PTOL

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Point take off and landing (PTOL) is an evolving term describing special take-off and landing capabilities of unmanned aerial vehicles (UAVs) and other aircraft.

Unmanned aerial vehicle Aircraft without a human pilot aboard

An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without a human pilot onboard. UAVs are a component of an unmanned aircraft system (UAS); which include a UAV, a ground-based controller, and a system of communications between the two. The flight of UAVs may operate with various degrees of autonomy: either under remote control by a human operator or autonomously by onboard computers.

Contents

PTOL indicates that there is no requirement for a runway for operations. 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.[ citation needed ]

Runway Area of surface used by aircraft to takeoff from and land on

According to the International Civil Aviation Organization (ICAO), a runway is a "defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft". Runways may be a man-made surface or a natural surface.

PTOL is assisted in certain cases by means which are not needed by vertical take-off and landing (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. [1] 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.

VTOL aircraft takeoff and landing done vertically without need of any form of runway

A vertical take-off and landing (VTOL) aircraft is one that can hover, take off, and land vertically. This classification can include a variety of types of aircraft including fixed-wing aircraft as well as helicopters and other aircraft with powered rotors, such as cyclogyros/cyclocopters and tiltrotors. Some VTOL aircraft can operate in other modes as well, such as CTOL, STOL, and/or STOVL. Others, such as some helicopters, can only operate by VTOL, due to the aircraft lacking landing gear that can handle horizontal motion. VTOL is a subset of V/STOL. Some lighter-than-air aircraft also qualify as VTOL aircraft, as they can hover, takeoff, and land with vertical approach/departure profiles.

STOL A class of airplanes that are designed to takeoff and land in a short distance

STOL is an acronym for a short takeoff and landing aircraft, which have short runway requirements for takeoff and landing. Many STOL-designed aircraft also feature various arrangements for use on runways with harsh conditions. STOL aircraft, including those used in scheduled passenger airline operations, have also been operated from STOLport airfields which feature short runways.

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.

Aircraft engine Engine designed for use in powered aircraft

An aircraft engine is a component of the propulsion system for an aircraft that generates mechanical power. Aircraft engines are almost always either lightweight piston engines or gas turbines, except for small multicopter UAVs which are almost always electric aircraft.

Nacelle

A nacelle is a housing, separate from the fuselage, that holds engines, fuel, or equipment on an aircraft. In some cases—for instance in the typical "Farman" type "pusher" aircraft, or the World War II-era P-38 Lightning—an aircraft's cockpit may also be housed in a nacelle, which essentially fills the function of a conventional fuselage. The covering is typically aerodynamically shaped.

This gives higher aerodynamic 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.

Aerodynamics branch of dynamics concerned with studying the motion of air

Aerodynamics, from Greek ἀήρ aer (air) + δυναμική (dynamics), is the study of motion of air, particularly as interaction with a solid object, such as an airplane wing. It is a sub-field of fluid dynamics and gas dynamics, and many aspects of aerodynamics theory are common to these fields. The term aerodynamics is often used synonymously with gas dynamics, the difference being that "gas dynamics" applies to the study of the motion of all gases, and is not limited to air. The formal study of aerodynamics began in the modern sense in the eighteenth century, although observations of fundamental concepts such as aerodynamic drag were recorded much earlier. Most of the early efforts in aerodynamics were directed toward achieving heavier-than-air flight, which was first demonstrated by Otto Lilienthal in 1891. Since then, the use of aerodynamics through mathematical analysis, empirical approximations, wind tunnel experimentation, and computer simulations has formed a rational basis for the development of heavier-than-air flight and a number of other technologies. Recent work in aerodynamics has focused on issues related to compressible flow, turbulence, and boundary layers and has become increasingly computational in nature.

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 (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.

Winch device used to pull in or let out a rope or cable

A winch is a mechanical device that is used to pull in or let out or otherwise adjust the tension of a rope or wire rope. In its simplest form, it consists of a spool attached to a hand crank. Winches are the basis of such machines as tow trucks, steam shovels and elevators. More complex designs have gear assemblies and can be powered by electric, hydraulic, pneumatic or internal combustion drives. It might include a solenoid brake and/or a mechanical brake or ratchet and pawl which prevents it unwinding unless the pawl is retracted.

Patents

Patent 4,790,497 "Point-landing method for non vertical take off and landing flying objects" [2]

Patent 4,753,400 "Shipboard air vehicle retrieval apparatus" [3]

Patent 4,311,290 "Arrestment system" [4]

Related Research Articles

STOVL Aircraft takeoff and landing class capable of taking off from a short runway and landing vertically without a runway

A short take-off and vertical landing aircraft is a fixed-wing aircraft that is able to take off from a short runway and land vertically. The formal NATO definition is:

A Short Take-Off and Vertical Landing aircraft is a fixed-wing aircraft capable of clearing a 15 m obstacle within 450 m of commencing take-off run, and capable of landing vertically.

Takeoff transition from being on a surface to being in flight

Takeoff is the phase of flight in which an aerospace vehicle goes from the ground to flying in the air.

V/STOL Aircraft takeoff and landing using either a short runway or vertically

A vertical and/or short take-off and landing (V/STOL) aircraft is an airplane able to take-off or land vertically or on short runways. Vertical takeoff and landing (VTOL) aircraft are a subset of V/STOL craft that do not require runways at all. Generally, a V/STOL aircraft needs to be able to hover. Helicopters are not considered under the V/STOL classification as the classification is only used for airplanes, aircraft that achieve lift (force) in forward flight by planing the air, thereby achieving speed and fuel efficiency that is typically greater than the capability of helicopters.

Flight deck landing/take off surface of an aircraft carrier

The flight deck of an aircraft carrier is the surface from which its aircraft take off and land, essentially a miniature airfield at sea. On smaller naval ships which do not have aviation as a primary mission, the landing area for helicopters and other VTOL aircraft is also referred to as the flight deck. The official U.S. Navy term for these vessels is "air-capable ships".

Yakovlev Yak-38 VTOL strike fighter aircraft; only operational VTOL strike aircraft of the Soviet Navy

The Yakovlev Yak-38 was the Soviet Naval Aviation's only operational VTOL strike fighter aircraft in addition to being its first operational carrier-based fixed-wing aircraft. It was developed specifically for, and served almost exclusively on, the Kiev-class aircraft carriers.

Tail-sitter aircraft capable of vertical takeoff and landing on its tail, changing tilt for forward flight

A tail-sitter or tailsitter is a type of VTOL aircraft that takes off and lands on its tail, then tilts horizontally for forward flight.

Bell X-14 Experimental vertical take-off and landing (VTOL) jet aircraft

The Bell X-14 is an experimental VTOL aircraft flown in the United States in the 1950s. The main objective of the project was to demonstrate vectored thrust horizontal and vertical takeoff, hover, transition to forward flight, and vertical landing.

Convair XFY Pogo aircraft

The Convair XFY Pogo was an experiment in vertical takeoff and landing (VTOL) tail-sitter. The Pogo had delta wings and three-bladed contra-rotating propellers powered by a turboprop engine. It was intended to be a high-performance fighter aircraft capable of operating from small warships. Landing the XFY-1 was difficult, as the pilot had to look over his shoulder while carefully working the throttle to land.

Rotorcraft Heavier-than-air aircraft which generates lift over rotating wings

A rotorcraft or rotary-wing aircraft is a heavier-than-air flying machine that uses lift generated by wings, called rotary wings or rotor blades, that revolve around a mast. Several rotor blades mounted on a single mast are referred to as a rotor. The International Civil Aviation Organization (ICAO) defines a rotorcraft as "supported in flight by the reactions of the air on one or more rotors". Rotorcraft generally include those aircraft where one or more rotors are required to provide lift throughout the entire flight, such as helicopters, autogyros, and gyrodynes. Compound rotorcraft may also include additional thrust engines or propellers and static lifting surfaces.

Powered lift aircraft capable of powered vertical takeoff and landing but which operates as a fixed-wing aircraft during horizontal flight

Powered lift or powered-lift refers to a type of aircraft that can take off and land vertically and functions differently from a rotorcraft in horizontal flight.

AeroVironment SkyTote

The SkyTote is an unmanned aerial vehicle (UAV), tail-sitter Vertical Take-Off and Landing (VTOL)-fixed wing hybrid plane, which attains the advantages of both airplane designs. In order to control the vehicle when transitioning between vertical take-off to forward flight, an adaptive neural network controller was designed by Guided Systems Technologies and used on the vehicle. The vehicle was developed by AeroVironment, under a contract given by the Air Force Research Laboratory, and its primary purpose is cargo-delivery.

Saab Skeldar

The Saab Skeldar is a medium-range VTOL UAV developed by the Swedish aerospace company Saab. Missions for the Skeldar involves surveillance, intelligence gathering, light cargo transportation and electronic warfare.

IAI Panther

The Israel Aerospace Industries Panther is a tilt-rotor unmanned aerial vehicle (UAV) produced by Israel Aircraft Industries in Israel.

Aircraft can have different ways to take off and land. Conventional airplanes accelerate along the ground until sufficient lift is generated for takeoff, and reverse the process to land. Some airplanes can take off at low speed, this being a short takeoff. Some aircraft such as helicopters and Harrier Jump Jets can take off and land vertically. Rockets also usually take off vertically, but some designs can land horizontally.

ZIA UAV is a Chinese experimental UAV developed by Zhengzhou Institute Of Aeronautical Industry Management, and it is a VTOL UAV. The complete name for this Chinese experimental UAV is called Shape Varying VTOL UAV.

NWPU V/STOL UAVs are Chinese V/STOL UAVs developed by Northwestern Polytechnical University (NWPU). Most of these are proof of concept experimental UAVs to explore new technology in the arena of V/STOL.

Xplorair

The Xplorair is a project of compact VTOL aircraft without rotating airfoil from aerospace engineer Michel Aguilar, funded by the French Armed Forces procurement agency DGA and supported by various European aeronautics firms such as Dassault Systèmes, EADS Innovation Works, MBDA, Altran Technologies, Sogeti, Turbomeca, COMAT Aerospace and the Institut Pprime. Announced in 2007, the project aimed to develop a UAV prototype scheduled for flight in 2017, followed by a single-seater flying car whose commercialization could occur the decade after.

Cyclorotor specialized marine propulsion system

A cyclorotor, cycloidal rotor, cycloidal propeller or cyclogiro, is a fluid propulsion device that converts shaft power into the acceleration of a fluid using a rotating axis perpendicular to the direction of fluid motion. It uses several blades with a spanwise axis parallel to the axis of rotation and perpendicular to the direction of fluid motion. These blades are cyclically pitched twice per revolution to produce force in any direction normal to the axis of rotation. Cyclorotors are used for propulsion, lift, and control on air and water vehicles. An aircraft using cyclorotors as the primary source of lift, propulsion, and control is known as a cyclogyro. The patented application, used on ships with particular actuation mechanisms both mechanical or hydraulic, are named after the name of the German company that produces them: Voith–Schneider cycloidal propellers.

Ski-jump (aviation) Take-off ramp for aircraft

In aviation, a ski-jump is an upward-curved ramp that allows aircraft to take off from a runway that is shorter than the aircraft's required takeoff roll. By forcing the aircraft upwards, lift-off can be achieved at a lower airspeed than that required for sustained flight, while allowing the aircraft to accelerate to such speed in the air rather than on the runway. Ski-jumps are commonly used to launch airplanes from aircraft carriers that lack catapults.

References

  1. ↑ USPTO 4790497
  2. ↑ USpatent 4,790,497,Yoffe, Meir,"Point-landing method for non vertical take off and landing flying objects",issued 1988-06-28
  3. ↑ USpatent 4,753,400,Reuter, James D.,"Shipboard air vehicle retrieval apparatus",issued 1988-06-28, assigned to Pioneer Systems, Incorporated
  4. ↑ USpatent 4,311,290,Koper, Kenneth T.,"Arrestment system",issued 1982-01-19, assigned to The United States of America as represented by the Secretary of the Navy
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