ASSESSMENT AERODY 1 AERO (SUBSONIC)

Which of the folllowing airfoils and angle of attack will produce the lowest Mcrit values?

Thick airfoil at high angle of attack

Which of the following best describes the lift coefficient?

The ratio of aerodynamic and dynamic lift

An aircraft is trimmed for steady, level flight at a constant angle of attack. Without any change in thrust or control input, the pilot initiates a flap retraction. Assuming no immediate pitch correction and negligible transient effects, what is the most likely initial response of the aircraft?

Sink

A positively cambered airfoil is operating at an angle of attack where its lift coefficient becomes zero. Considering the aerodynamic characteristics about the aerodynamic center, which of the following best describes the pitching moment coefficient at this condition?

Negative

Compared with the level flight prior to the stall, the lift and drag in the stall change as follows:

Decreases, Increases

In steady, unaccelerated, straight-and-level flight, what must the vector sum of all four primary forces equal?

Exactly zero.

By aerodynamic definition, the "Lift" force vector is always oriented in which direction?

Perpendicular to the relative wind.

Based on Bernoulli’s Principle, as an incompressible fluid particle accelerates along a streamline, its static pressure will:

Decrease

An aircraft is in a steady climb at a constant velocity. As altitude increases and density drops, what adjustment is required for the Lift Coefficient?

CL must increase

Induced Drag is a direct physical consequence of which aerodynamic phenomenon on a finite-span wing?

Wing-tip vortices and downwash

The aerodynamic lift and drag forces acting on an airfoil section are fundamentally determined by which of the following

The pressure distribution over the airfoil surface

A commuter aircraft has an MTOW of 72,000 N with a wing span of 20 m and wing area of 45 sq.m. What is the span loading?

3600 N/m

Why does the stall speed recued when the flaps are being fully extended during landing?

It increases the camber and its maximum lift coefficient

Why is the "Equal Transit Time" (or "Longer Path") theory considered an incorrect explanation of aerodynamic lift?

Air molecules moving over the top surface reach the trailing edge much faster than those underneath, making equal transit time false.

Which physical pilot indication of an impending stall is caused by turbulent airflow from the stalled wing striking the tailplane?

Aerodynamic buffet

What aerodynamic phenomenon occurs due to the pressure differential between the upper and lower surfaces at the tips of a finite wing?

Wingtip vortices

Comparing two symmetrical airfoils, how does increasing the maximum thickness-to-chord ratio from 6% (NACA 0006) to 12% (NACA 0012) affect performance?

Increases CL,max by approximately 70%

Which high-lift device increases both the wing's effective camber and its physical planform area during extension?

Fowler flap

A model NACA 2412 wing with chord c=1.3 m is tested at 50 m/s under standard sea-level conditions. If the dynamic pressure q is 1531 N/m² and the lift coefficient cl is 0.63, what is the lift force generated per unit span?

1254 N/m

For a wing with a finite lift slope a=0.088 and zero-lift angle of attack L=0=-1.5°, what is the lift coefficient (CL) at an angle of attack α=4°?

0.484

Consider an airplane flying at a standard altitude of 5 km with a velocity of 270 m/s. At a point on the wing, the velocity is 330 m/s. Calculate the pressure at this point.

4.19 MPa

An aircraft like the U-2 dragon lady, has a very long narrow wings that maximized endurance. Compared to short span larger chord wings, what benefit does it get doing this design?

It has a reduces induced drag due to having a higher aspect ratio

At cruise altitude, a transport aircraft operating at relatively high true airspeed experiences reduced induced drag compared to lower-speed flight conditions. What is the primary reason for this reduction?

The lift coefficient decreases as airspeed increases for the same weight

Which specific component of parasite drag is generated by the mixing of airflow at sharp angles on the aircraft's exterior?

Interference drag

At what specific aerodynamic condition does an aircraft achieve its absolute minimum Thrust Required (TR,min) for steady level flight?

When parasite drag is exactly equal to induced drag (CD,0=CD,i)

When calculating the total drag coefficient using CD=CD,0+CL2/πeAR, what does the Oswald Efficiency Factor (e) represent in a practical sense?

It is a ratio of elliptical shape wing effectiveness to the actual shape, making the aspect ratio less effective due to the entire aircraft's non-elliptic lift distribution and parasite variations.

For a piston-propeller aircraft, how does an increase in altitude affect the Power Available (PA) compared to sea level (PA,SL)?

PA decreases in direct proportion to the decrease in air density (PA=ηPSL rho/rhoSL).

In the drag polar equation expressed as CD=CD,0+kCL2, what variables mathematically make up the induced drag constant k?

k=1/pieAR

An aircraft weighing 10,000 lbs is operating at its maximum lift-to-drag ratio, L/Dmax=12.5. What is the absolute minimum Thrust Required (TR,min) to maintain steady level flight?

800 lbs

An aircraft has a drag polar defined by CD=0.02+0.05CL2. Using the mathematical relationship L/Dmax=14kCD,0, what is the maximum lift-to-drag ratio for this aircraft?

15.81

If an aircraft is rolled into a turn, while the airspeed is being maintained and holding altitude, the pilot must ___________________

increase thrust and angle of attack

An aircraft is flying at an altitude where the air density is 0.001756 slug/ft³ with a velocity of 200 ft/s. If the lift coefficient is 1.20, determine the wing loading (W/S) assuming steady, level, unaccelerated flight.

58.03 psf

During a steady, level, coordinated turn, the load factor (n) increases. How does this aerodynamic load factor mathematically affect the aircraft's stalling speed (Vs)

The stalling speed increases proportionally to the square root of the load factor (n).

To clear an obstacle at the end of the runway, a pilot must fly at the velocity for the maximum angle of climb (max). This specific airspeed perfectly maximizes which performance parameter?

Excess Thrust

A jet suffers a total engine failure at an altitude of 36,000 ft while en route over the sea. If the aircraft has a maximum lift-to-drag ratio (L/Dmax) of 15, what is the maximum theoretical glide distance in Nautical Miles? (Assume 1 NM = 6,076 ft and standard still air)

89 NM

An aircraft departing Cebu (CEB) is instructed by ATC to enter a holding pattern. The flying pilot executes a steep, steady, level turn at a 60-degree bank angle. Using the load factor formula n=1cos , what is the structural load factor exerted on the aircraft?

2.0 Gs

An aircraft is flying at a true airspeed (V) of 250 knots (approximately 422 ft/s) and enters a coordinated turn with a 30-degree bank angle. Using the turn rate formula ω=gtan V (where g=32.2 ft/s²), what is the approximate rate of turn in degrees per second? (Note: Multiply rad/s by 180 to convert to deg/s).

2.5 deg/sec

For safety and margin above the stall, the liftoff velocity (VLO) during takeoff is generally calculated as 1.2 times the stalling speed (VLO=1.2Vs). If an aircraft has a calculated takeoff configuration stall speed of 135 knots, what is the targeted liftoff speed?

162 knots

During dispatch planning for a flight from Manila to Hanoi, the initial gross weight (Wi) is 160,000 lbs and the estimated zero-fuel arrival weight (Wf) is 130,000 lbs. The aircraft cruises at 450 knots, has a Thrust Specific Fuel Consumption (TSFC) of 0.6 lb/(lb·hr), and cruises at an L/D ratio of 16. Using the Breguet range equation R=VTSFCLDln WiWf , what is the calculated maximum range for this fuel burn? (Note: ln 160130 ≈0.2076)

2,491 NM

A commercial jet is holding due to weather. The aircraft's current weight is 150,000 lbs, and its minimum reserve weight is 120,000 lbs. The engines have a TSFC of 0.5 lb/(lb·hr) and the maximum L/D ratio for holding is 18. Using the turbojet endurance formula E=1TSFCLDln WiWf , what is the maximum holding time (endurance) available? (Note: ln 1.25 ≈0.2231)

8.03 hours

In the Standard Atmosphere, what is the constant lapse rate (temperature change) within the Troposphere?

Temperature decreases with altitude.

Which aerodynamic force is generated by the "rubbing" or tangential shear stress of air molecules against the aircraft skin?

Skin friction drag

To maximize endurance, an aircraft should be flown at the velocity for minimum Power Required (PR,min). What is the relationship between the drag coefficients at this specific point?

CDO=1/3CDI

An aircraft is climbing from Sea Level to 10,000 ft. Its Rate of Climb (RC) decreases linearly with altitude (h). At Sea Level, RC=2,500 fpm. At 10,000 ft, RC=1,500 fpm. The RC equation as a function of altitude is RCh=2500-0.1h. How many minutes does it take to reach 10,000 ft?

5.11 minutes

When selecting an airfoil for efficient aerodynamic performance, which of the following characteristics is most desirable?

Airfoil designed with a favorable (low/adverse) pressure gradient to delay flow separation and reduce drag

At the same Reynolds number and flow conditions, how does the boundary layer thickness of turbulent flow compare with that of laminar flow over a flat plate?

Turbulent boundary layer is thicker than laminar

Among the following flight conditions, which typically provides the highest lift coefficient CL at a given angle of attack?

Landing

In boundary layer physics, why is a turbulent boundary layer generally more resistant to flow separation than a laminar one?

It has higher kinetic energy near the surface

To achieve maximum endurance (the longest possible time aloft), a turbojet aircraft must be flown at an airspeed that minimizes fuel flow. Aerodynamically, this occurs at the velocity corresponding to:

Minimum Thrust Required (TR,min) and maximum L/D

How is Power Required (PR) fundamentally calculated from the Thrust Required (TR) in steady level flight?

PR=TR*V

An aircraft is cruising with a lift coefficient (CL) of 0.5. Its wing has an aspect ratio (AR) of 8 and an Oswald Efficiency Factor (e) of 0.85. What is the induced drag coefficient (CD,i)?

0.0117

During Steady Level Unaccelerated Flight (SLUF), assuming a negligible thrust angle, which equation represents the relationship tying all four forces of flight together?

T/W=CD/CL

Takeoff ground roll distance (STO) is directly proportional to the square of the aircraft's weight (STOW2) when all other variables (density, runway friction, thrust) are constant. A flight requires a 4,000 ft takeoff roll when loaded at 120,000 lbs. If late cargo additions increase the takeoff weight to 140,000 lbs, what is the new estimated takeoff roll distance using the ratio method?

5,444 ft

How do leading-edge slats primarily increase CL,max differently from trailing-edge flaps?

Slats re-energize the boundary layer to increase the stalling angle of attack up to 25° or more, whereas flaps reduce the stalling angle.

How does ice or frost accumulation on an aircraft wing affect the CL vs. Angle of Attack curve?

Significantly reduces CL,max and reduces the stalling angle of attack.

If an aircraft climbs to a higher altitude where the air is less dense, how is the Thrust Required (TR) curve affected?

The curve translates rightward; the minimum thrust required (TR,min) remains unchanged, but occurs at a higher velocity.

How does an increase in aircraft gross weight specifically alter the maximum rate of climb (RCmax) and the velocity required to achieve it (VRC,max)?

RCmax decreases, and VRC,max increases.

On a swept-wing aircraft, why is a tip stall particularly dangerous compared to a root stall?

Outboard suction loss shifts the Center of Pressure forward, creating an unstable pitch-up moment.

Given an infinite wing lift curve slope a0=0.106, an aspect ratio AR=10, and a span efficiency factor e1=0.95, what is the finite wing lift curve slope a?

0.0881

What is the point on an airfoil's leading edge where the relative airflow velocity drops to zero and static pressure reaches its maximum?

Stagnation point

At what angle of attack does a symmetrical airfoil (such as NACA 0012) produce zero lift (CL=0)?

0 deg

The Reynolds Number is a dimensionless parameter that represents the ratio of:

Inertial forces to viscous forces.

An aircraft maneuvering at an airspeed of 250 KTAS (422 ft/s) needs to execute the tightest turn possible. The airframe has a structural load factor limit of n=2.5. What is the aircraft's absolute minimum turn radius?

2,415 ft

According to the principles of finite wing aerodynamics, what physical action causes induced drag?

The more downwash you have from wingtip vortices, the more your lift vector points back, causing induced drag.

Which high-lift device increases both the wing's effective camber and its physical planform area during extension?

Fowler flap