Ex/PGE/9603/121/2004
MASTER OF CONTROL SYSTEM ENGG.
EXAMINATION, 2004
1st Semester
ROCKETS AND MISSILES
Time : Three hours
Full Marks : 100
Answer any five questions.
Taking at least one question from Group B.
GROUPA
1.
a)
Explain in detail the loads which the air-frame are to
withstand.
b)
How does a wake form ? What steps are to be taken
up to reduce pressure drag ?
c)
What is meant by downwash ? Explain how loss of lift
occurs due to wake and downwash.
2.
a)
8+6+6
How would a spacecraft orbiting in one orbit could
catch up a spacecraft orbiting in the higher orbit ?
b)
We wish to launch a satellite which would orbit the
earth 500 Km above the surface of the earth. Describe
the necessary steps and arrangements to put the satellite
in orbit at 500 Km attitude.
c)
Calculate the velocity of the vehicle necessary to be in
c i r c u l a r orbit at 500 Km a l t i t u d e if Gravitational
[Turn Over]
( 2 )
constant G = 6.67 10-11 Nm2Kg2, Mass of Earth =
5.975 x 1024 Kg and Mean Radius of Earth = 6371 Km.
What would be the escape v e l o c i t y
at 500 Km
altitude ?
a)
6+8+6
Why majority of launch sites are located as close to the
equator as possible ? When the velocity of rotation of
Earths surface at Launch site subtracts algebrically to
the velocity of the satellite ?
b)
Define
Specific
Impulse.
Show
that
the
Specific
Propellant consumption is the reciprocal of the specific
impulse.
c)
Define Propellant mass fraction. Show how it is related
to instantaneous mass m at any time t and all up mass
mo . Assume propulsion time as tp.
a)
6+6+8
Derive the equations of motion of a space v e h i c l e
moving in rectilinear equilibrium flight assuming all the
control forces, lateral forces and moments that tend to
turn
the
vehicle
is
zero.
The
trajectory
is
two
dimensional and is contained in a fixed plane. The
vehicle is inclined to the flight path at an angle of attack
and and are the angles of flight path and direction
of thrust F with the horizontal. Assume L and D as the
aerodynamic Lift and Drag force respectively. Show the
effect of Specific Impulse Isp.
b) Explain why multistage rockets are used ? What is the
function of strap-on boosters ?
12+8
(3)
5.
a)
Explain with the h e l p of a schematic diagram the basic
components of l i q u i d propellant rocket engine.
b)
Explain with diagram the different types of injector in
l i q u i d propellant rocket engine.
c)
List the advantages of l i q u i d propulsion system.
8+8+4
6.
a)
Explain the reasons for having different solid propellant
grain configurations. What are the different modes of
burning of solid propellant rocket motor ?
b)
How solid propellants may be classified ? Explain the
characteristics and chemical compositions of each class
of solid propellants.
c)
What are the advantages and disadvantages of solid
propellant ?
8+8+4
GROUP-B
7. a)
Distinguish between the longitudinal and lateraldirectional motions of an air-plane.
Give a short overview of the convention used for
indicating
the
positive
directions
for
resultant
aerodynamic forces and moments about axes, linear
velocities along axes and the angular velocities and
displacements about axes assuming a r i g h t
handed
co-ordinate system.
[Turn Over]
(4)
Discuss the motion of an air-plane propelled by rockets
in the x-z plane in a steady climb. Derive an expression
for the angle of climb under equilibrium condition in
terms of gross weight of the air-plane, the thrust and
the aerodynamic drag on the air-plane.
b)
12
An air-plane goes into a vertical power drive directly
over its target at a constant velocity of 900 Km/h. An
anti-aircraft gun fires a shell vertically upwards with an
initial velocity of 600 m/s when the plane is at 1805 m
elevation.
i)
Find the elevation at which the shell hits the plane and
the time required for that. Neglect air resistance.
ii)
If the shell misses the plane and the plane releases a
bomb at 1400 m elevation, how long there after would
the bomb reach the target at zero elevation and with
what velocity does the bomb strike the target ?
8.
a)
Write notes on :
i) Use of n and t co-ordinates for describing the
velocity and the acceleration vectors for curvilinear
motion of a particle.
ii) Euler equations of motion of an air-plane derived
w.r.t. a set of axes fixed in it.
iii) Relative motion analysis for plane motion.
5
3
b) The rocket is fired vertically and tracked by the radar
shown (Fig.
1), when reaches 57, other
(5)
corresponding measurements give the values r = 8.66
Km,
= 19.5 m/s2 and
Calculate
the
= 0.015 rad/s.
magnitudes
of
the
acceleration of the rocket at this position.
velocity
and
7
