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AE AEROSPACE ENGINEERING

GATE 2011MODEL EXAM

(Read the following Instructions carefully)

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Instructions : Page 1 of 3

This question paper contains 160 pages (See the page no at the bottom right corner)

Use Up or Down (or PageUp / PageDown) Arrow for browsing.

Mark all your answer in a plain paper.

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Instructions : Page 2 of 3

This question paper contains 50 Questions.

Qn 1- 20 carry 1 mark Each

Qn 20- 40 carry 2 mark Each

Qn 41 – 50 are linked questions and carry 4 marks each

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Make a Score Sheet like one Below Qn No

Marked Ans Actual Ans Scored Mark(if Correct)

Neg. Mark(2/3 of Mark)

1

2

…

…

…

TOTAL

Calculate Final Score (Scored – Neg. Mark)

___________

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Time Counts from Here

Following 50 Questions must be Answered in 150 Minutes

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QUESTIONS

STARTS FROM HERE…!

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Qn 1- 20: Carry One Mark

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(1)In aviation, pressure altitude is

a) the altitude of the atmospheric at which the pressure is sufficient to support planform area of the aircraft.

b) an indicated altitude when an altimeter is set to an agreed baseline pressure setting of 1013.25 millibar air pressure at mean sea level (MSL) in the International Standard Atmosphere (ISA).

c) the altitude primarily used in aircraft manoeuvre operations in low high-altitude flight (below the transition altitude)

d) the altitude of the atmospheric at which the pressure difference above and below the wing alone (excluding the other components) is sufficient enough to support the aircraft.

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(2)

Variometers measure a) the rate of change of altitude by detecting the

change in total air pressure as altitude changes.b) the rate of change of altitude by detecting the

change in static air pressure as altitude changes. c) the percentage change of forward speed by detecting

the change in static air pressure as altitude changes. d) the rate of change of forward speed by detecting the

change in total air pressure as altitude changes.

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(3)In the following Fig

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Line Marked as (AAA) representsa) Altitude for max range as the density is low

and flying quality is satisfactoryb) Altitude for max endurance as the density is

low and flying quality is satisfactoryc) Altitude for pilot ejection as the aircraft lacks

necessary flying quality above this altitude.d) Altitude for pilots special attention to attain

absolute ceiling during extreme flight testing.

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(4)

In the following payload – range diagram

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Line AB, BC and CD respectively represents

a) max take weight off limit, Max payload limit, and max fuel load limit.

b) max fuel load limit, max payload limit, and max take off weight limit.

c) max payload limit, max take off weight limit and max fuel load limit

d) None of the above

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(5)

In a 5-digit airfoils nomenclature : NACA 23021, the location of the maximum camber along the chord line

a) 20% of cb) 30% of cc) 21% of cd) 15% of c

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(6)

Wind tunnel data was taken on an airfoil and the following data taken at the 1/3 chord location:

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The location of the aerodynamic center lies at , a) 0.213cb) 0.233cc) 0.250cd) 0.333c

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(7)

An aircraft has a wing area of 350 m2 and a wing span of 50 m, the wing efficiency factor is 0.85, its lift curve slope (taking a0 as 2) will be (in per radian)

a) 3.725b) 4.726c) 5.231d) 5.316

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(8)Find the Wrong staement on Load Factora) It is traditionally referred to as ‘g’, because of the relation

between load factor and apparent acceleration of gravity felt on board the aircraft.

b) Although, it is traditionally referred to as ‘g’, it does not take the unit of acceleration due to gravity (m/s2) , and it is non-dimensional.

c) An observer on board an aircraft performing a turn with a load factor of 2 (i.e. a 2 g turn) will see objects falling to the floor at twice the normal speed.

d) In a turn with a 60° angle of bank, the load factor is +2, because it is the reciprocal of cosine of the angle of bank.

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(9)

If the wing area is 80 m2, aspect ratio is 10, the taper ratio 0.3, then the root and tip chord length (in m),

a) 3.22, 2.14b) 2.33, 1.26c) 4.35,1.3d) 3.14,1.75

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(10)Find the wrong statement on tail winga) The conventional configuration with a low horizontal tail is a natural

choice since roots of both horizontal and vertical surfaces are conveniently attached directly to the fuselage.

b) In conventional configuration, the effectiveness of the vertical tail is less because interference with the fuselage and horizontal tail increase its effective aspect ratio.

c) A T-tail is often chosen to move the horizontal tail away from engine exhaust and to reduce aerodynamic interference.

d) V-tails combine functions of horizontal and vertical tails and chosen because of their increased ground clearance, reduced number of surface intersections, but require mixing of rudder and elevator controls and often exhibit reduced control authority in combined yaw and pitch maneuvers.

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(11)Due to the presents of a positive dihedral in the wing, When an aircraft rolls,

a) the lower wing presents a shorter span as seen from the direction of the approaching air, and the lower wing has reduced angle of attack and hence the effect is to destabilize the aircraft .

b) the lower wing presents a shorter span as seen from the direction of the approaching air, and the lower wing has increased angle of attack but the net effect is to roll the aircraft back towards the horizontal stable position.

c) the lower wing presents a larger span as seen from the direction of the approaching air, and the lower wing has reduced angle of attack but the net effect is to roll the aircraft back towards the horizontal stable position.

d) the lower wing presents a larger span as seen from the direction of the approaching air, and the lower wing has increased angle of attack and hence the effect is to roll the aircraft back towards the horizontal stable position.

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(12)In rocket testing, air with k=1.4 flows through a frictionless

channel. The speed of the air increases in the direction of the flow. At the nozzle entry, the static temperature is 323 deg K, the static pressure is 2.06785 bar and the mean speed is 150 m/s. At the exit (throat operating at chocking Condition), the specific impulse is,

a) 34 sb) 28 sc) 22 sd) 18 s1/27/2011

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(13)With respect to the following Newton's cannonball Fig, match

the table in the next page

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a) A4, B5,C1,D2,E3 b) A3, B1,C5,D2,E4 c) A3, B5,C1,D2,E4 d) A3, B2,C1,D5,E4

1 The cannonball is fired with sufficient velocity and the ball enters into circumnavigating orbit.

2 The firing velocity is higher than circumnavigational velocity.

3 The cannon fires its ball with a low initial velocity

4 The cannonball is fired with escape velocity.

5 The firing velocity is high but not sufficient to make successful orbot

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In the 200 km circular "parking" orbit, the orbital and escape velocity is

a) 5500, 10800 m/sb) 7784,11009m/sc) 8200, 12287 m/sd) 8324, 11147 m/s

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(15)

ABCD is a rectangular element in which AB = 0.6 cm and BC=0.3cm. The following velocities are measured 36 m/s along AB, 21 m/s along BC, 38 m/s along DC and 20 m/s along AD. the circulation round the element, taking CW as positive, in cm2/s,

a) + 45 b) – 45 c) +90 d) -90

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(16)Find the wrong statementa) Helmholtz’s first theorem states that the strength of a vortex filament

is constant along its length.b) Helmholtz’s second theorem states that a vortex filament cannot end

in a fluid; it must extend to the boundaries of the fluid or form a closed path

c) Helmholtz’s third theorem states that in the absence of rotational external forces, a fluid that is initially irrotational remains irrotational.

d) Kelvins theorem in fluid dynamics states that the circulation (defined as the line integral of the component of velocity tangential to the closed contour) in an inviscid and compressible fluid subject to only conservative forces is constant.

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(17)The slat is a) a spanwise channel cut through the wing just behind the leading edge

to make airto flow more smoothly over the upper surface while at a high angle of attack

b) a small aerofoil shaped device attached just in front of the wing leading edge to properly direct the airflow at the front of the wing to make it to flow more smoothly over the upper surface while at a high angle of attack.

c) typically consist of a small triangular fillet between the wing leading edge root and fuselage

d) "bleed air" from the jet engine's compressor or engine exhaust which is blown over the rear upper surface of the wing and flap, re-energising the boundary layer.

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(18)

LAMINAR SUBLAYER is aa) Thin layer of solid in the vicinity of the interface

where turbulent fluctuations of solid are dampedb) very thin layer of the fluid where turbulent

fluctuations are damped.c) very thin layer of the fluid near the outer boundary

layer edge where turbulent fluctuations are dampedd) very thin layer of fluid in the free stream where

turbulent fluctuations are amplified

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(19)

In a supersonic flow, a sphere encounters aa) Normal shock waveb) Oblique shock wavec) Bow shock waved) Expansion wave

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(20)

The limitation of Airy’s Stress function does not include:a) It is applicable only to plane strain or plane stress problemb) It can only be used if the body force has a special form, in

which body forces are a derivative of a scalar function of positions.

c) It is approach works best for problems where a solid is subjected to prescribed tractions on its boundary, rather than prescribed displacements.

d) It is impossible to manually find a solution in a finite number of steps by this method.

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Qns 21 – 40 Carry 2 Marks Each

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(21)

If the supersonic flow with M 1 = 2.2, encounters a NSW, the % increase in density,

a) 95b)125c) 155d)195

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(22)

If the supersonic flow with M 1 = 2, encounters a NSW and its temperature becomes 450K after passing through the NSW, the initial temperature, in K, is

a) 125b) 225c) 267d) 375

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(23)

Wave drag reduction method includes,a) Use of subcritical airfoilb) Use of a swept wingc) Use of boundrty layer blowingd) Use of diehedral wing

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Common Data for Qn 24 and 25

If Airy’s stress function is given as

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(24)Then the normal stress in x and y direction is given asa) Cx+Dy and Ax + Byb) Cx-Dy and Ax - Byc) Dx+Cy and Bx + Ayd) Cxy+Dy and Ax + Byx

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(25)

The shear stress is a) (Bx + Cy)b)-Bx + Cyc) Bx - Cyd) –(Bx + Cy)

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Common Data for Qn 26 and 27A uniform, thin-walled, cantilever beam of closed rectangular

cross-section has the dimensions shown in Fig. The shear modulus G of the top and bottom covers of the beam is 18 000N/mm2 while that of the vertical webs is 26 000N/mm2.

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The beam is subjected to a uniformly distributed torque of 20Nm/mm along its length.

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(26)

The maximum shear stress, in MPa, according to the Bred–Batho theory of torsion.

a) 23b) 83c) 92d) 98

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(27)

The angular twist in deg at the free end,

a) 0.55b) 1.10c) 1.46d) 2.18

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Common Data for Qn 28, 29, and 30

A rod is subjected to 10 kN of axial load and 5 kN of shear load.

Take : Permissible tensile stress = 100 MPa = 100 N/mm2

Poisson ratio = (1/m) ==0.3

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(28)

the dia of rod acc to Max. Principal Stress Theory a) 12.4 mmb) 12.7 mmc) 13.4 mmd) 14.6 mm

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(29)

Dia of rod Acc. to Max. Shear Stress Theorya) 12.4 mmb) 12.7 mmc) 13.4 mmd) 14.6 mm

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(30)

Dia of rod acc to Max. Principal Strain Theorya) 12.4 mmb) 12.7 mmc) 13.4 mmd) 14.6 mm

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Common Data for Qn 31, and (32)

A disc is mounted on the shaft of 1.5m and 8mm radius and shaft is made of material with G=83 Gpa.When it si rotated by 8 deg, it is found to have a time period of oscillation as 2.3 sec

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(31)

The angular velocity in rad/s isa) 1.13b) 2.73c) 3.81d) 4.11

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The moment of inertia of the disc, in kg-m2

a) 18b) 29c) 32d) 48

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Common Data for Qn 33 to 35A centrifugal flow compressor has a total pressure

ratio of 4:1. The inlet eye to the compressor impeller is 30cm in diameter. The axial velocity is 130 m/s and the mass flow 10kg of air per sec. The velocity in the delivery duct of the compressor is 115 m/s. The tip speed of the impeller is 450m/s and runs at 16000 rpm with total isentropic as 78% and pressure co-efficient of 0.72. The ambient conditions are 1.03 kgf/cm2 and 15°C. Calculate :

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(33)the static pressure (kPa) and temperature (K) at

the inlet

a) 80, 220b) 90, 210c) 90, 280d) 100, 320

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(34)Blade angle in deg at the hub and tip area) 25, 38b) 29, 42c) 32, 46d) 48, 26

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(35)The mach no at the inleta) 0.63b) 0.71c) 0.84d) 0.88

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Common Data for Qn 36 to 37

A jet aircraft is flying at an altitude of 4900 m (density=0.0.748 kg/m3), ambient pressure is 55 kPa and temperature is 255K. The velocity of the AC is 792 kmph. The pressure ratio across the compressor is 5. Take max temperature 1200K

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(36)

The temperature and pressure at the exit of the turbine are

a) 880 K and 180 kPab) 980 K and 190 kPac) 1040 K and 225kPad) 1100 K and 250kPa

880 K and 180 kPa

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(36)

Determine the velocity (relative to the AC) of the jet leaving the engine.

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(37)

The velocity (relative to the AC) of the jet leaving the engine.

a) 770 m/sb) 832 m/sc) 928 m/sd) 988 m/s

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Common Data for the Operating Rocket are as alonside for Qn 38 to 40

c

a

c

p 7000000Pa

p 102000Pa (Sea level)

T 2700K

m 3kg / s

R 285J / kg K

1.22

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The nozzle exhaust velocitya) 1825 m/sb) 1945 m/sc) 2055 m/sd) 2130 m/s

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The velocity at the throata) 725 m/sb) 850 m/sc) 920 m/sd) 990 m/s

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The exit Mach No and the expansion ratioa) 4.2, 10.4b) 3.2, 8.6c) 2.4, 6.8d) 1.8, 8.6

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Qns 41 – 50 carry 4 Marks Each

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Common Data for Qn 41, 42, and (43)

A single stage turbine has been designed for following parameters:

Inlet temperature : 1000KAxial velocity : 260 m/sMean Blade speed : 360 m/sNozzle outlet angle : 65°Stage swirl angle : 10°

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(41)

Blade inlet and outlet angles in deg are

a) 37 and 57b) 17 and 37c) 17 and 57d) 37 and 17

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(42)

The degree of reaction and temperature drop coeff

a) 0.50, 1.67b) 0.29, 1.67c) 0.35, 1.16d) 0.50, 1.16

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(43)

The flow coeff and the specific work output area) 0.35, 110 kJ/kgb) 0.41, 176 kJ/kgc) 0.53, 200 kJ/kgd) 0.72, 217 kJ/kg

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Common Data for 44, 45, 46At a certain operating condition, the mid radius velocity triangle for an axial

flow compressor are shown in Fig. (in Next Page) . The stagnation pressure and temperature at inlet are 185 kPa and 340K. Take T01 = 340 K , Po1 = 185 kPa. The mid radius pressure coeff. Is given by

211

12p

w21

)pp(C

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U=150 m/s

w2

w1

C1

C2

85

35

10

75

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The work in kJ per kg and overall pressure ratio are

a) 10, 1.11b) 16 , 1.17c) 21, 1.19d) 26, 1.22

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45

The static pressure (kPa) and temperature (K) at the outlet are

a) 110, 98 Kb) 180, 320Kc) 190, 320Kd) 190, 340K

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46

The pressure coeff isa) 0.25b) 0.50c) 0.65d) 0.75

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47If Ixx = 16 a3t/3, Iyy=53a3t/24 and

Ixy= -a3t, for the section shown, then x distance of the shear centre S with respect to the intersection of the web and lower flange of the thin-walled section as in shown in Fig.

a) – 45 a / 97b) – 35 a / 77c) + 23 a / 77d) +46 a / 97

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48If Ixx = 16 a3t/3, Iyy=53a3t/24 and

Ixy= -a3t, for the section shown, then y distance of the shear centre S with respect to the intersection of the web and lower flange of the thin-walled section as in shown in Fig.

a) – 45 a / 97b) – 35 a / 77c) + 23 a / 77d) +46 a / 97

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Data for Qn 49 and 50

• A machine of mass 25 kg is placed on an elastic foundation and a sinusoidal force of 25 N is applied. The max steady state amplitude is found to be 1.3mm, and the time period is 0.22s,

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49

The natural frequency in rad/s isa) 34 b) 42c) 56d) 67

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(50)

The equivalent stiffness, in kN/m2a) 8b) 18c) 22d) 28

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THE END

NOTEThis Question Paper is not prepared in the TRUE PATTERN OF GATE, because it

does not include Maths and Other Part.It is Meant for Practice and for Self Evaluation

In actual Online Test, Carefully follow the Instructions.

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