Читать книгу Flight Theory and Aerodynamics - Joseph R. Badick - Страница 76

1 An increase in static air pressureaffects air density by decreasing the density.does not affect air density.affects air density by increasing the density.

2 A decrease in temperatureaffects air density by decreasing the density.does not affect air density.affects air density by increasing the density.

3 Pressure ratio isambient pressure divided by sea level standard pressure measured in the same units.ambient pressure in millibars divided by 29.92.ambient pressure in pounds per square inch divided by 2116.sea level standard pressure in inches of mercury divided by 29.92.

4 Density ratio, σ (sigma) isequal to pressure ratio divided by temperature ratio.measured in slugs per cubic foot.equal to the ambient density divided by sea level standard pressure.None of the above.

5 According to Table 2.1, the value for the density ratio on a standard day at sea level is:0.861 71.01.50.002 377

6 Bernoulli’s equation for subsonic flow states thatif the velocity of an airstream within a tube is increased, the static pressure of the air increases.if the area of a tube decreases, the static pressure of the air increases.if the velocity of an airstream within a tube increases, the static pressure of the air decreases, but the sum of the static pressure and the velocity remains constant.None of the above.

7 Dynamic pressure of an airstream isdirectly proportional to the square of the velocity.directly proportional to the air density.Neither (a) nor (b).Both (a) and (b).

8 In this book, we use the formula for dynamic pressure, , rather than the more conventional formula, , becauseV in our formula is measured in kts.density ratio is easier to handle (mathematically) than the actual density (slugs per cubic foot).Both (a) and (b).Neither (a) nor (b).

9 True altitude equals indicated altitude:below flight level 180.during standard conditions.when the altimeter is set to 29.92”.only when the temperature is standard regardless of pressure.

10 Which of the following determines the vertical altitude above the ground:pressure altitude.indicated altitude.true altitude.absolute altitude.

11 The corrections that must be made to indicated airspeed (IAS) to obtain calibrated airspeed (CAS) areposition error and compressibility error.instrument error and position error.instrument error and density error.position error and density error.

12 The correction that must be made to CAS to obtain equivalent airspeed (EAS) is called compressibility error, whichis always a negative value.can be ignored at high altitude.can be ignored at high airspeed.can be either a positive or a negative value.

13 The correction from EAS to true airspeed (TAS) is dependent ontemperature ratio alone.density ratio alone.pressure ratio alone.None of the above.

14 Groundspeed equals ______ when zero wind at altitude.equivalent airspeed.indicated airspeed.true airspeed.calibrated airspeed.

15 An airplane is operating from an airfield that has a barometric pressure of 27.82″ Hg and a runway temperature of 100 °F. Calculate (or find in Table 2.1) the following:Pressure ratio.Pressure altitude.Temperature ratio.Density ratio.Density altitude.

16 Fill in the values below for the stations in the drawing.At station 1At station 2At station 3A1 = 10 ft2A2 = 5 ft2V3 = 80 kts.V1 = 100 kts.V2 = ?A3 = ?P1 = 2030 psfP2 = ?P3 = ?σ = 0.968H = ?q2 = ?q3 = ?

17 Using Table 2.1, calculate the dynamic pressure, q at 5000 ft density altitude and 200 kts. TAS.

18 The airspeed indicator of an airplane reads 355 kts. There are no instrument or position errors. If the airplane is flying at a pressure altitude of 25 000 ft, find the equivalent airspeed (EAS).

19 Find the true airspeed (TAS) of the airplane in Problem 18 if the outside air temperature is −40 °C.

20 Using the TAS from the previous example, when a = 594.5 kts., calculate the Mach number for the aircraft.