Drilling aileron counterbalance tube

My first attempt at drilling the two rib holes into the stainless steel counterbalance tube did not work as well as I hoped. After following Van's directions, I ended up with warp in my aileron spar, due almost undoubtedly to the fact that the holes of one end of the tube did not align with the two on the other end--I think one set of holes were pretty much aligned, the other set not so aligned.

Fortunately, I can probably just abandon the bad holes (notice them at the top of the picture), rotate the tube slightly and redrill two new holes on each end. This time I plan to mark my hole locations with the spar clamped to the work bench on each end (which I did not do the first time). Are there any other tricks or suggestions anyone might have that would help make sure my holes end up lined up from one end to the other and leave my aileron spar warp free?



Thanks,
Steve

alpinelakespilot2000 said:

My first attempt at drilling the two rib holes into the stainless steel counterbalance tube did not work as well as I hoped. After following Van's directions, I ended up with warp in my aileron spar, due almost undoubtedly to the fact that the holes of one end of the tube did not align with the two on the other end--I think one set of holes were pretty much aligned, the other set not so aligned.

Fortunately, I can probably just abandon the bad holes (notice them at the top of the picture), rotate the tube slightly and redrill two new holes on each end. This time I plan to mark my hole locations with the spar clamped to the work bench on each end (which I did not do the first time). Are there any other tricks or suggestions anyone might have that would help make sure my holes end up lined up from one end to the other and leave my aileron spar warp free?

Thanks,
Steve

Click to expand...

Steve, I had the same problem... my notes say:

"A close up of the aileron set-up used to align the counterweight tube prior to drilling. This is according to instructions, but may not result in an accurate alignment of the counterweight to ribs. A better way is to drill one end (both holes), then lay spar/rib assembly flush on a flat table and mark and drill the other end of the tube. "

Vern Little RV-9A

http://www3.telus.net/aviation/flying/RV-9A/photos/Wings/Aileron_photos.html

Here is what I did...

Put the thing together, with the SS CB pipe inside the leading edge, cleco it all together just as it will be when you are flying. With the drill, mark each hole using the skin to line everything up. Take it appart and drill the holes, then put it back together and you are done.

Hope that helps.

N941WR said:

Put the thing together, with the SS CB pipe inside the leading edge, cleco it all together just as it will be when you are flying. With the drill, mark each hole using the skin to line everything up. Take it appart and drill the holes, then put it back together and you are done.

Hope that helps.

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Thanks Bill.

Actually what I was referring to are the two holes at each end that attach the nose ribs to the tube (in my picture above, they are the holes directly above the clamp and underneath the tube). Getting them marked is really difficult because one of the flanges of the ribs is under the tube--it's really hard to get an accurate mark on the underside flange. Definitely I'll use your method to drill the span of holes that attach the LE skin to the tube. Does this clarify my problem at all? Am I still not understanding your solution?

It seems like Vern recognized my problem right away (thanks for letting me know I'm not alone Vern! I may try drilling both on one end first), though I'd still love to hear of any other ways to accurately drill those inboard- and outboard-most holes for the ribs.

Steve,

You are right, I did miss read your post.

Have you bought a right angle drill/tight fit drill kit yet? That will help a good bit and you WILL need one for the fuselage.

N941WR said:

Steve,

You are right, I did miss read your post.

Have you bought a right angle drill/tight fit drill kit yet? That will help a good bit and you WILL need one for the fuselage.

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C'mon Bill, can't you give me some advice that doesn't cost $57.25???! Actually that seems like a pretty good price. I think I am going to break down and get one. (Don't tell my wife: the cost of my tools are now upwards of $2500, I'm sure, and I don't even have a pnuematic squeezer! I told her they'd cost about $1700... oops).

Still working on how to mark that hole underneath the tube super-accurately though because it seems it would have to be dead-on on both ends of the tube to prevent warping. Did you start the hole while the tube was resting on the rib or did you just mark it and take it out to drill on the drill press? I"m probably worrying about this all too much, but it does seem kind of important.

Thanks again,

WOW!! Those pictures sure make me thankfull I went with the QB kit. Great work, you guys!! But it sure is a lot of work. Keep on bangin' out airplane parts. It will all be worth it.

Roberta

robertahegy said:

WOW!! Those pictures sure make me thankfull I went with the QB kit. Great work, you guys!! But it sure is a lot of work. Keep on bangin' out airplane parts. It will all be worth it.

Roberta

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You mean the quickbuilds also come with ailerons and flaps built?! I'm starting to think that if I ever do this again, QB wings are the way to go given that fuel tanks and other mildly important things like spars, flaps and ailerons come with it already done.

From what I've been able to tell, Roberta, the -7s ailerons are easier, particularly given the smaller counterbalance tube and folded trailing edge, so you may not have had to deal with this anyways, but who knows. If you really want to learn some new skills, fly to Washington and build mine! Thanks for the encouragement anyway.

alpinelakespilot2000 said:

C'mon Bill, can't you give me some advice that doesn't cost $57.25???!).

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Nope, I can't do it. You must be just like me, spending ~$200 a month on tools for the first year and a half. I'll tell you, I've got some very cool tools now and haven't had to buy a new one for, oh, a week or so.

alpinelakespilot2000 said:

Actually that seems like a pretty good price. I think I am going to break down and get one. (Don't tell my wife: the cost of my tools are now upwards of $2500, I'm sure, and I don't even have a pnuematic squeezer! I told her they'd cost about $1700... oops).

Click to expand...

Hahahahaha I still don't have a pneumatic squeezer. Me and Mr. Avery are toning my forearms.

alpinelakespilot2000 said:

Still working on how to mark that hole underneath the tube super-accurately though because it seems it would have to be dead-on on both ends of the tube to prevent warping. Did you start the hole while the tube was resting on the rib or did you just mark it and take it out to drill on the drill press? I"m probably worrying about this all too much, but it does seem kind of important.

Thanks again,

Click to expand...

If I remember correctly I assembled the thing marked them with the drill bit, took it apart and drilled them by hand but with a slow turning cordless drill. Spin the bit to fast and it doesn't seem to go through the SS.

Solution

I figured out a way to get the counterbalance tube drilled correctly. I looked back through the matronics archives and found a lot of cases of ailerons coming out warped. Some of that is likely due to the riveted trailing edge, but I would bet a lot of it also has to do with the two holes on each end of the counterbalance tube not matching each other. If they do not, it's not the heavy stainless steel tube that's going to twist, it's the rest of the aileron, so it does seem critical to drill the tube accurately. Here's what I did:



1. The "A" rib flanges (see picture) are easy to mark, because they are accessible. Thus, mark the hole location for the "A" flange on one side of the tube.
2. Take the tube out and drill that one hole--I found my holes drilled in the drill press using a v-block to hold the pipe resulted in MUCH better holes than trying to hand drill (the hand drilled ones were not near as round) and you do need to use a low speed drill and use some Boelube.
3. Once that first hole is drilled, cleco it back into the "A" flange and mark the other end of the pipe for its "A" flange. Drill as in #2 above.
4. Cleco tube back into both ribs and make sure that the spar and ribs still rests flush on a flat surface.
5. Marking hole "B" accurately is really tough because it is up underneath the tube. However, what I discovered is that hole "A" could be used in flange "B"--the lateral distances from one end to the other are the same. Thus, just rotate the tube, using the first two holes drilled in the pipe in flange B. Once they are clecoed in hole B, mark the location for the new "A" holes in ONE end. (Thus, you never need to try to mark the holes using the "B" flange.)
6. Drill the new "A" hole on one end, cleco it back onto the ribs (now one end of the pipe has two holes, the other end one hole). Make sure it all rests flush on a flat surface. If not perfectly flush, twist (slightly) the tube on the end that still needs one hole drilled into it until both ribs and spar ends rest flush on the surface. Mark the location for the fourth hole, drill.

Mine came out pretty much perfect here, but there is a lot of room to make a significant error that would almost assuredly lead to a warped aileron. Hope this helps someone else. Please let me know if I can clarify.

Steve