Quote from: Nindalf on 10/22/2014 03:27 pmSNC hasn't actually decided to change to liquid-fueled engines on Dream Chaser. They just started studying the option.That is not correct. A liquid engine has been baselined for DreamChaser. The Hybrid motor has been abandoned.http://www.parabolicarc.com/2014/08/19/snc-abandons-hybrid-motors-dream-chaser/
SNC hasn't actually decided to change to liquid-fueled engines on Dream Chaser. They just started studying the option.
If SNC is uncertain about DC's engines can we really be surprised if NASA was concerned about a schedule slip?
Not to mention the problems VG has had with SNC built hybrids. The NASA people weren't locked in a vault.
Quote from: docmordrid on 10/22/2014 10:55 pmIf SNC is uncertain about DC's engines can we really be surprised if NASA was concerned about a schedule slip? Investigating alternatives isn't being "uncertain".-
Quote from: docmordridNot to mention the problems VG has had with SNC built hybrids. The NASA people weren't locked in a vault.They're completely different motors.. and completely different vehicles.. for completely different purposes.
Mark Sirangelo stated following from America space interview. http://www.americaspace.com/?p=66192 “We have not announced a change in propulsion systems and that was not a quote from us.”“It was likely meant to refer to our acquisition of Orbitec as we now have an expanded base of propulsion solutions and are exploring their use for future Dream Chaser variants.”“There is no schedule change related to engines.”So the DC is staying with it's existing hybrid engines for the first orbital version at least.
Quote from: clongton on 10/22/2014 04:47 pmQuote from: Nindalf on 10/22/2014 03:27 pmSNC hasn't actually decided to change to liquid-fueled engines on Dream Chaser. They just started studying the option.That is not correct. A liquid engine has been baselined for DreamChaser. The Hybrid motor has been abandoned.http://www.parabolicarc.com/2014/08/19/snc-abandons-hybrid-motors-dream-chaser/Actually, SNC is still making trade studies about the DC engines. Sirangelo refuted (in an interview with AmericaSpace) what was said by Kathy Lueders. No final decision has yet been announced.
Quote from: yg1968 on 10/22/2014 08:01 pmQuote from: clongton on 10/22/2014 04:47 pmQuote from: Nindalf on 10/22/2014 03:27 pmSNC hasn't actually decided to change to liquid-fueled engines on Dream Chaser. They just started studying the option.That is not correct. A liquid engine has been baselined for DreamChaser. The Hybrid motor has been abandoned.http://www.parabolicarc.com/2014/08/19/snc-abandons-hybrid-motors-dream-chaser/Actually, SNC is still making trade studies about the DC engines. Sirangelo refuted (in an interview with AmericaSpace) what was said by Kathy Lueders. No final decision has yet been announced. The decision has been documented. That's all I can say.
Gerstenmaier also disagreed with the members of the source evaluation board about the importance of some planned Dream Chaser features. For example, Gerstenmaier gave less weight to Dream Chaser’s ability to land on runways than did the evaluation board, and was more troubled than the board over some of the remaining technical hurdles in SNC’s proposal.
From the SpaceNews article by Dan Leone:QuoteGerstenmaier also disagreed with the members of the source evaluation board about the importance of some planned Dream Chaser features. For example, Gerstenmaier gave less weight to Dream Chaser’s ability to land on runways than did the evaluation board, and was more troubled than the board over some of the remaining technical hurdles in SNC’s proposal.This hints at the possibility the evaluation board might have come to a preliminary conclusion with recommendations of awards, which might then have been over-ridden by Gerstenmaier. That's speculation, but if it did play out that way the over-ride would look ugly in the court of public opinion, regardless of Gerstenmaier's actual reasons for it.
Space News has an article with additional details on the contract decision I've not seen elsewhere and also on the apparent stand off between NASA and congress.http://www.spacenews.com/article/civil-space/42324house-republicans-clamor-for-commercial-crew-source-selection-documentThis is certainly not where I expected Commercial Crew to be at this point. The more I think about it, the more I think the disparity in the contract amounts ($2 billion!), whatever the technical merits of CST-100, is a potentially big public relations problem for NASA. I hope all this ends well but I'm getting very concerned. A storm seems to be brewing.
Quote from: sdsds on 10/28/2014 04:25 amFrom the SpaceNews article by Dan Leone:QuoteGerstenmaier also disagreed with the members of the source evaluation board about the importance of some planned Dream Chaser features. For example, Gerstenmaier gave less weight to Dream Chaser’s ability to land on runways than did the evaluation board, and was more troubled than the board over some of the remaining technical hurdles in SNC’s proposal.This hints at the possibility the evaluation board might have come to a preliminary conclusion with recommendations of awards, which might then have been over-ridden by Gerstenmaier. That's speculation, but if it did play out that way the over-ride would look ugly in the court of public opinion, regardless of Gerstenmaier's actual reasons for it.Yes, because it would invalidate having an evaluation board in the first place.
Quote from: woods170 on 10/28/2014 07:48 amQuote from: sdsds on 10/28/2014 04:25 amFrom the SpaceNews article by Dan Leone:QuoteGerstenmaier also disagreed with the members of the source evaluation board about the importance of some planned Dream Chaser features. For example, Gerstenmaier gave less weight to Dream Chaser’s ability to land on runways than did the evaluation board, and was more troubled than the board over some of the remaining technical hurdles in SNC’s proposal.This hints at the possibility the evaluation board might have come to a preliminary conclusion with recommendations of awards, which might then have been over-ridden by Gerstenmaier. That's speculation, but if it did play out that way the over-ride would look ugly in the court of public opinion, regardless of Gerstenmaier's actual reasons for it.Yes, because it would invalidate having an evaluation board in the first place.Not at all. The top administrator's job is to make the big decisions on spending, risk vs reward, and so on. But he or she does not have the time (even if they have the expertise) to delve into each designs technical and financial details. So the evaluation board does that - they visit the vendors, look at the designs in detail, check the financials and proposed schedules, and so on. Then they report their data to the administrator, who uses it to make a final decision, which may or may not agree with the board.Lots and lots of processes work this way. The referees review papers, but the editor decides. The decadal review has the scientist's preferences, but the funding agencies decide. Cabinet officers express their views, but the president can decide otherwise. In most cases it's a sensible division of labor, since neither the technical experts or the administrators have the time (and often the ability) to do the other's job well.
It was a little late in the game for a propulsion change. Pretty remarkable how DC went from hybrid-palooza to no hybrids at all!