been found with the larger version of the hybrid engine, compared to that on SS1. Certainly at this late date, after the development on the engine has been ongoing ten years, when the claim is SS2 would be making suborbital flights this year, that they are considering changing the fuel must give one pause.
High executives at VG have acknowledged that they may consider changing SS2 to liquid fueled at a later date. The fact that liquid fueled engines give higher performance than hybrids is well known. That is why the two independent studies I cited concluded SS2 could be suborbital without even needing WK2 when switched to hydrolox and why XCOR's Lynx can be suborbital using kerolox without needing a carrier aircraft.


Bob Clark

---------- Post added at 01:32 AM ---------- Previous post was at 12:43 AM ----------

There is no evidence for any plans of a liquid fueled SS2. And I fail to see the link between SS2 and an orbital launcher.

Any suborbital craft can serve as a lower stage to an orbital launch system. For instance XCOR is considering it for Lynx:

XCOR Aerospace Makes Plans for Reusable Orbital Vehicle.
By Jeff Foust | Apr. 19, 2013

http://www.spacenews.com/article/la...pace-makes-plans-for-reusable-orbital-vehicle

Using higher performance liquid fueled engines on SS2 would allow it to reach higher delta-v thus have higher performance as a first stage of a orbital system.


Bob Clark

 

[Urwumpe]

Not just this author of the book on Branson but the author of that parabolicarc.com site have noted that the discussion at Mohave is that the original hybrid engine is underpowered to reach suborbital flight. The blog author Doug Messier is a respected reporter on space issues.

The problem is, that you have the criminal quoting habit to put words into the mouth of the people you quote, that have never said it in the source you link. As if you just read every third line, shout out in enthusiasm and post the link, saying "They are building reusable liquid engines, they are building SSTOs".

And contrary to you, I don't give a damn about "respected reporters". Either they make a good job in their articles, or they don't do it. If they have written a good article some years ago and the new one is a piece of crap to fill the pages.... does being a respected reporter make the article any better? Never judge a book by the cover.

Also: Nameless "high executives" can be replaced by "Uncle Bob" without reducing the accuracy of the statement. Anonymous sources are a very poor source except for rumors, which may or may not be unfounded.

PS: XCOR should finish their suborbital vessel first, before thinking about orbital... how many dozen flights have they already sold for the suborbital one without a single flight test?

 

[C3PO]

Any suborbital craft can serve as a lower stage to an orbital launch system. For instance XCOR is considering it for Lynx:

No! You need some payload capacity for that. :facts:

The fact that a different company plans to use liquid engine for a different craft designed for a different mission, is not evidence that Scaled are considering switching to liquid fuel.

 

[PhantomCruiser]

Whether of not the people over at XCOR can get some cubesats into LEO is currently irrelevant. Has their Lynx flown yet?

Once (if?) it takes to the skies, then maybe they can talk about it's potential. But right now it's a really nice static display.
That's not to say that they won't be capable, but at this time they've got no hardware into the sky.

 

[RGClark]

The problem is, that you have the criminal quoting habit to put words into the mouth of the people you quote, that have never said it in the source you link. As if you just read every third line, shout out in enthusiasm and post the link, saying "They are building reusable liquid engines, they are building SSTOs".

Pot meet kettle. Both in the post to this forum and in the blog post itself it quite specifically says two stage to orbit systems. This is important in itself when the first stage is reusable since the first stage is usually much larger than the upper stage and much more expensive. Then if you can at least make the first stage reusable you can cut significantly into your launch costs.

BTW, this might be especially important in regards to Falcon 1 and 1e, if SpaceX ever decided to restart them. Musk has said the cost of the Falcon 9 upper stage is about a quarter the cost of the full rocket, roughly mirroring the size of the stage. But for the F1 and F1e the upper stage is only about 1/10th the size of the full rocket. Judging on size basis we might estimate its cost as only 1/10th that of the full rocket, so in the range of $1,000,000 to $1,300,000. Note that since the upper stage just uses the much simpler, much smaller, pressure-fed Kestrel engine it might even cost less than that.
But if the lower stage being made reusable can cut its costs by a factor of 10, it would be in a similar cost range as just this small upper stage. So perhaps it would be only a couple of million dollars total per launch of this orbital rocket.
The payload would be reduced by making the first stage reusable but the price per kilo could be in the range of $1,000 per pound.


Bob Clark

 

[MaverickSawyer]

The fact that a different company plans to use liquid engine for a different craft designed for a different mission, is not evidence that Scaled are considering switching to liquid fuel.

Oh, but they DID consider it in the design phase: They approached Aerojet Sacramento about it briefly, then opted not to use liquids for simplicity and maintenance reasons.

 

[C3PO]

Oh, but they DID consider it in the design phase: They approached Aerojet Sacramento about it briefly, then opted not to use liquids for simplicity and maintenance reasons.

And why is that piece of info relevant? What do you think the purpose of a design phase is? I'm sure they considered everything but catapulting Kerbals out the back.
Switching to liquid fuel at this stage would most likely involve a complete redesign of the prototype.