Chapter 22

Air Vehicular Systems

Objectives

• After reading the chapter and reviewing the materials presented the students will be able to understand:

• Uses of jet engine.• Common type of aircraft instrumentation.• Types of stability of an aircraft.

Propulsion Systems

• Reciprocating engines: Typical aircraft engines have 4 or 6 cylinders. The engine is used to drive a propeller. The propeller provides thrust. Propeller systems provide good fuel economy. The efficiency is a tradeoff for speed (760 miles per hour).

• Jet Engines: are able to travel at much higher rates of speed than reciprocating engines. The four types of gas turbine engines are turbojet, turbofan, turboprop, and afterburning turbojet engines. Turbofan engines are widely used on commercial passenger airplanes because they are efficient as well as powerful at low speeds. Afterburning turbojet engines are used on fighter jets and supersonic transports(SSTs) to provide additional thrust.

Guidance Systems

• Aeronautical Charts: show elevations of hills and mountains, as well as the locations of airports and other landing areas. They have special markings that locate prohibited areas (military installations) and restricted areas (artillery ranges).

• Instruments: Pilots follow visual flight rules (VFR) when weather conditions allow. Instrument flight rules (IFR) are followed when weather conditions do not allow pilots to navigate visually.

• Electronic Navigation Equipment: Instruments allow pilots to find their current direction, speed, and altitude.

• Instrument Landing System(ILS): allows pilots to land in all types of weather conditions.

• Global Positioning System (GPS): GPSs will eventually be used for navigation and landing of aircraft.

Control Systems

• Lighter-than-air vehicle control systems: Hot air balloons can only control the vertical flight of the balloon. Blimps and dirigibles can control both vertical and horizontal dimensions of flight.

• Heavier-than-air vehicle control systems: There are 3 types of stability: directional, lateral, and longitudinal. The axes are 90 degrees from each other (fig 22-17, page 530). Directional stability allows the airplane to fly in a straight line. The horizontal stabilizer or tail fin is used to provide directional stability (yaw: side to side motion).Lateral stability is used to overcome the tendency of the plane’s wings to dip on either side. This motion is known as roll. Longitudinal stability is the ability to fly the airplane without the nose moving up or down. Pitch is the up and down movement of the aircraft.

Suspension Systems

• Wheels are attached to the aircraft with struts.• Struts are designed so they absorb the shock of

the airplane touching the ground.• Large planes use hydraulic shock absorbing

devices similar to the ones used on automobile suspensions.

• Airplanes designed to land on water use pontoons instead of wheels.

• The shape of a plane’s wing is called an air foil (fig 22-27, page 535). The airfoil generates lift.

Structural Systems

• Lighter-than-air structural systems: Blimps are non rigid air ships. Cables running within the envelope (lightweight polyester or fabric filled with helium) attach the cars or gondolas. The gondolas have an area for passengers and the pilots and have engines mounted on each side. The stabilizers are mounted to the rear of the envelope. Hot air balloons are made of rip stop nylon. Steel cables running through the fabric are attached to the basket holding the fuel and occupants. The pilot heats the air inside the envelope with large propane fuel burners. Rigid airships (zeppelins) have a stiff framework that serve as hulls with a number of airtight compartments filled with helium gas. The propulsion systems and stabilizers are attached to the hull using mounting brackets.

• Heavier-that-air Vehicle Structural Systems: Airplane structural systems – the fuselage is the large hollow section that holds the other parts of the plane together. It contains the passenger cabin, the cargo hold, and a cockpit. The other systems are the tail section and wings. Helicopter structural systems – the two main sections of the helicopter are the tail section and cabin.

Support Systems

• Airports are facilities that house most of the support systems for air transportation.

• The communication centers and control towers keep track of all the airplanes within their airspace.

• Runaways: Small airports use a single runaway. A taxiway connects a runaway to the terminal. Runway lighting helps guide pilots.

• Airport Terminals: Passenger and cargo terminals are often very large at airports in major cities. Cargo terminals at airports are usually separate from passenger terminals.

• Aircraft Maintenance: The FAA requires thorough inspections on a regular basis. Normal vehicle maintenance must also be performed on aircraft.

Summary• Reciprocating engines: Typical aircraft engines have 4 or 6 cylinders. Propeller

systems provide good fuel economy.• Jet Engines: are able to travel at much higher rates of speed than reciprocating

engines. • Aeronautical Charts: show elevations of hills and mountains, as well as the

locations of airports and other landing areas. • Instrument Landing System(ILS): allows pilots to land in all types of weather

conditions.• Global Positioning System (GPS): GPSs will eventually be used for navigation and

landing of aircraft. • There are 3 types of stability: directional, lateral, and longitudinal. The axes are 90

degrees from each other. • Airports are facilities that house most of the support systems for air transportation.• The communication centers and control towers keep track of all the airplanes

within their airspace.

Home Work

1. What are the advantages of jet engines?

2. What do aeronautical charts show?

3. What are the 3 types of stability in an aircraft?