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Although reassuring, the point on the Dart Flyer website might seem self-explanatory. Perhaps when you are dealing with engineering this weird, however, a little clarification doesn’t hurt.
Proposed by designers at Ray Research for a Boeing-sponsored competition, the Dart Flyer is described as a “single-person tail-sitter vertical take-off and landing aircraft”. A pilot would slide into the thin tube on top of the four large rotors. After reaching sufficient height, the craft would turn horizontal and use its two larger delta wings for unspecified “fast” cruise flight.
The GoFly competition calls for “safe, quiet, ultra-compact” entries capable of flying 20 miles without refuelling. “Together, we will make people fly,” says the competition website. But would the Dart Flyer make them do anything else?
“I’ve ridden a motorbike down the German autobahn at 130mph, and I’ve scaled a vertical rock face 200ft up without a rope, but that looks a bit scary,” says Steve Wright, associate professor of aerospace engineering at the University of the West of England. ”What happens if it lands the wrong way up?”
‘Fail-safe’ propulsion
Ray Research’s website promises “patent-pending fail-safe electric propulsion, without any single point of failure”. Each of the four motors would be capable of providing at least 75% of the power needed to prevent crashes, say the designers.
The rudder could potentially compensate for an unbalanced aircraft after a motor failure, says Wright, but he also raises a bigger issue. The Dart Flyer is a scaled-up version of a much smaller unmanned drone, but the laws of physics could prevent a full-sized 2m x 2.4m version from working. “Everything changes when you scale up like that,” says Wright. While the size of the manned concept is in equal proportion to the unmanned version, other parameters would change at different rates – energy demand, for example.
“You need a lot of batteries,” says Wright. “They get very hot and you have to start cooling them.” Although that cooling would be welcome for any sweating pilot, it would add a lot of mass. “Unfortunately you can’t argue with the laws of physics.”
An autopilot to compensate for changes in balance – and potentially to land the aircraft as well – would be a comparatively small issue, says Wright.
The Dart Flyer was not one of the 10 winners of GoFly’s phase-one contest, so Ray Research won’t get a share of $2m and the bizarre concept may never fly.
One criterion for the competition, however, was that the invention should “provide the thrill of flight”. The Dart Flyer would certainly have done that.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.