**4. Rotary-wing aircraft (RWA)**

A RWA (also known as helicopter) does not have wings, but its rotor blades perform an identical role of the wings of an aeroplane. When rotor blades spin, flow of air takes place over the wings or rotor blades—hence the name rotary-wing aircraft. The magnitude of the lift can be changed by altering the angle of attack (AOA) of air over the rotor blades. The AOA is changed by mechanically increasing or decreasing the rotor blade pitch angle. For this, the pilot uses a control called 'collective' which is on his left side in the cockpit. The pilot can change the altitude of flying as well as hover the helicopter at a place by operating the collective.

Another control known as 'cyclic' is used to move the helicopter in different directions. The cyclic is operated by the pilot using his right hand. When cyclic is operated, the pitch angle of the rotor blades is changed, but it alters each blade individually by a different amount. When cyclic is operated, the total vertical force produced by rotor blades is inclined, the vertical component keeps the helicopter afloat and horizontal component moves the helicopter in the desired direction. The helicopter cyclic control system is designed in such a way that when the cyclic is moved forward, the helicopter moves forwards, when it is moved sideways the helicopter moves sideways and when cyclic is moved aft the helicopter moves backwards (which a fixed wing aircraft cannot do). The third helicopter control is the yaw pedals. These alter the pitch angle of the tail rotor—the small rotor at the end of the helicopter. Doing this enables the pilot to turn the helicopter either left or right (yaw) [8].

## **4.1 Military application of helicopters**

The helicopter is a very useful machine for military applications. Due to its design features, helicopters can hover at a point, fly at very low altitude and above all take off from the land at any place it desires. Military helicopters are also installed with protective armor/windshield against bullets. Some of the typical applications are:

1.*Attack helicopter*—attack helicopters are used in the antitank and close support roles. These helicopters are equipped with antitank-guided missiles, guns and rockets. To enable them to find and identify their targets, some modern attack helicopters are equipped with very capable sensors such as a millimetre wave radar system.


**13**

*Military Aviation Principles*

vehicle [9, 10].

**5.2 Military UAV**

**5.1 Application of UAV**

*DOI: http://dx.doi.org/10.5772/intechopen.87087*

**5. Unmanned aerial vehicle (UAV)**

aviation business applications include:

1.Aerial photography, film, video, still, etc.

2.Agriculture crop monitoring and spraying

compensate for uncertainties over airworthiness.

**5.3 Military application of UAV**

These are designed to possess:

b.All weather operation

3.Conservation, pollution and land monitoring

4.Electricity companies for their power line inspection.

dropping as well as suppression of enemy air defence (SEAD).

a.High accuracy and probability to 'strike the target capability'

c.High speed and manoeuverability for war zone penetration

d.Autonomous programme with rerouting facility

An airborne vehicle capable of being flown without a pilot on board is termed as pilotless or unmanned aerial vehicle (UAV). UAVs are broadly in two types, namely, remotely piloted vehicle (RPV) and autonomous and preprogramed air

UAV has the potential to serve varieties of application both in civil and military uses. These include border and port security, homeland surveillance, scientific data collection, cross-country transport and telecommunication services. Many non-

UAVs used for armed forces, police, border security and coast guard are considered owned by the state commonly known as military UAV. These UAVs are under direct control of the government of the state, and the state is directly responsible for safety of operation and third-party damage in the event of UAV failure. This direct control of operations is a significant advantage of operation in segregated space at the same time accepting a safety of operation by imposing operational restriction to

UAV in military is used as a force multiplier for carrying out very dull, dirty missions that are long and considered very hazardous and risky for manned flight. Some of these tasks are round-the-clock reconnaissance, surveillance and target acquisition (RSTA); nuclear, biological and chemical (NBC) war; and combat search and rescue (CSAR) operation. In offensive role UAV can be employed for arm

Unmanned combat air vehicle (UCAV) is used for offensive war application.
