If I was designing a "clean sheet" two-stage rocket/capsule system (and had the money, of course), I would go with LOX/HTPB or LOX/PBAN hybrid propulsion (or LOX/paraffin, if Space Propulsion Group's 10" LOX/paraffin hybrid is scalable to large sizes) for both stages. The launch vehicle would be completely safe to transport and handle on the ground, its exhaust would be very clean, its motors could be shut down in an emergency, and since its explosive potential (TNT equivalent) would be zero, the capsule's launch escape system would have much more modest performance requirements (just enough to keep the rocket from re-contacting the capsule after separation). Also:

The ISP of SPG's (Space Propulsion Group's) LOX/paraffin hybrid is close to that of a LOX/kerosene liquid propellant engine, so if it could be scaled up and/or clustered, this hybrid propellant combination might be the best. In addition to its high performance (which is due to the surface layer of the fuel melting to a liquid and mixing thoroughly with the LOX), the paraffin fuel grain's higher regression rate enables it to have a simple, cheaper-to-produce single cylindrical port. (Rubber-based hybrid fuel grains require complex, more expensive multi-port passages for the oxidizer, because their lower regression rates require more exposed fuel surface area for a given thrust level.)

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NAR #54895 SR

Very interesting! Jerry, if you could produce a small, cheap sounding rocket (say, 20 kg to 100 km, at least for a start) powered by one of your scalable hybrid motor designs, I have a possible payload customer for you. He noted in a public lecture in February that this year's sounding rocket campaign at the Poker Flat Research Range consisted of just *one* rocket, because suborbital vehicles are also getting increasingly expensive. He is passionate about reducing the costs of suborbital as well as orbital launches (he has flown microsatellites that successfully used cheap, non-aerospace rated components). If you are interested, I would be happy to send you his contact information.

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NAR #54895 SR

We can chat offline about that and we have also already been in contact. Thanks.

I beg to differ. Four fixed jets flowing at the same and constant rates would cancel each other out and have no effect upon the trajectory, except maybe to attempt to correct any asymmetry in the exhaust plume itself.


Bill

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You're right--they would result in neutral stability at best. But, an active system (with at minimum one gyroscope mounted perpendicular to the rocket's axis and connected to a valve for each jet) would keep the rocket flying in the direction it was launched.

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NAR #54895 SR

To sort of bring this thread back to where it started, at the SLI/USLI banquet the speaker was a former astronaut (I forgot his name) who works for ATK. The title on the last slide of his presentation was "Give me Liberty.....". A few of us sitting at the NAR range crew table just looked at each other and said "Or give me death?". I'm not sure that was the message they were trying to convey.

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That was Kent Rominger, the Liberty Business Development VP. A great guy who flew the shuttle FIVE times! He is a lot of fun to work and travel with. I am certain he would prefer death instead of being grounded permanently! <g>

Speaking of that, Kent did announce that they had selected the first crew to fly Liberty. I was truly surprised that he said he would not be on the first flight. I am sure he wanted to. I would not be surprised if he sneaks on a later flight. I do know that the commander for the first Liberty flight is an ex-NASA shuttle astronaut.

Matt

Small is not cheap. Big can be high value and lower cost per delivered mass. Rocketry uses a fixed pool of chemistry and mechanics and does not benefit much from the sizing and cost reductions electronics does. 95% of a rocket is the motor stuff and only 5% is the payload stuff.

One can cut their own throat and reduce profit margin to reduce price, or perhaps save on operational and non-vehicle costs, but even that is very hard to do within the many proscribed procedures NASA and FEDGOV have. As you have seen as a large civil rocketeer, the actual efforts and risks of flying rockets is small and trivial. It is all the procedural crapola NASA and FEDGOV adds that makes rocketry expensive.

Having fired 1" diameter motors and 18" diameter motors (and larger) I can tell you I was only 400 feet farther away for the 18" than the 1". I felt a whole bunch more at risk with the RRI GALCIT motors at Smoke Creek than I did the 18" hybrid at Mojave/Cantil. I was over a mile away from the GALCIT motors.

I would feel perfectly comfortable flying a 3 meter hybrid from Edwards to orbit. Even if it crashed and landed in a Landscatter housing tract, it would at most take out 2-3 houses. About the same as a Cessna.

This is well within mass-market business insurance limits, not special space insurance and treaty obligations measuring in several billions.

Jerry

He certainly was enthusiastic and his presentation was interesting but it seemed like a sales pitch. I don't think there was anybody in the room in the market to buy one. However, since ATK was paying for our meal and a bunch of other stuff he had my attention. My launch vehicle order will go to the first company that puts fins on their rocket.

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