Space Ship Two - General Thread

[FutureSpaceTourist]

Jeff Foust has a good piece about the fuel change and other work at VG (including the seats!):
http://www.newspacejournal.com/2014/05/24/virgin-galactic-changes-fuels-as-it-prepares-for-its-next-round-of-test-flights/

[Nomadd]

Great video!
Looks like the quality of the burn is slowly getting less stable and clear after a while, or is that just my personal impression?

Yes. The burn does not look very stable, the flame seems to "oscillate" a bit. But the combustion looks cleaner than the previous hybrid engine.

You wouldn't expect the plume to look the same at sea level as it will at working altitude.

 I actually considered signing up for one of these. The part where they only guaranteed 50 miles, which implied only two minutes of weightlessness was a killer for me. Getting "almost" to space and spending the time strapped in the seat wasn't worth two hundred grand.

[vt_hokie]

 I actually considered signing up for one of these. The part where they only guaranteed 50 miles, which implied only two minutes of weightlessness was a killer for me. Getting "almost" to space and spending the time strapped in the seat wasn't worth two hundred grand.

I'd settle for Mach 2 @ 60,000 ft.  I'm so angry with myself for not flying on the Concorde before that aircraft's premature retirement.  I guess in my youth I was naive enough to believe commercial aviation would continue advancing.  (And unlike VG, I could realistically have pulled off paying for a Concorde ticket before the aircraft's retirement in 2003....grr, kicking myself now!)

[andreto]

How about having something other than just a rumour, before people start telling VG what they do or don't need

[parabolicarc]

Great video!
Looks like the quality of the burn is slowly getting less stable and clear after a while, or is that just my personal impression?

If this is the same test that I saw, the engine behaved a bit oddly at the end. The best description I can think of is that it burped. The flame began to burn out and went down, then went up again briefly. That was followed by venting of white gas. This explains why the shutdown isn't shown on the video.

[Darkseraph]

Bizzare bait and switch. I think I'll settle for the vomit comet since its orders of magnitude cheaper.

[butters]

Doesn't look like stable thrust and exhaust velocity to me. I'd be impressed if some guys built this in a garage out of paintball gun parts and such. But a big name like Virgin, developing a human-rated rocket... doesn't inspire a lot of confidence.

When you see the Grasshopper/F9R-dev1 flights, it's clear that SpaceX has a very good understanding of the M1D and can exercise very precise control over its operation. This nitrous-nylon hybrid looks like they just got it to kinda sorta work mostly.

[Lars_J]

Great video!
Looks like the quality of the burn is slowly getting less stable and clear after a while, or is that just my personal impression?

Yes. The burn does not look very stable, the flame seems to "oscillate" a bit. But the combustion looks cleaner than the previous hybrid engine.

You wouldn't expect the plume to look the same at sea level as it will at working altitude.

The altitude has nothing to do with the stability (or lack thereof) of the flame.

[FutureSpaceTourist]

If this is the same test that I saw, the engine behaved a bit oddly at the end. The best description I can think of is that it burped. The flame began to burn out and went down, then went up again briefly. That was followed by venting of white gas. This explains why the shutdown isn't shown on the video.

Thanks for the explanation. Sigh, with VG things are never quite as they portray them. I wish they'd learn that in the long run endless spin does more harm than good. I really hope they are more forthcoming with their customers, but I fear not.

Having said that the previous rubber hybrid was hardly smooth at burnout either. Does it matter? For example, wouldn't any vibration effects be less than when the rocket is running at full power?

[banjo]

 I actually considered signing up for one of these. The part where they only guaranteed 50 miles, which implied only two minutes of weightlessness was a killer for me. Getting "almost" to space and spending the time strapped in the seat wasn't worth two hundred grand.

I'd settle for Mach 2 @ 60,000 ft.  I'm so angry with myself for not flying on the Concorde before that aircraft's premature retirement.  I guess in my youth I was naive enough to believe commercial aviation would continue advancing.  (And unlike VG, I could realistically have pulled off paying for a Concorde ticket before the aircraft's retirement in 2003....grr, kicking myself now!)

sorry OT.  everything about concorde's retirement makes me angry. 

[Darkseraph]

 I actually considered signing up for one of these. The part where they only guaranteed 50 miles, which implied only two minutes of weightlessness was a killer for me. Getting "almost" to space and spending the time strapped in the seat wasn't worth two hundred grand.

I'd settle for Mach 2 @ 60,000 ft.  I'm so angry with myself for not flying on the Concorde before that aircraft's premature retirement.  I guess in my youth I was naive enough to believe commercial aviation would continue advancing.  (And unlike VG, I could realistically have pulled off paying for a Concorde ticket before the aircraft's retirement in 2003....grr, kicking myself now!)

sorry OT.  everything about concorde's retirement makes me angry.

I can't imagine why. Halving your flight time by paying 10 times the cost is not a reasonable trade in the era of internet on the plane itself. Its cool and all but the most annoying thing about flying is the time in the airport on both sides, not the actual flight. I know Off Topic!!

[docmordrid]

Longish Aviation Week article covers the WK2 spar issue ("extra adhesive"), the new fuel grain (developed by Scaled) and the tests before first flight of the new grain.  Expecting 110km from the new grain.

http://m.aviationweek.com/space/new-fuel-boost-spaceship-two

[Lar]

Yes, Concorde is off topic. Some other mod might still delete those posts but no more please.

[meadows.st]

Virgin Galactic Hybrid Rocket Motor Test - May 8 2014

Published on May 23, 2014
Footage from Virgin Galactic's recent Hybrid Rocket Motor Test

Wow! Serious instability at 20 seconds then again between 26-27 seconds and all shock diamonds are gone by 40 seconds.

[Lar]

Wow! Serious instability at 20 seconds then again between 26-27 seconds and all shock diamonds are gone by 40 seconds.

For those of us that may not be up on flow dynamics of rocket exhaust, are shock diamonds a good thing? At least for this fuel combination? What sorts of engines are they a good (or at least acceptable) sign?

https://en.wikipedia.org/wiki/Shock_diamond says they are unburnt fuel and a sign of either over or under expansion. No way a non variable nozzle can be correctly expanded at all altitudes so? normal?? Is it worth running non fuel-rich to avoid them?

[savuporo]

Virgin Galactic is good at PR.

Depends on your point of view. IMO "good PR" is PR approach that does not raise any controversy at all and is fully truthful and open. There are few companies that pull this off, VG is not one of them.

I'd also note that Doug has been on this story for a long time,...

And he hits with another one :
http://www.parabolicarc.com/2014/05/26/virgin-galactic-3/

[dcporter]

Virgin Galactic is good at PR.

IMO "good PR" is PR approach that does not raise any controversy at all and is fully truthful and open.

That seems... optimistic.

[mr. mark]

Doug has always been truthful and pretty much right on. As far as his ongoing conversations with Virgin Galactic, He should let it go. Keep reporting the truth and eventually Virgin Galactic will get with the program as it seems to be with the recent motor change. That's a positive. Nothing can come of constant bantering back and forth. In the end it's not about who's right for ego's sake. It's only about reporting accurately whether they're your buddies or not.

[parabolicarc]

Doug has always been truthful and pretty much right on. As far as his ongoing conversations with Virgin Galactic, He should let it go. Keep reporting the truth and eventually Virgin Galactic will get with the program as it seems to be with the recent motor change. That's a positive. Nothing can come of constant bantering back and forth. In the end it's not about who's right for ego's sake. It's only about reporting accurately whether they're your buddies or not.

Thanks Mr. Mark. Appreciate your praise of my work.

I'll let the piece stand on its own merits. The only thing I would add is this is not about ego -- proving who's right. I can deal with being wrong. And I generally don't like making things personal and getting into pissing matches with others. I'd rather win people over with a good argument than to call them idiots. At the least we can agree to disagree with mutual respect.

But, it was necessary to stand up to these attacks on my reporting and my character. If I didn't, it would just continue unabated. I also felt what they were telling their customers was just plain wrong. Some of them are friends of mine. 

I don't know how they will respond, if they do. I want to move on and report on the engine change, which could turn out to be quite an interesting story. Stay tuned. There could be some interesting revelations coming out of that.

[baldusi]

For what its worth, I have nothing but absolute respect for your reporting integrity. You've demonstrated that you were right, and all that storm only makes your work the more trustable. You've clearly came out stronger out of this, i just wish they would accept that denying problems until they hit you in the face only makes you lose your credibility. Let's supposed now that their nylon engine actually is a superior solution. I won't believe them because of past behavior.