ROCKET PROPULSION
HOME ASSIGNMENT 1 (Chapter’s 2 and 10)
1.
Calculate the static thrusts of the rocket and turbojet engine described in the
figure. The thrust T is the force necessary to prevent horizontal movement of
the engine. Both engines exhaust a mass flow of 40 kg/s. The ratio of air and
fuel mass flowing into the turbojet is 50:1, and in its exhaust plane the
velocity is 500 m/s and the pressure is the same as the ambient pressure. The
rocket propellant exhausts at a velocity of 3000 m/s through the area of 0.2
m
2
. The pressure in the exhaust plane of the rocket is 0.15 MPa and ambient
pressure is 0.101 MPa. (Problem 7, page 58)
Problem 7, page 58
2.
Find the ratio of the velocities of two vehicles, one powered by a liquid –
chemical rocket and the other by a solid – chemical one, when they are used
for acceleration of a 10,000 kg payload in a zero – gravity field. Both vehicles
have a total initial mass of 510,000 kg. The liquid – propellant rocket has 60%
greater specific impulse and 30% greater mass of empty vehicle (without
Page 1
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View Full Documentpropellant and payload), and the solid – propellant rocket has a structural
coefficient of
= 0.080. (Problem 1, page 508)
ε
3.
As shown in appendix VIII, the optimum arrangement for multistaging is
that the payload and structural ratio
λ
i
and
ε
i
be the same for all stages.
Consider the effect of a departure from this optimum arrangement for a three
– stage rocket with the same engine specific impulse (I
sp
= 400) for all three
stages. The mass distribution for the stages is a follows:
Stage
1
2
3
Total initial mass, kg
100,000
18,000
4,000
Propellant, kg
75,000
12,000
2,000
Payload, kg
1,025
For each stage determine
λ
i
and estimate the total velocity increment for the
three stages with drag and gravity effects neglected. (Problem 6 a, Page 509)
4.
Calculate the minimum total velocity increment and transit time that would
be required for a two – impulse transfer from the orbit of the earth into the
orbit of Mars about the sun. (Problem 11 a, Page 511)
INSTRUCTIONS:
All the question numbers, figures, page numbers and appendix VIII
correspond to book
Hill, P. and Peterson, R. 1992.
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 Spring '07
 SMITH
 Thermodynamics, Force, Spacecraft propulsion, Specific impulse

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