STOL is an acronym for
Short Take-Off and Landing, used in the
aircraft industry to describe airplanes with very low
runway requirements. Most STOL aircraft are
bush planes, though some, like the
de Havilland Dash-7, are designed for use on prepared airstrips; likewise, most STOL aircraft are taildraggers, though there are some famous exceptions like the
de Havilland Twin Otter and the
Peterson 260SE.
Runway length requirement is a function of the square of the minimum flying speed (
stall speed), and most design effort is spent on reducing this number. For takeoff, large
power/weight ratios and low
drag help the plane to accelerate for flight. The landing run is minimized by strong
brakes, low landing speed or
spoilers (less common). Overall STOL performance is set by the length of runway needed to land or take off, whichever is longer.
Of equal importance to short ground run is the ability to clear obstacles, such as trees, on both take off and landing. For takeoff, large
power/weight ratios and low drag result in a high rate of climb required to clear obstacles. For landing high drag allows the airplane to descend steeply to the runway with out building excess speed resulting in a longer ground run. Drag is increased by use of
flaps (devices on the wings) and by
slipping (causing the airplane to fly somewhat sideways).
Normally, a STOL plane will have a large
wing for its weight. These wings often use aerodynamic devices like flaps,
slats, and
vortex generators. Typically, designing an airplane for excellent STOL performance reduces maximum speed, but does not reduce
payload lifting ability. The payload is critical, because many small, isolated communities rely on STOL aircraft as their only transportation link to the outside world for passengers or cargo; examples include many communities in the
Canadian north and
Alaska.
Most STOL planes can
land either on- or off-airport. Typical off-airport landing areas include snow or ice (using skis), fields or gravel riverbanks (often using special fat, low-pressure tundra
tires), and water (using
floats): these areas are often extremely short and obstructed by tall trees or hills. Wheel skis and amphibious floats combine wheels with
skis or floats, allowing the choice of landing on snow/water or a prepared runway. A STOLPORT is an airport designed with STOL operations in mind, normally having a short single runway. These are not common but can be found, for example, at
London City Airport, London, England.
List of famous STOL aircraft
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