Illumin Submission: Wingsuit Flying
Matthew Tomback
12/4/13
Bio: Matthew is a biomedical engineering undergraduate student at the
University of Southern California. He has a passion for physics and is
fascinated by humanity’s ability to overcome its natural limitations.
Keywords: Wingsuit, Flight, Parachute, Extreme, Sport
Suggested Multimedia: Flash image of wind currents moving over a
wingsuit aerofoil and the forces of lift and drag produced as a result
Abstract: Wingsuits have been developed and tested since the 1930’s,
but the modern wingsuit is a product of the last two decades. Wingsuits
rely on their aerofoil shape to generate lift and maximize the glide ratio
or proportion of distance traveled to height dropped. Design
modifications and additions such as micro jet engines are being
researched with the aim of making unassisted landing in a wingsuit and
even sustained wingsuit flight a reality.
1
Engineering Human Flight: Wingsuits
In the world of extreme sports, a wingsuit is a suit designed specifically to allow the user
to glide through the air, prolonging fall time and replicating the sensation of flight. An
experienced wingsuit pilot can manipulate his or her body to perform a variety of aerial
maneuvers, often while rocketing down a rocky mountain slope at speeds approaching 200
miles per hour. Modern wingsuits were first incepted in the late 90s, but the dream of
unpowered human flight is timeless. From legends of Icarus and his makeshift feather wings to
engineering attempts as early as the 1930s with materials ranging from silk to steel [1],
humanity has always had a fascination with the ability of flight. Modern wingsuits are equipped
with durable, webbed nylon between the arms and upper body as well as between the legs [2].
Although the technology has improved dramatically in the last decade, the strong forces and
unpredictability involved make the sport incredibly dangerous and limit the use of wingsuits to
a small niche of expert skydivers and base-jumpers willing to accept the risk. This is partly due
to the limited aerodynamic research that has been invested into optimizing the flight
capabilities of the wingsuit. Presently, wingsuit designers are more often than not wingsuit
fliers themselves. This is changing as the sport gains popularity, and more engineers are
beginning to explore the possibilities of unassisted flight as the potential for innovation in this
relatively new field grows.
An engineer developing a wingsuit must have two primary concerns: lift force and drag
force. Lift force is the upward force generated when the material composing the wings catches
the airflow as the diver plummets. It opposes the force of gravity and increases fall time. Drag
force functions similarly but in the horizontal plane, slowing the forward speed of the pilot.
2
Together these two parameters compose the glide ratio, a descriptor that defines the flight
pattern of a wingsuit. The glide ratio is the proportion of horizontal distance traveled to vertical
distance dropped as the wingsuit is flown at a constant speed. It is equivalent to the relation
between lift and drag force [3]. The glide ratio is an essential but crude measurement of a suit’s
capabilities. Pilots must maneuver through wind currents and ride ‘lifts’ of rising air, which
demands control rather than maximization of the glide ratio. The type of jump the pilot wishes
to make plays an important role in determining the optimal parameters of the wingsuit. For
long-range dives, a higher glide ratio is necessary at the expense of lift force and thus fall time.
For longer flight times, more lift force is required. This limits the glide ratio and horizontal
speed of the suit as it becomes more difficult to reduce drag force. With standard designs, the
terminal velocity of a wingsuit pilot can be lowered to around 25 miles per hour [2], a fraction
of the minimum terminal velocity a normal skydiver can reach. In this manner, wingsuits can
increase fall time for a given jump by a factor of four or more.
Maneuverability and stability under stressful conditions are also vital elements in
wingsuit design. More advanced divers will manipulate the features of the suit to slice and
curve through the air. Stunts such as dive-bombing, barrel-rolls, and flying on ones back require
a great deal of technical skill and body-control on the pilot’s part. Engineering a suit to be both
more nimble and stable can minimize the possibility of spinning out or losing one’s heading
after attempting these acrobatic maneuvers. Proximity flying – the most dangerous application
of the wingsuit – involves flying at high speeds adjacent to a slope or through small clearings or
rock formations. One experienced wingsuit pilot, Jeb Corliss, was hired to perform a stunt in
which he would fly under the arm of the iconic Christ the Redeemer statue in Rio de Janeiro,
3
Brazil. After marking his spots and a handful of practice flights, he performed 8 high-speed runs
explaining, “I knew how accurate I could be, that I could hit a six-by-six foot window easily” [2].
The daredevils that attempt proximity flight require incredibly stability in a wingsuit, as even
the smallest mistake can mean certain death.
In order to achieve the desired performance, certain aerodynamic properties of a
wingsuit may be manipulated. One important parameter is the aspect ratio, equal to the square
of the wingspan divided by the area of the wings [3]. This can be adjusted for the upper wings,
located between the arms and sides of the pilot. The lower wing – between the pilot’s legs –
has a more fixed aspect ratio limited by the range of motion and flexibility of the average pilot
(see figure 1). A greater aspect ratio in a wingsuit will catch larger volumes of air, translating
into more lift force but reduced speed and glide ratio as drag force is similarly increased by the
extra material. Varying the aspect ratio is a relatively easy method of changing the suit’s
behavior in flight.
Upper Wing Area
Lower Wing Area
Lower Wingspan
Fig 1. A modern wingsuit
(from: www.adrenalinbase.com)
4
Like most aircraft, a wingsuit relies on the concept of an aerofoil – a shape with
aerodynamic properties that produce lift. This is produced when the wing surfaces are inflated
by the force of the air as the pilot falls [1]. Engineers can manipulate an aerofoil to be more
streamlined and provide less lift or be less streamlined and provide more lift. The curvature of
the aerofoil bends the path of airstreams passing around it. The air below travels at a lower
speed, as the craft floats on top of the air currents and causes little disruption in the process.
The air above is displaced from the nose of the craft into a higher speed stream that passes
over the top of the aerofoil [4]. This high speed creates a pressure differential, with reduced air
pressure above and increased air pressure below (see Figure 2). Both changes in air pressure
contribute to the increased lifting force on the craft.
Fig 2. A diagram of a general aerofoil. Notice the displacement of air at the nose and the
pathways of the ensuing airstreams. (from: http://www.skybrary.aero/)
Other factors, such as the angle with the horizontal that the pilot assumes will affect how a
certain aerofoil responds to flight. Although a human in a wingsuit is less streamlined than the
5
wings of an aircraft, the rough aerofoil shape assumed provides enough lifting force to allow
glide ratios up to 3 [4]. Further investigation into the optimization of wingsuit aerofoils may
lead to increased glide ratios and smoother flights. See Figure 3 for a cross-section of a Vampire
wingsuit and the generic deep-chamber aerofoil formed.
Fig 3. A deep-chamber (high lift, low speed) aerofoil is visible in this cross-section of a Vampire
3 wingsuit [4]. The grey represents the elements of the suit and wings that contribute to the
aerofoil shape, which is similar to that seen in the wings of commercial jets.
How will engineers manipulate wingsuit technology over the course of the ensuing
decades? There are already a handful of groups working on the next generation of aerodynamic
wingsuits. Researchers at MIT have experimented with increasing the aspect ratio of a wingsuit
by adding a ‘forward wing’ that extends the area of the upper wings above the arms and
shoulders of the pilot. They were able to safely test the aerodynamic properties of their suit
against a standard, modern wingsuit via mannequins in a wind tunnel. The results showed an
increase in lift (by 20%) as expected as well as a surprisingly dramatic increase in drag by 60%
[3]. Their design sacrifices speed and range for increased lift and stability, effectively reducing
both horizontal and vertical velocity. With further testing and adjustments, their forward wing
6
proposal could even allow for landing without a parachute. In fact, gliding without a parachute
is a common goal for many wingsuit enthusiasts. Seen as a purer form of human flight, this may
be the most obvious direction that wingsuit technology is heading. Since the dawn of air travel,
a handful of people have fallen from the sky without parachutes and survived. In 1944 a
German Airforce gunner evacuated his flaming aircraft and fell 18,000 feet into snow and
brush. He was knocked unconscious but suffered no more than a sprained leg [2]. There are
other examples, and though uncommon, the possibility of surviving freefall without a parachute
has been proven even in unguided freefall. With respect to the wingsuit, the challenge is to
reduce landing speed to the point where a pilot can land safely without overcoming seemingly
insurmountable odds - a safe landing every time. See Figure 4 for a visual representation of
wingsuit velocity and glide ratio in comparison with other common means of flight.
7
Fig 4. This graphic shows the glide ratio and landing speeds of a variety of aircraft in comparison
with the wingsuit [5].
Increasing lift is not the only method being explored towards the goal of a reproducible,
unassisted landing. Another wingsuit designer, Maria von Egidy, is developing what she refers
to as an Integrated Glide and Landing System - a suit that can soar in for a landing with a
greater glide ratio than the 2.5 ratio of most standard wingsuits [5]. Her design adjusts the wing
shape for a more stabilized aerofoil and more importantly utilizes the concept of flaring. A flare
maneuver involves raising the nose of an aircraft when landing so that lift is maximized and
speed is minimized immediately before touch-down. Similar to a hang-glider, a pilot in her suit
8
would be able to drop out of the wings, hanging below just before landing and then running off
the remaining speed after the flare. It’s a novel idea, but the amount of weight to wing area is
still a potential hurdle. Another possibility is a jet-assisted wingsuit. Members of the American
Institute of Aeronautics and Astronautics have already made progress mapping wingsuit flight
patterns and calculating the thrust necessary for sustained, level flight [4]. Although this
technology is far from realization, the researchers have concluded that it is entirely possible.
Anyone attempting to bring this concept closer to a reality must be concerned with maintaining
the correct body position for lateral flight and limiting accidental directional changes that could
lead to dramatic altitude loss. However, the fact that engineers are investigating the possibility
is exciting in its own right, bringing humanity one step closer to the next stage of wingsuits:
sustained human flight.
As an extension of BASE-jumping, wingsuit flying is one of the most dangerous extreme
sports that one can participate in. One strong wind current and a misplaced wing can easily
send a pilot spiraling into trees, cliffs, or the ground at lethal speeds. But as technology and our
manipulation of the aerodynamic principles involved improves, engineers will begin to create
far superior, safer wingsuits than the models available today. With advances in micro-jet power,
guiding systems, and glide-ratio optimization, these harbingers of human flight will someday be
utilized for far more than a quick adrenaline rush. Sustained human flight or even
developments in reliable, precision gliding would attract both military and commercial interests
at the very least. Regardless of where it takes humanity, the dream of unassisted flight is a
powerful stimulus that will ensure that the field of wingsuit technology and application has a
bright future.
9
Bibliography
[1] R. Lamb. (2008, July 14). “How Wingsuit Flying Works.” How Stuff Works [Online]. Available:
http://adventure.howstuffworks.com.
[2] C. Hoffman (2010, Nov.). “Jump. Fly. Land.” Air & Space Smithsonian [Online]. Available:
http://www.airspacemag.com.
[3] M. Berry, J. L. Fargeas, and K. B. Blair. (2010). “Wind Tunnel Testing of a Novel Wingsuit
Design.” 8th Conference of the International Sports Engineering Association [Online]. Available:
doi:10.1016/j.proeng.2010.04.059.
[4] G. Robson and R. D’Andrea. (2010). “Longitudinal Stability Analysis of a Jet-Powered
Wingsuit.” AIAA Atmospheric Flight Mechanics Conference [Online]. Available: doi:
10.2514/6.2010-7512.
[5] J. Smith. (2009, Nov. 11). “Dangerous Dreams: Who Needs a Parachute?” New Scientist.
[Online]. Available: doi: 10.1016/S0262-4079(09)63005-0.
10