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  #11  
Old 05-15-2017, 08:45 AM
slngsht slngsht is offline
 
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Location: Purcellville, VA
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I replaced one rudder skin

while you're at it - since your first rudder is almost done, inspect it for oil canning. something I didn't notice I had until it was too late. I'm living with it until she is flying since it's a common issue, but may look into a new rudder some day.
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  #12  
Old 05-15-2017, 08:49 AM
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bkervaski bkervaski is offline
 
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Quote:
while you're at it ... inspect it for oil canning
It did have some very minor oil canning .. not sure how to avoid it with the way this part goes together ..
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  #13  
Old 05-15-2017, 09:06 AM
slngsht slngsht is offline
 
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I think there is a way - I will try it next time. (everything i'm saying is about my RV-7. no idea if RV14 is similar)

First, have you laid your rudder down to see if it is perfectly symmetrical? i.e. if you lay it down flat on a table, does the trailing edge lay flat? or is it off the table? if you flip it over, is it off the table by the same amount? or also flat? check top and bottom.

If the answer is no, I'm thinking that could be the cause of any oil canning. I saw a while back someone made a jig to make sure the rudder was symmetrical as they assembled.

I'm no expert builder. so take everything with 2 grains of salt.
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  #14  
Old 05-15-2017, 09:20 AM
slngsht slngsht is offline
 
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Location: Purcellville, VA
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here you go - found the post I was talking about. Hopefully this is useful

http://www.vansairforce.com/communit...13&postcount=8
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  #15  
Old 05-15-2017, 03:50 PM
Bobo Bobo is offline
 
Join Date: Nov 2016
Location: Aurora, OH
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One technique (among many I'm sure) to ensure a straight trailing edge on control surfaces is to cleco a piece of angled aluminum (match drilled) to the trailing edge as the epoxy cures over several days. To make sure the angled aluminum does not epoxy itself to the trailing edge, a piece of heavy duty tape was stuck to the angled aluminum and the side going against the rudder was brushed with a mold release. After 3 days of epoxy curing the clecos were removed and the angled aluminum released very easily.
I'm a first time builder and no expert to be sure but I was taught this at Synergy Air which has used this technique over hundreds of builds of different RV models. The angled aluminum was match drilled many builds prior to my build, I just used it. This deviates from how the plans direct it be done, but a very straight trailing edge was achieved on the rudder and both elevators. You can see some pics of this process for the rudder on my blog dated 14 March.
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  #16  
Old 05-15-2017, 06:36 PM
slngsht slngsht is offline
 
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Quote:
Originally Posted by Bobo View Post
One technique (among many I'm sure) to ensure a straight trailing edge on control surfaces is to cleco a piece of angled aluminum (match drilled) to the trailing edge as the epoxy cures over several days. To make sure the angled aluminum does not epoxy itself to the trailing edge, a piece of heavy duty tape was stuck to the angled aluminum and the side going against the rudder was brushed with a mold release. After 3 days of epoxy curing the clecos were removed and the angled aluminum released very easily.
I'm a first time builder and no expert to be sure but I was taught this at Synergy Air which has used this technique over hundreds of builds of different RV models. The angled aluminum was match drilled many builds prior to my build, I just used it. This deviates from how the plans direct it be done, but a very straight trailing edge was achieved on the rudder and both elevators. You can see some pics of this process for the rudder on my blog dated 14 March.

I did this technique. while it guarantees the trailing edge is straight, it does not guarantee it's in the same plane as the centerline of the spar.
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