Wind Turbine Brake Idea

[Flux]

I think you may have misunderstood my point.

I agree with you that a brake or other back up that doesn't rely on the alternator is a good idea. For most machines the alternator is perfectly capable of doing the job but you have no back up if anything else fails.

I can't see the point of devising a complicated eddy current brake that will only slow it but not stop it and have this back up relying on coils and circuitry and wiring that could fail at the same time as alternator connections. If this was a simple and cheap brake then I would agree but for something more complex and costly than the alternator it seems not to be going in the right direction.

Probably to keep speed under control but not actually stop the thing, tip flaps as used on many larger machines may be the way to go. With your projecting rear shaft you are ideally placed to make a mechanical brake that would be much less costly than the eddy brake and you could use it to hold it stopped.

You make a valid point about large commercial machines but in that case so much depends on these back ups that it doesn't really matter if they do cost a fortune and they also have a full maintenance and test programme to make sure the things stay in working order, small machines rarely get any maintenance until something is obviously wrong or has failed and also a one off brake design will not be tested and proven in the same way as the brake on a commercial machine.

I hope you get it to work but I suspect you under estimate the complexity of something needed to absorb the full force of a runaway 10ft machine in a storm and dissipate it as heat.

Flux

[Dave B]

  No need to re-invent the wheel. Auto furling, shorting switch and manually cranking the tail. This combination has been used successfully for many, many years to control the turbine and the mechanics are already in place.

  Funny how stator burnouts seem to go away then also.

  Dave B.

[ChrisOlson]

The horse and buggy, wooden wheels and dirt roads worked fine to move people and goods from place to place for many years too.  I believe when the automobile first appeared many people shunned it as a useless and unreliable machine.

What a difference a few years of progress makes.

I got my 7.6 footer flying again with the eddy brake on it.  About an hour ago it was putting out 414 watts with the wind blowing at 15-20 mph.  I pulled the fuses on the rectifier to unload it and let it free-spin.  Then flipped the switch on the eddy brake to see what happens.  It stalled the airfoils in less than 2 seconds.

The brake DOES work.  The faster the aluminum brake rotor turns, the more effective the brake is.  Now all I have to do is wait for another day when we get 25-30 mph wind and see how it works at higher loading and speed.

I know many people don't think a turbine brake is necessary.  But I love experimenting with things.  If it wasn't for people like me we'd still be moving things with the wagon train - and using stators and tail cranks to stop wind turbines.

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Chris

[ChrisOlson]

I neglected to check rotor rpm before I tested my eddy brake for the first time in a real world test.  But since the turbine was making over 400 watts of power, and I disconnected that load, I have to assume that the eddy brake is capable of converting at least 400 watts of mechanical energy to heat.  Or, if I was calculating the effectiveness of an engine retarder on a diesel engine, it generates at least .54 brake horsepower.

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Chris

[carbethhutter]

Hi About furling,why all the maths to work out tail fin furling angles.cant u just hinge the tail fin and use a sat jack arm, to adjust the angle while in flight in relation to /charge /wind speed/noise/ect.run the two wire down the pole for the desired efect.Anybody tried this yet.