Drilling flap torque tube

[AKKen07]

Question for you clever folks...
I have the wings on and am just about done mounting the flaps and ailerons. One of the next steps is going to be drilling that torque tube. I'm pretty anxious about it because I am not good at drilling accurately or straight on tubing, plus I'm not sure how to line everything up appropriately before I attempt to do so.
I know I want to drill the arms with the pushrod resting on the padding as if flaps are "up."
How do you locate the other end of the torque tube (the inboard "lever")? and keep it there for drilling? Do I need to install the rigging first? I can certainly reference the plans to see the position it should be in, but making that happen in 3D is more challenging.
How do you drill over your head into a tube freehand accurately? I fully accept that I might be a bit "special" but I had such a hard time with drilling the torque tubes for the trim tabs that I gave up and welded the buggers after drilling more wonky holes than I want to admit. Pretty sure I saved myself a few ounces with that "fix"... :P
Thank you in advance.

[N942VT]

I have no real trick for it but it helps that it doesn’t matter what degree the hole is drilled through the arm within reason nor does it matter that the two holes match exactly. So once you break through the arm you can adjust a little if needed to get back to center. The bit will tend to center itself on the back side of the tube. Center punch, drill under size and ream to final size. Get someone to hold the arm where you want it, clamp or tack it in place
Definitely rig the cable first, it’s pretty fussy where that arm needs to be.

[Mark Goldberg]

The position of the "arm" of the flap torque tube in the wing root is shown on the plans. You can see the angle of the arm as compared to the bottom skin for example. That is with the flap all the way up. The only variable is how far inboard or outboard you place the arm. There you mainly want to avoid interference with the wing rear spar attach end plates. Use the bigger cable shackles there where the flap cables attach to the arms. Even then occasionally there can be some interference but there is another trick or two that is possible to help - if needed. Mark

[AKKen07]

Thanks guys, appreciate it! We'll give her a go in a day or two.

[PaulSA]

I second rigging everything first - the angles and clearances are pretty critical. When you drill, use a smaller bit first (#30 or 40) and just drill one hole, one face and cleco it. Then you can complete the drill at your leisure when you get the wings off again for painting/transport.

[Bcone1381]

I'll add to what Mark wrote....I found the distance between my flap arm cable attach hole and the rear spar was another easy way to clock the arm IAW the plans. I found the clocking effects the position of the cable attach hardware in relation to the aft spar attach area. Below I attached the drawing in the Patrol Plans...which is drawn full size.

Mark also mentioned the inboard-outboard position of the arm.

The Flap Cable will go under the interface of Rear Wing Spar End Plates and the Fuselage attach fittings. These two form an upside-down VEE shape as viewed behind the wing looking forward. If I see myself as a speck of dirt sitting on the flap cable and I am riding between the last pulley and the flap arm, I will move back and down under this upside-down VEE as the flaps are pulled from zero to full.

You want the cable to have maximum clearance under the upside-down VEE. A mis-alignment results in the shackle contacting the End Plate or the Fuselage fitting when flaps are deployed. On my aircraft both of the two parts that form the upside-down VEE can be an issue, both are to be avoided, yet the clearance might be about 1/4 inch when positioned ideally, if I recall correctly.

Screen Shot 2021-08-30 at 9.32.21 AM.png

[whee]

I like how Brooks explained it because my thinking was the same.

I measured off the rear spar to set the arm position then actually clocked it a bit further forward and line up the cable with the peak of the V.

[AKKen07]

Thanks guys - and great help Brooks. I started trying to figure out the wing root rigging today. It sure is a pain, one of the more frustrating puzzles so far. Besides clearing that upside-down "V" I have interference at the other end which appears to be just drawn into the design... A pretty odd thing to find if you ask me. I'll include a picture. No matter what hardware I put here it will hit the flange of this arm. So I guess I have to take the wings off and cut away the flange enough to clear the shackle or whatever. I tried several things to get around it and nothing worked without mucking up the clearance at the other end.
flap arm interference.png

[marcusofcotton]

... No matter what hardware I put here it will hit the flange of this arm. So I guess I have to take the wings off and cut away the flange enough to clear the shackle or whatever...

I'd guess a few minutes with a carbide burr in a die grinder would make quick work of taking down that flange without pulling the wings.

[AKKen07]

Might do that. Thanks!

[AKKen07]

I DID do that - it worked beautifully. Thanks for the idea - I didn't know that little tool existed and I love it! Thank you

[Bcone1381]

Thanks guys - and great help Brooks. I started trying to figure out the wing root rigging today. It sure is a pain, one of the more frustrating puzzles so far. Besides clearing that upside-down "V" I have interference at the other end which appears to be just drawn into the design... A pretty odd thing to find if you ask me. I'll include a picture. No matter what hardware I put here it will hit the flange of this arm. So I guess I have to take the wings off and cut away the flange enough to clear the shackle or whatever. I tried several things to get around it and nothing worked without mucking up the clearance at the other end.

Ken;

What size shackle are you using? Mark's build manual calls for an upsized shackle to avoid contact with the flap arm. This is not intuitive. Let me seeeee........oh, there it is......

You want the AN115-32 shackle for 5/32" cable, for it is larger than the AN115-21 for 1/8" cable.

The -32 shackle's larger size should miss clear the flap arm. The smaller -21 shackle will contact the flap arm. The -32 shackle is fabricated to use a .250" diameter fastener, but I believe your four place flap arm uses a 3/16" fastener to secure the shackle to the arm. So the -32 shackle will require a bushing at each end by slicing a thin section of .250 x .028 4130 steel tubing.

[whee]

Thanks guys - and great help Brooks. I started trying to figure out the wing root rigging today. It sure is a pain, one of the more frustrating puzzles so far. Besides clearing that upside-down "V" I have interference at the other end which appears to be just drawn into the design... A pretty odd thing to find if you ask me. I'll include a picture. No matter what hardware I put here it will hit the flange of this arm. So I guess I have to take the wings off and cut away the flange enough to clear the shackle or whatever. I tried several things to get around it and nothing worked without mucking up the clearance at the other end.
flap arm interference.png

Notice the flange on each side of the arm are not the same, one stops further from the end where the cable attaches. Confirm you have them them in the correct wing. Mine were installed in the wrong wing so I had to pull them, weld the holes, reinstall in the correct wing and redrill. Depending on how you finished the wing root area of the fuselage this work can be done with the wings on.

[AKKen07]

Thanks for the ideas. I checked the things you guys mentioned and all was per drawings and recommendations with no luck. After making sure everything was correct I did cut down on the flange. It came from the factory a little longer than the plans indicated but I cut it down further still. About 1/4" past the plans. Looks like this will do the job, then once I get my custom cable from ACS I'll try to clear the wing root the way Rob and Paul have done. No drilling until then... also need the wings off to figure out why one torque tube is sticking really bad before I can get the rigging right.

[Nev]

Ken, I just drilled my torque tubes yesterday. Just a thought, I removed the torque tube first and sanded the paint off where it runs through the bushings. This made a huge difference to freeing them up, especially after I put some oil on the bushings (mountain bike chain oil ).

[AKKen07]

Good call Nev, thanks! I was thinking something like that would do the trick - just have to wait till I get the wings off again. Chain oil is a good idea too - might try that!

[Chewie]

I'd like to tack on a question to this thread regarding the inboard Patrol flap levers. Which way are the flanges supposed to face? The top right corner of Sheet 9 shows the lever in assembly with flanges facing outboard, and this is how Russ Erb and Eric Newton show it on the 4 place. But the detail views on the bottom left corner Sheet 9 and on sheet 15 seem to show the flanges facing the fuselage, based on the convention that we're looking at the left wing for "make left and right" views.

Top Right Sheet 9.JPGBottom Left Sheet 9.JPGTop Left Sheet 15.JPG

[Bcone1381]

The first photo is of the Five at OSH this year. The second is my Patrol.
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