G’day All,
I needed a new challenge, sports’ flying was getting boring, and, I do not like the idea of ARFs all that much. Now, I'm not giving up the sports flying, I just needed a new interest and get back into scratch building. Single channel had been something I had always had sitting in the back of my mind. Back in the early 70s I was given a “C & S” 27meg transmitter and receiver with a Babcock MK11 rubber powered escapement, the problem then, was that I had no idea what I was doing, got disillusioned with the radio because nobody in the local club had flown SC, I gave in and gave the radio away and purchased a Futaba 5 channel proportional set, and I’ve been flying proportional radios ever since.
Now, over the last few years I had an idea of building a model with just rudder only using my proportional radio to see how it was to fly single channel, I googled “single channel RC aircraft” to see what was available in vintage plans for SC aircraft. I found this website… http://www.singlechannel.co.uk/ … this site peaked my interest, read the whole site, watched all the videos and found out how to make a transmitter that worked almost the same as the early single channel radios.
Phil Green, from singlechannel.co.uk manufactures a PIC based board that connects to a standard modern 2.4Gig transmitter module. The board makes the transmitter which has a single control (a push button) that operates three servos and makes the servos emulate the rubber powered escapements. The original SC radio gear could operate rudder, kick up elevator and a 2 or 3 position throttle, all with a single push button. Phil’s board does a great job, the rudder servo follows the sequence of a rudder escapement, push and hold the button once and the rudder turns right, release the button and the servo cycles through full left and back to centre just like an escapement, and the rudder servo cycles through right and left rudder as you go up and down the throttle. See the short video later in the post.
The Sniffer with the dihedral removed.
My first aircraft I chose for the new SC radio was a free flight kit by Midwest I built over 20 years ago called the Sniffer, 29” wing span and I had a .75 diesel in it. The Sniffer was slowly falling apart on a shelf in the shed, I stripped the shredded tissue and recovered the flying surfaces with Solarfilm, made sure the tips had washout and replaced the diesel with an electric outrunner and a single servo on rudder with the torque rod drive to the rudder and a bird cage setup on the rudder (see the photos). The first launch, she climbed away dead straight at 50’ I gave the command to turn right and the Sniffer rolled inverted and dived into the ground. Lucky the Sniffer is light; the only damage was a prop and a crack in the rear fuselage, ready to fly in 5 minutes. Back to Google, I came up with the term dutch roll and found that there is such a thing as to stable. The Sniffer has a polyhedral wing; all I had to do was take out the centre dihedral.
The bird cage assembly.
First flight after the fix, beautiful climb out at half throttle, again first command right rudder slight right banking turn release button and she levels out, next command left rudder, left bank turn held rudder in a little to long and the nose dropped in the turn, released the rudder she leveled out and started to climb again, remember that for later flights. The flight lasted 8 minutes, flying left and right hand circuits, figure eight course with the cross over straight overhead and landing 20’ from where I hand launched. Back to the dive when you hold rudder to long, it’s a great way to gain speed, I found that one or two turns in a spiral dive level out nose into the wind and as the nose comes up give right rudder and you get a barrel roll. I also tried just pulling out of the dive without the rudder and got an almost loop. I’m having a lot of fun with this SC challenge, getting the brain working figuring out how to get these models to work. Next is to fit an original rubber powered escapement, Phil has an add-on circuit that works with the modern radio gear between the RC and the escapement, more on that on a later date.
Outrunner fitted, the hole was for the diesel's exhaust.
Information gathered for setting up the RC gear and aircraft came from “Phil & Shaun’s Single Channel & Vintage RC Page”, RC Groups, RC Universe, Outerzone Plans Page, Youtube and a few other web sites I forgot their names. The info is out there you just have to find it.
The single push button control.
This is a video of the radio working.
http://www.youtube.com/watch?v=CaQcjNiDMo8&feature=share&list=UUMl0PrDg2GLCrFZtxyWg7sQ