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  #1  
Old 11-04-2014, 04:48 AM
Selma Selma is offline
 
Join Date: Oct 2010
Location: Berlin, Germany
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Default Rudder balance

Hi guys,
what would you think? Is it necessary to balance the rudder?
Thanks for your consideration.

Pit
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  #2  
Old 11-04-2014, 09:49 AM
jfogarty jfogarty is offline
 
Join Date: Sep 2005
Posts: 119
Default

Follow the directions on the plan, I don't remember doing anything special.

Jim Fogarty
RV9A N492RV
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  #3  
Old 11-09-2014, 01:50 PM
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KRviator KRviator is offline
 
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Quote:
Originally Posted by Selma View Post
Hi guys,
what would you think? Is it necessary to balance the rudder?
Thanks for your consideration.

Pit
Definitely Yes. I am not privy to the flutter analysis for the -9's, but at the speeds we fly, an unbalanced control surface would be much more susceptible to it.
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  #4  
Old 11-14-2014, 01:04 PM
Rupester Rupester is offline
 
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I think rudder balancing is unnecessary. It's not called for by Vans and I never gave it a thought. Of my six or seven good friends who built RVs, none of them balanced the rudder .... and none of us have had any issues.
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  #5  
Old 11-14-2014, 08:13 PM
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grubbat grubbat is offline
 
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Location: Ga
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Default Balance

Hummm, it's in the plans for the -7, -8, -9, -10. Etc. I would think that Van's may know something about the subject if they put them in the plans.


Quote:
Originally Posted by Rupester View Post
I think rudder balancing is unnecessary. It's not called for by Vans and I never gave it a thought. Of my six or seven good friends who built RVs, none of them balanced the rudder .... and none of us have had any issues.
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  #6  
Old 11-18-2014, 03:12 PM
krw5927 krw5927 is offline
 
Join Date: Aug 2010
Location: Wichita, KS
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Quote:
Originally Posted by grubbat View Post
Hummm, it's in the plans for the -7, -8, -9, -10. Etc. I would think that Van's may know something about the subject if they put them in the plans.
Don't see it in the plans for the -9. Do you have a reference?
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  #7  
Old 11-18-2014, 04:57 PM
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grubbat grubbat is offline
 
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Default Counterbalance skin and weight

For the RV-9, it would be located on page 6-4 in the section "BUILDING THE RUDDER SKELETON" about three paragraphs from bottom. Drawing 7 should show the weight placement.

Control surfaces (rudder & elevators) should be in trailing position after final fitting and painting.
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  #8  
Old 11-18-2014, 05:56 PM
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Kevin Horton Kevin Horton is offline
 
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Location: Ottawa, Canada
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I think that some of the people posting on this thread have different understandings of the question "is it necessary to balance the rudder?"

Some people read that question as meaning "is it necessary to add sufficient balance weight so the rudder is balanced about the hinge line, just like the elevators?"

Other people read that question as meaning "is it necessary to install the balance weight that Van calls for in the plans, or can I safely leave it off?"

Build the rudder with the balance weight that Van's supplies. They have done the engineering and flight testing to show that the supplied weight provides adequate flutter protection. There is no need to add additional weight so the rudder is 100% balanced.

On the other hand, if you leave the weight off, you have no idea whether the rudder will flutter inside the approved speed envelope, or not. Flutter, if it occurs, will likely lead to loss of the rudder and possibly the VS, likely leading to a fatal accident.

Build the aircraft as called for in the plans.
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  #9  
Old 11-18-2014, 06:16 PM
krw5927 krw5927 is offline
 
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You're exactly right, Kevin. I became concerned when I perceived others as saying that the rudder should be neutrally balanced about the hinge line as the elevators are. There is no mention of this in the plans.

Yes, my rudder has the drawing-specified balance weights installed, but I never did check for neutral balance. As far as I can tell, neutral balance is not required by the plans.
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