Wing Rudder using 9g servo for tricopter updated.

I was making a streamlined Quad arm to try and make it more efficient and stable when I suggested using a rudder for yaw control in a tricopter.  A couple of people told me that it had been done before but with limited success. I wanted to know if it could be done using a 9gram servo instead of a servo mounted motor to save weight. I`d already made an aerofoil shaped faring to slip over a quad arm so I decided to give it a go and see if I had any better look.

I used a cooling fan for the bearings and just two arms for the motors so I could balance out the weight. I was going to use two rudders to start with because I was warned that it might not be very responsive. Well as it turns out I only needed one. Tomorrow morning I`m getting some digital scales so I can measure exactly how much yaw there is and at what throttle and through rates. I extended the servo arm to get more out of it. For a cheap nylon threaded servo I think it did quite well. I think I could get away with even smaller metal geared servo.

Well, the proof of the pudding is in the eating as they say, so all this doesn’t really mean anything until it`s been tested on a tricopter. I`ll edit this posting tomorrow when I get the scales and maybe someone will be able to tell me if it`s useful or not.

Here’s the update. I made a rig similar to a thrust tester only scaled down a bit. I managed to measure the yaw at low, medium, 75% and 100% throttle and the throw from 0 to 100%. I think the rudder shape could do with some refining, the camber`s not quite right and it`s probably too deep as well. I’ve got hold of some thin, lightweight carbon fibre tubing. So there’ll have to be a few changes anyway. Apart from one or two snags I`m pleased with the way it`s going I`ll do an update when I`ve got it sorted. Thanks for your comments.