Performance + Limitations Flashcards
4 dynamics of force
lift, weight, thrust, drag
what flight condition will result in the sum of opposing forces being equal
in steady-state, straight-and-level, unaccelerated flight
what is an airfoil? Example?
device which gets a useful reaction from air moving over its surface, namely LIFT. Wings, horizontal stabilizer,
what is angle of incidence
angle formed by the longitudinal axis of airplane and the chord of the wing. measured by angle which wing is attached to the fuselage
what is relative wind
direction of airflow with respect to the wing
what is the angle of attach
angle between the wing chord line and direction of the relative wind
what is Bernoulli’s principle
the pressure of a liquid or gas decreases at points where the speed increases
example of Bernoullis principle
the wing has increased velocity above its surface, decreasing pressure above the airfoil
what are several factors that affect both lift and drag
wing area, shape of the airfoil, angle of attack, velocity of the air, air density
what is torque effect
involves newtons 3rd law, as the prop is turning in one direction, the airplane wants to go the opposite direction
what reaction does torque effect have on the airplane in the air
it wants to make the airplane roll
what reaction does torque effect have on the airplane on the ground
during the takeoff roll, since the left side of the airplane is being forced down by torque reaction, more weight is on the left causing more drag and friction making left turning tendency
what are the 4 left turning tendencies
torque effect, gyroscopic precession, p-factor, and slipstream
describe the torque effect left turning tendency
rotation of prop (from the cockpit) to the right, tends to roll/bank the airplane to the left
describe gyroscopic precession left turning tendency
if the axis of the prop is tilted, the resultant force will be excepted 90 degrees ahead in the direction of the rotation
describe the slipstream left turning tendency
the slipstream strikes the vertical tail surface on the left side pushing the tail to the right and yawing it to the left
describe p-factor left turning tendency
the downward moving blade moves faster than the other side meeting the relative wind causing greater thrust on the downward part on the right side and forces the plane to war to the left
what is centrifugal force
the “equal and opposite reaction” of the airplane to change in direction and it acts “equal and opposite” to the horizontal lift component
what is load factor
the ratio of the total load supported by the airplanes wing to the actual weight of the airplane + contents
why is load factor important to pilots (2 reasons)
- the dangerous overload that is possible to impose on the aircraft structure
- an increased load factor increases stalling speed and makes it possible at seemingly safe flight speeds
what situations can result in load factors reaching maximum extent
level turns - especially those after45/50 degrees of bank
turbulence - can change angle of attack suddenly, resulting in large loads
speed - the amount of excess load that can be imposed on wind depends on how fast the airplane is flying
what are the different operational categories of aircraft?
normal, utility, aerobatic
what operational category is the C-172S
normal/utility
what does an increase in load factor have on stalling speeds
as it increases, stalling speed increases
define the term maneuvering speed
the maximum speed at which the limit load can be imposed without causing structural damage
what is the effect on maneuvering speed with an increase or decrease in weight
maneuvering speed increases with an increase in weight and decreases with a decrease in weight
define loss-of-control-inflight (LOC-I)
a significant deviation of an aircraft from its intended flight path and is most common when maneuvering
what causes an airplane to stall
an excessive angle of attack with a disruption of airflow over the wing
what is a spin
a controlled or uncontrolled maneuver which the airplane depends on a helical path.
what causes a spin
exceeding the critical angle of attack while applying excessive or insufficient rudder, one wing is more stalled than the other
when is a spin most likely to occur
engine failure during takeoff on climb out, a slip or skid from base to final, engine failure on approach to land, and a go around with full nose-up trim
how to recover from stall (PARE
Power - idle
Ailerons - neutral
Rudder - full opposite against rotation
Elevator - fully forward, breaks stall
what causes adverse yaw
when the airplane turns, the downward deflected aileron produces more lift than the opposing one. Since it produces more lift, it produces more drag, attempting to pull it the opposite direction of the turn
what is ground effect
a condition of improved performance by the airplane when operating near the ground. too much airflow going over wings so it cannot land
problems caused by ground effect
it can become difficult to lift off and land
what is empty weight
weight of just the airframe, engine, all permanently installed equipment, and unusable fuel
what is gross weight
maximum allowable weight of both airplane and its contents
what is useful load
weight of the pilot, copilot, passengers, baggage, usable fuel and drainable oil
definition of arm
horizontal distance from reference datum line to the center of gravity
definition of moment
the product of the weight of an item multiplied by its arm
define center of gravity
the point an aircraft would balance if suspended at its point
definition of datum
imaginary plane or line from which all measurements of arm are taken
equation for moment
weight x arm
equation for weight
moment/arm
equation for arm (CG)
total moment/total weight
what performance characteristics will be adversely affected with an overloaded aircraft
higher takeoff speed and longer run, reduced rate and angle of climb, lower max alt, shorter range, reduced cruising speed, reduced maneuverability, higher stall speeds, higher landing speed and longer roll
effect of a forward cg on an aircraft
higher stall speeds
slower cruise speed
more stable
greater back pressure on elevator
effects of an aft cg on an aircraft
lower stall speed
higher cruise speed
less stable
what is the weight of fuel per pound
6lbs per gallon
main elements of aircraft performance (9)
takeoff/landing distance, rate of climb, ceiling, payload, range, speed, fuel economy, maneuverability, stability
what factors affect performance of aircraft during takeoffs and landings
air density, surface wind, runway surface, upslope or downslope of runway, and weight
effect of winds taking off
headwind increases performance and tailwind decreases performance
effect of winds landing
headwind increases performance and tailwind decreases performance
effects of wind during cruise flight
headwind decreases performance and tail wind increases
how does increased weight affect takeoff and landing distances
higher liftoff speed, slower acceleration, increased drag and friction, and longer takeoff distance
what effect does an increase in density altitude have on takeoff and landing performance
increased takeoff distance, reduced rate of climb, increased true airspeed on approach and landing, and increased landing roll distance
definition of density altitude
pressure altitude corrected for nonstandard temp
how does air density affect aircraft performance
direct effect on: lift produced by wings, power output of the engine, prop efficiency, and drag forces
what factors affect air density
altitude - higher alt, less dense
temp - warmer air, less dense
humidity - more humid, less dense
study V speeds for C-172s
blah blah blah
difference between best glide speed and minimum sink
best glide - speed and config that provides greatest forward distance for a given loss of alt
minimum sink - airplane losing altitude at lowest rate
how many miles can the 172s glide per 1000ft of alt
1.5NM per 1000ft
define pressure alt
altitude indicated when altimeter is adjusted to 29.92
