RC Aircraft Wheel Brake System

thingiverse

I was fed up with my 2m span, 50cc petrol CAP 232 RC Aircraft rolling on tickover so decided that she needed a braking system. I designed this system to fit inside the wheel spats and it allows proportional braking. The spat on my CAP is about 220mm long, as shown in the photo, and the system fits well. (obviously 'cos I designed it to fit!!) It would probably fit inside a smaller spat if needed, and you could probably reduce its size for some of the smaller nano servos for a smaller aircraft.Inside the plunger inner and outer assembly there is a spring stolen from a retracting ballpoint pen. The return spring on top is from my junk drawer. It is designed for a micro servo 24mm x 12mm. You obviously need one for each wheel and this only really works if you have spats of sufficient size.The servo horn fits on top if an existing circular servo horn with a couple of self tapping screws.The servo wire will fit snugly in the chanels down the side and underneath on either side for left and right brakes.The down side of this relatively simple system is that the external brake plunger rubs on the wheel in a decidedly primitive fashion to provide the braking, but I figure that by the time I need a new tyre, I will have probably long ago crashed the plane, so it wont be a problem. I can hear the Boeing execs saying "Why didn't we think of that?"There are two screw holes in the bottom of the body, and a couple of servo screws secure the system to the rear of the spat as can be seen from the photo.Print the body with about 20% infill; the servo horn, plunger inner and outer with 100% infill.So does it work? In a nutshell, Yes. it certainly provides stopping power when waiting to take off at the threshold. You will have to play around with the position of the system to achieve reliable braking. I changed the length of the Inner part of the plunger to achieve the same 'rest' distance from the wheel on each side. With some careful adjustment, you can use it to stop your aircraft on the roll out as well. the difficulty comes in achieving the same amount of braking on both sides. As such, I use two spare channels which are linked, and each can be adjusted seperately in terms of trim and throw.All in all its much cheaper than the proprietary electromagnetic systems and easy to replace in the event of catastrophe.