Re: rutans roton, again

Spike Jones (
Thu, 07 Jan 1999 21:06:19 -0800

Steve VanSickle wrote: Atlas did not use liquid was
> Kerosene/Lox like the Roton is.

oops, yup, thanks steve. i was thinking of the upper stages that used lh2 and lox. i looked up those weights today and found the kerosene/lox info.

> > out of kerosene and lox with a 400 psi chamber pressure) i can
> > estimate (optimistically) drag coefficients and see if they really do
> I thought they were running at higher pressure than that, but I could be
> wrong. Even at higher pressure and aerospike altitude compensation, it
> will be a tough goal.

are they proposing the aerospike with roton? i didnt see it on the site, but it sounds like an ideal application. i was having trouble seeing how one could make a traditional nozzle stand up to the aero loading caused by the spinning.

> If 350 sec is an average for the whole flight,

well, not down low. thats surely their vacuum isp. i would be interested in the isp profile, given aerospike altitude compensation.

> 9300 m/s delta-v (which is a good estimate including drag and gravity
> losses)
> the mass ratio is 15 or so. Even if the averaged specific impulse drops
> to 320, the mass ratio stays under 20.

i was using 9500 delta v, but i will buy 9300. the mass ratio for the atlas is about 17, so if the rotoners can hit that, ill have some butts to kiss. on the other hand, the cross sectional area of the roton makes it more draggy, so im not sure a mass ratio of 17 will be sufficient. more on that later.

> The rotor blades will deploy upward before reentry (like an umbrella blown
> inside-out) and stay in the lee of the shock way, minimizing heating.

steve i remain skeptical on this scheme.

> > so cheap it would not be so critical to recover anything.
> Doubtful. True land that sucker, fuel it up, kick the tires and fly again
> reusability is the only way they will be able to take on the big boys.

well pardner, the old land, fuel and fly scenario is most probably not doable with single stage to orbit. its asking too much. but there are many interrim technologies, even with throwaway hardware that could stomp the big boys flat. our modern launchers all require standing armies at staggering costs. if we managed to get a design that is way simple, we could throw the stuff away every shot and *still* be waaay cheaper than a recoverable system that requires hundreds of full timers.

> I think Rotary will
> pull it off, if they have the financial ability to weather the loss of one
> or two vehicles during testing. A lot of "rocket scientists" will have a
> lot of explaining to do.

ya, ill be one of em. {8^D consider this tho: i have a version of a roton, been making sketches and calcs for a few months now. it is a two stage, both rotary, with no recoverables *but* it is verrry simple. given economies of scale, the parts could be mass produced and still beat up on the big boys. my version has lox/methane first stage and lox/hydrogen second. i am trying to calculate my way out of liquid hydrogen for the second stage, as it introduces so many handling difficulties, but i give away a lot of performance without it. i fear even my 9500 m/s delta v is a bit optimistic.

i tried to make it work with no despun section, but couldnt figure out how to guide the turn, so, i end up with a despun platform forward that holds the payload. problem im having is that the cross sectional area is large, so i lose an awful lot to drag. i wonder if i could get a mountain top launch site? a high one could get me out of half the atmosphere. the environmental types wouldnt like it tho. spike