Ben's PVC blade improvements

[gotwind2]

I have been experimenting with P.V.C blades for over 12 months now - I know they are not great but adequate for the tinkerer - I live inland on a very low wind site, it is mounted in my back garden...

I needed plenty of torque for low speed start up so I made a 'fatter' root section to most plastic blades.

They spin beautifully when properly balanced, and took 1 day to complete the blades and balancing - 4Ft diameter prop driving Toms Ametek 30v DC motor.

I will be painting the blades white soon - just wanted to test it today. Happy.

Video below - wind gen is connected to a 10W load in a mere 4 mph wind.

http://www.youtube.com/watch?v=sxxDOHlR6uE

[fungus]

Pretty nice looking. It looks like a similar profile to hugh piggotts wooden blades. Have you seen much performance boost after installing the new blades?

[tecker]

Looks like you need to set a slant to put the cord  into the wind there. They're turning backwards you'll get a more power with the cord lift . That added area might have to drop closer to the hub with the right canter to the blades.

[Flux]

They look odd built that way but it does simplify the mounting and generally it seems a good idea. Reminds me of TLG blades.

From the pictures it looks as though the angle reverses at the tip but I am sure it must be an illusion.

Flux

[gotwind2]

Yes Flux. The hub was a TLG bought one, I think he laser cut's them, I had his 'Tri-Nado MM' aluminum 3 Ft diameter blades on it.

They worked well in a good wind, however in my location i needed more start up torque.

These new blades are doing the job, I need good wind to test to full potential.

The angle at tip of the blades is an illusion of my camera.

Cheers

Ben

[Dave B]

Great idea for design and mounting the blades that way. Let us know how they perform, PVC blades are not typical to begin with, this could be a better way. Dave B.

[tecker]

The cord is postioned for clockwise rotation .In the clip they turn counter clockwise   You have the cord perpedicular to the roational plane you aren't getting any lift that way . The rotation is just draging from the curve you just added. Just  roll the blades

15 to 20 degrees and drill new holes .Check the Jerry's Airheads page the drag is best behind the lift section of the blades .

[nothing to lose]

Nice blades Ben,

I can't tell in the pictures but it looks to me the tips are still square and I looked at the ones on your site before also and I think they  were squared.

Have you tried rounding the tips, kinda like a half circle, and also sand them down thinner like a taper from about 1-2" to tip. That's how I was doing mine and I liked it alot better than a square tip myself. I think they were faster and less noise that way.

I also rounded the leading edge and feathered out the trailing edge thinner for better smoother airflow around the blades.

I haven't made any blades for awhile, been busy, but I'll be making them again in about a week when I get the little shop set back up here. Also will be playing with a new blade idea.

 E-mail me a shipping address if you want and if shipping is not too costly I may send you a couple things later I will be playing with here.

[gotwind2]

Thanks nothing to lose for your comments, the above blades are only slightly radiused.

I will be bringing the tower down soon, and will experiment a bit more with 'feathering' and  a full radius.

Thanks for your offer, can you keep your progress recorded in the diary section, I visit here daily - I will be interested to see your next set of blades, and may take you up on your blade offer - Paypal postage payment can be met, no problem.

Cheers

Ben (UK)

[Jerry]

Hi NTL.

I must agree with you. Rounding the tip does make them quiet and yet speed them up at the same time. The square tips seem to flutter and stall.

Your blades do look just like mine. Or should I say my blades look just like yours? LOL.

Here a couple pictures of some 4 ft blades. The first 2 are of the 1/16" thick wall pipe.

The other pictures are of the foam centered 5/16" thick wall pipe. This stuff is very stiff do to the skin-foam-skin lamination. I made this set from 6" ID pipe.

Soon I'll have some 8" diameter foam pipe. I'll try making some 6ft. blades with that.

Now the thick pipe.

Hope thats not to many pix?

                           JK TAS Jerry

[Slingshot]

It looks as if you have a nut on the end of your motor shaft.  Was it threaded?  How exactly are is your hub-to-shaft setup implemented?

[nothing to lose]

Our blades do look the same almost.

I been busy moving stuff into another trailer and not online or doing much for last couple weeks. If weather clears up I'll be doing allot more outdoors, got that cold spell here unexpected this time of year and that slowed me down on everything again.

I should have some blades made up in a few days again and be tryng out the 6 pole motor you said to try as 4 pole with each coil seperate. I did that motor as 1/2" disks 4 per pole as 4 pole last night, much better but still coggs allot. I'll post that elsewhere later.

I will be trying a new 6 blade hub I had made and PVC blades on that motor.

Nice thing about this NTLsuper6 hub design is I can fly 2, 3, or 6 blades on it. So first I'll try 3 blades as normal and see if I get past cogging, if not I'll add another 3 blades. 1/8" steel plate so the hub should handle most anything.

I am thinking with the PVC blades we make perhaps when we have a good motor for power but bad cogging maybe try 3 longer blades for the speed and power once spinning, 3 shorter blades for starting torque to break past cogging. It's a compromise between a 3 blade and 6 blade rotor. Basically I geuss a 3 blade for TRS but with 6 root areas nearer the hub as I will try it a few times just to see. That 6 pole motor may work well if I can break it past cogging. In drill press lowest speed 760RPM I was getting 5.4Vdc from just one coil, brought up a string of dead Ni-cads to 5.4V fast, but I didn't get much tested otherwise yet.

The Hub is usable for any normal 2 3 6 blade rotor setups.

I also had other hubs cut for seperate rotors of 3 5 7 blades, So I think when I get the 1 blade and 4 blade hubs I have everything covered up to 7 blades now

I wish I had some PVC blades made up now and ready to fly on that motor as a 3 blade, strong winds here today all day!

[nothing to lose]

I should have some things done soon, I got tied up with other stuff for awhile.

Should be getting a laptop soon and that will make posting allot easier since the trailer I moved into and working in now is mostly offgrid, 1 LONG extension cord for grid power for small drill press etc.. but otherwise no power but batteries and inverter. So my big PC is not down there yet, but the laptop will be and I can do up posts as I am doing stuff then upload from here later.

Also the other trailer where I am mostly at now has no internet available.