Propellers

On Thursday, May 6, 1999 at 12:00:00 AM UTC-7, Steven Estergreen wrote:
Point taken, although I apparently didn't write precisely enough, either. What I
meant was that the "rolling moment" didn't produce a rolling motion of the aircraft.
Thinking it over, I guess the more usual term for a moment that produces a rolling
movement of the aircraft is "roll moment," as compared to a "yaw moment" or "pitch
moment." And "rolling moment" could be interpreted more generally, as a moment that
is produced by a force that is constant in direction, but rotating at some radius
from the coordinate system of interest. It wouldn't necessarily, but could, relate to
aircraft. That appears to be what you meant.

highflyer wrote:

Steven Estergreen wrote:

Actually, rather than a rolling moment, the one bladed prop would cause
alternating pitch and yaw. The asymmetric force rotates around the longitudinal
axis of the aircraft, but is aligned with it. So any moment produced acts about
the pitch or yaw axis, and would not produce the motion commonly referred to as
"rolling", rotation about the longitudinal axis.
Yeah, I know, semantics....



Semantics indeed Steve. That IS a "rolling moment about the hub"
which is, of course, rotating. Therefore the rolling moment about
the hub is felt by the airframe as a moment in constantly changing
directions, but always away from the single blade. It doesn't do
any good to write precisely when you don't read with equal precision!
g

HF

EVEREL! check out everel props used on early piper cubs one blade high performance, smooth at all speeds. don't let the engineers discourage you. i find engineers are confused by their own brilliance.