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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/Tipjet7/30/2019 Testing Model 2
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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