Point take off and landing (PTOL) is an evolving term describing special take-off and landing capabilities of

unmanned aerial vehicle An unmanned aerial vehicle (UAV) or unmanned aircraft system (UAS), commonly known as a drone, is an aircraft with no human pilot, crew, or passengers onboard, but rather is controlled remotely or is autonomous.De Gruyter Handbook of Dron ...

s (UAVs),

tail-sitter A tail-sitter, or tailsitter, is a type of VTOL aircraft that takes off and lands on its empennage, tail, then tilts horizontally for forward flight. Originating in the 1920s with the inventor Nikola Tesla, the first aircraft to adopt a tail-sit ...

and other aircraft. PTOL indicates that there is no requirement for a

runway In aviation, a runway is an elongated, rectangular surface designed for the landing and takeoff of an aircraft. Runways may be a human-made surface (often asphalt concrete, asphalt, concrete, or a mixture of both) or a natural surface (sod, ...

for operations (i.e.,

point-defence Point defence (or point defense; see spelling differences) is the defence of a single object or a limited area, e.g. a ship, building or an airfield, now usually against air attacks and guided missiles. Point defence weapons have a smaller range in ...

). Instead, 'point' suggests that the length of runway required is near zero, implying a minimal-sized location for touchdown and takeoff. Sometimes no prepared surface at all is needed. PTOL is assisted in certain cases by means which are not needed by

vertical take-off and landing A vertical take-off and landing (VTOL) aircraft is one that can take off and land vertically without relying on a runway. This classification can include a variety of types of aircraft including helicopters as well as thrust-vectoring fixed-wing ...

(VTOL) or by short take-off and landing (STOL) vehicles. These may include a very long cable enforcing the convergence of the aircraft from afar onto the intended touchdown point. This may still be worthwhile due to maintaining the air-vehicle's advantages which are maximal simplicity leading to better cruise performance, as is the case using a fixed-wing UAV platform.

Advantages

PTOL capability enables UAVs and aircraft to land and take off in very confined locations like rooftops, ship decks and forest clearings. This is comparable to VTOL, but it helps fixed-wing/simple UAVs achieve this, avoiding the complexity and cost of air-vehicle construction required for VTOL which include jet-thrust-rotation engines, engine pods or rotor tilting mechanisms. This gives higher

aerodynamic Aerodynamics () is the study of the motion of atmosphere of Earth, air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dynamics and its subfield of gas dynamics, and is an ...

efficiency and allows smaller engines and lower cost, among other advantages. Also, a true PTOL solution means exact touchdowns even in adverse conditions such as the rolling and heaving deck of a ship, strong winds on land, or nearby obstacles such as trees or rocks. The ability to land a UAV direct onto a vehicle, with cushioning, adds safety to deployed UAVs, providing touchdown with no-runway or pre-prepared area and easing a quick change of the landing-site. The fact that PTOL capable UAVs can land unassisted on rolling ships gives them an advantage over manned helicopters.

Implementation

PTOL takeoffs are quite simple. Any rocket launched from a tube, or an UAV launched by a rail-launcher or similar means, is in effect making a point takeoff. For the landings, several ideas have been proposed. An example for sea operations is catching a UAV in a parachute in the air behind a ship, then lowering the UAV to the deck by pulling the parachute in. Another idea is 'cable-assisted PTOL' for fixed-wing UAVs. The UAV makes a cable connection to a surface

winch A winch is a mechanical device that is used to pull in (wind up) or let out (wind out) or otherwise adjust the tension (physics), tension of a rope or wire rope (also called "cable" or "wire cable"). In its simplest form, it consists of a Bobb ...

(on a ship or on the ground) and the winch pulls the UAV down to the intended 'point'. This is potentially useful for land and naval usage of fixed-wing UAVs.

Patents

Patent 4,790,497 "Point-landing method for non vertical take off and landing flying objects" Patent 4,753,400 "Shipboard air vehicle retrieval apparatus" Patent 4,311,290 "Arrestment system"

References

{{DEFAULTSORT:Ptol Types of take-off and landing

Advantages

Implementation

Patents

See also

References