Flight control assemblies

[sonex892]

No worries and thanks Kip. Yes we are talking about removing the AN4 bolt in the joystick. Gee I wish I was as close to ACS as you. According to google I'm 11,850km from my nearest ACS outlet, thats direct.

The # 2 taper pin will be best with dimensions slightly larger than the 1/4" bolt. I'll order the #2 reamer, a pin or two and also some chromoly to remake the part if needed.

Steve 892

[142YX]

I also plan on using a #2 taper pin on my control sicks

[142YX]

Here is my idea for holding the control sticks straight while drilling the attachment. I used the same piece of MDF that i used to keep the horn assemblies parallel, additionally with a 3/16" think pice of scrap aluminum to make up for the difference in thickness




Here you can see the entire assembly clamped down to my (very clean, neat, and organized) work bench for easy drilling


This worked really well, the sticks came out pretty straight.


Also, i changed my mind from my above post. I just used #1 (AN386-1-8) taper pins for the control stick assemblies. I liked very much how the tail mixer came out which made me go in this direction, and i am convinced that a #1 is strong enough for this assembly (vice a #2). If i run into trouble with this in the future, I can always upsize to a #2 taper pin, or a -4 bolt. But i really like how they came out! There is absolutely zero slide to side slop in the stick attachment. The right stick only has the faintest amount of fore-aft slop, due to the stick tube being ever so slightly larger than the horn assembly.. it is so small i may do nothing about it.. but my gut tells me ill be doing something about that before to long. Had i used a bolt, i could tighten the crap out of it and likely eliminate the fore-aft slop.. but then i think the whole assembly would be more prone to side-to-side slop developing over time.

[falvarez]

Your setup looks great and the photos are quite helpful. I'm still a couple months away from installing my controls so I'm still a little unclear on the use of the taper pin...can you please help clarify? Is the pin used to help with clearance issues that would be present with a bolt? Or is it used to provide a more secure connection? Or something else?

Also, has anyone come up with a good way to make the passenger stick removable? If I can come up with a straight forward solution I would like to have the option of removing the stick as needed.

[142YX]

I used the taper pin because in my opinion, getting a "good tight fit" with a bolt is a very hard thing to do on tube-over-tube connections. If you simply use a 1/4" drill bit to drill a hole for an AN4 bolt.. you can be assured that it will wobble all over the place. AN4 bolts are all undersized, and vary +/- 1 or 2 thousandths of an inch.. most of the time when i measure them they are .247 - .248". For any structural, single shear AN4 bolt in the fuselage, i have been using a .248" reamer as my final operation to get a "good tight fit". But with the tube over tube assembly you have to cut two holes, one on each side of the tube. It has been my experience that if i am not doing this on a drill press.. the "first side" hole tends to get larger than the "back side hole" during the drilling process. If the hole gets even 1 or 2 thousandths of an inch larger than it should be.. there will be some slop/wobble which i do not want in the flight controls.


My description is pretty lousy.. so here is a picture of what i am trying to say



Now if you use an AN4 bolt, you can tighten the crap out of it, deforming everything slightly, and introducing friction between the inner and outer tube which might be enough to prevent any feel of slop.. but over time this assembly will have a greater potential to wear and get even more sloppy. I like the taper pin because you cant accidentally screw up the first hole, it is much easier to get a very tight fitting hole so that you do not have to rely on friction to eliminate slop.

Either way is probably fine, i have just convinced myself that this is better for me. Whatever way you choose to go, removing the passenger stick will only require removing the bolt/taper pin to get the stick off.. but it might be a good idea to make a collar of some kind to slide over the now exposed horn assembly to prevent the bushings from backing out. The control stick being on there holds everything together.

[falvarez]

Great description and diagram...that makes it quite clear. Just one more thing for me to consider now :)

[N111YX]

The taper pins took out all of my slop in the sticks. I could not stand having the stick move 1/8th inch before it did anything. The Waiex uses one in the mixer because flutter would be catastrophic. Looks good, Nick!

[fastj22]

I had the same issue as Kip. Too much slop.
I decided to just weld the pieces together since I have a MIG welder and know how to use it.

[142YX]

Tonight i started to rig my pitch control. The plans (this is for the Waiex only) say to place a 1/16" shim in between the stick frame and the spar box, and with the tail mixer fully forward drill the required bushing hole for the idler-to-mixer rod. I misunderstood what the plans meant by the 1/16" shim and did this at first.. it became obvious that it wouldn't work because the idler-to-mixer rod was in the wrong spot at the mixer end.



I didn't realize until this moment that the stick assembly goes over the spar when full forward. The instructions must have meant to put a 1/16" shim between the actual stick frame (and not like the forward most point of the stick like the above).



The problem that i ran into with this approach is that the entire assembly bottomed out at the idler before the stick frame was within 1/16" of the spar box. Because of this, i put a small shim in front of the idler and used this as my forward-most stick position for rigging. This made everything come out, from the best i can tell, correctly.



Now for the other problem i ran into. The ruder-vator push rods bottomed out by the spherical rod-ends hitting against their upper safety washer before the assembly moved all the way to the aft stop. Sorry about the bad photo.. it was very hard to get a picture of this:



You can see here more clearly what is bottoming out. In this photo, i have two standard washers above the spherical bearing and it still bottomed out (the prints call for only one). It took THREE washers above the spherical to get all the way to the aft stop, and i find this to be somewhat ridiculous.


Waiex builders, did you have this problem? what did you do?

[sonex892]

Now if you use an AN4 bolt, you can tighten the crap out of it, deforming everything slightly, and introducing friction between the inner and outer tube which might be enough to prevent any feel of slop..

Overtightening this bolt didnt work for me. It possibly just squashes and ovals the 3/4" tube making the situation worse. ie Bigger gap top and bottom between the tubes.
I understand that fore and aft slop may also still be a problem with one taper pin. I think the fore and aft play here could be eliminated by using 2 small taper pins one from the left and one from the right. Providing there is enough room of course :?: