Control assembly mounting

Pbruce

Pbruce

Member, Patrol QB
Just trying to mount the control stick assembly. Good diagrams of assembly but can’t figure out how to hang it. Does anyone have a picture? Side view, top view, any view? Thx.
 
If you need more pictures let me know. Ed
 

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Thank you Ed. Perfect! I wonder, do you happen to have a shot of station F and rearward to the tail?
 
If you need more detail I may have a few pictures. Note the the push/pull rod coming out of the torque tube at station D has a bend in it. That means when the control stick is moved left to right the rod end at the bell crank at station F does not get a lock nut on it's threads or some are making sure the bell crank has enough clearance so the rod end ball can rotate through it's full travel. Hope this is helpful Ed
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I recall when I attached my control stick assemble to the fuselage the roll axis has some resistance. The distance of the threads between the two rod end bearings that received the assembly was a small fraction of an inch off. I can't imagine tehfactory getting that tolerance exactly nailed. So mine had some resistance in the roll axis. Well, a few calibrated gentle Whacks of a one pound plastic mallet moved the cross tube of the rear fitting so zero resistance was experienced.
 
Thanks guys. So far I think I’m good in the roll axis. However, one end of the pitch movement has some friction just before the hard stop. I’m still trying to figure out where and why exactly. The other end is smooth until it goes “clonk” against the hard stop.

Ed, thanks again for the photos. I may have to query you further on “no lock nut at station F”. I haven’t assembled all of station F and aft of it yet, but I don’t know how we can go without a locking nut anywhere on a control. I have research and more assembly to do to do before calling on you further. I’m using castlated nuts and cotter pins throughout the stick assembly because it seems that they are either required or prudent. I will check the FAA guidance on this again though. I’m a newb so I could easily be mistaken. Standing by to be corrected, with gratitude. Come to think of it, I haven’t actually installed the cotter pins on the nuts inside the tube either, so I could be in for some clearance issues yet. It’s pretty tight in there, particularly toward the bottom of the tube. Thanks again everyone for the help.
 
I guess I actually do have some tightness in roll. It seems to get stiffer toward the extremities, and is lighter near centre-stick. I’ll keep your experience in mind as I investigate and tweak. Thanks again. I’ve got the rod ends screwed in pretty much all the way into the frame. I wonder if lowering them would have any effect? Easier to affect a result with the mallet, it came to that I suppose, and obviously closer to the belly fabric.
 
Without the ailerons actually hooked up - it is hard to determine how much stick movement happens to get the spec'd aileron deflection. So the stick movement where you say things stiffen up some just might be outside the range of movement needed to move the ailerons the required amounts up and down. Mark
 
Mark is right. I am leaving my assembly until my wings are made and the cables connected to see if any adjustment is required. Ed
 
I can't stress enough that the rod end you are referring to must have a jam nut, one does NOT want the rod end rotating in the push pull rod threads. That is the worst thing one could do . Open the idler bell crank and allow the rod end to rotate freely without touching the sides . I don't normally speak of my experience but I have over fifty years of aircraft knowledge with A&P I&A tickets. Check with a EAA chapter Rep. and see what they think. Stinger
 
The jam nut on the push/pull rod end at the idler is Not a option , either build a wider one or spread the sides . I do not want to see a Bearhawk go down . Stinger
 

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Agreed...The jam nut needs to be there. One of the benefits is it locks the threads to prevent any "hammering" Also, I have found that the rod end housing can contact the washers and so I used 1/4-28 bushings instead. Not that hard to spread the idler to get the clearance needed. Collin
 
The resistance in my stick is so low that the stick tips over. Resistance at the extremes is something I would not worry about, because it will be limited later on in the build to comply with aileron deflection angles of +20/-16 degrees of movement that the plans stipulate.
 
After thinking about it I agree. When it is time for the final adjustments I will be making what ever bushings are needed so the locked rod end can rotate freely in the bell crank. Thanks stinger and Collin. Ed
 
Thanks everyone. Ok I’ve got rid of all the resistance except for a tiny bit at the very extremity of full back stick. I’m happy with it for now. When I set my elevator throw I can revisit this if it’s needed, which I doubt. I think Stinger is telling me to insure that there is a jam nut up against the pushrod on the shaft of the bearing rod-end. I have this. (1st pic) It’s a plain (thin) nut since this seems to be depicted on the plans. I see no reason why I couldn’t change it to a nylon locking nut for more security.

I don’t quite see why the extra width or looseness is desired in the fork though. Mine pinches the spherical part of both rod end bearings very tightly, but the bearings still work perfectly, since the outer part of the rod end does the moving around the fixed sphere. ( 2nd pic). Am I missing something?

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Pbruce said:
I don’t quite see why the extra width or looseness is desired in the fork though. Mine pinches the spherical part of both rod end bearings very tightly, but the bearings still work perfectly, since the outer part of the rod end does the moving around the fixed sphere. ( 2nd pic). Am I missing something?
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If it pinches the rod end bearing and you have a jam nut, thats not good. The rotation of the stick exceeds the rotation of the rod end bearing in this configuration.

This thread might help understand what we are talking about.
http://bearhawkforums.com/forum/bear...-stick-pushrod

A more lengthy response.......

The Control Stick’s Push-Rod connects to the idler arm with a rod end bearing. But there is insufficient room in the 7/16” fork for the .500’ wide bearing to fully swivel as roll inputs are commanded by the stick. As the stick is moved left/right, the rod end bearing also rotates until the bearing housing contacts the sides of the Idler Arm. Ideally, the rod bearing outer housing should not contact the idler arm as it swivels.

There are two ways to proceed. Some do not use a jam nut which allows the pushrod and rod end bearing to rotate freely when the stick is moved. This method requires annual lubrication of the threaded rod end/elevator push rod connection.

Others joggle the fork to create more space for the bearing to rotate. This joggle makes the fork wider to accommodate the bearing. We also placed a small bushing on each side of the bearing to secure the assemble tight with proper hardware and torque specs.

Here are notes I made for myself. To secure the rod end bearing to the lower idler fork, while allowing the bearing to fully swivel.
  1. Joggle the lower .750” of the idler arms out .125” each, opening it up to .750” in lieu of the snug fit on the rod end.
  2. Lock the rod end bearing to the control stick push tube with a Jam nut.
  3. Fabricate two bushings (1/4” x .028 x .120) to fit between the fork and the rod end bearing.
  4. Install the Rod End Bearing into the Idler Arm’s widen out lower fork, using the AN3-11A bolt , the two 1/4 bushings, and secure with proper hardware
You also may want to drill some lubrication holes above in the idler arm hinge mechanism above this rod end bearing.

The photo below shows a slight joggle in the lower fork and the bushings sandwiched between the fork and the bearing.
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Thank you everybody. Mark mentioned that I might have clearance issues between the fork and the rod end bearing. The odd thing is that the whole idler system works perfectly smoothly at all extremities and everywhere in between and I have got more roll movement than I’ll ever use. Come to think of it, Mark said they may have adjusted this at the factory, which could explain why mine seems to be working in spite of the fork being absolutely tight on the spherical bearing.

I could take it apart and open up the fork like in Brook’s picture, but since mine works as is, would I be accomplishing anything? On the one hand I hate to mess with success, while on the other, I absolutely do not want any degradation of the most critical element on the plane
 
We re-checked everything. We ARE going to open up the fork and put thick AN washers or bushings as spacers so that there is guaranteed clearance around that rod end bearing. Better safe than sorry. I really appreciate all the timely assistance. I look forward to being on the giving end of this arrangement one day rather than the receiving end.
 
We ended up widening the elevator pushrod fork significantly and putting small bushings in exactly as Brooks Cone showed in his picture. It turns out that where I thought I previously had complete freedom of movement, some of that was courtesy of the rod end moving inside the pushrod because I failed to tighten the jamb nut on. Inserting washers allowed the spherical bearing to touch them, so we went to bushings like Brooks did to insure that we would have complete freedom of aileron movement. Thanks again to everyone who forecast the issues and provided the solution.
 
I notice in Brook’s picture that he used castlated nuts. I considered that this bolt and nut was not “subject to rotation” and I used a nylon locking nut. Am I wrong? Is a castellated nut required or more appropriate, or is it discretionary?
 
I think AC43.13 agrees with you. It's not subject to rotation because the bearing rotates and a nylon lock nut is sufficient. The castellated nut is easier to preflight though. Same goes for ailerons and flaps.
 
I have a full exploded view assembly drawing of the assembly I can send you with all parts called out. My .pdf drawings don't post very well to this web site as you will want a much larger view. Send me a private message or directly at spinningwrench@me.com.
 
Good point about the inspection, Brooks. PM sent, Mr Wrench. Thanks all.
 
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I came across this today when assembling the control stick and pushrods....(just at the end of my first week or so building a QB Patrol SP, so early days!)... I wasn't happy that the spherical bearing was hitting the bellcrank and needed the bearing to move in the nut threads so I machined two 2.5mm spacers and opened up the fork a little. Yet even after doing that, it still only allows the rear joystick to move side to side within about 1" either side of the front seat frame as a reference point. The drawings aren't much help either, not very clear, and I'd interpret them as needing the screw threads to move in the absence of a lock nut. Perhaps it will be within movement limits when I eventually get it all rigged up, but its the first thing I haven't liked, these are some of the little bits that could kill you no matter how good you are if they let go. I might get little more throw if I chamfer those spacers a little.

Any Patrol pilots know the rough side to side travel of the joystick needed?

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I did the stack up on the LSA and came up with about 13.5 degrees each side of center. My supplied bearing had a shoulder limiting travel to 10 degrees each side, so I found a high angle bearing (+/- 22 degrees) and replaced it. works fine now. washers did not work on mine since the bearing itself had shoulders limiting travel.
 
I had the exact same concern so I took a digital inclinometer to Oshkosh with me last year and measured the stick travel on Mark's Patrol that was displayed in the booth. I don't remember what the angle of movement was, but it was just inside of what the rod bearing on my LSA was giving me. I'm hopeful that the LSA doesn't require any more stick movement than Mark's Patrol did, but won't know for sure until I have everything rigged up. I also had to put some spacers on each side of the rod bearing in order to utilize it's full amount of motion/misalignment.
 
I used the math method. aileron max angular travel is published, and the various bellcranks and levers are on the drawings. pretty easy to calculate. the rod end angular data is available on the web, and i verified my joint was to spec. it was spot on +/- 10 degrees. I don’t have Patrol data, though. your heim joint is bigger than the LSA. Google the part number and you’ll find it.
 
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David Swartzendruber said:
I'm wondering how you determined that the Patrol heim joint is bigger than the LSA. Was that based on looking at the picture posted above by paulodonnell?
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Mark sent me the Patrol joint by mistake. It was a bigger thread and wouldn’t fit the LSA, so he switched it with me.
 
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