Physics of wind sailing.

Let imagine that our boat have wind turbine installed on the mast
instead of sail.
Then turbine blades propel propeller in the water.


The question are:
1.What would happen if our vessel is directed exactly against wind ? Will it :
a) move forward against the wind?
or
b move back?

2.What is our boat sail down the wind's) boat can sail faster down wind then wind speed?
orb) boat can sail only below wind speed?

3>Boat travel perpendicular to the wind. ( at angle)
a) now our sail boat will travel faster then boat with just a sail, because beside propeller wind turbine working as sail there is additional propeller in the water to add extra force
or
b) normal sail performance will be better ?

For our theoretical consideration we could consider efficiency to be 100%.

Yes all depends on getting the gear ratio right. I recall we all discussed that downwind buggy on a treadmill years ago here on seabreeze. A bit embarrassing, we all got it wrong for a while, wrongly concluded that it was a youtube hoax. Easiest is just to realise there's not much difference, in concept anyway, of spiralling a foil through the air or water on the end of a propellor shaft or zig-zagging similar looking foils through the air and water with linked upwind/downwind tacking.

Efficient sailboats, AC75s and most likely kite foilers, can go up and downwind faster than the wind. I suppose you could say the AC75s have a fixed 1:1 gear ratio and have to choose the size of the sails and foils carefully to go fast. With a variable gear ratios and propellors you could pick a propellor size and and do the fine tuning with gear ratios.

The way kite foilers swing the kites through the air you could almost say it's like a big wind turbine

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Ian K said..
Yes all depends on getting the gear ratio right. I recall we all discussed that downwind buggy on a treadmill years ago here on seabreeze. A bit embarrassing, we all got it wrong for a while, wrongly concluded that it was a youtube hoax. Easiest is just to realise there's not much difference, in concept anyway, of spiralling a foil through the air or water on the end of a propellor shaft or zig-zagging similar looking foils through the air and water with linked upwind/downwind tacking.

Efficient sailboats, AC75s and most likely kite foilers, can go up and downwind faster than the wind. I suppose you could say the AC75s have a fixed 1:1 gear ratio and have to choose the size of the sails and foils carefully to go fast. With a variable gear ratios and propellors you could pick a propellor size and and do the fine tuning with gear ratios.

The way kite foilers swing the kites through the air you could almost say it's like a big wind turbine

Let's complicate our considerations a bit. For land or water vehicle powered by wind we can utilise that kinetic energy between those two media: water and air. Our sail, propeller or kite is just device to utilize that energy.

So let's imagine that we have now vehicle completely suspended in air. Airballon or airship. Can we have combination of propellers, sails or kites that allow our balloon fly directly up wind. (Or even any angle up wind at all?). The same in reverse. Can balloon now fly faster then wind down wind?

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Macroscien said..

Ian K said..
Yes all depends on getting the gear ratio right. I recall we all discussed that downwind buggy on a treadmill years ago here on seabreeze. A bit embarrassing, we all got it wrong for a while, wrongly concluded that it was a youtube hoax. Easiest is just to realise there's not much difference, in concept anyway, of spiralling a foil through the air or water on the end of a propellor shaft or zig-zagging similar looking foils through the air and water with linked upwind/downwind tacking.

Efficient sailboats, AC75s and most likely kite foilers, can go up and downwind faster than the wind. I suppose you could say the AC75s have a fixed 1:1 gear ratio and have to choose the size of the sails and foils carefully to go fast. With a variable gear ratios and propellors you could pick a propellor size and and do the fine tuning with gear ratios.

The way kite foilers swing the kites through the air you could almost say it's like a big wind turbine

Let's complicate our considerations a bit. For land or water vehicle powered by wind we can utilise that kinetic energy between those two media: water and air. Our sail, propeller or kite is just device to utilize that energy.

So let's imagine that we have now vehicle completely suspended in air. Airballon or airship. Can we have combination of propellers, sails or kites that allow our balloon fly directly up wind. (Or even any angle up wind at all?). The same in reverse. Can balloon now fly faster then wind down wind?

Sailing is essentially extracting energy from a discontinuity in velocity between two fluids. Generally that's air going one way and water in another direction. So to get energy from just air you need to take advantage of the wind profile. Albatross do this by soaring to height against the wind, wheeling around and gliding downwind using the height to gain speed, then with that speed wheel around and gain height again. Although heavier than air, they can soar indefinitely without flapping, but do end up downwind.

And there's ridge soaring, bouncing between the fast air going over the ridge and the still air below it. Like a ping pong ball between two bats. 548mph!

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cisco said..

All those videos remining me circus ,where magic happen.
Indeed , bunny pop up from the hat,
Everybody can see, nobody can complain.
I would rather ask to give $10,000 money back to professor Kasenko, as he was right anyway, at the end.All those famous physics experts fall the the same bunny from the hat magic trick.Hopefully our science experts are more curious in their Black Hole and Universe theories then trade mill experiment.

To verify treadmill experiment I propose two check two thinks.

1. They say stationery vehicle on treadmill?
Lets take off vehicle and run this conveyer belt alone then check the wind
at increments 1cm above, 2 cm , 3 , etc.
Near the surface wind speed will be equal to treadmill speed , quite high, then wind will be lower above and eventually not at all 1 meter above treadmill.so in may opinion that vehicle propellers us gradient, the difference in wind speed at heights.

If the same experiment will be in wind tunnel with laminar wind speed across whole propeller, I am afraid experiment will fail.
Another test could separate running conveyor belt from propeller by sheet with only small holes for wheel. this way wind created by running surface will not effect propeller blades. But unfortunately will effect surface of wheels a bit.
The guy should give the money back to professor.


2.Another trick is made clearly in catamaran movie. sailor is gaining speed across the wind then turning boat into wind,When point directly, boat will stall.So we can still claim that boat and cart can travel up wind directly buy not thanks to principles shown in those videos at all.