2104 Flashcards
forces acting on the aircraft
drag, lift, weight, thrust
opposes the downward force of weight, is produced by the dynamic effect of the air acting on the airfoil and acts perpendicular to the flightpath through the center of lift.
lift
the combined load of the aircraft itself, the crew, the fuel, and the cargo or baggage. Weight pulls the aircraft downward because of the force of gravity. It opposes lift and acts vertically downward through the aircraft’s center of gravity (CG).
weight
the force produced by the power plant/ propeller or rotor. It opposes or overcomes the force of drag. As a general rule, it acts parallel to the longitudinal axis. However, this is not always the case, as explained later.
thrust
a rearward, retarding force caused by disruption of airflow by the wing, rotor, fuselage, and other protruding objects. Drag opposes thrust and acts rearward parallel to the relative wind.
drag
the total lift and thrust forces of a rotor are perpendicular to the rotor disk.
powered flight
most challenging part of flying a helicopter. This is because a helicopter generates its own gusty air while in a hover, which acts against the fuselage and flight control surfaces.
hovering flight
Increasing the angle of incidence of the rotor blades (pitch) while keeping their rotation speed constant generates additional lift and the helicopter ascends. Decreasing the pitch causes the helicopter to descend. In a no-wind condition in which lift and thrust are less than weight and drag, the helicopter descends vertically. If lift and thrust are greater than weight and drag, the helicopter ascends vertically.
vertical flight
the tip-path plane is tilted in the direction that flight is desired. This tilts the total lift-thrust vector sideward. In this case, the vertical or lift component is still straight up and weight straight down, but the horizontal or thrust component now acts sideward with drag acting to the opposite side.
sideward
the tip-path plane is tilted rearward, which, in turn, tilts the lift-thrust vector rearward. Drag now acts forward with the lift component straight up and weight straight down.
rearward flight
upward sweeping angle of the rotor blades as a result of lift and centrifugal force. In order for a helicopter to generate lift, the rotor blades must be turning.
coning
It states that the value of angular momentum of a rotating body does not change unless an external force is applied. In other words, a rotating body continues to rotate with the same rotational velocity until some external force is applied to change the speed of rotation. Angular momentum is the moment of inertia (mass times distance from the center of rotation squared) multiplied by the speed of rotation.
coriolis effect / law of conservation of angular momentum
state of flight where the main rotor disk of a helicopter is being turned by the action of air moving up through the rotor rather than engine power driving the rotor. In normal, powered flight, air is drawn into the main rotor disk from above and exhausted downward, but during autorotation, air moves up into the rotor disk from below as the helicopter descends.
autorotation
most common type of helicopter
single rotor system
anti-torque device
tail rotor or other anti-torque system
has two main rotor systems and no tail rotor. Usually the rear rotor is mounted at a higher position than the front rotor, and the two are designed to avoid the blades colliding, should they flex into the other rotor’s pathway.
tandem rotor helicopter
The rotor discs are slightly tilted toward each other to provide control along the vertical axis during the hover. This configuration, which is mainly used for larger helicopters, has the advantage of being able to support more weight with shorter blades.
tandem rotor helicopter
two main rotors mounted on one mast, sharing the same axis of rotation but turning in opposite directions, one on top of the other. The control along the vertical axis is produced as a result of different lifts, thus differential torque, of the two rotor discs.
co-axial rotor system
The helicopter will yaw to the left if the clock wise rotating rotor produces more lift, and it will yaw to the right if more lift is produced by the counter-clock wise rotating rotor.
co-axial rotor system
two rotors turning in opposite directions and mounted on two masts slightly inclined towards each other, so that the blades intermesh (without colliding)
synchropter
two horizontals, counter-rotating rotors are mounted side-by-side on a helicopter (or transverse rotorcraft). The anti-torque effect is provided by the opposing rotation of the two main rotors.
side by side configuration
The rotors are mounted at the edge of the wings, on nacelles that rotate in order to transition the rotors from the vertical position (to provide vertical lift like a side by side rotor configuration helicopter), to the horizontal position (where they provide horizontal lift, or thrust, just like in airplanes).
tilt rotor configuration
is a helicopter system which avoids the use of a tail rotor. uses jet thrust rather than blades to provide directional stability and reduce noise, providing the world’s quietest helicopters.
NOTAR (NO TAIL ROTOR CONFIGURATION)
basic helicopter flight control system
cyclic control, collective control, anti-torque pedals
changes the tilt of the main rotor for control about the longitudinal axis (roll) and lateral axis (pitch).
cyclic pitch control
varies the lift of the main rotor by increasing or decreasing the pitch of all blades at the same time. It is also used in coordination with cyclic pitch control to regulate the airspeed of the helicopter.
collective pitch control
mounted on the collective pitch grip and is operated by rotating the motorcycle–type grip.
throttle control
Rotating the grip outboard ________ rpm, and rotating it inboard _________ rpm.
increases, ecreases
provides for movement about the vertical axis (yaw). This movement is controlled by the directional control pedals in the cockpit.
anti-torque pedals
The Anti-Torque Pedals, also known as
“torque control”
is a sensing device that senses rotor and engine r.p.m. and makes the necessary adjustments in order to keep rotor r.p.m. constant. In normal operations, once the rotor r.p.m. is set, the governor keeps the r.p.m. constant, and there is no need to make any throttle adjustments.
governor
mechanical connection between the collective lever and the engine throttle. When the collective lever is raised, power is automatically increased and when lowered, power is decreased. This system maintains r.p.m. close to the desired value, but still requires adjustment of the throttle for fine tuning.
correlator
is a heavier- than-air flying machine that generates lift using rotary wings or rotor blades, which revolve around a mast.
rotorcraft
is a heavier- than-air flying machine that generates lift using rotary wings or rotor blades, which revolve around a mast.
Rotorcraft
Several rotor blades mounted on a single mast are referred to as a
Rotor
The earliest references for vertical flight came from
China.
Chinese top
Chinese bamboo helicopters have been here sinc
400 BC
Chinese children have played with
Bamboo flying toys or Chinese top
This bamboo-copter is spun by _____ a stick attached to a rotor
Rolling
Trade from the Far East resulted in the Chinese toys reaching Europe in the early Renaissance, likely inspiring Leonardo da Vinci to create a drawing called the
Aerial Screw
Year of Aerial Screw
1483 to 1486
Designed a model flying machine using coaxial propellers and a coiled spring for propulsion
Gustave Vicomte de Ponton d’Amècourt
a model flying machine using coaxial propellers and a coiled spring for propulsion
Helicopteres
The helicopter that considered as America’s first production helicopter.
SIKORSKY’S XR-4
A helicopter that used two 6.1 meters (20 ft) counter-rotationg rotors driven by a 24 hp (18 kW) Antoniette Engine
Cornu Helicopter
The machine that achieved its first vertical ascent on either
August 24 or September 29
Gyroplane No. 1
Most common type of helicopter configuration.
Single Rotor Configuration
Two main rotors mounted on one mast, sharing the same axis of rotation but turning in opposite directions.
Co-axial rotor
When was the AH-64 “Apache” helicopter performed well as both a tank killer and fast-assault vehicle.
1991 Gulf War
has two main rotor systems and no tail rotor, usually the rear rotor is mounted at a higher position than the front rotor.
Tandem Rotor
considered to be the first controlled helicopter flight.
Autogiro No. 4
most popular helicopter in the U.S. military
UH-60
On what datw Sikorsky took the VS-300 flight
September 14, 1939
A separate rotor that overcomes torque.
Tail rotor
Where is collective pitch control located
left side of the pilot’s seat and is operated with the left hand.
The rotorcraft had a 45-horsepower engine, just powerful enough to hover for 2 minutes.
Gyroplane No.1
