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Trim tab on a Kitfox 4???

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Posted

Working a little bit on the Kitfox 4 I'm rebuilding. Basically I have to sandblast the tailfeathers and controls, repaint them and then start reassembly. I peeled off the fabric on the trailfeathers a couple of days ago. There was an add on adjustable trim tab on the elevator. The hinges were pop riveted in place on both ends of the tab. Now get this... 3/16" aluminum rivets were used, and to top it off, when the guy drilled the holes, he went through both sides of the 3/8" tube. Took half the material away even though the rivets didn't go through the inner hole. Makes you wonder what goes through some people's minds at times. Anyway, got to get some welding done to patch it up. I got thinking, why not add a built in trim tab while I'm at it. Those of you who are flying Kitfox 4s, would you do it? If you don't have a trim tab, do your wish you did? Any body got any pics of theirs when they did? Thanks, JImChuk

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Posted (edited)

Jim,  I've got a built-in trim tab off of a Kitfox that had electric trim - Maybe I can get a photo tomorrow for you.  I built Foxy Flapper with openings in both elevators for trim tabs.  One is automatic for flaps.   I think they are about 24" long, but have to measure chord.  EDMO

Edited by EDMO

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Posted

Best mod I did to my B model. 

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Posted

Jim,  Would drawings from a Kitfox 4 manual help you?  I haven't checked mine, but it should be there.  EDMO

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Posted

I have the trim tab on my Avid MK IV.  Got it locked solid now though with a 3/16"  bolt and fender washers top and bottom.  Last summer right after I started flying the plane after the rebuild, the cable broke and had just a bit of flutter with the tab flapping up and down.  I had bought the heavier sized piano wire and couldn't get it around the bends the outer cable went through.  Ended up reusing the old cable and it only lasted for a few flights.  Have to add that to the next order.   Usually, I just had the trim set so it would fly hands off, never used trim for landing.  JImChuk

PS  Don't think I will find anything in the Kitfox 4 manual (I have 2 of them) as the Kitfox 4 didn't have a trim tab.  Thanks though for the offer Ed

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Posted

I have the trim tab on my Avid MK IV.  Got it locked solid now though with a 3/16"  bolt and fender washers top and bottom.  Last summer right after I started flying the plane after the rebuild, the cable broke and had just a bit of flutter with the tab flapping up and down.  I had bought the heavier sized piano wire and couldn't get it around the bends the outer cable went through.  Ended up reusing the old cable and it only lasted for a few flights.  Have to add that to the next order.   Usually, I just had the trim set so it would fly hands off, never used trim for landing.  JImChuk

PS  Don't think I will find anything in the Kitfox 4 manual (I have 2 of them) as the Kitfox 4 didn't have a trim tab.  Thanks though for the offer Ed

Jim,  I just checked my KF4-1200 manual and it does show a built-in electric trim tab, like the one that was on my KF2.  One thing I noticed on the drawings is that the hinge folds from the top side - I think this might be a mistake, since you get better down travel with the hinge at the bottom of the elevator, although it could disrupt the air flow when the tab is down?  EDMO

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Posted

Thanks for the info Ed.  I'll have a look at my manual.  I was thinking about welding in hinges like are used on the elevator.  One near each end of the trim tab with 1/8" pins.  I should have looked at my manual before I posted this question.  I see that the trim tab feature was an option on the 4.  JImChuk

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Posted (edited)

Thanks for the info Ed.  I'll have a look at my manual.  I was thinking about welding in hinges like are used on the elevator.  One near each end of the trim tab with 1/8" pins.  I should have looked at my manual before I posted this question.  I see that the trim tab feature was an option on the 4.  JImChuk

They used piano hinges.  May have been an option on KF2 - I haven't checked my KF3 for one.  EDMO

Edited by EDMO

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Posted

I added a tab to the much modified elevator on the Mangy Fox.  (IV-1200 Classic)

post-36-13615770368203.jpg

 

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Posted (edited)

I guess Big Elevator Envy is like Big Tire Envy!  ;<)  I made mine bigger too!  :BC:  EDMO

Edited by EDMO
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Posted (edited)

Well I bit the bullet and started cutting.  Figured I had to take care of the big holes the other guy drilled in the elevator anyway, so some more welding wouldn't hurt.  I can tack everything together and then I take it to a guy who tig welds it up for me.  Fabrication takes the longest anyway.  Just about ready to take to him.  Last pic is the other side of the elevator, but it could just as well have been a "before"  picture.   JImChuk

 

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Edited by 1avidflyer
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