My bad. What the Cessna placard says is "Avoid slips with full flaps".N9149A wrote:There is NO limitation to slipping with flaps in a B model. Not a smart thing to do grant you but no limitation.
Placards and Decals
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
For those not familiar with the B-model's full-flap handling characteristics:
When the large "para-lift" flaps were originally installed and first test-flown, engineers feared the large flaps would create an unacceptibly large upwards pitching moment of the nose. But it was found that a down-wash from the large flaps impinged upon and somewhat blanked out the horizontal stabilizer and elevator. This tended to diminish effectiveness of the elevator and stabilizer, therefore a downwards pitiching moment very nearly countered the upward pitching induced by flap deployment. Happily, the downwash of the flaps almost exactly counteracts the upwards pitching of the nose when flaps are fully extended. Only a reasonable re-triming of the airplane is necessary to counteract the flap deployment.
However, the result is that if the airplane is simultaneously slipped, the fuselage's blanking of a portion of the down-wind stabilizer/elevator will allow the flap-downwash on the opposite, upwind side to severely and suddenly pitch the aircraft down (as the tail becomes severely blanked.) At low altitude such as on a short final (exactly when such a manuever might appear advantageous), it is possible that the sudden downward pitching moment cannot be arrested prior to hitting the ground. In especially severe cases, a tightly uncontrolled sprial not unlike a spin can develop. Therefore, in a B-model, it is advised not to slip the aircraft simultaneously with full flaps deployed.
When the large "para-lift" flaps were originally installed and first test-flown, engineers feared the large flaps would create an unacceptibly large upwards pitching moment of the nose. But it was found that a down-wash from the large flaps impinged upon and somewhat blanked out the horizontal stabilizer and elevator. This tended to diminish effectiveness of the elevator and stabilizer, therefore a downwards pitiching moment very nearly countered the upward pitching induced by flap deployment. Happily, the downwash of the flaps almost exactly counteracts the upwards pitching of the nose when flaps are fully extended. Only a reasonable re-triming of the airplane is necessary to counteract the flap deployment.
However, the result is that if the airplane is simultaneously slipped, the fuselage's blanking of a portion of the down-wind stabilizer/elevator will allow the flap-downwash on the opposite, upwind side to severely and suddenly pitch the aircraft down (as the tail becomes severely blanked.) At low altitude such as on a short final (exactly when such a manuever might appear advantageous), it is possible that the sudden downward pitching moment cannot be arrested prior to hitting the ground. In especially severe cases, a tightly uncontrolled sprial not unlike a spin can develop. Therefore, in a B-model, it is advised not to slip the aircraft simultaneously with full flaps deployed.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
I know what you mean by suggesting this Dick, ...and in the hands of test-pilots and those experienced with aerobatics, etc. ...or those with paid-up insurance with me as a beneficiary... might find the experience ...exhiliarating.blueldr wrote:In my non-humble opinion, every "B" model pilot should take his or her airplane to an altitude of at least 3000' AGL and see what this
"Don't slip with full flaps " thing is all about. After understanding what it's all about, they sure will never try it on final.
But the admonition to "avoid slips with full flaps"...means to avoid slips with full flaps. It does NOT say to avoid slips with full flaps below 3,000 feet AGL.
A full flap spin or spiral, entered into by a pilot not equipped to deal with the experience is not something that should be encouraged at any altitude....not just at low altitude. IMHO.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.