Any ideas on how to change the length of an endless rope drive during flight?

[Windy_Skies]

@Windy_Skies

Another idea would be to now add an extra drum next to the loop, rotating at the same speed as the tether, with now an extra arm adding wraps around this drum, like how you would reel in a kite by using one hand to wrap the line around a drum in your other hand. This would work I think, for short lengths. This extra drum could also replace the ground station pulley.

A random video showing a spinning reel on a fishing rod

Adapting this to the proposed system is left as an exercise for the reader for now. The goal would be reducing the number of bends the tether has to go through and deciding if you want to align the drum along the minor or the major axis of the rope drive to achieve this. The rotor wrapping and unwrapping one end of the tether on the drum would need to not interfere with the other end of the tether leaving the drum.

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@PierreB

I don’t know how this would work, but an idea inspired by this idea inspired by my idea:

Now you have the two drums like sketched, the tether comes from the airborne pulley, it wraps around one drum a number of times, goes through a tether tensioning device connected to this drum, then some distance to a tether tensioning device attached to the other drum, wraps around that drum a number of times, and again goes to the airborne pulley.

Lengthening and shortening the rope drive is now done by varying the relative speeds of the drums. If it is shortened, the tether winds up laying on the ground or in a bucket between the two tether tensioning devices.

This is the start of an idea. I don’t know if letting the tether lay on the ground or sit in a bucket is a good idea or what other ideas there might be.