Imagine a hot air balloon with a basket suspended from it using a low friction bearing.
Inside the balloon a number of radio controlled vehicles are driving at speed in horizontal circles on the inside surface.
The vehicles all go in the same direction and cause the balloon to rotate about its vertical axis, whilst leaving the basket not turning.
If there is wind blowing across the spinning balloon, the Magnus effect will generate a lift force roughly at right angles to the wind. This would allow the balloon to be steered, just as sailing boats are, rather than just bobbling about at the mercy of the elements.
(My calculations show that, for a wind speed of 2ms^-1, balloon rotation rate of 1 turn per 2 sec (perhaps too fast) and a balloon radius of 5m, the total lift force generated would be about 1.2 kN per unit height of the balloon. For a 10m tall balloon, this gives 12kN, which would be reasonably significant compared to the (approximately calculated using Cd=0.9) drag force of approximately 200N at the same speed.
