Flight of the Birdman (South African Popular Mechanics article)

[cpoxon 0]

From http://www.iol.co.za/index.php?click_id=116&art_id=iol1086596785309B630&set_id=1

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By Robert Fysh

At 3 000 metres, the King Air is just a silver glint in the pale sky over the Pretoria Skydiving Club, several degrees north of the GPS-designated drop zone. Just a few kilometres to go.

Inside the stripped-down interior, four "wing suiters" check their wings for the last time. Tim Mace, first out, squats in the doorway. Prop-wash and windblast batter his cheeks as he peers at the patchwork Earth below, softened by high-altitude haze. His companions bunch behind him in preparation for a quick, sequential exit.

Mace glances behind him, nods and pivots into the turbulent slipstream. His flying companions follow, just split seconds apart. They quickly stabilise, take a heading, and extend their arms.

'It's really spooky'
The wings respond instantly. Inrushing air flows through vents on the leading edge of their extended arms. The rattling zero-porosity fabric rapidly stiffens into a graceful contour as the ram-air effect completes the inflation of the tubular cells stitched into the wings of their suits. Between their extended legs, triangular wedges flare like the tail pinions of a diving hawk. The flight is strangely hushed, quite unlike the deafening roar of normal freefall.

Sensing the changed flight character-istics, Mace peels off at a 45° angle. His companions sideslip towards him in a graceful lateral manoeuvre. From the ground, the growing four-man diamond formation seems to slice across the sky; they're moving at an astonishing 150 km/h.

Two minutes later - twice the duration of a normal freefall - the wing flyers scatter for the deployment of their parafoil-shaped canopies and spiral back to the drop zone.

The wing suits, Mace explains later, retarded their fall by more than 65 percent; from 200 km/h to about 70 km/h. "It's difficult to assess actual numbers for vector speed and glide slopes," he says. "The equipment for measuring it is very expensive and would need considerable miniaturisation." But he estimates he and his companions flew horizontally at about 150 km/h and covered nearly five kilometres - the distance between their exit point and the drop zone at the Pretoria Skydiving Club.

"It's really spooky," Mace says. "If you're an experienced skydiver, you have a mind attuned to working in seconds. You get 60 seconds of work from 13 000 feet (scorning the metric system, skydivers work determinedly in feet), and you become accustomed to putting a lot of things into that one minute. So you have a very accurate one-minute brain.

"But when you wing suit, you've suddenly got to get your skydiving brain to work for two to three minutes. You get to the point where you think you're going to be there forever."

Mace has impressive skydiving credentials: he's the current overall South African champion and one of about 30 local wing suit flyers. He's also a professional test pilot for Denel Aviation, and a skydiving instructor at the Pretoria Skydiving Club. Over a 15-jump course, approved by the Parachute Association of South Africa, he teaches students to fly a straight line, turn, barrel roll, loop, spin, dive and invert.

"I look on it as a flying course… a quick introduction to gliding and aerobatics," he says, deliberately avoiding the instructional terms usually reserved for skydiving.

And so he should. Wing suiting is an advanced discipline, reserved for experienced skydivers and regulated by the Parachute Association of South Africa. Minimum requirement - 500 parachute jumps.

It's fun. It's exhilarating. Yet wing suit history reads like a battlefield casualty list. Austrian Franz Reichelt was the first to die. He "flew" a useless, wind-thrashed tablecloth contrivance from the first level of the Eiffel Tower in Paris on 4 February 1912. "If you look at photographs of him before he jumped," says Mace, "you could see that he knew he was going to die."

Attempts during the "flying circus" era of the 1920s and 1930s were considerably more successful. However, it was a perilous way to earn a living. In fact, the likelihood of witnessing a death plunge probably lured many a paying spectator; people appeared willing to pay to see a daredevil falling out of the sky, trailing the tangled remains of a canvas-draped wing and a streaming parachute.

That was exactly how the first of these "circus era" daredevils, Canadian Clem Sohn, died in 1937. At the modest altitude of 90 m, over Villacoubly near Paris, his reserve parachute "… snaked upwards and twined itself round the streaming main..."

Harry Ward, also known as "The Yorkshire Birdman", was an exception. He quit wing flying before the war and died in 2000 at 97, still a brave man. He flew large 3,4m linen "bat wings"reinforced with wooden battens.

Ward, like his barnstorming contemporaries, barely understood freefall aerodynamics. Skydivers - as today's practitioners are well aware - use their 200 km/h terminal velocity to adjust the descent rate, stabilise, and perform aerobatics.

Wrote Ward in his autobiography, The Yorkshire Birdman: "Those were the times, remember, when prolonged freefall was still feared as a potential killer and when nothing was known about the techniques of controlling the body as it hurtled through the air. (It) had to be sorted out by trial and error."

Corporal Arthur East, one of the original "loonies" in the primitive and under-funded RAF Parachute Development Unit in Northolt, England, pioneered the "trial and error sorting out" in the mid-1920s. It was East, says Ward, who "...found that the limbs could be used as control surfaces, similar to those of an aircraft in flight".

These were "trade secrets". Show jumpers did not generally share their secrets, but East, who assisted Ward in his first jump off the wing of a vibrating Vimy biplane, was a military man. He passed them on to Ward.

A former member of the French Special Air Service, Leo Valentin, nudged primitive freefall skills into a rudimentary form of skydiving after the Second World War. Skydivers credit him - erroneously, in Ward's opinion - as the first to implement the fine art of freefall aerodynamics.

"Valentin made a name for himself as a free-faller when he rediscovered the skills of body control that Arthur East had known back in the twenties," Ward writes in his book.

Valentin found - as did East - that he could stabilise himself at terminal velocity by arching his back and extending his arms and legs. He too succumbed to the lure of human flight and died "under a tangle of chutes and wings".

Comments Mace: "Skydivers today would not believe what those early birdmen did. They flew big wings - almost microlight size - stiffened by springs. They had to lie on a plank while someone tipped them out of the aircraft. It was really dangerous stuff." This brief postwar resurgence in wing flying culminated with an outright ban on winged flight by the United States Parachute Association.

Then, in the late 1980s and early 1990s, skydivers - now infinitely more knowledgeable and sophisticated - initiated a radical move away from wings supported by rigid frames. Freefall cameramen began using cloth arm-extensions to retard their descent as they filmed freefall formations. This was the era of the Jalbert parafoil, or the "square" parachute, and one of modern jumping's greatest innovators and lateral thinkers, Patrick De Gayardon, or "Deug".

Says Mace: "Deug simply made a miniature version of the flexible ram-air wing and ran it from one arm of the jumpsuit to the waist with another between the legs and a third wing under the other arm. The outstretched arms became the leading edge, creating low-pressure lift - much like an aircraft wing. It's a proper aerofoil, and it is very, very efficient. You are a genuine human glider flying right on the edge of development."

Deug died over Hawaii in 1998 - ironically, from an "avoidable human error" in the rigging of his parachute.

Is it possible to land a wing suit? "It will almost certainly happen," claims Mace, "but until somebody actually does it, it's all talk".

Today's wing suits have a 2:1 vertical descent rate and a horizontal speed of about 150 km/h. If you increase your speed just before landing and then flare out, this should reduce forward speed to about 100 km/h. It would be very similar to landing a light jet with no engine - something like a Hawk or an L39.

You'd have a very steep descent and a pull-out, levelling out for the landing. If it's ever done, it will probably happen on a very wide, very flat place with a very low friction surface - and there would still be a big impact.

"From a test pilot's perspective, if you wanted to improve performance, you would need data-gathering capabilities, miniaturised air data probes, cotton tufts and cameras that do not affect the performance of the wing. You could probably get a 10 to 15 percent improvement. But this is very hypothetical."

What would the Yorkshire Birdman think about all this? "Bloody marvellous," he would have said. "Bloody marvellous."



Visit www.humanflight.com for more information.


This article was originally published in the June issue of the South African edition of Popular Mechanics magazine.

Skydiving Fatalities - Cease not to learn 'til thou cease to live

[ltdiver 3]

Just found and read the article...went to post it and found you beat me to it!
Nice read.

Was intrigued by this paragraph:

"Comments Mace: "Skydivers today would not believe what those early birdmen did. They flew big wings - almost microlight size - stiffened by springs. They had to lie on a plank while someone tipped them out of the aircraft. It was really dangerous stuff." This brief postwar resurgence in wing flying culminated with an outright ban on winged flight by the United States Parachute Association."

So, the USPA was present back then? By that name?

ltdiver

Don't tell me the sky's the limit when there are footprints on the moon