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+ Contact Glenn          ## Activity If so instructed by your teacher, print out a worksheet page for these problems.

1. Why do different aircraft have different types of propulsion systems?

2. When would you use a ramjet on an airplane?

3. Find the Mach number for a subsonic airplane flying at 650 mph.
 M = Mach M =V/A V = Air Velocity M = ________________ A = 762 mph. (speed of sound)
4. Find the Mach number for a subsonic airplane flying at 525 mph.

M = ____________

5. Find the Mach number for a suubsonic airplane flying at 725 mph.

M = ____________

6. Find the velocity of a subsonic airplane flying at Mach number of .65.
 M = Mach M = V/A V = Air Velocity V = ________________ A = 762 mph. (speed of sound)
7.  Find the velocity of a subsonic airplane flying at Mach number of .80.

V = ____________

8. Find the velocity of a supersonic airplane flying at Mach number of 1.5.

V = ____________

9. Using the interactive Atmosphere Calculator, find the speed of sound, pressure and temperature at the following altitudes using English Units.
 ALTITUDE SOUND SPEED PRESSURE TEMPERATURE 1,000 ft. 5,000 ft. 10,000 ft. 20,000 ft. 25,000 ft. 30,000 ft.

10. Produce three graphs from the data recorded above, showing speed of sound, pressure, and temperature versus altitude.

11. What effect does altitude have on the speed of sound?

12. What effect does altitude have on pressure?

13. What effect does altitude have on temperature?

14. Flying at a constant speed of 600 feet per second, find the speed of sound and the Mach number at the following altitudes.
 ALTITUDE SOUND SPEED MACH NUMBER 1,000 ft. 10,000 ft. 20,000 ft. 30,000 ft.
15. Graph the changes in Mach Number at the different altitudes.

16. How does the change in altitude affect Mach Number when flying at a constant speed?

17. The thrust of a jet engine is also affected by changes in altitude. Calculate the thrust of a Pratt & Whitney JT8D-17 jet engine (17,000 pounds at sea level) at different altitudes using the temperature and pressure results from Question 9, and the following equation:

 F = thrust at altitude F sl = sea level static thrust at takeoff (17,000 pounds) P = static pressure at altitude P sl = sea level static pressure (14.7 psi) F = F sl x P/P sl x sqrt(T sl/T) T = absolute temp (temp + 460) at altitude T sl = sea level absolute temperature (520 R)

 ALTITUDE PRESSURE TEMPERATURE # THRUST 1000 ft. A. 10,000 ft. B. 20,000 ft. C. 30,000 ft. D.

18. Graph the change in thrust with altitude for the Pratt & Whitney JT8D-17 jet engine.

19. Give your conclusions on thrust and flying at different altitudes.

Related Pages:
Standards
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Propulsion Activity Index
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