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Installing Rabe rudder on ARF Nobler

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Bob Reeves:
Thought it might be a good idea to retrofit my ARF Nobler with a Rabe Rudder. Mainly because it's going to be powered with a ST 46 and be swinging a large prop. If you haven't seen a Rabe Rudder Al Rabe came up with the idea way back when and has published several articles explaining what it does and how to set one up. Basically it counter acts the gyroscope effects of the prop in hard turns. Discovered installing a Rabe Rudder on a Nobler wasn't as straight forward as I first thought. The rudder is really too close to the elevator and you don't have allot of room between the elevator and rudder to work with.

Al says the elevator horn pivot should be on a 45 deg angle. I started by drawing 45 deg lines on a piece of paper and taping it to the fuselage side so I could draw a line on the elevator horn at a 45 deg angle from the hinge line. (Photo #1). I then drilled a couple holes along the line I drew on the horn and tapped them for a 2-56 screw so I could use a ball link at the elevator horn.

At first I was trying to use the real rudder to experiment with different control horns and linkages by taping a control horn to the rudder. This proved to be an exercise in frustration and almost gave up thinking it was impossible to make a Rabe Rudder work on this airplane. The rudder hinge line was just too close to the elevator hinge line and I didn't have enough room between the inside of the elevator and rudder for a control horn long enough to provide the desired rudder movement.

After sleeping on the problem, decided not to give up and made a sacrificial rudder from scrap balsa and started poking holes. After several tries finally found a combination I thought would work. Persistence pays off, as you can see in photo #2 my temporary rudder looked like swiss cheese before I finally settled on a control horn, linkage and location that would provide the proper rudder movement.

3rd photo is a test fit with actual rudder but still using the copper wire linkage from my test setup. Final photo is the actual linkage I will use. Will need to trim about 1/8 inch off the inside rear corner of the elevator to clear the quick link and put a couple washers on the inside of the ball link to space it further out from the control horn.

My reference was from a that Al Rabe posted on Stuka Stunt several years ago I saved to my hard drive. If I thought I could find the thread I would post a link but..........

Manuel Cortes:
Nice idea!!
Tell us how it works, when you fly it, please.
Regards.
Manuel.

Ron Merrill:
Bob, i am going to try it on my ARF Strega. With a 14x5 prop i think it will it. n~ Ron.

Bob Reeves:
The Strega will be allot easier, Wendy designed it for a Rabe Rudder from the get-go...

Greg L Bahrman:
Is this just a guess.....Or do you have experience with this setup and you know from passed experience that a Rabe Rudder is required. What is your definition of a large prop. I flew all my ST46's with 11 in. props. Be interesting to see how much better your Nobler flys than everyone else's.....Just trying to learn from those of you with more experience etc. Keep up the good work!!!

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