Performance Flying

Performance flying is flying with the goal of maximizing wingsuit performance according to some metric. The important metrics in wingsuit flying are typically: Glide Ratio, Minimum Sink Rate, and Maximum Speed.

Maximum Glide Ratio

Glide ratio is the ratio of an aircraft's forward motion to its descent rate. It is a measure of how many feet forward for every foot of altitude down.

Glide ratio is very important in wingsuit flying, since maximum glide ratio flight defines the upper boundary of your cone of possibility — in other words, the upper limits of the airspace you could possibly fly through in a wingsuit. Any terrain flown must have a slope steeper than your maximum glide ratio, or else your glide path is guaranteed to intersect with the terrain.

In the context of wingsuit performance flying competitions, maximum glide ratio is often referred to as "maximum distance". In skydiving this is often judged using GPS logging, and measuring who covered the most distance in a particular altitude band, for example 3000m to 2000m. Since the altitude band is constant, achieving maximum distance is equivalent to achieving maximum glide.

L/D Ratio

In aerodynamics, the lift-to-drag ratio, or L/D ratio, is the amount of lift generated by an aircraft, divided by the aerodynamic drag it creates by moving through the air. When a gliding aircraft is flown at constant speed for long enough to achieve steady-state flight, glide ratio is equal to the L/D ratio. The difference between instantaneous glide ratio versus sustained glide ratio is important — it is possible to build up speed in a dive, and flare to convert forward speed into lift, and temporarily increase your glide ratio. That is different than L/D ratio which is a measure of sustained glide ratio at a particular speed.

While glide ratio and L/D ratio are related, another difference is that glide ratio is typically measured relative to the ground and can therefore be affected by wind, whereas L/D ratio depends only on airspeed not groundspeed. This must be taken into account when using technology such as GPS which measures ground speed, since it can give a misleading measure of performance in different wind conditions. For example, just because your FlySight said you were getting 3.0 : 1 glide ratio in the sky with a tail wind, don't assume you will be able to clear a ledge that requires 2.5 : 1 glide ratio on a calm day.

Minimum Sink Rate

In this flight mode, the wingsuit pilot will be descending as slowly as possible. This is also the flight mode which gives the longest possible flight time, and is also referred to as "maximum time". When flying for minimum sink rate, you will typically be flying at a slower speed and higher angle of attack. Glide ratio is typically less than the maximum glide ratio possible in a suit. In the BASE environment this can be a dangerous flight mode since low speed means very little energy stored in reserve.

To fly for minimum sink rate involves adopting a body position that creates a huge amount of drag, that gives you a slow decent rate to achieve the longest delay possible from a given altitude. Flying for maximum time sacrifices your forward speed and hence the horizontal distance you will cover. Light weight pilots have an advantage over heavier pilots when it comes to achieving minimum sink rate.[1]

Maximum Speed

Velocity can be broken down into several different components. These include: Horizontal Speed, Vertical Speed, and Total Speed. Each can be optimized independently.

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