Control stick torque tube

[DBeaulieu]

What factor(s) determines the adjustment length of the rod end bearings which support the control stick torque tube? Is there a method/process for proper alignment in the vertical?

Dave (many questions...)

[Mark Goldberg]

If there is a dimension on the plans as to how the stick assy hangs below the floor tubing - use it. If not, you can scale it from the plans to get close to how far in to screw those two rod end bearings. Mark

[DBeaulieu]

Okay Mark, thanks. Didn't see any specs, but will look again and use scaling as a backup. Dave

[DBeaulieu]

Okay now...I used scaling off the plan in an attempt to arrange length of the rod end bearings the control torque tube hangs from. On the front bearing, I can't use the derived scale dimension due to interference with the rod for the lower boot cowl attachment and the torque tube. In fact, I have to thread the rod end as much as bearing thread and the check nut [thinner check nut (AN316] allows to barely get about 1mm of clearance from the boot cowl attachment rod. Considering going without a check nut to allow for a bit more clearance, but am concerned about long term vibration on the rod end threads over time. Also considering using a couple calibrated whacks with my 5# baby sledge hammer to bend the boot cowl attachment rod a bit for additional clearance. Another thought is to file away a bit of the threaded bushing which receives the bearing to gain a bit more clearance.

Based on another thread, itseems Bob is okay with no check nut on the idler arm bearing, but not sure or thrilled to go that route as well.

Open for discussion and thoughts on ways to proceed. All ideas cheerfully considered! Thanks. Dave

Control torque tube clearance.jpg

[Bcone1381]

I know of no design issue that drives the altitude of those rod end bearings except clearance and min. thread engagement.

I lowered mine for clearance around the bolt that holds it to the bearing, plus the shock strut bolts. Its tight there, but I would not get too concerned about matching yours to the drawing. I also validate adjustment of the boot cowl attach rod. DO whta you an to get the Jam Nut installed. I see no issue filing away some of that weld around the fitting either.

[spinningwrench]

IDLER ARM.jpg
This is how I did mine.

[Rollie]

I may be wrong, but I don't think you need a jam nut on these as the jam nut's function is to keep rod end bearing from turning in or out. With the torque tube installed, it is impossible for the rod end bearing to turn.

[DBeaulieu]

Rollie, agree with you on the restriction to turning, but concerns over time with continuous vibration and resulant thread wear without a jam nut to tighten thread contact up.

[marcusofcotton]

Rollie, agree with you on the restriction to turning, but concerns over time with continuous vibration and resulant thread wear without a jam nut to tighten thread contact up.

There have definitely been problems in some applications due to thread wear caused by not having jam nuts in place or having them loose.

[DBeaulieu]

Improved clearance of the torque tube by taking about 1/8" or so off the threaded tube which receives the shank of the rod end bearing. Have 5/32" of clearance and the jam nut, so will call that okay! Now to figure out what to do with the idler arm rod end that needs to swivel and hence no jam nut..

Control torque tube clearance improved.jpg Control torque tube clearance before improvement.jpg

[Bcone1381]

I was ok putting a joggle in each idler arm, then install a narrow bushing on each side of the rod end bearing. The bushing is fabricated in your shop using 4130 steel 1/4" x .028 tubing to take up the slop that the joggles produce. Giving more space with the joggles and centering the bearing on the bolt with the bushings will allow the ball to rotate until the bushed AN3 bolt hits the bearing body. I imagine right now your rod end body contacts the arm.

I think my stick moves about +/- 30 degrees with the joggled and bushed idler arm.

[DBeaulieu]

Brooks, I have about 37 degrees of lateral each side with the control stick. How did you end up doing the joggles? I am considering that versus modifying the idler arms...

Dave

[Mark Goldberg]

I found that just one washer on either side of the rod end bearing gave me more movement than what was spec'd on the plans. Mark

[Bcone1381]

Try the Washers Mark in past 11.1. I dont recall what I tried.....long time ago. With that being said, This is what I have on my set up.
Screenshot 2023-12-23 at 8.30.58 AM.png Screenshot 2023-12-23 at 8.31.10 AM.png


Maybe Arborite can step in and verify how he did his....I joggle my arms a long time ago. He did his LSA recently.

Look at the image below. It shows the piece after the joggle gets pressed into the piece.

If B is the arm then A is a piece of 1/4" stock....wood works, then place a second piece of 1/4" stock on top of "B". This three piece assembly then gets squeezed in a vice to form the slight joggle in the steel arm. A search for Joggle gives lots of information on doing them.
Screenshot 2023-12-23 at 8.41.31 AM.png

[arborite]

I think the LSA joint may be smaller, as i could only get +/-10 degrees out of the joint itself, so spacers weren’t going to work. ended up getting a high angle joint that has better than +/-22 degrees of rotation, which should be plenty. the stick without cables attached can flop over pretty far, but when you calculate the travel with the ailerons attached, it’s much less. the rod end is an Aurora HXAM-4T.

as for the joggle, i just put the idler arm in a vise with a spacer and tweaked it a bit. mostly eyeballed it and checked for proper fit.

[stinger]

The problem is this subject was brought up three years ago and the fix was noted . New builders don't get the information . I recall Mark actually had the factory joggle the bracket as Brooks picture shows but one does need two install a small washer on each side of the bearing to keep the rod end centered . There should NOT be any movement of the rod end threads , the jam nut should be secured allowing only the bearing to do its job . Stinger

[arborite]

Even with washers, mine wasn’t enough. as noted above, the rod end by itself with no constraints only moves +/- 10 degrees, which is not enough for me. I needed a wider angle bearing to make it suit. Attached is the rod end spec, which I measured to confirm. This rod end has a small shoulder on it that prevents the ball from rotating beyond 10 degrees. joints without the shoulder may travel further.

IMG_0711.jpg
IMG_0754.jpg