ELEMENTS OF THE TRIM EQUATIONS

Main Rotor

The main rotor as the primary source of forces and moments on the helicopter is shown in Figure 8.3 and is described by the following equations for a rotor whose advancing blade is on the right side:

The equations contain several types of terms, as listed in Table 8.1.

TABLE 8.1

Main Rotor Parameters

Term

Symbol

Type

Thrust

TM

unknown

Longitudinal flapping

ai

SM

unknown

Lateral flapping

К

SM

unknown

Sideslip angle

(3

unk. or known

Rotor H-Force

=°M

trim

Rotor torque

Qm

trim

Hub rolling moment stiffness

phys. parameter

Hub pitching moment stiffness

(dM/dat)M

phys. parameter

An example calculation will be done later to illustrate the use of these terms.

FIGURE 8.3 Main Rotor Forces and Moments