Performance Flashcards
What is the angle of incidence?
The angle formed by the longitudinal axis of the airplane and the chord of the wing. The AOI is fixed and cannot be changed by the pilot
What are the four dynamic forces that act on an airplae?
Lift - Upward acting force
Gravity - (Weight), the downward acting force
Thrust - The forward acting force
Drag - The backward acting force
What is Relative Wind?
The direction of airflow with respect to the wing. The flightpath and relative wind are always parallel but travel in opposite direction.
What is the Angle of Attack?
The angle between the wing chord line and the direction of the relative wind. This can be changed by the pilot.
What is “torque effect”?
“Newton’s 3rd law, every action has an equal and opposite reaction”. This means that as the internal engine parts and propeller are revolving in one direction, an equal force is trying to rotate the airplane in the opposite direction. It is greatest at low air speeds with high power settings and a high angle of attack.
What effect does torque have on an airplane?
In Flight: Torque reaction is acting around the longitudinal axis, tending to make the plane roll.
On Ground: During takeoff roll, an additional turning moment around the vertical axis is induced. As you takeoff, the left side of the airplane is being forced down and more weight is placed on the left landing gear. This results in more friction/drag on the left tire rather than the right, causing the airplane to turn more to the left.
What are the four factors that contribute to torque effect?
1) Torque Reaction of the engine and propeller - “For every
What is Centrifugal Force?
Centrifugal force is the “equal and opposite reaction” of the airplane to the change in direction, and it acts “equal and opposite” to the horizontal component of lift
What is load factor?
The ratio of the total load supported by the aircraft’s wing to the actual weight of the airplane and it’s contents.
Give 2 reasons why load factor is important to pilots?
1) a dangerous overload could cause damage on the aircraft’s structure
2) An increased load factor increases the stalling speed and makes stalls possible at seemingly safe flight speeds
What is Maneuvering Speed?
The maximum speed at which abrupt control movement can be applied or at which the airplane could be flown in turbulence without exceeding design load factor limits. The aircraft will stall before the load becomes excessive
How does Maneuvering speed change with weight?
Va increases with an increase in weight, and Va decreases with a decrease in weight. Light aircraft are more vulnerable to rapid accelerations, where as a heavier aircraft is less likely to exceed design limit load factors and may be operated at the published Va speed for gross weight.
What causes an aircraft to stall?
Excessive angle of attack. Each aircraft has one specific angle of attack where the stall occurs, regardless of airspeed, weight, load factor, or density altitude. This angle is usually between 16 and 20 degrees.
What is a spin?
Aggravated stall in either a slip or skid (yaw in a stall). If a stall does not occur, and spin cannot occur.
When are spins most likely to occur?
Most likely to occur during…
1) Engine Failure during climb out/takeoff - pilot tries to stretch glide or pilot tries to make a 180 turn to return to the runway
2) Cross-control turn from base to final - pilot overshoots final and makes an uncoordinated turn at a low airspeed
3) Engine Failure on approach to landing - pilot tries to stretch glide to the runway
4) Go-Around with full nose up trim - Pilot applies power with full flaps and nose up trim, with uncoordinated use of rudder
5) Go-Around w/ improper flap retraction - Go around with rapid flap retraction resulting in sink rate and pilot pulls back
What causes “Adverse Yaw”?
When turning to the left for example, the right aileron produces lift, which also produces more drag. This drag attempts to pull the aircraft’s nose in the direction of the raised wing
What is the “Empty Weight” of an aircraft?
The airframe, engines, and all operating equipment that have fixed locations and are permanently installed in the aircraft. Includes hydraulic fluid, unusable fuel, and un-drainable oil.
What is “Gross Weight”?
The maximum allowable weight of both the aircraft and it’s contents
What is “Useful Load”?
The weight of the pilot, copilot, passengers, baggage, usable fuel and drainable oil
What is the “Center of Gravity”?
The CG is the point about which an aircraft would balance if it were possible to suspend it at that point. CG is expressed in inches from datum
What is the “Datum”?
It is an imaginary vertical plane from which all measurements are taken. This is established by the manufacturer
What are the “Arm” and “Moment”?
The arm is the distance in inches from the datum to the cg of the item
The moment is the product of the weight of an item multiplied by its’ arm
What basic equation can you use to find the CG location?
Weight x Arm = Moment
You can re-arrange this.. ex:
Arm (CG) = Total (moment) / Total (weight)
What performance characteristics can you expect from an overloaded aircraft?
Higher takeoff Speed Longer Takeoff Run Reduced rate and angle of climb Lower maximum altitude Shorter range Reduced cruising speed Reduced maneuverability Higher stalling speed Higher Landing Speed Longer Landing Roll Excessive weight on the nosewheel
What effect does a forward CG have on an aircraft?
1) HIgher Stall Speed - Stalling angle of attack is reached at a higher airspeed due to increased wing loading
2) Slower Cruise Speed - Increased drag, greater angle of attack required to maintain altitude
3) More Stable - The CG is farther forward from the center of pressure which increases longitudinal stability
4) Greater Back Elevator Pressure - Longer T/O roll, higher app speed, difficult landing flare
What effect does an AFT CG have on an aircraft’s flight characteristics?
Lower Stall Speed - Less Wing Loading
Higher Cruise Speed - Reduced drag, small AOA req. to maintain altitude
Less Stable - Stall and spin recovery are more difficult
How does weight affect Takeoff and Landing performance?
1) Higher liftoff Speed
2) Greater mass to accelerate (slower than usual acceleration)
3) Increased retarding force (drag and ground friction)
4) Longer T/O Distance
5) For landing, the aircraft will need to approach at a faster airspeed resulting in a longer landing roll
How does an increase in density altitude effect takeoff and landing performance?
1) Increased T/O distance
2) Reduced rate of climb
3) Increased true airspeed on approach and landing, same IAS
4) Increased landing roll distance
What is density altitude?
Pressure altitude corrected for nonstandard temperature
What factors affect air density?
Altitude - the higher the altitude, the less dense the air
Temperature - the warmer the air, the less dense it is
Humidity - more humid air is less dense
What is “pressure altitude” and why is it important?
The altitude above the standard datum plane. It is the altitude indicated on the altimeter with the scale set to 29.92. Pressure altitude is used to calculate density altitude, true altitude, true airspeed, and other performance data.
