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Flap mount sequence

JDA_BTR

Well Known Member
I've got the wings built to the point of installing the lower skins and if I blindly follow the instruction sequence and install the skin then the flaps won't be setup correctly because the hinge hasn't been set yet.

I think that I need to build the flaps, locate the hinge, and then do the lower skin after the wing-side of the flap hinge is prepared.

I was curious what the best way is to get the flap lined up for the hinge drilling? I know the edge has to match the aileron but how is that setup the easiest way? Looked to me to put the wing on a table top down, rig the aileron for neutral, space the flap off the aileron with a 1/4 board, and align the edge with a long straightedge (or tight string?).

After match-drilling the hinge I'll countersink the flap fairing to take the dimpled skin.

Any tips?
 
DWG 12A, WING MISCELLANEOUS

upper left corner, view C-C

shows how to allign the aileron.

once that is done, continue the way you already said.

1/4"board for spacing between aoleron and flap, long straight edge,...…
 
Picture added

DWG 12A, WING MISCELLANEOUS
 

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Consider the optional hinge installation where two center tabs are removed. This allows you to have two hinge pins installed from the center of the flaps.
 
Yes the centered hinge solution looks good. Will probably add a nut plate to hold a pair of hinge eyes to hold the ends. Did that on my 14 wing tip hinges and it worked well.
 
Yes the centered hinge solution looks good. Will probably add a nut plate to hold a pair of hinge eyes to hold the ends. Did that on my 14 wing tip hinges and it worked well.

A single hole in the flap brace for each pin allows for safety wiring each one in place. Worked well on mine.
 
I tried both the “remove a couple of hinge eyes” and the hole in the aileron bracket. The hole is the aileron bracket is by far a better way to go.

Carl
 
Why is that Carl? What diam did you drill the hole? Does it make removing the flaps later tough?
 
Can I breathe new life into this thread? Ailerons aligned and half the flap hinge is already riveted to the wing. So, all I have to do is align the flaps with the already aligned ailerons and somehow hold all of that still, so I can capture that position and rivet the other half of the hinge to the flap brace? And, then there is the mysterious comment about how to remove or insert the flap hinge rod?
 
It seems you are getting bent around the axle - it is more straitgh forward.

The flap hinge, at his point, is not about alignment. The objective is to get the trailing edge of the flap at about the same distance from the wing leading edge as the trailing edge of the aileron. The prints have the dimension of the hinge placement, but checking with the aileron is a good idea. Once done, then drill the flap hinge per the directions.
After the hinge is drilled, run the hinge pin in so that it hits the aileron hinge bracket. Mark the point - this is where you drill the hole to put the hinge in when mounting the flap after the wings on the plane. The last step is to drill a small hole in the most inboard flap hinge eyelet perhaps 1/4” in from the end. Insert a piece of safety wire in the hole. This is the stop that prevents the pin from moving out of the hinge in the inboard direction. Put a self tapping screw in the aileron hole as the pin stop for the outboard direction.

After the wings are on the plane, the next thing to do is rig the flaps so that they are fully up (as in faired with the bottom of the fuselage). Verify both flaps are exactly the same in the full up position using a straight edge along the top of the wings. Then rig the ailerons so that the trailing edged line up with the trailing edges of the flaps. Have a couple of other builders check your rigging. I find a lot of RV heavy wings are caused by poor rigging.

After the flaps and ailerons are rigged on the plane, then you have fit the wingtip. Do not try to fit the wingtips before this.

Carl
 
After the wings are on the plane, the next thing to do is rig the flaps so that they are fully up (as in faired with the bottom of the fuselage). Verify both flaps are exactly the same in the full up position using a straight edge along the top of the wings. Then rig the ailerons so that the trailing edged line up with the trailing edges of the flaps. Have a couple of other builders check your rigging. I find a lot of RV heavy wings are caused by poor rigging.
Carl

Carl,
That is not the current way the 8/8A plans and manual align the ailerons and flaps. After the wing incidence is set and the rear spar attachment is drilled, the ailerons are set first, using the end wing rib tooling holes and a fixture to align the aileron trailing edge with this reference line (RV-8 DWG-12A). Then the flaps are aligned with the ailerons. The flap trailing edges will end up slightly lower than the fuselage belly.
 
Carl,
That is not the current way the 8/8A plans and manual align the ailerons and flaps. After the wing incidence is set and the rear spar attachment is drilled, the ailerons are set first, using the end wing rib tooling holes and a fixture to align the aileron trailing edge with this reference line (RV-8 DWG-12A). Then the flaps are aligned with the ailerons. The flap trailing edges will end up slightly lower than the fuselage belly.

Yep - that is what it says. While this tooling hole approach is a good starting point (and should be done), I do not consider this accurate enough for final rigging. Do not let this “one and done” rigging set you up to ignore the flap(s) being full up (or for the RV-10 and RV-14 the flaps up against the rear spar). I’ve seen more than one RV with the flaps dragging and/or one higher than the other.

A straight edge measure control surfaces in multiple locations to will achieve the best results. It will also put a spotlight on aileron hinges not aligned - as in the aileron is too high/low WRT the wing and/or not parallel with the wing in height or aileron to skin gap. This is a major rigging issue that goes unnoticed until the builder goes chasing a heavy wing. Do these checks before even thinking about squeezing any trailing edge.

Carl
 
Thanks, Carl. Yes, I was hyperventilating about this, but getting away from the words and looking at the actual flaps/hinge/wing made several things clearer. Thanks for clarifying about the outer end and the hole drilled in aileron bracket for future hinge rod removal.
However, Just to ask the obvious, I'll be lining up the flaps with the outer end of the hinge, correct? The inboard end of the flaps and hinge go beyond the inner portion of the hinge brace. I assume that's intentional.
My flap brace has "relaxed" aft, so I'll be clecoing the bottom skin on to bring it into position. With the ends of the clecoes intruding toward the hinge, it may be a bit delicate to get the hinge in the exact place needed to make everything line up.

It's all becoming clear to me now. Thanks
 
You should not need clecos to hold things together here. If the skin is dimpled and the brace countersunk then you can clamp the hinge in place and the dimples will nest into the countersinks and keep the skin and brace aligned. Watch for edge distance on the hinge, there have been problems in the past!
 
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