The Development Of Microcomputer Codes For Studying The Flight Dynamics And Performance Of Helicopters

A sequence of computer codes for predicting the dynamic behavior of a single rotor/tail rotor helicopter is described. There are four basic codes described, each of which can be run on current microcomputers. A static trim program forms the starting point for a dynamic program by calculating the control angles and the helicopter angle of attack. Classical closed-form solutions for the flapping of a rigid, articulated rotor are assumed. A dynamic program then numerically integrates the Euler equations of motion to fly a prescribed maneuver. Feedback is provided to the longitudinal and lateral cyclic pitch and to the tail rotor collective pitch for stability augmentation and in order to fly the maneuver. A third program determines stability derivatives which are used in the fourth program which analyzes the stability of the helicopter. Linearizing the longitudinal and lateral equations, this program generates root loci as a function of stabilizing and control feedback gains. All of the programs include possible contributions from a stub wing and a horizontal tail with an incidence angle which can be linked to the longitudinal cyclic pitch. Reasonable agreement is found for comparisons of predicted results with flight tests simulating the launching of a ballistic rocket.