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  #11  
Old 03-01-2014, 09:46 AM
terrye terrye is offline
 
Join Date: Feb 2010
Location: Vancouver, BC, Canada
Posts: 643
Default Tuft Testing

You could try tufting the underside of the outboard wing and aileron, and mounting a GoPro camera under the wing to record the tuft activity during aileron deflection. I suspect the aileron leading edge trips the boundary layer and causes turbulence on the underside of the aileron.
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RV-9A (Fuselage)
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  #12  
Old 03-01-2014, 10:32 AM
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Snowflake Snowflake is offline
 
Join Date: Oct 2009
Location: Victoria, BC, Canada
Posts: 2,953
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Ah, yes, at 140mph you should be good... I agree with others who suggest you may not be getting the same deflection on each side. The airflow over the aileron is separating and re-attaching in quick succession, which is what gives the buffet. The question is what's making it separate in the first place.

Slight differences in rigging from side to side could have your aileron higher or lower relative to the main body of the wing... That could subtly affect the point at which it trips.

Another thing to try is just bringing the stick back a few degrees towards center when you feel the buffet... You don't really need full aileron to do a nice roll.
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1996 RV-6 "Tweety" C-FRBP (formerly N196RV)
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  #13  
Old 03-01-2014, 11:01 AM
crabandy crabandy is offline
 
Join Date: Jan 2010
Location: Ottawa, Ks
Posts: 1,769
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I have noticed the same issue, buffeting with full right aileron but not with the left. I'm thinking the ailerons are positioned slightly different on the wing, which could also be causing my heavy left wing. I've followed Van's checklist for diagnosing and fixing a heavy wing as far as rigging is concerned and everything seems correct.
Possibly my right aileron is 1/32 lower causing a buffet and heavy left wing. I've installed a foam wedge (3 inches long 1/4 inch tall) under the right aileron to temporarily fix the heavy wing until I get all of the fairings installed.
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  #14  
Old 03-01-2014, 06:06 PM
petersb petersb is offline
 
Join Date: Mar 2008
Location: Toronto
Posts: 326
Default

Quote:
Originally Posted by crabandy View Post
I have noticed the same issue, buffeting with full right aileron but not with the left. I'm thinking the ailerons are positioned slightly different on the wing, which could also be causing my heavy left wing. I've followed Van's checklist for diagnosing and fixing a heavy wing as far as rigging is concerned and everything seems correct.
Possibly my right aileron is 1/32 lower causing a buffet and heavy left wing. I've installed a foam wedge (3 inches long 1/4 inch tall) under the right aileron to temporarily fix the heavy wing until I get all of the fairings installed.
Yes, that was my thought. However, they look pretty close in vertical alignment
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  #15  
Old 03-01-2014, 08:28 PM
crabandy crabandy is offline
 
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Location: Ottawa, Ks
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Mine appear to be spaced vertically the same referencing the aileron jig and tooling holes. (At least as far as I can measure) I'm hoping for some decent weather (6-8 inches of snow and ice tonight) so I can make my intersection fairings- test fly-possibly lower/raise an aileron soon!
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  #16  
Old 03-02-2014, 11:08 AM
petersb petersb is offline
 
Join Date: Mar 2008
Location: Toronto
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Quote:
Originally Posted by crabandy View Post
Mine appear to be spaced vertically the same referencing the aileron jig and tooling holes. (At least as far as I can measure) I'm hoping for some decent weather (6-8 inches of snow and ice tonight) so I can make my intersection fairings- test fly-possibly lower/raise an aileron soon!
Yes, weather her in Toronto is also bad. I checked my vertical alignment ny placing a straight edge on top of the wing and over the aileron, they look very close
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  #17  
Old 03-03-2014, 08:37 AM
pa38112 pa38112 is offline
 
Join Date: Mar 2008
Location: Clarksboro, NJ
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I have had this issue for a while, and was uncomfortable rolling because of it. This past Saturday I spend 1.5 doing rolls and perfecting my control inputs... No more buffeting. I was not applying the proper amount of rudder, and was pulling back ever so slightly on the stick while upside down. Depending on your arm positioning you could be doing the same one side VS the other.
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  #18  
Old 03-11-2014, 10:46 AM
zlinman zlinman is offline
 
Join Date: Oct 2010
Location: Arlington,Wa
Posts: 21
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A bunch of years ago we were flying competition in a 6 and 4. We decided we needed more roll rate, so we designed new bell cranks that would give us more down aileron. As I recall our deflections were 32 up and 25 down. Guess what! Faster roll and the buffeting was gone . Explain that to me. Aerodynamics are highly over rated.

Terry Burch
RV7 IO-375
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  #19  
Old 07-10-2017, 12:48 PM
ALMARTON ALMARTON is offline
 
Join Date: Mar 2010
Location: BRAZIL
Posts: 130
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Quote:
Originally Posted by pa38112 View Post
I have had this issue for a while, and was uncomfortable rolling because of it. This past Saturday I spend 1.5 doing rolls and perfecting my control inputs... No more buffeting. I was not applying the proper amount of rudder, and was pulling back ever so slightly on the stick while upside down. Depending on your arm positioning you could be doing the same one side VS the other.
I do have aileron buffet in both sides, and I do had a heavy wing issue that was "fixed" by the builder. But I did not know I need to use rudder in rolls with the RV7 I did not use rudder with my first plane that was a RV9. My impression is that this my new plane a RV7 rolls slower than my old 9 what to me is a disappointment.
Quote:
Originally Posted by zlinman View Post
A bunch of years ago we were flying competition in a 6 and 4. We decided we needed more roll rate, so we designed new bell cranks that would give us more down aileron. As I recall our deflections were 32 up and 25 down. Guess what! Faster roll and the buffeting was gone . Explain that to me. Aerodynamics are highly over rated.

Terry Burch
RV7 IO-375
Terry do you have any blue prints , plans or comments on how could I do this mod in a RV7, mine seems to roll pretty slowly (even compared to a 9) and is giving a buffet rolling either side.

I'd really want to fix this roll rate (increase it) and stop the buffeting. Anyone had it and got it improved/fixed could instruct me how would be of most help.
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Brazil
RV7A (8/2015 built by FLYER)
Lycoming 180 HP - YIO-360-M1B, Hartzell C2YR-1BFP/F7497 72, Garmin panel - G3X Touch, GTN650, GTS800, WX-500, BATT CONCORDE RG-25XC AEROBATIC SEALED.
-------------
Others: RV9A
Lycoming XIO320-D1A, Hartzell HC-C2YL-1BF/F7663-4 , CS GOVERNOR MTV-12-B, DYNON D180
AND GARMIN AVIONICS
(Sold with aprox 300hrs flown from Dec/2010 -- JUN/2014)
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