Citation X
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The X-33: Why Did It Fail?

Tue Aug 16, 2005 12:26 pm

What I understand is that the X-33 was supposed to replace the space shuttle with SSTO capability. However, suddenly funding for it stopped. Does anybody know why?
 
DfwRevolution
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RE: The X-33: Why Did It Fail?

Tue Aug 16, 2005 10:47 pm

Well, the X-33 was a 1/2 scale model of the "Venture Star," that would have replaced the Shuttle. The problems were numerous:

#1. Control issues. High-speed computer modeling showed the vehicle would have questionable stability during ascent and descent, prompting a redesign to add a pair of stubby wings. More $$

#2. Configuration. The original vehicle was to carry payload internally, much like the Space Shuttle does. For various reasons, Lockheed and NASA redesigned the vehicle to carry all payload in a large canister ontop of the vehicle. More $$

#3. Fuel tank design. Lockheed needed composite LH and LOX tanks to keep weight down, but composite tanks repeatidly failed in burst testing. This led Lockheed to an expensive redesign to aluminum tanks, at which point it was obvious the vehicle would have little hope of reaching its target altitude.


The first two problems led Lockheed/NASA into an expensive redesign each time. When the extermly critical tanks failed, it became clear that the X-33/Venture Star was ahead of its time.

I'm actually sort of glad the X-33/Venture Star didn't make it. Another LEO space craft isn't what we need, its time to start getting out there...
 
GDB
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RE: The X-33: Why Did It Fail?

Wed Aug 17, 2005 1:48 am

I agree with DFW, however, with hindsight, the MDD DC-X might have been a better, lower risk bet, as the basis of further development.
Even allowing for that test vehicle being pranged, (what testing is for).
 
Thorny
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RE: The X-33: Why Did It Fail?

Wed Aug 17, 2005 8:38 am

Quoting Citation X (Thread starter):
What I understand is that the X-33 was supposed to replace the space shuttle with SSTO capability. However, suddenly funding for it stopped. Does anybody know why?

In addition to DfwRevolution's points...

#4. NASA selected the most complicated, powerful, expensive, and technologicially risky of the three competiting X-33 designs. In retrospect, this was a spectacularly risky decision, and it should be no surprise that it failed. Boeing's Shuttle-like design was probably the simplest/safest, but it was also the least capable. McDonnell-Douglas's DC-Y design was somewhat more risky (powered landing) and would have led to a more powerful operational vehicle. Lockheed's VentureStar required new engine technology (aerospike), new fuel tank technology, a new Thermal Protection technology (metallic tiles), and a lifting-body design that proved unworkable.

#5. Lockheed-Martin had little motivation to succeed. It already had a lucrative contract with the government to sell and launch its giant Titan IV rockets. A successful VentureStar (the X-33 follow-on) would have cost them their own money to build and field, driven Titan IV out of business, and forced them to compete with Europe, Russia, etc. for commercial business to keep going. While LockMart certainly didn't deliberately sabotage X-33, they clearly didn't try all that hard to make it work, either.
 
Citation X
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RE: The X-33: Why Did It Fail?

Wed Aug 17, 2005 9:08 pm

Thanks for the info.

Well, I guess space travel is still a very difficult and expensive operation. I remember, there were 3 companies competing for the project namely Rockwell, McDonnell Douglas and Lockheed Martin.

Maybe with advancement in scramjet technology, the next sts would be more like an ordinary airplane.
 
DfwRevolution
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RE: The X-33: Why Did It Fail?

Thu Aug 18, 2005 2:00 am

>> Maybe with advancement in scramjet technology, the next sts would be more like an ordinary airplane.

For the time being, it would appear that NASA is moving for a quick retirement of the STS program, with the replacement being the CEV program. The CEV, for Crew Exploration Vehicle, will be a more Apollo-like capsule that will allow for trips outside LEO. We should see many CEV details in the next 6 months or so as NASA approaches selection of a vehicle contractor.

NASA has yet to precisely define what will launch the CEV, but it will likely be combinations of existing (or re-tooled) hardware. If you do some Google searches, you are bound to stumble upon some more information.
 
cloudy
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RE: The X-33: Why Did It Fail?

Thu Aug 18, 2005 2:20 am

Quoting Thorny (Reply 3):
NASA selected the most complicated, powerful, expensive, and technologicially risky of the three competiting X-33 designs. In retrospect, this was a spectacularly risky decision, and it should be no surprise that it failed. Boeing's Shuttle-like design was probably the simplest/safest, but it was also the least capable. McDonnell-Douglas's DC-Y design was somewhat more risky (powered landing) and would have led to a more powerful operational vehicle. Lockheed's VentureStar required new engine technology (aerospike), new fuel tank technology, a new Thermal Protection technology (metallic tiles), and a lifting-body design that proved unworkable.

I can understand why they would do that if the X-33 was to never have an operational successor. The way to advance technology is to try hard things. Its like building a concrete canoe. The craft will be almost useless, but the process of building it may teach you things nothing else will.

What blows my mind is that they actually wanted to build an operational vehicle (the Venturestar) having purposefully handicapped themselves by choosing the most difficult configuration. This would be like scalling up your concrete canoe design and taking it on a long treck through the Yukon. Not smart. When you actually want to DO SOMETHING with what you've built, you do things the easy way. Otherwise you will get a compromised craft. Its just common sense.

This behavior does not make sense to me, except through gross incompetence or simply a lack of any desire to actually do the task. My guess is it was a combination of both. At the highest levels this was a way for Congress and NASA to look like it was replacing the shuttle, without actually doing it.

Also, didn't Lockheed Martin put some of their own money into this project?
 
Thorny
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RE: The X-33: Why Did It Fail?

Thu Aug 18, 2005 7:24 am

Quoting Cloudy (Reply 6):
I can understand why they would do that if the X-33 was to never have an operational successor. The way to advance technology is to try hard things. Its like building a concrete canoe. The craft will be almost useless, but the process of building it may teach you things nothing else will.

Far more sensible, though, would have been a series of X-craft, one each to test the major new technologies needed for VentureStar. That way, Lockheed could have tested the aerospike engine on one vehicle, the metal TPS on another, and saved the difficult fuel tank for last. And they could have been testing two or three of the technologies concurrently, or at least have one of them airborne, instead of everything being at a standstill due to the composite fuel tank problems. Small steps instead of the giant leap X-33 required to succeed.

Quoting Cloudy (Reply 6):
Also, didn't Lockheed Martin put some of their own money into this project?

Yes, about half a billion dollars, or more or less the value of one Titan IV. X-33 was cancelled when more money was found to be needed to make it work. NASA said "no more money" and Lockheed abandoned the effort. That's a telling indicator of how little Lockheed wanted X-33 to succeed.

This may well have been the biggest taxpayer boondoggle of the 1990s.
 
bmacleod
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RE: The X-33: Why Did It Fail?

Wed Aug 24, 2005 10:59 pm

Rumor has it that the US Air Force is secretly going ahead with the X-33, but you'll have to get past security at Area 51 to find out...  talktothehand 
"What good are wings without the courage to fly?" - Atticus
 
ContinentalFan
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RE: The X-33: Why Did It Fail?

Thu Aug 25, 2005 1:53 am

Quoting Bmacleod (Reply 8):
Rumor has it that the US Air Force is secretly going ahead with the X-33, but you'll have to get past security at Area 51 to find out...

Well, it would be easy for the USAF, with all that alien technology hidden there and all. Maybe it's their cover for bringing out that alien technology... "We, uh, developed this right here... yeah, that's the ticket."  biggrin 

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