The following abbreviations and symbols are used in articles throughout this website. These are mostly consistent with other helicopter literature.
\(\alpha\) |
angle of attack of the fuselage, rotor plane or a blade section depending on the context |
A | rotor area |
AFCS | automatic flight control system |
\(\beta\) | sideslip angle or blade flapping angle |
\(\beta_C\) | main rotor longitudinal flapping |
\(\beta_S\) | main rotor lateral flapping |
\(C_L\) | roll moment coefficient (\(L/\rho AR(\Omega R)^2\)) |
\(C_M\) | pitch moment coefficient (\(M/\rho A R(\Omega R)^2\)) |
\(C_T\) | rotor thrust coefficient (\(T/\rho A (\Omega R)^2\)) |
CCW | counterclockwise |
CW | clockwise |
D | drag force |
F | force |
GW | gross weight |
\(\lambda\) | rotor inflow ratio ((\(V\sin \alpha + v)/\Omega R\)) |
L | lift force |
LZ | landing zone |
\(\mu\) | rotor advance ratio (\(V\cos \alpha /\Omega R\)) |
\(m\) | mass |
M | pitch moment |
N | yaw moment |
NR | main rotor speed as a percent of nominal speed |
\(\Omega\) | main rotor speed |
\(\phi\) | Euler roll angle |
\(\psi\) | Euler yaw angle |
\(\Psi\) | main rotor azimuth angle |
\(p\) | body roll rate |
\(q\) | body pitch rate |
\(r\) | body yaw rate |
\(\rho\) | air density |
\(r\) | distance of blade section from rotor center |
R | main rotor radius |
SAS | stability augmentation system |
T | rotor thrust |
TAS | true airspeed |
\(\theta\) | Euler pitch angle |
\(\theta_0\) | collective control angle |
\(\theta_C\) | lateral cyclic blade angle |
\(\theta_S\) | longitudinal cyclic blade angle |
\(u\) | body axis forward velocity |
\(v\) | body axis lateral velocity |
\(V\) | total velocity of air relative to helicopter or rotor |
\(v_i\) | rotor-induced velocity |
\(w\) | body axis vertical velocity |
\(y\) | out-of-plane displacement of a blade section |