Ashort takeoff and landing (STOL)aircraft is afixed-wing aircraft that can takeoff/land on shortrunways. Many STOL-designed aircraft can operate onairstrips with harsh conditions (such ashigh altitude or ice). STOL aircraft, including those used in scheduled passenger airline operations, can be operated fromSTOLport airfields that feature short runways.
For any plane, the requiredrunway length is a function of the square of thestall speed (minimum flying speed), and much design effort is spent on minimizing this number. Fortakeoff, largepower/weight ratios and lowdrag help the plane to accelerate for flight. For landing, the length is minimized by strongbrakes, low landing speed, andthrust reversers orspoilers. Overall STOL performance is set by the longer of the runway needed to land or take off.[2]
Of equal importance to runway length is the ability to clear obstacles, such as hills, beyond the runway. For takeoff, largepower/weight ratios and low drag increase the rate of climb – required to clear obstacles. For landing, high drag allows the plane to descend steeply without building speed, which would require a longer ground run. Drag is increased by use offlaps on the wings and byforward slip (causing the plane to fly somewhat sideways to increase drag).[3]
Typically, a STOL aircraft has a largewing for its weight. These wings may useaerodynamic devices like flaps,slots,slats, andvortex generators.[4] Typically, achieving excellent STOL performance reduces maximum speed, but notpayload ability. The payload is critical, because many small, isolated communities rely on STOL aircraft as their only link to the outside world for passengers or cargo; examples include many communities in theCanadian north andAlaska.[5][6][7]
Most STOL aircraft canland 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-pressuretundra tires), and water (usingfloats): these areas are often short and obstructed by trees or hills. Wheel skis and amphibious floats combine wheels withskis or floats, allowing landing on snow/water.[citation needed]
Horton, Inc, ofWellington, Kansas, offers STOL kits under the brand nameHorton STOL-Craft, emphasizing that the modifications increase safety by allowing forced landings to occur at lower speeds and thus improve survivability. The Horton modifications include a droopedleading edge cuff, conical camberedwingtips, control surface gap seals andwing fences. The company says: "On an average you can expect to get a 4-7 knot reduction in stall speeds. Flying at these lower stall speeds you can reduce the take-off and landing distances by 10%". Horton STOL kits are available for severalCessna andPiper PA-28 models.[9][10][11]
Micro AeroDynamics marketsvortex generator modification kits for "STOL benefits". The Micro kits are small vortex generators that are glued to the wing leading edge, as well as the underside of theelevator and on the fin. Kits are available for a large number of light aircraft types.[12]
Sierra Industries sells Robertson STOL kits, marketed under the name R/STOL, incorporate a drooped leading edge cuff, wing fences, drooping ailerons and an automatic trim system. The company says that installation "allows 15 to 25 MPH slower approaches and requires up to 40% less runway distance". R/STOL kits are available for various Cessna models.[13][14][15]
Stolairus Aviation of Kelowna, British Columbia, has developed STOL Kits for thede Havilland Canada DHC-2 Beaver andde Havilland Canada DHC-3 Otter to increase lift and reduce stall speeds. The DHC-2 Beaver STOL Kit includes a contoured leading edge, flap-gap seals, wing fences and drooped wingtips. The DHC-3 Otter STOL Kit includes a contoured leading edge and drooped wingtips.[16]
ASTOLport or STOLPORT was an airport designed with STOL (Short Take-Off and Landing) operations in mind, usually for an aircraft class of a certain weight and size. The term "STOLport" did not appear to be in common usage as of 2008, although was commonly used by pilots flying intoBiggin Hill during 1986/87 when theLondon City Airport was opened restricting approaches and ceilings to the north of Biggin. A STOLport usually has a short single runway, generally shorter than 1,500 m (5,000 ft).[17] STOLports are only practicable by certain types of aircraft, especially smaller propeller aircraft, with performances that are compatible with the shorter runway length, steeper approach/departure paths, etc. at individual STOLports. In the United States, short runway facilities are simply known as airports, and the term "STOLport" has not been commonly used since the early 1970s.
Many definitions of STOL have been used over time and for regulatory and military purposes.[20] These include:
(DOD/NATO) The ability of an aircraft to clear a 50-foot (15 meters) obstacle within 1,500 feet (450 meters) of commencing takeoff or in landing, to stop within 1,500 feet (450 meters) after passing over a 50-foot (15 meters) obstacle.
— Department of Defense Dictionary of Military and Associated Terms (JP 1-02)[21]
the ability of aircraft to take off and clear a 50-foot obstruction in a distance of 1,500 feet from beginning the takeoff run. It must also be able to stop within 1,500 feet after crossing a 50-foot obstacle on landing.
An aircraft that, at some weight within its approved operating weight, is capable of operating from a STOL runway in compliance with the applicable STOL characteristics and airworthiness, operations, noise, and pollution standards" and ""aircraft" means any machine capable of deriving support in the atmosphere
an aircraft with a certified performance capability to execute approaches along a glideslope of 6 degrees or steeper and to execute missed approaches at a climb gradient sufficient to clear a 15:1 missed approach surface at sea level... A STOL runway is one which is specifically designated and marked for STOL aircraft operations, and designed and maintained to specified standards.
Heavier-than-air craft that cannot take off and land vertically, but can operate within areas substantially more confined than those normally required by aircraft of the same size. Derived from short takeoff and landing aircraft.
— McGraw-Hill Dictionary of Scientific & Technical Terms[27]
heavier-than-air craft, capable of rising from and descending to the ground with only a short length of runway, but incapable of doing so vertically. The precise definition of an STOL aircraft has not been universally agreed upon. However, it has been tentatively defined as an aircraft that upon taking off needs only 1,000 ft (305 m) of runway to clear a 50-ft (15-m) obstacle at the end of that distance and upon landing can clear the same obstacle and then land within 1,000 ft.
The STOL mode of flight is one during which an airplane taking off or landing is operated at climb-out and approach speeds lower than the conventionally accepted margins of airspeed above the power-off stalling speed of the airplane.
— Lieutenant Colonel Walter P. Maiersperger, USAF (Ret)[28]
Some manufacturers market their products as STOL without specifying that the aircraft meets an accepted functional definition.[29]
Rough-field capability is the ability to land/take-off from an unprepared/damaged runway or grass field, highway, wasteland or other ad hoc site. Rough-field capable aircraft usually have high wings, reinforced landing gear, and STOL capability.[30][31][32][33][34][35][36][37][excessive citations]
^Mallela, J.; Wheeler, P.; Le Bris, G.; Nguyen, L.-G. (2023). ACRP Research Report 243: Urban Air Mobility: An Airport Perspective. Transportation Research Board, Washington, DC:Urban Air Mobility: An Airport Perspective
^McGraw-Hill Dictionary of Scientific & Technical Terms (2003)."STOL aircraft". Retrieved2009-12-25.
^Maiersperger, Walter P., Lieutenant Colonel, USAF (Ret) (March–April 1968)."What is STOL?". Archived fromthe original on 2011-07-22. Retrieved2009-12-25.{{cite web}}: CS1 maint: multiple names: authors list (link)
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STOL Ultralight taking off and landing
The dictionary definition ofSTOL at Wiktionary