A survey of dynamic analysis methods for airframe-flight control design

: The results of a flight test program to investigate longitudinal short period frequency requirements and PIO (pilot-induced oscillation) tendencies are presented and discussed. Short period frequency requirements were investigated with a damping ratio of approximately 0.7 at three fixed values. PIO tendencies were investigated with various values. The feel system dynamic characteristics were held essentially constant throughout the program. A variable stability T-33 airplane was used as an in-flight simulator. Each configuration was evaluated as a fighter in 'up and away' flight. The evaluation pilots commented on each configuration and rated each numerically. An analysis of pilot ratings and pilot comments was made, and these in turn were related to various handling qualities parameters. In the analysis and interpretation of the handling qualities results, feel system dynamics and pilot-selected stick force gradients were also important considerations.

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Flight investigation of longitudinal short period frequency requirements and pio tendencies

T purpose of this Survey is to review technical fields that are of primary concern to the theoretical design of flight control systems, i.e., systems for the control of attitude of aerospace vehicles. Three major areas have been selected, description of vehicle dynamics, design criteria, and control theory. The literature in the first and last of these fields in quite extensive. However, the second field, design criteria, has received a very small amount of attention, despite its obvious importance. The available information is reviewed and several suggestions are offered as to directions of further work. Prediction of aerodynamic forces and moments is not considered. In preparing this Survey, several thousand books, reports, and journal articles were reviewed. Space does not permit mention here of more than a fraction of this work, nor would so great a volume of material serve the reader well. Accordingly, a selection has been made based on the author's prejudices, but with preference for references with one or more of the following attributes, listed in no special order: 1) clarity of presentation, 2) comprehensiveness (survey articles are favored), 3) recent date, 4) ready availability (company reports are discriminated against), 5) originality, and 6) importance of the work in development of the field. Many worthwhile papers had to be omitted. An earlier work along the same lines has a somewhat broader scope than the present survey and about twice as many references.

Survey of dynamic analysis methods for flight control design.

A robust controller design strategy is presented for systems, the parameters of which are affected dominantly by a few unknown physical quantities The use of the functional dependence of the model parameters on these physical quantities results in an accurate description of the model uncertainty space This potentially may lead to a better tradeoff between performance and robustness The proposed procedure for modeling such uncertain systems relies on the linear-fractional-transformation algebra and reduction of the uncertainty block dimension The resulting model can be used for control synthesis using any robust control design technique In this work fi synthesis was adopted since it best fits the structured uncertainty model obtained An example presents a controller design for an unmanned flight vehicle, the model parameters of which depend on the unknown mass of its payload The aircraft equations are derived, and a p, controller is synthesized The controller is compared to other control methods, and its advantages are demonstrated

Robust control design strategy with parameter-dominated uncertainty

Handling qualities are without doubt one of the primary objectives of the design of modem rotary-wing aircraft, where improved handling qualities increase mission effectiveness and flight safety, and reduce pilot workload. This dissertation provides results of an assessment of gyroplane handling qualities using flight testing and simulation techniques. Since at the time of writing, there are no direct handling qualities requirements and criteria developed for light gyroplanes anywhere in the world, objective handling qualities of the G-UNIV research gyroplane are estimated using criteria from numerous fixed and rotary wing aircraft specifications. To obtain subjective handling qualities gyroplane test manoeuvres must be designed. In this thesis inverse simulation is proposed as a preliminary tool in designing gyroplane manoeuvres. A high fidelity, individual blade/blade element coupled rotor-fuselage mathematical model of a gyroplane, GSIM is developed and successfully coupled with a generic inverse simulation algorithm GENISA to form an inverse simulation package GENISA/GSIM. Two gyroplane manoeuvres, slalom and acceleration-deceleration, are designed based on those from the Aeronautical Design Standard ADS-33E-PRF. A flight test programme for the G-UNIV research gyroplane is conducted to demonstrate the use of the designed gyroplane manoeuvres and obtain subjective handling qualities. Preliminary recommendations are proposed regarding suitability of handling qualities criteria of fixed and rotary wing aircraft. In addition, this dissertation proposes two handling qualities criteria for a light gyroplane, roll quickness and pilot attack criteria for the slalom manoeuvre.

Gyroplane handling qualities assessment using flight testing and simulation techniques

Compliance with current longitudinal handling qualities criteria is not a guaranteed acceptance of vehicle characteristics. Several criteria for satisfactory characteristics resulting from handling qualities investigations in simulators and variable-stability airplanes are reviewed; in comparison, these criteria reveal significant areas of disagreement. Further, much of the large-airplane data available that reflect satisfactory characteristics in flight would be judged unacceptable to unsatisfactory from these criteria. Consideration of the piloting technique involved in flightpath control indicates the significance of the parameters La/ 15 g/rad also yield good agreement when mapped onto the nza/0}n vs f plane. These three parameters—nza, La/<j3n, and nza/(j}n—-furnish the framework for complete longitudinal handling qualities criteria. These criteria provide the basis for an over-all correlation of pilot opinion data from four sources: 1) airplane characteristics from fixed-base and inflight simulation of airplanes exhibiting high natural short-period frequency, 2) flight experience of commercial jet transports, 3) fixed-base simulation of the B-52, and 4) inflight simulation of very large transports with low natural short-period frequency on the Boeing 367-80 jet transport prototype.

W. M. Gertsen

Papers

Longitudinal handling qualities criteria - An evaluation.

Longitudinal handling qualities criteria - An evaluation