The Flettner-rotor: "How to build an airplane without wings."

[DetlefK]

Flettner-rotors are based on the Magnus-effect: When wind flows around the cylinder, the rotation of the cylinder creates increased air-pressure on one side and lowered air-pressure on the other side. The pressure-differential pushes the cylinder in a direction vertical to the wind.



I would LOVE to know the energy-efficiency on air-travel for that one.

It has been estimated that a "sailing"-ship with Flettner-rotors has 50% less fuel-consumption than a freighter using propellers.

[Timewas]

1. That is neat

But looks like adding more moving parts that can fail...wings work pretty good.

[James48]

2. I would like to learn more about this.

Very interesting.

I wonder how it would scale up.

[ROB-ROX]

3. WONDERFUL

These two videos demonstrate the effects of progressive thinking to expand and improve aviation. I wonder why the good old boys have not followed up on these innovations versus looking for the big bucks? Only in the future will know if these innovations will be utilized by the aviation industry to improve a stagnate industry stuck in the last century..........

[caraher]

4. The energy efficiency is probably quite terrible

It takes energy to spin the rotors vs. no energy (beyond fabrication) to have an ordinary wing, and you separately need a propulsion system.

That's a bit different from a sailing vessel. Here you need lift to keep the plane flying, while buoyancy holds the ship up. The comparison with the freighter is between two very different means of propulsion, while here it's between two means of generating lift.

From back when I was an aerospace engineering major I remember a textbook problem that was something like, "Imagine replacing the wing of a 747 with an equally long broom handle. How many RPM would you need it to spin to create the same amount of lift?"