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#180
by
edkyle99
on 28 Jan, 2015 13:56
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The only ways in which CST-100 had an advantage over Dragon in the source selection document had to do with NASA worrying about development schedule risk. Once NASA has certified both CST-100 and Dragon to carry crew to ISS, there's no legitimate reason to give one company more of the business than the other except price. So Dragon will only be less-flown if it's more expensive. I doubt even you, Ed, think a Dragon flight on Falcon 9 will be more expensive than a CST-100 flight on Atlas V.
Launch price is only part of the equation. Dragon ocean landings are going to present a big challenge - and cost - compared to CST-100 land landings. No one has ever returned crews from such extended time in weightlessness to water landings. Skylab 4 was only 84 days (and then the upside down thing in the photo happened). How will the crews - returning from six months or more in space - be extracted and treated while bobbing on the ocean? How many ships in how many landing zones staffed with how many medical personnel will be required? And so on.
- Ed Kyle
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#181
by
JasonAW3
on 28 Jan, 2015 17:03
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It wouldn't suprise me too much if SpaceX, after getting both the Launch Pad Abort and Onflight Abort certifications, were to switch over to a Dragon V1.9 for at least some Cargo runs. Essentially, this would still, for all internal and operational purposes, be a Dragon V1, but with the SuperDracos and exterior moldlines of the Dragon V2.
Obviously, they would still be using the Dragon V1 substructure as the new docking port has yet to be installed, and the avionics would otherwise have to be changed, but the design lines are similar enough that with a bit of internal weight distribution, the flight and landing characteristics should give meaningful data, up through and including propulsive landings of noncritical return cargoes. Note; initial propulsive firings, ie, "clearing the throats" could be done at a high enough altitude that, if need be, the Dragon could pop 'chutes instead of landing under propulsion.
By doing this, not only is SpaceX still conforming to the "Dragon V1s for cargo", but it also should help gather data and confidence in Dragon V2 landings.
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#182
by
gongora
on 28 Jan, 2015 17:24
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Would be even nicer if they submitted one of their CRS2 types as a cargo Dragon v2 and could start proving the landings that way. I'm sure SpaceX will get some form of landing on land approved during the contract, hopefully before 2020. It's just a matter of how much testing they'll be required to do on their own vs. doing it in the course of paying work. Even with reusable first stages and Dragons, doing landing tests from orbit can't be cheap.
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#183
by
woods170
on 28 Jan, 2015 17:50
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I would imagine no differently than Orion crews returning from Mars.
<sarcasm drive factor 9.5>
Yes sir. SpaceX might be considered to be pathfinders for NASA then.
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#184
by
A_M_Swallow
on 29 Jan, 2015 15:18
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Why does everyone seems to be blaming SpaceX here? Is it not equally likely that NASA got cold feet about SpaceX doing landing landings since they have yet to be tested and asked SpaceX to certify the water landing that they've already had experience with, to give them more confidence in SpaceX's admittedly aggressive test schedule?
In the case of a land landing the objection may be coming from elsewhere such as the FAA, the state government and/or the county council. The Dragon V2.0 is probably going through similar bureaucratic problems to the Falcon 9R.
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#185
by
AS_501
on 29 Jan, 2015 15:57
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FWIW, there was a 2089-day "gap" in U.S. manned spaceflight between the end of ASTP and STS-1. The same gap after the STS-135 landing is the end of March, 2017. If Boeing or Space-X don't meet that date, we will have the longest-yet gap in U.S. capability. On the other hand, this should be the last gap in U.S. manned spaceflight history (we hope).
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#186
by
rcoppola
on 29 Jan, 2015 23:17
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Concerning landings:
Certainly the DragonFly program will be crucial to proving out D2s assisted and full propulsive landings. There's very little room in their certification schedule. Yes they have stated margin in their schedule but that's not going to remain for propulsive (assisted or full) landings.
Also, it' not just about SDs, you've got those legs that poke through the heat shield and act as shock absorbers.
Not necessarily a huge engineering lift but just another item to add to an already tight certification schedule. And that doesn't include the redundant avionics for SD landings and associated testing. Needless to say, I don't think any of this is beyond what SpaceX can or will do, just beyond what the current certification schedule will allow. Something had to give and they already will be dealing with certifying their own designed spacesuits and docking mechanism as well as there unconventional approach of not using traditional rad hardened electronics, something NASA has very strong reservations about already.
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#187
by
Chris Bergin
on 30 Jan, 2015 11:13
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#188
by
Star One
on 30 Jan, 2015 12:10
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#189
by
kevinof
on 30 Jan, 2015 12:35
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Couldn't agree more. SpaceX, Nasa and almost everyone here want's to see crew flying on Dragon and CST asap and sometimes you have to walk before you can run. If something has to slip then powered landings must be it - let's get something flying safely and then keep tweaking until you get to the end goal of fully powered landings.
Concerning landings:
Certainly the DragonFly program will be crucial to proving out D2s assisted and full propulsive landings. There's very little room in their certification schedule. Yes they have stated margin in their schedule but that's not going to remain for propulsive (assisted or full) landings.
Also, it' not just about SDs, you've got those legs that poke through the heat shield and act as shock absorbers.
Not necessarily a huge engineering lift but just another item to add to an already tight certification schedule. And that doesn't include the redundant avionics for SD landings and associated testing. Needless to say, I don't think any of this is beyond what SpaceX can or will do, just beyond what the current certification schedule will allow. Something had to give and they already will be dealing with certifying their own designed spacesuits and docking mechanism as well as there unconventional approach of not using traditional rad hardened electronics, something NASA has very strong reservations about already.
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#190
by
AncientU
on 30 Jan, 2015 15:43
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Couldn't agree more. SpaceX, Nasa and almost everyone here want's to see crew flying on Dragon and CST asap and sometimes you have to walk before you can run. If something has to slip then powered landings must be it - let's get something flying safely and then keep tweaking until you get to the end goal of fully powered landings.
Concerning landings:
Certainly the DragonFly program will be crucial to proving out D2s assisted and full propulsive landings. There's very little room in their certification schedule. Yes they have stated margin in their schedule but that's not going to remain for propulsive (assisted or full) landings.
Also, it' not just about SDs, you've got those legs that poke through the heat shield and act as shock absorbers.
Not necessarily a huge engineering lift but just another item to add to an already tight certification schedule. And that doesn't include the redundant avionics for SD landings and associated testing. Needless to say, I don't think any of this is beyond what SpaceX can or will do, just beyond what the current certification schedule will allow. Something had to give and they already will be dealing with certifying their own designed spacesuits and docking mechanism as well as there unconventional approach of not using traditional rad hardened electronics, something NASA has very strong reservations about already.
Seems to me that the land landing under parachute with a burst of Super-dracos at the end was a compromise from the start. The angle induced by the off-center tether point plus the potential horizontal speed would make this landing subject to significant risk. Going with water landing is better than the kluge of a land landing under parachute. (This doesn't mean I'm not disappointed.)
Dragon 2 was designed for propulsive landings... anything short of that is a pragmatic, near-term solution to satisfy the delivery date and/or NASA's hyper-risk aversion.
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#191
by
te_atl
on 30 Jan, 2015 17:29
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I've avoided the "they'll land on land....what gives SpaceX?" as while it's not a massive issue, I do agree with QG about the lack of an explanation.... but I want to ask SpaceX for an official comment before I represent it (or misrepresent it, which is what I really don't want to do).
Standalone thread for the article:
http://forum.nasaspaceflight.com/index.php?topic=36680.0
Chris, go back and check your article
http://www.nasaspaceflight.com/2013/07/dragon-roadmap-domestic-crew-independence-humans-mars/When you wrote that, you quoted SpaceX's Christine Ra as saying "SpaceX certainly sees value in implementing a propulsive landing system prior to crew launches but timing for implementation will be something we discuss with NASA as they are the primary customer for both types of flights,”
So this isn't a new thing.
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#192
by
bad_astra
on 30 Jan, 2015 21:17
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Really enjoyed the article Chris. The optimism of the key players is getting infectious. I am really looking forward to the next few years.
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#193
by
QuantumG
on 30 Jan, 2015 23:26
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I don't know what I have to keep repeating this. The intermediate landing method for Dragon was supposed to be parachutes and shock absorbing legs - i.e., comparable to Boeing's parachutes and airbags. Garrett Reisman told us back in September last year. It wasn't parachutes and bursts of SuperDracos. It never was. Stop saying it was.
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#194
by
docmordrid
on 31 Jan, 2015 00:38
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I don't know what I have to keep repeating this. The intermediate landing method for Dragon was supposed to be parachutes and shock absorbing legs - i.e., comparable to Boeing's parachutes and airbags. Garrett Reisman told us back in September last year. It wasn't parachutes and bursts of SuperDracos. It never was. Stop saying it was.
Steve Jurvetson at NewSpace 2012
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#195
by
clongton
on 31 Jan, 2015 21:36
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And so there we have it folks. It will begin with parachute descent and as the vehicle approaches touchdown the super dracos will fire to stabilize and orient the spacecraft and then gently lower the vehicle to the ground. BTW that is exactly what Soyuz does today (just not as gently) and NASA has yet to complain! So I don't see them being concerned with the SpaceX plan.
It was specifically stated in the video that fully propulsive landing is the ultimate goal.
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#196
by
QuantumG
on 31 Jan, 2015 23:06
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Steve Jurvetson at NewSpace 2012
September 2014 beats NewSpace 2012!
Your video doesn't even have a Dragon 2 in it.
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#197
by
docmordrid
on 31 Jan, 2015 23:22
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Steve Jurvetson at NewSpace 2012
September 2014 beats NewSpace 2012!
Your video doesn't even have a Dragon 2 in it.
Of courtside it doesn't, they hadn't announced 'Dragon 2' yet but that doesn't mean it wasn't ' the plan!' What it does document though is that 2+ years ago they were talking about a water or land propulsive assisted parachute landing with a 'Crew Dragon' whatever it's designation, so stop claiming they never were.
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#198
by
QuantumG
on 31 Jan, 2015 23:26
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2+ years ago they were talking about a water or land propulsive assisted parachute landing with a 'Crew Dragon' whatever it's designation, so stop claiming they never were.
I never debated that. Who cares? This thread is about the Dragon 2 and the CST-100.
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#199
by
AS-503
on 01 Feb, 2015 00:37
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I don't know what I have to keep repeating this. The intermediate landing method for Dragon was supposed to be parachutes and shock absorbing legs - i.e., comparable to Boeing's parachutes and airbags. Garrett Reisman told us back in September last year. It wasn't parachutes and bursts of SuperDracos. It never was. Stop saying it was.
Parachutes and landing legs ONLY is for worst case scenario 3 sigma wind case during pad abort!
That mode was NEVER intended as the “intermediate landing method” as you state.
Maybe you shouldn't "keep repeating it".
August 27, 2014
http://www.parabolicarc.com/2014/09/02/video-garrett-reismans-presentation-spacex-programs/@ 26:05
Reisman: “Dragon has landing legs, and that’s what we use to take up the final…we land on land under parachutes…um..and then use the Super Draco launch abort system to provide cushioning…uh…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.”
@ 26:43
Questioner: “On the use of the Super Dracos for the final touchdown. If you have aborted, does that mean..uh..that the engines are no longer available so you could only abort in the water? Or what happens if you do land on land after an abort?”
Reisman: “That’s correct…um..we, we…well two things, the plan for a nominal abort…we say that all the time and it always makes me kinda wonder what that means…but the nominal abort..uh..is in the water. So even a pad abort is designed to get you to the water. And certainly anything, uh, that happens along the trajectory is designed to get you to the water……anytime you have to light the Super Dracos for an abort you end up splashing down. However, if you exceed a three sigma wind case (during a pad abort) and drift on to shore the good news is that the landing, the whole landing system is designed so that it’s, um, survivable if there’s no propulsive assist at all. So if you come down chutes only with the landing legs, uh, we, we anticipate no crew injury. But I will be, basically it will be kinda like landing in a Soyuz. (Laughs) You’ll know that you’ve reached the Earth.”
