5 ms·
I think you're overestimating how much fuel could be saved by this. You need 7.8 km/s of delta-v expenditure in any event because that's orbital velocity. Gen
by Symmetry 11y ago
I think you're overestimating how much fuel could be saved by this. You need 7.8 km/s of delta-v expenditure in any event because that's orbital velocity. Generally a rocket uses up 10.5 km/s of delta v to reach orbit with the difference being atmospheric and gravity drag[1]. So you'e got almost 3 km/s of delta v you could theoretically save here. You'd probably lose most of the atmospheric component but there's still the thrust you need to counteract gravity for however long it takes you to reach orbital velocity. The lack of air means you can safely accelerate a little faster but you're still limited by the weight of your engines and the heavier structure that faster acceleration requires. I'd put the reduction in needed delta-v at closer to 5% with a fuel reduction around 12%.
[1]https://en.wikipedia.org/wiki/Gravity_drag https://en.wikipedia.org/wiki/Gravity_drag
- vidarh 11y agoIt's not my estimate. I'm going by the claim in the article. EDIT: Which has now been replaced by the patent application, for the general confusion of everyone...
- andyjohnson0 11y agoI'm the OP and the link to the patent [1] is what I originally submitted. Nothing has been changed. [1] http://patft.uspto.gov/netacgi/nph-Parser?patentnumber=9085897 http://patft.uspto.gov/netacgi/nph-Parser?patentnumber=90858...
- Vendan 11y agoRide the elevator out to geosync, and you'd be in orbit for free. Ride it past there and let go, and you'd end up flying away from the earth. Time it right and you could end up traveling to the moon or to mars for little to no fuel costs, and just have to brake at your destination. Edit: My mistake, I didn't realize that this wasn't the normal concept of tether out past geosync.