Airspeed white arc.

brien23

brien23

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Top of airspeed white arc going faster could cause structure damage. As you lower flaps a C-172 pitches down at what speed will the elevator not have enough up to pull out with full flaps down.
 
The initial lowering of flaps from 0 to 10 should cause you to pitch up slightly... It certainly does on every 172 I have flown. I would guess the elevator can overpower the flaps at most any speed that is still flying.
 
I thought it didn't have to do with running out of elevator but rather stress on the control surface.

The pitching down just changes the attitude. The elevator should still have full authority.

Meaning, let go of the yoke with full flaps and elev. neutral and plane will pitch down but it is not diving, the flaps allow the plane to fly at a nose down angel but the plane is not diving at the ground, it is just flying level in a more nose down attitude.

I could be way off but I don't think the flaps could cause you to run out of elevator.
 
DesertNomad said:
The initial lowering of flaps from 0 to 10 should cause you to pitch up slightly... It certainly does on every 172 I have flown. I would guess the elevator can overpower the flaps at most any speed that is still flying.
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As flaps go down the center of lift moves aft.
 
brien23 said:
Top of airspeed white arc going faster could cause structure damage. As you lower flaps a C-172 pitches down at what speed will the elevator not have enough up to pull out with full flaps down.
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Can you ask that question in English? :confused:
 
Obviously someone - either the student or the teacher or both - slept through ground school.
I am seeing many new pilots that seem to have little grasp of the physics of flight and the reasons for the various markings and limitations of an airframe.

I partly blame it on the lack of 'hanging out at the airport' time. With airports since 9/11 being sterile islands of the HSA with keycards and escorts and 'authorized personnel only' knowledge that used to be gained by osmosis does not happen now.
 
brien23 said:
Top of airspeed white arc going faster could cause structure damage.
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...if you extend flaps at that speed or exceed that speed with flaps extended. That said, many airplanes still allow partial extension of flaps above the top of the white arc, e.g., many 172's allow 10 degrees of flap at 110 KIAS or below, but no more until below 85 KIAS.

As you lower flaps a C-172 pitches down at what speed will the elevator not have enough up to pull out with full flaps down.
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The elevator system on a 172 can handle pitch during full flap extension at any speed from the top of the white arc down to flaps-down stall speed. Above the top of the white arc, full flap extension risks structural failure of one or both flaps, and then there's no guarantee of what the flight controls will be able to do. But the determination of Vfe (maximum flap extension/extended speed, i.e., top of the white arc) is strictly an issue of flap structural strength, not control authority.
 
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The "elevator authority" thing defies logic. The more speed the MORE responsive the elevator is. Further a 172 doesn't "pitch down" when you extend the flaps. It pitches UP. If you've ever flown one of the older ones with the "johnson bar" flaps you feel your self pushing forward on the wheel while pulling on the flap lever.
 
Ron Levy said:
..top of the white arc) is strictly an issue of flap structural strength, not control authority.
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The original question was at above the white arc with full flaps at what speed will control authority be a problem not the structural strength.
 
brien23 said:
The original question was at above the white arc with full flaps at what speed will control authority be a problem not the structural strength.
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It will not be a problem at any speed as long as no structural failure occurs. If one or both of the flaps fail, you're on your own, and there's no telling whether that might occur 1 knot or 50 knots above the top of the white arc.
 
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