Intro: How to Build Custom Multicopter Landing Gear
My previous 'ble focused on making a Multicopter frame but now you want to make landing gear for the frame you just built, right?
Carbon-fibre or glass-fibre landing gear is either lightweight and expensive, or slightly less lightweight and slightly less expensive – and may not easily fit your custom frame. This instructable aims to give you other alternatives; durable, light alloy undercarriages that can be made to fit your particular build and camera (or lack of).
Best of all, the materials cost for these designs is so low you can even built a couple and prototype!
Step 1: Materials (and Tools)
2mm flat alloy bar (width depends on frame size and weight)
1.2 to 1.6mm angle alloy (size depends on weight and size of frame)
M3 or M4 bolts & nylocks
Washers to fit bolts
2mmx25mm flat alloy plate – reinforcement for larger craft only, the same stuff is used for the motor mounts in my Frame building ‘ble
1/10th RC car bodyshell clips (depends on leg design)
Step 2: Design
As can be seen in the images above, there are a couple of different landing gear designs that you can make and they vary in complexity and application.
The Green/Black quad’s Ski –style landing gear supports around 3kg with 12mmx2mm arms and 10x10x1.2mm angle alloy for the skids. On a basic level, you simply decide the height of the landing gear (based on the size of the gimbal you’re using) and factor in a 25 degree angle (off vertical). Now you know how long the extended part of your arms needs to be!
Rather than try and achieve a nice even curved bend like that on a Phantom’s landing gear, I opted for a simpler design with two sharp bends and a straight leg (see image).
The Hex’s landing gear had the skids and legs measured, and the braces for the top and bottom (the 2mm flat bar) were measured and replicated, then the legs were attached to the centre of the skids with stainless M4 hardware. It was a requirement for this system that a 3 Axis DSLR gimbal could be attached between them, and still have 50mm ground clearance.
When it came to attaching the legs to the frame for the hex, we used the highly scientific method of ‘guessometry’ to determine where we needed to drill the holes required – no planning involved.
The collapsible ‘on-arm’ landing gear was designed to replace the ‘on-arm’ feet that DJI flame-wheel arms have, it’s a simple design that collapses and was not intended for use with a gimbal but it would be easy enough to make them longer, however you’ll be limited by arm length when collapsing them.
It’s worth mentioning that you don’t need to get the multi sitting exactly level on the landing gear – always ensure with any multi that the FC is level when calibrating – for operation the frame can be slightly off level when landed so long as the FC has been calibrated level. Even in Phantom or other manufactured craft, the FC may not sit completely level when the craft does. ½ degree matters then calibrating!
Step 3: Build
For the G/B quad’s landing gear I used a vice and hammer to shape the bends, having nothing else on hand. I added 5mm extra to each arm’s length to account for the two radii. Once I had the first ‘U’ bent I used it to ensure the other was identical, then drilled a series of holes wherever I could get away with it – save as much weight as you can, but don’t make them too weak.
For the collapsible landing gear I made a template out of 3mm ply then used it to duplicate the 4 aluminum ones I needed from 12x2mm bar. They were fabricated from a piece of the 12x2mm bar and hinged on a M3 bolt. The bolt runs all the way through the C-channel to increase rigidity and was secured with good ol’ nylocks. I used RC clips to secure them in the down position, and drilled holes to reduce weight.
The Hex’s undercarriage used 12x12x3mm angle for the uprights, and 19x19x1.6mm for the skids, with some leftover 25x2mm bar bracing the joints between the arms & legs, and between the legs & skids. It’d be hard to explain the design in detail so just look at the pics and replicate - or come up with your own, I’m sure there’s a better design!
Step 4: Build Another!
You’ve made your landing gear…. But…
If you’re not happy with the design you’ve made, or think that you’d like to save some weight, don’t worry! I certainly didn’t come up with these designs in an instant, and often the first attempt didn’t work out as I had envisioned, but through sketching and prototyping I managed to come up with designed that worked. I never finish tweaking and saving weight on my builds, often disassembling and reassembling every few weeks.
Pictured above is my first attempt at landing gear for the G/B quad - using pop-rivets and many separate pieces.
Have a play - I look forward to seeing what you come up with!