Increase Lift of blades by modifying leading edge

[Matrix1000]

I just ran across some interesting information regarding blade technology that can easily be used for home systems.

By channeling air at the leading edge of a blade, lift at low wind levels is greatly improved. Looks easy enough to implement.

Prototype tests to date have demonstrated "outstanding performance," most importantly during light winds, with the tubercle-lined blades capable of more than doubling performance at wind speeds of 8 metres per second. "We're getting the kind of power (regular blades) produce at 8 metres per second at 5 metres per second."

"research colleagues at Duke University and the U.S. Naval Academy saw 32 per cent lower drag and an 8 per cent improvement in lift"

They also discovered that the angle of attack of (a modified blade) could be 40 per cent steeper than a smooth (blade) before reaching stall - that is, before seeing a dramatic loss in lift and increase in drag. In an airplane scenario, that's typically when you lose control and crash."

"That stall typically occurs on most wings at 11 or 12 degrees at the angle of attack," says Fish, adding that with the humpback design "stall occurred much later, at about 17 or 18 degrees of attack. So the stall is being delayed."

http://peswiki.com/index.php/Directory:WhalePower_Corp#Official_Website

[chadking]

Thanks for the info!  There are a couple people on this board that have been doing experiments and keeping their eye on developments with tubercles.  I believe some of the original research on tubercles came from studying the fins of whales.

[spinningmagnets]

There may be some useful information that is applicable to this line of experiments in the data concerning aircraft slats. A slat is a long slender surface that matches the shape of the front edge of an aircraft wing. During take-off and landing the lift of the wing can be increased by extending the slat forward a small amount. During flight it is often retracted to reduce top speed drag. (springs hold VAWT slats out, a speed-ball steam governor spinning retracts them?)

Many planes used slats, and the WWII German Fieseler Stork (Fi-156) was famous for its short take-offs and landings due to its advanced slat design.

http://www.liming.org/ch801/slathistory.html

http://en.wikipedia.org/wiki/Fieseler_Fi_156

"I'm allergic to cocaine, it makes me break out in handcuffs" -Robert Downey Jr.

[elvin1949]

 Rotornuts [Mike] was working on this a couple

of years ago.

later

Elvin

[bob golding]

hi, very intersting idea. here is the link to mikes experiments.

http://www.fieldlines.com/story/2005/6/21/195648/852

cheers

bob golding

[hiker]

hmm - somthing like the old ww1 aircraft with there cloth covered wings--the spars in the wings created channles somewhat..

[iamdewayne]

Your theory is correct.

The WW1 aircraft did use channeling ( although they didn't mean to ) it was the only way they knew to keep weight down. In the 40's and 50's, we used the principal on our airplanes, and so did everyone else ( they are nick-named 'fences' ) just look at a mig 15 or any of our early jets or fighters from WW2.

The spars are actually buried down below the covering and run the length of the wing, what you are seeing in the picture is the ribs of the wing which give it it's shape along with the cotton fabric covering which is stretched over the surface.

Slats are an entirely different animal that direct airflow ( which would have otherwise detached due to a high angle of attack ) from the bottom of the wing through a channel and across the top of the wing allowing lift to be generated well into the stall.

One thing to remember when trying to create your own blades, you can't use wing sections without changing them as they wont work. Wing cross sections are great at the size they are designed for, but when you scale them smaller, they lose their efficiency.

Very cool article! ( Ya ever notice that they keep 'inventing' stuff thats been around for almost a hundred years?.....)

Dewayne