europa-list
[Top] [All Lists]

P-factor

Subject: P-factor
From: Nic <tgynz@cts.com>
Date: Mon, 19 Mar 2001 14:37:05
TWIMC,

Propeller factor or 'pitch' factor is the effect of the advancing blade
(helicopter lingo) which is at a greater alpha than the retreating blade.
A clockwise propeller rotation when tilted during takeoff and climb (normal
for most planes) will result in more thrust from the starboard side of the
propeller disk.
Hence the need for prolonged rudder input during these phases of flight.

Also there is the slipstream that spirals around the fuse and smacks the fin
on the port side.
Bigger planes have the fin offset a few degrees to compensate.

Also bigger planes' thrustlines are tilted down to moderate trim and rigging
extremes.
You don't want: Gun it when aborting landing and climb into a stall.
You still want: Chop the throttle and have the nose pitch down.

My father, a Marine test pilot in Coarse-Aires and AD-1's, just called it
torque.
Big birds w/ radials and 11 ft propellers like that definitely have
precession effects at minimum airspeeds.
That's also how stunt planes with heavy metal propellers and alotta power
can screw themselves into such wild spins.

But not our little birds.

IMHO
3
Striving for less than pompous,
Nic - A&P '83 - xs145
:)

A joy to learn / a joy to teach.

Inaccurate definition site....
http://www.gluckman.com/harry/aviation.htm



<Prev in Thread] Current Thread [Next in Thread>