hey guys ! a new type of windmill (french site)

[Evil Roy Slade]

@mine

Interested in your new design and would like to see a diagram.

I assume at this point you don't have any performance data although you mentioned
doing simulations that may give me some guide.

How are you controlling the foil position to get the right attack angle?

ERS

[minesapint]

Foils are controller by worm geared dc motors. At the end of each boom.
Each shaft is encoded.
Wind direction is known using a weather vane or I did toy with the idea of using ultrasonics.
PWM drivers speed up or slow down the blades at certain points.
Blades switch tact at points A and B.
The whole thing rotates slowly, low noise (no tip speed noise as such), can be geared or use multipole genny.
Is also probably a lot less noisy (clutter wise) to radar, less curvey bits for multiple reflections.

[Evil Roy Slade]

@mine,

Thanks for the diagram. You said in an earlier post that your aim is to position the foil
at 20deg angle to create lift perpendicular to wind direction.

I believe the aim should be to create lift tangential to the circular path in order to impart
maximum torque.

The principle is the same but our switch points would be different.

Have I interpreted your diagram correctly?

ERS

EDIT: How did you do your simulations? Did you write some code or use something already available?

[minesapint]

lift tangental to circular path......
Possibly although to do this you need to increase the angle of attack to greater than the stalll angle.
All of this is controllable in software - once I have a working prototype I would tweak it for maximum output. The sims I ran assumed pependicular thrust. I was not able to take into account the wake of the preceeding blade - the maths got too complex - its all navir stokes type fluid dynamics stuff....
The main problems are accelerating the blades at point A nad B such that it changes tact. You need a very light blade and powerful motor.
I have asked companies to make parts of the turbine for me and getting a blade strong enough and light enough seems to be the sticking point - no one could really do it within budget.
I guess now as I have come clean with the design its 'open source', I would love to get this thing made as I said I have done the control parts, just need the mechanics.

[Evil Roy Slade]

Yes I see what you mean about the stall problem.
The tweaking would involve getting the best foil position to maximise the lift vector in the
tangent direction without going into stall state.

It's great that you have shared your idea.

I know you are developing a prototype. I would also like to have a go
at a small scale static prototype. By static I mean to fix the wind direction using a fan.
Its not ideal but ok to do some experimenting. I would then use one symetric foil in fixed position
attached to a sensitive strain gauge to measure its lift in the direction I want it.

From here one could then develop the foil settings matrix to be used by the controlling software.
I know you have probably already done it but this step will give me some evidence that the system
will work as expected.

If at this point I consider it a reasonable chance at success then a full scale proto will be built. Hopefully at this point you could jump in with your expertise.

Finally, although you said your idea is effectively now open source I still consider it yours. Hence I would like your permission to build the small scale prototype.

ERS

ERS