Inverse simulation is a technique whereby the control actions required for a modelled vehicle to fly a specified manoeuvre can be established. In this paper the general concepts of inverse simulation are introduced, and an algorithm designed specifically to achieve inverse simulation of a single main and tail rotor helicopter is presented. An important element of an inverse simulation is the de...

This study aims to determine change in optimal locations of dual trailing-edge flaps for various thrust coefficient to solidity (Ct /σ) ratios of helicopter to achieve minimum hub vibration levels, with low penalty in terms of required trailing-edge flap control power. Polynomial response functions are used to approximate hub vibration and flap power objective functions. Single objective and mu...

Helicopter operations imply Whole-Body Vibration (WBV), primarily due to the motions of the main rotor system. Health effects of WBV in general have primarily been related to the spine and it's related structures. However, many other effects are present, some of them having potential health implications while others may affect safety by acting on the human operator's physiology. METHODS AND DIS...

Six well known gear metrics were computed from vibration signals previously recorded from an OH-58C helicopter under controlled flight conditions. For the pinion gear studied, an optimal number of rotations was found for the average. Stationarity decreased as the number of rotations increased. It is conjectured that the dynamic environment of the helicopter is the primary contributor to the dec...

The basic features in the interaction of a rotor wake with a wing in low-speed forward flight are studied using low-speed wind tunnel experiments. The configuration captures several of the aerodynamic interactions in the tiltrotor transition phase, and during wake/empennage interactions. Previous work showed that the pressure field on the wing surface below the rotor is dominated by n-per-rev "...

This paper presents a multi-agent search technique to design an optimal composite box-beam helicopter rotor blade. The search technique is called particle swarm optimization (‘inspired by the choreography of a bird flock’). The continuous geometry parameters (cross-sectional dimensions) and discrete ply angles of the box-beams are considered as design variables. The objective of the design prob...

Structural damage in materials evolves over time due to growth of fatigue cracks in homogenous materials and a complicated process of matrix cracking, delamination, fiber breakage and fiber matrix debonding in composite materials. In this study, a finite element model of the helicopter rotor blade is used to analyze the effect of damage growth on the modal frequencies. Phenomenological models o...

This paper presents results from the attitude control optimization for a small-scale helicopter by using an identified model of the vehicle dynamics that explicitly accounts for the coupled rotor/stabilizer/fuselage (r/s/f) dynamics. The accuracy of the model is verified by showing that it successfully predicts the performance of the control system currently used for Carnegie Mellon’s autonomou...

A heavy lift slowed-rotor tandem compound helicopter was designed as a part of the NASA Heavy Lift Rotorcraft Systems Investigation. The vehicle is required to carry 120 passengers over a range of 1200 nautical miles and cruise at 350 knots at an altitude of 30,000 ft. The basic size of the helicopter was determined by the U.S. Army Aeroflightdynamics Directorate’s design code RC. Then performa...

The work reported in this paper is aimed at designing a velocity/altitude and position controllers for the unmanned helicopter APID MK-III by Scandicraft AB in Sweden. The controllers are able of regulating high velocities via stabilization of the attitude angles within much larger ranges than currently available. We use a novel approach to the design consisting of two steps: rst, a gradient de...