ISO 5224-2021 pdf free download – Rotorcrafts – Flight dynamics – Vocabulary.
3.6.15
propeller-working state
vertical climb while the rotor disc is moving in the direction of thrust and the airflow is directeddownward through the rotor
Note 1 to entry:The limiting condition for the propeller working state is the static-thrust case, or hovering.3.6.16
vortex ring statesettling with powerpower settling
flight condition at the increased rate of descent in which a helicopter (3.1.2) that is receiving powerfrom its engine(s) loses main rotor(3.2.1) lift (thrust) and subsequently experiences loss of control dueto an increased upward flow of air at the rotor tips and an increased upward flow of air at the bladeroots (3.2.21)
Note 1 to entry:The airflow through the rotor disk recirculates and forms a vertical structure at the blade tips(3.2.20).
3.6.17
windmill brake state
condition in which the rotor derives its energy from the air because the flow is upward through therotor and the slowing of the air as it passes through the rotor disk produces the thrust
Note 1 to entry: The boundary condition between the vortex-ring and windmill-brake states is the conditionwhere the upward flow of air is brought to rest at the rotor disk. This condition of no flow through the disk isreferred to as ideal autorotation (3.8.13).
3.6.18
hover figure of meritFOM
rotor hovering efficiencyrotor thrust efficiency
ratio of the minimum possible power required to hover (ideal power obtained from momentum theory)to the actual power required to hover
3.7 Forces and moments
3.7.1
rotor aerodynamic forceRH
total aerodynamic force acting on main rotor (3.2.1)3.7.2
rotor drag forceH
longitudinal component of rotor aerodynamic force (3.7.1) (along the longitudinal axis of stabilitycoordinate system (3.3.6)) , which is positive rearward
3.7.3
rotor lift forceT
rotor thrust
normal component of rotor aerodynamic force(3.7.1) (along the normal axis of stability coordinate system(3.3.7)), which is positive upward
3.7.4
rotor side forces
transverse component of rotor aerodynamic force (3.7.1) (along the transverse axis of stability coordinatesystem ( 3.3.8))
3.7.5
aerodynamic moment of rotorMH
total aerodynamic moment acting on main rotor (3.2.1)3.7.6
longitudinal aerodynamic moment of rotorMxH
component of rotor aerodynamic force (3.7.1) along the transverse axis of stability coordinate system(3.3.8)
3.7.7
normal aerodynamic moment of rotorMyH
component of rotor aerodynamic force (3.7.1) along the normal axis of stability coordinate system (3.3.7)3.7.8
lateral aerodynamic moment of rotorMzH
component of rotor aerodynamic force (3.7.1) along the longitudinal axis of stability coordinate system(3.3.6)
3.7.9
torque moment of rotorMR
component of rotor aerodynamic force (3.7.1) along the normal axis of stability coordinate system (3.3.7)with negative sign
3.7.10
aerodynamic force coefficient
ratio of aerodynamic forces components along stability coordinate system axis, to value.ISO 5224 pdf download.