Elevator vs rudder control horn

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JimBob
Posts: 28
Joined: Sun Mar 05, 2017 4:09 pm
Location: Osceoal, IN

Elevator vs rudder control horn

Post by JimBob »

Made both the elevator and rudder horns per the plan.
Discovered that the tabs are made for 1” thick while the wood thickness they attach to is ⅝”.
Again per plan’s. I’m assuming that a1/8” piece of wood seems to fill in the gap just fine but curious why the plans have different dimensions.
Second question: also noticed that due to the smaller size of the elevator horn the cable will rub again the leading edge. Ok, so a reinforcement at that spot should work BUT when I trial fit the larger rudder horn on the elevator it raises the cable up enough that it (almost) misses the leading edge.
Is there a reason not to use a larger (rudder) horn on the elevator?
No doubt would change the force/feel at the stick but hey, we aren’t exactly flying F-16 here.
PoconoJohn
Posts: 165
Joined: Tue Jan 14, 2020 9:07 pm

Re: Elevator vs rudder control horn

Post by PoconoJohn »

I built my elevator and rudder horns with 1" tabs. If the tabs are 5'8", then the horn sits below the outer edge and have to think about fabric. Also, the point of the horn might impact the edge. Placing the tabs on 3/16" shims gets the horn above the fabric. I'm still new at this, so hopeful some experienced builders will comment.
Last edited by PoconoJohn on Wed Feb 02, 2022 9:32 am, edited 2 times in total.
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Richard Roller
Posts: 240
Joined: Mon May 22, 2017 11:14 am
Location: Olathe, Ks.

Re: Elevator vs rudder control horn

Post by Richard Roller »

Rubbing against the leading edge of the horizontal stab is a common occurrence. If you build to the plans it is going to happen. Several builders, including the builder of N34KP have raised the bellcrank behind the pilots seat up to gain cable clearance. It is a minor thing and in the case of N34KP has worked well for 20+ years. Of course there are lots of Piets flying with a rub strip on the outside of the stab in that area.

As far as the rudder/elevator horns go, looking back through my pictures people are putting a plywood pad under the tabs. It would seem that 3/16" would do the job.
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KenBickers
Posts: 128
Joined: Tue Mar 07, 2017 7:00 pm

Re: Elevator vs rudder control horn

Post by KenBickers »

I raised the bell crank 2 inches to avoid the Piet rub. That allows the elevator cables to clear the horizontal stabilizer. The tradeoff is that this requires that the cables running from the cockpit controls have to make a sharper bend to join the bell crank. I added a pulley for the cable that goes to the top of the bell crank. Every change from the plans has a ripple effect.

Enjoy, Ken
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