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ELEMENTS OF AERONAUTICS

UNIT – IAIRCRAFT CONFIGURATIONS

PART - A

1. What are the three types of stabilizing surfaces present in aircraft?

The types of stabilizing surfaces in aircraft are,

Wing,

Horizontal tail,

Vertical tail.

2. What are the three types of control surfaces present in aircraft?

The types of control surfaces in aircraft are,

Aileron,

Rudder,

Elevator.

3. What is the function of Aileron?

The function of aileron in aircraft is to produce rolling in the aircraft. The ailerons

are present in the

wing and both are deflected in the opposite directions to produce roll.

4. What is the function of Rudder?

The function of rudder in aircraft is to produce yawing in aircraft. The rudders are

present in the

Vertical stabilizer.

5. What is the function of Elevator?

The function of elevator in aircraft is to produce pitching in the aircraft. The

elevators are present in

the horizontal tail and both are deflected in the same direction to produce pitch

6. What are the types of aircrafts?

There are two types of aircraft namely,

Power driven,

Non power driven.


7. What are the types of power driven aircraft?

The types of power driven aircrafts are,

Aeroplane,

Rotorcraft,

Ornithopter.

8. What are the types of non power driven aircrafts?

The types of non power driven aircrafts are,

Gliders,

Sailplanes,

Ornithopters.

9. What is the use of flaps in aircraft?

The use of flap in aircraft is to produce high lift during takeoff and high drag during

landing. The flaps are present in the wing. Both the flaps are operated simultaneously

either in upward or downward direction

10. Distinguish between a glider and a sail plane.Glider Sail Plane

1. Glider is a lighter than aircraft whose free flight does not depend on an engine.2. A glider is a non powered aircraft.3. It is not easy to control a glider i.e. all the control is conventional control

1. Plane is a heavier than aircraft whose flight depend on an engine.2. Sail plane is a power driven aircraft.3. It is not so difficult to control the sailplane because it has power control such as autopilot etc.

11. Distinguish between lighter and heavier than aircraft.Heavier than aircraft Lighter than aircraft

1. Heavier than aircraft are aircrafts which drives their lift from aerodynamic forces.2. They are mainly classified into power driven and non-power driven aircraft.

1. Lighter than aircrafts are aircrafts which are supported by buoyancy in air.2. They are mainly classified into balloons and airships.

12. Biplanes:-

An airplane having two wings placed one above the other is called a biplane. It is not used now.Monoplane:-


An airplane with one main supporting surface wing some times divided into two parts by the fuselage is called a monoplane. It is the mostly used airplane.

13. Forces acting on an airplane

* Lift* Drag* Thrust* Weight

PART – B

1. Explain about the various components of airplane and their functions.

Refer “Introduction to Flight” , Page No. 76 – 77.

2. Explain about the types of flight vehicles and their classifications.

Refer “Flight without formula”, Page No. 4.

3. Give a brief history about the history of aircrafts.

Refer “Introduction to Flight”, Chapter 1.

UNIT – IIINTRODUCTION TO PRINCIPLES OF FLIGHT

PART - A

1. What is Lift of wing? The resultant aerodynamic force acting on the wing when resolved along the direction perpendicular to free stream velocity direction is defined as lift of wing.

2. What is Drag of wing? The resultant aerodynamic force acting on the wing when resolved along the direction parallel to free stream velocity direction is defined as drag of wing.

3. What are the different types of drag?The different types of drag are,

Skin friction drag, Pressure drag, Wave drag, Induced drag.

4. What are the physical properties of atmosphere?


The physical properties of atmosphere are, Temperature, Pressure, Density.

5. Describe the Structure Of Atmosphere.The structure of atmosphere includes,

Troposphere, Tropopause, Stratosphere.

6. Give the Temperature- altitude relationship. T = T1 + a (h-h1)T – Temperature.a – Lapse rate (dT/dh).h – Altitude.

7. Give the pressure-altitude relationship for isothermal layer of atmosphere.P/P1 = e –[g0/RT](h-h1)P – Pressure.g0 – acceleration due to gravity.R – gas constant.T –Temperature.h – altitude.

8. Give the Density-altitude relationship for isothermal layer of atmosphere.ρ/ ρ 1 = e –[g0/RT](h-h1)ρ – Density.g0 – acceleration due to gravity.R – gas constant.T –Temperature.h – altitude.

9. Give the pressure-altitude relationship for Gradient layer of atmosphere.P/P1 = (T/T1) – g0/aRP – Pressure.g0 – acceleration due to gravity.R – gas constant.T –Temperature.a - Lapse rate.

10. Give the Density-altitude relationship for Gradient layer of atmosphere.ρ/ ρ 1 = (T/T1) –{(g0 /aR)+1}ρ – Density.g0 – acceleration due to gravity.R – gas constant.


T –Temperature.a - Lapse rate.

11. LiftLift is the vertical motion of the aircraft against the gravity.

Drag (backward force)It is the pressure on the aircraft caused by the blowing air, which pushes the

aircraft behind.

12. Structural members used in a wing

* Wing spar (longitudinal member)

1. Front spar 2. Rear spar.

* Ribs

13. Mach Number

It is used to find the speed of aircraft.

Mach number = (M) = (V/a) = Velocity of object/velocity of sound

14. Primary control surfaces

* Rudder

*Aileron

*Elevator

Secondary control surfaces

Flap

Spoiler

15. Lateral control:-

Lateral control is a rolling about the longitudinal axis. (Aileron)

Longitudinal Control:-

Longitudinal control is pitching about the lateral axis. (Elevator)

Directional Control:-

Control of direction by rudder.

16. Types of landing gear

Retractable, non retractable

Bi-cycle landing gear


Tri-cycle landing gear

Tricycle tail wheel landing gear.

17. Dihedral angle:-

Dihedral angle is the angle made by upward bent wings.

Unheadral angle:-

Unheadral angle is a negative dihedral.

18. Angle of attack (α)

It is the angle between the wind direction and chord line. If the

angle of attack increases lift also increases.

19. Taper ratio

It is the ratio between chord tip and chord root.

20. Types of wing:-

According to the wing placement

*high wing *mid wing * low wing.

Wing plan form:-

*Elliptical *rectangular * Tapered and swept back

21. Trailing Vortices:-

The trailing is also called as tip vortices. The air flows inwards on

upper surfaces and outwards on the lower surface. This is the source of vortices. Winglets

are used to avoid the vortices.

PART – B

. 1. Explain about the structure of atmosphere. Refer “Flight without formula”, Page No. 12 – 17.2. Derive the Pressure, Density, Temperature altitude relationship for isothermal layer of atmosphere. Refer “Introduction to Flight” , Page No. 107 – 109.3. Derive the Pressure, Density, Temperature altitude relationship for gradient layer of atmosphere. Refer “Introduction to Flight” , Page No. 109 – 111.4. Explain about the different types of drag. Refer “Introduction to Flight” , Page No. 302-306, 310-312, 315-319.5. Explain about the evolution of Lift, Drag and Moment.



UNIT – IIIINTRODUCTION TO AERODYNAMICS

PART - A

1. Define Aspect Ratio.Aspect ratio of the wing is defined as the ratio of wing span (b) to its chord length (c). AR = b/c.Also it can be expressed as AR = b2/s s- plan form wing area.

2. Define Wing loading.Wing loading can be defined as the ratio of the weight of the airplane to its plan form wing area. Wing Loading = W/S.W-Weight of airplane S- plan form wing area.

3. Define Mach Number.Mach number is defined as the ratio of the flow velocity to that of the velocity of sound. It is denoted by M. M =V/a. V- Velocity Of Sound. a-Speed of sound.

4. Define Centre Of Pressure.Centre Of Pressure is the location where the resultant of a distributed load effectively acts on the body. It is the point on the body about which the aerodynamic moment is zero.

5. Define Aerodynamic Centre.Aerodynamic Centre in a point of the aerofoil about which the moment will be independent of the angle of attack.

6. Draw a typical lift curve for cambered aerofoil.


7. Draw the lift curve for symmetrical aerofoil.

8. Draw the drag curve for a typical aerofoil.

9. What are the aerodynamic forces acting on aircraft?The basic aerodynamic forces acting on the aircraft are,

Lift,

Drag,

Thrust,

Weight.


10. What are the classification of NACA aerofoil.

The classification of NACA aerofoil includes,

Four-digit series family,

Five-digit series family,

6-series family.

11. Explain NACA four-digit Series.

1st digit represents Max.camber in hundredths of chord.

2nd digit represents Location Of Max.camber along chord from L.E in tenths of

chord.

Last two digits represent Max Thickness in hundredths of chord.

Ex. NACA-2412

2- Max camber at 0.02c

4- Max camber location at 0.4c from Leading edge.

12- Max thickness is 0.12c

12. Explain NACA five-digit Series.

1st digit when multiplied by 3/2 gives the design lift co-efficient in tenths.

2nd & 3rd when divided by 2 gives location of max camber along the chord from

Leading edge in

hundredths of chord.

4th & 5th digits gives max thickness in hundredth of chord.

Ex. NACA-23012

2- Design lift co-efficient is 0.3

30- Max camber location at 0.15c from Leading edge.

12- Max thickness is 0.12c

13. Airfoil

Symmetric airfoil

Cambered airfoil


14. NASA – National Aeronautics and Space Administration

NACA – National Advisory Committee for Aeronautics.

15. Types of engine:-

* Turbo jet

* Piston Engine

*Turbo prop

*Ramjet

* Scram jet etc.

16. The airplane always takes off against the wind because it gives more lift to the

aircraft and it gives more air circulation to the engines.

It lands against the wind because it is easy to control the aircraft and this also reduces the

length of the runway.

17.

Airplane Land vehicle

1. The airplane has more speed than land

vehicles

2.. Airplane have all six degrees of freedom

i.e. they can roll dive etc.

1. The land vehicles has less speed than

airplane.

2. and vehicles have only two degrees of

freedom.

18.

Cambered Airfoil Symmetric Airfoil

1. The cambered airfoil is also called the

asymmetrical airfoil and airfoil will be

about the chord line.

2. In cambered airfoil the camber line and

the chord lone will be different.

The symmetric airfoil will be symmetric

about the chord line.

2. In symmetric airfoil the camber line and

he chord line will be the same.

19. CL: Vs α Curve for symmetric and asymmetric airfoil.

20. Aspect ratio (AR):-

AR = (b2/s) = (Span)2/Area.

Influence:-


If the aspect ratio increases, the lift of the aircraft also increases.

21. Compressible Flow

Compressible Flow is a flow which has varying density.

22. Main types of aircraft:-

*Heavier than aircraft

* Lighter than aircraft

23. Stresses on an aircraft:-

* Tension

*compression

* Torsion

* Shear

* Bending.

24. Types of wing:-

* High wing

* Mid wing

* Low wing.

25. Pitch:-

It is the movement of the aircraft controlled by the elevator.

Roll:-

It is the motion of the aircraft controlled by the aileron.

Yawing:-

It is the movement of the aircraft controlled by the rudder.

26. An aircraft gets lift due to the pressure difference between the upper and lower parts

of the wings of the aircraft. The upper position of the wing experiences low pressure, and

lower portion of the wing experiences high pressure.

27. What are control tabs?

Servo, spring tab, balance tab, in the trailing edge of the wing is to give less force

and control the main control surface

To give more lift without operating the main control surface

To reduce the effort of the pilot.


28. List the primary components of an aircraft

1. Fuselage

2. Wing

3. Vertical and horizontal stabilizer

4. Aileron

5. Elevator

6. Rudder

7. Landing gear

8. Nacelle (which encloses the engine)

9. Engine

10. Flaps.

29. Classify airplanesBased on wing placement or position

Cantilever type monoplane

High wing

Mid wing

Low wing

Parasal wing

Semi cantilever wing

Based on wing plan form Elliptical wing

Rectangular wing

Triangular wing

Canard

Based on wing structure Cantilever

Semi-cantilever

Strut based

Based on thrust method Pusher


Tractor

Based on Landing gear Bi-cycle

Tri-cycle nose wheel landing gear

Tri-cycle tail wheel landing gear

Based on tail arrangement Conventional tail

T – tail

H – tail

V – tail

Triple tail

29. Classify flows based on Mach number

When M < 1 the flow is called subsonic

When M = 1 the flow is sonic

When M > 1 the flow is supersonic

When M is 0.8 < M<1.2 the flow is transonic

When M > 5, the flow is called hypersonic flow.

30. Give the functions of flaps, winglets and stats

Flaps – It is mainly used to produce mere lift during takeoff.

Winglets – It is used to avoid tip or trailing vortices

Slats- Mainly used to increase lift.

31. List the important instruments used in an aircraft

Air speed indicators

Altimeters

Magnetic direction indicators.

Rate of turn

Bank indicator


Artificial horizon indicator

Vertical speed indicator

PART – B. 1. Explain about the classification of NACA Aerofoils. Refer “Introduction to Flight” , Page No. 364 – 366.2. Explain the lift curve slope of aerofoils in detail. Refer “Introduction to Flight” , Page No. 263 – 266.3. Explain the drag curve slope of aerofoikl in detail. Refer “Introduction to Flight” , Page No. 310 –312.4. Explain about aspect ratio, wing loading, mach number. Refer “Flight without formula” , Page No.77-80, 145-166, 229-231.5. Explain about Centre Of Pressure and Aerodynamic centre. Refer “Introduction to Flight” , Page No. 31-32, 45-46. Refer “Fundamentals Of Aerodynamics” , Page No. 338 – 340.

UNIT – IVINTRODUCTION TO AIRPLANE STRUCTURES AND

MATERIALSPART - A

1. List Some of the materials commonly used in aircraft materials.Some of the materials used in aircraft structures are,

Aluminium, Steel, Titanium, High-Temperature Nickel Alloy, Composites.

2. What are types of fuselage structural elements?There are three types of fuselage structural structural elements namely,

Keelson, Stringers, Longeron.

3. What is the aluminium alloy commonly used in aircraft structures. Give its composition.


The aluminium alloy named Aluminium 2024 is commonly used in aircraft structures. It is also called as duralumin. The composition of duralumin is, Aluminium – 93.5 % Coppper – 4.4 %Manganese - 1.5%Magnesium – 0.6%

4. What is the advantage of wing titanium alloy in aircraft structures?The advantage of using titanium alloy is that it has better strength to weight ratio than aluminium and also retains its strength at higher temperatures.

5. Where Steel is used in aircraft structures.Steel is used in those areas which require very high strength such as wing attachment fittings, landing gears, engine fittings and flap tracks. Stainless steel an alloy of steel and chromium has good corrosion resistant property.

6. Explain the use of composites in aircraft structures.Composites are quite different from metals, which consist of a reinforcing material such as carbon fibers suspended inside the matrix binder such as epoxy resin. For the same load, a composite structure can yield at least 25% reduction in weight.

7. What are the types of construction in aircraft structures.The types of aircraft structures construction are,

Monocoque type Semi-monocoque type.

8. Explain about the wing structure of aircraft.The primary wing structure is the wing box. The main element of wing box is the wing spars which are large I-beams that run most of the span of the wing. The spars are basically cantilever beams extending from the fuselage carry-through structures.

9. Explain about the fuselage structure of aircraft.The fuselage structure is characterized by the bulk heads, which form the cross-sectional shape of the fuselage, and the longerons, which are heavy strips that run the length of fuselage and are attached to the outer edge of bulk heads.

10. List the components of turbo prop engine Propeller

Compressor

Combustion chamber


Turbine

Nozzle

11. The titanium is suitable as airframe materials for supersonic aircraft because, during the flight of a supersonic aircraft, very high temperature is generated and if an aluminium alloy is used as an airframe it would melt.

12. Components in which aluminium alloy is used Engine covering

Oil tank

Fuselage

Wing ribs.

13. Monocoque Semi-Monocoque

1. Longerons and stringers are not present in the fuselage.

1. Longerons and stringers are present in the fuselage.

14. Composite Materials Composite materials is made up of graphite (or) boron embedded in matrix or binding if epoxy.

15. Functions of ribs and spars:- The basic shape of the wing is contributed by ribs.

Spars are the principle structural members, they carry bending loads.

16. Uses of Titanium alloy:- The titanium alloy is used to withstand high temperature.

They are used to produce the airframes of supersonic aircrafts.

17. Factors influencing the selection of the structural material for an aircraft Strength

Corrosion resistance

Resistance to temperature, etc.

18. Composition of Aluminium 2024 alloy

The alloy group is copper.

It is the modification of original alloy 247 of aluminium alloy.


19. Role of stringers

Stringers are the span wise members on the inside surfaces of the

wing skin. They carry their own load and increase the stress that can be supported in

compression by the skin before buckling.

20. Monocoque:-

A stressed-skin type of construction in which the stiffness of the skin

provides a large measure of the skin provides a large measure of the strength of the

structure.

Semi-Monocoque:-

It is a stressed skin structure in which the skin is supported by a light

weight frame work to provide extra rigidity.

21. Bulkhead:-

It is a structural partition in a fuselage (or) wing. It usually divides the

fuselage (or) wing into bays.

Longerons:-

It is the main longitudinal strength carrying member of an aircraft fuselage

(or) engine nacelle.

22. Types of wrought (or) Aluminium alloy

Strain hardened alloys

Heat treatable alloys

23. Types of fuselage construction.

Truss type construction

Monocoque type.

PART – B

1. Explain about the elements of Aircraft structures.



2. Explain about the metals that are used in aircraft structures.


3. Explain about the composite materials being used in aircraft structures.

Refer “Introduction to Flight” Page No. 725 – 726.

UNIT – VPOWER PLANTS USED IN AIRPLANES

PART - A

1. Explain the principle of operation of rocket.

The rocket engine is basically non air breathing type engine where the fuel and

oxidizer are sprayed into the combustion chamber where they burn, creating a

high pressure, high temperature mixture of combustion products. The exit velocity

will be considerably high therby the thrust is high.

2. Explain how jet is used in thrust production.

The jet engine takes air from atmosphere, heats it by combustion of fuel inside the

duct and blasts the hot mixture of air and combustion products out at the back end

at much higher velocity. The jet engine creates a change in momentum of gas by

taking a small mass of air and giving it a large increase in velocity.

3. Explain how propeller is used for thrust production.

The propeller blade is nothing but a series of aerofoil section. When the propeller

revolves, each of these section strikes the air at a small angle of attack causing a

lift and drag. The lift will be the force acting at right angle to the direction of the

motion thus causing the propeller to move forward.

4. What do you mean by propeller efficiency?

Propeller efficiency is defined as the ratio of power available from the propeller to

the shaft brake power.


η = Pa/P

= Ta V∞/P

Ta – thrust available.

V∞ - freestream velocity.

5. What do you mean by Advance ratio?

Advance ratio is the one that defines how much the propeller advances for each

revolution of the propeller. It is denoted by J and is given by the expression,

J = V∞/nD.

V∞ - freestream velocity.

n – no.of propeller revolutions per second.

D – Propeller diameter.

6. Explain how piston engine is working.

The engine contains a piston moving back and forth inside a cylinder, with valves

that open and close approximately to let fresh fuel air mixture in and burned

exhaust gases out. The piston is connected to shaft via a connecting rod that

converts the reciprocating motion of piston to rotational motion of the shaft.

7. What do you mean by specific impulse of rocket engine?

Specific impulse is a comparative measure of the efficiency of different rocket

engines and is defined as the thrust per unit weight flow at sea level. It is denoted

by Isp.

Isp = T/w

8. Give the thrust equation for rocket engine.

The thrust equation for rocket engine is given by the equation,

T = mVe + (Pe - P∞) Ae

m - mass flow rate

Ve –Exit velocity

Pe – Exit pressure

P∞ - freestream pressure


Ae – exit area.

9. Give the thrust equation for thrust generated by turbojet engine.

The thrust equation for thrust by turbojet engine is,

T = mVe + (Pe - P∞) Ae

m - mass flow rate

Ve –Exit velocity

V∞ - freestream velocity

Pe – Exit pressure

P∞ - freestream pressure

Ae – exit area.

10. Give the thrust equation for thrust generated by propeller engine.

The equation of thrust generated by the propeller engine is given by,

T = LcosØ -DsinØ

L – lift

D – drag

Ø = β – α

Β – pitch angle

α – angle of attack

11. Limitations of piston engine:- The thrust produced by the reciprocating engine is very much less than that

compared to gas turbine engines.

It gives speed less than 500miles/hour.

12. Ramjet:-A ramjet is a kind of a jet which has no moving parts like fans, propeller

etc. It has a straight through duct where air is inducted through at a velocity V∞ , decelerated in the diffuser and blasted off at a very high velocity Ve.


13. Advantages of rocket propulsion:- Independent of atmospheric air

No limitation of altitude.

High thrust.

Disadvantages:- It has to carry its own oxygen as fuel.

Cannot be used for commercial purpose.

Costlier than jet.

14. Types of rocket engines:- On the basis of source of energy

i. Chemical

ii. Solar

iii. Nuclear

iv. Electrical rocket.

On the basis of propellant

i. Solid propellant

ii. Liquid propellant

iii. Hybrid on the basis of no. of stages

Based on range

i. Short range

ii. Long range rockets.

15. Cryogenic propellants:-Some liquid propellants have very low boiling points. The

most common cryogenic rocket propellants are, hydrogen (H2) and oxygen (O2).16. Advantages of rocket engines:-

It does not depend on atmospheric oxygen.

It produces more thrust.


It is used in space applications.

It is used to carry missiles.

17. Turbo fan engine is better than turbo jet engine because it combines both the advantages of turbo jet and turbo fan engines.18.

Jet propulsion Rocket propulsion 1. Oxygen is taken from the atmosphere.2. Has altitude limitation.

1.They carry their own oxygen 2. Does not have altitude limitation.

19. After burner:-The function of after burner is in increasing without changing the

dimensions of the compressor, turbine etc.20.

Turbo fan Turbo prop1. Small fan is installed with covered duct.2. High flight speed

1. Unducted fan is installed and also diameter of the propeller.2. Relatively low flight speed.

21. Classify chemical propellants. Solid propellants

Liquid propellants

22. Name some liquid propellants. Hydrogen Peroxide

Hydrozine

Nitroglycerine

Nitromethane

23. Name some solid propellants. Hetrogenous (or) Composite

Homogeneous (or) Double based mixure.

24. ISA:-

The ISA is defined as International Standard Atmosphere. It can be used to decide

the performance of aircraft in air. With this model of atmosphere it is possible to find the

required physical characteristics, at any altitude.

25. Pressure altitude:-


The altitude at which the given pressure occurs in ISA is called

pressure altitude. The altitude that is read on an a/p’s altimeter get to 29.9 in Kg is known

as pressure altitude.

26. Temperature altitude:-

The altitude which corresponds to the measured temperature in

ISA is called temperature altitude.

27. Density altitude:-

The altitude which corresponds to the measured density in ISA is

called density altitude.

28. Properties of atmosphere:-

There are four layers in atmosphere they are

Troposphere

Stratosphere

Mesosphere

Ionosphere

The pressure, density and temperature decreases with increase in altitude.

29. Absolute altitude:-Absolute altitude is defined as the sum of geometric altitude and

radius of the earth. It is denoted by the letter (ha). ha = hG + r30. Angle of incidence:-

The angle between the longitudinal axis and the chord line is called angle of incidence.

31. Wash in:-Increase in its angle of incidence near the tip; lift increases on the side of

the airplane having wash in.Wash out:-

A condition of rigging in which a wing has decrease in its angle of incidence near the tip.32. Stream lined body:-

A body which is streamlined in shape is called Stream lined body.

Here the drag is less.

Bluff body:-


A body which is not streamlined in shape is called bluff body. Here the

drag is more.

33. Aerodynamic center:-

The point within the airfoil section located at a point located at

one-fourth of the wing from the leading edge, is called aerodynamic center.

34. IAS

IAS is called as Indicated Air Speed. It is the difference between pitot pressure

and static pressure.

TAS

TAS is called as True Air Speed. It is the relative speed between aircraft and

atmosphere.

EAS

EAS is called Equivalent Air Speed. It is the speed at which aircraft would fly at a

standard sea level to experience the same dynamic pressure.

PART – B

1. Explain in detail about the operation of piston engine.


2. Explain in detail about the operation of propeller engine.


3. Explain in detail about the operation of jet engine.


4. Derive the thrust equation for jet propulsion engine.


5. Explain in detail about the operation of rocket engine.


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