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Aerodynamics WMU
WMU study stack
| Question | Answer |
|---|---|
| Airplanes were developed primarily by... | the trial and error method |
| True or False- The density of water changes with depth. | False |
| who did not experiment in flight | Bernoulli |
| T or F- The first successful flight of an aircraft was accomplished with a balloon. | True |
| Aerodynamics is the study of... | Air in Motion |
| A balloon that is filled with air that is lighter than the surrounding air rises to a point where the internal air density is equal to the external air density is based on what principle? | Buoyancy |
| T or F? The density of air changes depending on altitude because air is compressible. | True |
| What part of the atmosphere does all weather occur and also most flight operations? | Troposphere |
| Air density at sea level is ________ dense than air at 10,000 feet altitude. | more |
| Balloons that are navigable are called: | Airships |
| Sir George Cayley, Otto Lilenthal, and Octave Chanute all had what in common? | They all experimented with gliders in the 1800s. |
| Lighter than air aircraft are reliant on what for lateral (as opposed to vertical) movement. | a) Movement of an air mass a) Velocity and direction of the wind |
| T or F? Man's first attempt at heavier than air flight was to create birdlike vehicles with wings that flapped. | True |
| Birds are successful fliers because they can achieve lift and thrust with their feathered wings. Airplanes require; | An engine to develop forward thrust and Controls to maneuver in pitch, roll, and yaw, and Stability in their design and Knowledgeable pilots |
| Gliders and airplanes are | a) Heavier than air machines |
| Who was/were the first to achieve sustained, controlled and powered flight? | The Wright Brothers |
| A chunk of fluid that is suspended in a container of fluid will ________ due to the weight and pressure above the chunk balancing out the higher pressure below the chunk. | a) remain still |
| A small contained bubble of fluid that is lighter than the surrounding fluid ________ due to the higher pressure on the bottom of the bubble. | Rises to the surface |
| A piece of lead placed in a container of water will ________ due to the weight of the lead being _______ than the fluid that is displaced. | a) Sink to the bottom, heavier |
| How are balloons made to be lighter than air? | a) Filled with lighter than air gas (helium) a) Filled with heated air which is less dense than cooler air |
| Pressure = …………… | a) Force/ Area |
| The symbol for air density is? | a) ρ |
| The approximate temperature at the Tropopause is; | a) -56˚C |
| Air pressure at sea level is ________ than air at 30,000 feet altitude. | More |
| The temperature of air decreases on average by how much per 1000ft? | 2C |
| The chordline of an aerofoil is: | a) A straight line joining the centre of curvature of the leading and trailing edges. |
| The Mean Camber Line of an aerofoil section is: | a)A line from the leading edge to the trailing edge equidistant from the upper and lower surfaces. |
| A cambered aerofoil set at 0˚ angle of attack in an air stream will produce: | Lift and Drag |
| The angle between the chord line of the aerofoil and the relative airflow is called: | a) The Angle of Attack. |
| Dynamic pressure is equal to: | ½ ρv² |
| The thickness : chord ratio of an aerofoil is: | The ratio of the maximum thickness of an aerofoil section to its chord. |
| The centre of pressure of an aerofoil is: | a) The point on the chordline where the resultant lift force acts. |
| If the angle of attack is increased slightly from 0˚, the center of pressure will: | a) Move forward slightly. |
| A symmetrical aerofoil section of a wing which is set at 0˚ angle of incidence will produce in level flight: | Zero Lift |
| The air on the top of a cambered wing producing lift: | a) Velocity increases, Static Pressure decreases. |
| "Aspect Ratio" is: | a) The ratio of the wingspan to the mean chord. |
| The density of a gas may be expressed as: | Mass/Volume |
| The diagram shows the Static pressure and velocity of the airflow around a wing section producing lift. Which of the below is correct? | a) P1 is less than P2, V1 is greater than V2. |
| The diagram shows the lift curves for two aerofoil sections. Which of the below is an accurate description of the diagram? | a) Airfoil A is symmetrical, but airfoil B is cambered. |
| The critical angle of attack at which a given aircraft stalls (CL(MAX)) is dependent on the: | a) Design of the wing, (camber etc). |
| Which of the below actions will result in a stall every time? | a) Exceeding the critical angle of attack. |
| An aircraft stalls when: | a) The airflow over the top surface of the wing separates which results in a large increase in drag and a large loss of lift. |
| If an aircraft’s wings are slightly angled upwards from horizontal as you look at it from the front forming a shallow V, this is called: | a) Dihedral |
| A high aspect ratio wing will be: | a) Of long span and short chord. |
| The curve on the right represents: | a) Aerofoil Lift. |
| The wing span is the distance: | a) From wing tip to wing tip. |
| A wing is tapered if: | a) The tip chord is less than the root chord. |
| The stalling angle of an aerofoil of a training aircraft is approximately: | a) 16. |
| An aircraft's wing has a mean chord of 6m and a span of 30m. The aspect ratio is: | 5 |
| How do you calculate Aspect Ratio: | a) Span²/ Area |
| The aerofoil section shown in the diagram: | a) Will give a down force because the angle of attack is negative. |
| To maintain level flight at a steady airspeed: | a) Thrust must be exactly equal to drag. |
| The stall warning vane on an aircraft wing is located: | Just below the leading edge. |
| At positive angles of attack, a wing produces most lift at: | a) Just before the stall. |
| An airplane is in steady-state level flight, therefore: | a) Thrust equals drag, Lift equals weight. |
| The term "Angle of Attack" is defined as: | a) The angle between the wing chord line and the relative wind. |
| Weight acts: | a) Always in line with gravity. |
| When a fowler flap moves back: | a) Wing area increases, camber increases. |
| When does lift act on a wing? | Center of Pressure |
| What does the "S" represent in the lift equation? | Wing Area |
| Bernoulli's Theorem states: | a) When dynamic pressure increases, static pressure decreases. |
| For a typical light training aircraft, the optimum angle of attack producing most lift for least drag is approximately: | a) +4°. |
| Wash out of a wing is: | a) A decrease in angle of incidence from root to tip. |
| An antenna of 0.05 sq. ft. of a cross-sectional area (S) produces 1 pound of drag in an airflow with a dynamic pressure (½ρv²) of 25 lbs/sq. ft. What is its drag coefficient? Drag = ½ρv² S Cd | a) .80 |
| If the landing gear is lowered: | a) Total drag increases. |
| The minimum Total Drag of an aircraft in flight occurs: | a) At the speed where parasite drag and lift induced drag are equal. |
| Lift induced drag (lift dependent drag) of an aircraft would be increased with: | a) Increased weight. |
| The boundary layer of a body in a moving airstream is: | a) A thin layer of air over the surface in which the air is retarded by the effects of friction. |
| Skin Friction drag resulting from a laminar boundary layer will be: | a) Less than from a turbulent boundary layer. |
| A landing gear leg has a drag of 30 lbs at a speed of 100 kts. Its drag at 200 kts would be: | a) 120 lbs. |
| If speed is increased from 150 kts to 300 kts, the Pressure or wake drag due to shape will be: | a) Quadruple. |
| The drag of an aircraft will: | a) Increase with an increase in air pressure. |
| Floating on landing due to ground effect will be most likely during an approach when at: | a) Less than the length of the wingspan above the surface. |
| The cause of the hazardous wake turbulence of large aircraft is the: | a) Vortices generated at the wing tips. |
| Frost on an aircraft wing will result in: | a) A decrease in lift and an increase in drag. |
| What phenomena causes Lift induced Drag? | a) Wing tip vortices. |
| What effect on lift induced drag does entering ground effect have? | a) It decreases. |
| When the undercarriage is lowered in flight: | a) Form drag will increase and the aircraft will pitch nose down. |
| The point where the boundary layer changes from laminar flow to turbulent flow is called the; | a) Transition point |
| Laminar flow has: | a) Less friction than turbulent |
| A high aspect ratio wing (High span to chord ratio, like a glider): | a) Decreases lift induced drag. |
| In straight and level flight, how does Parasite drag vary with airspeed? | a) V2 (directly with the square of the velocity) |
| Wingtip vortices: | a) Right wing rotates anti-clockwise, left wing clockwise |
| At low speed the drag on an aircraft is mainly | a) Lift Induced Drag |
| The pressure gradient on the rear side of a shape where the air is flowing from Low static pressure to High static pressure is called; | a) Adverse pressure gradient |
| The point where the air stops sticking to the shape of an object is called; | a) Separation point |
| With regard to "P.L.A.N.n.", the acronym used to determine the capacity of a reciprocating engine to produce power, the "A" refers to what? | a) Cross sectional piston area |
| The final factor (n) in determining the capability of a reciprocating engine to produce power in the anacronym P.L.A.N.n. is: | a) The number of cylinders of the engine |
| The optimum angle of attack for a propellor blade to the airflow passing through it is approximately; | 4˚ |
| With regard to P.L.A.N.n., the pilot can control which of the factors in the cockpit? | a) Mean cylinder pressure (P) by use of the throttle to control the amount of fuel and air being taken into the cylinders Engine Speed (N) |
| A propellor blade ‘slips’ through the air unlike a woodscrew or corkscrew and so cannot be 100% efficient; | a) True |
| The pitch of a propeller blade that produces the most efficiency (most thrust for least drag) for a given speed is called; | a) Optimum angle of attack |
| The resultant relative wind acting on a propellor, is the result of which two velocities? | a) Propellor’s rotational speed and aircraft’s forward speed |
| Which is faster; | a) Propellor Tip speed |
| In order to maintain a relatively constant angle of attack along the span of a propeller blade, blades are manufactured with what? | a) Blade Twist |
| Attempting to increase the top speed of an aircraft by fitting a bigger engine is difficult because; | a) Parasite Drag increases as airspeed increases and a bigger engine creates more weight induced drag |
| Which equation(s) below is/are an expression of Newton's second law? | a) Force = Mass x Acceleration |
| In a variable propeller system, as airspeed increases, the propellor must ________ to maintain the most efficient angle of attack. | a) Increase pitch |
| In the event of an engine failure (particularly important in a twin engined airplane) the propellor should automatically be turned to a minimum drag position, this is called: | a) Feathered |
| Between which two strokes of a four stroke cycle does the spark occur? | a) Compression and Power |
| What was the reason that the earlier engines had radially mounted cylinders? | a) Greater number of cylinders could be mounted and better cooling |
| Compared to jets, propellers move a ________ amount of air with a ________ acceleration. | a) Large/Small |
| Which is considered the more "efficient" producer of "thrust"? | a) Propeller driven by a reciprocating engine |
| T or F? A turbojet engine differs from a turbofan engine in that all of the air flows through the compressor section or the core of the engine, whereas some of the airflow with a turbofan engine flows around the outside of the core. | True |
| The term for the air which doesn’t pass through the core of a jet engine and get burnt with the fuel is called: | a) Bypass Air |
| The correct sequence of the four stages of a reciprocating engine are | a) Intake, compression, power, exhaust |
| T or F? A propellor blade is twisted to ensure a constant angle of attack to the relative airflow along the blade which is moving faster through the air from the hub to the blade tip. | True |
| What is the name of the part of the engine that rotates the propeller? | Crankshaft |
| 1 horsepower equals; | a) 550 foot pounds per second |
| Power= | Force x Velocity |
| T or F? A propellor accelarates a large mass of air with a relative small acceleration compared with a jet which accelerates a small mass of air with a very large acceleration; | True |
| The main factor that limits the diameter of a propellor blade is; | a) The Speed of the blade tip relative to the speed of sound |
| During the ground roll whilst accelerating along the runway before taking off, the four forces ________ in balance. | are not |
| The difference (in HP) between power avaliable and power required is called what? The difference (in HP) between power avaliable and power required is called what? | a) Excess power |
| T or F? When determining takeoff distance required, whether runway is paved or grass will affect your takeoff distance. | True |
| The reasons for having more than a twin engine rather than one engine include which of the following? | a) To provide more power than can be provided by one engine. a) Improves safety by providing redundancy in case one engine fails. Both |
| The loss of one engine in a twin engine aircraft results in: | a) Significant loss of climb capability a) Yaw in the direction of the failed engine a) Increased drag due to use of rudder to overcome yaw All of the above |
| Calculate the Rate of Climb if power available is 180 Hp and power required is 130 Hp and the weight of the aircraft is 3000 pounds. | a) 550 fpm |
| What is the rate of sink if the power available is 120 Hp and power required is 140 Hp and the weight of the aircraft is 3000 pounds. | a) 220 fpm |
| The best glide ratio is: | a) found on power required curve at the point of minimum drag. |
| WIth respect to change in velocity, what is required in order to generate enough lift to takeoff. | a) Acceleration |
| During takeoff ground roll, drag ________ thrust. | is less than |
| During takeoff ground roll, lift ________ weight | is less than |
| The drag curve, when applied to piston engine driven propellor aircraft, is recalculated and called the; | Power required curve |
| T or F? Flying at a higher velocity than where the Power Required Curve and Power Avaliable Curve cross would produce a descent. | True |
| Best angle of climb speed is: | a) The most altitude that can be obtained over a given amount of distance. a) Vx Both |
| The power avaliable curve is not straight because: | a) The propeller effciency changes depending on airspeed |
| Service ceiling is: | a) The maximum altitude in which the aircraft can achieve a climb rate of 100 fpm. |
| Identify the factors that affect takeoff distance: | a) Airport elevation a) Air density a) Slope of runway a) Direction and velocity of wind All of the above |
| Best range airspeed with a tailwind will be ________ than best range airspeed with a headwind. | a) Lower |
| T or F? Operating at maximum L/D (Lift/Drag ratio) gives speed for best glide distance and best range. | True |
| Maximum range can be affected by | a) RPM settings a) altitudes a) wind a) weight All of the above |
| Maximum range airspeed will produce what effects? | a) Maximum distance for a given amount of fuel. |
| At airspeeds slower than V(min power), more power is required to maintain altitude. What is this called? | a) Back side of the power curve. a) Region of reversed command a) "Slow flight" is an example of this situation All of the above |
| Operating at V (min power) (Minimum Power Speed) results in ... | a) Maximum endurance a) Minimum sink rate a) Most time aloft All of the above |
| T or F? Vx is less than Vy; | True |
| As altitude increases Power available; | Decreases |
| As aircraft weight increases Power required; | Increases |
| As Drag increases (from flaps and undercarriage lowered) Power required; | Increases |
Created by:
linda2013