Hari Muhammad

DEVELOPMENT OF AUTOMATIC FLIGHT CONTROL SYSTEMS FOR WING IN SURFACE EFFECT CRAFT

Abstract This paper will discuss the development of an automatic flight control system of Wing in Surface Effect Craft (WiSE). Since the vehicle must fly at very low altitude to gain an improved lift to drag ratio, the altitude-holding system is designed to hold the desired optimal altitude. The design for the altitude holding system is done by using the classical control law of gain scheduling. The gains of three different altitudes are determined by analysing the root locus diagram. Some simulation results are presented and evaluated in this paper.

Estimation of Lateral/Directional Static Stability Characteristics of a Turboprop Aircraft at one Engine Inoperative Condition

Twin engines turboprop aircraft provides the most beneficial solution to meet the needs of short distance flight due to high fuel efficiency [1]. One of the emergency conditions which has to be considered for this type of the aircraft when one engine is out operating or one engine inoperative because it involves the safety of flight. Furthermore, a safe flight with one engine inoperative is regulated by FAR/CASR Part 25 and has to be complied during certification .Stability and control characteristics of a turboprop aircraft will change significantly if one engine inoperative condition occurs during cruise phase. The rudder and/or aileron deflections to counter the yawing and rolling moments due to the thrust of the operating engine must satisfy. Recognizing the importance of that consideration, this research will estimate the stability and control characteristics of lateral/directional in one engine inoperative condition on new turboprop 80-pax aircraft design concept.This paper presents procedures for estimating the lateral/directional static stability characteristics of a 80-pax turboprop aircraft during the conceptual design phase. The size of the rudder and aileron have to be iterated to fullfil the requirements at a condition when one engine is not operative. The rudder and the aileron deflections are estimated as functions of airspeed, roll angle, side slip angle and thrust setting. It will be shown in this paper that the required rudder deflection as well as aileron deflection can satisfy to balance the forces and moments due to asymmetrical thrust condition and the minimum control speed of the aircraft can be maintained as well.

Numerical Simulation of 2D Flow around Deforming Fish-Like Body

In computational fluid dynamics (CFD), the physical domain is usually discretized by using mesh/grid, cells, nodes or particles generation. Although there are many advantages, these methods are required to have high computational storage/time cost, especially for solving the complex, deforming, and moving flows/bodies. Hence, we developed the vortex-in-cell (VIC) algorithm which is hybrid combination of grid-based and mesh-free method. VIC method, which was originally developed to simulate incompressible single-phase flows, becomes a very promising alternative for simulating complex flows. In addition, to simulate flows over deforming geometries, we utilized an immersed boundary method for enforcing the boundary condition. VIC interpolates the particle strength to an underlying mesh. VIC method has the advantage that the Poisson inversion can be accomplished by Fast Fourier Transform (FFT) techniques, this accelerates the computational time and provides accurate results. Here we consider an anguilliform swimming motion based on lateral displacement of the “backbone” which describes a complex, deforming, and moving body. “Flow over an Impulsively Started Circular Cylinder” problem are also simulated to validate the developed numerical method.

MATHEMATICAL MODELING, SIMULATION AND IDENTIFICATION OF MICRO COAXIAL HELICOPTER

Micro Coaxial Helicopter with compact size and vertical takeoff ability offers a good Micro Aerial Vehicle (MAV) configuration to handle indoor mission such as search, rescue and surveillance. An autonomous MAV helicopter equipped with micro vision devices could provide more information of the scene, in which the human present is risky. Toward an autonomous flight, mathematical model of the helicopter should be obtained before controller design takes place. This paper will discuss the mathematical modelling, simulation and identification of a micro coaxial helicopter. The mathematical model of the micro coaxial helicopter will be presented, in which total forces and moment are expressed as a Taylor series expansion as function of the state and control variables. The mathematical model will be used to simulate the helicopter responses due to control input. The simulation was used to obtain better understanding of the characteristics of the helicopter before flight test program are performed. Flight test program dedicated to identify the parameter of the micro coaxial helicopter have been carried out. The micro coaxial helicopter was instrumented with sensory system to measure some input and output variables. The use of Kalman filter to estimate the state and total least squares to estimate the aerodynamic parameter of micro coaxial helicopter based on the flight test data will be presented. Some identification results and model validation will be given in this paper.

Measurements of flutter derivatives of a bridge deck sectional model

Aeroelastic phenomena should be considered during the design phase of long span bridges. One of the aeroelastic problems is flutter, the dynamic instability that may cause structural failure at a wind speed called the flutter speed. The prediction of flutter speed of a bridge needs a thorough modelling of bridge stiffness, inertias, and especially its unsteady aerodynamic forces. The potential flow theory is not applicable to calculate unsteady aerodynamics of oscillating bridges due to their non-streamlined complex geometry, and the non-avoidable flow separation. For these reasons, a semi empirical model proposed by Scanlan is used to describe unsteady aerodynamic forces on an oscillating bridge deck. In this model, relation between unsteady aerodynamic forces and motion of the bridge is modelled using parameters known as flutter derivatives. The values of flutter derivatives can be identified from the free vibration responses of an elastic bridge at several wind-speeds. This paper presents wind tunnel tests and flutter derivatives identification of a sectional aeroelastic bridge model. Modified Ibrahim Time Domain method was applied to identify the eigenvalues and eigenvectors of the model at each wind speed, from which the flutter derivatives can be calculated. The results show that the measurement procedure is able produce flutter derivatives, which are in good agreement with those obtained by other researchers.