Archive for March 21st, 2012

21
Mar
12

birdman soars with human-powered wings

Post from Alan Brown:

Dutch mechanical engineer Jarno Smeets has broken new ground by flying like a bird—not inside a vehicle, of course, but with flapping wings attached to a power pack on his body.

Yes, this is for real. Smeets accomplished the feat this past Sunday in a park in The Hague (view the video).

Smeets soared 10 to 15 meters above the ground for about 60 seconds. That is roughly five times longer than the Wright Brothers’ first flight at Kitty Hawk 99 years ago (and about as long as their concluding flight that first day).

This is not the first ornithopter, a vehicle that flies by flapping its wings like a bird. The first human-powered one I can find dates back to 1929, though some question whether it flew or was actually towed by a car on the ground. More recently, in August 2010, a team at the University of Toronto Institute for Aerospace Studies flew 145 meters, though it was also towed until it took off. Smeets’ flight differed in two ways: First, he took off by running; second, it was not human-powered flight.

Smeets calculated that his arms could provide less than 10 percent of the continuous power needed to lift his 180 pound body into the sky. This meant he needed to build a power system.

What he came up with—scavenged from Wii game systems and Android smartphones—would delight any garage mechanic.

Let’s start with the wings. They consist of 185 square feet of lightweight fabric stretched taut over carbon-reinforced windsurfing masts. Each wing weighs just 37 ounces and has a hinge about halfway down its length.

The power pack weighs 40 pounds. It starts with four 5,000 mAh batteries, which power two Turnigy motors. The motors have 1:25 planetary gearboxes, and eccentric shafts that connect to the wing mast and produce up-and-forward thrust.

So how does he fly? The secret lies in some scavenged electronics. This starts with two Wii accelerometers, one on the wing and the other in the back. The first measures the acceleration of his arm, the second the acceleration of the wing.

An Android phone processor calculates the difference between the two in order to determine motor output. There is also a Wii gyroscope to measure pitch, yaw, and roll. The data is used to help stabilize the system.

The system enables Smeets to move his arms freely without any risk of breaking them. The wings mimic an albatross.

“Ever since I was a little boy I have been inspired by pioneers like Otto Lilienthal, Leonardo da Vinci and also my own grandfather,” Smeets said.

What happens next? Smeets says this is an open source technology, and credits the bird flight community with many useful suggestions. He plans to share his bird wing concept with others through his blogs and YouTube channel.

It is an amazing story and I certainly want to learn more. I imagine what it would feel like to soar over the ground, even for 60 seconds. It gives me the chills. Isn’t that what great engineering should do?

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The Editor

John G. Falcioni is Editor-in-Chief of Mechanical Engineering magazine, the flagship publication of the American Society of Mechanical Engineers.

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