Narrowing the CCDev candidate list

[go4mars]

The reinforcement would need to be above, to the nose of the craft due to the stresses involved.  They could indeed have accounted for this already, but then the work for the LAS makes less sense, as that would need to have been designed and tested already, unless they deliberately made Dragon overweight in order to buy the margin they would later need, which would harm their cargo contract.

Many future features appear to have been built in for a long time.  Structure for legs (I think), windows, and BEO heatshield.  The fact that early renderings (post-Gary Hudson's design) had a tractor abort system suggests that they didn't think of adding the noses until at least some of the initial design work had been done.  So you might be right. 

On the other hand, I think its been at least 2 or 3 years that Elon's been proudly mentioning his clever LAS solution (dual purpose fuel tanks, abort capability all the way up, no tractor tower falling off every flight, ability to do propulsive landings, extra redundancy by having 8 thrusters, ability to maximize friction in rarified martian air at supersonic speeds (okay he hasn't elaborated much on that last one)).     

Maybe I'm wrong, but I would guess that in the last few years, Elon and his gang of lofty brains have been considering this very concern. 

It seems to me that a simple solution, such as a force-transfer bracket along the inside of the pressure hull to strong enough places (whether up by the berthing adaptor or down by the leg/heatshield nether-regions or both), would do the trick without redesigning the whole shebang. 

I don't believe that a fundamental redesign of the pressure hull is necessary or likely for the nose version.

A question: If the pressure hull can handle re-entry and splashdown, does that imply structural elements exist that could handle the force of 4 noses blowing as hard as they can?

[Downix]

A question: If the pressure hull can handle re-entry and splashdown, does that imply structural elements exist that could handle the force of 4 noses blowing as hard as they can?

Having dropped more than one item into a water tank at high speed before, and more than one launched into the air with high force (a few intentionally even), no, the stresses involved are quite different.  One is a compressive force, the other is a tension force.  Balancing them is an art form unto itself, as any bridge builder can tell you.  Doing so with a weight premium imposed, that is a high art on the level of Da Vinci himself.

[jongoff]

But you failed to refute.  Instead, you claimed that there was no mold line change, as in quotes above.  I pointed out that there was a mold line change, and then gave the resulting structural changes needed to accept that.  It changes enough that there is no longer an in existence pressure vessel to match the spaceflight form, which puts it behind CST-100 and DC which both offer that, in my viewpoint.

Yes, you are correct, there will be a mold line change. That we can agree on. My bad.

But you go on here (again) to make another claim - that this mold line change implies a pressure vessel change. This is an assertion I find more troubling.
1) this is far from certain - depends on the exact size and location of the superdraco thrusters.
2) even if true, is a pressure vessel change more important/difficult than a mold line change? I really don't know, so feedback from experienced ones would be helpful.

I'm kind of doubtful this is a showstopper. SpaceX has demonstrated that their crew are perfectly capable of designing and analyzing complex pressure vessels and structures from scratch. I really don't think that the pressure vessel or structure changes are the high-risk, high-development items in implementing SuperDraco powered-landing. I think the whole "powered-landing" part is the hard part... But I'm not too worried about them getting that figured out either.

~Jon

[jongoff]

Spaceships are for BEO.. direct reentry is nice, but is it worth it?

It will be the way for many years.  Can't afford the delta V to enter LEO from BEO.

*cough* aerocapture *cough*

Sure it's not as high of TRL as direct entry, but that's mostly because nobody has actually tried to demo it. All the underlying technology pieces are there, it's just engineering from here.

~Jon

[joek]

My take (and please, don't take the editorializing too seriously)...

A. Very high importance - lowest program risk: Who will pass the finish line in time to matter [regardless of cost]?
1. Boeing (mature, old reliable)
2. SpaceX (fast rising but still the new kid)
3. SNC (potential, past puberty, but still a wildcard)

B. Medium importance - lowest program cost to NASA: Who is hungriest and willing to put the most money in the pot?
1. SpaceX (It's all in our name: all space, all the time.  pssst... IPO.)
2. SNC (Don't touch me there... and look at it, ain't it purrty!)
3. Boeing (So we make a few hundred mil in a few years... *yawn*)

C. Low importance - lowest potential future service cost to NASA: Who is most likely to succeed at turning this into a commercially successful venture in the future?"
1. SpaceX (LEO? Heck, We got commercial plans for Mars buddy!)
2. SNC (Everyone will want to fly in it... ain't it purrty! )
3. Boeing (Who said "commercial"? You're in the wrong division pal.)

Final rank:
1. Boeing
2. SpaceX
3. SNC

[Downix]

But you failed to refute.  Instead, you claimed that there was no mold line change, as in quotes above.  I pointed out that there was a mold line change, and then gave the resulting structural changes needed to accept that.  It changes enough that there is no longer an in existence pressure vessel to match the spaceflight form, which puts it behind CST-100 and DC which both offer that, in my viewpoint.

Yes, you are correct, there will be a mold line change. That we can agree on. My bad.

But you go on here (again) to make another claim - that this mold line change implies a pressure vessel change. This is an assertion I find more troubling.
1) this is far from certain - depends on the exact size and location of the superdraco thrusters.
2) even if true, is a pressure vessel change more important/difficult than a mold line change? I really don't know, so feedback from experienced ones would be helpful.

I'm kind of doubtful this is a showstopper. SpaceX has demonstrated that their crew are perfectly capable of designing and analyzing complex pressure vessels and structures from scratch. I really don't think that the pressure vessel or structure changes are the high-risk, high-development items in implementing SuperDraco powered-landing. I think the whole "powered-landing" part is the hard part... But I'm not too worried about them getting that figured out either.

~Jon

Never said a showstopper, only that it is a step that needs to be done, and that gives them a few more steps to readyness than the others by my estimate.  Only a few, mind you, and with how eager SpaceX is I suspect that they will close this gap before CCDev3 is completed.  But yes, it is the powered landing which is the real worry part, although thankfully they can fall back on water landing which they have already demonstrated.

[JNobles]

But you failed to refute.  Instead, you claimed that there was no mold line change, as in quotes above.  I pointed out that there was a mold line change, and then gave the resulting structural changes needed to accept that.  It changes enough that there is no longer an in existence pressure vessel to match the spaceflight form, which puts it behind CST-100 and DC which both offer that, in my viewpoint.

Yes, you are correct, there will be a mold line change. That we can agree on. My bad.

But you go on here (again) to make another claim - that this mold line change implies a pressure vessel change. This is an assertion I find more troubling.
1) this is far from certain - depends on the exact size and location of the superdraco thrusters.
2) even if true, is a pressure vessel change more important/difficult than a mold line change? I really don't know, so feedback from experienced ones would be helpful.

I'm kind of doubtful this is a showstopper. SpaceX has demonstrated that their crew are perfectly capable of designing and analyzing complex pressure vessels and structures from scratch. I really don't think that the pressure vessel or structure changes are the high-risk, high-development items in implementing SuperDraco powered-landing. I think the whole "powered-landing" part is the hard part... But I'm not too worried about them getting that figured out either.

~Jon

Never said a showstopper, only that it is a step that needs to be done, and that gives them a few more steps to readyness than the others by my estimate.  Only a few, mind you, and with how eager SpaceX is I suspect that they will close this gap before CCDev3 is completed.  But yes, it is the powered landing which is the real worry part, although thankfully they can fall back on water landing which they have already demonstrated.

There's something else that I'm not sure how to understand properly.  NASA has got to be in-the-know about changes to Dragon to make it Dragonrider.  Yet we haven't heard any cautionary statements from them about a new or heavily altered design.  They seem to be treating Dragonrider, with its fire-breathing nostrils, as a change barely worth mentioning in public.  I'm not sure how to take that.

Same thing with Falcon v.1.1.  A stretched vehicle with other changes and yet it is going to be interchangeable with v.1.0 starting with CRS 3?  Do they regard these types of changes as minimal and not really a concern?

I'm a SpaceX fan but I don't understand why things are coming down this way.

[joek]

There's something else that I'm not sure how to understand properly.  NASA has got to be in-the-know about changes to Dragon to make it Dragonrider.  Yet we haven't heard any cautionary statements from them about a new or heavily altered design.  They seem to be treating Dragonrider, with its fire-breathing nostrils, as a change barely worth mentioning in public.  I'm not sure how to take that.

NASA would be way out of line to make such statements in public (or in private except to those directly involved).

[beancounter]

There's something else that I'm not sure how to understand properly.  NASA has got to be in-the-know about changes to Dragon to make it Dragonrider.  Yet we haven't heard any cautionary statements from them about a new or heavily altered design.  They seem to be treating Dragonrider, with its fire-breathing nostrils, as a change barely worth mentioning in public.  I'm not sure how to take that.

NASA would be way out of line to make such statements in public (or in private except to those directly involved).

Apart from the comment around NASA, the question is really about the contract.  Under the SAA, NASA is not telling the providers in CCDev how to design and build their vehicles, only what they must be capable of doing, which is, so I understand, significantly different to a FAR contract. 

[Prober]

It is most unfortunate that we're likely to end up with exactly what I feared - capsules stuck in Low Earth Orbit.  If we're going to be stuck in LEO for another decade or more, I'd rather see some progress on the spaceplane front.  So, I do hope SNC beats the odds.  It's a shame that Boeing entered the race with the pointless, redundant CST-100 instead of, say, an X-37 derived crew vehicle.

Don't wind me up and get me started....heheh

[Prober]

It is most unfortunate that we're likely to end up with exactly what I feared - capsules stuck in Low Earth Orbit.  If we're going to be stuck in LEO for another decade or more, I'd rather see some progress on the spaceplane front.  So, I do hope SNC beats the odds.  It's a shame that Boeing entered the race with the pointless, redundant CST-100 instead of, say, an X-37 derived crew vehicle.

"Derived" would be the key word there.

Would have to be essentially a totally new vehicle.

Such a vehicle, the X-37C has been proposed by some at Boeing but not as an official CCDev proposal:
http://forum.nasaspaceflight.com/index.php?topic=27010.0

Do we know for sure a sub group within Boeing did not submit?

[Jim]

Do we know for sure a sub group within Boeing did not submit?

Yes, because Boeing isn't going to compete with itself

[Prober]

It is most unfortunate that we're likely to end up with exactly what I feared - capsules stuck in Low Earth Orbit.  If we're going to be stuck in LEO for another decade or more, I'd rather see some progress on the spaceplane front.  So, I do hope SNC beats the odds.  It's a shame that Boeing entered the race with the pointless, redundant CST-100 instead of, say, an X-37 derived crew vehicle.

"Derived" would be the key word there.

Would have to be essentially a totally new vehicle.

No, the X-37 scales real well.     A pressure vessel would be the only major new item, and sure Boeing would be up to the task for that.

[Jim]

No, the X-37 scales real well.     A pressure vessel would be the only major new item, and sure Boeing would be up to the task for that.

No, scaling has nothing to do with it.  It is all new hardware.  Nothing structure was it usable for the C.  That is meant by new vehicle.

[Prober]

an X-37 derived crew vehicle.

Which would really make us stuck in LEO. 

Wings are for LEO and capsules are for BEO.

Mostly true, however a paper study was done regarding the x-37.  Few talk about it, maybe because the paper is not public and must be purchased from the AAIA.  It's for a Lunar X-37.  If you want the name let me know i can look it up.

[Lurker Steve]

Do we know for sure a sub group within Boeing did not submit?

Yes, because Boeing isn't going to compete with itself

Or they had an internal competition and made a selection before submitting the original CCDev bid to NASA.

I'm sure Boeing has a bunch of spacecraft designs sitting on their virtual shelfs. The CST-100 came from the original Orion competition with LM, right ? Perhaps someone at Boeing looked at the business case and decided that it would cost less to complete the capsule design.

Besides, the X-37 work is still being funding by the Air Force. I'm sure someone said they don't want to mess with a current DoD contract. Any changes for commerical crew might conflict with the Air Force mission.

[Jim]

I'm sure Boeing has a bunch of spacecraft designs sitting on their virtual shelfs. The CST-100 came from the original Orion competition with LM, right ? Perhaps someone at Boeing looked at the business case and decided that it would cost less to complete the capsule design.

Actually, OSP.

[Prober]

Do we know for sure a sub group within Boeing did not submit?

Yes, because Boeing isn't going to compete with itself

Besides, the X-37 work is still being funding by the Air Force. I'm sure someone said they don't want to mess with a current DoD contract. Any changes for commerical crew might conflict with the Air Force mission.

Most of the development costs were funded by Boeing.   The test/use program is funded by the USAF.

That’s something to be taken into account in this process.  If Boeing is serious about Commercial, they will fund it.

[docmordrid]

ISTM that SNC's Dream Chaser meets many / most of the specs for "X-37C" and is well along in development.

[Prober]

ISTM that SNC's Dream Chaser meets many / most of the specs for "X-37C" and is well along in development.

Yeah, DC is impressive, and the company did alot with little cash from NASA.

Major difference that would put the X-37 at the top of the pack is the testing.