MOCK EXAM 1 PHILS– AERODYNAMICS

What is the purpose of the trim tabs on control surfaces?

To relieve control pressure and maintain a desired flight condition

On what instance does negative pressure coefficient occurs?

When local velocity is higher than freestream velocity

One example of ______ is the path defined by a balloon floating in the air.

Pathline

What is the region behind a shockwave where the air has slowed down and the flow is subsonic again?

Expansion fan

What is a suitable flow model for a fluid?

All the 3 models can be used based on the need

Which of the following statements about stall speed is correct?

Decreasing the angle of sweep of the wing will decrease the stall speed

If all, or a significant part of a stall strip is missing on an airplane wing, a likely result will be

Asymmetrical lateral control at or near stall angles of attack

Translational thrust occurs when…

the tail rotor becomes more aerodynamically efficient during the transition from hover to forward flight.

These are designed to compensate for which regimes each wing planform are efficient.

variable sweep wings

_____ is the most challenging part of flying a helicopter.

Hovering

The majority of high-speed commercial aircrafts use ______.

swept back wings

What is the angle between the Mach wave and the flight path of an aircraft at supersonic speeds?

Mach angle

In powered flight (hovering, vertical, forward, sideward, or rearward)...

the total lift and thrust forces of a rotor are perpendicular to the rotor disk.

Find the temperature at 5 statute miles at standard atmosphere.

-31.58 F

Rate of descent can be minimized when the

Parasite drag equals one third of the induced drag

When landing behind a large aircraft, the pilot should avoid wake turbulence by staying

Above the large aircraft's final approach path and landing beyond the large aircraft's touchdown point.

The aerodynamic drag of a body, placed in certain airstream depends amongst others on ____

The airstream velocity

______ designs utilize concepts of two lifting surfaces. the canard acts as a control surface near the nose of the aircraft designed to create lift to pitch the nose up.

canard

Which control surface is used to counteract the effects of engine torque on a single-engine propeller aircraft?

Rudder

Laminar flow is more likely to occur at:

Low velocities

It refers to the demonstrated ratio of the change in height during a portion in climb in still air.

Climb gradient

During takeoff, ______ cause/s the rotor disk to cone upward.

Combination of centrifugal force and lift

In small airplanes, normal recovery from spins may become difficult if the

CG is too far rearward, and rotation is around the CG

In Prandtl-Glauert transformation, what happens to the shock waves that occur at supersonic speeds?

They vanish

Continuity equation states that if the area of a tube is increasing, the speed of the subsonic and incompressible flow inside is

Decreasing

Deflection of the leading edge flaps will:

increase critical angle of attack.

Every object persists in its state of rest or uniform motion in a straight line unless it is compelled to change that state by forces impressed on it.

Newton’s first law of motion

As for the other type of ailerons, ______ may be designed to function differentially and does not eliminate the effects of adverse yaw.

frise-type ailerons

For ______, small holes are incorporated in the surface of a wing upstream of the separation point where the air in the boundary layer is sucked into the wing.

boundary layer suction

Which type of drag dominates at high supersonic speeds?

Wave drag

On most aircraft, how are the ailerons controlled by the pilot?

By pushing and pulling on the control yoke or stick

In the context of Prandtl-Glauert transformation, when the flow speed approaches the speed of sound (Mach 1), the transformed variable becomes:

Constant

Induced drag can be reduced by

High aspect ratio wings

The minimum value of V2 must exceed "air minimum control speed" by:

0.1

Changes in the center of pressure of a wing affects the airplane’s

Aerodynamic balance and controllability

These are the other terms for First-Order Approximation, except?

Exact Theory

The greatest stress on a rotating propeller occurs

at the root

Which of the following is not a disadvantage of the blow-through tunnel?

Requiring great power

Wind tunnels for intermittent operation may be of the

both types

How does the wake turbulence vortex circulate around each wingtip?

Outward, upward, and around each tip.

If the power available is assumed to be independent of flight speed, the maximum rate of climb occurs when

The power required is minimum

Which part of the airplane provides the greatest positive contribution to the static longitudinal stability?

Horizontal stabilizer

The tendency of an aircraft to ‘weathercock’ into the wind to maintain directional equilibrium.

Directional static stability

During a spin to the left, which wing(s) is/are stalled?

Both wings are stalled

Equivalent skin friction coefficient may include ______________.

skin friction and separation drag

What is the purpose of using flaps during takeoff and landing?

To increase lift and drag

______ is the slowing down of the air after it has left the working section.

Diffusion

Which parameter does the Prandtl-Meyer expansion fan depend on?

Mach number

Which of the following flow is practically impossible in nature?

Inviscid flow

Turbulent flow is characterized by:

Chaotic and unpredictable fluid motion