Ailerons Mounted and Push Rods Started

Time: 5 Hours

Now that the flaps are done I needed to start to assembly of the control surfaces onto the wings. First item was to mount the aileron bell cranks to the main spars. These bell cranks transfer the motion from the control stick in the fuselage 90° towards aft and the ailerons. They are powder coated steel and rotate around a brass bushing.

I first cleaned up the top and bottom of the bell crank tube where the bushing slides into. I then made a measurement on the tube and the bushing. Van’s calls for the bushing to be 1/64″ to 1/32″ longer than the bell crank tube. I used the scotch-brite whell and sand paper to get the length perfect. The bushings were a little tight inside the tube so I put the bushings in my drill press and turned it on while using some 400 grit sandpaper to hone them down until they slid nicely into the tubes.

Now I had to ream the inside diameter of the bushing to accept the 1/4″ bolt that goes through it. I just placed the bushing in my padded vise and used the reamer in my hand drill. It work pretty slick and the reamer just guides itself and is always centered.

I then assembled the bell crank pieces that will hold the push rod from the bell crank to the aileron. For this I had to cut a spacer from some stock that they give you.

I bolted the bell cranks back into position on the spars but didn’t torque them as I’m not sure if I will have to remove them later. I had originally torqued and sealed the 2 brackets that the bell crank bolts to on the spar back when I was working on the spar but relieved that I needed to remove them to install the bolts for the bell cranks.

20140514-173329.jpgWith those back on I moved my attention to mounting the ailerons. The ailerons are connected at 2 points on the wings, 1 bracket on each end. They use a combination of bolts, small washers, a large washer and a spacer similar to the bell cranks. The ailerons need a travel limiter, a physical stop so they don’t travel to far and cause damn he to them or the wing skins. Van’s has you make a small angle piece and rivet to the leading edge rib of the aileron. This angle will eventually hit the aileron bracket as it moves closer to its full travel. When it hits that’s the farthest the aileron will travel. My buddy Glen had a much better design that he used on his first RV-8 and repeated it on the one he is building now. What he did was transfer the contact point of the stop from the angle that’s on the rib to the spacer that’s in the bracket on the aileron. Clear as mud? Let me show you in pictures. Normally the stop would happen prior to the spacer hitting the bracket, around 1/8″ as you wouldn’t want just the spacer to be the limiter as it is just aluminum tubing. Glen used a piece of delrin tubing, it’s like plastic to me, and cut it to match the length of the spacer. He then reamed the inside so that the spacer would slide into it. Now when the aileron travels it will hit this new soft covering of the spacer and stop the movement. I first cut the space and made it perfect then I cut the delron tubing to match and reamed it to final size. I then assembled it all together as the plans show along with this new part.

That white spacer will come in contact with the bracket on the spar and stop it’s travel. Glen said this work great and it was super easy to make and install. You can see in several of this photos the various washers and how tight they are. I bought a set of washer wrenches to help with inserting these. They are just thin stainless steel wrenches that have various sized ends that hold washers by spring pressure. You then can slide them into place and when the bolt is inserted pull on the wrench and they pop off.

Again I didn’t torque any of these as I’m not sure if they will need to come off later. I then turned my attention to the push rods for the ailerons. There are 2 per side, one short steel one that goes from the bell crank to the aileron and a larger aluminum one that goes from the fuselage controls to the bell crank. I cut them with my pipe cutter to the length described on the plans. The shorter ones are cut to 23 13/16″ and the larger ones to 69 3/16″ for the RV-8. The plans give you call outs for several different models. Once cut I cleaned up the ends and the insides so that the rod ends would slide into them easily.

I repeated this process for the larger tubes which were a little easier to cut since they are aluminum.

The large rods get riveted to their ends by 6 rivets. 360° divided by 6 is 60° so I downloaded a protractor online and printed it so that I could create a template to make the rod ends.

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I used the template to mark all 4 ends of the 2 rods and grabbed my jig I bought from Harbor Freight to drill them. After I bolted the jig down and made all the required adjustments I drilled 3 holes and went completely through the rod making all 6 holes. I started with a #40 bit and used my #30 reamer to enlarge the holes.

I then moved on to the smaller rods in the same fashion. These just use 2 rivets per end at a 90° to each other. Since these are steel I sprayed a bunch of primer inside and rolled them around to get the entire inside covered.

That’s where I decided to call it a night. I should have a few hours in the Hangar tomorrow.

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