AERONAUTICAL LECTURING NOTES

What is gas turbine engine? A gas turbine is a machine delivering mechanical power or thrust. It does this using a gaseous working fluid which is continuously flowing. This working fluid is initially compressed in the compressor. It is then heated in the combustion chamber by chemical reaction. Note: lot of energy has been added to working fluid at this stage. Finally, it goes through the turbine. The turbine converts the energy of the gas into mechanical work. Part of this work is used to drive the compressor. What are the types of compressor used in gas turbine engines? Centrifugal Compressor Axial flow compressor Just name any three aircraft power-plant makers? General Electric Rolls Royce Pratt & Whitney

What is meant by I.C. engine? In this type of engine, combustion of fuel takes place within the cylinder. This type of engine includes gas engine, petrol engines and diesel engines. These are generally used for road vehicles, locomotives, and aircraft and for other industrial applications. Write the classification of I.C. engines. Based on ignition: Spark ignition Compression ignition Based on fuel: Petrol engine Diesel engine Based on cooling system: Air cooled   Water cooled  What is reciprocating engine?  An engine in which reciprocating motion of piston creates mechanical    energy, necessary to do a work.    What are the types of fuel ignition in reciprocating engine?    Spark ignition- Uses a spark plug to ignite fuel   Compression ignition- Compression will be done excessively so that when       fuel enters it can automatically ignite.     Note: Whenever we do compr...

Write down all type of power plants that are being used in aircrafts? Reciprocating engines Gas turbine engine Ramjet engine Scramjet engine What are the types of gas turbine engines? Turbo jet Turbo prop Tubo fan Turbo shaft Which gas turbine engine is fuel efficient? Turbo fan What are the components of Turbojet engine? Inlet Compressor Combustion chamber Tubine Nozzle Exhaust  Write the advantages of gas turbine power plants. The capital cost of plant is low. This can be quickly commissioned. It requires less space. Capacity to use wide variety of fuels Write the disadvantages of gas turbine power plants About two third of the power developed by the turbine is used to drive the compressor. Hence net output of plant is low. Low efficiency Needs special cooling arrangements Operating temperature is high of the order of 20000C.

What are the types of rockets? Based on the fuel (Propellant) type used Solid Propellant Liquid propellant Hybrid Electric rocket Ionic rocket What is missile? Missile is same like a rocket. The purpose of use is to destroy enemies. Missile will be launched in inclined position with reference to earth horizon. In what way does a rocket differ from aircraft? Rocket is operating in space where no air (No oxygen for  combustion ) is available and also in the air. So in order to have an efficient thrust from combustion it needs to have separate tank for oxygen storage. But aircraft since it is operating in air; it has air breathing engines. 

What is helicopter? Rotary wing aircraft with engine or engines (heavier than air) which can sustain in flight (within atmosphere), because of the lift produced by its rotary wings. What is the major difference between Aircraft to rotor craft? Aircraft needs runway to take-off and land whereas a rotor craft can take off and land without runway. What is spacecraft? A Fixed wing heavier than air aircraft, with engine, which can fly in space because of thrust. What is rocket? Rocket is a flying object which is operating on atmosphere as well as in space because of thrust developed by its engines.

   What is engineering? Engineering is the combination of Science and mathematics to serve for human needs. It has many divisions. Some are aerospace, computer science, civil, Electrical, Mechanical etc. Who is an Engineer? Engineers understand what people needs and design them, construct it or machine it, maintain it. Also they will have a look on cost, quality and timing. Engineer creates an object which is not present with the help of science and mathematics. What is aeronautical engineering? Understanding the concept of flying within the atmosphere, developing/creating flying objects by engineering ideas. What is aerospace engineering? Understanding the concept of flying in space as well as in atmosphere, with that knowledge they may able to design a spacecraft, rocket or they may work in space.

What are the layers of atmosphere? Troposphere- 0 to 10 Kms Stratosphere- 11 to 50 Kms Mesosphere-50 to 80 Kms Ionosphere-80 to 500 Kms Exosphere-500 to Infinity Kms What are the axes of an aircraft? Longitudinal Axis- Along the length of the fuselage Lateral axis- Along the length of wing span Normal axis- Mutually perpendicular to the above two axis What are the moments occuring with reference to those axes? Longitudinal axis- Rolling Lateral axis- Pitching moment Normal axis- yawing

What are the major parts of an aircraft? Main wing Tail wing Powerplant Fuselage Landing gear What is the reason for stall? Define critical angle of attack? If the angle of attack for an aerofoil increases from zero deg, you can watch the increase in lift and drag. If you keep on increasing the AOA, at some point sudden loss of aerodynamic forces will occur. Aerofoil can create aerodynamic forces in a large magnitude when attached flow of air occurs at aerofoil surface.  As the aerofoil gets increased AOA, the flow of air starts detaching from the aerofoil surface. If fully detached then no aerodynamic forces will be generated. That is what the reason for stall. The angle at which stalling starts is the critical angle of attack. What is stagnation point? Stagnation point is the point in the airflow where the velocity gets its zero magnitude because of the presence of object in airflow. The flow deviates/joins between upper and lower surface of the ...

What are the phases of flight? Takeoff Climb Cruise Descent Loiter Landing What is aerodynamic centre? Aerodynamic center is the point in the aerofoil where the pitching moment is constant even though if we change angle of attack. To solve flight dynamics problem it is the pivotal point. What is center of pressure? Centre of pressure is the point where the pitching moment is zero. When angle of attack varies cop varies. So it is tedious if we try to solve dynamics of flight by taking COP as reference.

What is parafoil? A leading edge opened aerofoil is called as “Parafoil”. We know already that leading edge is facing into the wind for aerofoil. Since it has been opened, it just admits the air to flow inside the volume covered by the upper and lower surfaces. How aerofoil creates lift? What is bernouli's principle? How it suits to the aerofoil? Aerofoil has its upper surface curved, whereas bottom is moreover flat. Physically the curved portion accelerates the flow and so the top side airflow is getting increase in velocity. Lower surface is experiencing less velocity when comparing the upper surface. We know from Bernoulis law that for a fluid flow, if fluid velocity increases then pressure drops. In the upper we are feeling less pressure and in the bottom a high one. Bernoulis principle: Total energy of a steady flowing fluid system is constant. Ʃ E= k PE+KE= k mgh+0.5 mv 2 =k dividing both sides by volume ρgh+ 0.5ρv 2 =k High p...

What is aerodynamics? Aerodynamics is the study about the object moving in airflow. Here we will pay our attention to the airflow and also to the object immersed in the airflow. What is aerofoil? If you throw a pencil in air, you see, it flies and comes down instantly. So it is also having ability to fly. Technically speaking, every object is having some figures called Coefficient of lift, Coefficient of drag which governs its motion during flight. The shape which has more coefficient of lift and less coefficient of drag can stay in fly for more. Such a shape is what aerofoil. Aerofoil is having top surface (Upper camber) and lower surface (lower camber). Also it has leading edge and trailing edge where the two surfaces meet. Leading edge is facing to the wind. What is chord line? A line joining the leading edge of an aerofoil to the Trailing edge is known as Chord line. What is camber line? We know that aerofoil is having top surface (upper camber)and bot...

Who introduced the flying concepts? Leonarda Da vinci Drawn aerofoil- ornithopter. He might have developed physical prototype. But still now there is no evidence that Da vinci had fly. But his inventions formed the basics of flight. Who made first successful flight? Wright brothers on 1903. What is aircraft? Aircraft is an object which is able to fly. What is airplane? Fixed wing aircraft with engine or engines (Heavier than air) which can fly in atmosphere because of aerodynamic forces generated by its wings.

What do you mean by equilibrium? Equilibrium is a state of rest of a body. Equilibrium equations also include the body moving with zero acceleration (uniform velocity) along a straight line. What is motion? When it will occur? Motion is change of position of a body with respect to time. To have a motion in any direction, the body should have an unbalanced force in the same direction. What is scalar? Give some examples Scalar is a physical quantity that contains only magnitude information. E.g. Mass, Time What is vector? Give some examples Vector is a physical quantity that contains both magnitude and direction information. E.g. Weight, Distance

What is Inertia? Inertia is a property of object through which it resists any change in its state. The  inability of a body to  change its state of rest or of uniform  motion by itself is called inertia. Newtons first law is more concerned with inertia and hence it is called as Law of inertia. What is mass? Mass is simply a measure of inertia. That means heavier bodies can resist forces (that are trying to deform its state) easily than a lighter body. The total number of atoms in an object determines the mass of the object. In SI unit mass is referred in Kg. Mass is a scalar. What is time? Time is a measure of duration between successive events occurring. In SI  system  of units time is measured in Seconds. Its a scalar.

What is space? Space is a region that extends in all directions. All bodies are within the space only. What is matter? Matter is any object that occupies some space. In the above illustration earth is a bigger matter. What is Particle? Particle has mass but no dimensions. So we can call a particle as point too.