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Mauledriver(at)nc.rr.com
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 Posted: Wed Feb 13, 2013 11:44 am Post subject: Measuring Aileron Height - was Pesky heavy left wing |
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I've been trying to fix a heavy left wing as well. After doing a number of things and having some success, I'm going back to the beginning with the wings. I've lined up the flaps so that 1) they are even with the bottom of the fuse and 2) They have the same angular relationship to the the wing skins in the reflex position (used a digital level).
I'm now looking at the aileron height and believe that my left aileron may be a slightly higher than my right but I can't figure out how to confirm that. Carl said, "check the aileron height (compare left/right at inboard and outboard attach points using a straight edge running aft off the wing)" but I can't quite figure out how to do that. Where does the straight edge lie and what are you measuring alignment with?
Any insight here is appreciated.
Thanks all for posting your work here. And I did go to the RV8 list looking for same.
Bill "thinking he probably should just re-attach the trim servo and leave it all alone" Watson
On 1/26/2013 6:48 PM, Carl Froehlich wrote:
[quote] <![endif]--> <![endif]-->
Recommend first rigging the flaps to be exactly correct - both flush with the underside of the fuselage. From there start your other rigging checks. Hopefully this will get you on the right path. If you find you do have a twisted flap, then don’t rig the aileron tailing edge to be in line with the offending flap. Rig the ailerons using a straight edge such that they match. This will mitigate a twisted flap problem.
Below are a couple of earlier posts I made on rigging that you may find useful.
Carl
60 hours on the RV-10 and one long cross country. Here are some recent tweaks that I’ve incorporated:
- Added a .063” shim under the forward HS spar. This moved the elevators to a better trail position in cruise. I had a .040” shim in for 10 hours or so. It helped but was not quite enough. Even with this larger shim I have more nose up trim authority than I will ever need. With anything other than forward CG conditions however the elevators are still slightly trailing edge down. This calls for a larger shim but the .063” is about all I want to do for now as more may force an empennage fairing adjustment and/or re-hanging the rudder. For those wondering, my W&B is typical of other RV-10s.
- Right wing slightly heavy. Not so bad that aileron trim would not fix, but not right. After some careful measurements I found the right aileron inboard hinge placed the aileron slightly high (as compared to the outboard hinge and the left aileron). I lowered the inboard side of the aileron .032” or so and this resolved the wing heavy issue.
- Ball not centered. I chased my tail on this for some time. With the wheel pants and gear leg fairing off the ball is dead center. Various tweaks on the pants and fairings either had the ball ½ out left or right. After several tries it is now dead center (and just finished final pant and fairing paint today). Some take-aways for those working this issue:
o The fairing adjustments are far more critical than the wheel pants at affecting the ball. Set the wheel pants as close as possible, then make all adjustments to the fairings after that.
o The Van’s instructions lead you to think you can mount the wheel pants with the plane on the gear. I don’t recommend this.
o You can never be too accurate setting up to check the fairing rig. A 1/16” move of the fairings trailing edge equals ¼ ball or so.
- Don’t paint the pants or fairings until after you are flying.
- Add the “reinforcement glass” to the nose gear wheel pant (there was a recent thread on this). After mine cracked, I added two layers of carbon fiber to the inside, ground out the crack and filled it in with flox, sanded then two layers of regular glass on the outside over the crack. This was followed by the normal “micro-balloon and sand until you puke” routine.
As already mentioned, check the aileron height (compare left/right at inboard and outboard attach points using a straight edge running aft off the wing). A very small difference between aileron heights will make a big difference – and just how heavy the wing is will be dependent on speed. I found this problem in several heavy wing RVs, including my RV-8A. Moving the offending attachment point completely solve my problem on the 8A.
Other things to look at:
- Do not assume that if the ailerons (in neutral position) are even with the flaps (in reflex position) that they are rigged correctly as there may be a slight twist in the flap. Put the flaps in the reflex position, clamp one aileron to the flap, then compare using a straight edge running aft off the wing the two ailerons deflection. If there is a difference, adjust the push rods until they are exactly the same.
- Do the same straight edge measurement on the flaps to compare. If you do have a slight twist in a flap, I would expect that you can compensate for it if the ailerons are symmetrically rigged as they provide the higher moment arm.
- Once you have the ailerons at the same deflection, then look at the wingtips. When building the wingtips you can move the wingtip tailing edge up or down a good quarter of an inch when fitting the aft rib.
Of note, the easy tone in Van’s instructions on rigging the aircraft never seemed right for me. After chasing my tail on a heavy wing I went back to basics as discussed above and found the small difference in aileron mount height. Rigging is a big deal – and something that few will get right on the first attempt.
--
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rv10rob(at)gmail.com
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| Posted: Wed Feb 13, 2013 2:52 pm Post subject: Measuring Aileron Height - was Pesky heavy left wing |
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I know this has been brought up before, but don't you need to have the flaps all the way up against the spar in the reflex position to avoid stressing the flap actuation system in cruise?
On Wed, Feb 13, 2013 at 11:43 AM, Bill Watson <Mauledriver(at)nc.rr.com (Mauledriver(at)nc.rr.com)> wrote:
[quote] I've been trying to fix a heavy left wing as well. After doing a number of things and having some success, I'm going back to the beginning with the wings. I've lined up the flaps so that 1) they are even with the bottom of the fuse and 2) They have the same angular relationship to the the wing skins in the reflex position (used a digital level).
I'm now looking at the aileron height and believe that my left aileron may be a slightly higher than my right but I can't figure out how to confirm that. Carl said, "check the aileron height (compare left/right at inboard and outboard attach points using a straight edge running aft off the wing)" but I can't quite figure out how to do that. Where does the straight edge lie and what are you measuring alignment with?
Any insight here is appreciated.
Thanks all for posting your work here. And I did go to the RV8 list looking for same.
Bill "thinking he probably should just re-attach the trim servo and leave it all alone" Watson
On 1/26/2013 6:48 PM, Carl Froehlich wrote:
[quote]
Recommend first rigging the flaps to be exactly correct - both flush with the underside of the fuselage. From there start your other rigging checks. Hopefully this will get you on the right path. If you find you do have a twisted flap, then don’t rig the aileron tailing edge to be in line with the offending flap. Rig the ailerons using a straight edge such that they match. This will mitigate a twisted flap problem.
Below are a couple of earlier posts I made on rigging that you may find useful.
Carl
60 hours on the RV-10 and one long cross country. Here are some recent tweaks that I’ve incorporated:
- Added a .063” shim under the forward HS spar. This moved the elevators to a better trail position in cruise. I had a .040” shim in for 10 hours or so. It helped but was not quite enough. Even with this larger shim I have more nose up trim authority than I will ever need. With anything other than forward CG conditions however the elevators are still slightly trailing edge down. This calls for a larger shim but the .063” is about all I want to do for now as more may force an empennage fairing adjustment and/or re-hanging the rudder. For those wondering, my W&B is typical of other RV-10s.
- Right wing slightly heavy. Not so bad that aileron trim would not fix, but not right. After some careful measurements I found the right aileron inboard hinge placed the aileron slightly high (as compared to the outboard hinge and the left aileron). I lowered the inboard side of the aileron .032” or so and this resolved the wing heavy issue.
- Ball not centered. I chased my tail on this for some time. With the wheel pants and gear leg fairing off the ball is dead center. Various tweaks on the pants and fairings either had the ball ½ out left or right. After several tries it is now dead center (and just finished final pant and fairing paint today). Some take-aways for those working this issue:
o The fairing adjustments are far more critical than the wheel pants at affecting the ball. Set the wheel pants as close as possible, then make all adjustments to the fairings after that.
o The Van’s instructions lead you to think you can mount the wheel pants with the plane on the gear. I don’t recommend this.
o You can never be too accurate setting up to check the fairing rig. A 1/16” move of the fairings trailing edge equals ¼ ball or so.
- Don’t paint the pants or fairings until after you are flying.
- Add the “reinforcement glass” to the nose gear wheel pant (there was a recent thread on this). After mine cracked, I added two layers of carbon fiber to the inside, ground out the crack and filled it in with flox, sanded then two layers of regular glass on the outside over the crack. This was followed by the normal “micro-balloon and sand until you puke” routine.
As already mentioned, check the aileron height (compare left/right at inboard and outboard attach points using a straight edge running aft off the wing). A very small difference between aileron heights will make a big difference – and just how heavy the wing is will be dependent on speed. I found this problem in several heavy wing RVs, including my RV-8A. Moving the offending attachment point completely solve my problem on the 8A.
Other things to look at:
- Do not assume that if the ailerons (in neutral position) are even with the flaps (in reflex position) that they are rigged correctly as there may be a slight twist in the flap. Put the flaps in the reflex position, clamp one aileron to the flap, then compare using a straight edge running aft off the wing the two ailerons deflection. If there is a difference, adjust the push rods until they are exactly the same.
- Do the same straight edge measurement on the flaps to compare. If you do have a slight twist in a flap, I would expect that you can compensate for it if the ailerons are symmetrically rigged as they provide the higher moment arm.
- Once you have the ailerons at the same deflection, then look at the wingtips. When building the wingtips you can move the wingtip tailing edge up or down a good quarter of an inch when fitting the aft rib.
Of note, the easy tone in Van’s instructions on rigging the aircraft never seemed right for me. After chasing my tail on a heavy wing I went back to basics as discussed above and found the small difference in aileron mount height. Rigging is a big deal – and something that few will get right on the first attempt.
--
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http://www.matronics.com/Navigator?RV10-List |
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Bob Turner
Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA
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| Posted: Wed Feb 13, 2013 5:35 pm Post subject: Re: Measuring Aileron Height - was Pesky heavy left wing |
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1. Yes, the flaps should rest against the aft spar in the full up position.
2. With the aileron in neutral position, lay a 6" straight edge in a fore-aft direction, half on the wing and half on the aileron (do this both at the inboard and outboard aileron ends). The aileron should just barely touch the straight edge, when it's flat along the wing.
My experience was that this was a very sensitive measurement. I had an obviously heavy left wing (I didn't quantify it any more than that), and it was 80% fixed by lowering the outboard attachment by 1/32" or 1/16". I'm sure another 1/32" would fix it entirely. But it now is at the point where 15 minutes of fuel burn from the left tank fixes it, too, so it's not a high priority.
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http://www.matronics.com/Navigator?RV10-List |
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johngoodman
Joined: 18 Sep 2006
Posts: 530
Location: GA
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| Posted: Thu Feb 14, 2013 5:51 am Post subject: Re: Measuring Aileron Height - was Pesky heavy left wing |
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Just to muddy the water further, perhaps the wing tips is the problem - if the port one's trailing edge bends up a little, or the starboard one bends down, that would create a heavy left wing, as well.
John
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