Aileron Deflection Adjustment

[Skippydiesel]

As per the instructions I;

Securely locked my control columns in the vertical position.
Adjusted the bell-cranks to 25 degrees using the long rods
Adjusted the aileron to 74mm (over the spar) by adjusting short rod

The plans call for 20.5 degrees Up and 11.5 degrees Down Aileron Deflection

Using a digital level , zeroed on the trailing edge of each wing, just ahead of the aileron, I measured

Left Aileron - Up 15.3 degrees - Down 11.5 degrees
Right Aileron - Up 18.5 degrees - Down 9.5 degrees

Clearly further adjustment is required.

I assume I must change the 25 degree bell-crank angle, using the long rods and then readjust the aileron using the short rods.

Do I lengthen or shorten the long rods ie decrease /increase from the 25 degree bell-crank preset?

I hope to do the adjustment within the next 2-3 days - Please advise.

[sonex1566]

Hi Sean,
I had a similar problem with my Sonex that I scratch built. I think my problems were caused by either my trailing edge spar being a bit out of wack or the aileron skins not been folded acurately enough. I went to a lot of trouble to fit my hinges in the right spot as per the plans, but the distance was a little out between the hinge line and the push rod. This meant that the aileron throw was not correct. You have to maintain the 25 degree angle of the bell crank otherwise your aileron differential will be wrong. If you remove the bolt from the push rod and just hold it with your fingers while you operate the ailerons you can see the difference it makes when you move the push rod up, down etc in terms of how much movement you get. If you can do this with the flaps fitted you are a frigging legend, however I am a knuckle dragging rock ape and had to take the flap off to manage this. I ended up remaking the end plates on the ailerons. I simply traced around the old ones to keep the rivet holes in the right spot and left more metal around the bolt hole to enable me to make adjustments. I cut the excess metal off after drilling the mounting hole. It sounds far worse than what it actually is to do. The only shitty part is obtaining the 3/16" plate ( if I remember correctly ) in Australia. I bought my materials from Airport Metals in Melbourne at the time. I can't remember if they will sell you just a square foot or whether they cut a slice off a full sheet. You'll need to ask nicely! Good luck.

[Skippydiesel]

Hi Richard,

Thank you for your advice - sorry to hear about the need to backtrack on aspects of your build.

My aircraft is now flying - the adjustments to flight surfaces is what I would describe as fine tuning/tweaking to get a nice handling efficient airframe.

I understand that changing the 25 degree bell-crank angle will change the differential movement of the ailerons, however it seems to me that a small change in the angle may benefit the symmetrical movement of the ailerons ie both sides moving through the same range of movement ( I don't quite have that at the moment). I would expect/hope that this would result in a more balanced aircraft.

I am the second builder of my Sonex. The first, a builder of extraordinary attention to detail, did most of the airframe fabrication and I would bet, has located the bell-cranks in precisely the correct position/dimensions, according to the plans - it is he who is encouraging a change to the bell-crank angle to achieve greater conformity in aileron movement.

What I need now is advice from someone who has been down this track and knows what the end result may be.

[Skippydiesel]

Anyone at all been down this track???

[Skippydiesel]

Anyone out there able to advise on aileron rigging??

[sonex1566]

Hi Sean,
As you gathered from my previous post I had to modify my aileron horns to decrease the distance from the push rod hole to the hinge line to increase my control throw as shown on the plans. I reckon that I was out by maybe 1/8" is. It sounds like it wouldn't make much difference but if you watch the movement of the bell crank it's easy to see how a bit of error can creep up on you. My control movements and elevator 'droop' are as per the plans. So in the cruise my trim tab is pretty well bang in the middle. When I roll to the right the ball pretty well stays in the middle whilst a roll to the left needs a dash of left rudder to keep it centred, and I really do mean only a little bit. My old Jabiru SK required your feet to always move with the stick and quite a bit at times to counter the adverse yaw. It would make an interesting experiment in my case to adjust the thrust line a touch so that you didn't need any rudder trim in cruising flight and then see if it rolled in both directions without needing any rudder input.

However much I really do enjoy experimental aviation there is a limit to what I am personally willing to stick my neck out! I thoroughly enjoy flying my little plane, it's a blast. I personally think that it's more prudent to set up the movements and throws as per the plans first before reinventing the wheel. They don't call me Captain Chicken shit for nothing you know!

[Skippydiesel]

Hi Richard,

When (in the build process) did you discover your fabrication error? I ask because changing the bell crank location now that the wing has been closed (all solid rivets) is a to say the least a daunting task.

As you can see by my digital level measurements, my ailerons movement/deflections are not so far out, when compared with each other. They are some way from the plans specification. From my perspective the ailerons moving through the same deflection range is more important than achieving the plans range. My theory being that symmetrical & predictable movement will be sufficient to have a well behaved aircraft.

I found it extremity difficult to get an accurate 25 degree's on one of the bell-cranks - its the one where the corresponding rib hole has the flair facing the crank. It could just be that this bell-crank needs further attention. To do this, a change in the long aileron rod length may have to be made.

[sonex1566]

Hi Sean,
I've drawn a picture to try and explain myself. Please be aware that this is from memory as my plans are out at my hangar, but hopefully you will get the general idea. Yes the thought of getting into the wing to fix the bell crank is horrible, I've got big hands and it sucks. So providing that you can get full left and right stick movement AND the bell cranks are at the 25 degree angle in the neutral position then the bell cranks are OK. The next silly question is...if the push rods are removed from the aileron, can you get the full range of movement then? Again, as I've got big hands, I need to disconnect the push rod from the flaps so that they can hang down out of the way to do this. So assuming that the ailerons can move the entire range as per the plans, the bell crank is moving it's entire movement as per the plans which is controlled by the stops on the control column, then the only thing left is the distance 'A' as shown on my little picture. This is the mistake that I made. I can't remember if the distance is specified on the plans, I simply rivetted the aileron control horn into the middle of the end rib of the aileron and assumed everything was OK. I remember going to great lengths to set the location of the hinge line in relation to the aileron, but I'm stuffed if I can remember setting the distance 'A' shown on my drawing. My solution to remake the control horn for the ailerons is quite simple to fix, by using the old ones as a guide, I didn't stuff up any rivet holes in the aileron and the whole thing was fixed in a couple of hours. Even my swear jar didn't cop a hammering!

Sonex aileron schematic.pdf

Schematic of aileron control on Sonex wings.

(305.3 KiB) Downloaded 111 times

I'm planning on flying into the Avalon Airshow in March. If you make it there, come over for a chat. We can discuss Sonex's till the cows come home.

[Area 51%]

If the dimensions for the pushrod attach hole in relation to the aileron is on the print, I can't find it. The drive plate is shown as an Aircraft Kit Component and the holes are already located on the part. The only dimensions I can see are the relationship of the drive plate to the aileron. The flap drive plate has the hole location listed.

The location vertically of the hole would have a significant impact on the amount of travel of the aileron. To the best of my measuring skills, it looks like just under 7/8in up from the bottom of the aileron is where the hole should be.

[Skippydiesel]

Sonex1566/Richard,

Thank you for your draftsmanship/picture and all your very good advice however I feel I should revisit my 25 degree settings first.

As I said, the difficult to set one, may be out by just enough, to be causing my asymmetrical aileron deflection - will get to this over the next few days weather permitting (the poor girl is in the open).

As for Avalon. Thanks for the offer - may get there one day - I will be lucky to have flown all the RAAs test chores by then but expect the 25 hrs to be well past. Also still grappling with less than perfect engine (oil/coolant)temperatures, which may require a cooling system layout and cowling air flow management rethink.