Backcountry Pilot

[courierguy offline]

Quite a lot it turns out. They have the ability to tilt their airfoils (fins), to very steep angles of attack without stalling. A series of ridges, called tubercles, along the leading edge of their fins allow this . This "technology" is being used by a wind turbine blade manufacturer for up to 20% more power. Wind tunnel tests show in some cases up to 40% push back of the stall angle. Use of the technology is also being used by industrial fan maufacturers. Noise is reduced by 1/5, and span wise flow ELIMINATED, and less power is consumed. Any aircraft propellor manufacturers on this ? It sound for real, they are in production. More thrust using less power, and less noise, I want one NOW!
www. enviranorth.com
www. whalepower.com

I read about this in my latest issue of "Windpower engineering", nothing was mentioned as to whether or not the whales tried vortex generators first.

[wirsig offline]

That had been discussed some over on supercub.org. whale thread
There's even some pics.

[courierguy offline]

Well, I didn't say it would LOOK good!

[mountainmatt offline]

Maybe it would look better on a prop. Interesting technology though (wing boobs?).

[Terry offline]

I have heard of wing tips but never wing tits.

[Stol offline]

I was about to buy into this concept till I saw the " nipples" on those wing boobs.

[mountainmatt offline]

Is it cold there?

[Jaerl offline]

That is what happens when you try to combine your two favorite hobbies.

[PA12_Pilot offline]

According to one of the papers cited on whalepower.com, the tubercles work at a Reynolds number (Re) of 1.8x10^5. We need Jerry Burr to tell us the Reynolds number at which our airfoil works. If they are similar, then the tubercles might work for us.

Update (12/22/09):
I was unable to find the design Re of our airfoil, but I did find a paper which indicates that tubercles won't work for us.
From the paper:
1) "Reynolds number <1x10^6 are considered low Re numbers"
2) "Clark Y airfoil was not designed for low Re"

3) Although the Clark Y is not used on the Cub, it is used on a number GA planes, including many Aeroncas, the Aviat A1A (a Clark Y / USA 35B blend), CallAir, the Fleet biplanes, the Monocoupes, and many others. Piper J4s - through PA-20s use the USA 35B, and presumably they operate at Re similar to the Clark Y.
4) Tubercles work at Re = 1.8x10^5
Therefore tubercles won't benefit our planes

You can find the paper here: http://www.caselab.okstate.edu/ocharle/ ... rfoils.pdf (it is an interesting read and well illustrated) and you can find a list of airfoils here: http://www.ae.illinois.edu/m-selig/ads/aircraft.html.

Eric

[EZFlap offline]

If there's any trained aerodynamicists lurking in these waters, I think they would agree that those angled ridges ARE indeed vortex generators (assuming the whale tubercules look like the photo of that airplane wing). At high AOA they would shed vortices back along the wing (fins), because of the same physics. Chordwise energized vortices act as flow fences (eliminate spanwise flow) and they energize the boundary layer (delaying separation).

The angled strakes on modern high speed aircraft, and the leading edges of delta wing aircraft, are big vortex generators. The whale tubercules (again assuming they look like that strange airplane wing in the photo) are very similar in function to these strakes or "chines". Reducing drag during maneuvering is probably a big deal for the whale... things make a LOT more drag and take a LOT more muscle force to overcome in water than in air.

Next thing you know, we'll find out that mother nature also invented slotted Fowler flaps a million years earlier... look at the wingtips on an Eagle or Hawk when they're in slow high lift flight

[courierguy offline]

The industrial fan showed on Enviranorths site seems to be pretty attainable with current prop manufacturing capability, at least the composite type construction. Obviously I suppose, or they would not be producing them. So... Warp Drive, Kiev,Ivo, Sensinich... get on it, I want one now! I'll hold off on the wing LE modification for a while, as the practical application of the design there could be a bit awkward, not so the prop apparently.

[tempdoug offline]

Also notice the bumps on the side of the fuselage.