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I recently saw a demonstration of a flier based on the magnus effect. There is a good example on youtube here. How does the flying 'efficiency' compare to conventional designs?

When I say efficiency I'm not sure what the best measure is. Possibly lift to drag ratio? I'm interested in:

  • lifting capacity: how much weight could a magnus effect flier lift vs a helicopter or fixed wing design

  • energy efficiency

Obviously these things depend on many factors like size of the airfoil & airspeed so a rough guide would be sufficient.

There is a related question - what-are-the-advantages-of-a-spinning-wing-magnus-effect. This discusses practicalities but does not really cover the relative lift produced.

I also have the same question about cyclorotors, which I have posted separately.

Bruce Adams
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  • For the comparison to work, can you find and edit in a pure-magnus-effect aircraft and its mission (e.g. payload), so anyone wanting to answer, would use a comparable aircraft by mission? - From Review –  Oct 20 '21 at 11:44
  • One thing is for sure: after more than a century of fligh all together, and the magnus effect, cycloidial rotors and whatnot being of a ripe age also, they are not very efficient when considering practical use. Otherwise they would be used extensively. – Jpe61 Oct 20 '21 at 14:00
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    Solar and wind power were of a ripe old age without taking off not so long ago. I'm looking for a more physics based comparison. – Bruce Adams Oct 20 '21 at 18:44

1 Answers1

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"Were it not for the wind, flying would be so easy"

The root issue with any "high lift" design is cruising airspeed. The main advantage of commercial air travel is time savings.

Drag increases with V$^2$. As airspeed increases, drag from forward motion becomes much greater than drag from lift.

Airships (blimps or zeppelins) are most efficient at airspeeds up to around 80 knots. They made a serious bid for success in the 1930s before a number of weather related crashes swung sentiment in favor of mutiengined aircraft capable of speeds 3 to 4 times greater. These aircraft had a better safety record and were able to maintain schedules in more adverse conditions, critically, headwinds.

It is the cruise speed parameter, as efficient as possible, that one must design around. Modern aircraft simply fold their slats and flaps up to reduce drag at higher cruising speeds. What would a "Magnus flyer" do?

Secondly, the gyroscopic effects of a rapidly rotating cylinder wing in the roll or yaw plane (try this with a spinning bicycle wheel) would likely end the commercial scale-up effort before long.

Although a Magnus cylinder would increase lift coefficient, increases in weight and drag at higher speeds, plus stability issues would have to be overcome. In a world of biplanes, slats, flaps, slotted wings, blown wings, and helium, it is a non-starter.

Aside from gas, high aspect wings are most efficient for lifting. Golf balls don't have wings, so they use ... the Magnus effect.

Robert DiGiovanni
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  • Regarding the gryoscopic stability issue. I would have thought you counteract that easily with something counter rotating. – Bruce Adams Oct 22 '21 at 23:18