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1. Why are there only three blades on most windmills?
2. Why is the tail on passenger aircraft so large? Why have they not gone to a wingtip drag mechanism? Does it really take the huge vertical wing to keep the plane straight?
3. damn, forgot the third one.
P
My speaker building site
Follow Ups:
Q. why is the glass twice as big as in needs to be?
roN
1. I've wondered the same thing. I suspect it's a tradeoff so that the windmill has reasonable efficiency and minimal vibration at a large range of speeds. Presumably at low speeds if you had a bunch of blades the air that one blade "dirties" (disturbs) would be run into by the next blade. At only three blades a pretty small airspeed is sufficient to allow the "dirty" air to move past the plane of the blades before the next blade bites into the same space. Dirty air would cause vibration and stress on the blade and the hub. That's all a guess.
2. The tail is mostly responsible for which way the plane's nose points. The ailerons are mostly responsible for turning, though the rudder helps. The elevators point the nose up or down, and help control lift and descent (along with throttle setting and flaps). The size of the rudder is a tradeoff between control at low speeds (big rudder) and minimizing drag (small rudder). There are a few planes such as the B-2 that have no vertical stabilizer, and use computer-controlled differential drag for control.
3. Thursday, orange, or butterscotch.
3 blades are more dynamically balanced during wind load variations than 2 or 4 bladed units. They operate smoother as those stresses are focused at the turbine. Also 3 blades is more aesthetically pleasing to the eye. A big deal when placing a few thousand of these things all over the Tehachapi Mountains.
Despite not being an Engineer....
1. Two is too few and four is too many.
2. That's how the plane is steered in flight, with the rudder on the tail. The ailerons are used only for takeoff and landing.
3. 42
Nice!
("....and thanks for all the fish!")
Jim
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not an engineer... but three vanes probably easier to balance? as in a tripod
1) dunno
2) dunno
3) you're getting old
:)
Dr. Who, A Christmas Carol, "Like I say, Lucky"
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