Scientific American reports on plans for "volocopter", a human-carrying multicopter from Germany:
Inventor and physicist Thomas Senkel created an Internet sensation with the October 2011 video of his maiden—and only—test flight of a spidery proof-of-concept 16-rotor helicopter dubbed Multicopter 1. Now the maker of the experimental personal aviation craft, the European start-up e-volo, is back with a revised "volocopter" designthat adds two more rotors, a serial hybrid drive and long-term plans for going to 100 percent battery power.
The new design calls for 1.8-meter, 0.5-kilogram carbon-fiber blades, each paired with a motor. They are arrayed around a hub in two concentric circles over a boxy one- or two-person cockpit.
After awarding the volocopter concept a Lindbergh Prize for Innovation in April, Yolanka Wulff, executive director of The Charles A. and Anne Morrow Lindbergh Foundation, admitted the idea of the multi-blade chopper at first seems "nutty." Looking beyond the novel appearance, however, she says, e-volo's concept excels in safety, energy efficiency and simplicity, which were the bases of the prize.
All three attributes arrive thanks largely to evolo’s removal of classic helicopter elements. First, the energy-robbing high-mass main rotor, transmission, tail boom and tail rotor are gone. The enormous blades over a normal chopper's cabin create lift, but their mass creates a high degree of stress and wear on the craft. And the small tail rotor, perched vertically out on a boom behind the cabin, keeps the helicopter's body from spinning in the opposite direction as the main blades, but it also eats up about 30 percent of a helicopter's power.
The volocopter's multiple rotor blades individually would not create the torque that a single large rotor produces, and they offer redundancy for safety. Hypothetically, the volocopter could fly with a few as 12 functioning rotors, as long as those rotors were not all clustered together on one side, says Senkel, the aircraft's co-inventor and e-volo's lead construction engineer.
Without the iconic two-prop configuration, the craft would be lighter, making it more fuel efficient and reducing the physical complexity of delivering power to the top and rear blades from a single engine. Nor would the volocopter need an energy-hungry transmission. In fact, "there will be no mechanical connection between the gas engine and the blades," Senkel says. That means fewer points of energy loss and more redundancy for safety.
E-volo's design eliminates the dependence on a single source of power to the blades. As a serial-hybrid vehicle, the volocopter would have a gas-fueled engine, in this case an engine capable of generating 50- to 75 kilowatts, typical of ultralight aircraft. Rather than mechanically drive the rotors, the engine would generate power for electric motors as well as charge onboard lithium batteries. Should it fail, the batteries are expected to provide enough backup power so the craft could make a controlled landing.
More details and render videos at the E-Volo site.
Comments
So you are going to need a multi engine helicopter rating to fly the thing here in the US?
Very nice! So essentially, we've been prototyping the next generation of VTOL, human transport system.
I like the design, if they can pull it off. With more props, there's less probability that any single motor failure will drop the craft. With a little bit of sensor and software combination the props should be able to be reconfigured on the ply to maintain flight.
To be sure, all you need for an ultralight multirotor is a 75KW generator. Problem solved.
Kohler 60 KW RES LP Gas Residential Standby Generator
The beauty of a heli is it does not throw its prop into anything on board when it fails. I think if a prop fails on this beast it could be bad for the pilot or other props. On the plus side 1/18 rotors failing is probably better than 1/1 rotor failing.
i only need 8 motors
I want something electric that straps on your back like this guy.
I don't see how this is any more (or less) maintenance intensive than a typical helicopter. You've gotten rid of an oil system, an actuation system, and the transmission itself, but have replaced it with a multitude of identical but very simple components that are electrically operated (which is nice).
That said, I doubt it will be as weight efficient as a standard helicopter (in lbs thrust/hp), given that there are gaps in rotor 'disc'. You've replaced the blades with a large supporting structure that doesn't really do anything. Additionally, going from fuel->mechanical generator->speed controller->motor probably has equivalent losses if not more than a standard mechanical transmission. The real gain is the removal of the tail rotor, but a coax or a tandem rotor has the same advantage. It's interesting, but it faces serious limitations due to current battery technology (in terms of capacity vs weight). The redundancy aspect is neat, but the 'hypothetical' tag makes me wonder, and you can always autorotate in a standard helicopter.
I don't see this as a breakthrough, but only an example of what current technology can give us for an electric helicopter. I would expect as motor, battery, and generator technology advance that electric designs would converge on typical helicopter designs.
Maintenance nightmare.
I have serious doubt about the efficiency of multiblade. It will need to carry heavy battery, heavy generator, heavy gaz engine, the multirotor structure instead of one heavy gaz engine/transmission. But, two supraconductor electric engine (counter rotor) could be more interresting ....
This is what I'm taking about!