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  #11  
Old 10-14-2017, 05:39 PM
gossend gossend is offline
 
Join Date: Dec 2011
Location: Georgetown, Texas
Posts: 151
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This falls in the large basket known as "unintended consequences of alterations to a perfectly good design"

My aircraft is a highly modified EAB "sorta RV-12" homebuilt.Most of the 100 or so mods I made have worked out well, and I had great fun making them and proving them out.
One of my mods was an aileron trim system, in which I embedded a tiny (two oz) linear actuator from the RC model world into my right flaperon, and used it to drive a trim tab which is a 2"x 8" hinged tab mounted on the trailing edge of the flaperon. Works great, and I get a kick out of watching the Garmin G3x system auto-trim the aircraft in cruise at any speed!
What I missed is the fact that a trailing edge tab will act as an anti-servo tab when the flaperons are deflected. In fact, it induces a noticeable roll to the right that does not go away as long as the flaperons are deflected. (-obviously, since the tab will exert a force to raise the right flaperon just a smidgen - which produces a significant and residual roll to the right!)

Solution: Install an identical, but fixed tab on the other side. Now the tabs cancel each other out when you deploy "flaps" and you go down final hands-off!
Test flew this today
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Dick Gossen
gossend@gmail.com
Flying: EAB RV-12 with G3x Touch
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  #12  
Old 10-14-2017, 05:43 PM
gossend gossend is offline
 
Join Date: Dec 2011
Location: Georgetown, Texas
Posts: 151
Default Response to the comment that's surely coming:

Yes, I added a bit of weight to the flaperon nose tube to balance out the added mass of the trim system
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Dick Gossen
gossend@gmail.com
Flying: EAB RV-12 with G3x Touch
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  #13  
Old 10-14-2017, 07:55 PM
RV8JD's Avatar
RV8JD RV8JD is offline
 
Join Date: Jan 2005
Posts: 477
Default

Quote:
Originally Posted by gossend View Post
This falls in the large basket known as "unintended consequences of alterations to a perfectly good design"

My aircraft is a highly modified EAB "sorta RV-12" homebuilt.Most of the 100 or so mods I made have worked out well, and I had great fun making them and proving them out.
One of my mods was an aileron trim system, in which I embedded a tiny (two oz) linear actuator from the RC model world into my right flaperon, and used it to drive a trim tab which is a 2"x 8" hinged tab mounted on the trailing edge of the flaperon. Works great, and I get a kick out of watching the Garmin G3x system auto-trim the aircraft in cruise at any speed!
What I missed is the fact that a trailing edge tab will act as an anti-servo tab when the flaperons are deflected. In fact, it induces a noticeable roll to the right that does not go away as long as the flaperons are deflected. (-obviously, since the tab will exert a force to raise the right flaperon just a smidgen - which produces a significant and residual roll to the right!)

Solution: Install an identical, but fixed tab on the other side. Now the tabs cancel each other out when you deploy "flaps" and you go down final hands-off!
Test flew this today
And you didn't feel the need to mention your modification in your first post asking for help??? Sheesh!!

From now on when someone has an issue, the first question needs to be, "What mods, if any, did you make to the design?"
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Arlington, WA (KAWO)
RV-8, 210 Tach Hours
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RV-8, 1932 Tach Hours
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Glasflügel H-201B Standard Libelle, N564NS - Sold
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  #14  
Old 10-16-2017, 09:37 PM
gossend gossend is offline
 
Join Date: Dec 2011
Location: Georgetown, Texas
Posts: 151
Default Re: Sheesh

Yep, guilty.
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gossend@gmail.com
Flying: EAB RV-12 with G3x Touch
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