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Building Tips and technical articles. => Building techniques => Topic started by: sadams714441 on February 27, 2007, 08:07:58 PM
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Does anyone have pictures or can you tell me how to make the outboard trim tab moveable, and how do you hook it up? Have my wing pretty much built except for this outboard tab
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On my vector ARF i literally broke it off and sanded the trailing edge of the wing smooth the put a single hinge and connected a control horn on the wing tip with a 2 inch pushrod connected to the trim tab with a adjustable clevis
hope this helps
Steve
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Tom Morris sells a little device for this - works on rudders and trim tabs.
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One hinge is enough to hold it on ok? With adjustable link ? Then inbed horns in wing tip and on adjustable piece?
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One hinge is enough to hold it on ok? With adjustable link ? Then inbed horns in wing tip and on adjustable piece?
I usually use two hinges.
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Does anyone have pictures or can you tell me how to make the outboard trim tab moveable, and how do you hook it up? Have my wing pretty much built except for this outboard tab
Steve,
Here is an idea for you to work from. There is nothing critical about the tab, so you can engineer it to fit your needs.
This is a moveable rudder on a Southwick "Skylark", but the principle can be use for your wing tab.
My criteria was to have the assembly removeable for finishing, minimum size for appearance, and to use 'pin-less' hinges to dampen any flutter or vibration.
One feature is that the "zee" bend goes through a 1/16" piece of plywood that is flush with the surface. The reason being, of course, is to have a smooth surface for finishing. I used a Dubro #180 ball link for the adjustable end, and that is threaded/glued into a short piece of 1/4" diameter dowel that is recessed into the surface. You can adjust the length of the dowel to give you the moment arm necessary for the amount of travel you need. You could use a clevis, but the ball link is small, and perhaps will not vibrate as much. However, a clevis would allow 1/2 turn adjustments, whereas the ball link can only be adjusted in full turns.
Another feature is, because the surface is only "adjustable", it does not have to flex freely, so you can use the "pin-less" hinges that that see in the photo. You DO want at least two hinges.
Post a picture for us, so we can see what you ended up with.
Cheers,
Warren Wagner
p.s. It's 81 degrees here in Bradenton, Fl, however, it's too windy to go flying !! :-(
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I once tried using a link to adjust a wing tab, another time a rudder. Seems I found a way to get some turbulence that caused additional problems. I switched to using small Dia. brass tubes installed into the hinge position. They acted as ground adjustable non-movable hinges. Just bend to where I wanted the tab to be, and they stayed there until I re-adjusted them later.
John
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Why couldn't a fella use little sheet metal tabs, same size as those hinges, and just hand-bend them to whatever angle you want? No external mechanism at all. As you say, by its very nature they wouldn't have to bend much, or very often. K.I.S.S.
--Ray
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I've never had any luck with adjustable tabs on the wings. While they work, as noted, other problems are created.
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Why couldn't a fella use little sheet metal tabs, same size as those hinges, and just hand-bend them to whatever angle you want? No external mechanism at all. As you say, by its very nature they wouldn't have to bend much, or very often. K.I.S.S.
--Ray
Hi Ray,
It does work, but there is a chance of bumping the alignment out of whack. To keep it "soft" enough to bend without breaking ny structure, it's soft enough to get accidently moved.
Bill <><