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Aerodynamics II
Definitions/Questions for Aero Chapt 7-12
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03/20/2009

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Term
Fuel flow
Definition
the rate of fuel consumption by the engine, measured in pounds per hour.
Term
Maximum endurance
Definition
The maximum amt of time that an airplane can remain airborne on a given amount of fuel.
Term
Maximum range
Definition
the maximum distance traveled over the gound for a given amount fuel.
Term
Angle of Climb (AOC)
Definition
The angle between the horizon and the flight path of a climbing aircraft.
Term
Maximum AOC (angle of climb)
Definition
The climb angle that will yield the highest altitude gain in the smallest horizontal distance. Used when taking off from a short airfield or airfield surrounded by obstacles. (altitude vs. distance)
Term
Rate of Climb (ROC)
Definition
The rate at which an acft gains altitude; the vertical component of velocity.
Term
Maximum ROC (rate of climb)
Definition
The rate that yields a maximum vertical velocity in the shortest time possible. (altitude vs time)
Term
Where does Max AOC for a turbojet occur?
Definition
L/DmaxAOA and velocity
Term
Where does Max AOC for a turboprop occur?
Definition
velocity less than L/Dmax and an AOA greater than L/DmzxAOA
Term
What is max AOC airspeed (Vx) for the T-34C?
Definition
75 KIAS
Term
Combat ceiling
Definition
the altitude where power excess allows only 500 fpm rate of climb.
Term
Cruise ceiling
Definition
the altitude at which an airplance can maintain a max roc of only 300 fpm.
Term
Service Ceiling
Definition
the altitude at which an acft can maintain a max roc of only 100 fpm.
Term
Maximim glide range
Definition
the maximum distance that can be traveled in a glide as a function of altitude, wind and lift to glide ratio.
Term
3 basic types of control systems used to move the control surfaces
Definition
Conventional, power-boosted and full power.
Term
Conventional controls
Definition
forces applied tro stick and rudder pedals transferred directly to the control surrfaces via push-pull tubes, pulleys, cables and levers. (has reversibility/gives pilot feedback)
Term
Power-boosted Controls
Definition
have mechanical linkages with hydraulic, pneumatic, or electrical boosters.(has some reversibility/gives some pilot feedback)
Term
Full power controls
Definition
"fly by wire"....the pilot has no direct connection with the control surfaces.(Not reversible/artificial means of producing pilot feedback)
Term
Artificial feel
Definition
the use of any device used to create or enhance control feedback under various flight conditions.
Term
Static stability
Definition
The initial tendency of an object to move toward or away from its original equilibrium position.
Term
Stability
Definition
The tendency of an object(airplane) to return to its state of equilibrium once disturbed from it.
Term
What are the two kinds of stability?
Definition
static and dynamic
Term
Dynamic stability
Definition
The position with respect to time, or motion of an object after a disturbance.
Term
Positive dynamic stability
Definition
The initial tendency of an object to move toward its original equilibrium position after a disturbance.
Term
Negative static stability
Definition
The initial tendency of an object to continue moving away from its equilibrium following a disturbance.
Term
Neutral static stability
Definition
The initial tendency to accept the displacement position as a new equilibrium.
Term
Positive dynamic stability
Definition
When an object oscillates less and less about the equilibrium until coming to rest. (damped oscillation)
Term
Neutral dynamic stability
Definition
When an object socillates about the equilibrium position and does not dampen out. (undamped oscillation)
Term
Negative dynamic stability
Definition
When an object does not slow down but continues to climb to a higher and higher position with each oscillation and would never return to its original equilibrium position. (divergent oscillation)
Term
Windmilling
Definition
When the engine fails and the propeller blades stay flat to the relative wind. (the wind will drive the propeller blades around, windmilling increases the drag on the plane and adversely affects gllide performance.
Term
Feathering
Definition
When the individual propeller blades are turned so they are aligned with the wind.
Term
Region of normal command
Definition
Velocities above max endurance.(airspeed stability)
Term
Region of reverse command
Definition
velocities below max endurance. (airspeed instability)
Term
What curves determine fuel flow for a turboprop and a turbojet?
Definition
turboprop - power curves, turbojet - thrust curves.
Term
Define max endurance and max range
Definition
endurance = max time airborne for given amt of fuel; range = max distance over ground for given amt of fuel.
Term
What performance profiles occur at L/Dmax?
Definition
prop max range/jet max endurance
Term
What is the effect of weight on max endurance and range?
Definition
They will decrease.
Term
What happens to max endurance and max range airspeed when weight is increased?
Definition
both airspeeds will increase.
Term
What is the effect of altitude on max endurance and max range?
Definition
The higher TAS and better fuel efficiency will yield an increase in range and endurance.
Term
What effect does a tailwind have on max range/endurance?
Definition
Increases max range and doesn't affect endurance.
Term
What effect does a tailwind have on max range/endurance airspeeds?
Definition
Max range airspeed will decrease, max endurance airspeed will not be affected.
Term
what effect does lowering the landing gear have on fuel flow at maximum endurance airspeed?
Definition
Fuel flow is greatly increased.
Term
Define maximum angle of climb
Definition
the angle that achieves the greatest altitude for the minimum distance covered over the ground.
Term
How do jets and props achieve maximum angle of climb?
Definition
Full throttle; jets at L/Dmax, props slower than L/Dmax
Term
Which statement is true concerning jet and prop climb performance?
Definition
Max roc angle of attack is smaller than max aoc.
Term
What profile should a pilot fly to clear a tall obstacle on takeoff? what airspeed is this in the T-34C?
Definition
Max Angle of Climb, 75 KIAS
Term
How do altitude and weight changes affect max ROC and max AOC?
Definition
increase in alt or weight will decrease excess thrust and pwr...resulting in a decreases in max roc/aoc
Term
What is the name for the altitude at which max pwr excess equals zero?
Definition
absolute ceiling
Term
at what aoa and velocity would you achieve max glide endurance?
Definition
at AOA greater than L/Dmax and velocity less than L/Dmax
Term
at what AOA and velocity would an airplane achieve max glide range:
Definition
at L/Dmax AOA and velocity.
Term
How do altitude, weight and headwinds affect glide performance?
Definition
Increase in alt will increase both glide range and endurance. Increase in weight decreases glide endurance but does not affect glide range. a headwind will decrease glide range and have no effect on glide endurance.
Term
from 10,000 ft AGL, how far could a T-34C glide with no winds?
Definition
20 to 22 nm
Term
what item of contifuration will cause the greatest increase in sink rate?
Definition
windmilling propeller
Term
What are the throttle requirements in relation to airspeed in the region of reverse command?
Definition
decrease in airspeed requires an increase in throttle
Term
What item of configuration will cause the greatest increaes in sink rate?
Definition
windmilling propeller
Term
In the region of reverse command, what is the effect of an increase in angle of attack with no change in throttle?
Definition
If an airplane increases angle of attack without increasing the throttle, it will develop a deficit which causes either a deceleration or a descent.
Term
State the morion that each control surface creates.
Definition
Ailerons and spoilers are used for roll control. The rudder is used to yaw. The elevators are used for pitch control only.
Term
what control deflection is required to induce a nose-up pitching moment?
Definition
a nose-up pitch is created by moving the stick aft to move the elevator upward.
Term
What are the functions of the trim tabs?
Definition
Trimming reduces the force required to hold control surfaces in a position necessary to maintain a desired flight attitude.
Term
What elevator trim tab deflection is required to maintain equilibrium for a nose-up pitch attitude?
Definition
The elevator trim tab must be moved down to hold the elevator up, causing a nose-up pitch attitude.
Term
What provides aerodynamic balance for the rudder and elevator of the T-34C?
Definition
A shielded horn
Term
What is responsible for mass balancing on the elevator of the T-34C?
Definition
A lead weight in the shielded horn.
Term
What type of controld does the T-34 use? How do cockpit control inputs move the control surfaces?
Definition
Conventional controls; stick/rudder pedals directly connected to control sfc's
Term
Longitudinal stability
Definition
stability of the longitudinal axis around the lateral axis (pitch).
Term
Lateral stability
Definition
the stability of the lateral axis around the longitudinal axis (roll)
Term
Directional stability
Definition
stability of ther longitudinal axis around the vertical axis (yaw)
Term
Neutral point
Definition
the location of the center of gravity along the longitudinal axis that would provide neutral longitudinal static stability (the aerodynamic center for the entire airplane)
Term
Directional divergence
Definition
a condition of flight in which the reaction to a small initial sideslip results in an increase in sideslip angle. caused by negative directional static stability.
Term
Spiral divergence
Definition
occurs when an airplane has strong directional stability and weak lateral stability
Term
Dutch Roll
Definition
the result of strong lateral stability and weak directional stability.
Term
phugoid oscillations
Definition
long period oscillations of altitude and airspeed while maintaining a nearly constant angle of attack.
Term
Proverse yaw
Definition
The tendency of an airplane to roll in the same direction as it is yawing. (one wing advances/one retreats which creates a diff in lift btwn 2 wings & causes airplane to roll in same direction as yaw)
Term
Adverse yaw
Definition
the tendency of an airplane to yaw away from the direction of aileron roll input. (when plane rolls upgoing wing has more lift/induced drag and retards wings forward motion causing nose to yaw in opposite direction of roll)
Term
Pilot Induced Oscillations
Definition
Oscillations of attitude and angle of attack caused by the pilot trying to stop unwanted aircraft oscillations, or by the instability of the control surfaces. These inputs may result in an increase in the magnitude of the original oscillations.
Term
How do Pilot Induced Oscillations relate to the T-34C?
Definition
the T-34C is not subject to this type of oscillation since it does not have strong longitudinal static stability.
Term
Asymmetric Thrust
Definition
occurs in any airplane with more than one engine; when one engine fails the airplane can have directional control problems.
Term
slipstream swirl
Definition
when the propeller imparts a corkscrewing motion to the air. The corkscrewing air flows around the fuselage until it reaches the vertical stavilizer where it increases the AOA on the vertical stabilizer (can happen during high pwr/low airspeed)
Term
P-factor
Definition
the yawing moment caused by one prop blade creating more thrust than the other.
Term
How does the T-34 compensate for torque?
Definition
it uses the elevator trim tabs to compensate for torque.
Term
gyroscopic precession
Definition
a consequence of the properties of spinning objects.
Term
Sideslip angle
Definition
The angle bewteen the airplane's longitudinal axis and the relative wind, as seen from above.
Term
What is a spin
Definition
an aggravated stall that results in autorotation
Term
Autorotation
Definition
a combination of roll and yaw that propagates itself and progressively gets worse due to asymmetrically stalled wings.
Term
What motion does longitudinal stability concern?
Definition
the stability of the longitudinal axis around the lateral axis (pitch)
Term
How does the fuselage affect the longitudinal stability of an airplane?
Definition
it is a negative contributor to longitudinal static stability.
Term
How does the horizontal stabilizer affect the longitudinal stability of an airplane?
Definition
it is the greatest positive contributor to longitudinal static stability
Term
How does wing sweep affect the longitudinal stability of an airplane?
Definition
swept wings are positive contributors to longitudinal static stability.
Term
How does the location of the CG affect the longitudinal atability of an airplane?
Definition
If the CG is forward of the neutral point, the overall airplane has positive longitudinal stability.
Term
What effect does increasing wing sweep angle have on the location of the wing's aerodynamic center?
Definition
Sweeping the wing aft moves the AC aft.
Term
What motion does directional stability concern?
Definition
stability of longitudinal axis around vertical axis (yaw)
Term
What motion does lateral stability concern?
Definition
stability of lateral axis around longitudinal axis (roll)
Term
Load Factor (n)
Definition
the ratio of total lift to the airplane's weight (G's)
Term
load
Definition
a stress-producing force that is imposed upon an airplane or component.
Term
strength
Definition
a measure of a material's resistance to load.
Term
static strength
Definition
a measure of a material's resistance to a single application of a steadily increasing load or force.
Term
Fatigue strength
Definition
a measure of a material's ability to withstand a cyclic application of load or force
Term
Fatigue failure
Definition
the breaking or serious permanent deformation of a material due to a cyclic application of load or force.
Term
Service life
Definition
the number of applications of load or force that a component can withstand before it has the probability of failing.
Term
limit load factor
Definition
the greatest load factor an airplane can sustain without any risk of permanent deformation.
Term
What is the limit load factor of the T-34C?
Definition
+4.5 Gs -2.3 Gs
Term
Where is minimum fuel flow for a turbojet found?
Definition
on the thrust required curve
Term
Where is mimnimum fuel flow for a turboprop found?
Definition
on the power required curve
Term
Maximum endurance and maximum range are both achieved in equilibrium, level flight. Where will you look to find the velocity that the airplane must fly?
Definition
the thrust required or power required curve
Term
Maximum endurance for the T-34C is achieved at:
Definition
420 ft-lbs of torque
Term
which is faster? max range or max endurance?
Definition
max range
Term
what does a headwind do to max range?
Definition
decreases it
Term
What does a tailwind do to max range?
Definition
increases it
Term
what do headwinds and tailwinds do to max endurance?
Definition
they have on effect on it
Term
What is mas rate of climb airspeed for a T-34C?
Definition
100 KIAS
Term
What changes affect thrust and power excess and max angle of climb and max rate of climb performance?
Definition
Weight, altitude and configuration changes (landing gear/flaps)....an increase in these thing cause a decrease in Te Pe and max roc/aoc
Term
What is the max operating ceiling of the T-34C?
Definition
25,000 ft
Term
What is the maximum glide range velocity for the T-34C?
Definition
100 KIAS
Term
What is the maximum glide endurance velocity for the T-34C?
Definition
87 KIAS
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