rutans roton, again

Spike Jones (
Wed, 06 Jan 1999 22:00:44 -0800

>There are two reasons why the Roton can fly SSTO.
>First, the Roton is light. The Roton carries 24
>percent more propellant, but weighs only 5 percent
>more than an Atlas....

greg and other interested extropians, the above statement i pasted from the roton site

this is the critical statement on the whole site. my task, before i start buying roton stock, is in determining exactly what the comment means. if it means an empty roton is 5% heavier than an empty atlas, while holding 24% more fuel by mass (the only logical interpretation of the statement) well, then im impressed. i grant that it is possible, since a kerosene tank is much smaller and lighter than a tank that could hold an equal mass of liquid hydrogen.

next i must do the calcs. i have weights of the empty atlas, so from the info given, weight, size and specific thrust (i will assume they really did somehow figure out how to get 350 seconds vac isp out of kerosene and lox with a 400 psi chamber pressure) i can estimate (optimistically) drag coefficients and see if they really do have a chance of getting to orbit that way.

as for using an autogyro reentry system, i have gone even crazier trying to figure out how they could make that happen. every version of that i can imagine would be nowhere near handling the heat load of even a no-payload reentry. at best, i could imagine blades that would deploy very late in the reentry event, after going subsonic. this creates the need for a heatshield, which defeats most of the advantage of the autogyro system in the first place.

on the other hand, the system could perhaps be made so simple and cheap it would not be so critical to recover anything.

the whole exercise gives one a new respect for how deep a gravity well we are in down here. spike