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Black Fury

December 19th, 2021 Leave a comment Go to comments

A simple vehicle built for attempting a speed record with a pure LEGO build. Only managed 21 km/h, which was disappointing.


Completion date: 19/12/2021
Power: electric (LEGO RC unit)
Remote control: radio (LEGO RC unit)
Dimensions: length 58 studs / width 25 studs / height 17 studs (not including antenna)
Weight: 0.954 kg (0.649 kg without batteries and camera)
Suspension: front – double wishbone independent with positive caster angle, rear – none
Propulsion: 2 x LEGO RC buggy motor, directly
Motors: 2 x LEGO RC buggy motor

This vehicle was a follow-up on my 2014’s Torpedo Trike which managed just over 20 km/h using LEGO parts only. I wanted to improve that result, thinking that I could use the new big wheel from the LEGO 42130 set to achieve higher speed and NiZn batteries to handle extra stress that a bigger wheel would put on the motors.

Just like previously, the vehicle was built like an inverted trike, with two front wheels ensuring stability and providing steering and a single rear driving wheel eliminating the need for a differential and keeping the drivetrain as simple as possible (literally a single LEGO axle). Compared to the Torpedo Trike, the new vehicle was lower, longer and wider, because I had too much experience with LEGO pieces being ground away by tarmac at high speeds. In other words, it was built to be as stable as possible, as light as possible, and with the RC unit and the camera being reasonably protected from damage. I also kept the front suspension very soft to minimize vibrations which get quite serious at large speeds, and instead of adding a front bumper, I’ve decided to build the front axle so that in the event of a head-on collision, the front wheels could easily come off and the whole front axle could disconnect from the chassis, hopefully dissipating some energy from the impact. This, in fact, was what kept happened during collisions, except that the very first collision clipped one of 4 pins keeping the front axle attached to 3/4 of the original length, and after the next collision another pin was gone completely.

The bike only managed a little under 22 km/h and this was a huge letdown. The RC motors seemed to be working at their maximum capacity, in fact they would trip the RC unit’s current breaker whenever I’ve tried do start driving at full speed, so I had to take advantage of LEGO RC remote’s adjustable speed and start slow, then gradually build the speed. I had to wonder whether the RC unit isn’t handling the NiZn batteries too well, or whether the significant mileage of my LEGO RC buggy motors is starting to show.


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