Principles of Flight and Aircraft Construction

Comprehensive vocabulary flashcards covering fundamental aerodynamics, atmospheric principles, certification regulations, structural airframe designs, flight controls, and composite materials from Chapters 3 and 4 of the Pilot's Handbook of Aeronautical Knowledge.

By volume, the atmosphere is composed of approximately:

A. 21% nitrogen, 78% oxygen, 1%other gases

B. 78%nitrogen, 21% oxygen, 1% other gases

C. 50% nitrogen, 50% oxygen

D. 90% oxygen, 10% nitrogen

B — 78% nitrogen, 21% oxygen, 1% other gases

Air is a fluid, and like any fluid it is affected by viscosity and friction as it moves across a surface. TRUE or FALSE?

True

The thin layer of air that clings to a surface and slows near it due to friction is called the ______ layer.

Boundary

Standard sea-level atmospheric pressure, expressed in inches of mercury, is:

A. 14.70 in Hg

B. 1,013.2 in Hg

C. 29.92 in Hg

D. 59 in Hg

C — 29.92 in Hg

Standard sea-level atmospheric pressure is equivalent to 14.70 psi, or 1,013.2 millibars. TRUE or FALSE?

True

6. Under the standard atmosphere, sea-level temperature is defined as 59 ∘F, which equals ______ ∘C

15

Under the standard lapse rate, temperature decreases approximately how much per 1,000 feet of altitude gain (up to 36,000 feet)?

A. 0.5  ∘F

B. 1 ∘F

C. 2 ∘F

D. 3.5 ∘F

C — 3.5 ∘F

Pressure decreases by roughly 1 inch of mercury for every 1,000-foot increase in altitude, under standard conditions. TRUE or FALSE?

True

Pressure altitude is the height above the standard datum plane, found by setting the altimeter to ______ in Hg

29.92

Density altitude is defined as:

A. The indicated altitude on the altimeter

B. Pressure altitude corrected for nonstandard temperature

C. The height above ground level only

D. The altitude at which fuel burn is highest

B. Pressure altitude corrected for nonstandard temperature

High elevation, low atmospheric pressure, high temperature, and high humidity all tend to increase density altitude. TRUE or FALSE?

True

Because air expands and becomes less dense as temperature rises, ______ air days produce higher density altitudes.

Hot(Warm)

High density altitude conditions have the greatest practical effect on:

A. Radio frequency selection

B. Aircraft and engine performance

C. Magnetic compass accuracy

D. Cabin pressurization schedules

B. Aircraft and engine performance

Newton’s ______ law states that a body at rest tends to remain at rest, and a body in motion tends to remain in motion, unless acted on by an external force.

First

Newton’s first law is commonly known as the law of:

A. Inertia

B. Acceleration

C. Action and reaction

D. Conservation of energy

Inertia

Newton’s second law states that force is equal to mass times acceleration. TRUE or FALSE?

True

Newton’s second law explains that the greater the mass being accelerated, the greater the amount of ______ needed to accelerate it.

Force

Newton’s third law states that:

A. Objects in motion stay in motion

B. For every action there is an equal and opposite reaction

C. Force equals mass times acceleration

D. Pressure decreases as speed increases

B — For every action there is an equal and opposite reaction

A propeller driving air backward, and the resulting aircraft moving forward, illustrates Newton’s third law. TRUE or FALSE?

True

Bernoulli’s principle states that as the speed of a moving fluid increases, the ______ within that fluid decreases.

Pressure

A venturi tube demonstrates Bernoulli’s principle because as the passage narrows, the air inside:

A. Slows down and its pressure rises

B. Speeds up and its pressure drops

C. Speeds up and its pressure also rises

D. Stops moving entirely

B — Speeds up and its pressure drops

In a venturi tube, the wide sections on either side of the throat have slower airflow and higher pressure than the throat itself. TRUE or FALSE?

True

The same speed-pressure relationship demonstrated by a venturi tube plays out over the curved ______ surface of a wing.

Upper

Which of the following best distinguishes Newton’s and Bernoulli’s contributions to explaining lift?

A. Newton’s laws explain reaction forces; Bernoulli’s principle explains the pressure differential from airflow speed

B. They describe the exact same phenomenon with no distinction

C. Bernoulli’s principle only applies to liquids, not air

D. Newton’s laws apply only to jet engines

A — Newton’s laws explain reaction forces; Bernoulli’s principle explains the pressure differential from airflow speed

Taken together, Newton’s laws of motion and Bernoulli’s principle explain how a wing moving through the air generates ______.

Lift

The leading edge of an airfoil is its forward-most point, and the trailing edge is its rearward-most point. TRUE or FALSE?

True

The straight line drawn from an airfoil’s leading edge to its trailing edge is called the ______ line.

Chord

The mean camber line of an airfoil is:

A. The same as the chord line

B. A line drawn halfway between the upper and lower surfaces

C. The point of maximum thickness only

D. A line along the bottom surface only

An official certificate issued by the FAA once an aircraft, engine, or propeller design is confirmed to meet all applicable airworthiness standards.

The amount of curve, or camber, in an airfoil’s upper and lower surfaces helps determine how much lift it generates. TRUE or FALSE?

True

Lift can be thought of as two contributing halves: lower pressure above the wing, and ______ pressure below it.

Higher

Downwash behind a wing refers to:

A. Air deflected downward as it leaves the trailing edge

B. Air trapped beneath the fuselage

C. The boundary layer along the leading edge

D. A vortex that forms only at the wing root

A — Air deflected downward as it leaves the trailing edge

The center of pressure is the point along the chord where the airfoil’s combined aerodynamic force is considered to act. TRUE or FALSE?

True

At high angles of attack, the center of pressure moves ______ (forward/aft), toward the leading edge.

Forward

At low angles of attack, the center of pressure tends to:

A. Move forward toward the leading edge

B. Shift aft toward the trailing edge

C. Stay perfectly fixed at all times

D. Move outside the wing entirely

B — Shift aft toward the trailing edge

A deeply scooped, high-lift (concave) airfoil is well suited to short-field, low-speed operations but is too draggy for high-speed flight. TRUE or FALSE?

True

A thinner, flatter airfoil profile that minimizes drag at the cost of lower lift at a given angle of attack is described as a ______ (or high-speed) airfoil.

Streamlined

Extending leading- or trailing-edge flaps temporarily reshapes a wing into:

A. A lower-lift, lower-drag airfoil for cruise

B. A high-lift, high-drag airfoil for takeoff and landing

C. A perfectly symmetrical airfoil

D. An airfoil with no camber at all

B — A high-lift, high-drag airfoil for takeoff and landing

A symmetrical airfoil is shaped identically above and below the chord line and cannot produce lift under any circumstances. TRUE or FALSE?

False

Many aerobatic aircraft and helicopter rotor blades use symmetrical airfoils because their orientation to the airflow constantly ______.

Changes

A wingtip vortex forms because:

A. High-pressure air beneath the wing curls up and around the open tip toward the low-pressure air above

B. Cold air sinks faster than warm air

C. The engine exhaust disturbs airflow at the tip

D. Ailerons are deflected downward at cruise speed

 A — High-pressure air beneath the wing curls up and around the open tip toward the low-pressure air above

The swirling air of a wingtip vortex adds a downward component to the airflow near the tip, effectively reducing the local angle of attack and lift. TRUE or FALSE?

True

Wingtip vortex strength increases with aircraft ______, making wake turbulence a hazard for smaller aircraft following large ones at low altitude.

Weight

An upturned surface at the wingtip that acts like a dam, blocking high-pressure air from curling up and around the tip, is called a:

A. Winglet

B. Spoiler

C. Slat

D. Stabilator

A. Winglet

Winglets are now common on airliners and many general aviation aircraft as a way to reduce lift lost to the wingtip vortex. TRUE or FALSE?

True

Narrowing a wing toward its tip, known as a ______ wingtip, reduces the pressure differential available to drive the vortex without adding a separate structure.

Tapered

Both winglets and tapered wingtips are design solutions aimed at:

A. Increasing wake turbulence for training purposes

B. Reducing the lift and fuel efficiency lost to the wingtip vortex

C. Increasing the airfoil’s camber

D. Eliminating the need for ailerons

  B — Reducing the lift and fuel efficiency lost to the wingtip vortex

Wake turbulence from wingtip vortices poses a greater hazard to smaller aircraft following large, heavy aircraft at low altitude. TRUE or FALSE?

True

Air escaping around an open wingtip has nowhere else to go, since nothing stops it there the way the fuselage stops flow at the wing ______.

Root

Understanding the atmosphere and the airfoil together explains:

A. Why radio navigation works

B. Why an aircraft flies at all

C. How fuel is metered to the engine

D. Why cabins are pressurized

B. Why an aircraft flies at all

A wing generating lift has no aerodynamic trade-offs or hidden costs; wingtip vortices are purely a takeoff and landing phenomenon. TRUE or FALSE?

False