Re: rutans roton, again

Spike Jones (
Fri, 08 Jan 1999 23:09:29 -0800

Steve VanSickle wrote: ... and are relying heavily on hypersonic rotor wind tunnel work that NASA did in the 60's. Amazing all the stuff gathering dust in their libraries.

ive seen a good collection of that material steve, and yes, it is amazing some of the experiments that were done.

> But I'm not sure you would get a fair contest. ... Don't get me wrong,
> I'm not talking secret conspiracies...just good old fashioned hardball.

dan goldin seems to have a great attitude toward maveric rocket builders. hes a good man methinks. as for lockheed and boeing, well, it could be worse: at least its not microsoft.

> >> A lot of "rocket scientists" will have a lot of explaining to do.
> >
> > ya, ill be one of em.

but this is one time when i hope i am wrong. ill be quite pleased if the ssto roton guys make a fool of me. {8^D or any ssto for that matter. (im betting against lockheeds own ssto for becoming a *practical* ssto, altho i am hopeful the skunk works guys can pull off another miracle.)

> But doesn't the concept more or less require the fuel and oxydizer to be
> closely matched in density?

it helps greatlyif they are. the spin rate is determined by the less dense fuel, so one would need to drop the pressure of the denser lox across a regulator of some sort. i have given up hydrogen as hopeless for this reason: the low density requires spinning almost 3 times faster with hydrogen as you would with kerosene. (the spin rate varies as the inverse square root of the density of the fuel, all else equal).

> Is it because the low denity fuel requires a large diameter?

no, its because if one goes with the "spin tanks and all" scenario, one must arrange for the moment of inertia about the spin axis to be greater than the moment of inertia about the other two orthogonal axes, this for max stability. unfortunately, this causes you to have a lot of area to push thru the wind. this might cause the tanks-and-all notion to be impractical. {8-[

> And I would think that
> rotating the feul tanks are more trouble than they are worth...

im starting to think you are right, but i have one more round of calcs to do first. i might have become too infatuated with the notion of a launcher with almost no moving parts. my last scenario has a spherical lox tank with tow torroidal ethane tanks around it.

> ...slow, low pressure rotating seals aren't *that* hard.

i have an idea for rotating seals, now that you mention it, that use laminar flow compressed air at the dynamic interface. if i convince myself completely that the tanks-and-all notion is hopeless, perhaps i will look into that. spike