Exsercises

1. Write 10 questions to each text from the unit.

2. Write out of each text the sentences with the verbs in the Passive voice.

3. Translate any part of the texts (1500 signs) in writing.

4. Retell text about «The MiG-29 fighter’s family».

5. Speak on «Armament».

Unit VIII. Engines

An engine produces a force which acts toward the rear of the aircraft which «thrusts» the aircraft forward. For this reason, the force produced by the engine is called thrust. Thrust is the most important force acting on an aircraft, because regardless of the type of aircraft, ALL need some type of thrust to propel them aloft. Even unpowered aircraft such as gliders need a tow plane to provide an external force to pull the aircraft into the air, where it can obtain airflow over the wings to provide the necessary lift to remain airborne. Hang gliders use foot power to initiate movement prior to «leaping» off a cliff. The most common means of developing thrust on powered airplanes comes from propellers or jets. Whether an aircraft has a propeller, a turbojet, or a turbofan, all of these produce thrust by accelerating a mass of air to the rear of the aircraft. The movement of this air to the rear creates an unbalanced force pushing the aircraft forward.

The Wright brothers made many important things come together for their historic first heavier-than-air flight. One of the most vital was an engine that efficiently produced thrust while not weighing too much. They used propellers – the only effective means available of transferring an internal combustion engine’s output into push or pull for the airplane. Propellers are essentially revolving wings situated so that the lift they produce is used to pull or push the airplane.

Most modern high-speed aircraft use a very different type of engine – the jet engine. Jet engines not only look different from propellers, they operate in a very different manner as well. More like rocket engines, jets produce thrust by burning propellant (jet fuel mixed with air) and forcing the rapidly expanding gases rearward. In order to operate from zero airspeed on up, jets use enclosed fans on a rotating shaft to compress the incoming air (and suck it in if the airplane is not going very fast) and send it into the combustion chamber where the fuel is added and ignited. The burning gases keep the shaft turning by rotating a fan before exiting the engine.

How a Jet Engine Works

Jet engines move the airplane forward with a great force that is produced by a tremendous thrust and causes the plane to fly very fast.

Jet engines, which are also called gas turbines, work on the same principle. The engine sucks air in at the front with a fan. A compressor raises the pressure of the air. The compressor is made up of fans with many blades and attached to a shaft. The blades compress the air. The compressed air is then sprayed with fuel and an electric spark lights the mixture. The burning gases expand and blast out through the nozzle, at the back of the engine.

The image above shows how the air flows through the engine. The air goes through the core of the engine as well as around the core. This causes some of the air to be very hot and some to be cooler. The cooler air then mixes with the hot air at the engine exit area.

A jet engine operates on the application of Sir Isaac Newton’s third law of physics: for every action there is an equal and opposite reaction. This is called thrust. This law is demonstrated in simple terms by releasing an inflated balloon and watching the escaping air propel the balloon in the opposite direction. In the basic turbojet engine, air enters the front intake and is compressed, then forced into combustion chambers where fuel is sprayed into it and the mixture is ignited. Gases which form expand rapidly and are exhausted through the rear of the combustion chambers exert equal force in all directions, providing forward thrust as they escape to the rear. As the gases leave the engine, they pass through a fan-like set of blades (turbine) which rotates the turbine shaft. This shaft, in turn, rotates the compressor, thereby bringing in a fresh supply of air through the intake. Engine thrust may be increased by the addition of an afterburner section in which extra fuel is sprayed into the exhausting gases which burn to give the added thrust. At approximately 400 mph, one pound of thrust equals one horsepower, but at higher speeds this ratio increases and a pound of thrust is greater than one horsepower. At speeds of less than 400 mph, this ratio decreases.

In a turboprop engine, the exhaust gases are also used to rotate a propeller attached to the turbine shaft for increased fuel economy at lower altitudes. A turbofan engine incorporates a fan to produce additional thrust, supplementing that created by the basic turbojet engine, for greater efficiency at high altitudes. The advantages of jet engines over piston engines include lighter weight with greater power, simpler construction and maintenance with fewer moving parts, and efficient operation with cheaper fuel.

Turbojet Engines

The turbojet is the basic engine of the jet age. Air is drawn into the engine through the front intake. The compressor squeezes the air to many times normal atmospheric pressure and forces it into the combustor. Here, fuel is sprayed into the compressed air, is ignited and burned continuously like a blowtorch. The burning gases expand rapidly rearward and pass through the turbine. The turbine extracts energy from the expanding gases to drive the compressor, which intakes more air. After leaving the turbine, the hot gases exit at the rear of the engine, giving the aircraft its forward push ... action, reaction.

For additional thrust or power, an afterburner can be added. Additional fuel is introduced into the hot exhaust and burned with a resultant increase of up to 50 percent in engine thrust by way of even higher velocity and more push.

Turboprop Engines

A turboprop engine is a jet engine attached to a propeller. The turbine at the back is turned by the hot gases, and this turns a shaft that drives the propeller. Some small airliners and transport aircrafts are powered by turboprops.

Like the turbojet, the turboprop engine consists of a compressor, combustion chamber, and turbine, the air and gas pressure is used to run the turbine, which then creates power to drive the compressor. Compared with a turbojet engine, the turboprop has better propulsion efficiency at flight speeds below about 500 miles per hour. Modern turboprop engines are equipped with propellers that have a smaller diameter but a larger number of blades for efficient operation at much higher flight speeds. To accommodate the higher flight speeds, the blades are scimitar-shaped⁶⁵ with swept-back leading edges at the blade tips.

The RD-33 turbojet twin-shaft engine

The RD-33 turbojet twin-shaft engine with afterburner was developed in 1985 to power the MiG-29 front-line light fighter.

Engineering excellence

The engine features a modular design, which means that individual parts, units and modules can be repaired or replaced in the field.

Reliability

The RD-33’s excellent gas flow stability against ambient disturbances, including the firing of onboard weapons, dramatically facilitates control of the aircraft. These engines also offer a high rate of thrust increase and, therefore, aircraft acceleration, which is especially critical for today’s jet fighters.

Universal platform

The RD-33 engine family includes the following versions:

RD-33 series 3, an engine with a longer service life;

RD-33B / NB, an engine without the afterburner for various types of aircraft;

SMR-95, an engine for upgrading foreign 2nd and 3rd generation jet fighters;

RD-93, a version for the FC-1 airplane;

RD-33MK (Sea Wasp), an improved version of RD-33 for new MiG-35 jet fighters and MiG29K ship borne fighters.

An RD-33 version with a thrust vectoring nozzle (TVN) is also available. New engines of the RD-33 family include BARK digital monitoring and control systems. Repair and maintenance of RD-33 engines take advantage of an information and diagnostics system (IDS).

Facts

The most mass-produced jet engine in its class

Adopted by the military in 25 countries as a component of MiG-29 fighters

Employed to power the unique super-maneuverable MiG-29OVT fighter

Installed of various models of the MiG-29 fighter family

Developed in 1985

Thrust class – 8000-9000 kgf

Principal specifications of RD-33:

Full afterburning performance (H=0, М=0):

thrust, kgf…………………………………………………………...8300

Maximum performance without afterburning (H=0, М=0):

thrust, kgf…………………………………………………………...5040

Length, mm…………………………………………………………4230

Maximum diameter, mm………………………………………........1040

Weight, kg…………………………………………………………..1055

Range and fuel system

The internal fuel capacity of the original MiG-29B is only 4,365 liters distributed between six fuel tanks, four in the fuselage and one in each wing. As a result, the aircraft has a very limited range, in line with the original Soviet requirements for a point-defense fighter. For longer flights, this can be supplemented by a 1,500 liter (330 Imp gal, 395 USgal) centerline drop tank and, on later production batches, two 1,150 liter (365 Imp gal, 300 USgal) under wing drop tanks. In addition, a small number have been fitted with port-side in-flight refueling probes, allowing much longer flight times by using a probe-and-drogue system. Some MiG-29B airframes have been upgraded to the «Fatback» configuration (MiG-29 9-13), which adds a dorsal-mounted internal fuel tank.

Operational history

The Soviet Union exported MiG-29s to several developing countries. Because 4th-generation fighter jets require the pilots to have extensive training, air-defense infrastructure, and constant maintenance and upgrade, MiG-29s have had mixed operational history with different air forces. For example, while the MiG-29s have an excellent operational history under the Indian Air Force which has invested heavily in the aircraft, it does not however have a good track record while serving the air forces of other countries like Iraq and Yugoslavia.

TV3-117VMA-SBM

The engine is designed for the An-140 airplane and other high-efficiency passenger and cargo aircraft of regional airlines. High-tech development and production have enabled to create the TVS

117VMA-SBM1 engine possess superior operating performance, dependability, and extensive service life.

Main advantages:

• high efficiency;

• long service life;

• reliability and trouble-free operation;

• engine and propeller joint electronic control system;

• two emergency power conditions making it possible to take off and maintain a flight level with one engine inoperative;

• low-emission combustor;

• low noise level;

• low operating costs.

Turbofan Engines

A turbofan engine has a large fan at the front, which sucks in air. Most of the air flows around the outside of the engine, making it quieter and giving more thrust at low speeds. Most of today’s airliners are powered by turbofans. In a turbojet all the air entering the intake passes through the gas generator, which is composed of the compressor, combustion chamber, and turbine. In a turbofan engine only a portion of the incoming air goes into the combustion chamber. The remainder passes through a fan, or low-pressure compressor, and is ejected directly as a «cold» jet or mixed with the gas-generator exhaust to produce a «hot» jet. The objective of this sort of bypass system is to increase thrust without increasing fuel consumption. It achieves this by increasing the total air-mass flow and reducing the velocity within the same total energy supply.

D-18T

The D-18T is used to power the An-124 RUSLAN and An-225 MRIYA cargo aircraft. The engine is equipped with an efficient thrust reverser mounted in fan duct. The engine’s module design together with efficient component condition diagnostics means provides possibility of on-condition operation without plant overhauls.

Main advantages:

• Low specific fuel consumption;

• Low noise and pollutant emission levels (comply with ICAO standards);

• High maintainability and reparability.

The D-436T1 / T2

The D-436T1/T2 engine is intended to power short-haul and medium-haul airliners Tu-334-100, Tu-334-200, Tu-230 and other highly efficient passenger and cargo aircraft. The engine complies with both effective and future ICAO requirements for aircraft engine noise and emission performances.

Main advantages:

• Low specific fuel consumption and low weight-to thrust ratio;

• High reliability due to long experience in operating the D-36 engine of similar class;

• Low levels of emission and noise;

• Easy maintenance and high affectivity of monitoring and diagnostics system;

• Universal mount for installing the engine on various airplanes in under wing or over wing, fuselage or side positions without changing the engine design;

• Low operating costs at long service life.