gblwy

gblwy

Well Known Member
Hi,

My inspector in the UK just inspected my plane. He measured the maximum up and down angles of the flaperons and saw a 7 degree difference from one side to the other. This is consistent whether flaps are deployed or not.

I was pretty careful to ensure the torque tubes were the same, correct, length so I cannot explain the difference.

Has anyone measured these angles?

If not, does anyone have a view on whether this could be correct/acceptable? Otherwise, it's out with the trim and lift the floorboards again to investigate.


Thanks...Keith
 
Hey Keith

1. Are both sticks vertical when centered ?
2. If they are vertical, do both flaps set in the SAME position, regarless of angles ?

John Bender
 
Not symmetrical

Thanks for the quick reply, John.

When the flaperons are centralised (bearing in mind one droops 1/4", as per the PAP), one stick is maybe two inches closer to the longeron than the other. Doesn't souund right to me. Centring the stick will result in a roll, I'd think.

Cheers...Keith
 
Keith,

I had the same issue last week... the left side dropped less than the right by a few deg. I was not sure why but I ended up threading in the right flaperon pushrod bearing where it connects to the torque tube. Then I adjusted the right stick to center it up.

-Ron
 
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Page 31-09

Keith,
Did you use the AN3-21A bolt to line up the parts as shown on page 32-09 figure 2? And were the flapperons clamped in place as shown on the next page before drilling the WD-1214 torque tubes? If yes to both, and the control sticks are not centered, then the solution could be to adjust the length of the control stick push-rods F-1264 on page 32-05. I am sure that someone will correct me if there is a better way. I do not think that it matters if the control sticks are perfectly straight.
Joe
 
Hey Keith

At a quick glance, I'd say you needed to adjust BOTH pull rods at the same time to get the 1/4" droop on one side per the instructions. If you did it all on one side, it will not be correct. The 1/4" is a way of measuring how much you are adjusting. They still need to be equal. It was just a means to adjust the correct amount. 1/8" is needed for BOTH.

John Bender
 
From memory, I did exactly as per the plans. So far, I have not "adjusted" anything, just installed the torque tubes at the lengths specified in the plans. The 1/4" difference from left to right side is just there - nothing I have specifically done. Of course, I could have made a mistake with measuring the torque tubes, but I'm pretty sure I measured them against each other, so they should be the same length. Seems I'm going to have to open stuff up to take a look.

Cheers...Keith
 
Keith

If you installed a bolt or pin in the controls as called for ( locked them in place ), and you adjusted the sticks so they were vertical, then you were to have 'locked' the flaps in place ( by being sure they were flush with the wing ends ), THEN drilled the torque tubes per the instructions. After that, you were to adjust the pull tubes to make the 1/4" droop in the one by adjusting BOTH pull tubes equally. Sounds like you need to go back over the whole set of instructions for that section. Sorry !

John Bender
 
Thanks

Thanks everyone. I'll go and recheck everything. I'd like Vans to publish the angles so that the rigging can be checked easily.

Cheers...Keith
 
Ain't gonna happen!

gblwy said:
Thanks everyone. I'll go and recheck everything. I'd like Vans to publish the angles so that the rigging can be checked easily.
Cheers...Keith
Click to expand...

Wouldn't we all? It would make my job so much easier!
 
Observations

Hi Guys,

Today I removed the seat floor to see what is going on. As noted elsewhere, the bulkhead is now distorted where the stabilitor cables are tensioned. I suppose I'll have to slacken off the turnbuckles to reinstall the floor. Ugh, I hate that turnbuckle job.

When you install a bolt to lock the controls in the central position I see that the Y-shaped bellcrank is not aligned exactly fore and aft. Looking from the top it is rotated slightly anticlockwise. This should automatically introduce a slight droop in the left flaperon and raise the right one, other things being equal. I couldn't find a step in the plans to introduce the 1/8" down/up, so maybe this is how it happens automagically. Certainly the bias is in the appropriate direction.

The offset also means that if you prepare the two control stick torque tubes with equal lengths, the right stick is not vertical. Seems there should be a step in the plans to check this. I have now adjusted mine by lengthening the right tube.

None of this explains my significantly non-symmetrical flaperons. I have adjusted the lengths of the two long torque tubes. I have still got the required 1/4" variation from left to right as called out in the PAP, but this time with the controls locked in the central position (which was not specified in the PAP, or the plans as far as I can see). I also get maximum up/down deflections on the flaperons within 1 degree of each other in the flaps-raised position. As it happens not much adjustment was required to eliminate the asymmetry I measured. Maybe three turns of the rod-end bearings.

All of this feels better, but in the absence of any max deflection angles from Vans I don't know if it correct or not.

I also haven't removed the tank and the baggage bay inspection covers to look at the rear end of the torque tubes. Is it safe to assume that a slight shortening of one tube will not risk an over-centre situation which might lock the controls?

Thanks for your perseverance. I think I have learned more in the two months of debugging, than in the year of building. It's relatively easy slavishly following the plans with no comprehension of what's really happening.

FWIW, I have remeasured the angles.

With flaps up, I am now seeing a maximum up deflection of 22 degrees (port) and 23 degrees (starboard). Max down deflection is 11 degrees (port) and 12 degrees (starboard).

Full flaps lowers the port flaperon by 20 degrees, and the starboard flaperon by 18 degrees with the sticks centralised.

Full up deflection with full flaps results in 0 degrees (port), 2 degrees down (starboard). Full down deflection is 30 degrees (port) and 28 degrees (starboard).

Cheers...Keith
 
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Hey Keith

Can you take a picture of the control from DIRECTLY over top of it ? I want to see what you mean by not being centered.

John Bender
 
Under seat cover

Keith,
Instead of loosing the stabilator turnbuckles to get the under-seat cover back on, try putting the most forward screws in first to draw the bulkhead and cover together. If the screws are too short, then use hardware-store screws temporarily. After all of the other screws are in, replace the hardware-store screws one at a time with the AN screws.
Joe
 
Rethink

John,

I took a couple of photos. I'll try to post them tomorrow. Not easy, as the flap handle gets in the way.

Joe,

Thanks, I'll try your method of reattaching the seat floor.

I have just reconsidered what I wrote and did. On reflection, I think I have still not got it right. If the PAP says the right flaperon should droop by 1/4" when the left flaperon is held level, then I assume the goal is to have both flaperons droop by 1/8" in the centralised position. This is not what I said or did, so I will have to revisit.

It would be so much easier if Vans wouold just declare what the deflection limits should be.

Cheers...Keith
 
Picture of bellcrank offset

2iabvc8.jpg



As promised, here's the pic.

Cheers...Keith
 
Hey Keith

From the picture, it looks like things are centered. If you follow the instructions, put the pin in and lock the bellcrank in place, then the flaps should be equal. Also the sticks should be vertical. Adjusting for the 1/4" droop is after you have done everything else per the instructions. After that, you should have approximately 1/8" droop on BOTH, but equal.

John Bender
 
Not symmetrical

If you look at the front of the bellcrank you will see it is visible to the left of the flap handle but not the right. This makes the sticks asymmetrical unless you adjust the length of their torque tubes.

If you look at the back end of the inverted Y shape the left arm is maybe 1/16 inch further aft than the right arm.

Maybe the stick position isn't something you notice in flight. You only use one of them at a time ;-)

Interestingly as you deploy the first stage of flaps the tops of the two sticks move significantly closer together, maybe 2 inches, then move apart again as the second stage is deployed. With flaps retracted, my left stick is 0.5 inches closer to the nearest siderail than the right one. Having spent 5 hours (really) trying to put the washers and nut on the right stick after adjusting the length of the torque tube, I don't have the enthusiasm to fix the left one. I just want to join the ranks of the flying now!

Cheers...Keith



Cheers...Keith
 
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Hey Keith

Did you have the bolt/pin in place ( lock it ) when you took the picture ?

John Bender
 
See it now - sorry

Been a long time since I did that. With the flap handle in flaps-up position, your sticks should be vertical when the HS is in normal positon I'd say. Your flaps should be equal on both sides. About 1/8" droop each after final adjustment. If you adjust to that, everything should work well.

John Bender
 
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