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  #21  
Old 09-09-2017, 07:53 PM
BillSchlatterer BillSchlatterer is offline
 
Join Date: Jan 2005
Location: Arkansas
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Default Probably too simple but .....

Might not be your problem but I know about this because it happened to me! Full confession, from 20 feet away, it looked perfectly straight and the aileron to inside tip fit was perfect. I never stretched a line until after I had final drilled the tip. Fortunately, we noticed it before it was too late.



After finding the issue, we also found we could not just shift the tip and redrill so we had to split the tip across the back and then reglass it. Pretty easy fix actually, maybe an hour to do and then let it set.

Now having seen that, I look for it in other airplanes and you would be surprised to see how many are really not straight although the inside part of the tip is perfectly aligned. It's easy for the outside tip edge to be low. Can't quantify the impact but it can't be good.

They always told me to fix glass first and then bend metal. Just saying it is something that can be easily overlooked because it is almost too obvious. I didn't notice anyone suggesting that you check it but I thought I would throw it out there just to be sure.

Bill
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Last edited by BillSchlatterer : 09-09-2017 at 07:56 PM.
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  #22  
Old 09-10-2017, 05:44 AM
Capt Capt is offline
 
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Quote:
Originally Posted by BillSchlatterer View Post
Might not be your problem but I know about this because it happened to me! Full confession, from 20 feet away, it looked perfectly straight and the aileron to inside tip fit was perfect. I never stretched a line until after I had final drilled the tip. Fortunately, we noticed it before it was too late.



After finding the issue, we also found we could not just shift the tip and redrill so we had to split the tip across the back and then reglass it. Pretty easy fix actually, maybe an hour to do and then let it set.

Now having seen that, I look for it in other airplanes and you would be surprised to see how many are really not straight although the inside part of the tip is perfectly aligned. It's easy for the outside tip edge to be low. Can't quantify the impact but it can't be good.

They always told me to fix glass first and then bend metal. Just saying it is something that can be easily overlooked because it is almost too obvious. I didn't notice anyone suggesting that you check it but I thought I would throw it out there just to be sure.

Bill
That's a good photo of a misaligned tip. I did mention tip placement in an early post.
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  #23  
Old 09-10-2017, 07:35 PM
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flyenforfun flyenforfun is offline
 
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Thanks Scott for your information I had advice . All of the rigging and incidents checks and so forth and so on for Done during the building process five years ago and it was done as per Van's instructions. I don't remember all the specific details but at the time everything checked out. I have been playing with different hinge configurations i.e. raising and lowering the hinge of both Ailerons I also have tried trim tabs on the Ailerons and rudder and we have gotten different results but I can tell so far we have not found the culprit . The airplane always slowly rolls to the left as the speed increases requiring right trim and slowing down the airplane it starts rolling to the right requiring less right trim. The ailerons can be held neutral and the plane will fly true throughout the speed range however you can't let go of the stick and less you trim the airplane. In other words some force is deflecting one of those ailerons either up or down. I'm wondering if it has something to do with the counterweights I never weighed them when I installed them so I do not know if one is heavier than the other and if it was would it make a difference .
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  #24  
Old 09-10-2017, 07:41 PM
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flyenforfun flyenforfun is offline
 
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The ball is a little to the right and cruise flight I put a trim tab on the righside of the rudder and it centered the ball but I still have the roll problem
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  #25  
Old 09-11-2017, 04:07 AM
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flyenforfun flyenforfun is offline
 
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Quote:
Originally Posted by BillSchlatterer View Post
Might not be your problem but I know about this because it happened to me! Full confession, from 20 feet away, it looked perfectly straight and the aileron to inside tip fit was perfect. I never stretched a line until after I had final drilled the tip. Fortunately, we noticed it before it was too late.



After finding the issue, we also found we could not just shift the tip and redrill so we had to split the tip across the back and then reglass it. Pretty easy fix actually, maybe an hour to do and then let it set.

Now having seen that, I look for it in other airplanes and you would be surprised to see how many are really not straight although the inside part of the tip is perfectly aligned. It's easy for the outside tip edge to be low. Can't quantify the impact but it can't be good.

They always told me to fix glass first and then bend metal. Just saying it is something that can be easily overlooked because it is almost too obvious. I didn't notice anyone suggesting that you check it but I thought I would throw it out there just to be sure.

Bill
Thanks Bill but I think we check that five years ago but I will look at it again thanks for the information
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  #26  
Old 09-11-2017, 04:15 AM
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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.
That's interesting maybe the straw is acting like A trim tab . What aileron did you put it on again? The light one?
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  #27  
Old 09-11-2017, 04:19 AM
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Quote:
Originally Posted by rvbuilder2002 View Post
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).
Thanks Scott for your information I had advice . All of the rigging and incidents checks and so forth and so on for Done during the building process five years ago and it was done as per Van's instructions. I don't remember all the specific details but at the time everything checked out. I have been playing with different hinge configurations i.e. raising and lowering the hinge of both Ailerons I also have tried trim tabs on the Ailerons and rudder and we have gotten different results but I can tell so far we have not found the culprit . The airplane always slowly rolls to the left as the speed increases requiring right trim and slowing down the airplane it starts rolling to the right requiring less right trim. The ailerons can be held neutral and the plane will fly true throughout the speed range however you can't let go of the stick and less you trim the airplane. In other words some force is deflecting one of those ailerons either up or down. I'm wondering if it has something to do with the counterweights I never weighed them when I installed them so I do not know if one is heavier than the other and if it was would it make a difference .
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Matt Giordano Sr. and Jr.
RV-8 - N861MM
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  #28  
Old 09-11-2017, 04:35 AM
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flyenforfun flyenforfun is offline
 
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Here is an idea that I just had. The Pitot tube is a dynon avionics Pitot tube it is much larger than the one you build from Van's drawings also it is mount it further outboard then the stock tube. Is it possible that it's causing parasites drag or disrupting the airflow under the left aileron?? Any thoughts on that?
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  #29  
Old 09-11-2017, 12:56 PM
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David-aviator David-aviator is offline
 
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Matt, have tried very gentle squeeze of right aileron?
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  #30  
Old 09-11-2017, 01:05 PM
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flyenforfun flyenforfun is offline
 
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Quote:
Originally Posted by David-aviator View Post
Matt, have tried very gentle squeeze of right aileron?
Yes. I've tried everything checked everything tested everything your has to be something I'm missing. From the looks of this forum no one has found the smoking gun to this phenomenon just Band-Aids and patches.
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