3 of these wires anchored to one spot, and constant pull upward would prevent the rope from bending down, and would save much energy.

The structure relies only on tensility and would collapse without being continuously pulled up. But still, only a tiny rocket is then needed to send the last stage into space.

Next rockets reach the wire top independently, and reuse it.
-- pashute, Jan 30 2017

Launch loop https://en.wikipedia.org/wiki/Launch_loop
mentioned in my anno [notexactly, Feb 26 2017]

My idea's better. See anno https://www.youtube...watch?v=J1MAg0UAAHg
notexactly's Launch Loop link explained in a video [pashute, Jan 25 2018]

@pashute,
If the wire was wrapped around a helium-filled tube to make it weightless, it wouldn't need the planes. [+]
-- Alvin, Jan 30 2017


If the wire was instead a looped iron pipe of diameter ~50 mm and length ~4 Mm, half of which was covered by another slightly wider non-ferrous pipe, that half of which was arched up to ~80 km above ground, and the other half of which was at ground level, and the entirety of which was pushed along at ~14 km/s by a station at each end, it wouldn't need the planes. It also wouldn't need the rocket until apogee (for circularization/perigee raising). [link]
-- notexactly, Feb 26 2017


This idea is better than a launch loop, since it uses tension only, and no length structure. So until some height you would be using much cheaper airlift technology (or even LTA) and once at the top you have a triangular tether to pull you out.
-- pashute, Jan 25 2018


This seems promising but it's a little unclear. Are the 3 wires almost vertical? Can electric planes fly that high? Do they use propellers, or electrically heated jet turbines, or ion wind thrusters, or something else?

Or are there 3 107 km wires at the top forming a triangle, and 3 more connecting the corners of the triangle to a common anchor on earth? In which case they're still pretty high, and can they still fly?

A related idea: Have something the shape of a launch loop, but instead of super fast wire holding it up, have a series of electric planes tethered very closely to it to hold it up. Or maybe attached like a maglev train. They fly along it from one end to the other.

They definitely need their wings, to generate lift. They might not need steering, they can be attached to the loop for that. Or maybe it would help stabilise things. And they might not need a propeller, maybe they can pull forward on the loop, I'm not sure.

The maglev has a second track, for payloads to be shot into orbit (which need to go much faster than the planes). The top of the loop has a lower pressure atmosphere, hopefully enough to support the plane but not enough to obstruct the payload.
-- caspian, Oct 29 2018


I read that the SR-71 Blackbird can reach altitudes over 90,000 feet when fuel is low. That may be as much as we can do with a jet engine, so something else is needed.
-- caspian, Oct 30 2018


A better reference point than the SR-71 is the Helios solar electric plane. That sustained fight over 96000 feet for 40 minutes. Of course that's not 107km, and it wasn't trying to hold up a very long tether.
-- scad mientist, Oct 31 2018



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