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Purpose of Flaperon Droop?

J

JohnF

Well Known Member
In simple terms, what is the purpose of the PAP call-out of right flaperon droop when then left one is held even with the wing tip? Also, what, if any, would be the result of no droop, just equal alignment with both of the wing tips with the stick centered?
 
No droop

what, if any, would be the result of no droop
Click to expand...
The plane might go faster and bust the 120 knot speed limit! :D
They have you lock the controls with sticks centered and flaperons flush with the wings, then drill and bolt everything together. What if there is not enough play in the control linkage to droop a flaperon 1/4"?
Joe
 
I bet in flight...

JohnF said:
In simple terms, what is the purpose of the PAP call-out of right flaperon droop when then left one is held even with the wing tip? Also, what, if any, would be the result of no droop, just equal alignment with both of the wing tips with the stick centered?
Click to expand...

...the upward force on the flaperons will move both of them to a neutral position.
 
As a wannabe builder, this is a little confusing to me. Would it not then be the same if you held the RIGHT one neutral and looked for a droop on the left one?
Again thinking outside the box, would it not then make more sense to hold BOTH of them up to simulate air forces and adjust for even up position? It looks like you are maybe pre judging the amount of play in the linkage? (which would be a variable)
 
If one is level and the other is 1/4 inch down, they will both end up being 1/8 down if there's no slack. So I beg to disagree with Scott.

Is the point of all this to ensure the play in the system is of the order of 1/8 inch per side? I've just spent ages adjusting things to get thst 1/8 inch per side.

Cheers...Keith_who_has_spent_far_too_long_on_this
 
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The point is

When you drilled the torque tubes, any play was not accounted for. Adjusting them down later is to make up for the play. When flying, the up pressure brings them back up to 'flush' with the wing ends.

John Bender
 
Since there seems to be so much confusion about this subject, I will try and clear this up. You can choose to believe a different reason if you want, but this is why they are drooped.

There is elasticity in the flaperon control system. If you lock the position of one flaperon, you can put pressure on the bottom of the other one and lift it approx. 1/8". This also happens in flight (remember basic flight physics- - - there is higher pressure on the bottom of the wing).
The droop is to compensate for this to make the flaperons align in trail while in flight.

The procedure in the PAP is just a check. It is not an adjustment procedure. All it means is that if the flaperons are rigged properly (each one drooped approx. 1/8"), if you put a clap on one so that it aligns with the wing tip, you should measure about a 1/4" of down deflection on the other flaperon.
It never says adjust one so that it is 1/4" down with the other at neutral. If you do this, the stick will not be centered in straight and level flight.
If the system is rigged properly, it technically wouldn't matter which one you clamped into alignment with the wing tip, the other should be displaced down 1/4".

That is the reason.
 
rvbuilder2002 said:
Since there seems to be so much confusion about this subject, I will try and clear this up. You can choose to believe a different reason if you want, but this is why they are drooped.

There is elasticity in the flaperon control system. If you lock the position of one flaperon, you can put pressure on the bottom of the other one and lift it approx. 1/8". This also happens in flight (remember basic flight physics- - - there is higher pressure on the bottom of the wing).
The droop is to compensate for this to make the flaperons align in trail while in flight.

The procedure in the PAP is just a check. It is not an adjustment procedure. All it means is that if the flaperons are rigged properly (each one drooped approx. 1/8"), if you put a clap on one so that it aligns with the wing tip, you should measure about a 1/4" of down deflection on the other flaperon.
It never says adjust one so that it is 1/4" down with the other at neutral. If you do this, the stick will not be centered in straight and level flight.
If the system is rigged properly, it technically wouldn't matter which one you clamped into alignment with the wing tip, the other should be displaced down 1/4".

That is the reason.
Click to expand...

Scott has this right

delta = Deflection P = Load E = Modulus of Elasticity
 
BUT, dial in about 1/2 half of what the PAP suggests! Will be adjusting mine during the 1st conditional inspection.
 
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