Re: SPACE: Roton in New Scientist

Michelle Jones (
Mon, 10 Aug 1998 23:06:47 -0700

Michael Lorrey wrote:

> >> mark the reason i am having such difficulty with this concept is that the
> >> roton is a re-entry system. you still have to lift the thing into orbit
> >> somehow to reenter the atmosphere. the reentry system of modern
> >> government launchers is neither the cost driver nor the weight driver. spike
> >The roton rotor blades are also used for launching as well.

michael, i should have been clearer in my explanation, but i was trying tokeep my response very short. when i saw the proposal that the roton was to use the blades to help launch, i thought the writer must be joking. my reasoning goes thus: if one tries to use the roton blades in the launch phase, one could at best get to an altitude of, well, what? 10 kilometers? our best helicopters cannot get as high as the highest peak, everest, less than 9 km. no chopper rescues possible for climbers there.

the key point is, if one starts at zero velocity at the outer edge atmosphere, surprisingly, one is
not appreciably closer to being in earth orbit than if one starts out
on the deck. this is
true. lets just say the lowest possible orbit is at 100 km, a verrrry short lived orbit. if
you somehow raise your spacecraft to 100 km without any forward motion, which is the case
if you went up with a helicopter, you have expended only about 3% of the energy required to
achieve orbit. i learned of this while evaluating the feasibility of carrying a rocket to great altitude
using a huge hydrogen balloon.
you fire the rocket from a 20 km altitude. turns out, the extra
altitude gains very little over starting on the ground.

> > In propulsion, it is always more efficient to move a lot
> >of mass a little, rather than a little mass a lot

right. however, rotary blade flight is not particularly efficient. one example ishuman powered flight. athletes have pedalled across the english channel, yet human powered hover is yet to be accomplished (last i heard anyway). i hate to be in the she'll-never-fly-orville crowd, but michael, i can assure you my friend, the roton will not fly. nooooo way. {8-[ spike