SpaceX's Dragon capsule captured by ISS

[Skipjack]

Griffin had the plan for Constellation already before he became NASA administrator.
And just because you are the administrator, you dont OWN NASA. NASA is owned by the people of the United States and Griffin had no right to push his own agenda.

The completely reusable design had already been shown would be much more expensive, so maintaining it would have been cheaper is just stupid. The various assemblies that were considered, all had the problem that ice shed off the tank would hit the orbiter, so pretending Phoenix was a consideration is stupid. It was never a serous contender. You want to blame Shuttle and pretend it displaced better designs, but those designs were never considered seriously because they were considered too advanced.

http://en.wikipedia.org/wiki/File:North ... l_P333.jpg

Phoenix and its variations were not contenders because they could not fullfill the requirement of crossrange.
There was also SERV and OART-MAD and tons of other concepts that were quite realistic but often had a smaller payload and/or not enough crossrange.

I would have loved to see something like the ATV or the SASSTO as a first manned RLV for the transport of small crews to orbital space stations. Their capabilities would have been limited, but they would have been a first step to build on. With a gradually expanded envelope and improved capabilities with every generation. Since they would have been comparably small and cheap to develop, one could have updated them frequently. A two man crew could have turned into a 7 man crew like Dragon does, but on a full SSTO RLV.
http://www.spacefuture.com/archive/hist ... tems.shtml

In the 90ies NASA had another chance to make up for its past mistakes and support the DC-X program. Instead they cancelled it and focused on the- again- much more ambitious Venture Star (with the suborbital X33 prototype). Again they insisted on requirements that were way to high for a first vehicle and again they failed.

Also I have to object to the idea that a space station is not possible without a vehicle that has ALL the capabilities of the space shuttle. Skylab did not need the shuttle, Mir did not need it and Bigelow wont need it either.

[Joseph Chikva]

Obviously you still don't get that what went up could come down. It is not a micro capsule parachuting in. It is a fully functional vehicle with massive payload bay that can take stuff up, and, BRING STUFF DOWN, in a controlled manner. Single use vehicles bring little things back, sometimes, and not always in a controlled manner.

You have not necessity to explain to me obvious things. Simply I say that if the program is stopped and USA still has demand to transport cargoes in space and back and also to do some manipulations there, Shuttle isn't so irreplaceable. And the preference is given to cheaper and safer solution.

[Joseph Chikva]

Obviously you still don't get that what went up could come down. It is not a micro capsule parachuting in. It is a fully functional vehicle with massive payload bay that can take stuff up, and, BRING STUFF DOWN, in a controlled manner. Single use vehicles bring little things back, sometimes, and not always in a controlled manner.

You have not necessity to explain me the obvious things. Simply I say that if the program is stopped and USA still has demand to transport cargoes in space and back and also to do some manipulations there, Shuttle isn't so irreplaceable. And the preference is given to cheaper and safer solution.

[GIThruster]

Griffin had the plan for Constellation already before he became NASA administrator.
And just because you are the administrator, you dont OWN NASA. NASA is owned by the people of the United States and Griffin had no right to push his own agenda.

You're pretty confused. Griffin had his own opinion and was hired for it. He pursued it. You're whining like a small child because he didn't do what you think he should have done, and in your next breath you'd reserve just exactly that same right to someone like Von Braun. Don't kid yourself, Griffin had every right to do what he thought was best. He didn't "hijack" the program. He was in the place to make the recommendation to POTUS for whatever he thought was best and given permission, to pursue that program.

Phoenix and its variations were not contenders because they could not fullfill the requirement of crossrange.

Do you make this up as you go along or did you find someone else as misinformed as you are? I already explained twice, things like Phoenix were passed over BEFORE DOD got involved. They were passed over because all the early studies in 50's had shown what a lifting body could do, and the idea of tail landing a capsule was considered too challenging. Basically, the precise opposite of what you're claiming. FYI, tail landing a rocket is extremely hazardous because you can't see what you're doing, and they didn't have the technology 40 years ago to do what you're claiming would have been less challenging. They did have the technology to build the Shuttle.

BTW, there was a later program that given the technology of its day, decided VTOL was the way to go. The Strategic Defense initiative Organization decided that VTOL was right on and wanted to pursue it. This was however, 20 years too late to avoid Shuttle. The arguments you're making about crossrange being the devil come from the SDIO days.

IMHO, the biggest problem with spaceplanes is they can't land without atmosphere. If you want to go to the Moon, Mars etc., you have to develop the tail landing craft anyway, so they really are better for here as well if you have the technological prowess. We did not have the technological prowess 40 years ago. In fact, there is still plenty of doubt that we have it now.

[Joseph Chikva]

rrr

[Skipjack]

Griffin had his own opinion and was hired for it.

Yeah, he did, mainly from his previous non- NASA positions and connections to ATK (through Orbital Sciences and his work for the Planetary society, where had previously planned the Constellation system). He was quite obviously biased and he cancelled O'Keefes plan that saw two competing suppliers. Naturally Griffins sole source provider plan went over budget and was behind schedule. Besides, I always thought of it as a step back not forward.

Do you make this up as you go along or did you find someone else as misinformed as you are? I already explained twice, things like Phoenix were passed over BEFORE DOD got involved. They were passed over because all the early studies in 50's had shown what a lifting body could do, and the idea of tail landing a capsule was considered too challenging.

You mean like landing a LEM on the moon?
I see...

Did you read any of the links that I posted? You did not, because you think that you already know it all. Hu?

FYI, tail landing a rocket is extremely hazardous because you can't see what you're doing

It is challenging but there are solutions for that, you know. It is certainly less of a challenge than those that the shuttle faced.

BTW, there was a later program that given the technology of its day, decided VTOL was the way to go. The Strategic Defense initiative Organization decided that VTOL was right on and wanted to pursue it. This was however, 20 years too late to avoid Shuttle.

Yes, it was the DC-X that I mentioned earlier. Again, you did not even read what I said, or the links that I posted.

You should read up on the issues with winged spacecraft. They contributed quite a bit to the issues of the shuttle (leading edge heating, etc). I am convinced that the Dreamchaser will have simillar problems with this. They are already facing long maintenance times due to the many TPS- tiles that they will need. I was originally hoping that they would not and I was quite disappointed when I read that maintenance times between flights will be two months. That is quite long for such a small craft.
It is the price that you pay for the crossrange (whether it is needed or not is a different story).
We will see whether this will allow them to remain competitive. Their vehicle has some advantages over the others that might keep them in the race, but 2 months maintenance is a killer.

[GIThruster]

Well for once we're agreed. Tile maintenance is prohibitively expensive. I'm surprised we're not seeing something closer to X-33 in the competition and have to wonder if L-M will step forward with one. The benefit from the aerospike was not significant, and Gary Hudson had already fixed the trouble with the spike's weight with his aero-plug design. There is room in the market for a metallic TPS lifting body flown off 1 or 2 SSME's or an aeroplug.

BTW, I've noted your preferred form of debating the issue is to deny the facts. Should you ever want to get at them, I suggest you research this issue over at NSF and find the thread where Gary Hudson himself chimes in and says they never solved all the problems with looking down from a tail sitter. You should know likewise that the LEM was nothing like a rocket, and that is was extremely dangerous to land. The LEM did not have to have a heat shield for entry, so there were plenty of places to put cameras. That's not true of any of the VTOL SSTO's we're here talking about. You're again mixing apples and oranges.

[Skipjack]

I'm surprised we're not seeing something closer to X-33 in the competition and have to wonder if L-M will step forward with one. The benefit from the aerospike was not significant, and Gary Hudson had already fixed the trouble with the spike's weight with his aero-plug design. There is room in the market for a metallic TPS lifting body flown off 1 or 2 SSME's or an aeroplug.

I do actually know Gary. He is one of my big heroes and he is actually the author of the article I posted earlier.
The aeropug is great, the main problem with the engine for the X-33 was that it was not only an aerospike, but also a linear aerospike, which was necessary due to the design of the vehicle (wide and flat). A bottom first reentering VTOL does not need an elaborate heatshield like the Venture Star, the Shuttle and the Dream Chaser need/would have needed.
This is one reason why I prefer bottom first VTOL. If you make RLVs, you want them to fly with as little maintenance as possible.

BTW, I've noted your preferred form of debating the issue is to deny the facts. Should you ever want to get at them, I suggest you research this issue over at NSF and find the thread where Gary Hudson himself chimes in and says they never solved all the problems with looking down from a tail sitter. You should know likewise that the LEM was nothing like a rocket, and that is was extremely dangerous to land. The LEM did not have to have a heat shield for entry, so there were plenty of places to put cameras. That's not true of any of the VTOL SSTO's we're here talking about. You're again mixing apples and oranges.

Why thank you. You are always so polite and kind and you definitely are full of facts in your arguments all the time...
Now getting back to the issues with landing a VTOL:
Gary and his teams never got far enough that they would have actually have to deal with this issue. I know that the Roton was a bitch to fly due to the bad view and the single rotor system. But I think that they could have made it work.
I also know that there are at least 4 companies working on VTOL designs right now (Masten, Armadillo, Blue Origin and SpaceX), some are suborbital (for now), but they all have the same problems to solve once they go to full altitude or (in the future) go orbital.
Armadillo and Masten have solved them successfully (seems like BO did so as well). SpaceX does not seem to be so concerned about it either. So the landing itself can't be such a huge problem.
You only need cameras looking down for the final approach. By then you dont need the heat shield anymore.
I could see them being hidden underneath a retractable part of the heathshield (just like a landing gear would be).
Or they could be attached to extendable landing legs (which would be protected during reentry as well.
I really cant imagine this to be such a huge problem compared to the many other issues that a RLV of any type is facing.
There are too many annoying people (SLS/Constellation/ATK fanboys) at NSF and so I stopped reading it.

[ladajo]

Tile maintenance is prohibitively expensive.

Yes, that does get your attention when you are standing in Orbiter Proccessing Facility with your hand on the vehicle. But the reality is the number of tiles replaced per mission was surprisingly small. I do not recall the specific numbers at this moment, but as I recall there were a significant percentage of tiles that remained in place over the lifetime of the vehicle. I think the bulk of the cost was in the inspection and analysis time for folks to "check the skin". The other drama was that each tile was completely unique in shape/size. In effect the worlds most expensive jigsaw puzzle. So each replaced tile outside of programmed replacements had to be made.

I always liked this Globe post up on a mission lifecycle...

http://www.boston.com/bigpicture/2008/1 ... avour.html

[ladajo]

I would like to clarify and say that the percentage of mission use replacements was low for the tiles. The tiles system itself has had some upgrades over the life cycle of the shuttle resulting in replacements for better materials.

Here is a NASA summary on the tile system:

http://science.ksc.nasa.gov/shuttle/tec ... s_sys.html

[ladajo]

Obviously you still don't get that what went up could come down. It is not a micro capsule parachuting in. It is a fully functional vehicle with massive payload bay that can take stuff up, and, BRING STUFF DOWN, in a controlled manner. Single use vehicles bring little things back, sometimes, and not always in a controlled manner.

You have not necessity to explain to me obvious things. Simply I say that if the program is stopped and USA still has demand to transport cargoes in space and back and also to do some manipulations there, Shuttle isn't so irreplaceable. And the preference is given to cheaper and safer solution.

Joseph, in case you haven't noticed, the Shuttle is being replaced by this:

http://www.boeing.com/Features/2012/06/ ... 19_12.html

And further mission sets will be picked up by follow on larger more capable versions that are coming very soon.

There are requirements for returnable flexible cargo capable vehicles. And this requirement continues to be met.

[Skipjack]

think the bulk of the cost was in the inspection and analysis time for folks to "check the skin". The other drama was that each tile was completely unique in shape/size. In effect the worlds most expensive jigsaw puzzle. So each replaced tile outside of programmed replacements had to be made.

Yepp, that is part of the problem. This is why even the much smaller Dream Chaser will have 2 months maintenance time inbetween flights. I find that quite excessive. The tiles also are weather sensitive.
I think it would have been better if SNC had opted for the other lifting body shape with sharp leading edges and using the metallic TPS instead.
I am also still confused about what happened with the research that went into the TPS for the X-33. It should be a lot tougher and should require a lot less maintenance. I was expecting them to use that for the DC. Instead they use the same tiles they used for the shuttle with the same problems.

I would like to clarify and say that the percentage of mission use replacements was low for the tiles. The tiles system itself has had some upgrades over the life cycle of the shuttle resulting in replacements for better materials.

Yeah, but it still was very maintenance intensive.

Joseph, in case you haven't noticed, the Shuttle is being replaced by this:

Well, we will see about that. Currently there are only two unmanned vehicles that are being used by the DOD exclusively. Boeing motivated by the commercial crew programe and the resulting boom in space development has beein toying with the idea of a larger X37C version. That currently has no funding though, AFAIK and is therefore still only a paper study.
I am not sure how maintenance intensive the vehicle is. I do believe it to be somewhat cheaper to operate than the shuttle. The reasons for this are in the much smaller size, the lack of complicated main engines, the slightly updated heatshield and so on. It will be interesting to see how competitive a X37C would be in a fully commercial market.

Personally, I favor VTOL designs because of the theoretically much lower maintenance times. This allows for a higher flight rate and that is key for the economics of an RLV.
A biconic vehicle also has the opportunity to make use of a magnethydrodynamic heatshield, something that I first thought off almost 20 years ago. The russians recently picked up the idea and there was meant to be a testflight of sorts, but I never heard of it again.
Using an MHD heathshield with a more complicated lifting body, or winged vehicle would probably not be feasible.

[GIThruster]

I think it would have been better if SNC had opted for the other lifting body shape with sharp leading edges and using the metallic TPS instead.

If changing the leading edge slightly enabled NASA to use TPS, they would have. The metallic TPS is only usable when the thermal loading is very low--like when you're flying the entire tank back in X-33. If that ship had used kerosene it would have needed tiles too.

[Skipjack]

If changing the leading edge slightly enabled NASA to use TPS, they would have. The metallic TPS is only usable when the thermal loading is very low--like when you're flying the entire tank back in X-33. If that ship had used kerosene it would have needed tiles too.

Good point about the higher bouancy of the Venture Star versus the Dream Chaser, which does slow down reentry speeds. There was however a NASA (IIRC) concept once with a vehicle simillar to the Dream Chaser that used sharp leading edges and a metallic TPS. I have to look it up.

[GIThruster]

Personally, I favor VTOL designs because of the theoretically much lower maintenance times.

There is another reason for spaceplanes. They're sexy. Think back to the 1950's and space art. . .no one was drawing capsules and even the rockets had enormous wings they landed on. People had been programmed to think in terms of wings for 3+ decades and especially highly swept wings.

I can recall when Paul and I collaborated on the Warpstar, he wanted wings for safety reasons and chose an existing airframe to simplify calculations. I was recommending what I called a "flying brick" because I wanted it to illustrate that there are no significant aerodynamic issues when you can produce constant thrust sufficient to lift from the planet. I'd have been thrilled for Warpstar to look like the Millenium Falcon.

If I were to recommend a shape for a first M-E Craft today, it wouldn't be for an entire craft. It would be for only a saucer shaped modular addition to MPCV, Dragon, CST-100, etc. There's little point in reinventing the wheel for an entire spacecraft, when these capsules share enough in common it's likely a single saucer section to could be added and make them interplanetary explorers. With 1N/w you could fly all these capsules direct off the planet to anywhere in our planetary system. Save nicer ships with conveniences like air locks and toilets for the next generation of bigger, better craft intended to live in for months or years at a time.