Flash Cards
(93 cards)
What is cold soaking?
When cold fuel in the wings travels somewhere warm and humid, moisture builds on the wing and freezes
Dihedral
Wings that angle upwards in a V shape, more stable than flat
Anhedral
Wings than angle downwards, less stable (shaped like “A” for anhedral”
Slats
Small airfoils on leading edge of wing - help airflow at high AoA (“flaps” on front)
Wash out
When the angle of incidence is greater at the base than the tip (twisted out)
Geometric Pitch
The distance a propeller “should” move forward for one rotation
Wing Planform
The shape of the wing when viewed from above
Slats
Small airfoils on leading edge of wing - these increase camber (“flaps” on front)
Slots
Openings built into leading edge to allow air to pass through at high AoA
Spoiler
Airfoil on top of wing that destroys lift & laminar flow, used after touching down
Winglet
Vertical tip on the end of a wing that cancel vortices & decrease induced drag
Positive Stability
Becomes more and more stable (Ball in bowl)
Neutral Stability
Stays the same when moved (Ball on table)
Negative Stability
Becomes less and less stable (Ball on upside down bowl)
Static Stability
Becomes more stable or less stable in one direction
Dynamic Stability
Becomes more stable or less stable back & forth (overcorrecting)
Frise Ailerons
Help reduces aileron drag and adverse yaw by having the leading edge of the aileron below the trailing edge of the main wing (“Freeze” ailerons freeze the tendency for aileron drag)
Balance Tab
Like a trim tab, but automatically moves opposite the elevator control, think of it as a bit of added automatic trim to help the pilots required pressure
Mass Balance
Mass balances counteract flutter in dynamic controls
Torque
The plane’s tendency to rotate opposite the propeller on the longitudinal axis. Typically the propeller rotates clockwise from the pilots perspective causing the plane to bank and therefore yaw to the left (left turning tendencies!)
Slipstream
The air forced backwards from the propeller in the same direction as the propeller. This “snakes” around the plane, pushing the vertical stabilizer to the right (with a clockwise propeller and from the pilot POV) The plane is aerodynamically adjusted to help minimize this effect at cruise power & attitude, but at high power and low airspeed (climb) this force overpowers the adjustments made creating left yaw, and at a low power and high airspeed (descent) this adjustment is unnecessary, creating the opposite effect (right yaw)
Gyroscopic Effect
When the nose is moved in a specific direction it will turn slightly towards the movement that that side is moving towards. So if the propeller is spinning clockwise and the nose of the plane moves up, it will move slightly to the right, if it moves down, look at the direction the bottom of the prop is moving, left, so the nose will move slightly left. According to the law of precession, a force exerted on a spinning mass will cause a reaction 90 degrees along the direction of the rotation
Asymmetric Thrust (P-Factor)
At cruise, both blades of the propeller are taking the same “bite” of air (angle of attack), but when pitching up suddenly, the angle of attack of the right side increases while the left side decreases, causing more thrust on the right side causing a left yaw. (Look at a model propeller and pitch it up and down to understand) Changing this pitch downwards has the opposite effect (right yaw)
Variable Pitch Propeller
When climbing, a smaller propeller AoA (fine pitch) is more efficient, at cruise a larger propeller AoA (coarse pitch) is more efficient. Think of paddling a canoe when you start moving you need small strokes to get going, but once you’re moving big strokes are more efficient. Must know - Variable pitch props are therefore more efficient than fixed props. When a fixed pitch prop plane is pitched up the speed decreases, and the engine has a larger workload but is still putting out the same power, therefore RPM goes down. Variable pitch propellers have something called a “governor” that adjusts the pitch of the blade keeping the same RPM
