H3-2b Flight, VRS (2.19-2-26) Flashcards
2-19 airflow in for flight 2-20 symmetry of lift 2-21 translation lift 2-22 effective translation lift ETL 2-22 translational thrust 2-23 induced Flow 2-24 transverse flow effect 2-24 sideward Flight 2-24 rearward Flight 2-24 turning Flight 2-25 auto rotation 2-25 vertical auto rotation 2-26 Autorotation (Forward Flight) (47 cards)
2-20 What is retreating blade stall? Because high___ ___ and high ___ __ ____ and slow ___ __
At a high forward speed the retreating blade stalls because of high AOA and slow relative wind
Vne
Never exceed speed
2-20 What is blowback? What causes it?
When transitioning TO FORWARD FLIGHT the nose may PITCH UP due to increased efficiency in translational lift
2-21 Translational Lift
Improved rotor efficiency resulting from directional flight
2-23 What is (TFE) Transverse Flow effect? At what speeds? And causes what 2 things.
-In forward flight, air passing through the rear portion of the rotor disk has a greater induced flow that the air passing through the forward portion.
-Noticeable between 12-15 knots
-Causes vibrations,
AND a gyroscopic precession right roll.
-Compensated by cyclic to the left
2-22 Effective Translational Lift (ETL)
-about 16 - 24 knots
-Main Rotor System outruns dirty air and vortexes
2-22 Translational Thrust
-Tail rotor clean air from hover to forward flight.
-More lift more yaw power
2-22 What effect does translational thrust have on yaw?
-Compensate by___ (AOA)…
-What will bring the nose to more level altitude
-Less turbulent air causes improved efficiency,
-helps anti-torque thrust, causing the nose to yaw left.
-Decrease the AOA and the tail router blades to apply right anti-torque
-Horizontal stabilizers, bring nose to more level altitude,
2-23 How to recognize transverse flow effect
-Increase in vibrations around 12 to 15 kn
2-23 Transverse flow can be produced by what 2 situations?
-forward Flight
-Wind hitting while in Hover
2-23 When does transverse flow effect happen (vibrate) in relation to ETL?
Vibration at airspeed just below ETL on takeoff and after passing through ETL during landing.
H.2-23 list two reasons sideward flight is dangerous
-parasitic drag from the fuselage
-No horizontal stabilizer–* increased altitude will help
2-23 Why does transverse flow effect vibration happen close to the same airspeed as ETL
That is when the greatest lift differential exists between the front and rear portion of the rotor system.
2-24 name a major hazard of rearward flight (2)
-Horizontal stabilizer tilts the tail downward—The rear of most skids is not angled
2-24 Define vertical component of Lyft
Lift Acting upward and opposing weight
2-24 Define horizontal component of Lyft
Lift acting horizontally, opposing inertia (centrifugal force)
2-25 auto rotation is permitted mechanically by
A freewheeling unit
2-25 what does a freewheeling unit do
It’s a special CLUTCH MECHANISM that allows the main rotor to continue turning even when the engine is not running
TFE
Transverse flow effect
3 things needed for VRS
-below ETL
->300 fpt drop
-20-100% power applied
VRS Vuichard recovery (3)
-increase collective
-opposite pedal/torque
-cyclic right
2-26 During Vertical autorotation, what are the names and percentages of the 3 regions
Stall region %25, driving region %45, driven region %30 (Propeller region)
TAF
Total aerodynamic force
2-26 in Vertical autorotation, the 2 points of equilibrium on the rotor blade are aligned with the ____ __ ____?
Lift and drag are produced but what is the outcome?
-Axis of rotation
-neither acceleration nor deceleration
