AE 1350 Homework Set #6
Due on April 16, 2008
1. Consider an aircraft patterned after Beechcraft Queen Air Executive transport.
The airplane weighs 38220 N, wing area S is 27.3 m2, aspect ratio AR is 7.5,
C L2
Oswald efficiency e is 0.9, and the drag polar is given by C D C D ,0
.
A Re
Assume the zero lift drag coefficient CD,0 is 0.03. Calculate the thrust required to
fly at a velocity of 350 km/hr at standard sea level and an altitude of 4.5 km.
2. An airplane weighing 5000 lb is flying at standard sea level with a velocity of 200
mph. At this velocity, the L/D is maximum. The wing area and aspect ratio are
200 ft2 and 9.5, respectively. The Oswald efficiency factor is 0.93. Calculate the
total drag on the airplane.
3. Consider an airplane patterned after the Fairchild Republic A-10. The wing area is
47 m2, aspect ratio is 6.5, e=0.97, gross weight is 103,047 N, and CD0 is 0.032.
The airplane is equipped with two jet engines with 40,298 N f static thrust each at
sea level. Calculate and plot the power required at sea level. Calculate the
maximum velocity at sea level.
4. Consider a Beechcraft Bonanza. AR= 6.2, S = 181 ft2, e=0.91, GW = 3000lbf,
CD0=0.027. The airplane is powered by a single piston engine of 345 HP at sea
level. The propeller has an efficiency of 0.83. Calculate the power required and
maximum velocity at sea level.
5. Assuming engine thrust available is proportional to the atmospheric (freestream)
density, find the maximum rate of climb for the aircraft in problem 3 at sea level
and at 5 km altitude.
6. For problem 4, find the maximum rate of climb at sea level and at 12000 feet
altitude. Assume the power available is linearly proportional to the freestream
density.
7. Find the absolute ceiling for the aircraft in problem 3.
8. Find absolute ceiling for the aircraft in problem 4.
9. The maximum L/D of the World War I Sopwith Camel is 7.7. The aircraft is at an
altitude of 5000 feet when the engine fails. How far can it glide in terms of
distance along the ground?
Solutions:
1.
5179 N; 3711N
2.
98.1 lbf
3.
At 100 m/sec, Power required=1129 Kilo Watts. At 220 m/sec, P=9900 KW
Power available varies as 80596 V
maximum velocity at sea level = 295 m/sec.
4.
291 ft/sec or 201 mph at sea level
5.
Rate of climb R/C at sea level=87.3 m/sec; R/C at 5 km=48.5 m/sec
6.
Rate of climb R/C at sea level=42.5 ft/sec; R/C at 12000 ft=24.6 ft/sec
7.
Use a linear curve fit for the rate of climb vs. altitude from problem 5. absolute
ceiling is 11.3 km
8.
Use results from 6. Absolute ceiling 28,500 ft
9.
Range= h (L/D)max= 7.29 miles
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