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Discussion: Rocketcards and the X PRIZE CUP

Posted by: The Legionnaire - Wed May 12, 2004 12:49 am
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Discussion: Rocketcards and the X PRIZE CUP 
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Space Walker
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Post Discussion: Rocketcards and the X PRIZE CUP   Posted on: Wed May 12, 2004 12:49 am
Hi everyone,

In the past few weeks there has been a lot of discussion about rocket cars versus rocket spacecraft, and the relative virtues of each. The discussion has become quite heated, to say the least. Although the moderators do not condone such behavior, we do favor the freedom of speech and the dissemination of ideas, so we will allow discussion of rocketcars to continue. Please make all new rocket-car related postings under this thread, as well as under the other two threads "Discussion: Rocketcars and the X PRIZE," and "Discussion: Rocketcars and Historical Examples."

Thank you.


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Space Walker
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Post    Posted on: Wed May 12, 2004 12:53 am
To start this forum off, here are a few relevant posts that I took from an earlier discussion about the X PRIZE cup and rocketcars.

The rocket propulsion technology will still advance whether the motors going horizontal or vertical, but for spectators (in person or on TV) the events will actually be exciting to watch. Formats could include drag races, who after several runs could come closest to consistently running a given target speed at a given distance, and/or standing start records.

For examples of what the vehicles could be like go to:

http://www.iit.edu/~iit100/

http://www.americanjetcars.com/bonneville/bonngia1.htm

http://www.americanjetcars.com/bonneville/bonvil1.htm

http://www.sonicwind.com/page1.html

http://www.sonicwind.com/constpage1.html



IMHO, there comes a point at which wheeled vehicles add negligable development to the role of suborbital spacecraft. IIRC, the rocket drag cars of the 70's were all peroxide monoprops, and a lot of good work was done on them by folks like Ky Michaelson, so probably a lot of debt is owed to their work (and risk). But cars are cars, and spaceships are spaceships.

For starters a wheeled rocket car would have to be built far more robust operating at the same speeds that an x-prize class vehicle would typically hit max-q (Mach 3 to Mach 4). And if their engines are not being built with those thrust levels in mind, then they aren't of much help at all. Stick a rocket drag car upright and put fins on it and see how high you get. . I think it's reasonable to say that most X-prize craft are theoretically safer then a supersonic land-speed record car, even in their respective environments. There were some pretty horrific NHRA deaths in the rocket drag racing period.

Also people need to be looking up, rather then down. The idea is to get potential customers interested in space tourism. A redux of Blue Flame and the Bud Rocket won't accomplish that. Xprize can. I am not trying to put down rocket drag racing. If it werent for the shortage of peroxoide back at the end of its heyday, there's no telling where it would be now. But even then, it would probably be an also-ran to sports, alongside Reno pylon racing. Who knows, maybe the Xprize will help make it easier for future rocketcar builders to get ahold of fuel. Maybe they'll be buying their engines premade from ARCA one day. In that regard, rocketcars might have a positive effect on the suborbital industry, though it wouldn't be something to base a business model on.

Finally, there's no reason to assume that the Xcup would be unexciting to watch. The audience would be different from NHRA events, but interested nonetheless. People were interested in the Schneider trophy once, too.



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You went on (and on) at length about something (the car chassi) that is pretty much completely irrelevant to the rocket motor itself.

Like I said, rocket motors DON'T CARE whether they're going horizontal or vertical. You STILL have to engineer in THROTTLEABILITY, RELIABILITY, etc.

The Blue Flame biproellant land speed record car came BEFORE the rocket dragsters and remains the most powerful and sophisticated private manned liquid propellant rocket constructed to date.

Want to see some DEMANDING propulsion system problem? Here's some good ones. A rocket car that could accelerate to 500 mph in the quarter without blacking out the driver (it's doable) or a rocket car that could accelerate to supersonic speed in a distance of one mile.


The Blue Flame could go from having just been run to being fully prepped and ready to run again in 45 minutes. Is there ANY X Prize competitor who approaches that?


Why bother with rocketcar engines when Xprize teams are already developing far more capable engines for their own uses? Not to mention, suborbital is only part of the answer. In any case, there's more to an, rlv then the motor.

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Rocketcar engines are not as powerful, and cannot be as powerful, as Xprize engines, unless you are clustering them in the rlv.

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The Blue Flame had an initial design thrust of 13,000 lbs with provisions to uprate it to 22,000 lbs thrust.

"cannot be as powerful, as Xprize engines"? What kind of sense does that make? Where did you get the idea there's some sort of upper limit to the size motor you can put in a rocket car?

A rocket car chassis is much less expensive to develop and build than a flight worthy airframe, while at the same time requiring the same level of propulsion system sophistication found in many X-Prize entries.

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I'm not the one who can't make the connections. Anyone who shows they can SAFELY and REPEATEDLY propel a rocket car to speeds of 300 mph, 400 mph, or supersonic has just demonstrated (whether or not they've built or flown an airframe) they can engineer a complete propulsion system with the level of power and sophistication required for an X-Prize vehicle.


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Uh, yeah, okay... So now you've got a rocket motor that can produce huge amounts of power over an extremely short period of time... Where I come from, that's called the thing in the ass end of a dumbfire rocket -- the kind you launch from an A-10.

For a space vehicle, you need an engine that can produce large amounts of thrust over a very long period of time (comparatively).

Not to mention an airframe and stabilizers and thermal shielding and all kinds of other little things that make it go up and come back down in one piece -- that rocket-powered cars don't deal with.

In short, it doesn't work. They have some common ground, but it's extremely limited, and will not help the field of space development much, if at all.
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The BIPROPELLANT THROTTLEABLE 13,000 lbs thrust Blue Flame land speed record car could go from having just run to being ready to run again in 45 minutes. This process included repacking the chutes, refilling the hydrogen peroxide and liquid natural gas tanks, and recharging the helium bottles. Are there any X-Prize vehicles which can claim that sort of turnaround capability?

Besides having a rocket motor and propulsion system designed to last the lifetime of the vehicle, many of the drag racing rocket cars had a motor developing as much thrust as a shuttle OMS engine.


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