posted 09-29-2011 05:00 PM               

SpaceX plans first fully reusable launch vehicle

SpaceX CEO and CTO Elon Musk revealed Thursday his company's plans to try to build a fully reusable launch vehicle with the objective to exponentially lower the cost to orbit.

It's just a very tough engineering problem. I've come to the conclusion that it can be solved. And SpaceX is going to try to do it.

As previewed in a new video animation released by SpaceX today, the company's Falcon rocket first and second stages, along with their Dragon crew and cargo capsule, would use thrusters and engines to deorbit, reenter the atmosphere and each land vertically on land.

Now, we could fail. I'm not saying we are certain of success here, but we are going to try to do it. We have a design that on paper, doing the calculations, doing the simulations, it does work. Now we need to make sure those simulations and reality agree because generally, when they don't, reality wins.

Musk, who made the announcement at the National Press Club in Washington, DC, said that if they are successful, SpaceX's reusable rocket design would allow for "about a hundred-fold reduction in launch costs."

We will see if this works. But it is going to be certainly an exciting journey. And if it does work, it'll be pretty huge.

If you look at the cost of a Falcon 9... it's about $50 to $60 million. But the cost of the fuel and oxygen and so forth is only about $200,000. So obviously, if we can reuse the rocket, say, a thousand times, then that would make the capital cost of the rocket for launch only about $50,000.

posted 09-29-2011 06:00 PM               

A recovery system is nice, but it boils down to cost of refurbishment vs. cost of new booster. A recovery system is dead weight to the payload as the booster has to haul it up and that weight for the system and the propellant needed to fly it means the payload has to weigh less.

As for the recovery phase itself with active rocket propulsion, the DC-X project proved such a thing was possible, but it was also a more squat shape than a Falcon 9 first stage. I would liken it to balancing a pencil on one's finger while lowering it to the ground. A strong wind gust could send that thing toppling over rather easily.

The second stage might be the easiest one to develop a system for, given its size, but it will need a heat shield.

The Dragon capsule recovery to me bordered a bit on the absurd as for those motors (also used to control the launch abort system) to fire for that long requires a lot of fuel tankage (although the ATK Orion LAS abort test had motors firing for awhile as well at different thrust levels).

I see such a system as being possible, but only in combination with drogue and pilot parachutes for the initial slowdown from terminal free fall velocity (which slows down the deeper you get into the atmosphere) and the motors being used to control the last phase.

I would say it is an excellent idea to keep the main chutes as well since if ONE of these thruster clusters malfunctions, it is going to be a bad day for the cargo/crew inside. Plus, there is going to be a black zone as it were where the speeds are too slow for a secondary recovery chute system to work if a malfunction occurs with the capsule at low altitudes (say below 1000 feet).

The final bit that made me shake my head a little is having the rocket stages recover apparently at Canaveral on landing pads. The first stage would have to execute a turnaround of some sort to come back as it would be a bit far down range to pull that off (more fuel). Or would it somehow get high enough up to do a once around orbit and come back? The second stage I can see being capable, but not first stage.

But the range safety guys would have one heck of a field day monitoring those stages as they come down since if things don't go right in guidance, trajectory or propulsion, a rocket booster is likely to come down on a populated area. Recovery in Mojave I can see since it is so sparsely populated, but not Florida. At least not for quite a while assuming hardware gets built and tested.

posted 09-29-2011 06:07 PM               

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Originally posted by Jay Chladek:
This seems to have more of a fiction element than what can be done unless Musk gives SpaceX the funding to go carte blanche with this. I don't see NASA having the funding to pursue this.

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