Author Topic: 4 Foot prop pics  (Read 1239 times)

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gotwind2

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4 Foot prop pics
« on: November 12, 2006, 08:16:04 PM »
Oh well, I am going to bite the bullet and carve myself a set of Hugh Piggotts blades.

I have his wind turbine plans with the detailed measurements.

I  have searched this board for any pictures of his 4 Ft blade and only come up with this one



They do look a little 'stubby' to me, I assume for good torque?

Has anyone got any more pictures or comments on Hugh's 4 Ft propeller?

I am intending on testing them on my Ametek 30v motor initially - my current P.V.C blades are poor at best.


Thankyou.

« Last Edit: November 12, 2006, 08:16:04 PM by (unknown) »

Jon Miller

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Re: 4 Foot prop pics
« Reply #1 on: November 12, 2006, 01:41:13 PM »
I would say that the smaller the blad the less torque for a givern TSR.  To get the best out of the Ametek you really need to produce a RPM to power out put (in watts) graph.  From this first graph you can find the point at which you get the best compramise i.e. the watts goes up linear with the rpm and peaks, this would be around the point at which the best fit line starts to flattern off.  Find this and read of the RPM.  You also really need to find the average wind speed or at least asume one.  Using the wind speed you need to build a prop that turns at that rpm you found earlyer in you average wind speed thus getting the best power at your average wind speed.  

You can get a programme that determins the cross sections using formulars that i do not know of the top of my head.  Produce a blade from the programmes information, and then you should have a good prop thats apropriate for your Ametek.  I think this is right, please anybody correct me if i am wrong??  

The only other issue i can see is mounting such a set of blades to the Ametek, the bearings on these motors are small and not really up to the job of having a woodern prop as the thrust loads and vibration will make the bearings wear out fast.  I have use similar motors and had to install a secound lot of bearings to handle these forces.

I think thats about it, hope this helps Ben.  

Regards Jonathan

« Last Edit: November 12, 2006, 01:41:13 PM by Jon Miller »


David HK

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Re: 4 Foot prop pics
« Reply #2 on: November 12, 2006, 03:00:44 PM »
Here you are my first attempt at carving blades. They work very well indeed and its a wonderful sight to see them spinning.


It took me one day per blade. Usual tools, tenon saw, mallet, half inch chisel, straight edge. Weighing machine to weigh them before as wood blanks and then weigh them when they are finally carved. Aim to make four blades in case you muck up on the first one - as I did. Once you have done the first blade the rest are easy.Try and buy the timber from one length of plank. Do not buy timber from mixed trees or the weight of the wood blanks will all be different.





David HK

« Last Edit: November 12, 2006, 03:00:44 PM by David HK »

David HK

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Re: 4 Foot prop pics
« Reply #3 on: November 12, 2006, 03:07:02 PM »
Here are some more views and you will note that I am using an Ametek 40 volt motor on Hugh Piggots design. I modified his mounting a little bit to accommodate the motor. It works very well.







David HK

« Last Edit: November 12, 2006, 03:07:02 PM by David HK »

gotwind2

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Re: 4 Foot prop pics
« Reply #4 on: November 12, 2006, 03:11:49 PM »
Great stuff - just what I needed to visualize my new prop.


Thank you guys.

« Last Edit: November 12, 2006, 03:11:49 PM by gotwind2 »

Speo

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Re: 4 Foot prop pics
« Reply #5 on: November 15, 2006, 11:40:47 AM »
Hi,


Mine is here: www.windpulse.com


Speo

« Last Edit: November 15, 2006, 11:40:47 AM by Speo »