Helicopter Aerodynamics
Helicopters are the most versatile aircraft today because of their ability to use three-dimensional space. Their flexibility allows them to fly backwards, hover, and rotate in air. This makes helicopters a lot more complicated than other aircraft aerodynamically and from a pilot's point of view. A modern helicopter's power source comes from a turbo-shaft engine, which does not produce thrust. Instead they create mechanical power to drive a shaft that connects to the main rotor. The shape of the turbine blades determines whether thrust is used to drive a shaft, or if most of the thrust is used to propel the aircraft and send a small amount of drive power to the compressor. In helicopters they are used the drive the shaft. These engines are light, powerful, and economical. To get the power from the turbo-shaft engine to the main rotor, a gearbox transfers the engine power to a transmission. The transmission reduces the revolutions per minute (RPM) from thousands to one-hundreds. This increases the torque so it can be accepted by the rotor system. The transmission gives direct power to the rotors. The tail rotor is powered the same way.Once the main rotor is in motion is acts as a wing to create lift. The rotor wings on a heli
This is required because precession causes a nose down tendency and because the tilted disk produces less vertical lift to counteract gravity. When the rotor system begins to turn, the blade starts to rise from the static position because of the centrifugal force. The cyclic will try to move backward in the pilots hand as the rotor system wants to oppose the force. In rotary-wing aircraft, centrifugal force is the dominant force affecting the rotor system. The tail rotor produces sideways thrust that counteracts the engine's ability to spin the body. This is compensated by adding left cyclic control inputs. The rotating swash plate rotates with the drive shaft and the rotor's blades because of the links that connect the rotating plate to the drive shaft. Once the aircraft starts to roll, a downward collective movement is the only thing that will stop the forces in action from flipping the aircraft on its side. Gyroscopic precession is a phenomenon occurring in rotating bodies in which an applied force is manifested 90 degrees later in the direction of rotation from where the force was applied. The cyclic control changes the entire rotor's angle of attack to move forward, backward, left and right. This happens since the front of the rotor system is flying in clean air first, and the aft portion of the rotor system is still not in clean air. copter are shaped the same as an airfoil on an airplane, but a lot narrower so they can spin faster. The rotating blades of a helicopter produce very high centrifugal loads on the rotor head and blade attachment assemblies. Although precession is not a dominant force in rotary-wing aerodynamics, it must be reckoned with because turning rotor systems exhibit some of the characteristics of a gyro. At the tip of the blade, the leading edge may point down while at the root of the blade, the leading edge may point up.
Common topics in this essay:
,
Effectiveness LTE,
Lift ETL,
rotor system,
main rotor,
tail rotor,
swash plate,
gross weight,
drive shaft,
angle attack,
rotating swash,
blade root,
settling power,
rotating swash plate,
rotor blade root,
tendency tilted disk,
main rotor system,
nose tendency tilted,
|
Acceptance Essays
