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Stabilizer angle of incidence

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 I have a new reproduction horz stabilizer and I need to use a good amount of trim tab deflection to fly level. It's not right so I'm going to change the angle of incidence. Right now it is at - 5.5 degrees. I'm going to shoot for the 3.5 deg on the TC. It's not a small project so I get it right the first time.

This topic was modified 1 year ago by Michael

   
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(@paxflyergmail-com)
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In-flight pictures? Is this based on flight test or something else?


   
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It's based on the position of the trim tab and indicator after flying. The tab should not be down as far as it is for straight and level flight.


   
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(@paxflyergmail-com)
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This is a tricky one. I would check your TCDS for deflection limits in elevator and tab. Make sure that is set first, very important. There are other tricks inflight to check including max nose up trim, where the airplane just sinks, does not stall, and you still have enough nose down trim to descend in the yellow arc. Now you are into the "cert world". Tread w caution, you may introduce "unintended consequences".


   
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(@aliebfriedearthlink-net)
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After you verify your tab angles to the type certificate, check your loaded CG compared to limits. If you’re at the forward or aft limits you can see max trim.


   
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Will Ware (Webmaster ISC)
(@stinsono)
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How do you adjust the stab? Got pics?


   
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 Success! The test flight went well. I still need to fiddle with the nose up trim tab adjustment. There is no  spec in the TCDS for the trim tab, so as James mentioned I will need to fly the plane more at slow speed. From my experience with this plane, 60-65 mph would be a  good speed for full nose up trim. The stall speed with full flaps is down around 40 something. The elevator is now only slightly up in cruise flight.

 The stabilizer is of course, all wood. I filled the 2 old  holes in the front spar with a dowel and re-drilled them 1/4" lower. There is a metal bushing in each one to prevent any crushing of the wood.


   
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(@paxflyergmail-com)
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Check here for TCDS Elev Tab limits. I never picked up which model you have? Looks like the 108-1/2 is different than the -3.

Here is a 108-3 example,

 

 


   
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 I have a Stinson 105 model 10, not a 108. There are no specs for the trim tab angle in the 10a Type certificate.


   
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