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Take four skydivers, two hot air balloons, a 125m long rope with a seat on the end, climb to 1,800m and this is what you get – Mega Swing, the result of an idea to make the world's longest swing.
"You have this acceleration in another direction, unlike anything you'd experience with a normal BASE jump or skydive," says Roithmair, who came up withe the idea. "You jump, freefall, waiting for the moment when the line goes tight, then suddenly there's this non-motorised acceleration. I cann't think of a freefall that had such different patterns of movement."
Watch the world's biggest swing.
The idea behind Mega Swing was to realise that childhood dream we all have, says Lettner. "It's the dream of everyone," he says. "To swing higher and higher, and finally jump off and fly."
"We were initially all a little skeptical about whether it wouldl work at all," adds Waltenspiel. "But it was just perfect in the end."
The most unique part of the stunt was the lack of noise. "If you're in an airplane or helicopter, you always have that noise around you. Here you only hear from the burner," said Roithmair. "Even the rocking is very special. You hear only the wind at the end of the pendulum, it's actually very quiet."
To pull off the stunt was a major logistical challenge. The team required not just perfect weather, but expert hot air balloon pilots. The two balloons had to be exactly at the right distance apart to have the perfect tension in the swing before making the jump.
As for the hardest part? "Staying on board the swing," says Roithmair.