Exam 2-AT116

Which of the following is true? A) An aircraft flying at 50,000ft at 700mph may be supersonic but that same airplane flying at 700 mph at sea level may be subsonic. B) An aircraft flying at 50,000ft at 700mph may be subsonic, but that same airplane flying at 700moh at sea level may be supersonic C) Regardless of altitude, any aircraft flying at 700mph will be supersonic

A) An aircraft flying at 50,000ft at 700mph may be supersonic but that same airplane flying at 700 mph at sea level may be subsonic.

What controls the direction toward which the helicopter moves (translates)? A) Cyclic control B) Collective control C) Anti- torque pedals D) Speed control

A) Cyclic control

Where is the collective control located in the helicopter? A) On the pilot's left side B) In front of the pilot C) At the pilot's feet

A) On the pilot's left side

Which of the following is not an advantage of swept back wings? A) The drag on the aircraft is greatly decreased at all speeds B) At subsonic speeds there is improved yaw stability C) At high subsonic speeds the critical mach number is increased D) At fully supersonic speeds it keeps the wing tips out of the shock wave

A) The drag on the aircraft is greatly decreased at all speeds

which of the following is true of the normal shock wave that forms on a supercritical wing at M(crit) A) The shockwave forms near the trailing edge of the wing and is a weaker wave than on a normal wing. B) The shock wave forms near the leading edge of the wing and is a weaker wave than on a normal wing C) A normal wave never forms on a super critical wing; the air goes straight to an oblique wave.

A) The shockwave forms near the trailing edge of the wing and is a weaker wave than on a normal wing.

Why did early engineers believe you could not fly faster than the speed of sound? A) They believed the drag curve became exponential at the speed of sound B) They believed that life could not be sustained at supersonic speeds. C) They believed that the air became unstable at supersonic speeds.

A) They believed the drag curve became exponential at the speed of sound

Which of the following is NOT a reason that helicopter rotors turn at a constant speed? A) it reduces the induced drag on the rotor tips B) It keeps the blades from bending and breaking C) It keeps the blades from coning D) It provides for a more rapid response for lift and movement of the helicopter

A) it reduces the induced drag on the rotor tips

What causes change in the speed of sound? A. Air temperature B. Air density C. Air humidity

A. Air temperature

An expansion zone is characterized by what? A. An increase in speed to a higher supersonic speed, decreasing temperature, and decreasing pressure. B. A decrease in speed to a lower supersonic speed, decreasing temperature, and decreasing pressure C. A decrease in speed to a subsonic speed, increasing temperature, and increasing pressure.

A. An increase in speed to a higher supersonic speed, decreasing temperature, and decreasing pressure.

How do you make thin supersonic wings make life at low speed? A. Put leading and trailing edge flaps on the wing to increase the camber. B. Fly the wing at a higher AOA C. Build a wing with a greater camber D. Attach the wing with a greater angle of incidence

A. Put leading and trailing edge flaps on the wing to increase the camber.

Why is it that swept wings let you fly faster at subsonic speeds, and delay the entering of the transonic region? A. The air is given more time to climb from the leading edge of the wing to the top of the camber B. the air sliding sideways on the wing slows the air flowing over the top camber of the wing C. The wingtip vortex on a swept wing reduces the speed of the air flowing over the wing

A. The air is given more time to climb from the leading edge of the wing to the top of the camber

Which of the following defines the speed of sound? A. The rate at which pressure disturbances move through the air. B. The speed of the aircraft when it reaches the sound barrier C. The first point at which air becomes supersonic on an aircraft

A. The rate at which pressure disturbances move through the air.

What is the advantage of a wave rider aircraft? A. The shock waves compress the air before the air enters the engine B. the use of shock wave control to add thrust works over a wide range of speeds C. The system eliminates the problems with transonic shock wave problems

A. The shock waves compress the air before the air enters the engine

Why do we need a stabilator on aircraft that fly supersonic? A. There is not enough surface area with a standard fixed horizontal stabilizer and elevator B. The tail must be kept out of the way of the oblique waves from the wing tips C. Normal shock waves create too much turbulence on a standard stabilizer and elevator.

A. There is not enough surface area with a standard fixed horizontal stabilizer and elevator

which of the formulas below accurately represent Mach Number? A. True speed of aircraft/ speed of sound = mach number B. True speed of aircraft*speed of sound = mach numer C. Speed of sound / true speed of aircraft = mach number D. Speed of sound * true speed of aircraft = mach number

A. True speed of aircraft/ speed of sound = mach number

What is the term used for the increase or decrease in the angle of the main rotor AOI? A) Pitch increase B) Feathering C) Anti-torque control

B) Feathering

What do the main rotor blades do to make the helicopter rise? A) Spin faster B) Increase pitch (AOA) C) Tip forward D) Cone up

B) Increase pitch (AOA)

What is the reason that swept back wings allow an aircraft to fly faster without creating shock waves on top of the wings? A) The air slides sideways on the wing thus making a larger wing tip vortex, which delays the shockwave formation B) The air gets more time to climb up the front of the wing to the highest camber point C) The air is compressed more, and the increased temperature allows the air to move faster.

B) The air gets more time to climb up the front of the wing to the highest camber point

What causes "mach tuck"? A) The center of gravity moves toward the front of the aircraft, which makes the nose of the aircraft heavier B) The lift is created further back on the wings at supersonic speeds making the nose of the aircraft want to point downward C) Supersonic flows at the wing tip vortex changes the airflow in a manner that tries to point the nose down D) The oblique shock waves interfere with the expansion zones on the wing, which affects where lift happens on the wing.

B) The lift is created further back on the wings at supersonic speeds making the nose of the aircraft want to point downward

Which control in a helicopter primarily controls up and down movement? A) cyclic control B) collective control C) Anti-torque pedals D) Speed control

B) collective control

What does supersonic mean? A. The airplane is flying faster than mach 1 B. All airflows around the aircraft are traveling greater than mach 1 C. All airflows around the aircraft are traveling at exactly mach 1 D. All airflows are traveling around the aircraft at mach 5 or greater

B. All airflows around the aircraft are traveling greater than mach 1

What does the term "sonic" mean? A. Slower than the speed of sound B. At the speed of sound C. Faster than the speed of sound D. None of the above

B. At the speed of sound

Why is the speed of sound slower at 35,000ft than the speed of sound at sea level? A. The air is less dense B. The air is colder at 35,000ft C. The air is less humid at 35,000ft D. All of the above

B. The air is colder at 35,000ft

Why does the beginning of the transonic region differ from one type of aircraft to another? A. The temperature of the air changes with altitude B. The cross sectional area different aircraft affects the ability of the air to get out of the way of the airplane C. The density of the air varies with altitude D. The materials of which the aircraft are constructed affects the ability of the air to flow around the aircraft.

B. The cross sectional area different aircraft affects the ability of the air to get out of the way of the airplane

Which of the following is true of the pressures created on the top of a supercritical wing? A. The low pressure is concentrated in one area B. The low pressure is spread over a wider area from leading edge to trailing edge C. The airflow is increased over a supercritical wing, giving it better lift than a normal cambered wing.

B. The low pressure is spread over a wider area from leading edge to trailing edge

What is M(crit) A. Mach 1.0 B. The speed where the transonic region begins C. The fastest Mach number the aircraft can fly D. None of the above

B. The speed where the transonic region begins

What is the disadvantage of a variable sweep wing? A. The airflow does not stay attached at subsonic speeds B. The wing sweep system adds weight C. The wing produces excessive induced drag D. The wing is unstable at very high mach numbers

B. The wing sweep system adds weight

Which of the following is NOT a way to delay the onset of the critical mach number? A. Use thin wings B. Use symmetrical wings c. Use supercritical wings D. Use smaller diameter fuselages

B. Use symmetrical wings

What is the critical mach number? A. Speed of sound B. speed of the aircraft at the first evidence of localized sonic flows around the aircraft. C. the speed of the air over the wings at mach 1.0 D. The speed at which the aircraft sustains structural damage due to flying too fast.

B. speed of the aircraft at the first evidence of localized sonic flows around the aircraft.

The supercritical wing is characterized by what features? A) a large arching upper camber, and an upward arching lower camber B) A large, arching upper camber on the top of the wing C) A long, flat upper camber, and raised lower camber near the trailing edge.

C) A long, flat upper camber, and raised lower camber near the trailing edge.

What happens to drag as soon as you exit the transonic region? A) Drag increases exponentially B) Drag decreases exponentially C) Drag initially falls and then begins increasing linearly D) Drag falls the faster you go at supersonic speeds

C) Drag initially falls and then begins increasing linearly

What is the speed of the air behind an oblique shock wave? A) Subsonic B) Sonic C) Supersonic

C) Supersonic

What happens to the temperature of the air as the air passes through an oblique shock wave? A) Temperature decreases B) Temperature stats the same C) Temperature increases

C) Temperature increases

What is the advantage of the supercritical wing at high subsonic speeds? A) The overall life of the wing is greater at all subsonic speeds B) the drag is greatly reduced at all subsonic speeds C) The aircraft can fly faster without accelerating the air over the wing to a supersonic speed.

C) The aircraft can fly faster without accelerating the air over the wing to a supersonic speed.

Which of the following is NOT a problem of a swept back wing? (i.e. 3 of these things are problems and one is not a problem) A) The leading edge seems more pointed, thus reducing smooth flow over the leading edge at high angles of attack B) the longer time for the air to climb up the leading edge means that the air does not have to accelerate to as high of a speed, and so at subsonic speeds, Bernoulli derived lift at subsonic speeds is less. C) There is an increase in boundary layer on a swept wing D) Sweeping the wings aft allows airflow to move span wise toward the wing tip and causes a stronger wing tip vortex, and thus more induced drag

C) There is an increase in boundary layer on a swept wing

The approximate speed of sound on a standard day is what? A. 550mph B. 600mph C. 760mph D. 840mph

C. 760mph

When does the transonic range begin? A. At 0.79 M B. At 1.0 M C. At the first evidence of localized sonic flows around the aircraft D. At the point where the compressibility index reaches 1.0

C. At the first evidence of localized sonic flows around the aircraft

What is the "area rule" for supersonic aircraft? A) The frontal area of the fuselage should be less than 1/3 of the length of the fuselage. B) The cross sectional area should increase gradually, without abrupt increases. C. The fuselage is usually given a "wasp waist" D. Both B and C

C. The fuselage is usually given a "wasp waist"

Which of the following is NOT one of the problems with sonic booms? A. They are annoying if you have to listen to them all day B. Up close they can do damage to buildings on the ground C. They can damage the aircraft wing tips

C. They can damage the aircraft wing tips

How is lift generated on a wing at supersonic speeds? A) The air pressure speeds up on top of the wing and lowers the air pressure on top B) the pressure increase behind the oblique wave is more on the bottom of the wing and less on the top of the wing C) The pressure in the expansion zone on top of the wing is less than the pressure in the expansion zone on the bottom of the wing D) Both B and C

D) Both B and C

What causes a sonic boom? A. The sound of air leaking across shock waves from high to low pressure B. The changes in pressure are interpreted by your ears as a "booming" sound C. Pressure increases across shock waves as the waves pass over you. D. Both b and c

D. Both b and c

Who was the first person to fly faster than the speed of sound? A. Ernst Mach B. Orville Wright C. Glenn Curtis D. Chuck Yeager

D. Chuck Yeager

True or false: Pilots can hear the booms from the shock waves while flying in an aircraft is there are no other aircraft around?

False

True or false: The old space shuttle used the area rule to reduce drag on the aircraft

False

True or false; A normal shock wave is preferred over an oblique shock wave

False

True or false: Normal shock waves move back further on the wing as the aircraft moves faster

True

True or false: Shock waves and sonic booms are weaker when generated at high altitude, and dissipate over distance.

True

Air flow across a normal shock wave is characterized by which of the following? A) An increase in speed to a higher supersonic speed, decreasing temperature, and decreasing pressure b) A decrease in speed to a lower supersonic speed, decreasing temperature, and decreasing pressure c) A decrease in speed to a subsonic speed, increasing temperature, and increasing pressure.

c) A decrease in speed to a subsonic speed, increasing temperature, and increasing pressure.

Why is coning bad? A) The blades slow down when they begin to cone B) The cone produces excessive vibrations C) When blades cone, the Bernoulli Effect does not pull straight up

c) When blades cone, the Bernoulli Effect does not pull straight up

Which of the following is NOT a problem with normal sock waves? A. Normal shock waves can generate enough heat to damage the aircraft B. Normal shock waves can cause turbulence resulting in loss of flight controls. C. Normal shock waves can cause tremendous drag d. Normal shock waves decrease the air density and cause loss of lift.

d. Normal shock waves decrease the air density and cause loss of lift.

True or false: It is possible to break the windows out of buildings with supersonic shock waves

true

True or false: Regardless of the speed of the aircraft, most turbine engines (jet engines) can only operate on subsonic air flow.

true

True or false: Swept back wings create a greater wing tip vortex and induced drag at subsonic speeds

true

True or false: The swash plate changes the angle on the rotating rotor blades

true