>> Perry just as a matter of interest please try a forward slip at
high
>>> altitude and
>>> tell us what happens. For example is the canard stable or
>>> does it buck in yaw or pitch? I am curious. The C 172 with full
>>> flaps pitch bucks a little bit in a forward slip.
>>>
>>> Paul Lamar
>>
>>
>> All Cessna's that I've flown do this.. I think you'll find that
most
>> [if
>> not all] Cessna singles [ other than the 208 which I've not flown]
>> are not
>> approved for slip's w/ full flaps. I used to get into a
divergently
>> unstable pitch situation all the time w/ a 182 when flying
>> skydivers.. it
>> was controllable when you were expecting it.. when you weren't [
the
>> first
>> few times it happened] it got your heart pumping.. Mind you..
these
>> where
>> Max rudder on a straight tail 182, w/ enough bank to keep the
heading
>> straight and then forward pitch until you reached Vfe and hold it
>> there..
>> w/ about 17inch MAP. Used to go from 2000 asl to 12000 and back
to
>> 2000[surface] in 18 minutes.. The other way to do it was Vne and
no
>> flaps
>> and 17"MAP.. but in the summer bump's you'd lose sight of the
wing
>> tip's
>> during the bumps.. not a really secure feeling.. We got paid by
the
>> trip so
>> the faster the better.. :-) 27 trips in 1 day was enough to wear
ya out
>>
>> Jarrett
>>
>>
>> Why do you think they are not approved for slips Jarrett?
>> Was it the pitch buck or was it some other reason?
>>
>> I have always known that but it does not bother me to do them
>> anyway in my angled tail 182. As far as I can tell it does not
>> pitch buck like a 172. Maybe I am doing them wrong :)
>>
>> Of course you can run out of gas as all the gas tends to
>> flow to the lower wing when the tank selector is on both.
>> But then again you are landing usually so you should not care
>> if the engine quits. Never the less I set the selector to the
>> upper wing. There is a scenario where someone may pull out on
>> the runway at the last minute.
>>
>> Paul Lamar ...No rotor no motor.
>
>
> I really couldn't say Paul, it could be for either of those
reasons, I
> would tend to think that most people wouldn't do a slip for
minutes on
> end
> so the fuel starvation is then less of a concern, the instability
in
> pitch
> is a bit more of an attention getter. Cessna's are ok for
slipping w/ the
> flap's up so... most likely its the pitch issue w/ using
flaps. [ I'm
> guessin']
>
> Jarrett
>
>
>
> I have always been curious about this and I never found anybody
> that knew the reason. A lot of new instructors get freaked
> out when they do my bi annuals and I slip it in :)
>
> Paul Lamar ...No rotor no motor.
I think the Cessna prohibition against slips with flaps is related to
the Fowler flap mechanism not being designed for the lateral
aerodynamic
load created by a slip. I was unaware of the pitch instability issue.
I suppose I've not slipped my '69 C150 J through enough altitude to
experience the instability.
Aubrey
I used to slip my C150M with partial flaps all the time. We have a
couple of fields out here with power lines & I made a habit of dragging
in high & then slipping down to short final. Couldn't use full flaps up
here in our DAs, so I can't comment on behavior at 40-degrees, but at
30-degrees it was tame as you could ever ask for -- as Jerry mentioned
in his response. Pitch was rock-stable for me.
Mark Supinski
The 172R POH states that
"Steep slips should be avoided with flap settings greater than 20 deg. due
to the tendancy of the elevator to oscillate under certain combinations of
airspeed, slip angle, and CG loading."
They are not prohibited, just discouraged.
I seem to remember the nose bobbing up and down a little is all.
Earlier models may be different.
The 152s don't have this issue for some reason. I'm guessing elevator size
among other things.
Ron Freier
Vision 2+2 13B Turbo
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