...or a dead end?

Clark Lindsey has a good survey of opinions on the utility of suborbital vehicles, in terms of their applicability to orbital space transports. Regular readers will know that I concur with Dan DeLong and Henry Spencer, and that I have little respect for the opinion of John Pike.

We're slowly recapitulating manned spaceflight the way it should have been done in the first place, had we not been derailed by Apollo.

It will be interesting to see what effects the winning of the X-Prize has on investor mentality. With the economy on the rebound, could this be the next "hot" speculative area for investment?

Not until an investor gets rich off it. But it's a good first step.

I had never heard of John Pike before, but his statement -

the idea that the X Prize will enable humanity to slip the surly bonds of Earth and get us closer to the human exploration of Mars is ridiculous.

shows an amazing amount of cynicism.

Flip over a rock and you'll find John Pike there. He's a professional opinion giver. He wears many hats. He's an "expert" on defence, an "expert" on space, and no doubt an expert in a dozen other fields.

I think this basically means he is a failure at the profession he went to school for--physics, IIRC.

Actually, he doesn't have a physics degree. In fact, he doesn't have a degree at all, but somehow he's made a lot of people think that he does. Not that one necessarily needs a degree to be a pundit, but in addition to lacking the formal education, he often says things that are outright wrong, but he remains in media rolodexes nonetheless, because he's good at soundbites and he tells lots of liberal journalists what they want to hear, even if it's wrong.

And to think I spent all that time to actually get me degree when I could have been a pundit without one.

Of course, I would probably not be very good at giving soundbites anyway.

Pike has been pontificating for a long time. He's been shown to be flat wrong repeatedly, and is happy to state opinion as hard fact, even on subjects that even those with a strong opinion will admit there is much doubt. Sure he says something real once in a while just to confuse everybody, but I try to ignore him as much as possible.

I'm hopeful about suborbital flight. I've had my hopes dashed too many times on earlier space projects to say it is a sure thing, but it makes a lot of sense: Most space technology goes back to the '60s with small evolutionary improvements. There are a lot of ideas about how to do things, but most haven't been tried because of the cost. Look at the X-prize contestants, most look like those old reels of wacky attempts at flight. Most won't work, others can't easily be adapted to orbital flight, but by golly, they are trying something NEW! And don't forget Tito - before him, space tourism had been talked about, but nobody took it really seriously. Even if that was a unique event, it changed attitudes.

Ultimately, somebody, somewhere is going to do it. There are a lot more countries getting into space now, and business is beginning to take it seriously. Back in the '60s, space was only really for military uses and national pride. There just weren't that many that could afford or had a reason to develop it. Today, there is more money, more technologically advanced nations, and more reasons to go to space. It may still take another couple of decades, hopefully less, but somebody is going to push things to the point where it accelerates on its own, and we go to space for real.

I can't help but think that Pike is correct. I just don't believe that traditional chemical rocket technology will do much to make space accessible. They're just too inefficient, expensive, and dangerous. I think we'll have to wait for technology like space elevators, lightships, etc to make space more accessible and profitable.

Ah, X. When you say chemical rockets are "too inefficient, expensive, and dangerous." you are making that conclusion based on vehicles that are flying now and have flown in the past. As far as efficiency, no launch vehicle has yet to employ the much more efficent "spike" engines that smaller test vehicles have already shown are practical (a la Garvey). As far as expensive, Elon Musk with his Falcon One is proving that Lock/Mart and Boeing's launcher prices are so high because they've essentially been building rockets the same old way with only incremental improvements since the 60's. Concerning safety, what about the new hybrid rocket motors from the likes of SpaceDev that it appears may actually be safer than modern jet airline engines? Your conclusion was correct before people started to think "outside of the box", but is true no longer!

Sorry everyone. I mistyped my URL in the above posting so that if you click my name it goes to the wrong site! This posting has the correct URL. Next time I'll check the link in the preview!

Otherwise, next time you mistype your URL make it a site we'll appreciate being misdirected to.

One reason I hope for significant incremental accomplishments by the X-Prize competitors on the symbolic date of December 17th is that I expect that in the distant future historians will look back from the stars and see NASA as being as anti-progress as Langley and the Smithsonian.

X: Of course, that's why nobody ever flies from the U.S. to Australia - too much fuel, and far too dangerous. Junking the plane after each flight, the thousands of people required to keep a single plane running, all make it impractical.

Seriously, take a look at the fuel requirements to travel that distance. Note that it isn't far different. Fuel costs are almost incidental. The real cost is in operations. As for safety, that depends on design. Planes are giant fuel tanks too, and to make a nice splash if handled badly (think 9/11). It is simply ridiculous to talk about safety or cost based on what we are currently using to get into space. CURRENT SPACE HARDWARE IS NOT DESIGNED FOR REGULAR SAFE USE.

I missed a word or two in the last note - Going to Australia from the U.S. requires nearly as much fuel as getting to orbit. Sure, there are differences, but technology and fuel costs are not the key problems with cheap space. Reliability and reuseable hardware (as opposed to rebuildable) are. Fuel efficiency is a relatively minor issue - it's the sort of thing you push for later, after you get a system working. Note that the Shuttle has high pressure pumps and engines that are quite efficient - and have to be rebuilt after each flight. Exactly the sort of thing you DO NOT want on such a craft. Compare to the reliable RL-10.

Fuel efficiency is a pretty big issue if you want to build a reliable single stage to orbit vehicle. The less efficient the engine is, the lower the mass fraction of the vehicle can be. And the lower the mass fraction of the vehicle is, the lower the factors of safety for the vehicle can be.

The takeoff weight of a 747 is only about 41% fuel, but even with engines as efficient as the SSME, an SSTO would need to be at least 85% fuel. If this number could be brought down with more efficient engines, you could build a more robust vehicle that in turn would reduce the operational costs of the vehicle.

If you assume that 5% of a vehicles mass would be used for payload, that only leaves 10% of the mass for the entire vehicle. Don?t underestimate how difficult it is to build a robust, reliable vehicle with these kinds of mass fractions.

X, did you even read what I wrote in my earlier response to you? Take my line "As far as expensive, Elon Musk with his Falcon One is proving that Lock/Mart and Boeing's launcher prices are so high because they've essentially been building rockets the same old way with only incremental improvements since the 60's." The first of Falcon One's two stages is fully reusable and requires a very small crew doing turn-around maintenance; therefore, your comment "Junking the plane after each flight, the thousands of people required to keep a single plane running, all make it impractical." does not apply! The first of these rockets has already been built and is due to launch a satellite for the U.S. Defense Department in March, 2004. By the way, Musk and his colleagues at SpaceX are working on making the second stage reusable as well.

One thing I didn't mention in regards to the hybrid rocket engine from SpaceDev that makes its so much safer is its nonvolatile fuel. I don't know if you've ever tried to burn rubber before, but it is not prone to fast uncontrollable combustion. Consequently, a violent explosion is essentially out of the question with this engine even when the fuel is in the presence of its oxidizer (in this case nitric acid). This engine is the one that Burt Rutan is going to use in his Space Ship One X-Prize contender.

To sum up, All of your comments are relevant only to the old style "ballistic missile" launch vehicles currently being sold by the big aerospace companies.

A minor correction to my above post. The oxidizer in the SpaceDev hybrid is nitrous oxide not nitric acid.

I read your posts Rick, I agree that maybe I jumped the gun on saying chemical rockets are hopeless. I just hope the gov't doesn't screw everything up with draconian regulation and lets these experimental rocket engines be used.

Rick Boozer wrote:
>One thing I didn't mention in regards to the
>hybrid rocket engine from SpaceDev that makes
>its so much safer is its nonvolatile fuel. I
>don't know if you've ever tried to burn rubber
>before, but it is not prone to fast
>uncontrollable combustion.

Speaking of 'non-volitile' fuel, have you been keeping track of the 'newest' hybrid fuel?

Paraffin... ie: Candle Wax. Tests by Stanford/NASA so far are showing it's @ 3 times better than the standard 'rubber' fuel, and even safer to use.

Still waiting on further scale up tests though.

Randy

Rick, you might also want to do a little reading. The ?junking the plane? bit was mine, a satirical comment to X (note that the sentence starts with ?X:? and the next sentence starts with ?Seriously?? ). In an earlier posting before yours, I had also made the point that most space technology dates back to the ?60. The key issue, of course, is that we don?t run airlines at all like space launches because it would be far too costly and dangerous. And it is ludicrous to make decisions on space flight based on the hardware and procedures we are using now.

Rocketman: On fuel efficiency - yes, if you want SSTO, then you need very good fuel efficiency. But, who was talking about SSTO?

To make SSTO work, you really need to push the envelope on design ? composite everything, aerospike/variable geometry engines, etc. etc. Pushing the technology is a very good way to end up with a white elephant, with hardware constantly requiring repair and low safety margins. In theory, an SSTO could be cheaper to run than a multi-stage, but not if it requires constant attention to keep it operational.

I?d much rather see a two stage system with a reusable first stage, with a design focus of: Make it work reliably, if it fails make it fail safely, when it breaks make it easy to fix, and after you?ve done that, incrementally improve the design for efficiency.

In the long run, I?m betting an SSTO using scramjets or at least some method for using air for part of the flight will be the way to go, but I don?t think we?re there yet.

VR wrote:
>In the long run, I?m betting an SSTO using
>scramjets or at least some method for using air
>for part of the flight will be the way to go,
>but I don?t think we?re there yet.

Actually we are. We don't even need scramjets. Ramjet engines have been run up to Mach 8 using conventional hydrocarbon avaition fuels. DARPA has dusted off the work that NASA/DoD did in the late 50s for mass-injected/activily cooled, high performance turbo-jet engines and is applying it to modern high-performance turbo-fans. They say they can get an engine up to Mach 6 and keep it there. (The airframe is another matter :o)

So it's not a matter on waiting on the 'right' engine as much as putting what we have together in a package that works, is cheap to operate and in-expensive to build.

Randy