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  #1  
Old 02-28-2014, 05:49 PM
petersb petersb is offline
 
Join Date: Mar 2008
Location: Toronto
Posts: 324
Default Aileron "snatch"--buffett

After searching the forum there are two suggested reasons published.

1: Aileron leading edge causing flow separation

2: Trailing edge radius.

Which is it ?

I have aileron buffet in a right roll and none in a left roll, strange.

Ailerons look identical in trailing edge roundness, vertical alignment, bell crank position.

Of course I know it is not critical, however, being an experimental aircraft I would like to experiment and identify the cause for my own satisfaction
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Last edited by petersb : 02-28-2014 at 05:59 PM.
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  #2  
Old 02-28-2014, 06:07 PM
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N941WR N941WR is offline
 
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Could it be that you aren't getting the same amount of aileron deflation?

I can see your left leg restricting your stick movement when rolling left. When rolling right, you have more room to move your right leg out of the way.

Just a thought.
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  #3  
Old 02-28-2014, 06:11 PM
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Snowflake Snowflake is offline
 
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I get the buffet both ways if my entry speed is too high. Try dropping 5mph and doing it again?
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  #4  
Old 02-28-2014, 06:13 PM
petersb petersb is offline
 
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Quote:
Originally Posted by N941WR View Post
Could it be that you aren't getting the same amount of aileron deflation?

I can see your left leg restricting your stick movement when rolling left. When rolling right, you have more room to move your right leg out of the way.

Just a thought.
Good thought, but I think I was applying equal stick deflection. Infact, my impression is the right roll buffet occurred with just over half stick deflection, it seemed to be much less deflection than my previous RV6 required before it buffeted
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  #5  
Old 02-28-2014, 06:39 PM
petersb petersb is offline
 
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Quote:
Originally Posted by Snowflake View Post
I get the buffet both ways if my entry speed is too high. Try dropping 5mph and doing it again?
I was doing 140 mph

My real interest was to determine why is there a difference between the left and right roll in regards to buffet and no buffet
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Last edited by petersb : 02-28-2014 at 06:42 PM.
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  #6  
Old 02-28-2014, 08:46 PM
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RV7A Flyer RV7A Flyer is offline
 
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Isn't "aileron snatch" different than the aileron buffet felt during rolls at higher entry speeds? (Just FYI...I'm certainly not an expert in *anything* related to aerobatics ).
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Old 02-28-2014, 08:54 PM
petersb petersb is offline
 
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Quote:
Originally Posted by RV7A Flyer View Post
Isn't "aileron snatch" different than the aileron buffet felt during rolls at higher entry speeds? (Just FYI...I'm certainly not an expert in *anything* related to aerobatics ).
Yes, I used both "snatch" and "buffet" in the heading as many people are using either word to describe the same condition. It is really buffet
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  #8  
Old 03-01-2014, 07:21 AM
Lindamon Lindamon is offline
 
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I get the buffet either way I roll. I'm not sure why you only get it one way. It's possible you may be deflecting the stick more in a right roll if you are using your left hand on the stick. If you are rolling with your left hand on the stick, your arm muscles work better for a right roll, it takes a lot less effort to push away to the right than to pull left on the stick, especially against the air pressure on the ailerons at speed. Try rolling with your right hand and see if the opposite happens. The aircraft doesn't seem to roll any faster if I give it full aileron anyway, so I just do about half as others have mentioned.
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Last edited by Lindamon : 03-01-2014 at 07:29 AM.
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  #9  
Old 03-01-2014, 07:23 AM
RVDan RVDan is offline
 
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Aileron snatch is when aerodynamic forces move the aileron against your command. It feels like someone grabbed the aileron and applied force. If you are holding the stick lightly it will move. Buffet is an oscillation in the airflow that creates a vibration or shaking that doesn't really displace the overall deflection of the aileron.
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  #10  
Old 03-01-2014, 07:36 AM
petersb petersb is offline
 
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Quote:
Originally Posted by RVDan View Post
Aileron snatch is when aerodynamic forces move the aileron against your command. It feels like someone grabbed the aileron and applied force. If you are holding the stick lightly it will move. Buffet is an oscillation in the airflow that creates a vibration or shaking that doesn't really displace the overall deflection of the aileron.
Yes you are correct, I used "snatch" as it seems to be the generic term used in the forum
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