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The Bell Boeing Quad TiltRotor (QTR) is a proposed four-rotor derivative of the Bell Boeing V-22 Osprey developed jointly by Bell Helicopter and Boeing.The concept is a contender in the U.S. Army's Joint Heavy Lift program (a part of Future Vertical Lift program).
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.
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 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 ...
Since the rotors can be configured to be more efficient for propulsion (e.g. with root-tip twist) and it avoids a helicopter's issues of retreating blade stall, the tiltrotor can achieve higher cruise speeds and takeoff weights than helicopters. A tiltrotor aircraft differs from a tiltwing in that only the rotor pivots rather than the entire wing.
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]
A 21-inch (530 mm) fuselage extension just forward of the main door was added for more capacity. The UH-1Y features upgraded transmissions and a digital cockpit with flat-panel multifunctional displays. Compared to the UH-1N, the Y-model has an increased payload, almost 50% greater range, a reduction in vibration, and higher cruising speed.
The AeroVironment Switchblade is a miniature loitering munition designed by AeroVironment and used by several branches of the United States military.Small enough to fit in a backpack, the Switchblade launches from a tube, flies to the target area, and crashes into its target while detonating its explosive warhead.