I got a new radio last week and decided to retrofit my Super Cub with a couple of 3-wire servos and add ailerons. I pulled the servos out of my Mini LST truck and my RC18T. I don’t know what kind the MLST ones are, they are pretty small, smaller than my HS-81MG, about 0.9″ x 0.9″ and probably about the size of the HS-55 servos. But they work perfectly for ailerons. I fixed the rudder with the stock servo, and installed the HS-81 for the elevator. If I had another servo, I would also run the rudder, but for now it’s just fixed and flies just fine without it.
I measured and cut the ailerons with a razor blade 12″ x 1.75″ with the inside edge 7″ away from the center of the wing. I bought a set of replacement control horns for the SC and installed them in each of the ailerons (the same ones that go into the rudder and elevator). The pushrods are 0.047″ diameter steel which I just bent into a “S” in each end and fit into each of the control arms and servo horns. There is no mechanical adjustment this way, so I just made sure that the servos were dead center with the trims on the radio at +/- 0 and then bent the ends just perfectly. I messed up one, so I just redid it and then with my radio I dialed in each servo so they were completely flush.
I used tape for the aileron hinges which as far as I can tell is simple, effective, and works great. When cutting away the notch for the aileron to rotate up/down, make sure you do it in the underside of wing and not the top-side of the wing or in the aileron. You want to maintain a nice smooth airframe on the top of the wing. I cut cutouts in each wing just the size of each servo and taped over them to hold them in place. Each servo runs to its own channel on the radio, and then I use a setting called Flaperon. With the switch down, I’m in normal aileron mode where each aileron opposes the other at all times. Then I can flip the Flaps switch up and both ailerons are thrown down, perfect for making great landings and takeoffs. Let’s see a single servo aileron setup do that! This also allows me to fine tune each aileron since I don’t have any mechanical adjustment in this area. This new radio is sweet, it can do so much. It’s a Futaba 6EXP by the way. I plan on doing a write-up on it later, but my first impressions are this is a great radio.
After I got everything installed and the ailerons working, I was testing it out when all of a sudden the stock 480 motor just died. I tried running straight off a couple of volts and it was just dead. So I did a quick replacement with my old Speed 480 BB Race motor. Though my past experience suggests this isn’t a great motor for the SC, I had to give it a shot because I wanted to try out my cool aileron mod.
And so this morning the wind was calm so I took her out for her first flight with the new radio, ailerons, new ESC, and the new Speed 480 motor. I checked all my trims, checked for proper movement of everything and gave her a throw. I quickly realized that my elevator servo was reversed – up was down and down was up. Ooops! I was so busy making sure that the ailerons were moving properly that I completely overlooked making sure the elevator was moving properly. I made an attempt to land while instantly trying to retrain myself and not throw the plane straight into the ground. I managed to bring it sound safely thinking to myself how did I miss that?? I reprogrammed my radio and a minute later had the elevator moving up and down properly as it should. At least it was turning left and right the way it should. So I gave it another toss and she flew perfectly. The plane definitely handles differently without the rudder. The plane gets sideways really easily when turning but still handles great. I’ve been practicing my barrel rolls, which though this plane can do, it’s doesn’t do them very well. The new motor lacks much power, so the plane feels kinds slow, but the ailerons work great and it feels like a completely new plane and it’s still very easy to fly. Now I just need to work on my power options, maybe go brushless?
So here’s a few pics and some video.