A new geometric representation algorithm is used which uses the function / form function transformation (CST) to generate aerodynamic profile coordinates. With this approach, the shape of the aerodynamic profile is considered in terms of design variables. The optimization process is built by integrating several programs developed by the author. Design variables include torsion, conical relationship, cone initiation point, shovel root chord, and coefficients of the aerodynamic profile distribution function. The aerodynamic constraints consist of limits of the available power in fixed flight and in flight. The fit condition must be attainable. This document considers the configuration of the rotor blade for the in-flight flight condition only, so that the required power in fixed flight is chosen as the objective function of the optimization problem. The sensitivity analysis of each design variable shows that the shape of the aerodynamic profile plays an important role in the performance of the rotor. The optimum rotor blade reduces the required idle power by 7.4% and increases the figure of merit by 6.5%, which is a good improvement for the design of the rotor blade.
A main rotor of a helicopter or rotor system is the combination of several rotating wings (rotor blades) and a control system that generates the aerodynamic lifting force that supports the weight of the helicopter and the thrust that counteracts the aerodynamic resistance in flight forward. Each main rotor is mounted on a vertical mast over the top of the helicopter, as opposed to a helicopter tail rotor, which is connected through a combination of transmission shaft (s) and gearboxes along the feather tail. The pitch of the blade is typically controlled by an oscillating plate connected to the helicopter's flight controls. Helicopters are an example of rotary aircraft (helicopter). The name is derived from the Greek words helix, helik-, which means spiral; and pteron which means wing.
Design Overview
The rotor of the helicopter is driven by the motor, through the transmission, to the rotating mast. The mast is a cylindrical metal shaft that extends upward from and is driven by the transmission. At the top of the mast is the fixing point for the rotor blades called the hub. The rotor blades are then fixed to the hub, and the hub can have 10-20 times the blade resistance. The main rotor systems are classified according to how the main rotor blades are attached and move relative to the main rotor hub. There are three basic classifications: hinged, swinging and fully articulated, although some modern rotor systems use a combination of these classifications. A rotor is a finely tuned rotating mass, and different subtle adjustments reduce vibrations at different speeds. The rotors are designed to operate at a fixed RPM (within a narrow range of a small percentage), but some experimental aircraft used variable speed rotors.
Unlike the small diameter fans used in turbofan engines, the main rotor of a helicopter has a large diameter that allows it to accelerate a large volume of air. This allows a lower lower discharge rate for a given amount of thrust. Since it is more efficient at low speeds to accelerate a large amount of air to a degree lower than a small amount of air to a large extent, a low disc load (thrust per disc area) greatly increases the energy efficiency of the aircraft and this reduces fuel use and allows a reasonable range. The efficiency of the hover ("figure of merit") [19] of a typical helicopter is about 60%. The third internal length of a rotor blade contributes very little to lift due to its low aerodynamic speed.