1. What engine is heavier?

2. What about their size?

3. What engine develops higher speed?

4. What engine consumes more fuel?

5. What airplanes are powered by turboprop engines?

6. What airplanes are powered by turbojet engines?

Exercise 13. Make questions to the underlined words

1. Types of engines, their number and location on the airplane depend on the airplane performances.

2. Jet engines fall into two main classes: air-breathing engines and rocket engines.

3. The jet is produced by the combustion of the fuel in the compressed air.

4. Rockets find extensive use.

5. The simplest type of air-breathing engines is the ramjet engine.

6. The main components of the ramjet are: the diffuser, the combustion chamber and the jet nozzle.

7. Turbofans are widely used in aviation, especially in large multi-engine aircraft.

Exercise 14. Read the texts and write annotations.

A) The Ramjet Engine

The simplest type of jet engine is the ramjet. This engine consists of a diffuser, a combustion chamber, a discharge nozzle. The function of a diffuser is to convert the kinetic energy of the entering air into a pressure. The diffuser delivers the air at a static pressure higher than atmospheric pressure to the combustion chamber. There fuel is mixed with the air and ignited.

The burning causes the specific volume of the air to increase. The air is accelerated in the combustion chamber, where it burns at constant pressure to a high temperature. High temperature gases are delivered to the discharge nozzle to produce exit velocity greater than the entrance velocity. The fuel used in this type of engine is usually a liquid one.

Theoretically, ramjet operation is limited to altitudes below 90000 feet because atmospheric oxygen is necessary for combustion. The velocity that can be obtained by a ramjet engine is unlimited, theoretically

Really the faster it travels the better it operates and the more thrust it develops. Its speed is limited, however, at Mach 5,0 because the skin temperature has a harmful effect on the metals used in construction.

Ramjet engines are used in guided missiles. Ramjets are sometimes used experimentally on helicopters and in pods on fighters and bombers.

B)The Turbojet Engine

This engine consists of a diffuser, a mechanical compressor, a combustion chamber, a mechanical turbine and a discharged nozzle.

The function of a diffuser is to transform the kinetic energy of the entering air into a static pressure. The diffuser delivers its air to the mechanical compressor which compresses the air and delivers it to the combustion chamber. The high temperature gases then enter the turbine.

The turbine is directly connected to the compressor, and all the power developed by the turbine is absorbed by the compressor and the auxiliary apparatus. The main function of the turbine is to provide power for the mechanical compressor. After the gases leave the turbine, they enter the discharged nozzle and are ejected with a velocity greater than the flight velocity. This produces a thrust for propulsion.

The turbojet engine is product of one of the most intensive engineering development programs in aviation history. Since its introduction, the increase in its performance has been phenomenal and it is now in mass production for various airplanes.

It is now the standard power plant for nearly all high-speed military fighters and bombers.