Testing Model 2

7/30/2019 Testing Model 2

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UNIVERSITY OF PETROLEUM AND ENERGY STUDIES

Design and fabrication of VTOL engine

Minor Project by

Chava YPDP RajinishR180208013

Mayank JuyalR180208022

Ved PrakashR180208044

Chetan SonkerR180208049

Project Supervisor: Dr. Ugur Guven

Department: ASE

Program: Aerospace engineering


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FOREWORD

We would like to express our deep appreciation and thanks for our advisor. This work is

supported by Dr. Ugur Guven.

16th November 2010 Thesis Author: Dr. Ugur Guven

Aerospace Engineer


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TABLE OF CONTENTS

Page

TABLE OF CONTENT3

ABBREVIATION .4LIST OF FIGURES..5

SUMMARY ...6

1 Introduction .7

1.1 History of VTOL.7

1.2 Types of mechanism in VTOL...9

1.2.1 Tilt rotor mechanism.10

1.2.2 Vector thrusting .10

1.3 Need of VTOL 11

1.4 What VTOL aircraft should possess.12

1.5 Why VTOL is preferred12

2 Jet engines 13

2.1 Jet Engines ...13

2.2 What jet engine does.......................................................................14

2.3 History of Jet Engines.14

2.4 Components of a jet engine.15

2.5 Jet engine types15

2.5.1 Turbojet...15

2.5.2 Turbofan .16

2.5.3 Turboprop ..162.5.4 Turbo shaft..17

2.5.5 RAM jet17

2.5.6 SCRAM jet...18

2.6 Thrust and thrust equation.18

2.7 Efficiency ..19

2.7.1 Thermal efficiency..19

2.7.2 Propeller efficiency 20

2.7.3 Transmission efficiency .20

2.7.4 Propulsive efficiency...20

2.7.5 Overall efficiency21


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ABBREVIATION

VTOL : Vertical takeoff and landing

VTVL : Vertical takeoff with vertical landing

STOL : Short takeoff and landing

CTOL : Conventional takeoff and landing

STOVL : Short takeoff and vertical landing

V/STOL : Vertical/Short takeoff and landing

SCRAM Jet : Supersonic combustion RAM jet


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LIST OF FIGURES page

Figure 1.1: VTOL in vertical flight...9

Figure 1.2: Vanguard Omni plane with tilt rotor mechanism...10

Figure 1.3: Yak 36 with Vector thrusting.11

Figure 2.1: Idealized brayton cycle...13

Figure 2.2: Turbo jet engines.15

Figure 2.3: Turbofan.16

Figure 2.4: Turbo prop ..16

Figure 2.5: Turbo shaft.17

Figure 2.6: Ram jet...17

Figure 2.7: SCRAM JET..18

Figure 2.8: schematic diagram of propulsive device18


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DESIGN AND FABRICATION OF VTOL AIRCRAFT

ABSTRACT:

VTOL is an abbreviation for vertical take-off and landing. There are two methods for v-tol

technology, namely tiltrotor mechanism and vector thrusting. We wish to design an aircraft

using tiltrotor mechanism. Since, it has many disadvantages like its complicated mechanism and

its less efficiency we want to design, such an aircraft whose efficiency is higher and with simpler

mechanisms in its design.

We intend to study the flow characteristics over various designs using various softwares and

fabricate the best possible design overcoming the disadvantages mentioned above.


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1 Introduction:

1.1 VTOL:

VTOL stands for vertical takeoff and landing. As the name suggest the aircraft with this type of

technology doesnt need any runway. It doesnt create lift with the help of flaps and other control

surfaces here the thrust is generated in vertical direction which is responsible for lifting up the

aircraft. This thrust is achieved by two methods first is by tilt rotor mechanism which is used in

V 22 osprey series and the other one is Vector thrusting which is in Harrier aircraft.

Generally they are fixed wing aircraft that can hover take off and land vertically. Helicopters and

other aircrafts powered with rotors, say tilt rotors, balloon, rockets etc. comes under this

category.

Balloons are similar to these but they are termed as VTVL. These VTOL can be operated in

some other modes also such as CTOL, STOL, and STOVL. Helicopters can operate by VTOL

due to the aircraft lacking landing gear that can handle horizontal motion.

The first practical VTOL was the Hawker Siddeley Harrier, introduced in 1969. It was one of

several successes among numerous failed efforts to develop VTOL craft that were pursued in the

60s. The motivation behind creating VTOL is to produce a craft capable of vertical takeoff, like a

helicopter, while retaining the desirable features of fixed-wing aircraft, such as high cruise

speeds. Indeed, the VTOL-equipped French Dassault Mirage IIIV achieved speeds of Mach 1.32

during testing.

1.2 History of VTOL:

In the year 1947 both U.S.A Air force and U.S.A Navy had sponsored VTOL design studies

called the Project Hummingbird. The rapid development of increasingly power plants had

reached the point where a true VTOL aircraft was in possibility. The XFV 1 was the first one

which had convoy-fighters YT 40 gas blade engine dove a six bladed, counter rotating Curtiss

propeller designed specifically for hovering flight. This gave the airplane a thrust to weight ratiogreater than one enabling it to hover and take off and land vertically.

Many engineers worked for Soviet Union for this purpose. First one was K.V. Shoolikov; he was

the one who gave an idea of this vector thrusting and his concept of movable nozzle was used in

Bell X-14.

On January 3, 1928 Nicola tesla patented a design and it was termed as Tesla's VTOL patent

(U.S. Patent 1,655,113) in this he described a method of achieved vertical take-off, transition to


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and from horizontal flight, and vertical landing, with a tilting rotor. In addition to the helicopter,

many approaches have been tried to develop practical aircraft with vertical take-off and landing

capabilities. An early contribution to VTOL was Rolls-Royce's Thrust Measuring Rig ("flyingbedstead") of 1953. This led to the first VTOL engines as used in the first British VTOL aircraft,

the Short SC.1 (1957) which used 4 vertical lift engines with a horizontal one for forward thrust.

Another British VTOL project was the gyrodyne, where a rotor is powered during take-off and

landing but which then freewheels during flight, with separate propulsion engines providing

forward thrust. Starting with the Fairey Gyro dyne, this type of aircraft later evolved into the

much larger twin-engined Fairey Rotodyne, that used tipjets to power the rotor on take-off and

landing but which then used two Napier Eland turboprops driving conventional propellers

mounted on substantial wings to provide propulsion, the wings serving to unload the rotor during

horizontal flight. The Rotodyne was developed to combine the efficiency of a fixed-wing aircraft

at cruise with the VTOL capability of a helicopter to provide short haul airliner service from city

centres to airports.

The use of vertical fans driven by engines was investigated in the 1950s. The US built an aircraft

where the jet exhaust drove the fans, while British projects not built included fans driven bymechanical drives from the jet engines.

The idea of using the same engine for vertical and horizontal flight by altering the path of the

thrust led to the Bristol Siddeley Pegasus engine which used rotating ducts to direct thrust over a

range of angles. This was developed side by side with an airframe, the Hawker P.1127, which

became subsequently the Kestrel and then entered production as the Hawker Siddeley Harrier,though the supersonic Hawker Siddeley P.1154 was canceled in 1965. The French in competition

with the P.1154 had developed a version of the Dassault Mirage III capable of attaining Mach 1.The Dassault Mirage IIIV achieved transition from vertical to horizontal flight in March 1966,reaching Mach 1.3 in level flight a short time later.

The Harrier is often flown in STOVL mode which enables it to carry a higher fuel or weapon

load over a given distance. Now retired from British Royal Navy service, the Indian Navy

operates Sea Harriers mainly from its aircraft carrier INS Viraat. The latest version of theHarrier, the BAE Harrier II is operated by the British Royal Air Force and Royal Navy. The

United States Marine Corps, and the Italian and Spanish Navies use the AV-8B Harrier II, an

equivalent derivative of the Harrier II. The Harrier II/AV-8 will be replaced in the air arms of the

US and UK by a STOVL variant of the F-35 Lightning II.

NASA has flown other VTOL craft such as the Bell XV-15 research craft (1977), as have theSoviet Navy and Luftwaffe. Sikorsky tested an aircraft dubbed the X-Wing, which took off in the

manner of a helicopter. The rotors would become stationary in mid-flight, and function as wings,

providing lift in addition to the static wings. Boeing X-50 is a Canard Rotor/Wing prototype thatutilizes a similar concept.

The Yakovlev Yak-38 was the Soviet Navy's VTOL aircraft for their light carriers, cargos hips,

and capital ships. It was developed from the Yakovlev Yak-36 experimental aircraft. Before the
http://en.wikipedia.org/wiki/Tipjethttp://en.wikipedia.org/wiki/Napier_Elandhttp://en.wikipedia.org/wiki/Turboprophttp://en.wikipedia.org/wiki/Turboprophttp://en.wikipedia.org/wiki/Napier_Elandhttp://en.wikipedia.org/wiki/Tipjet


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Soviet Union collapsed, a supersonic VTOL aircraft was developed as the Yak-38's successor,

the Yak-141, which never went into production.

A German V/STOL VJ101 on display at the Deutsches Museum, Munich, Germany In the 1960s

and early 70s Germany planned three different VTOL planes. One used the F-104 as a base forresearch for a V/STOL aircraft. Although two models (X1 and X2) were built, the project was

canceled due to high costs and political problems as well as changed needs in the Luftwaffe and

NATO. The EWR VJ 101C did perform free VTOL take-offs and landings, as well as test flightsbeyond mach 1 in the mid- and late 60s. One of the test-aircraft is preserved in the Deutsches

Museum in Munich, Germany. The others were the VFW-Fokker VAK 191B light fighter and

reconnaissance plane, and the Dornier Do 31E-3 (troop) transport.

Fig 1.1 VTOL in vertical flight


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1.3 Types of mechanism for VTOL

There are two methods by which an aircraft is lifted vertically, they are tilt rotor mechanism and

vector thrusting.

1.3.1 Tilt Rotor Mechanism:

It is an aircraft which have a couple of more powered rotors (prop rotors) mounted on a rotating

shaft at the end of fixed wing. For vertical flight the rotors are angled so the plane of rotation is

horizontal. As the velocity of the aircraft is increased the rotors are tilted forward, with the plane

of rotation in vertical direction. In this mode lift is provided by wings and the rotors give thrust.

The wings efficiency helps tilt rotor to achieve higher speeds than helicopters. Examples of the

aircraft with this technology are as follows:

Bell XV-3

Curtiss- Wright X-19Bell X-22

Aerospatiale N 500

Bell Eagle eye

Bell/Augusta BA609

Fig. 1.2 Vanguard Omni plane with tilt rotor mechanism

1.3.2 Vector Thrusting:


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Aircrafts having this technology are able to manipulate the direction of the thrust from engines in

order to control the angular velocity. Initially it was developed to provide vertical thrust but now

this technique is used in many fighter aircrafts in combat situations in order to perform various

maneuvers.

This is generally used in Rockets, Missiles etc.Examples of Aircrafts using vector thrusting are as follows:-

Bell Boeing V-22 Osprey

Boeing X-32

Yakovlev Yak-38

Yakovlev Yak-141

Lockheed Martin F- 35 B Lightning II

Harrier Jumpjet

Dornier Do 31

Fig. 1.3 Yak 36 with Vector thrusting

1.4 Need of VTOL:

During 1950s there was a demand by navy to have aircrafts that can takeoff from ship so they

wanted aircrafts with STOL or VTOL capability so that they can take off from the deck of the

ship with high cruising speed. These types of aircrafts have very high maneuvering capability

due to its thrust vectoring feature. The need for a versatile VTOL aircraft is ever increasing in


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our world was natural and man-made disasters are a seemingly everyday occurrence. The

capabilities of a rapid response, long-range aircraft could save thousands more lives than is

possible with todays means. The need for such an aircraft will only continue to rise, as fishing

boats travel further for their catches, more commercial vessels cross the seas, and more pleasure

boats set out to explore the open ocean. Further advancements of this design could be explored

as well. Smaller versions may be adaptable to the general aviation market. Such aircraft could

truly usher-in the era of flying cars. Not only would such an aircraft revive the general aviation

community, it would also improve the domestic economy if all manufacturing was to be done at

one of the current U.S light plane manufacturers (i.e. Piper, Beech craft and Cessna). All

branches of aviation could explore the benefits of this aircraft. Civil, commercial, and military

aviation could all make use of an aircraft capable of heavy lifting, forest fighting, and operating

out of any open field. In hindsight, an aircraft with these capabilities could have been used to

save lives in many recent disasters. In the collapse of the World Trade Centers, they could have

preformed roof top rescues, they could have quickly responded to victims in distress during

hurricane Katrina, or they could have provided immediate aid to earthquake victims in Haiti orChile. An aircraft with these capabilities could change the way search and rescues are carried out

worldwide.

1.5 What VTOL aircraft should posses?

A Stable design.

Thrust to Weight ratio must be greater than one.

It should be stable while hovering and at low speed.

Conventional control Surfaces are useless due to insufficient dynamic pressure.

1.6 Why VTOL is preferred:

It needs very short runway and hanger which reduces the cost of runway.

It does not need conventional control surfaces which reduces the cost of the Airplane.

VTOL aircrafts have high maneuvering ability.

Take off is very easy and low risk is there.


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Chapter2 Jet engines:

2.1 Jet engines:

After developing I.C. (internal combustion) engines we wanted to go faster, we wanted to cross

the barrier of sound. This job was not easy; it was not even possible with the I.C. engines as there

are many losses inside the engine. So to cross the sound barrier a new concept of jet engine came

into picture. Jet engines were totally different with the I.C. engine (piston engine). Here

combustion takes place at some other place and utilized at the place where it is needed. With

help of this technology only we were able to fly jumbo jets like airbus A380.

So a jet engine is a reaction engine that discharges a fast moving fluid to generate thrust

according to newtons law of motion. There are different types of jet engines they are turbo jet,

turbo prop, Ramjet, Scramjet etc. We have different components in this type of engine they are,

diffuser, compressor combustion chamber, turbines and at last nozzle.

2.2 What jet engine does?

It sucks air from the surrounding with the help of a propeller or fan. After that there is a diffuser

which increases the pressure of the inlet air as the pressure is increased velocity of air reduces.After that we have compressor which compresses the air and then passes it to the combustion

chamber. There the fuel is injected with the help of nozzles and then air and fuel mixture is

prepared which is then ignited with the help of battery. After burning the velocity of air is

increased then it is passed through turbine which is connected to the compressor with the help of

which compressor is rotated. Then we have a nozzle which increases the velocity of the out

coming air and the air which is coming out has a velocity much greater then inlet velocity.

The jet engine works on Brayton cycle. It is a thermodynamic cycle that describes the workings

of gas turbine engine. The cycle is shown in the figure.


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Fig. 2.1 Idealized Brayton Cycle

2.3 History of Jet Engines:

Sir Isaac Newton in the 18th century was the first to theorize that a rearward-channeled

explosion could propel a machine forward at a great rate of speed. This theory was based on his

third law of motion. As the hot air blasts backwards through the nozzle the plane moves forward.

Henri Giffard built an airship which was powered by the first aircraft engine, a three-horsepower steam engine. It was very heavy, too heavy to fly.

In 1874, Felix de Temple, built a monoplane that flew just a short hop down a hill with the help

of a coal fired steam engine.

Otto Daimler, in the late 1800's invented the first gasoline engine.

In 1894, American Hiram Maxim tried to power his triple biplane with two coal fired steam

engines. It only flew for a few seconds. The early steam engines were powered by heated coaland were generally much too heavy for flight.

American Samuel Langley made model airplanes that were powered by steam engines. In 1896,

he was successful in flying an unmanned airplane with a steam-powered engine, called the

Aerodrome. It flew about 1 mile before it ran out of steam. He then tried to build a full sizedplane, the Aerodrome A, with a gas powered engine. In 1903, it crashed immediately after beinglaunched from a house boat.

In 1903, the Wright Brothers flew, The Flyer, with a 12 horse power gas powered engine. From

1903, the year of the Wright Brothers first flight, to the late 1930s the gas powered reciprocating

internal-combustion engine with a propeller was the sole means used to propel aircraft.

It was Frank Whittle, a British pilot, who designed the first turbo jet engine in 1930. The first

Whittle engine successfully flew in April, 1937. This engine featured a multistage compressor,

and a combustion chamber, a single stage turbine and a nozzle.

The first jet airplane to successfully use this type of engine was the German Heinkel He 178. Itwas the world's first turbojet powered flight. General Electric for the US Army Air Force built

the first American jet plane. It was the XP-59A experimental aircraft.


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2.4 Components of a jet engine:

Compressor:

This is a type of fan with blades connected to the turbine with a shaft. It squeezes the

incoming air into smaller areas, resulting in an increase in the air pressure. This increases

the potential energy of the air. This compressed air is entered into combustion chamber.

Combustor:

Here the air ismixed with fuel and then ignited with the help of a battery. There are more

than 20 nozzles to spray the fuel into the air stream. When the fuel is ignited very high

temperature is produced which gives high energy as the gases will expand. The material

used to make this is ceramics as the temperature inside the combustion chamber is about

2700oC

Turbine:

The high energy flow coming out from the combustion chamber goes into the turbine,

which makes it to rotate. This is connected to compressor with the help of a shaft.Nozzle

This is the part which actually produces thrust for the plane. The energy less flow that

came through turbine, and also the flow which bypassed the engine core, produces a force

when exiting the nozzle which propels the engine and by Newtons third law of motion

we have a forward motion of the aircraft. It may be preceded by a mixer, which combines

the high temperature air coming from the engine core with the lower temperature air that

was by passed in the fan.

2.5 Jet engine types:

Under this category we have different types of engines they are as follows:

2.5.1 Turbo jet:

It compresses the air with the help of inlet and a compressor. The fuel mixes with air and then it

is ignited with the help of a battery. After that a turbine is there which is connected with the help

of a shaft to compressor.

Fig. 2.2 Turbo jet engines


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2.5.2 Turbo fan:

It is a gas turbine engine which is very similar to turbojet. All the functions of turbo fan are

similar to turbo jet but the difference is that they have an extra fan to suck air and it is also

powered by the turbine section. Unlike turbo jet some of the flow accelerated by fan bypasses the

generator core of the engine and is exhausted through a nozzle. The bypassed flow is at lower

velocities, but a higher mass, making thrust produced by the fan more efficient than thrust

produced by the core.

There are two types of jet engine characterized according to the bypass ratio they are low bypass

and high by pass. Turbo fan are more efficient than turbojet but it has large frontal area which

causes large drag.

Fig. 2.3 Turbo fan engine

2.5.3 Turbo prop:

This is the engine with very high by pass ratio, it is similar to turbo fan but the difference is that

it doesnt have any fan it uses a propeller. Here thrust is generated by the spinning of the

propeller. They have better performance than turbo jets at low speed as propeller efficiency is

high here. But at high velocity its not as good as turbo fan.

Fig. 2.4 turbo prop engine


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2.5.4 Turbo Shaft:

This is another type of jet engine which is similar to turboprop. It is generally used in

helicopters. It is designed in such a way that the speed of the helicopter rotor is independent of

the speed of generator. This keeps the rotor speed to be constant even when the speed of

generator is varied.

Fig. 2.5 Turbo shaft engine

2.5.5 Ram Jet:

They are similar to turbo jet engine as they also work on brayton cycle but the difference is that

there they were using compressor to compress the incoming air but in ram jet engine we do not

have compressor, since compressor is not there, there is no need of turbines. It has no

compressor so to compress the incoming air it uses a new technique ramming. In this shock

waves are created both type of shock waves are there normal and oblique, oblique at the entranceand normal inside the engine rest all the function is same.

Fig. 2.6 Ramjet engine

Shock waves are created with the help of needle like structure as shown in the figure. There is a

disadvantage with this type as it operates at high velocity only.


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2.5.6 SCRAM Jet:

This Is Supersonic combustion Ramjet, here the combustion takes place at supersonic air speed.

Hence it is termed as supersonic combustion Ram jet. All its features are derived from Ram jet,

but here the ramming is more. And that is due to the chain of normal shock.

Fig. 2.7 Scramjet engine

2.6 Thrust and Thrust Equation:

Let us consider the control volume of a schematic propulsive device as shown in the figure.

A mass i of air enters the control volume with a velocity ci and pressure pi and the products of

combustion of mass j leaves the control volume with velocity cj and pressure pj. the flow is

assumed to be steady and reversible outside the entire control volume, the pressureand velocity

being constant over the control volume except that at the exhaust area Aj. force F is the force

necessary to balance the thrust produced due to change in momentum of the fluid as it passes

through the control volume.

Fig.2.8 schematic diagram of propulsive device

If pa is the atmospheric pressure, then momentum equation is


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Equation 2.1

or thrust,

Equation 2.2

we have by mass balance,

Equation 2.3

where are the mass flow rates of exhaust gases, air, and fuel respectively.

If

f = fuel air ratio = Equation 2.4

(1 + f) Equation 2.5

Equation 2.6

from the above equation it is clear that the net thrust produced is made up of two parts, viz.

momentum thrust and pressure thrust. If the exhaust velocity cj from the control volume is sub

sonic then pj pa. also pi pa. so that pressure thrust is quite small.

For supersonic exhaust velocity the pressure pj may differ from pa. However the pressure thrustdeveloped is so small as compared to the momentum thrust that it can safely be neglected for

simple calculations and the net thrust is given by

Equation 2.7

2.7 Efficiency

The overall efficiency o of a propulsive device is the ratio of the useful work done to the

chemical energy supplied in the form of fuel.

2.7.1 Thermal efficiency:

Thermal efficiency of a propulsive device is an indication of the degree of utilization of energy

in fuel in accelerating the fluid flow and is defined as the ratio of propulsive power furnished to

exhaust nozzle to the heat supplied and is given by


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Equation 2.8

Equation 2.9

Where Qi = f CV = heat supplied to the engine per kg of air and f is fuel air ratio and CV is the

calorific value of the fuel.

2.7.2 Propeller efficiency:

The propeller produces thrust power by accelerating the air. The propeller itself is driven by the

engine. The efficiency of the propeller is defined as the ratio of the thrust power to the shaft

power.

= Equation 2.10

2.7.3 Transmission efficiency:

The turbine output cannot be directly applied to the propeller some form of transmission is

involved between the engine and the propeller in the form of a reduction gear. The main reason

for providing reduction gear in the case of turboprop engine is high rotational speed of the

turbine at which the propeller cannot be rotated efficiently. In addition to this some layout

problems always occur. Due to friction and other losses the output from the transmission systemis always less than input to it and the transmission efficiency is defined as

Equation 2.11

2.7.4 Propulsive efficiency:

During the forward motion, the specific thrust, cj, is reduced by the inlet drag ci. The net thrust

thus, is dependent not only on the power plant but also on the flight speed. Its utilization is in

terms of propulsive efficiency.

So it is the measure of the effectiveness with which the kinetic energy imparted to the fluid is

transferred into useful work.

Equation 2.12

Thrust power = F*ci


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Propulsive power = ma(1+f)cj2/2ma ci

2/2

Equation 2.13

2.7.5 Overall efficiency:

The performance of the propulsion system is normally evaluated in terms of overall efficiency,

o is defined as the ratio of rate at which useful propulsion work is done to the rate at which

energy is supplied to the system. In other words the overall efficiency o of a propulsive device is

the ratio of the useful work done to the chemical energy supplied in the form of fuel.

o

=

=

= Thermal efficiency* Transmission efficiency* Propulsive efficiency

=th*tr*p Equatiion 2.14

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