Landing gear

My tricopter is based on David Windestål’s most recent designs on RCExplorer, with a few tweaks and modifications of my own. I considered doing a build log, but there are already loads of those out there for this particular design, and I’d only have ended up doing something daft like getting epoxy resin on my camera lens.

Instead I’m going to write about the tweaks I made, and what worked (and didn’t) during the build and testing, starting with landing gear. I realise that it’s not the most exciting subject in the world, but several people have commented on the tricopter’s landing gear, so I figure that that counts as popular demand for a blog post.

To be honest, I didn’t expect that landing gear was going to be one of the trickier things to get right, but it turns out that it’s not completely trivial to find something that’s light and rigid, but with enough flex that it doesn’t just shatter on the rougher landings.

The solution I came up with is to use plastic coat hangers. They’ve worked really well, are easy to replace if they do break, are very light (each leg of the finished gear weighs 10g) and (I think) look quite good. Here’s a very simple parts/tools list and how-to:

landing_gear_parts

 

  1. Two plastic coat hangers. I got a pack of 10 from the local 99p store.
  2. 12 zip ties (4 for each arm). Use the small 2.5mm x 100mm type.
  3. RC fuel tubing  or surgical tubing. You’ll need 6 20mm lengths.
  4. A sharp knife.

Each coat hanger will make two bits of landing gear. Cut the coat hangers either side of the curved hook section, and again on the long straight edge. The easiest way I found to cut the coat hangers is to score them with a sharp knife, and use both hands to snap them away from you. If you’ve scored hard enough, that will give a nice clean edge. I also trimmed the little plastic hooks off the ends.

landing_gear_cut

 

Push lengths of fuel tubing over the ends of the coat hanger sections. You’ll probably have to twist them on, as it’s a very tight fit. The idea behind the tubing is to give the zip ties something to bite into; without them, the landing gear can slide up into your prop discs if you land too hard, and ruin your propellers (trust me on this!).

landing_gear

Attach the landing gear on to your tricopter’s arms using two zip ties at every point. Position the zip ties diagonally, so that they form an X on either side of the arm. Pull them fairly tight, so that they grip into the tubing, and trim off the ends. In a crash, the zip ties should break, saving the landing gear and tricopter arms.

landing_gear_attached

That’s it!

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