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  #11  
Old 09-08-2017, 01:20 PM
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bruceh bruceh is offline
 
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Gear leg fairings?
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  #12  
Old 09-08-2017, 03:04 PM
N999BT N999BT is offline
 
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Default Gear Leg Fairings

I thought of that, but since they don't move at all I figured it couldn't be them. When fast it rolls right, slow it rolls left. I think it has to be airflow around the ailerons...
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  #13  
Old 09-08-2017, 03:49 PM
PilotjohnS PilotjohnS is offline
 
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Default huh?

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Originally Posted by N999BT View Post
I thought of that, but since they don't move at all I figured it couldn't be them. When fast it rolls right, slow it rolls left. I think it has to be airflow around the ailerons...
This suggested to me the current fix may not be the correct one. Maybe an issue was compensated for and not corrected, hence the "fix" only balances out that tendency at one airspeed? JMHO
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  #14  
Old 09-08-2017, 06:04 PM
Berchmans Berchmans is offline
 
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Default Elevators?

Are the elevators in alignment? I once had a yaw problem on my float plane ( I know not related) turned out that when retracted the water rudders were out of alignment. Elevators could cause a roll tendency of properly aligned.
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  #15  
Old 09-08-2017, 06:13 PM
jklusman jklusman is offline
 
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Location: Lafayette, IN
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My RV-8 had a heavy left wing when I bought it in 2013. I followed a suggestion I think I read on this forum, and it immediately fixed the problem. The suggestion was: Cut a small coffee-stirring straw in half and tape it to the bottom aft end of the opposite aileron, parallel to and about 1/4 inch forward of the trailing edge. Use clear packing tape to secure the straw. I secured the straw roughly in the middle of the aft aileron span. The straw and tape have remained in place for 4.5 years. This sounds too easy to be true, but I'm not joking -- it did the job.
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  #16  
Old 09-08-2017, 11:48 PM
rv8ch rv8ch is offline
 
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Default good tip

Quote:
Originally Posted by jklusman View Post
My RV-8 had a heavy left wing when I bought it in 2013. I followed a suggestion I think I read on this forum, and it immediately fixed the problem. The suggestion was: Cut a small coffee-stirring straw in half and tape it to the bottom aft end of the opposite aileron, parallel to and about 1/4 inch forward of the trailing edge. Use clear packing tape to secure the straw. I secured the straw roughly in the middle of the aft aileron span. The straw and tape have remained in place for 4.5 years. This sounds too easy to be true, but I'm not joking -- it did the job.
Gonna file this one away for the future. Another example showing aerodynamics is complex.
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  #17  
Old 09-09-2017, 06:53 AM
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agirard7a agirard7a is offline
 
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Location: Newport, RI
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Default Elevators

When I was aligning my elevators, I used an 8' alum. straight edge on the trailing edge. I discovered that elevator horns (where the counter weights are mounted) did not align with the horizontal stabilizer. If one side was flush, the other was off by 3/16". I had a choice, either a straight trailing edge or misalignment with the counter balance arms meeting the HS. Vans, told me this was a common problem. I chose the straight trailing edge. A friend did the opposite aligning the horns, he now has a heavy wing. Just a thought, check out your elevator trailing edges with a straight edge.
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Last edited by agirard7a : 09-09-2017 at 07:02 AM.
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  #18  
Old 09-09-2017, 07:06 AM
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David-aviator David-aviator is offline
 
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FWIW - Solved heavy left wing by slightly squeezing right wing aileron bend full length.

Then had heavy right wing!!

Squeezed left wing aileron slightly at one panel between ribs, airplane now flies wings level by itself.
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  #19  
Old 09-09-2017, 01:09 PM
Aluminum Aluminum is offline
 
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Location: San Jose, CA
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Quote:
Originally Posted by jklusman View Post
My RV-8 had a heavy left wing when I bought it in 2013. I followed a suggestion I think I read on this forum, and it immediately fixed the problem. The suggestion was: Cut a small coffee-stirring straw in half and tape it to the bottom aft end of the opposite aileron, parallel to and about 1/4 inch forward of the trailing edge. Use clear packing tape to secure the straw. I secured the straw roughly in the middle of the aft aileron span. The straw and tape have remained in place for 4.5 years. This sounds too easy to be true, but I'm not joking -- it did the job.
In other words, a Gurney flap?

https://en.wikipedia.org/wiki/Gurney_flap
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  #20  
Old 09-09-2017, 05:59 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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The of the different advice and ideas is great, but a lot of it misses the mark.

If there is a problem related to the ailerons (likely since the OP said if he manually holds the ailerons in neutral, the airplane fly's straight), then using a lot of different methods to counter the roll, but totally bypassing fixing the actual problem is not the sensible way to fix it.

BTW, split alignment on elevators has very little (if any) noticeable influence on roll trim. You need to think about the leverage available... The elevators are very short in span compared to the wings. Any roll they can induce has a very small moment. That is why adjusting the flaps has only a very small effect on roll trim.
The ailerons though have a large moment way out at the end of the wing. That is why a very small aileron abnormality have a large influence on roll trim.

Just squeezing the trailing edge is not totally the correct way to solve a roll trim problem. You could do that and get the trim adjusted, but still have two ailerons that are equally not the correct shape.

As I mentioned previously, the very first thing that should be checked is that the ailerons themselves are actually built to the correctly (primarily trailing edge shape).
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Last edited by rvbuilder2002 : 09-09-2017 at 06:02 PM.
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