Tech

ON A bright day in 1912, an Austrian tailor named Franz Reichelt jumped off the Eiffel Tower in Paris, France. This was no suicide attempt. Reichelt was wearing a special overcoat of his own design that was supposed to let him glide gently to the ground. Sadly, it didn't work. As the crowd watched and movie cameras whirred, the "flying tailor" plunged 60 metres to his death.

Over the next few decades, up until the 1960s, daredevil showmen continued to experiment with homemade wings of canvas, wood or silk - with one crucial difference. These so-called "Birdmen" relied on parachutes to land; the wings were just there to let them "fly" on the way down. Even so, many died, usually when their wings interfered with the parachute. The idea fell out of vogue until the introduction of safer commercial wingsuits in the 1990s.

Now a small group of fearless - some would say foolhardy - wingsuit enthusiasts is reviving the dream of the very first birdmen. Their ambition is to jump out of a plane, glide thousands of metres and land in one piece - without a parachute.

At least two teams around the world are bent on tackling this pinnacle of extreme sports, and they have very different approaches in mind. In the race to be the first, secrecy rules, but the leading contenders have revealed some tantalising details of what they hope will be - only metaphorically, of course - a ground-breaking achievement.

A modern wingsuit is a full-body outfit with wings of tough nylon sewn between the arms and the torso, and between the legs: think Las Vegas-era Elvis crossed with a flying squirrel. During free fall, the airflow inflates the wings to form aerofoils, creating lift and turning a one-dimensional drop into a three-dimensional glide. While skydivers usually fall at terminal velocity - about 195 kilometres per hour - a wingsuit flier falls at only 80 to 100 km/h while travelling horizontally at 115 to 160 km/h. Skilled fliers can perform surprisingly precise aerial manoeuvres, including briefly slowing their vertical descent to zero and even gliding upwards a short distance at the end of a swooping dive. Daring individuals have skimmed as low as 5 metres above sloping ground.

Wingsuit pilots always use a parachute to touch down safely but, perhaps inevitably, a few have started to wonder if they could do without one. It's the most common thing skydivers say when they first try a wingsuit, says veteran pilot and wingsuit flier Tim Mace. "Because they're used to falling so fast, a wingsuit seems like it's stationary."

"My resentment toward the parachute surfaced early on," says Maria von Egidy, a wingsuit designer and film costume maker in Cape Town, South Africa. "There are simply too many restrictions created by its size, position and deployment."

So is a chuteless landing even theoretically possible? "It is doable," thinks physicist and parachute researcher Jean Potvin at Saint Louis University in Missouri. For it to succeed, keeping control over the flier's speed and trajectory is key. With its high speed and tiny wing area, a wingsuit is responsive to the slightest movement- more like an F-16 than a jumbo jet- and leaves little margin for error.

Copying the way others land has to be a promising approach, and is the one adopted by von Egidy, who heads a wingsuit company called Jii-Wings. Just before touchdown, parachutists and hang-gliders execute a manoeuvre called a flare: raising the craft's nose to maximise lift from its wings while cutting its speed. Larger aircraft and many birds also flare when landing. Von Egidy is developing a suit she calls the Integrated Glide and Landing System (IGALS) that will allow fliers to do the same. It aims to achieve two things, the first being a much flatter glide angle. Normal wingsuits have a glide ratio of about 2.5:1- the pilot travels 2.5 metres horizontally for every metre of fall. Von Egidy claims she can achieve 4:1 or better by increasing the suit's wingspan, stabilising the aerofoil and changing the wing's shape.

The most innovative part of the design, though, is that it allows the pilot to drop out of the wing just before landing and hang beneath it, rather like a hang-glider pilot does, making it easier to flare without losing control. This is the key to achieving the second aim: to slow "smoothly and dramatically" just before touchdown, so that the pilot ends up flying slowly enough to simply run off the excess speed, as in a parachute landing. Von Egidy, who is revealing the concept behind the suit for the first time here, claims it has "proved totally viable" in scale-model tests. She plans to enlist stunt riggers to help set up giant swings so test pilots can practise swooping. After that will come high-altitude free-fall tests, using cut-away suits that pilots can discard in mid-air if anything goes wrong.

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