Quote from: meekGee on 08/25/2014 04:29 pmQuote from: Ben the Space Brit on 08/25/2014 01:50 pmWell, I suppose it would have really been 'v.1.5' as it would have had the LAS motor pods and an ECLSS added as originally intended. My speculation is that the list of things to do to get v.1 crew-ready was getting longer and, combined with negative rumbles about getting the CCrew contract, Elon decided it would be more cost-efficient to build an optimised crew variant rather than a modified cargo version used for crew.How do you know that the v2 isn't "really" a v1.5?It has Super Dracos with fancy fairings (which are not part of the pressure vessel), life support, seating, flight controls, new hatch, docking adapter...But all of these are on the minimal-change list from 1.0 to "1.5" anyway.What pushes it over the edge to becoming "totally new"?The only thing I can see that makes it a v2 is that they've decided to present it as such.There was a long argument 1-2 years ago about what the crewed Dragon would look like, and this is pretty much along the mid-range of the opinions. It does not have wings, it still has a drop-off trunk...It's all a matter of perception.My only caution would be a few data points:1. Garett said a few weeks ago that they hit a few snags along the way. 2. IIRC, they are still working towards their Primary Structures Qualification. I'm only thinking that perhaps attaching the SDs to the primary structure and all the added stresses that implies, necessitated enough core design changes that the very underlying structures have been modified to a greater extent then we are aware of. Not counting how they redesigned the entire parachute system and placement, modified plumbing, wiring/electric, outer mold-lines , fuel storage, TPS/ landing legs and trunk.Start adding all that up and it's like going from Gemini to Apollo. (or not)
Quote from: Ben the Space Brit on 08/25/2014 01:50 pmWell, I suppose it would have really been 'v.1.5' as it would have had the LAS motor pods and an ECLSS added as originally intended. My speculation is that the list of things to do to get v.1 crew-ready was getting longer and, combined with negative rumbles about getting the CCrew contract, Elon decided it would be more cost-efficient to build an optimised crew variant rather than a modified cargo version used for crew.How do you know that the v2 isn't "really" a v1.5?It has Super Dracos with fancy fairings (which are not part of the pressure vessel), life support, seating, flight controls, new hatch, docking adapter...But all of these are on the minimal-change list from 1.0 to "1.5" anyway.What pushes it over the edge to becoming "totally new"?The only thing I can see that makes it a v2 is that they've decided to present it as such.There was a long argument 1-2 years ago about what the crewed Dragon would look like, and this is pretty much along the mid-range of the opinions. It does not have wings, it still has a drop-off trunk...It's all a matter of perception.
Well, I suppose it would have really been 'v.1.5' as it would have had the LAS motor pods and an ECLSS added as originally intended. My speculation is that the list of things to do to get v.1 crew-ready was getting longer and, combined with negative rumbles about getting the CCrew contract, Elon decided it would be more cost-efficient to build an optimised crew variant rather than a modified cargo version used for crew.
Remember: This decision will be at least partly made based on politics and perception. Boeing is nearly-guaranteed selection because they're Boeing; problems with CST-100 will be considered second, if at all, out of fear of Shelby et al defunding the program. Because perception is the key, the implication that v.2 is a near-fully-new design will work against it, in my view.
While your scenario has its appeal, I believe someone from NASA was quoted saying they are not planning on handing out half awards for CCtCAP.
This whole discussion of V2 reminds me of almost every SpaceX development program....snip...So, Over promise, under deliver, then promise more, and deliver it. That seems like the secret in a nutshell.
In Dragon V2 case, they are delivering a potentially overqualified vehicle at the lowest cost (assuming the pattern follows from previous rounds).
End result is a somewhat future-proofed operational product capable of uses beyond ISS and potentially fully reusable.
I don't know about "future-proofed". For all we know just as the Dragon V1 was a pathfinder for the Dragon V2, the V2 is probably a pathfinder for the V3.
Quote from: Mariusuiram on 08/26/2014 03:31 amThis whole discussion of V2 reminds me of almost every SpaceX development program....snip...So, Over promise, under deliver, then promise more, and deliver it. That seems like the secret in a nutshell.The problem with your assertion is that you don't know what SpaceX customers were promised. And they are the only ones that matter. It doesn't matter what we think SpaceX has "promised" or not.
And from what I can remember, SpaceX has not under-delivered on performance, just been later than their public goals.
Every product is developed relatively quickly & cheaply with big promises and big margins. There are inevitably problems because of the pace & target (or maybe inexperience) causing delays.
This whole discussion of V2 reminds me of almost every SpaceX development program.[...]So, Over promise, under deliver, then promise more, and deliver it.
To be fair, he didn't say they promised it to customers......I don't think you two are disagreeing, just phrasing it differently. The "then promise more, and deliver it" part implies that SpaceX eventually did deliver on their original promise.
We land on land under parachutes and then use the SuperDraco launch abort system to provide cushioning for the final touchdown. And then we have landing legs that are designed to take up any residual load and allow us to land on a variety of different surface hardnesses.
However, if you exceed a three-sigma wind case and drift onto shore, the good news is that the landing, the whole landing system is designed so that it's survivable if there's no propulsive assist at all. So if you come down chutes only with the landing legs, we anticipate no crew injury. But it will be, you know, basically, it'll be kind of like landing in the Soyuz. It'll be... You'll know that you've reached the earth.
Yeah, and it's really, the propulsive assist is really just in the final descent and landing really within the last few seconds otherwise it's parachute all the way down.
Dr Riesman did not elaborate on why they will land with parachutes. Elon has been pretty adamant about full propulsive landings. Either it does not work, or NASA said no thanks to something that radical.
Quote from: GalacticIntruder on 08/28/2014 12:33 amDr Riesman did not elaborate on why they will land with parachutes. Elon has been pretty adamant about full propulsive landings. Either it does not work, or NASA said no thanks to something that radical.It's just the incremental process. Would ya prefer they wait until propulsive landings are mature before flying anyone?