This Aerodynamics Fundamental Questions are your preparation for aerodynamic 2 exam.

**Question:**What effect does lowering temperature and/or pressure have on the altitude reading on an altimeter?**Answer:**The indicated height is higher than the actual height.**Question:**How do you find the Reynolds Number for an airplane wing with a 4-ft chord moving at 120 mph at standard atmospheric conditions?**Answer:**4480000**Question:**When a fluid travels through a tube containing a venturi, what happens at the point of the restriction?**Answer:**It reduces pressure.**Question:**At a dynamic pressure of 5.43 kN/m2, if a plane is cruising at an altitude of 10 km with a speed of 110 m/s, what does 65 m/s refer to when the plane cruises at sea level at the same dynamic pressure?**Answer:**Equivalent airspeed**Question:**What is the Continuity equation related to?**Answer:**Mass conservation**Question:**What is Reynolds number the ratio of?**Answer:**Inertia force to viscous force**Question:**Which flow is practically impossible in nature?**Answer:**Inviscid flow**Question:**Why does atmospheric temperature increase with altitude in the stratosphere?**Answer:**Because of the presence of the ozone layer.**Question:**What is NOT a major component of the atmosphere?**Answer:**Ozone**Question:**What do the basic governing equations of theoretical aerodynamics for inviscid flow reduce to?**Answer:**Euler’s Equation

**Question:**What can virtually 99% of all aerodynamic problems be analyzed by assuming air is?**Answer:**A continuum flow**Question:**What happens to air flowing at the speed of sound when it enters a converging duct?**Answer:**Velocity decreases, pressure and density increase.**Question:**The keystone of the standard atmosphere is a defined variation of what with altitude based on experimental evidence?**Answer:**Temperature**Question:**What is not included in the triple paper “On Aerial Navigation” by George Cayley?**Answer:**Pressure gradient**Question:**Which statement about low humidity and moisture in foods during cooking is not true?**Answer:**Low humidity causes the moisture in foods to evaporate slower during cooking.**Question:**What did Leonardo Da Vinci not invent his own version of?**Answer:**Glider**Question:**In an undisturbed air stream with a pressure of 14.7 psi, density of 0.002378 slugs per cubic foot, and velocity of 500 feet per second, what is the velocity where the pressure is 13.5 psi?**Answer:**632 fps**Question:**Air at standard pressure and temperature has a density of 0.002377 slugs per cubic foot. What is the temperature if the air is compressed adiabatically to 2 atm?**Answer:**172.3 F**Question:**Alcohol (spec. Grav = 0.80) is flowing through a horizontal pipe, which is 10 in. in diameter, with a velocity of 40 fps. At a smaller section of the pipe, there is 6 psi less pressure. Assuming that the flow is smooth, what is the diameter there?**Answer:**0.73 ft**Question:**A horizontal pipe, 1 ft in diameter, tapers gradually to 8 in. in diameter. If the flow is 500 cu ft of water per minute, what is the difference between the pressures at the two sections?**Answer:**3.08 psi**Question:**The altimeter on a low-speed Piper Aztec reads 8000 ft. A pitot tube mounted on the wing tip measures a pressure of 1650 lb/ft2. If the outside air temperature is 500 R, what is the true velocity of the airplane?**Answer:**292 fps**Question:**A supersonic nozzle is also a convergent-divergent duct, which is fed by a large reservoir at the inlet to the nozzle. In the reservoir of the nozzle, the pressure and temperature are 10 atm and 300 K, respectively. At the nozzle exit, the pressure is 1 atm. Calculate the temperature and density of the flow at the exit. Assume the flow is isentropic and, of course, compressible.**Answer:**TE = 155 K, ρE = 2.26 kg/m3**Question:**Consider the flow of air through a supersonic nozzle. The reservoir pressure and temperature are 5 atm and 500 K, respectively. If the Mach number at the nozzle exit is 3, calculate the exit pressure, temperature, and density.**Answer:**1.37 x 104 N/m2, 178.6 K, 0.267 kg/m3**Question:**The altimeter on a low-speed airplane reads 2 km. The airspeed indicator reads 50 m/s. If the outside air temperature is 280 K, what is the true velocity of the airplane?**Answer:**56 mps**Question:**A pitot tube is mounted in the test section of a low-speed subsonic wind tunnel. The flow in the test section has a velocity, static pressure, and temperature of 150 mi/h, 1 atm, and 70 F, respectively. Calculate the pressure measured by the pitot tube.**Answer:**2172 lb/ft2**Question:**Two identical aircraft are stabilized in level flight. Aircraft 1 is maintaining Mach 2 at 40,000 feet. Aircraft 2 is maintaining Mach 2 at sea level. What can be said about their respective indicated and true airspeed?**Answer:**The aircraft flying at sea level are maintaining a greater IAS and TAS than the aircraft at 40,000 feet.**Question:**What change in indicated airspeed and dynamic pressure will occur when an aircraft accelerates to a greater true airspeed at a constant altitude?**Answer:**Indicated airspeed will increase.**Question:**When will the value on the aircraft’s indicated airspeed indicator equal the aircraft’s true airspeed? When the static pressure at aircraft altitude is equal to what?**Answer:**To static pressure at sea level, on a standard day.**Question:**What must a pilot do to maintain a constant indicated airspeed (IAS) during a climb?**Answer:**Increase true airspeed (TAS) as altitude increases.**Question:**If fluid flow through a venturi is said to be incompressible, what happens to the speed of the flow at the throat?**Answer:**It maintains a constant volume flow rate.**Question:**A low–speed airspeed indicator reads 200 miles per hour while the altimeter reads 6,000 feet. What is the value of the true airspeed when the ambient temperature is found to be 30 degrees Fahrenheit?**Answer:**318 fps**Question:**A standard altimeter reads 14,000 ft. When the ambient temperature is 35 degrees Fahrenheit, what is the density altitude?**Answer:**15,656 ft.**Question:**Consider the isentropic flow over an airfoil. The freestream temperature and pressure are equal to 245 Kelvin and 114.66 psi, respectively. At the point on the airfoil, the pressure is 3.6 x10^4 Pa. Calculate the density at this point.**Answer:**1.44 kg/m^3**Question:**The force against an automobile windshield is 0.012 pounds when the car is moving at 1 mile per hour. What is the force when the car is traveling at 35 miles per hour?**Answer:**14.7 lbs**Question:**Consider a Venturi tube. At point A, the diameter is 1 foot. At point B, the radius is 3 inches. What is the flow rate of water if the pressure difference is equal to 5 inches of mercury?**Answer:**3.87 ft3/s**Question:**Assume that you are ascending in an elevator at sea level. Your eardrums are very sensitive to minute changes in pressure. In this case, you are feeling a one-percent decrease in pressure per minute. Calculate the upward speed of the elevator.**Answer:**84.34 m/s**Question:**A pitot tube on an airplane flying at sea level reads 1.07 x 105 N/m2. What is the velocity of the airplane?**Answer:**98.8 m/s**Question:**Consider a point in flow where the velocity and temperature are 1,300 ft/s and 480R. Calculate the total enthalpy at this point.**Answer:**3.321 x 10^6 ft-lb/slug**Question:**The temperature and pressure at the stagnation point of a high-speed missile are 934R and 7.8 atm. Calculate the density at this point.**Answer:**0.0103 slugs/cubic ft**Question:**The temperature in the reservoir of a supersonic wind tunnel is 519R. In the test section, the flow velocity is 1385 ft/s. Calculate the test section Mach number. Assume tunnel flow is adiabatic.**Answer:**1.49