... If a helicopter was designed with a single rotor it would be
very difficult to control.
The rotor, spinning in one direction, sends the body twisting in
the opposite direction.
To overcome this effect, some helicopters are designed with
two rotors, each turning in the opposite direction; this ...
... Consider a typical element or strip shown below. The blade “sees” an in-plane
velocity UT, that is tangential to the plane of rotation. The magnitude of U T is, of
course, r, where r is the radial position of the strip. This element has a pitch
angle equal to . That is, the angle between the plane ...
... the speed of the rotor in revolutions per
minute (rpm) and the radius of rotation
(ie the distance from the axis of rotation).
The equations that permit calculation of the
RCF from a known rpm and radius of
rotation, and calculation of the rpm from a
known RCF and radius are shown in Table 1.
The RC ...
... mounted on outriggers were used for the
Focke-Achgelis Fw-61 which was initially
flown in Germany in 1936 and is considered to be the world’s first practical
helicopter. Another German helicopter,
the Flettner synchrocopter was produced
for military use between 1942 and 1945.
This aircraft, sometime ...
... In forward flight, air flows opposite the flight path of the aircraft. The velocity of the flow of air equals the
forward speed of the helicopter. Because the blades of the helicopter turn in a circular pattern, the velocity
of the airflow across a blade depends on the position of the blade in the r ...
... condition that will cause the nose to pitch up. This is due to gyroscopic
precession, stall on the right side, reaction is 90 degrees later causing
loss of lift over the tail and the nose to pitch up.
At this point the helicopter may start to roll, usually to the left but not
A helicopter main rotor or rotor system is the combination of several rotary wings (rotor blades) and 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 a swashplate connected to the helicopter flight controls. Helicopters are one example of rotary-wing aircraft (rotorcraft).