Algorithms for aircraft trim analysis on ground 13; AIAA-96-350513;

In the analysis of aircraft dynamics far up and13; away flight, the general practice consists of trimming13; the aircraft for a specific maneuvers at a specified13; Altitude and Mach number. In this paper conditions for13; Quasi-steady equilibrium are motivated for aircraft13; dynamics in the ground roll phase. Algorithms for13; implementation of these conditions are also described.13; By use of these algorithms, the locus of trim points is13; obtained for a comprehensive take-off maneuvers of a13; delta wing aircraft beginning with ground roll,13; followed by rotation and ending in lift-off. This result13; is compared with approximate calculations wherein the13; landing gear states are ignored and linear13; aerodynamics is assumed. The exact result is also13; compared with the simulation of the take-off13; maneuvers in a pilot in the loop simulator.13

Application of quantitative measures for analysing aircraft handling qualities

The ease and precision with which pilot is able to handle the designated task determines the aircraft’s handling qualities. Accordingly, the most common methodology for determining aircraft’s handling qualities is through pilot opinions or through questionnaires. These subjective means of analysis is not reliable as the sole source of judgments. Quantitative metrics to analyse the task difficulty based on pilot’s performance, supplemented with subjective decision, can provide better insight into pilot workload levels and in turn the aircraft’s handling qualities. The application of few objective performance measurement techniques to flight data of a high performance fighter aircraft is discussed. Pilot/aircraft’s performance under different configurations is analysed. Analysis results show that pilots usually tend to give more priority to pitch axis in case of dual axis tracking task. And pilots are therefore more aggressive in accomplishing pitch axis tracking task than in roll. Workload assessments were also performed by comparing the results of single axis tracking experiments conducted using a high fidelity flight simulator with the flight data. It is seen that pilot’s aggressiveness levels in controlling the roll control inceptor is significantly less, with improved tracking accuracy when exercised as the primary tas

Landing Gear Modelling For Flight Simulation - Part II

This Report Describes The Landing Gear Modeling Undertaken For Incorporation Into The Six Degree Of Freedom Simulation Software -Class. The General Equations Of Motion For Many Rigid Bodies Interacting With Each Other Are Derived In The Newtonian Formulation. These Results Are Applied To The Derivation Of The Equations Of Motion Of The Telescopic And Articulated Landing Gears.A Complete Analysis Of The Aircraft Dynamics On The Ground Is Presented. Novel Trim Algorithms For Trimming The Aircraft On The Ground Have Been Developed. The Linearized Equations Of Motion On The Ground Are Derived And Many Important Conclusions Are Drawn Regarding The Dynamic Behavior Of Aircraft During Take-Off. The Results Are Directly Relevant To Assessment Of Handling Qualities Of Aircraft In Take-Off In The Preliminary Design Stage. In Conclusion, The Simulation Results Of A Typical Landing And Take-Off Are Presented

Model Based Design of Aerospace Control Systems

"Within the last few decades the microprocessor has developed at a rapid pace creating in its wake a large number of technologies and applications like mobiles, laptops, desktop supercomputers and so on . Aerospace vehicles were and continue to be at the forefront of exploiting these "embedded control systems" . The huge surge in computational power has enabled better modeling and control of complex aerospace systems including hardware and software. At the same time the complexity of onboard software has also grown exponentially. The design of control for aerospace vehicles falls within the area of "Safety critical systems" . In such systems a large part of the design is driven by the need to maintain safety, because the consequences of a failure can be catastrophic . It is not hard to imagine the public outcry when a 300 seater passenger aircraft crashes or a missile falls in the wrong place . In this talk the speaker will explain how model based design of control systems promises to be a powerful tool for safety critical aerospace control systems .

Development of Saras Autopilot

The Automatic Flight Control System (AFCS) for the SARAS aircraft is being designed in collaboration with a private partner. The AFCS provides for Flight Director Guidance function involving a three axis limited authority autopilot with pitch auto trim function. It features13; CAT II approach capability and Control Wheel Steering (CWS). The architecture is fail-safe and extendable to a dual-dual configuration. The autopilot actuators are all electric smart brushless DC motors which engage with the all-mechanical reversible Primary Flight Control System in parallel via individual geared clutches

Modeling And Estimation Of Non-Linear Aerodynamic Coefficient Dependencies For Aero Database Update Of High Performance Aircraft

This Document Describes A Novel Technique For Modeling And Estimation Of Non-Linear Aerodynamic Coefficient Dependencies On Aircraft State And Control Variables . This Is Important From The Point Of View Of Updating The Aerodynamic Database Of Six Dof Simulations Post Flight Test.The Technique Is Validated Using The Six Dof Simulated Data Of An Unstable Aircraft A Augmented With Full Authority Control Laws And Flight Test Data Of Similar Class Of Aircraft

Digital Simulation Model for Turboprop Engine

A comprehensive Turboprop Engine model for digital simulation based on the steady state data and transient characteristics has been proposed for a light transport aircraft. The engine and propeller characteristics have been modeled and implemented in Matlab/Simulink environment. The validation has been carried against the flight data and match is found to be satisfactor

Surface Pressure Estimates for Pitching Aircraft Model at High Angles-of-attack13; 13;

The surface pressure on a pitching delta wing aircraft is estimated from the normal force and the pitching moment characteristics. The pressure model is based on parametrising the surface pressure distribution on a simple delta wing. This model is useful as a first approximation of the load distribution on the aircraft wing. Leeward surface pressure distributions computed by this method are presented

Adaptive control of micro air vehicles

This paper discusses the problems associated with aerodynamic modeling, control and simulation of Micro Air Vehicles (MAVs). It is suggested that MRAC-based adaptive control methods are more suitable than the classical PID and Robust Control methods for MAVs. The salient features of conventional MRAC methods, and two significant and recent variants of these methods – the Modified Reference Model MRAC method and the L1 Adaptive Control method, are briefly described. These adaptive control methods are applied to the roll control of a typical MAV and the results are discussed. The Sliding Mode Control, which can be considered as a robust adaptive control method, is also implemented for pitch rate tracking of the MAV for the sake of comparison

Trends in Simulation Technologies for Aircraft Design

The developments in flight simulation since its inception are reviewed and the latest trends in the use of modeling and simulation for design of flying vehicles are presented. Mathematical model based system development is now universally recognized as a cost effective way to bring new design concepts into reality