Helicopter on a turntable

Hole torn to 14th dimension, aliens invade through rift, aliens think we taste good, human becomes choice meat of the universe. End of life as we know it.

How about a hovercraft on top of a vacuum cleaner?

…with a Neil Sedaka album, three rubber bands, a paper clip, and a goat named Mavis.

Jet pack in a downward-flowing wind tunnel.

Hydrofoil in a fast-flowing river - optionally towing water skier.

Jet ski climbing a waterfall.

At first, I thought it wouldn’t take off. I mean, when a helicopter gets shot up and the tail gets busted in a movie (or in real life, I presume), it crashes because the body spins around the rotors and it can’t maintain lift.

After thinking about it for a while, I’d say there’s nothing wrong w/ the tail in your premise, so the tail holds the body in place while the rotors lift it off like normal. The result is a normal takeoff w/ some scraped and bent up skis.

The helicopter doesn’t take-off.

Two ways to look at it.

  1. Pure thought experiment.

For the purpose of studying what a helicopter does when its rotors are not moving relative to the surrounding air, there is sufficient skid/wheel friction to keep the helicopter rotating with the turntable and out of balance effects are ignored.

The helicopter doesn’t take-off because the rotor is effectively not moving. Helicopter may as well be stationary with the engine not running.

  1. Introduce some reality.

The tail rotor is operating normally and there is probably insufficient skid/wheel friction to keep the helicopter rotating with the turntable.

In this case the most likely result is that the helicopter crashes due to the competing forces of the rotating turntable, the friction on the skids and the tail-rotor.

Can we do a hovercraft on a vacuum cleaner next?

What if the helicopter was inside a wind vortex centered on the rotor? (i.e. mini-tornado) But of course, the turntable sits on a second turntable. And it’s turntables all the way down!

If a turntable is sitting on another turntable rotating in the opposite direction, will it play a recording of a helicopter taking off?