The linked Wikipedia page addresses turning the loop on and off. In fact, it can't be run continuously because it would overheat.
Edit: actually, I may be mistaken. Here is one of the relevant passages:
"When at rest, the loop is at ground level. The rotor is then accelerated up to speed. As the rotor speed increases, it curves to form an arc. The sheath forces it to follow a curve steeper than the rotor's natural ballistic curve, which [clarification needed] , in turn, exerts a centrifugal force on the sheath, holding it aloft. The loop would be anchored to the ground to remain at a fixed height.
"Once raised, the structure requires continuous power to overcome the energy dissipated. Additional energy would be needed to power any vehicles that are launched."
So is this talking about raising it only the first time? And then it has to have continuous power for the remainder of it's operational life? It seems like having power off capability shouldn't be an insurmountable task.
Edit: actually, I may be mistaken. Here is one of the relevant passages:
"When at rest, the loop is at ground level. The rotor is then accelerated up to speed. As the rotor speed increases, it curves to form an arc. The sheath forces it to follow a curve steeper than the rotor's natural ballistic curve, which [clarification needed] , in turn, exerts a centrifugal force on the sheath, holding it aloft. The loop would be anchored to the ground to remain at a fixed height.
"Once raised, the structure requires continuous power to overcome the energy dissipated. Additional energy would be needed to power any vehicles that are launched."
So is this talking about raising it only the first time? And then it has to have continuous power for the remainder of it's operational life? It seems like having power off capability shouldn't be an insurmountable task.