Space Ship Two - General Thread

[baldusi]

NewtonOne is a pressure fed 15.6kN and NewtonTwo is also pressure fed but with 212kN. What could be the isp?
They would need a NewtonThree with ~270kN for the SpaceShipTwo?

[Lars_J]

NewtonOne is a pressure fed 15.6kN and NewtonTwo is also pressure fed but with 212kN. What could be the isp?
They would need a NewtonThree with ~270kN for the SpaceShipTwo?

Beating a hybrid rocket Isp should not be too difficult. And 270Kn seems to be within a reasonable evolution range of the NewtonTwo engine. (Merlin 1C to Merlin 1D was a bigger step)

My predition: within 6 months we will get a press release stating that SS2 will now be powered by their LauncherOne engine.

[FutureSpaceTourist]

For me the interesting question is why are VG releasing PR about this now? E.g.

1. Trying to drum up more LauncherOne customers
2. To distract from slow progress on SS2
3. They're confident about SS2 after recent flights, so now happy to discuss what comes next

BTW there's a nice article with bit more info at http://t.nbcnews.com/science/hello-newton-virgin-galactic-unveils-its-other-rocket-engine-2D11922691.

VG once again deny any plans to put the Newton engines into SS2.

P.S. Not sure why LauncherOne PR is on the SS2 thread; do you know something about this we we don't Chris?!

[Kabloona]

NewtonOne is a pressure fed 15.6kN and NewtonTwo is also pressure fed but with 212kN. What could be the isp?
They would need a NewtonThree with ~270kN for the SpaceShipTwo?

Beating a hybrid rocket Isp should not be too difficult. And 270Kn seems to be within a reasonable evolution range of the NewtonTwo engine. (Merlin 1C to Merlin 1D was a bigger step)

My predition: within 6 months we will get a press release stating that SS2 will now be powered by their LauncherOne engine.

Lars, wouldn't that require a major redesign of the vehicle to accommodate a completely different engine, tanks, engine control systems, etc? I can't see that happening because it would be such a huge schedule hit.

It sounds like they're hoping the nylon hybrid will save their bacon. That's more of a plug-and-play solution.

[Lars_J]

NewtonOne is a pressure fed 15.6kN and NewtonTwo is also pressure fed but with 212kN. What could be the isp?
They would need a NewtonThree with ~270kN for the SpaceShipTwo?

Beating a hybrid rocket Isp should not be too difficult. And 270Kn seems to be within a reasonable evolution range of the NewtonTwo engine. (Merlin 1C to Merlin 1D was a bigger step)

My predition: within 6 months we will get a press release stating that SS2 will now be powered by their LauncherOne engine.

Lars, wouldn't that require a major redesign of the vehicle to accommodate a completely different engine, tanks, engine control systems, etc? I can't see that happening because it would be such a huge schedule hit.

Yes, it will be a challenge, but one that I think they'll probably *must* undertake if they have any hope of flying several times per day. Rapid turnaround is essential and is not hybrid friendly.

Keep in mind that they already have an liquid oxidizer tank as part of the system. And the SS2 engine is a pressure-fed KeroLox engine - less complex on the liquid complexity scale.

It sounds like they're hoping the nylon hybrid will save their bacon. That's more of a plug-and-play solution.

How is it more plug-and-play?

[Kabloona]

It sounds like they're hoping the nylon hybrid will save their bacon. That's more of a plug-and-play solution.

How is it more plug-and-play?

Because it doesn't change the form factor of the existing motor, or any of the plumbing, tankage, or engine control systems. It's just a different solid material inside the same motor case.

[Lars_J]

It sounds like they're hoping the nylon hybrid will save their bacon. That's more of a plug-and-play solution.

How is it more plug-and-play?

Because it doesn't change the form factor of the existing motor, or any of the plumbing, tankage, or engine control systems. It's just a different solid material inside the same motor case.

Ah, I thought you meant that it would allow quicker turnaround of SS2 by allowing the hybrid engine to be switched out easier. My mistake.

[Borklund]

It sounds like they're hoping the nylon hybrid will save their bacon. That's more of a plug-and-play solution.

How is it more plug-and-play?

Because it doesn't change the form factor of the existing motor, or any of the plumbing, tankage, or engine control systems. It's just a different solid material inside the same motor case.

Ah, I thought you meant that it would allow quicker turnaround of SS2 by allowing the hybrid engine to be switched out easier. My mistake.

On the subject of switching out engines; have they mentioned turnaround speed at all?

[docmordrid]

Besides NewtonOne/Two NBC Cosmic Log also reported,

Ringuette said components for an upgraded NewtonThree engine are already undergoing testing.

and SS3/SS4. SS4 may be rhetorical, but ISTM NewtonThree could only be for SS2 or SS3.

[Robotbeat]

Yeah, as I keep saying, the inevitable switch to full liquid rockets is inevitable.

The sooner they get it done, the better!

[Lurker Steve]

Yeah, as I keep saying, the inevitable switch to full liquid rockets is inevitable.

The sooner they get it done, the better!

Actually, the sooner they start passenger flights the better. If they aren't lying and they can really get past 100kM with the hybrid engine in the SS2 this year, it would be great. Then Branson won't go broke before developing the SS3 that has a similar profile, but gets farther into space, or at least allows for longer suborbital flights.

With the SS2 only pushing 2.5 Gs for the ascent burn with the current hybrids, that's not too bad for their passenger list.

[parabolicarc]

Last time I checked SS2 has had 3 in flight motor burns and they seemed to go just fine. As far as some people not thinking that they like the engine or don't find the engine test results transparent well... that's their beef.

If the engine they're flying with could get them where they needed to go, why are there multiple alternatives under development at the current time? Including a nylon-nitrous engine tested last week?

Answer: it can't. And that's why other engines are being tested.

[Nomadd]

Last time I checked SS2 has had 3 in flight motor burns and they seemed to go just fine. As far as some people not thinking that they like the engine or don't find the engine test results transparent well... that's their beef.

If the engine they're flying with could get them where they needed to go, why are there multiple alternatives under development at the current time? Including a nylon-nitrous engine tested last week?

Answer: it can't. And that's why other engines are being tested.

We heard you the first 500 times.

[Lars_J]

Last time I checked SS2 has had 3 in flight motor burns and they seemed to go just fine. As far as some people not thinking that they like the engine or don't find the engine test results transparent well... that's their beef.

If the engine they're flying with could get them where they needed to go, why are there multiple alternatives under development at the current time? Including a nylon-nitrous engine tested last week?

Answer: it can't. And that's why other engines are being tested.

We heard you the first 500 times.

Apparently mr. mark didn't. But to add to what parabolicarc is saying, I don't necessarily think that developing alternatives is a sure sign of trouble. But that, taken together with the lengthy delays between test flights with burns is what is really concerning. Three flights only, in how long? And none of of them even close to the final burn time?

[QuantumG]

Apparently mr. mark didn't. But to add to what parabolicarc is saying, I don't necessarily think that developing alternatives is a sure sign of trouble. But that, taken together with the lengthy delays between test flights with burns is what is really concerning. Three flights only, in how long? And none of of them even close to the final burn time?

Seeing as we're all repeating ourselves on this thread, again... this doesn't necessarily mean there's anything wrong with the engine. In fact, each of the individual parts of the system might be just fine but they don't work well together, yet. One solution might be to change the engine, but that might just introduce new problems too. There's a lot more challenges to SpaceShipTwo than just the engine. More notable, to me, is the scale and complexity of the composites they're using. Too much vibration and the whole airframe will just fall apart.

[JBF]

Seeing as we're all repeating ourselves on this thread, again... this doesn't necessarily mean there's anything wrong with the engine. In fact, each of the individual parts of the system might be just fine but they don't work well together, yet. One solution might be to change the engine, but that might just introduce new problems too. There's a lot more challenges to SpaceShipTwo than just the engine. More notable, to me, is the scale and complexity of the composites they're using. Too much vibration and the whole airframe will just fall apart.

We know a lot more about composites, anything that would shake apart the airframe would destroy a metal one as well.

[QuantumG]

We know a lot more about composites, anything that would shake apart the airframe would destroy a metal one as well.

Nonsense. The kind of composites used in SS2 are sheets joined by epoxies. They have a tendency to slide past each other, which limits their lifetime, in general, and especially so under high vibration or even low vibration at specific frequencies. Metal has no such failure mode.

[Lars_J]

Metal has failure modes too, just different ones than composites. (Metal stress failure points are more easily understood, by being more isotropic by nature, and more experience with them)

Do we have any specific evidence that SS2 is in danger of "falling apart", QuantumG?

[QuantumG]

Metal has failure modes too, just different ones than composites. (Metal stress failure points are more easily understood, by being more isotropic by nature, and more experience with them)

Do we have any specific evidence that SS2 is in danger of "falling apart", QuantumG?

Nothing specific. It was one of the alternate explanations I received when asking people about the motor troubles. There's other issues too.. the most obvious being handling and thermal protection of the liquid nitrous oxide. If the motor is getting too hot at the tank end, that'd be enough to explain their reluctance to do a full duration burn on the test stand, but the solution could be in a tank redesign, not a motor redesign.

[Lee Jay]

Yeah, as I keep saying, the inevitable switch to full liquid rockets is inevitable.

The sooner they get it done, the better!

I'm confused by the pessimism around the hybrids.  These motors, as I understand it, are close cousins to the ones in Dream Chaser, and those have passed all their testing milestones.  Isn't that so?