My plane is going in for a paint job in the near future. The way the flap hinges come together, the wing/flap hinge assembly comes close to rubbing together. Once painted, I?m worries about the inner and outer hinge parts rubbing against each other, messing up the new paint job. Would inserting washers As spacers between the hinge parts prevent any rubbing issues? The plans did not call for washers, so wondering if there is any negatives by doing this.
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Flap hinge question
- Thread starter togaflyer
- Start date
Bill Boyd
Well Known Member
One thing I've noticed
...lying on my back under the wings grinding away at the inboard edge of the flaps to let them bypass the fuselage sides and assume three degrees of reflex against the rear spar, is that a lot of the rubbing noises I feel and hear during this process come from the flap hinges themselves, not the interference of the flap with the fuselage. The contact of flap with fuselage pushes outward on the flap spanwise, and causes the hinges to flex enough that they rub like scissor blades past each other near the upper limits of travel. That kind of flex means that spacers will not solve your problem enough to protect the paint. More important would seem to be making sure there's enough relief between flap and fuselage that retraction does not shove the flaps outboard and cause the hinge arms to shear past each other.
I've only started this flap fitting process last night, but that's my take-away so far. The fitment effort has required complete sacrifice of the fiberglass closeout of the inboard flap rib that I so foolishly did last spring - that piece doesn't see slipstream in cruise so there is no drag reduction benefit to be had from plugging it flush. I failed to think that through beforehand.
...lying on my back under the wings grinding away at the inboard edge of the flaps to let them bypass the fuselage sides and assume three degrees of reflex against the rear spar, is that a lot of the rubbing noises I feel and hear during this process come from the flap hinges themselves, not the interference of the flap with the fuselage. The contact of flap with fuselage pushes outward on the flap spanwise, and causes the hinges to flex enough that they rub like scissor blades past each other near the upper limits of travel. That kind of flex means that spacers will not solve your problem enough to protect the paint. More important would seem to be making sure there's enough relief between flap and fuselage that retraction does not shove the flaps outboard and cause the hinge arms to shear past each other.
I've only started this flap fitting process last night, but that's my take-away so far. The fitment effort has required complete sacrifice of the fiberglass closeout of the inboard flap rib that I so foolishly did last spring - that piece doesn't see slipstream in cruise so there is no drag reduction benefit to be had from plugging it flush. I failed to think that through beforehand.
Electrogunner
Well Known Member
Flaps
The bronze bushings pressed into the hinge bracket sit proud of the surface I bit. Mine is painted and I have cycled the flaps multiple times programming setpoints. I have not noticed any rubbing at all on mine. Are you sure the brackets are not bent to one side or the other, it would not take much?
The bronze bushings pressed into the hinge bracket sit proud of the surface I bit. Mine is painted and I have cycled the flaps multiple times programming setpoints. I have not noticed any rubbing at all on mine. Are you sure the brackets are not bent to one side or the other, it would not take much?
Electrogunner
Well Known Member
Bushings
I don?t have my wing build manual here at home. But I?m pretty sure they are. I remember pressing them into the flap bracket holes. I used a socket on one side and a c clamp. The socket was needed because it gets pressed in so that both sides sit proud of the bracket. Actually I think they were even knurled so as to not spin once installed.
I don?t have my wing build manual here at home. But I?m pretty sure they are. I remember pressing them into the flap bracket holes. I used a socket on one side and a c clamp. The socket was needed because it gets pressed in so that both sides sit proud of the bracket. Actually I think they were even knurled so as to not spin once installed.
The bushings were provided in my kit and were bronze.
The Flap bushes supplied do stand proud so that basically stops any rubbing between the Flap and the Flap Hinge Bracket. Just something to consider not related to the question, If a small Ally plate is pop riveted on the bolt head side of the Flap Bracket to contact one or preferably more of the bolt flats/lands, then (because the bolt is captured and moves with the Flaps) the nut can be sinched up just right so as not to be to tight so the flaps grind on the bush or to loose to allow the flaps to start rotating on the bolt. Only a couple of pops are required but care needs to taken to position them so as not to interfere with the Flap Hinge Bracket through the Flap movement range. Also because the bolt is captured then there is no relative movement when the Flaps are operated. Cheers from Western Australia
