'Sailing'?? Directly to Windward

Note, I have drawn 2 sketches to accompany this post, unfortunately I am having scanner problems. Will add when the scanner works. Sketch A is a 4 wheeled platform with a similar turbine arrangement to Windmaster’s driving 2 of the wheels. Sketch B is like Windmaster’s model boat.

The factors that allow the car or boat to move into the wind are

1. The lift/drag ratio of the turbine blades
2. The ground or dense water to push against.

A turbine blade works on the same principle as an aircraft wing.

Aircraft wings can achieve remarkable lift/drag ratios.
A glider can have a ratio of 70:1, even a Boeing 747 is 17:1 and a hang glider 15:1 and this is including the whole aircraft, not just the wings.

See tables near the bottom of this link http://en.wikipedia.org/wiki/Lift-to-drag_ratio

So a turbine blade is like a wing but is twisted because its tip moves faster than at the hub.

The essential point is that the forces causing it to rotate are much bigger than the forces pushing it backwards.

This would still be the case in Windmaster’s latest model which has flat blades.

Starting with the car, sketch A.

The forces acting on the car to move it down wind are the drag due to the windage of the vehicle plus the drag of the turbine.
The turbine creates a torque this is transferred to the driven wheels.
The torque at the wheels will depend on the gearing and in turn the force applied to the ground will be the torque at the wheels divided by the radius of the wheel.

As the total wind drag + friction in the mechanism is small relative to the torque generated, it is bound to move upwind, given a sensible design.

The boat, sketch B, works on the same principle but the driving wheels are replaced by a propeller.

The formula is correct, it is the way it is applied which causes the problem.

The power of a turbine is its torque x its angular velocity. It is not a 'drag' force times the wind speed.

 

I really think the disconnect is not in the idea that the drag of turbine wouldn't qualify but in practical way the propellers work.

you could do the whole apparatus with mechanical gears (so that even water and wind would be represented by rack and pinion style setups). In that kind of setup either the cart would be forced to go forward when ever the "wind" rack was moving as it wouldn't allow slip like propeller does. thus a situation like your exampel of 5mph wind but zero boat speed would not be possible EXCEPT if you had perfect variable ratio transmission and in that case the torque in fact would indeed be infinite.

P=FV works as I suggested assuming 100% efficient props - at 0 speed the propeller in the water is being 0% efficient.

Of course the drag to lift ratios etc. give you more realistic idea of real world losses but the fundamental idea from where does the energy come form is exactly the same.

 

Some of the confusion I have with your concept arises from the different speeds/velocities and expressions used.
To go through your posts

Could you define what you mean by "turbine drag"

The power at the turbine is its torque x its angular velocity.

I can not see how the speed of the boat through the water regulates the size of the force transferred, that would depend on the propeller pitch, diameter, rpm etc.

not excess power as it is still 100w

This is the requirement for sailing that the wind is moving relative to the water. If you have shown anything, it is that there is more force available when the apparent wind increases but that applies to all sailing craft.

Moving on to your second post:-

as before the power at the turbine is its torque x its angular velocity. see link about 2/3 down the page http://en.wikipedia.org/wiki/Torque

I am in broad agreement on this. The propeller will be moving so slowly as to have no practical effect on the water. If it was a set of cogs providing the reduction, there would eventually be movement when all the slack was taken up.

Your third post

The formula P=FV works for the propeller in terms of thrust x the speed of water through the propeller rather than boat speed.

The energy comes from the wind. It is the same as any wind turbine such as those used for electricity generation. By transferring the energy from the turbine efficiently to the water, via the propeller, the modest amount of drag and friction is easily exceeded and the boat moves into the wind.

 

You can not only go directly upwind. You can even go directly upwind faster than the wind. The simplified mechanics for a wheeled vehicle shown here, starting at 1:30:



A boat would use a water-propeller instead of wheels.

 

OK The model's in the Herreshoff museum. Was there a date on it?

 

I'm working from memory here, so you should check with the Museum to make sure. I recall Halsey saying that his father, Sidney, made it as a young man, which would put it in the early 1900s.

Cheers,

Earl

 

Thanks, I thought Capt Nat made it.

 

I was amused by the original article that likened these wind powered yachts as being "satellites on the ocean,"

I have been in satellite communications and I never knew that satellites drifted against the wind. The moon is a satellite and I am concerned that we have to watch what we build on the moon as the wind resistance may blow the moon backwards.

So now, the moon travels around the earth every 28 days, searching for a breeze.

Enough to get the wind up ya>

 

Well, he was alive then, so it could have been done under parental supervision

Cheers,

Earl

 

sure you can sail directly upwind.

take two conventional sailboats and connect them with a sliding plank and have them tack in and out.

 

Yes, but the sailboats are not sailing direct to windward are they. However, if you sat in the middle of the plank?

 

This video demonstrates how easy it is.

In this video it demonstrates that sailing directly windward is in fact so easy.
It's a mystery to me why such boats have not been developed.
http://www.youtube.com/watch?v=8Rw_qJytbG8

 

We've been over and over this. That gadget was developed by the Herreshoffs as long ago as the 1890s and used as a toy by LFH. Boats don't just go upwind is the reason it's still a toy. In fact upwind is a small part of a good sailboat's bag of tricks. Heavy wind, big seas, breaking waves, very light winds and reaching and running are part of life on a boat too. This thing works over a very narrow range of courses and windspeeds, so it will always be a toy.
If you can improve it, please do and share with us.

 

Correction, Halsey H's father Sidney made it before WW1.

 

We've also been over and over the fact that it was made then etc. etc. (many times). That is not the point. It doesn't mean we can't consider it. Hero in ancient Greece invented a steam engine. That didn't mean they couldn't make them later
"Improve on it" what do you suggest? It already works well, isn't doing something that can't be done elsewhere enough? It doesn't have to be instead of a sailboat, what about as an addition to a sailboat? You might think of a few reasons why it would not work. But they are only theory, you can't point to any instance where it was tried. Actually, it looks like it would work.