Re: Inspiration for Homebuilders

Orval Fairbairn wrote:
In article <DqkTl.3233$he4.1275@xxxxxxxxxxxxxxxxxxxxxx>,
Charlie <mcsophie@xxxxxxxxx> wrote:

Orval Fairbairn wrote:
In article <b83Tl.1594$cW.1334@xxxxxxxxxxxxxxxxxxxxxxxxxx>,
Jerry Wass <wassbiplane@xxxxxxx> wrote:

Orval Fairbairn wrote:
In article <cm0Tl.27375$c45.9636@xxxxxxxxxxxxxxxxxxxx>,
Brian Whatcott <betwys1@xxxxxxxxxxxxx> wrote:

Orval Fairbairn wrote:
In article <1lGSl.30936$YU2.8034@xxxxxxxxxxxxxxxxxxxx>,
Brian Whatcott <betwys1@xxxxxxxxxxxxx> wrote:

This is a pointer to a home build 20 ft diam windmill on a 70 ft pole.
It features three 10 ft long laminated red cedar blades and nice looking generator, tower couplings and gin....


http://www.otherpower.com/20page1.html

Brian W

(Thanks to Larry for the pointer on rec.boats)
I hope that you have good lightning suppression!

Ha! I noticed the maker specified a blade angle of 3 degrees at the tips, increasing to (approaching) 9 degrees at the roots.
It took me a little while to get my head round this. The maker mentioned the blades are set flat (undersurface) forward into the wind, and I think he mentioned a target rotation rate of 65 rpm.
I imagine he was thinking of an AoA of 15 degrees at the rated wind. The tips do a revolution in pi x 20 ft = 63 ft per rev - so the rotation rate at 65 rpm would give a tip speed of 65rpm X 63ft/rev X 60 min/hr / 5280 ft/mile or 47 mph.

I guess the pitch angle for zero AoA at the starting windspeed 16 mph would be atan 16/47 = 19 degrees from the plane of revolution, so for 15 deg AoA the pitch angle might be 4 degrees from the plane of revolution at the tips.
And he mentions 3 degrees. But getting up to speed with stalled blades would be an issue...
What's your take, Orville?


Regards

Brian W
My first take is that you misspelled my name.

We had a big windmill on our farm when I was growing up. The plane of rotation was parallel to the wind, rather than at a right angle. The fan acted more as a wind turbine than a propeller. IIRC, the fan had about a dozen curved steel blades. It also had a brake on it for when the winds got too high.

The blades were turned sideways (parallel to the tail) if they didn't want it to pump any water---If you needed water you operated the lever that placed the blades perpendicular to the rudder, tail, whatever,-pointing into the wind, then you got some POWER..---OR--
did you have one of those weird looking things where the blades were raked back severely at an angle about like the back 2/3 of a snowcone cup? Jerry
Neither. The fan was 10-12 ft diameter, fixed so the wind would always turn the fan. Since the blades were curved (cambered), the advancing blade had less drag than the receding blade. I think it was a Fairbanks-Morse product, but don't hold me to that, and it was built about 1910.

A lot of windmills in our area (Northern Illinois) were of similar design.

Sounds like a pelton wheel.
http://www.google.com/search?hl=en&q=pelton+wheel&aq=0&oq=pelton+w&aqi=g10

Nope -- it wasn't a Pelton Wheel!

As I posted earlier, I thought it was a Fairbanks-Morse model.

See the picture at: http://www.agwt.org/store/FairbanksWindmill.htm

The fan disc was parallel to the wind direction. This raises the question: Could we dispense with the directional pivot and mount the fan horizontal to the ground? It should be able to rotate with any direction of wind.

Of course, good lightning protection is a MUST!


If memory serves the vane's angle could be manually changed as needed for variations wind speed.

Dan, U.S. Air Force, retired
.

Relevant Pages

  • Re: Inspiration for Homebuilders
    ... Brian Whatcott wrote: ... The maker mentioned the blades are set flat forward into the wind, and I think he mentioned a target rotation rate of 65 rpm. ... I think it was a Fairbanks-Morse product, but don't hold me to that, and it was built about 1910. ...
    (rec.aviation.homebuilt)
  • Re: Inspiration for Homebuilders
    ... Brian Whatcott wrote: ... The maker mentioned the blades are set flat forward into the wind, and I think he mentioned a target rotation rate of 65 rpm. ... The fan acted more as a wind turbine than a propeller. ...
    (rec.aviation.homebuilt)
  • Re: Inspiration for Homebuilders
    ... Brian Whatcott wrote: ... It features three 10 ft long laminated red cedar blades and nice ... I imagine he was thinking of an AoA of 15 degrees at the rated wind. ... the fan had about a ...
    (rec.aviation.homebuilt)
  • Re: Inspiration for Homebuilders
    ... Brian Whatcott wrote: ... It features three 10 ft long laminated red cedar blades and nice looking ... I imagine he was thinking of an AoA of 15 degrees at the rated wind. ... I guess the pitch angle for zero AoA at the starting windspeed 16 mph ...
    (rec.aviation.homebuilt)
  • Re: Inspiration for Homebuilders
    ... Brian Whatcott wrote: ... I noticed the maker specified a blade angle of 3 degrees at the tips, increasing to 9 degrees at the roots. ... The maker mentioned the blades are set flat forward into the wind, and I think he mentioned a target rotation rate of 65 rpm. ...
    (rec.aviation.homebuilt)