I got into FPV (First Person Video) multi-rotor racing a few months ago. The fast, low level flying instantly reminded me of the Star Wars speeder bike Endor chase scene from Return of the Jedi. This project was an obvious choice to combine my interest and experience in RC (remote control) flight with my love of Star Wars stuff. I like always having some strange project on the work bench and this one was next in line, an attempt to build a version of the Imperial Speeder Bikes from the movie that I could “get into” and fly around myself.
The body is from a 1:6 scale (or 12 inch) Hasbro Power Of The Force series Speeder Bike (if you do a deep nerd dive on wookieepedia its a “74-Z Speeder Bike” or “Imperial Speeder Bike”.) Hasbro did a ton of re-releases of toys from the 80’s (using mostly the same molds) when they released the special edition films in ’97. The particular one I have has a 1999 stamp on it. It was re-released several times with Scout Trooper, Luke, and Leia versions. The old Hasbro toys are cool in that they are generally pretty light/hollow (plastic=$), and easy to take appart. Also while most of the shell is styrene, the skinny bits, that a kid would be most likely to break are made out of what I think is vinyl. So while it looks pretty delicate, it’s actually a pretty durable model for the weight. You can still pick them up on ebay for around $50.
The big challenge was to figure out how lift the whole thing, without making it look like just a big quad rotor tacked on. I did some layout in CAD, based off of an overhead picture of the model, and experimented with different rotor layouts that just barely cleared the rider and bike elements, kept the center of lift over the center of gravity, and was capable of lifting about 600grams. I ended up settling on a layout of four 7″ rotors, driven by 880kv 28mm motors. These motors typically spin 10″ or 11″ two-blade props on an 11.1v Lipo, so to make up for the reduction in diameter I used 3 bladed propellers, running on a 14.4v 2200mAh Lipo. It’s not the most efficient setup, but it keeps the quad compact, and lets me lift the heavier than usual frame.
The booms are 10mm carbon tubes, with stick mount style motor mounts. I angled both the autopilot and the rotors about 10 degrees forward, so that in forward flight the bike is at a level attitude.
Control is provided by a 3DRobotics PixHawk, although any controller would work, like a Naze32 or kk2 flight controller. Tuning was a bit challenging given the very short fore aft rotor spacing, but with a bit of work it flies smoothly.
The power combo could accommodate about 600g of extra mass, the bike was around 475g, so there wasn’t much left for the rider. The stock rider had a barbie doll style body, that weighed over 200g without the armor or clothing. To cut the weight down, I made a new body out of pipe cleaners and a variety of old Nerf darts (any round foam would work). A 6mm carbon tube runs through the Skeleton, and mounts into a hole drilled into the bike seat. The skeleton only weighs aroun 15g, and is much more flexible than the stock one. The boots and legs are zip tied to the bike to keep the legs from getting sucked into the rotors.
The Helmet can be swapped for an FPV camera that’s mounted to a styrofoam ball. It’s a combination camera/video transmitter unit sold by Spektrum and I’m using FatShark Dominator video goggles with a little security camera DVR to record the video on the ground.
I’ve got the Luke version on order, so I can build a second to race through the trees. I’ve also got plans for a few of the other Hasbro vehicles.
(Outdoor flight images: by Stephen Warrener)