A Flettner rotor is a smooth cylinder with disc end plates which is spun along its long axis and, as air passes at right angles across it, the Magnus effect causes an aerodynamic force to be generated in the direction perpendicular to both the long axis and the direction of airflow. [1] The rotor sail is named after the German aviation engineer and inventor Anton Flettner, who started developing the rotor sail in the 1920s. [2]
In a rotor ship, the rotors stand vertically and lift is generated at right angles to the wind, to drive the ship forwards.
In a rotor airplane, the rotor extends sideways in place of a wing and upwards lift is generated.
The Magnus effect is named after Gustav Magnus, the German physicist who investigated it. It describes the force generated by fluid flow over a rotating body, at right angles to both the direction of flow and the axis of rotation. This force on a rotating cylinder is known as Kutta–Joukowski lift, after Martin Kutta and Nikolai Zhukovsky (or Joukowski), who first analyzed the effect. [3]
The Flettner rotor is just one form of the Magnus rotor, which in general need not be cylindrical. [1]
A rotor ship uses one or more Flettner rotors mounted upright. They are rotated by the ship's engines, and act like sails to propel the ship under wind power. A conventionally-powered underwater propeller may be provided for additional operational flexibility.
An early prototype, the Baden Baden (formerly the Buckau), crossed the Atlantic in 1925, but interest was not revived until energy saving became a major concern in the new millennium. The E-Ship 1 was launched in 2008, and new vessels continue to appear. Since then, multiple rotor installations have been completed, including tilting rotors to allow passage beneath bridges. [4] Typically, rotor sails have been reported to generate 5-20% fuel savings. [4]
A Flettner rotor mounted beneath the waterline of a ship's hull and emerging laterally will act to stabilize the ship in heavy seas. By controlling the direction and speed of rotation, strong lift or downforce can be generated. [5] The largest deployment of the system to date is in the motor yacht Eclipse.[ citation needed ]
Some flying machines have been built which use the Magnus effect to create lift with a rotating cylinder at the front of a wing, allowing flight at lower horizontal speeds. [3]
An early attempt to use the Magnus effect for a heavier-than-air aircraft was made in 1910 by a US member of Congress, Butler Ames of Massachusetts.[ citation needed ]
A later example was the Plymouth A-A-2004 in the early 1930s, built by three inventors in New York state. [6]
French designer Jean de Chappedelaine developed his Aérogyre at much the same time. A prototype, based on a modified Caudron C.270 Luciole, was flown in 1934 with the wing rotor stationary. It crashed on its next flight, but whether the wing was rotating during that flight is unknown. [7]
The Flettner rotor inspired Sigurd Johannes Savonius to invent [8] a spinning ventilation device after a collaboration between the two inventors. Anton Flettner's company Flettner Ventilator Limited acquired Savonius' patent[ citation needed ] and still sells them in the United Kingdom. [9] The devices are often referred to as "Flettner ventilators" even though the mechanism more closely resembles a Savonius wind turbine, which was a 1924 invention that resulted from the same collaboration.
When a fluid flows around an object, the fluid exerts a force on the object. Lift is the component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag force, which is the component of the force parallel to the flow direction. Lift conventionally acts in an upward direction in order to counter the force of gravity, but it is defined to act perpendicular to the flow and therefore can act in any direction.
A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is expressed as its lift-to-drag ratio. The lift a wing generates at a given speed and angle of attack can be one to two orders of magnitude greater than the total drag on the wing. A high lift-to-drag ratio requires a significantly smaller thrust to propel the wings through the air at sufficient lift.
The Magnus effect is an observable phenomenon commonly associated with a spinning object moving through a fluid. A lift force acts on the spinning object. The path of the object may be deflected in a manner not present when the object is not spinning. The deflection can be explained by the difference in pressure of the fluid on opposite sides of the spinning object. The strength of the Magnus effect is dependent on the speed of rotation of the object.
Anton Flettner, Flugzeugbau GmbH was a German helicopter and autogyro manufacturer during World War II, founded by Anton Flettner.
Savonius wind turbines are a type of vertical-axis wind turbine (VAWT), used for converting the force of the wind into torque on a rotating shaft. The turbine consists of a number of aerofoils, usually—but not always—vertically mounted on a rotating shaft or framework, either ground stationed or tethered in airborne systems.
Anton Flettner was a German aviation engineer and inventor. Born in Eddersheim, Flettner made important contributions to airplane, helicopter, vessel, and automobile designs.
A rotor ship is a type of ship designed to use the Magnus effect for propulsion. The ship is propelled, at least in part, by large powered vertical rotors, sometimes known as rotor sails. German engineer Anton Flettner was the first to build a ship that attempted to tap this force for propulsion, and ships using his type of rotor are sometimes known as Flettner ships.
On a helicopter, the main rotor or rotor system is the combination of several rotary wings with a control system, that generates the aerodynamic lift force that supports the weight of the helicopter, and the thrust that counteracts aerodynamic drag in forward flight. Each main rotor is mounted on a vertical mast over the top of the helicopter, as opposed to a helicopter tail rotor, which connects through a combination of drive shaft(s) and gearboxes along the tail boom. The blade pitch is typically controlled by the pilot using the helicopter flight controls. Helicopters are one example of rotary-wing aircraft (rotorcraft). The name is derived from the Greek words helix, helik-, meaning spiral; and pteron meaning wing.
Airborne wind energy (AWE) is the direct use or generation of wind energy by the use of aerodynamic or aerostatic lift devices. AWE technology is able to harvest high altitude winds, in contrast to wind turbines, which use a rotor mounted on a tower.
The Kutta–Joukowski theorem is a fundamental theorem in aerodynamics used for the calculation of lift of an airfoil translating in a uniform fluid at a constant speed large enough so that the flow seen in the body-fixed frame is steady and unseparated. The theorem relates the lift generated by an airfoil to the speed of the airfoil through the fluid, the density of the fluid and the circulation around the airfoil. The circulation is defined as the line integral around a closed loop enclosing the airfoil of the component of the velocity of the fluid tangent to the loop. It is named after Martin Kutta and Nikolai Zhukovsky who first developed its key ideas in the early 20th century. Kutta–Joukowski theorem is an inviscid theory, but it is a good approximation for real viscous flow in typical aerodynamic applications.
The cyclogyro, or cyclocopter, is an aircraft configuration that uses a horizontal-axis cyclorotor as a rotor wing to provide lift and sometimes also propulsion and control. In principle, the cyclogyro is capable of vertical take off and landing and hovering performance like a helicopter, while potentially benefiting from some of the advantages of a fixed-wing aircraft.
A Flettner airplane is a type of rotor airplane which uses a Flettner rotor to provide lift. The rotor comprises a spinning cylinder with circular end plates and, in an aircraft, spins about a spanwise horizontal axis. When the aircraft moves forward, the Magnus effect creates lift.
A windmill ship, wind energy conversion system ship or wind energy harvester ship propels itself by use of a wind turbine to drive a propeller.
The E-Ship 1 is a roll-on/lift-off (RoLo) cargo ship that made its first voyage with cargo in August 2010. The ship is owned by the third-largest wind turbine manufacturer, Germany's Enercon GmbH. It is used to transport wind turbine components. The E-Ship 1 is a Flettner ship: four large rotorsails that rise from its deck are rotated via a mechanical linkage to the ship's propellers. The sails, or Flettner rotors, aid the ship's propulsion by means of the Magnus effect – the perpendicular force that is exerted on a spinning body moving through a fluid stream.
A tumblewing or "tumble wing" or "tumbling wing" is a glider or kite wing design which rotates about an axis transverse to the apparent wind, not necessarily horizontal. Tumble wings are frequently employed in wind turbines, and are also used in some types of confetti.
Sigurd Johannes Savonius was a Finnish architect and inventor. He is known especially for the Savonius wind turbine, which he invented in 1924.
A rotor wing is a lifting rotor or wing which spins to provide aerodynamic lift. In general, a rotor may spin about an axis which is aligned substantially either vertically or side-to-side (spanwise). All three classes have been studied for use as lifting rotors and several variations have been flown on full-size aircraft, although only the vertical-axis rotary wing has become widespread on rotorcraft such as the helicopter.
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 or cyclocopter. A unique aspect is that it can change the magnitude and direction of thrust without the need of tilting any aircraft structures. The patented application, used on ships with particular actuation mechanisms both mechanical or hydraulic, is named after German company Voith Turbo.
A vertical-axis wind turbine (VAWT) is a type of wind turbine where the main rotor shaft is set transverse to the wind while the main components are located at the base of the turbine. This arrangement allows the generator and gearbox to be located close to the ground, facilitating service and repair. VAWTs do not need to be pointed into the wind, which removes the need for wind-sensing and orientation mechanisms. Major drawbacks for the early designs included the significant torque ripple during each revolution, and the large bending moments on the blades. Later designs addressed the torque ripple by sweeping the blades helically. Savonius vertical-axis wind turbines (VAWT) are not widespread, but their simplicity and better performance in disturbed flow-fields, compared to small horizontal-axis wind turbines (HAWT) make them a good alternative for distributed generation devices in an urban environment.
The Plymouth A-A-2004 is a rotor aircraft inspired by the Flettner rotor, a type of rotor that uses the Magnus Effect to produce lift. Built specifically for Zaparka in 1930 by three anonymous American inventors, this aircraft showcased the innovative use of the Magnus Effect in aviation, leading to successful flights over Long Island Sound