Downwind faster than the wind -- theoretical limits?

[The_Hamster_King]

@Chronos

Oddly, it got a lot easier, conceptually, for me to understand the concept when I stopped thinking of it as moving relative to the ground in the same direction as the air, and started instead thinking of it as moving relative to the air in the opposite direction as the ground.

The way I got it was to imagine a low-flying zeppelin powering its propeller by lowering a wheel to touch the ground below. It made more sense once I stopped thinking of the wheels as anything other than a power source for the prop.