flyenforfun

flyenforfun

Well Known Member
I wanted to post this question on here as a second opinion.

I am having a problem with my flight controls now that I have the ailerons done and the aileron stops in. My first problem is with the rod end on the forward end of the pushrod that goes from the aft stick to the bellcrank (I know, confusing). When I move the sticks to full left and right aileron deflection, this rod end (the one that rocks left and right) contacts the sides of the stick weldment. I will attach a picture to help. It doesnt seem to hinder the movement of the controls, but I think I feel a drag on them when I move the stick forward and back with full aileron deflection in. This rod end just has the small spacers on each side, part number 5702-75-060, per the plans. It seems when the bolt is tightened down, the stick weldment squeezes together slightly. Has anyone else noticed this? Can I add more spacers? The picture below is of the rod end in question with the stick pushed to full aileron deflection.

ct1.jpg


My second problem is at the aft end of this same rod. With the stick at full down (forward), the bottom of the bell crank is pushed all the way back as it should. At this position, the Y of the bell crank contacts the top sides of the rod end. This also doesnt seem like a good situation. Is there anything that can be done here? My thought was to shorten both of the elevator pushrods to make the angle of the bellcrank at full down elevator not so extreme. Here is a picture at full down, its hard to see but the bellcrank is touching the rod end here.

ct2.jpg


Any help is appreciated, I want to solve this issue tonight and move on. Thanks everyone.
 
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I am having a problem with my flight controls now that I have the ailerons done and the aileron stops in. My first problem is with the rod end on the forward end of the pushrod that goes from the aft stick to the bellcrank (I know, confusing). When I move the sticks to full left and right aileron deflection, this rod end (the one that rocks left and right) contacts the sides of the stick weldment. I will attach a picture to help. It doesnt seem to hinder the movement of the controls, but I think I feel a drag on them when I move the stick forward and back with full aileron deflection in. This rod end just has the small spacers on each side, part number 5702-75-060, per the plans.

If it touches, but the rod can still be rotated a bit by hand (ie no solid binding) then it is OK.

If the rod is tight at full travel then a spacer should be OK, even a thin AN960 washer next to the bellcrank ear.
 
Solid binding on the front, no play at full aileron deflection. I don't think a washer up there would work, that's why it has the small spacers in there per the plans. It's so the stick can rock and the rod end won't hit the sides. At least that was the intent.
 
flyenforfun said:
Solid binding on the front, no play at full aileron deflection. I don't think a washer up there would work, that's why it has the small spacers in there per the plans. It's so the stick can rock and the rod end won't hit the sides. At least that was the intent.
Click to expand...

Correct next to the bearing, but it should be OK next to the bellcrank with the small diam. spacer inboard, especially if it is getting "sucked in" as you tighten the nut.

Try it...:)
 
az_gila said:
Correct next to the bearing, but it should be OK next to the bellcrank with the small diam. spacer inboard, especially if it is getting "sucked in" as you tighten the nut.

Try it...:)
Click to expand...

Will do. Any ideas for the aft end? Try spacers there as well?
 
Matt,

You've indicated that the aileron stops are installed (no indication regarding elevator stops). What are the control deflections (in degrees) that they were installed to?

The possibility exists that the travel limits are exceeded or that interference is encountered due to a bit too much travel within the spec but towards the max end of the limits. See Section 15, Page 2 for control surface limit specs.

Only the minimum limits are required for safe operation. If you are at the max limits and getting contact, then try stopping them down to the mins and see if that fixes your problem. The only time you will use these extreme angles is taxiing during high wind conditions and never in flight... :eek: Secondary reasons for the stops are to keep the controls from banging over center in high winds without control surface locks installed causing damage to the system.
 
Joe Blank said:
Matt,

You've indicated that the aileron stops are installed (no indication regarding elevator stops). What are the control deflections (in degrees) that they were installed to?

The possibility exists that the travel limits are exceeded or that interference is encountered due to a bit too much travel within the spec but towards the max end of the limits. See Section 15, Page 2 for control surface limit specs.

Only the minimum limits are required for safe operation. If you are at the max limits and getting contact, then try stopping them down to the mins and see if that fixes your problem. The only time you will use these extreme angles is taxiing during high wind conditions and never in flight... :eek: Secondary reasons for the stops are to keep the controls from banging over center in high winds without control surface locks installed causing damage to the system.
Click to expand...

Our aileron travel is 30 degrees up and 16 degrees down. The limits I think were 25 to 32 degrees, so we are toward the high end. Id hate to change it now, I would have to drill out the stops and make new ones. If I have to I will, but maybe adding another spacer to spread apart the clevis on the bottom of the sticks would work?

Is there a downside to having 30 degrees of aileron other than this interference?
 
Matt,
You should never squeeze the steel by tightening the bolt. This pre-loads the metal and could eventually lead to fatigue and cracking; not as much in steel as aluminum but it could happen.

At the fwd end of the pushrod, I would add enough spacers or washers thick or thin so that when you tighten the bolt you are not deforming the weldment. You can buy more of those little spacers from Van's or make your own.

As Jason said, you mentioned the aileron stops but didn't say anything about the elevator stops. If the elevator stops are not installed, you may not even have a problem at the aft end. If they are installed, you can shorten the pushrod from the bellcrank to the elevator horns by threading in the rod end bearings. This may move the bottom end of the bell crank forward enough to where you might solve your dilemma. Also, you may need to add some washers/spacers if you are squeezing the bell crank ears with the bolt. As a side note, it looked like you had too many threads sticking past the nut on that bolt at the aft end of the pushrod. It will take some fiddling with the pushrod lengths to get your rigging just right. Don't take the Van's lengths for granted. They are very good approximations.

Jerry
RV-8 N84JE
Flying since 2007, 630 hrs
 
RV8Squaz said:
Matt,
You should never squeeze the steel by tightening the bolt. This pre-loads the metal and could eventually lead to fatigue and cracking; not as much in steel as aluminum but it could happen.

At the fwd end of the pushrod, I would add enough spacers or washers thick or thin so that when you tighten the bolt you are not deforming the weldment. You can buy more of those little spacers from Van's or make your own.

As Jason said, you mentioned the aileron stops but didn't say anything about the elevator stops. If the elevator stops are not installed, you may not even have a problem at the aft end. If they are installed, you can shorten the pushrod from the bellcrank to the elevator horns by threading in the rod end bearings. This may move the bottom end of the bell crank forward enough to where you might solve your dilemma. Also, you may need to add some washers/spacers if you are squeezing the bell crank ears with the bolt. As a side note, it looked like you had too many threads sticking past the nut on that bolt at the aft end of the pushrod. It will take some fiddling with the pushrod lengths to get your rigging just right. Don't take the Van's lengths for granted. They are very good approximations.

Jerry
RV-8 N84JE
Flying since 2007, 630 hrs
Click to expand...


The elevator stops are in place, and the degrees of travel for the elevator are good. I found out last night that the forward rod end bearing was not actually contacting the sides of the stick clevis. All of the binding was coming from the fuselage bellcrank contacting the aft rod end bearing. I put a thin washer on each side of the aft rod end bearing and that solved the problem completely. The bottom half of the bellcrank seems slightly spread now but I dont think it is a problem.
 
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