10' rotor

[97fishmt]

Here is a set of blades I just got done and ready
to try out on a new servo motor.

I built it using the blade calculator on that other
wind site.  I hope I come close to having it cut
in at 7 or 8 mph to take advantage of the light
winds at my site.

[SparWeb]

It looks like a fair enough twist.  The tips look like they're at about 0 degrees, so are you aiming for high TSR?
There are blade calculators all over the place, so you'd have to be more specific.  I'm guessing they are the Piggott design?

[taylorp035]

I would be careful with going with such a low angle tip.  My 66" blades that I made for my treadmill had tips that were very close to zero, which made for awful start up performance and very inefficient at 15+ mph.

I guess now you have to put them on and see if they work  

[97fishmt]

Hi SparWeb,
It was the warlock calculator. Yes the tips are
0 degrees. It's all a compromise though with
the wood thickness you use.  The calculator
only gave me an idea of what sort of rpm I could
get out of a 10 rotor. I want to be able to capture
some of the breeze.  I just had some cedar laying
around and well that's what came out. We'll see
how it works.

[97fishmt]

Hi taylorp035,
I've made many sets of blades and never
had a problem with start up. The servo
motors I play with are brushless. I'm
just using up some cedar that's been laying
around for about 5 years.

The new tower makes it easy to swap
motors and props. The motors cut in range
from 97 to 185 for 12 volt charging.

Just playing around

[SparWeb]

Since I have motor conversions, I keep in mind there is a starting torque due to magnet attraction.  I think you've already said it's very low in your servo-motors so maybe less of an issue that it is for me.
I haven't experimented with Warlock's calculator in a very long time.
You could try Hugh Piggott's spreadsheet for your next one - or reverse-engineer this one with his method.  I've found it to work quite well for me.

97 RPM @ 8 mph using a 10' blade is  TSR = 4 so the blade would be pretty close to stall if you did that.  On the other hand the 185 RPM connection would cut-in with a TSR closer to 8 and maybe it's already spinning in wind speeds less than 7 mph, making something for you right away.  Having a high TSR at cut-in is a double-edged sword.  The power thru a 10' prop converted into 12 volts is a heckuva lot of amps.

[97fishmt]

SparWeb,
The cut in speed for the motor I wanted to try is around
167 rpm for 13.2 volts, but wanted it to also maybe work
on the larger motor 183 rpm.  I have seen over 80 amps
out of it.  The name plate list 65 amps I try to stay below
that now that I got the furling working properly.

The 97 rpm motors will probably work nicely at 24 volt.
Around 188 rpm for 25.2 volt.  So the large cord at the
root, 11 inches and the faster tip 3 1/2 inches, with no
angle for drag,more lift, might be OK. I hope so it came
out beautifully.