"On the can props, a comment was made that their pitch wasn't really
helical, I thought that with the correct size can and tilt angle it was
helical in pitch, not so ?"
Not so. The rate of change in blade angle on a can prop is constant. A
plot of blade angle versus radius is a straight line. For each inch you move up
the can, the point of tangency moves a fixed angle around the can. The rate
of change of blade angle on a helical prop follows a tangent curve.
There is a way to lay out the prop around a curve, rather than a line, that
will produce a helical prop, attributed to Jean-Marie Piednoir. I will post
my assembled notes on this subject in a subsequent email.
Cone formed props have a linearly varying rate of change of blade angle and
can give a slightly better approximation to a helical pitch. A curved layout
line on a cone can give perfect helical pitch.
Gary Hinze
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Received on Sat Dec 02 2006 - 02:24:27 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:44 CET