Aileron control rod/bell crank rigging
Posted: Fri Mar 25, 2022 3:37 am
by Skippydiesel
Have just come from trying to rig my aileron control rods/bell crank angle. Phew! no easy task its very “tight” inside the wing.
I am hoping that some kind person (s) who has been down this particular track, can advise me of the easiest way to achieve the 25 degree bell crank angle, while connecting the control rod from it to the aileron (which must be held in the “neutral” position).
I should mention - the first builder of this aircraft has fitted ball joints to both ends of all control rods (Sonex plans show ball joint on one end only).
Of particular interest is how to hold the bell crank, without moving, at the desired 25 degree position. If I can achieve this, most of the other dimensions/requirements should not be so hard to achieve.
Re: Aileron control rod/bell crank rigging
Posted: Fri Mar 25, 2022 8:25 am
by Bryan Cotton
If they made one rod end left hand threads, then it’s easy to adjust. You twist the rod to lengthen or shorten.
Re: Aileron control rod/bell crank rigging
Posted: Fri Mar 25, 2022 6:14 pm
by Skippydiesel
Bryan Cotton wrote:If they made one rod end left hand threads, then it’s easy to adjust. You twist the rod to lengthen or shorten.
“IF” only Bryan. Twisting the rod results in equal screw in/out. I have to remove one end to make adjustments (I wish the first builder had followed the Sonex plan).
Still got to find a way of measuring/clamping the bell crank to 25 degrees. Might have to make up a 25 degree spacer - but how to “fix” bell crank while making the adjustments???
While on the subject of clamping - as an interim measure (before fine tuning, I assume that clamping the aileron to the flap, will deliver neutral aileron position - is this correct?
Re: Aileron control rod/bell crank rigging
Posted: Sat Mar 26, 2022 2:41 am
by Skippydiesel
FYI - Set your outer (short) control rod length to 480mm center to center.
Connect the rod to the aileron
Clamp your aileron to your flap - use a strait edge to check your trailing edges are level (this assumes the resulting position is aileron neutral, as per Sonex instructions).
Connect to bell crank.
Measure angle (see Sonex plans for detail) as best you can - should be fairly close to 25 degrees. Any adjustment will be small.
Remove clamp.
If all OK, tighten lock nut (s) while securely holding ball end in correct alignment.
(Clamp - I made mine from two large “fender” washers, wrapped in electricians insulating tape. Long narrow bolt, I used a 4mm, passed through both washers secured with wing nut. Take care not to screw i too tight, just enough to hold both flap & aileron in alignment)
Re: Aileron control rod/bell crank rigging
Posted: Sat Mar 26, 2022 8:21 am
by DCASonex
Bryan Cotton wrote:If they made one rod end left hand threads, then it’s easy to adjust. You twist the rod to lengthen or shorten.
If anyone does build it with right and left hand threads, like an extra long turnbuckle, be sure to safety wire those ends. That “easy” adjustment is not something you want happening in flight.
David A
Re: Aileron control rod/bell crank rigging
Posted: Sat Mar 26, 2022 8:39 am
by Bryan Cotton
DCASonex wrote:
Bryan Cotton wrote:If they made one rod end left hand threads, then it’s easy to adjust. You twist the rod to lengthen or shorten.
If anyone does build it with right and left hand threads, like an extra long turnbuckle, be sure to safety wire those ends. That “easy” adjustment is not something you want happening in flight.
David A
Very true. Sikorsky helicopters use this extensively and they are safetied.
Still important to safety when only one end adjusts.
The OPs issue still seems easy. Fix one end, adjust the other. When adjusted, if you don’t like one end, turn both sides the same number of turns until you are happy.
Re: Aileron control rod/bell crank rigging
Posted: Sat Mar 26, 2022 5:35 pm
by Skippydiesel
DCASonex wrote:
Bryan Cotton wrote:If they made one rod end left hand threads, then it’s easy to adjust. You twist the rod to lengthen or shorten.
If anyone does build it with right and left hand threads, like an extra long turnbuckle, be sure to safety wire those ends. That “easy” adjustment is not something you want happening in flight.
David A
This is not a turnbuckle.
Please excuse my ignorance but how do you safety wire a ball end joint ??
Re: Aileron control rod/bell crank rigging
Posted: Sat Mar 26, 2022 11:41 pm
by peter anson
It is possible to get nuts that have a lock wire hole and I have seen rod ends that are drilled for lock wiring but it’s a sure bet that your aircraft doesn’t have that type. All my control rods are fitted with right hand rod ends at both ends and just locked with a lock nut. It’s possible to check many of them when doing the daily pre-flight and for anything to shift, two lock nuts must come loose. I don’t recall it being difficult to rig. Clamp the aileron in place; set the bell crank at the correct angle and adjust the control rod ends until the holes line up.
Peter
Re: Aileron control rod/bell crank rigging
Posted: Sun Mar 27, 2022 3:50 am
by Skippydiesel
peter anson wrote:It is possible to get nuts that have a lock wire hole and I have seen rod ends that are drilled for lock wiring but it’s a sure bet that your aircraft doesn’t have that type. All my control rods are fitted with right hand rod ends at both ends and just locked with a lock nut. It’s possible to check many of them when doing the daily pre-flight and for anything to shift, two lock nuts must come loose. I don’t recall it being difficult to rig. Clamp the aileron in place; set the bell crank at the correct angle and adjust the control rod ends until the holes line up.
Peter
The rod (ball joints) ends have a “witness” hole drilled through - this is to make sure your threaded (male) end goes in at least as far as the witness hole. I suppose I could drill another two holes and purchase lock nuts with a hole in but Sonex dont call for it and I am inclined to go with your approach.
On my Sonex its impossible to tighten the lock nuts in situ - the rod must be adjusted as best I can, very carefully removed, placed in a padded vice, first lock nut tightened, second carefully tightened, so ball end at 90 degrees to the first.- replaced and bell crank angle checked. I did this at least 6 times to get the angles correct. As mentioned above I measured the first assembly and used that measurement to do the second set up in just about 3 repeats.
The difficulty is getting the 25 degrees -Its hard to measure in such a confined space and once measured, easy to knock out of position. I have done it now but to double check will get my Son to make up a 25 degree spacer in his 3D printer.
Not having flown a Sonex I suspect that the bell crank angle is key to effective aileron differential movement and when turning (using just aileron), minimal/nil initial yaw.
Re: Aileron control rod/bell crank rigging
Posted: Sun Mar 27, 2022 6:13 am
by peter anson
You don’t necessarily need to tighten the lock nuts with the control rod in situ. I would suggest adjusting it to the correct length and then removing the rod to tighten the interior lock nut. If you need to make any further minor adjustments you can do it on the external rod end. As far as preventing the bell crank from moving from its 25° position, it should be possible to clamp the far end of the long push rod against the spar using a G clamp and some suitable padding.
Peter
Re: Aileron control rod/bell crank rigging
Posted: Sun Mar 27, 2022 6:23 pm
by Skippydiesel
peter anson wrote:You don’t necessarily need to tighten the lock nuts with the control rod in situ. I would suggest adjusting it to the correct length and then removing the rod to tighten the interior lock nut. If you need to make any further minor adjustments you can do it on the external rod end. As far as preventing the bell crank from moving from its 25° position, it should be possible to clamp the far end of the long push rod against the spar using a G clamp and some suitable padding.
Peter
Hi Peter - Tightening lock nuts - that’s exactly what I did.
Future adjustment in situ - if not impossible, very close to it. The adjustment of the short rod can only be done once the locks are loose. Loosening in situ may just be possible on the leading ball joint lock nut BUT the whole shebang must be removed for final tightening.
Yes your clamping of the long control rod could work - probably best with the help of an assistant. If I have to do further “tweaking” will give your suggestion a go. Thanks.
Re: Aileron control rod/bell crank rigging
Posted: Mon Mar 28, 2022 9:15 pm
by Skippydiesel
Son made up the 25 degree thin wedge for me.
Previous effort very close but needed some minor adjustment to be “spot on”. All done now!
Re: Aileron control rod/bell crank rigging
Posted: Tue Mar 29, 2022 10:33 pm
by Tony4aro
Skippydiesel wrote:[q…
The difficulty is getting the 25 degrees -Its hard to measure in such a confined space and once measured, easy to knock out of position. I have done it now but to double check will get my Son to make up a 25 degree spacer in his 3D printer.…
If you can share the model… I would love to have it. I’m just getting read to do this to my Waiex. (I can print my own spacer) Thanks
Re: Aileron control rod/bell crank rigging
Posted: Wed Mar 30, 2022 7:05 am
by Skippydiesel
peter anson wrote:You don’t necessarily need to tighten the lock nuts with the control rod in situ. I would suggest adjusting it to the correct length and then removing the rod to tighten the interior lock nut. If you need to make any further minor adjustments you can do it on the external rod end. As far as preventing the bell crank from moving from its 25° position, it should be possible to clamp the far end of the long push rod against the spar using a G clamp and some suitable padding.
Peter
Yep! that’s pretty much what I have done, except:
On my Sonex its not possible to adjust the rod in situ & lock it. You can adjust in situ, with one or both lock nuts loose but the rod must be removed to tighten one/both lock nuts.
I have come to the conclusion that the 25 degree adjustment can not be done accurately, without the aid of a 25 degree spacer (my Son made mine using a CAD system and laser printer, he just happens to own).
Clamping the long push rod is not necessary, if you have a 25 degree spacer (I am surprised Sonex dont offer such a simple device).