Introduction to Aerospace Engineering
ASE 102
Final Examination
Deceri-iber 13,2003
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I. Please indicate whether the following statements are true or false: (15)
F 1,) The roll motion of an airplane is controlled by the rudder. (1)
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2.) The exhaust velocity of a rocket motor depends on the square root of the
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absolute temperature. ( I )
3.) The Montgolfier brothers were the first to fly a hot air balloon in 1783. ( I ) v
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4.) An air cooled radial reciprocating engine has a higher thrust-lo-weight ratio v'
than a liquid cooled reciprocating engine. (1)
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5.) The Northmp B-2 "stealth" bomber has a flying wing configuration. (1 ) /'
6.) To be stab1 in straight and level flight, the center of gravity must be above the
center of lift, (1)
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7 . Igor Sikorsky flew the first successful helicopter in 1939. (1)
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8. The Viking spacecraft found evidence of life on Mars when it landed on that
pIanet in 1976. (1) /
9. Turbojet engines have a lower thrust-to-weight ratio than reciprmating engines.
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(1)
10. Sir George Cayley was the first to reali
the thrust must be separated from the lift. ( 1)
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that to build a successful airplane,
I 1 . The Wright brothers invented the wind tunnel to measure the Lift of the wings
of Lheir first powered airplane. (1) /
12. The Pioneer 10 spacecraft was the first one to take pictures of the planet
Pluto. (1)
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13. The use of hydrogen as a rocket fuel yields t
given temperature in the combustion chamber. (1)
highest specific impulse for a
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14. A su essful glider - an unpowered aircraft - must have a low aspe,ct ratio
wing, (1)
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15. Helium is not a good lifting gas for a balloon because it is flammable. (1)
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11. A helium filled balloon canies a payload of 1000 lbs. The balloon weighs 3000 lbs.
and has a rahus of 100 feet. ( 10)
a.) At what altitude does the balloon fly? ~ s s u r n ethat the temperature on the
ground is the same as at altitude. ( 5 )
b.) What is the altitude at which the balloon flies if hydrogen is substituted for
helium as the lifting gas? ( 5 )
111. The U.S. Navy's Grumman F- 14 fighter aircraft has a "swing wing" configuration
wilh an aspect ratio of ten in extended position and two in the swept back configuration.
If the aircraft flies at a speed of 500 miles per hour with the wings extended, at what
speed must the airplane fly to maintain its altitude with the wings swept? { 15 )
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IV. A rocket takes off vertically from the surface of the Earth. The rocket's mass is 300
kgms., it carries a payload of 100 kgms. and uses 3000 kgms, of fuel. The specific
impulse of the rocket fuel is 300 seconds and the bum out time is 300 seconds. (30)
a,) What is the final velocity of the rocket at bum out? (10)
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h.) The rocket is now divided into two stages. The first stage carries two thirds of
the total fuel with a mass of 2000 kgms and the bum out time is 200 seconds. The
specific impulse is still 300 seconds. The first stage rocket has a mass of 200 kgms. The
second stage af the rocket has a mass of 100 kgms and carries 1000 kgms of fuel. It has a
burn out time of 100 seconds and the specific impulse is again 300 seconds, Calculate
the final velocity of the 100 kgm. payload in the case of the two stage rocket described.
V. It is now being seriously contemplated to build a base on the Moon. The Moon
revolves around its axis once every month and the same face of the Moon is always
poirlted toward the Earth. Such a base would require a satellite placed in orbit around the
Moon so that it is always located above the Iunar base, that means it should have an
orbital period of one month. How far above the lunar surface must the satelIite be placed
in its orbit so that it is always above the station? To obtain your answer you will have to
calculate the gravitational acceleration at the surface of the Moon, g,. To do that assume
that the mass of the Moon is 0.0 123 that of the Earth and that the radius of the Moon is
0.540 that of the Earth.
In your calculation, assume that the radius of the Earth is 4000
miles and that on the surface of the Eanh, the gravitational constant, g, is 32 ff/sec2.(40)
VI. A Lockheed C-130 cargo aircraft is on a mission to supply the Scott Amundsen
Station on the South Pole. The aircraft takes off from its base at McMurdo Sound, flies
3000 krn, to the South Pole, delivers 15,000 kgms. of cargo and then returns to McMurdo
Sound. The empty mass of the airplane is 50,000 kgm., the lift-to-drag ratio is 20 and the
constant, kleg in the Breguet equation is
equal to 1OOO km. How much fuel must the
airplane carry to complete the mission? (10)
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