Perhaps this has been covered before, but why not loop the ribbon so cars need not to be powered. Just lock them to the moving ribbon, power it from space and from the ground. One side of the ribbon is going up while the other side is going down. Slowly break rollers on the cars so they slowly pick up speed so there is no sudden jerk on lift-off. Maybe counter weights could come down to make lifting real heavy loads easier. I know it would require a ribbon twice as long but it would rid the cars of needing to be powered.

I'm not an engineer, just wondering.

wkinne

It is about time we built a model space elevator that uses an oscillating ribbon to raise the climber.  It only needs to be room size.  The ribbon could be piano wire or guitar string.

Hi A_M: I looked at the next future link, but most was unclear to me. Unless energy is added frequently, by accelerating the loop with a pulley at the Earth surface end, it is a perpetual motion machine = too good to be true. To over come gravity, air resistance and drag up the lifter and payload, requires the up going string to be pushed = compression. Small scale, a string like a long ago speedometer cable could do that, small scale = less than one kilometer is my guess. The pushed string would get very hot in Earth's atmosphere at more than about 1000 kilometers per hour. I suppose the string would decompress above earth's atmosphere increasing the speed slightly. Near the highest altitude, the push is changed to horizontal allowing a small portion of orbital speed in the desired direction to serve as the first stage to orbit. Re-entry of the string in the down portion, stretches the string increasing the speed, perhaps to the point that active or ablative cooling is necessary. Did I get any of that correct?   Neil

My solution was to add energy with a solar-powered station at some distance above geosynchronous orbit on the upward-bound leg of the loop.  It would in effect be climbing the ribbon (toward GEO) continuously and just at the appropriate speed to keep it motionless. A neat design, IMHO; solar cells, motors, rollers convert solar energy into mechanical energy in one simple step.

In my sketchy design, the anchor end was going through a big pulley at ground level, but was not being accelerated.  That allowed the pulley to consist of a film of compressed air with nothing actually touching the ribbon. The other end of the loop, far beyond GEO, didn't need a pulley or anything at all; the loop could just hang there, pulled outward by centrifugal force. I also described fairly tricky mechanisms for getting payloads on and off the ribbon at GEO and ground-level; not an easy task if the ribbon is moving at all fast.

No, no.  No taper at all. My design is a single loop, maybe 300,000 km of ribbon that all goes all the way around. So there's no part of it that's never under the maximum strain, and it can't be tapered.  This means it needs a very strong ribbon, maybe (probably) too strong to be possible.

Nonetheless, I occasionally consider gathering together all the parts of the Moving Ribbon design that I did in the spring of 2005 and making it into a coherent document. It had some neat ideas, including the perpetually-climbing power supply and a big rotating ring at GEO between the upward and downward parts of the loop. The hardest part, for which I never had a solution I was satisfied with, was getting on the ribbon at ground-level. You really have to accelerate to the speed of the ribbon (1000 kph) before grabbing onto it, and it's going straight up.

The moving ribbon seemed to me to be the only usable way to get people to GEO. At that speed it's only a 36-hour trip, so you get through the radiation belts with all due haste.