Gyrocopter rotor instead of canvas sail ?

Hi, this is a thought experiment or an idea for an RC project rather than than something that lends itself to full-size experimentation (who'd want to sit next to a large wind turbine for days on end ?); one of these morning thoughts that i couldn't plainly invalidate in the usual 10 minutes of googling. Cheers!

DISAMBIGUATION first: This is NOT about a wind turbine driving wheels or propellers through some kind of mechanical linkage. ( Such contraptions have been built to prove the counterintuitive points that it is possible to 'sail' directly upwind 'Sailing'?? Directly to Windward https://www.boatdesign.net/threads/sailing-directly-to-windward.27000/page-14#post-571266 , or go faster than the wind dead downwind https://phys.org/news/2010-06-wind-powered-car-faster.html )

QUESTION: Would it make sense (or has someone tried) to use a rotor in AUTOROTATION instead of a sail, for a sailboat or landyacht ?
(I mean a freewheeling lifting surface like in all these ultralight Gyrocopters: Autogyro - Wikipedia https://en.wikipedia.org/wiki/Autogyro etc )

POINTS that could be OF INTEREST:
- Lift/Drag ratio around 11: won't beat a wingsail, but much better than your usual canvas sail.
- Easy depowering: brake it and the lift vanishes. Windloads at rest are minimal, contrary to a flettner rotor, let alone a wingsail.
- Auto-limitation against overloads: Wingtips designed to stall in a storm are a common feature in large wind turbines.
- Mast height halved - a great match for freestanding masts, or A-frames from both sides of the rotor axis.
- Rig height at rest (aka bridge clearance) could also be halved using a two-blade rotor with a brake allowing to lock it horizontally, or a single-blade (yeah that exists, they use a counterweight. It's supposed to be the most efficient setup in theory), or these helicopter-style hinges allowing to fold away the blades.
- Massive wheel effect for roll and yaw stabilisation to help with comfort, but also system efficiency (steadier flow over the lifting surfaces).
- Reasonably simple mechanical system; there are probably more potential points of failure in a classic sail rig.
- Unlimited supply of free aerospace-grade blades, after their (few) approved hours before routine swap in helicopter rotors ...


If, against all odds, the idea turns out viable, some wind power manufacturer could try to scale it for the ominous unmanned cargo drone ships of the future. These companies' composites/cfd/hpc resources far exceed the means of the marine sector; getting them involved beyond their rather symbolic ocean racing commitments might bring a few nice surprises.

 

Sounds like an interesting experiment.

 

Interesting! The sailing upwind faces a tougher challenge on boats though, with electric you get something like 55% efficiency from input to propulsive power. Much worse than the one build in that video.

 

Found one!
AUTOGIRO BOATS - History 1870-1933 http://fionamsinclair.co.uk/yachts/auto/hist1.htm
There are a couple of windmill boats, then the third boat is exactly as you describe, built by/for Lord Brabazon only three years after the autogyro was invented.

 

Oh, cool !
So in 1933, King George V, who knew a lot about yachts, said "I have never seen a yacht sail so close to the wind". No videos found, but there is this tiny animated gif on Fiona Sinclair's site. The restored boat seems to live in the Cowes Classic Boat Museum - Wikipedia https://en.wikipedia.org/wiki/Classic_Boat_Museum now.

 

The rotor L/D will be closer to 8
Braking the rotor is not trivial. Braking faster than depowering a sail would require massive structure
Centripetal force stiffens the rotor. At stand still it will bend in high winds if not built massively or has provision to turn the tip path plane into the wind or to feather.
Changing the pitch of the tips to stall to prevent over speed is complicated. A feathering rotor will work but is complicated
Different relative wind speeds over parts of the rotor disc such as wind gradient or sail masking require blade articulation or massive structure similar to a wind turbine

 

Such a device wou[d be hard to reef if or when the situation demanded

 

No-one had their head chopped off yet by one ?

 

As opposed to having it smashed in by a boom during an unexpected jibe?

You "reef" it by feathering the blades. Like an airplane with an non-turning propeller. Turning them edge on to the wind so they produce minimal drag and thrust.

 

It does appear to be a "clear and present danger" in the one pictured.

 

Life is dangerous. Everybody dies from it.

 

Which doesn't mean you should hasten it !

 

Windmill Yachts have been around for nearly 100 years.
Here's a model


Then there is the Vertical Axis windmill, which avoids decapitation

or


But of course, the only mechanical sail that has ever found its way into commercial use, is the Flettner Rotor, which offers more performance overall, if not head into wind ability.
.

Or a combination of both


A long thread about it here
Windmill or Wind Turbine- powered boats: how many are out there, and are they viable? https://www.boatdesign.net/threads/windmill-or-wind-turbine-powered-boats-how-many-are-out-there-and-are-they-viable.14182/page-6#post-184637

 

Maybe one could use a wing in combination with this "Ion Drive". Something that uses electricity to charge and guide air ions across it's surface.

Maybe you could increase the lift from a flettner rotor without increasing drag.

 

I'd call it Samurai Sailing, LOOK OUT, or get your head chopped off !