On 04/16/2010 01:26 PM, rampil wrote:
> ....most commercial GA aircraft have two blade props...
> Actually as can be seen convincingly in a stroll about Sun and Fun
> today, any new, high performance aircraft , i.e., Cirrus, Cessna,
> Mooney, Lancair, etc., etc., has 3 blades.
It has a lot to do with sound. A 3-blader produces less sound.
Furthermore it has less vibrations, and to some folks looks sexier.
Performance is another subject.
A 2-blade prop IS more efficient. The tips of the prop slice through the
air with almost the speed of sound, if you have two tips instead of
three, you reduce drag quite a lot.
If is the same question versus a two wing airplane or a bi-plane. A
bi-plane has more drag because it has more frontal wing surface. More
wings is not more efficient, just like more propeller blades is not more
efficient.
My propeller still converts the same amount of engine power to thrust,
but it has less frontal surface slicing through the air. Once I' flying,
I will be happy to share performance data.
And no, no first flight today. :-( The whole airspace has been shut-down
because of the volcanic ash.
> Just because most aircraft designed 30 years ago or earlier had
> two blades doesn't mean that it was best for aerodynamics, just
> best for the marketplace at the time.
Well, then this must have been the reason the bi- and three-plane
airplanes vanished from the market as well? Just because two wings was
cheaper?
Frans
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