A skilled mountain biker can cross some extreme terrain, but [The Q] thought there might be room for improvement, so he converted a fat bike to all-wheel drive.
The major challenge here is transferring pedal power to the front wheels, especially around the headset. [The Q] solved this by effectively building a differential from the parts of a very old hand drill. Since the front wheel needs to rotate at the same speed as the rear, one long chain loops from the rear wheel to the headset, tensioned by a pair of derailleurs. This front sprocket turns a series of spur gears and bevel gear arranged around the headset, which transfers the power down to the front wheel via another chain.
It would be interesting to feel what the bike rides like in soft sand, mud, and over rocks. We can see it has some advantages in those conditions but were unsure if it would be enough to offset the penalty in weight and complexity. The additional chains and gears certainly look like they’re asking to catch foliage, clothing, and maybe even skin. However, we suspect [The Q] was more likely doing it for the challenge of the build, which we can certainly appreciate. With the rise of e-bikes, adding a hub motor to the front wheel seems like a simpler option.
We’ve seen several interesting bicycle hacks over the years, including a strandbeest rear end, 3D printed tires and an automatic shifter. Continue reading “All-Wheel Drive Bicycle Using Hand Drill Parts”
Question: Can a flywheel store enough energy to power an airplane? Answer: Yes it can, for certain values of “flywheel” and “airplane.”
About the only person we can think of who would even attempt to build a flywheel-powered airplane is [Tom Stanton]. He’s a great one for off-the-wall ideas that often pay off, like his Coandă effect hovercraft, as well as for ideas that never got far off the ground, or suddenly met it again. For most of the video below, it seems like his flywheel-powered plane is destined to stay firmly in the last category, and indeed, the idea of a massive flywheel taking flight seems counterintuitive. But [Tom] reminds us that since the kinetic energy stored by a flywheel increases as the square of angular velocity, how fast it’s turning is more important than how massive it is. The composite carbon fiber and aluminum flywheel is geared to the propeller of a minimal airplane through 3D-printed bevel gears, and is spun up with an external BLDC motor.
Sadly, the plane never made it very far, no matter how much weight was trimmed. But [Tom] was able to snatch victory from the jaws of defeat by making the propeller the flywheel – he printed a ring connecting the blades of the prop and devised a freewheel clutch to couple it to the motor. The flywheel prop stored enough energy to complete a few respectable flights, as well as suffer a few satisfyingly spectacular disintegrations.
As always, hats off to [Tom] for not being bashful about sharing his failures so we can all learn, and for the persistence to make his ideas take flight.
Continue reading “Flywheel Stores Energy To Power An Airplane – Eventually”