One well-known backyard inventor has proven common sense and engineering experience aren't prerequisites for creating crazy multicopters. By strapping a couple of two-stroke parajet motors and propellors to a metal frame, Colin Furze has built a DIY hoverbike that may not give Franky Zapata any sleepless nights, but looks like a sketchy alternative to creations like the Malloy Hoverbike or Aero-X.
The initial design of the craft had two motors and propellors mounted to the bottom of the frame and turning in the same direction, but Furze switched to an S-shaped metal frame that allowed each propellor to rotate in opposite directions. This design, which Furze compares to a Chinook's twin-rotor setup, was implemented because the counter rotation of the propellors cuts down on gyroscopic spin.
The final creation is able to lift its creator off the ground, albeit with little in the way of directional control or stability. As the team behind Yeair! discovered, two-stroke gasoline engines provide plenty of power but lack the lightning-quick response required to make the split-second adjustments required to maintain stable flight.
Whereas Yeair's design used an electric motor to provide instant torque to compensate, Furze's homegrown creation is far more low-tech and relies on its brave (or foolish) inventor's wrangling, and control of each individual throttle, to stay in the air. It makes for dramatic video, but also leads to a few crashes.
According to Furze, there was talk of adding a stabilization system, but the engines were already struggling to get him off the ground, and any more hardware would've simply been too heavy.
The project was funded by Ford who will be glad no-one was hurt during filming, but we'd still keep this firmly in the "don't try this at home" column.
A video of the bike's first flight is below, and the full development process has been mapped on Furze's YouTube channel.
Source: Colin Furze
You have little stability because the CoG of the machine + pilot is far too high.
With a flex-wing microlight-type connection between pilot's weight and the rest of the machine you would be very stable and be able to control direction by simply moving the machine (and therefore its thrust) about the weight of the pilot.
Why not (more) fully cage the props to stop them hitting stuff (including you!)?
Have you done the calcs to see if you have properly matched props to motor/gearbox? Just bigger props may give more lift. Otherwise you just need more efficient motors - smaller & lighter per power output. Your existing setup runs out of puff beyond the advantage given by 'ground effect'... https://en.wikipedia.org/wiki/Ground_effect_(aerodynamics)
Please don't kill yourself - some basic motorcycle-type clothing (esp a helmet with eye protection) would be a distinct advantage - I'm sure your Mum would agree.
- Cici