EAA Sport Aviation - March 2011

balloon flight in 1999. Yves leapt from a platform on the side of the basket, stabilized the wing, and completed two loops.

He is now working on an even lighter wing that will bring empty weight down to 30 pounds and total weight to 100 pounds, including engines and fuel. Endurance will be increased from six to 15 minutes. “It is brand new, with a better weight distribution,” he explained. And that’s not all. JetCat is developing new, more powerful engines for Yves that the company expects will deliver 90 pounds of thrust each. Yves expects the new engines will provide a 1-to- 1 thrust-to-weight ratio, which will enable vertical climbs.

And what about independent takeoff from the ground? Yves feels it would be too tricky. As with every wing, his needs sufficient airspeed to provide lift. Even with very powerful engines, the launch from a standing start would be very unstable until the airfoil reached sufficient airspeed. One consideration is the possibility of taking off from an inclined ramp or a catapult. Yves does not rule out anything, as long as the approach is prudent and well founded in engineering. “I am not a daredevil,” he said.

GROUND-BASED LAUNCH…MAYBE? So could Yves’ wing take off from the ground one day? With his current wing and engines, he can attain launching speed from a fast-moving car. But it would take 90 seconds to reach 2,600 feet, the minimum he calculates he needs to be able to release his wing and use his parachute with enough margin in case of a mishap. However, Yves is working with the company Parachutes de France to design a parachute that will use ballistics to deploy the chute—like the emergency recovery parachutes found on ultralight aircraft. If successful, the safety altitude will be reduced to 650 feet. Taking off from a car, it would take 10 to 15 seconds to reach the safety altitude. So the level of risk would be no greater than that of a light aircraft on takeoff, Yves pointed out.

HOW JETMAN FLIES HIS WING

So how does Yves fly his wing? There are no control surfaces. No ailerons, flaps, rudder, or elevator. An early version did have small ailerons, but the later versions do not. Control is achieved through body movements. “To pitch up, I arch my back. To pitch down, I bend my body forward. To make a right turn, I tilt my head to the right. To initiate a roll, I move my shoulders,” Yves explained. He said that only small movements are needed. The secret is how the wing is installed and set on his back.

Before jumping out of the plane, helicopter, or balloon, he starts the engines and brings them to idle. He then dives (rearward, if from a helicopter or an airplane) from an altitude of about 8,000 feet and is in a free fall. At about 6,500 feet he stabilizes the wing, and as he picks up speed, he gains lift.

“As soon as the wing provides enough lift, I arch my back,” he explained. He increases the throttle of the engines and

2600 ft 0 ft 70–90 mph 650 ft BEATING THE DEADMAN’S CURVE Yves is developing a smaller and more powerful wing that would allow him to takeoff from the ground. His current wing takes 90 seconds to reach 2,600 feet, an altitude safe enough to deploy his parachute. With improved engines and a ballistic parachute system, he hopes to reduce the time to 15 seconds and the altitude to 650 feet.

flies for about 10 minutes. Engine power is controlled by a small potentiometer that clings to a finger on his right hand, so Yves’ hand retains its freedom of movement. There are almost no instruments, just an audible altimeter that speaks his altitude and has easily recognizable signals for warning altitudes that Yves sets before each flight. Cruise speed is known to be more than 130 knots.

In case one engine fails, the symmetrical engine on the other side is automatically shut down within one-tenth of a second. “Otherwise the asymmetrical engine thrust would initiate an uncontrolled roll,” Yves explained. Two of the four engines generate enough power to maintain level flight.

He flies with a combination of three parachutes: the main and reserve chute every sky diver has, as well as a third parachute incorporated into the wing itself. When the fuel runs out, he deploys his parachute and lands with the wing still attached to his back.

“In theory, I should not have been able to
fly,” he said. “But I corrected instabilities
with instinctive body movements.”
That isn’t to say he hasn’t had his share of
mishaps. In 2004 at the Al-Aïn air show in
Dubai he went into a spin, released the wing,
and tore his parachute. A year later, despite
modifications to improve aerodynamics and
stability, uncontrollable oscillations again
forced him to release the wing, which crashed
to the ground. Yves estimated he has made a
total of 250 to 300 flights with the various ver-
sions of his wing and has had to release the
wing’s harness 25 times.

Maintenance on the flying wing also involves maintaining Yves himself. “The idea is to have the ‘landing gear’ working well,” he quipped. He has no specific training program but endeavors to keep in a good shape. “Skiing is good for strength, mobility, suppleness, and reflexes,” he insisted, not shrinking from the fact that he will turn 52 this year.

At Rest

0 sec

15 sec

90 sec

SEEK FORGIVENESS, NOT PERMISSION

Another challenge in pursuing his activity involves the civil aviation authorities. For the initial, unpowered wing, the Swiss Federal Office of Civil Aviation (FOCA) was happy to greenlight Yves as long as he held both parachuting and hang-glider licenses.