Helicopter

A helicopter is an aircraft that is lifted and propelled by one or more horizontal rotors; each rotor consists of two or more rotor blades. Helicopters are the true flying machine. Helicopters are classified as rotor craft or rotary wing aircraft to distinguish them from fixed wing aircraft because the helicopters derive its source of lift from the rotor blades rotating around a mast.  

The ability of helicopter is to move laterally in any direction or rotate 360 degree make them exciting to fly. Helicopters are used for transportation, construction, fire fighting, search and rescue, and a variety of other jobs that require its special capabilities

Forces Acting on the Aircraft

        Once a helicopter leaves the ground, it is acted upon by aerodynamic forces

a)      Thrust- the forward 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

b)      Drag- 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

c)      Weight- The combined load of the aircraft itself, the crew, the fuel and cargo. Weight pulls the aircraft downwards because of the force of gravity. It oppose lift force and acts vertically downward through the aircraft’s center of gravity

d)      Lift- Opposes the downward force of weight, is produced by the dynamic effect of the air acting on the air foil and acts perpendicular to the flight path through the center of lift

Bernoulli’s principle

Bernoulli’s principle describes the relationship between internal fluid pressure and fluid velocity. It is a statement of the law of conservation of energy and helps explain why an air foil develops an aerodynamic force. The concept of conservation of energy states energy cannot be created or destroyed and the amount of energy entering a system must also exit.

Helicopter