Skydiving Without a Parachute
Jump out of an aircraft without a parachute - are you mad? Probably. What if you could have a reserve parachute and wear a wingsuit? OK, keep talking...
For some the idea of jumping out of an aircraft in a wingsuit and landing without a parachute is approaching reality. The New York Times recently ran a story Flying Humans, Hoping to Land with no Chute, which profiled extreme skydiver and BASE jumper, Jeb Corliss. His quest is to be the first human to land, aided only by a wingsuit, after jumping from a helicopter.
A wingsuit (also known as a birdman suit or a squirrel suit) is a skydiving suit with fabric extensions sewn between the legs, and between the arms and torso. During freefall the fabric extensions act as primitive wings, providing lift to slow the vertical rate of descent and increase horizontal speed.
The essence of gliding (flying without thrust) is to counter gravity with lift and drag forces. A wingsuit is no exception to this rule. The glide angle (is the angle between the glider and the horizontal) is proportional to the ratio of drag divided by lift and is a measure of aerodynamic efficiency. The higher the lift and lower the drag, the more efficient the design. A wingsuit is not a particularly efficient aerodynamic device given the limited area to form wings and our bulky bodies, so you can expect a relatively steep glide angle. In other words, both the vertical and horizontal speeds during landing will be hazardous to human health.
For a safe landing the aim is to minimize both vertical and horizontal speeds. This rule applies across the full spectrum of flyers from insects to the Space Shuttle, and most definitely to a human wearing a flimsy wingsuit. Using a state-of-the-art wingsuit a skydiver will still be moving 30 mph vertically and 75 mph horizontally - not conducive speeds for injury-free landings. Clearly, a means to land safely requires a reduction in speed relative to the landing surface for the skydiver to tell the tale after the event. Options to consider are:
- Airbrake or aerodynamic spoiler - as found on airplanes
- Tail parachute - though this could be considered a cheat
- Frictionless slope - such as a ski jump covered in ice
- Moving platform to reduce the horizontal speed difference with the ground - such as the flight deck on an aircraft carrier
- Airbags - proved successful for the Mars rover landings...
Whatever landing solution Corliss and his fellow thrill seekers are planning, they aren't saying. Seems like an ideal scenario to perform simulations - lots of simulations - before committing to the real thing
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