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1. 03:45 AM - Re: KIS TR-1 Propeller (BlueSkyFlier)
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| Subject: | Re: KIS TR-1 Propeller |
Chuckle chuckle ... [Laughing]
Hi Galin. I was thinking of you when I did the write-up because I did previously
say to you that a 3-blade prop is rarely if ever better than the 2-blade --
that statement still holds if both prop types have the same pitch.
In such case the one advantage of the 3-blade is that the lower power loading per
blade reduces the lift coefficent on the blades. Therefore the 3-blade stops
cavitating (starts to 'bite' properly) at lower forward speed than a 2-blade
generating the same thrust. Takeoff acceleration therefore benefits. The price
to pay for that benefit is the higher parasitic drag of the 3-blade prop.
In any case, reducing the propeller pitch is what really makes the difference and
is essential to release the extra RPM needed to tap into the top end of the
'full throttle' curves at any % remaining power. The parasitic drag penalty is
offset by reducing the diameter accordingly.
One important observation from these studies is that steeply banked turns should
be given a wide berth in the KIS TR-1 if you have less than 130 hp up front
coupled with a propeller pitch in the high 60"s. Anything more than 55 degree
bank has the potential to really spoil you day - and everyone else's too.
[Bonbons for those who spot the obvious little booboo in two of the labels on the
diagram :o)]
Cheers,
Alfred
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