Ch 6 - Aerodynamics Flashcards
What is the angle of incidence?
Angle between the longitudinal axis and the chord line. Remains constant. Angle is less at the wingtip than the root (near the body), resulting in smoother airflow above it and better effectiveness of the ailerons.
An airplane will stall at the root first, and at the wingtip last. Meaning ailerons are effective for longer.
What is a washout?
= The root has a higher angle of incidence than the tip (it twists downward towards the tip)
- Wings will stall at the root first, and create turbulent air which buffets the elevator. Pilot will feel this, while the tips of the wings are not stalled and remain effective. Prevents rapid rolling motion when stalled.
What is relative wind?
Wind relative to the wind. Always parallel and opposite to the direction of flight - plane is forward and downward, wind is backward and upward.
Factors that affect lift and drag?
Wing area - increase the wing surface area by deflecting the flaps, increases wing area. Increases both lift and drag but drag at a higher ratio.
Shape of the airfoil - adding flaps or aileron. Frost increases drag, decreases lift. Increasing the upper curvature of the airfoil increases lift (to a certain extent)
AOA - increase L and D to a certain point
Velocity of the air - more air over wings increases L and D
Air Density - direct relationship with L and D. AD is changed by temp, humidity, pressure
What is Torque effect?
Every action there is an equal and opposite reaction.
Greatest - low airspeed with high power (TO), and high. AOA
In air - roll to the left. Modern engines designed with engine offset to compensate, left wing can have more lift.
On ground - more weight on the left side, creating more drag. Turn to the left, need right rudder.
4 factors that contribute to torque effect
- Engine and prop - right rotation of prop turns airplane to left.
- Slipstream - corkscrews around the airplane, pushes tail to the right causing yawing to the left
- P-Factor - downward wing (right) takes bigger bite. Moves that part of the plane forward more than the left.
- Gyroscopic effect of prop
What is load factor? Risks?
LF=Lift/Weight
Combination of centrifugal force and weight when an airplane is turning.
Structural damage
Increases stalling speed at seemingly safe speeds
Affected by:
- Turns (2gs on 60 degrees)
- Turbulence -
- Speed - below maneuvering speed, plane will stall before load factor is excessive. Above, risk of structural damage with changes to flight controls/turbulence
What is centrifugal force?
Equal and opposite to horizontal lift. Wants to pull the aircraft out from the turn. When combined with weight, the two forces are greater than weight alone (ie. load factor).
Maneuvering Speed
Steady flight, one control can be fully deflected without structural damage.
Increases with weight, decreases with less weight. A lighter weight is more vulnerable to gusts and turbulence.
Situations where LOC-I can occur
LOC-I is a significant deviation from intended flight path. Often results when plane is upset.
Causes:
1. Maneuvering
2. Uncoordinated flight
3. Pilot complacency
4. Equipment malfunctions
5. Attempting to fly in IMC when pilot is not trained
AOA and Stall
Will stall at the same AOA regardless of speed, load factor, weight etc.
Situations Conducive to Spin
- Engine failure on takeoff - try to extend glide distance by pitching up or uncoordinated turn back to runway
- Engine failure on approach to land - pitch up extend glide speed
- Uncoordinated approach to land, slow speed
- Go around with full flap retraction, or with full nose up trim
What is payload?
Useful weight - fuel weight. Ie. passengers, cargo and baggage.
Main elements of aircraft performance
Speed
Maneuverability
Range
Payload
Climb rate
Takeoff and Landing distance
Ceiling
Fuel economy
Stability
Vso
Stall speed with flaps - 49 mph
Vs1
Clean configuration - 57mph
Va
Maneuvering Speed - 112mph
Vy
Rate of climb - distance over time. 90mph
Vx
Angle of Climb - 78. Will increase with altitude
Vfe
Maximum flap extension speed top of white arc, 100 mph (54-100)
Vno
Normal operating speed - 145mph
Vne
Never Exceed - 182 mph
Minimum Sink Speed
Less distance travelled but more time in the air. Not published, but few knots lower than best glide speed.
Types of Airspeed
- IAS - shown on the airspeed indicator
- True airspeed - speed relative to air (depends on temperature, altitude). As climb, TAS is higher than IAS because less air molecules to go through the pitot tube
- Ground speed - TAS accounted for wind
- Calibrated airspeed - IAS corrected for instrument and position errors. Difference greatest at low airspeeds with high nose pitch attitudes. Airspeed correction table in POH.
How is the electrical system protected?
Circuit breakers protect from an overload - same function as fuses but CBS can be reset.
What uses electricity?
Radio
Avionics
Fuel gauges
Lights
Flaps
5 basic functions of aircraft engine oil
Lubricates the engine’s moving parts
Cools by reducing friction
Removes (absorbs) heat
Seals the cylinders walls and pistons
Cleans - carries off particles and other contaminants
What are some of the main causes of detonation?
High manifold pressure with low RPM
Using a lower grade fuel than approved
Extended ground operations or long steep climb
High power while lean
What to do if detonation is expected?
Enrichen mixture
Reduce angle of climb
Ensure proper grade of fuel is used
Types of Drag
Induced - byproduct of lift. As lift increases, the lift vector tilts backwards. Angle of tilt is induced drag.
Parasitic - caused by friction of the aircraft with the wind.
1. Skin Friction - aircraft surface is rough that interrupts the smooth laminar airflow. Rivets, dirt, bugs.
2. Form Drag - shape of the aircraft. Wings, struts, antennas, landing gear.
3. Interference - interrupted airflows at fuselage and components (wing, landing gear). Interrupts smooth airflow, creating drag treating than form drag alone. Minimized with fairings.
What is best Vg?
Where induced and parasitic drag meet.
What is the camber line?
Middle of airfoil, from leading edge to tip. Wings with more curved airfoils have longer camber line.
Increases when deflect flaps. Increased camber = increased lift
