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Bell hoped for the Army to go with their service life extension models instead of the AAS program. The OH-58F is an "obsolescence upgrade", while the Block II was seen as the performance upgrade. This gave the Army financial flexibility via the option of upgrading the Kiowa to the OH-58F and later continuing to the Block II when there were ...
Detail of Leonardo's "aerial screw" The page of Paris Manuscript B, folio 83v, that depicts Leonardo's aerial screw, held by the Institut de France The Italian polymath Leonardo da Vinci drew his design for an "aerial screw" in the late 1480s, while he was employed as a military engineer by Ludovico Sforza, Duke of Milan from 1494 to 1499.
No.II had two two-blade rotors of 7.85 m (25.75 ft) diameter and also had fixed wings. Powered by a 41 kW (55 hp) Renault engine, it was reported to have flown successfully more than once in 1908. No.II was damaged in a heavy landing and was rebuilt as the No.IIbis. It flew at least once in April 1909 before being destroyed when the company's ...
An example of two-blade rotor is the Bell 212, and four blade version of this helicopter is the Bell 412. [23] An example of the effect of rotor blade number is the UH-72 ( EC145 variant ); the A model had four blades, but the UH-72B was changed to five blades which reduced vibration. [ 24 ]
A quadcopter, also called quadrocopter, or quadrotor [1] is a type of helicopter or multicopter that has four rotors. [ 2 ] Although quadrotor helicopters and convertiplanes have long been flown experimentally, the configuration remained a curiosity until the arrival of the modern unmanned aerial vehicle or drone.
In a stationary hover, each rotor blade will experience the same airspeed at a constant RPM. In forward flight conditions, one rotor blade will be moving into the oncoming air stream while the other moves away from it. At certain airspeeds, this can create a dangerous condition in which the receding rotor blade stalls, causing unstable flight. [5]
The Sikorsky CH-53E Super Stallion is a heavy lift helicopter operated by the United States military.As the Sikorsky S-80, it was developed from the CH-53 Sea Stallion, mainly by adding a third engine, adding a seventh blade to the main rotor, and canting the tail rotor 20°.
A rotor blade produces more lift in the advancing half. As a blade moves toward the direction of flight, the forward motion of the aircraft increases the speed of the air flowing around the blade until it reaches a maximum when the blade is perpendicular to the relative wind. At the same time, a rotor blade in the retreating half produces less ...