We need a new RLV - Moving beyond the shuttle

Ad Astra · 2003-02-02 09:35:46

Building a replacement for Columbia is not an option like it was back in 1986. As a nation and a member of the ISS coalition, the United States needs to move on. As part of the national recovery, and what will hopefully be a renewed emphasis on spaceflight, we must replace the shuttle at the earliest possible date.

I envision a three-pronged approach to doing so. First, DARPA increases funding for RASCAL, the responsive, reusable launch vehicle. The lessons and technology gained from RASCAL should be made open to the aerospace industry for incorporation into a new RLV.

NASA should financially support the X-Prize. Not directly, because that would violate the rules for the prize. But NASA can guarantee people and payloads that can be flown on board. For example, XCor plans on launching small satellites from its Xerus RLV. If NASA has suitable payloads, these small enterprises should be given the task of launching them.

Finally, we must proceed with Orbital Space Plane on an accelerated schedule. Issues such as booster safety and thermal protection that have plagued the Space Shuttle must be corrected in the process. Eventually, an unmanned RLV will be built to launch the OSP, finally giving us a fully-reusable vehicle.

We will remember the crew of the Columbia and carry on. Our astronauts must be given the best equipment for the dangerous tasks they undertake.

Adrian · 2003-02-02 09:49:51

Moved to Sci-Tech forum.

soph · 2003-02-02 11:01:08

I like a couple of ideas:

1) RBCC, i was told about this by mark s, this sounds like a very good idea.

2) an NTR SSTO. they can be made clean, and have a far greater mass ratio. they dont need as much fuel, and the fact that they can carry much more mass per total mass means better safety possibilities, including the heat shield.

3) the elevator. yes, its a decade or two away, but it is the ultimate SSTO in terms of cargo. we will always need a launch SSTO for crew and long distance passenger flights, etc.

4) OSP must be pushed!

Mark Friedenbach · 2003-02-02 11:40:32

3) the elevator. yes, its a decade or two away,

or three or four, or five.

soph · 2003-02-02 12:16:54

bah, not really. CNT research is going way up, and the improvements are amazing. that is the only real challenge to the elevator right now, besides funding. i think once CNTs are built in large quantities, funding won't be a problem. so 3-5 decades is really ignoring the true events that are going on.

Adrian · 2003-02-02 12:34:40

I'd be partial to seeing the DC-X revived; its initial trials went very well. In addition, turnaround time was an astonishing 26 hours, and it cost only something like $60 million to create the second working prototype. Not too shabby, and it didn't require the army of support staff that the Shuttle does.

Mark Friedenbach · 2003-02-02 13:41:21

soph: Carbon nanotubes could be mass produced within the next 15 years, but that's not half the problem. The CNT fibers would have to be delicatly woven together in order to provide the strength HighLift is talking about. That kind of positional control on such a large scale is more than decades away.

I'd be willing to debate this further, but perhaps we should move it to another thread.

Mark Friedenbach · 2003-02-02 13:50:47

As for the original topic, I think it's a fair bet NASA will follow through with their current plan. It seems wrong to say it, but a lot of good (political support and money) will come from this.

The shuttle program may be delayed, but it will not be canceled. Our international partners are relying on the shuttle fleet to deliver their modules to the ISS. NASA will get it's safety upgrades, as well as stronger tiles and redesigned insulation on the ET. And we can expect a spaceplane by 2011.

Ad Astra · 2003-02-02 21:09:32

I've been thinking about some features I'd like to see in a new RLV.

1) Extensive use of titanium. I'd like to see a titanium heat shield that is fixed to the airframe. This would require a re-entry profile that reduced thermal loads on the spacecraft. I was thinking that jet engines could be used to extend the cross range of the spacecraft. A lifting body would have less thermal loads, although it would be harder to control and structurally more difficult to build.

2) Encapsulated ejection seats. These would resemble the B-58 ad XB-70 ejection capsules. A clamshell would protect the astronaut and provide him or her with sufficient rations until the capsule could be recovered.

soph · 2003-02-02 21:19:31

1) aluminum is actually lighter, and what we use on our aircraft, but i dont know how it would hold up to atmospheric pressures. i believe titanium is one of the primary materials of the space shuttle.

2) NTR-based engines would solve any range and mass problems, by vastly improving the mass ratio. this would allow much safer systems, while still allowing much, much larger payloads with the same total mass.

Ad Astra · 2003-02-02 22:48:07

Titanium is marginally heavier than aluminum, but it's almost as strong as steel. In short, it has the best properties of both metals.

Another desirable quality of titanium is its heat resistance. I had to do a project about the collapse of the World Trade Center; in the process my team learned that the steel lost around 75% of its strength as a result of the elevated temperature. Obviously, temperature concerns should be a crucial consideration in designing the new RLV. Lockheed Martin originally planned on using a titanium skin instead of those infernal tiles to protect the Venture Star. I should hope that after the recent tragedy, we will give new thought to Lockheed's ideas.

Josh Cryer · 2003-02-04 09:51:54

Hmm, wouldn't it be better to just have tiles which were coated with a tungsten shell (this way they won't get damaged if something hits them)? The melting point of titanium is actually quite close to the reentry temperature. You have absolutely no room for error. And then, you have the issue of conductivity, if it's 1000C outside the Shuttle, how hot would it be inside? Tiles are mostly air, so that heat cannot get through, you would need some sort of insulation. So the only real solution is to coat the tiles with either titanium or tungstun (and I don't know about the latter, due to how heavy it is).

Ad Astra · 2003-02-04 11:08:46

I wouldn't recommend titanium for the heat shiled, but I would like to see some type of metal panels replace the ceramic tiles on future space vehicles. The orbital X-20 Dynasoar was supposed to have a Rene-41 steel structure, Molybdenum leading edges, and columbium skin with a zirconia nose cap. I think the Shuttle designers would have been wise to follow suit. I also think that the original shuttle could have been designed better if we'd have gained the experience by flying the X-20 during the 1960's.

dicktice · 2003-02-04 13:08:06

I like a couple of ideas:
1) RBCC, i was told about this by mark s, this sounds like a very good idea.
2) an NTR SSTO. they can be made clean, and have a far greater mass ratio. they dont need as much fuel, and the fact that they can carry much more mass per total mass means better safety possibilities, including the heat shield.
3) the elevator. yes, its a decade or two away, but it is the ultimate SSTO in terms of cargo. we will always need a launch SSTO for crew and long distance passenger flights, etc.
4) OSP must be pushed!

The elevator's a lifetime away--get real, and concentrate on what we can do in my lifetime, eh?

soph · 2003-02-04 20:45:52

well, since it will be done in your lifetime, i just did!

Josh Cryer · 2003-02-04 21:42:12

Hehehe, we may disagree on a lot of things, soph, but I like your enthusiasm about the elevator.

Personally, I was skeptical about the whole idea (KSR style elevators), but when I read Highlift Systems' design, I was quite thrilled. It's dooable. It's not a matter of if, but when.

Josh Cryer · 2003-02-04 23:40:23

Thought this was fitting for the current subject.

Some commentators have suggested that the Columbia disaster is more than a setback ? that it marks the end of the whole space shuttle program. Let's hope they're right.

I say this with regret. Like millions of other Americans, I dream of a day when humanity expands beyond Earth, and I'm still a sucker for well-told space travel stories ? I was furious when Fox canceled "Firefly." I also understand that many people feel we shouldn't retreat in the face of adversity. But the shuttle program didn't suddenly go wrong last weekend; in terms of its original mission, it was a failure from the get-go. Indeed, manned space flight in general has turned out to be a bust.

http://www.pkarchive.org/column/020403.html

Ad Astra · 2003-02-05 21:15:49

I'd like to see the shuttle retired, but I realize that it will not happen until ISS assembly is complete. I hope we will see that day soon, and the weary shuttles can be put to rest. Soyuz capsules will bring crews to ISS until Orbital Spaceplane is ready. I also believe that the shuttle will be brought back at the earliest possible date (within a year) and will not incorporate any susbstantial safety upgrades. Apparently the ISS schedule is the driving factor in NASA's decision making process. Let's hope that I'm wrong.

Phobos · 2003-02-05 22:44:10

soph: Carbon nanotubes could be mass produced within the next 15 years, but that's not half the problem. The CNT fibers would have to be delicatly woven together in order to provide the strength HighLift is talking about. That kind of positional control on such a large scale is more than decades away.
I'd be willing to debate this further, but perhaps we should move it to another thread.

It's not going to take decades to learn the best methods for weaving the cable together. Once we can create CNT fibers with the requisite strength needed for the tether (which could happen at any time) I strongly doubt if it will take eons to learn the best methods for constructing the ribbon. And it's likely a lot of other labs/colleges/companies that have nothing to do with the elevator will be working on similiar challenges since this technology could be employed in a wide range of applications here on Earth. Anyhow, Highlift is already fast at work on researching the best means of constructing the cable so they might have the problem largely solved before the CNTs are even mature enough to use. Visit their site and read about some of their research. I just don't share your pessimism.

Shaun Barrett · 2003-02-06 07:27:21

You tell 'em, Phobos!! :laugh:

I love your optimism and I love your enthusiasm! And I agree with you that huge steps towards a working space elevator could come quite quickly.

The tower might be the tricky bit, though. How high do they think it needs to be (was it 20 kms? ) and how much is it going to cost to build?
???

nirgal · 2003-02-06 09:50:57

There will be no tower. They plan to connect the cable to an oceangoing platform (modified oil-rig).

Josh Cryer · 2003-02-06 13:46:11

Or anywhere on the equator. Like I said before, expect companies to go to equatorial countries and try to petition the various governments to build the thing. A space elevator would be amazingly cheap once you had the ablity to mass produce the CNTs!

I'm with Phobos on this one.

Phobos · 2003-02-07 16:10:49

From what I gather, Highlift plans to build the elevator in international waters. I'm no expert on law when it comes to this sort of thing but I believe they won't have to petition any particular country for permission to build at sea but rather just get permission from whatever political body controls international waters (the UN?). Anyways thanks for the support Josh and Shaun, I tend to get passionate when somebody bad mouths the elevator. :laugh:

Shaun Barrett · 2003-02-07 18:30:28

Yeah, Phobos! It's nice to know I'm not the only one who goes purple in the face and gets blood-pressure about these pet subjects!!

About the tower thing: I must be confusing HighLift with some of the other ideas for an elevator.
Apparently, the diameter of the top end of the 'cable' has to be made greater (increasing its strength) in proportion to the length of the cable and in inverse proportion to its tensile strength.
With materials like steel etc., the diameter of the cable at GEO becomes totally impracticable - something in the kilometres range, from memory!
But, even with Carbon Nanotubes, increasing the length (a linear increase, obviously), increases the top-end diameter more than linearly. I don't recall the ratio with CNT, sorry!

Anyhow, the point is that building a tower as high as possible, to meet the cable as it 'grows' downwards, makes a big difference to how wide the cable needs to be at GEO.

I guess the people at HighLift have done the calculations and decided they can get away without any tower at all. And if they're happy, so am I!!

soph · 2003-02-07 21:43:17

no, the cable is thickest at the center, i believe. not at GEO, which is where the counterweight is.

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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Re: We need a new RLV - Moving beyond the shuttle

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