Wingsuit flying
Wingsuit flying is the sport of skydiving using a webbing-sleeved jumpsuit called a wingsuit to add webbed area to the diver's body and generate increased lift, which allows extended air time by gliding flight rather than just free falling. The modern wingsuit, first developed in the late 1990s, uses a pair of fabric membranes stretched flat between the arms and flanks/thighs to imitate an airfoil, and often also between the legs to function as a tail and allow some aerial steering.
Like all skydiving disciplines, a wingsuit flight almost always ends by deploying a parachute, and so a wingsuit can be flown from any point that provides sufficient altitude for flight and parachute deployment – a drop aircraft, or BASE-jump exit point such as a tall cliff or mountain top. The wingsuit flier wears parachuting equipment specially designed for skydiving or BASE jumping. While the parachute flight is normal, the canopy pilot must unzip arm wings to be able to reach the steering parachute toggles and control the descent path.
Wingsuits are sometimes referred to as "birdman suits", "squirrel suits", and "bat suits".
History
An early attempt at wingsuit flying was made on 4 February 1912 by a 33-year-old tailor, Franz Reichelt, who jumped from the Eiffel Tower to test his invention of a combination of parachute and wing, which was similar to modern wingsuits. He misled the guards by saying that the experiment was going to be conducted with a dummy. He hesitated quite a long time before he jumped, and died when he hit the ground head first, opening a measurable hole in the frozen ground.A wingsuit was first used in the United States in 1930 by a 19-year-old American, Rex G Finney of Los Angeles, California. The goal was to increase horizontal movement and maneuverability during a parachute jump. These early wingsuits used materials such as canvas, wood, silk, steel, and whalebone. They were not very reliable, although some "birdmen", such as Clem Sohn and Leo Valentin, claimed to have glided for miles.
Batwings, a precursor to wingsuits, were showcased in the 1969 film, The Gypsy Moths, starring Burt Lancaster and Gene Hackman.
In the mid-1990s, the modern wingsuit was developed by Patrick de Gayardon of France, adapted from the model used by John Carta. In 1997, the Bulgarian Sammy Popov designed and built a wingsuit that had a larger wing between the legs and longer wings on the arms. He tested his prototype in a vertical wind tunnel in Las Vegas at Flyaway Las Vegas. Popov's wingsuit first flew in October 1998, but never went into commercial production. In 1998, Chuck "Da Kine" Raggs built a version that incorporated hard ribs inside the wing airfoils. Although these more rigid wings were better able to keep their shape in flight, this made the wingsuit heavier and more difficult to fly. Raggs' design also never went into commercial production. Flying together for the first time, Popov and Raggs showcased their designs side by side at the World Free-fall Convention at Quincy, Illinois, in August 1999. Both designs performed well. At the same event, jumpers performed formation wingsuit skydives with de Gayardon's, Popov's, and Raggs' suits.
Commercial era
In 1999, Jari Kuosma of Finland and of Croatia teamed up to create a wingsuit that was safe and accessible to all skydivers. Kuosma established Bird-Man International Ltd. the same year. BirdMan's "Classic", designed by Pečnik, was the first wingsuit offered to the general skydiving public. BirdMan was the first manufacturer to develop an instructor program. Created by Kuosma, the instructor program's aim was to remove the stigma that wingsuits were dangerous and to provide wingsuit beginners with a way to safely enjoy what was once considered the most dangerous feat in the skydiving world. With the help of Birdman instructors Scott Campos, Chuck Blue, and Kim Griffin, a standardized program of instruction was developed that prepared instructors. Wingsuit manufacturers Squirrel and Phoenix-Fly have also instituted coach training programs.Technique
Launch
A wingsuit pilot enters free fall wearing both a wingsuit and parachute equipment. The details of a wingsuit launch depend on whether it is a skydive from an aircraft or a BASE jump from a fixed object.Exiting an aircraft in a wingsuit requires skills that differ depending on the location and size of the door. These techniques include the orientation relative to the aircraft and the airflow while exiting. It is also important that wingsuit pilots spread their legs and arms at the proper time to avoid hitting the tail or becoming unstable. The wingsuit immediately starts to fly upon exiting the aircraft in the relative wind generated by the forward speed of the aircraft.
Exiting from a BASE jumping site, such as a cliff, requires a different technique. In these situations, a vertical drop using the forces of gravity generates the airspeed that wingsuits need to generate lift. This is also the case when exiting from a helicopter, a paraglider, or a hot air balloon. Unlike when exiting an airplane, it takes time to build up airspeed to inflate the wingsuit and provide aerodynamic control. Thus, proper orientation is critical.
File:Dubai Wingsuit Flying Trip.jpg|left|thumb|A wingsuit flyer over Palm Islands, Dubai
Glide
A wingsuit modifies the body area exposed to wind to increase the desired amount of lift and drag generated by the body. With training, wingsuit pilots can achieve sustained glide ratio of 3:1 or more. This means that for every meter dropped, three meters are gained moving forward. By adjusting the body configuration, fliers can alter both their forward speed and fall rate. The pilot manipulates these flight characteristics by changing the shape of the torso, de-arching and rolling the shoulders and moving hips and knees, and by changing the angle of attack in which the wingsuit flies in the relative wind, and by the amount of tension applied to the fabric wings of the suit. The absence of a vertical stabilizing surface results in little damping around the yaw axis, so poor flying technique can result in a spin that requires active effort on the part of the skydiver to stop.A typical skydiver's terminal velocity in belly to earth orientation ranges from 180 to 225 km/h. A wingsuit can reduce these speeds dramatically. A vertical instantaneous velocity of 40 km/h has been recorded. However, the speed at which the body advances horizontally through the air is still much higher.
The glide ratios of older wingsuits made in the 1990s through the early 2010s were closer to 2:1. It was possible for expert flyers to achieve a 3:1 ratio but this was very difficult. However, advancements in modern wingsuits allow flyers to achieve a 3:1 ratio much more easily, allowing for higher speeds.
Flare
Wingsuits can perform a flare in which airspeed is exchanged for additional lift. By first diving to build up speed, modern wingsuits can flare enough to gain altitude, but only for a short time.Deployment
At a planned altitude above the ground in which a skydiver or BASE jumper typically deploys the parachute, wingsuit fliers will also deploy their parachutes. Before deployment, pilots adjust their flight configuration by flaring to reduce their air speed. The pilot then reaches back and throws a pilot chute to initiate the parachute deployment sequence. The parachute is flown to a controlled landing at the desired landing spot using typical skydiving or BASE jumping techniques.Record-keeping
Wingsuit pilots often use tools including portable GPS receivers to record their flight path. This data can be analyzed later to evaluate flight performance in terms of fall rate, speed, and glide ratio. When jumping for the first time at a new location, BASE jumpers will often evaluate terrain using maps and laser range finders. By comparing a known terrain profile with previously recorded flight data, jumpers can objectively evaluate whether a particular jump is possible.BASE jumpers also use landmarks, along with recorded video of their flight, to determine their performance relative to previous flights and the flights of other BASE jumpers at the same site.
Suit design
Modern wingsuits use a combination of materials in order to create an airfoil shape. The main surface is typically made from ripstop nylon, with various materials used to reinforce the leading edge, and reduce drag.- The tri-wing wingsuit has three individual ram-air wings attached under the arms and between the legs.
- The mono-wing wingsuit design incorporates the whole suit into one large wing.
The air foil shape is formed by pressure inside the wing and the construction of the suit. Internal ribs help form the shape. Having a smooth leading edge is especially important as it is the source of most lift and most drag. Reducing inlet drag while maintaining high internal suit pressure is also important in modern wingsuit design. The number of air inlets and their positions vary on different suit designs. Suits that are focused on freestyle flights often have inlets on the back surface of the suit to maintain internal pressure when pilots are "back flying" in a face-up orientation.
A 2010 redesign tested in a wind tunnel by the 8th Conference of the International Sports Engineering Association found that adding material to the wingsuit between the head/helmet area and connecting it to the wrist, thus increasing upper wings' size, would "...lower lift-to-drag ratio in most testing scenarios. The decrease in lift-to-drag ratio was due to the combination of an increased lift and a higher increased drag." Other innovations in the late 2000s and early 2010s helped increase the glide ratio further.