Final answer:
Longitudinal stability in aircraft refers to an aircraft's ability to maintain balance along its longitudinal axis, for which the tail plane is essential. In engineering terms, this involves managing aerodynamic forces and ensuring equilibrium. For helicopters, the tail rotor provides necessary counter-thrust to maintain stability.
Step-by-step explanation:
Longitudinal Stability - Tail Plane Characteristics
The subject of longitudinal stability particularly relates to how an aircraft, like a helicopter, maintains its equilibrium along its length or longitudinal axis during flight. The tail plane, or horizontal stabilizer, plays a crucial role in maintaining this stability. Each component of an aircraft is designed specifically to manage different aspects of aerodynamic force. The tail rotor of a helicopter serves a vital function by providing thrust to counteract the torque generated by the main rotor blades. This torque is due to the conservation of angular momentum, which would otherwise cause the helicopter to rotate in the opposite direction of the blades.
Regarding the questions on stability, a round pencil in neutral equilibrium will remain stable relative to displacements perpendicular to its length because it will not roll unless acted upon by an outside force. However, its stability relative to displacements parallel to its length is different; it can easily roll along its length due to the low resistance to such motion. When it comes to suspension bridges, tall towers are necessary to ensure stable equilibrium, as they allow long span lengths and minimize the cables' angles, reducing tension forces and ensuring the stability of the bridge.
The linear speed of a rotor tip can be calculated using the angular velocity if the helicopter is stationary. The blades, functioning like airplane wings, have an adjustable axis to change the angle of attack, affecting lift and drag, critical for the efficient flight of rotary-wing aircraft.