rje@cae780.UUCP (Bob Evans) (09/20/85)
I know I'm coming in on the end of this discussion, but since I happen
to have the manuals for the airplanes, I thought I'd slip :-) in my
two cents worth. I have manuals for
1980 C172-RG
1982 C172-P
1892 C182-R
1983 C152
In only one of the manuals are slips and flaps mentioned together -
The 1982 C172-P. The manual says "Steep slips should be avoided with
flap settings of greater than 20 degrees due to a slight tendency for
the elevator to oscillate under certain combinations of airspeed, sideslip
angle, and center of gravity loadings". The manual also calls for a placard
located near the flap extension lever "avoid slips with flaps extended".
All of my time (150 hours) has been in Cessnas -152, 172, 172rg. Only in
the ships with 40 degrees of flaps (all 40 degrees used) have I ever
noticed the oscillations mentioned - it appears to have about a 1 to 2 foot
amplitude. The conditions were - full fuel, forward CG, steep descent
with full (controls full over) slip, airspeed 60 knots. The oscillations
have a period of about 1-2 seconds. There never _seemed_ to be any
danger of loss of control. BTW my instructor (ex-navy fixed wing, helo, CFII)
said that the oscillation was caused by momentary blocking of the airflow
over the elevator, but that it was obviously :-) self-correcting ...
At any rate, I've never experienced any problems due to slipping with
the flaps out.
Bob
FROM: Robert J. Evans, CAE Systems Division of Tektronix, Inc.
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