Monowheel
From Wikipedia, the free encyclopedia
A monowheel is a one-wheeled vehicle similar to a unicycle. However, instead of sitting above the wheel, the rider sits either within it or next to it. The wheel is a ring, usually driven by smaller wheels pressing against its inner rim. Most are single-passenger vehicles, though multi-passenger models have been built.
Pedal-powered monowheels were built in the late 1800s; most built in the 20th century have been motorized. Some modern builders refer to these vehicles as monocycles, though that term is also sometimes used to describe motorized unicycles.
Today, monowheels are generally built and used for fun and entertainment purposes, though from the 1860s thru to the 1930s, they were proposed for use as serious transportation.
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[edit] Problems and Design Challenges
Monowheels have never caught on as a mode of transportation for several reasons.
[edit] Steering Issues
Steering systems are problematic. Proposed or attempted solutions include:
- Leaning. The most common steering solution is that the rider must lean towards his intended direction of travel to turn, and then recentralise his weight once the turn is complete.
- Turning a gyroscope to provide turning force.
- Outboard skids to provide friction drag on one side.
- Small wheels used for steering, either one to each side or a single unit either in front of or behind the vehicle. It is a matter of debate as to whether such a vehicle would still properly be called a monowheel.
- Steerable propellors, which could provide both steering and power to move the vehicle. It has been noted that having a propellor operating near pedestrians would likely be quite unsafe.
- Steerable tail surfaces, similar to those on airplanes. This solution would not work at low speeds.
[edit] Other Issues
- Limited horizontal stability. A single wheel can fall over, unless it is quite wide or has some form of active stabilization, such as a gyroscope. Some designs have used outrigger skids or small wheels to address this. In many one-person designs, being at a stop requires the driver to put their feet on the ground, the same way as on a motorcycle.
- Limited capacity. Monowheels tend to be larger than a car of similar carrying capacity. Most have been kept small by being built to carry only one rider and with little or no space for baggage.
- Risk of "gerbiling". In most designs, if the driver accelerates or brakes too hard, it is possible that the force applied overcomes the force of gravity keeping the rider at the bottom of the wheel, sending the rider spinning around the inside of the wheel. This is known as gerbiling, because it has some similarity to the situation of a gerbil running too quickly inside of a hamster wheel.
- Visibility issues. The rider is always facing the inner rim of the wheel, which can obstruct oncoming hazards.
[edit] Variants and Related Vehicles
There have been many proposals for variants or uses that were even more impractical than the basic vehicle, such as a horse-drawn monowheel or a monowheel tank. A variant was proposed that placed two riders outside of the wheel itself, with one person on each side to provide for balance.
One interesting variant presented at Burning Man in 2003 involves the passengers sitting in front of the wheel and being balanced by a heavy counterweight inside of the wheel. Rather than the typical ring drive, this vehicle is powered thru a sprocket attached to the spokes.
A related vehicle is the diwheel, in which the rider is suspended between or inside of a pair of large wheels placed side by side.
[edit] Appearances in Media
[edit] Fiction
- Iain Banks' book Against a Dark Background contains a rare instance of a monowheel as an important feature of a fictional work.
- Stanislav Lem's book 'Eden' features motorized variants.
- In the Steamboy Japanese anime movie, Ray Steam, the protagonist of the story uses a steam-powered monowheel early in the movie.
- Also, in the Gantz manga, one of the equipments provided by Gantz to the "players" (but introduced only later in the story) is a very fast kind of motorized monowheel (the Gantz Bike), used to evade the aliens in a mission.
- A monowheel was used briefly in a scene by General Grievous when battling Obi-Wan Kenobi in Star Wars Episode III: Revenge of the Sith.
- The device referred to by the title of the South Park episode The Entity is a gyroscope-stabilized, turbine-engine-propelled monowheel with a rather uncomfortable user interface.
[edit] Non-Fiction
- In an episode of the British television show Scrapheap Challenge, two teams competed to build and race monowheels.
- In the Australian Reality TV show Push the Limit a monowheel challenge ended in tears when contestant Kate Siopis fractured her wrist.
