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View Full Version : CFI Pop Quiz #222 - Flapping

Chris Burgess
02-22-2006, 07:01 AM
Rotor blade flapping action is

A) an undesirable reaction to changes in airspeed and blade angle of attack.
B) an aerodynamic reaction to high speed flight and cannot be controlled by the pilot.
C) a design feature permitting continual changes in the rotor blade angle of attack, compensating for dissymmetry of lift.
chuter
02-22-2006, 07:55 AM
I think they want C.
KenSandyEggo
02-22-2006, 08:35 AM
I think "A."
Caribean_gyro
02-22-2006, 09:34 AM
C due to the disimetry of lift
chuckP
PW_Plack
02-22-2006, 12:14 PM
Ken, it's C. As in the "flapping hinges" in your J2's articulated rotorhead. A teetering rotor is designed specifically to allow flapping to resolve disymmetry of lift.

Flapping itself is not a negative. The bad experience we call "blade flap" is used to describe flapping which exceeds the mechanical limits of the teetering hinge.
Paul_Zurawski
02-22-2006, 12:26 PM
Gonna go with (C)
Aussie_Paul
02-22-2006, 01:19 PM
Rotor blade flapping action is

A) an undesirable reaction to changes in airspeed and blade angle of attack.
B) an aerodynamic reaction to high speed flight and cannot be controlled by the pilot.
C) a design feature permitting continual changes in the rotor blade angle of attack, compensating for dissymmetry of lift.

........I believe that the question should be "Rotor blade teetering action is" Then the answqer would be (C)

The gyro industry knows blade flapping as too much airspeed for the amount of rotor rpm.

Aussie Paul. :)
PW_Plack
02-22-2006, 01:58 PM
Aussie Paul,

Not all rotorblades teeter, even among gyroplanes. The question is properly framed. We need to learn correct terminology, not expect the rest of the world to adapt to our tiny market segment.
KenSandyEggo
02-22-2006, 09:36 PM
I'm gonna quit doing these things. I'm looking stupider than I really am.....or something like that.
Chris Burgess
02-23-2006, 04:10 AM
When I talk about blade flap to students, it is important to say "excessive" when we talk about the "bad" one. The most correct answer, Rotor blade flapping action is C) a design feature permitting continual changes in the rotor blade angle of attack, compensating for dissymmetry of lift. Reference FAA-H-8083-21, Chapter 3
Aussie_Paul
02-23-2006, 12:25 PM
I'm gonna quit doing these things. I'm looking stupider than I really am.....or something like that.

Ken, I thought that you were stupoid, now you have proven it!!!!!!:D Don't hit me mate!!!:eek:

Aussie Paul.:)