Jim, a question... Cannot SNC fit whatever sized nozzle to which ever part of the flight envelope they wish to test? It is a bolt-on operation...
Quote from: Rocket Science on 12/30/2012 01:01 pmJim, a question... Cannot SNC fit whatever sized nozzle to which ever part of the flight envelope they wish to test? It is a bolt-on operation...Most nozzles for composite SRM's aren't bolt-on
And isn't CST-100 using RS-88 for both abort (from sea level presumably) and orbital maneuvering, i.e. vacuum?
Quote from: Jim on 12/30/2012 01:43 pmQuote from: Rocket Science on 12/30/2012 01:01 pmJim, a question... Cannot SNC fit whatever sized nozzle to which ever part of the flight envelope they wish to test? It is a bolt-on operation...Most nozzles for composite SRM's aren't bolt-on Yea Jim you are right . I was thinking about the bolts around the circumference on the end case on the ground test motors. The motors are one piece composite. In that case they would have to produce motors with different optimized nozzles....Edit to add:Thinking about this a bit more... DC would have to be able to perform a Pad Abort using standard ops motors and nozzles. So why can’t a single nozzle design be used for the test flights as well?
In a DC thread some time ago people expressed doubt that one nozzle design could be chosen that would work in vacuum and the atmosphere. I'm not sure if this is in fact that big a problem (shuttle SRM nozzle operated from 0-146K ft without trouble) but if it is, then the hybrids couldn't be used for drop tests
Quote from: adrianwyard on 12/29/2012 09:51 pmIn a DC thread some time ago people expressed doubt that one nozzle design could be chosen that would work in vacuum and the atmosphere. I'm not sure if this is in fact that big a problem (shuttle SRM nozzle operated from 0-146K ft without trouble) but if it is, then the hybrids couldn't be used for drop tests I asked them specifically if the hybrids would be used for the drop tests, and Mark Sirangelo said that they would be. I think it's reasonable to assume that he knows what he's talking about given that he's former CEO of Spacedev and current head of SNC Space Systems.This was in the context of high altitude releases from carrier aircraft, not from the helicopter.
Quote from: Lee Jay on 12/31/2012 03:00 amQuote from: adrianwyard on 12/29/2012 09:51 pmIn a DC thread some time ago people expressed doubt that one nozzle design could be chosen that would work in vacuum and the atmosphere. I'm not sure if this is in fact that big a problem (shuttle SRM nozzle operated from 0-146K ft without trouble) but if it is, then the hybrids couldn't be used for drop tests I asked them specifically if the hybrids would be used for the drop tests, and Mark Sirangelo said that they would be. I think it's reasonable to assume that he knows what he's talking about given that he's former CEO of Spacedev and current head of SNC Space Systems.This was in the context of high altitude releases from carrier aircraft, not from the helicopter.Exactly Lee Jay, I remember that and that is one of the reasons that I fail to understand the concern over it. The only difference that it would be done later in the test flights as Mark stated. Circumstances have changed and perhaps other options made need to be examined including boost to climb sooner rather than later...
Quote from: adrianwyard on 12/30/2012 06:30 amIf the RCS can also operate at all altitudes, No such thing.
If the RCS can also operate at all altitudes,
Quote from: Jim on 12/30/2012 12:53 pmQuote from: adrianwyard on 12/30/2012 06:30 amIf the RCS can also operate at all altitudes, No such thing.Do you say this because it's not possible to design one nozzle that's optimized for all ambient pressures? Or for some other reason?
I see the Shuttle orbiter's vernier jets were a scant 25 pounds-force, and main RCS jets were 860 pounds-force. Since DC is ~1/10th the mass of the orbiter, can we guess its' RCS will be closer in size to the Shuttle's verniers?