RC dolly for small planes (e.g. 3Dlabprint 1:12 warbirds)

thingiverse

It was always difficult for me to hand launch small low wing planes, like the warbirds found at 3Dlabprint (small Spitfire, ME 109, Mustang, etc.) On the other hand a fixed landing gear looks silly on these planes and so I always asked someone on our flying field to help me with launching. But this also means, that I could not fly my birds, when I was alone. A dolly would have been the solution. I didn’t want a huge one designed to launch big gliders, but a small one, which is dismountable and that does not need plenty of space either in the workshop or in the trunk of the car. I could not find anything anywhere. So I designed my own one, with all the specs I wanted to have. It’s small, solid and you can knock it down in a minute, if required. And it also has quite big wheels, in order to handle not so good grounds, too. A little advise: Many of these small warbirds do not have a rudder. So you can’t steer the dolly once it is rolling. If you recognize the dolly is going to break away, stop the launch immediately and go for a new attempt. Print instructions: 0.25mm resolution, 3 perimeters, 20-25% infill, support is needed for the small pin in front of the frame parts. All parts made from PLA except the tires. These are made from flex material like flexible PLA or TPU. Use about 15-20% infill for the tires and at least 4 top and bottom layers. The less infill, the more top and bottom layers and vice versa. Bed and printing temperature and print speed highly depends on your specific material. You can also use these as wheels, if you have no flexible material available: https://www.thingiverse.com/thing:2408047 Supposed to be fidget spinners, they also work very well as wheels for this dolly. Just glue a rubber band around their outer diameter to improve grip when rolling. There are two versions of the frame parts. One is for large printers with print areas from 250x200mm, the other one is for smaller printers with 200x200mm beds. The small printers version is just cut in half. You have to glue the front and the rear part together using 3 pins (infill=60%) each side for alignment. Wooden pins (6mm) can also be used. Note: I have not tested the small printers version, but I can’t see a reason why it shouldn’t work. BOM: 10x screw M4x20 (any head fitting any screwdriver) 4x screw M8x30 hex head 4x ball bearing 608ZZ 8x hex nut M8 (4 of them optional self-securing 10x hex nut M4 10x washers M4 (may not be needed, depends on your screws) 2x soft self-adhesive strips (optional) CA-glue (optional kicker) Assembly instructions See pics for the order of the parts. I think it’s self-explanatory. Put the M4 nuts into each hole of the braces. Mount the wheels by putting the M8 screws through the frame, put one M8 nut from the other side, tighten them, put on the wheels and finally another M8 screw (self-securing if desired). Tighten the last nuts slightly, so that the wheels can turn freely. Mount the braces and the frame parts together by putting M4 screws through the frame into the nuts installed in the braces before. Tighten them with a screwdriver. Use also washers, if the head of the screws are too small. The dolly has an adjustable stopper in the front. Put one M4 nut into the hole of each side of the frame. Take a M4 nut and turn it all the way up of one of the M4 screws. Put the screw with the nut into the knob and screw all together into the hole in the frame where you have put in the M4 nut before. To finish the dolly you can put some strips of any soft material (e.g. foam rubber) on the upper side of the frame, where the wings of the plane will rest. If the holes for the hex screws/nuts do not fit: 1. Holes too small – heat up the hex nut/head (not too much) and press it in. Let it cool down – done. 2. Holes too big – just glue in the nuts with some drops of CA glue. Put a drop of oil on a screw, mount the hex nut on the screw (only a few revolutions), put glue on the inner walls of the hole, press the nut with the screw all the way down and let the glue cure. The oil will prevent the screw sticking to the nut. If you feel the wheels are sitting not tight enough on the rims, secure them with some drops of CA glue. Have fun with it and let me know if you like it or not (and why!). Note: This is for private use only. Please respect license!