Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Current and advanced act control system definition study. Volume 2: Appendices

The current status of the Active Controls Technology (ACT) for the advanced subsonic transport project is investigated through analysis of the systems technical data. Control systems technologies under examination include computerized reliability analysis, pitch axis fly by wire actuator, flaperon actuation system design trade study, control law synthesis and analysis, flutter mode control and gust load alleviation analysis, and implementation of alternative ACT systems. Extensive analysis of the computer techniques involved in each system is included

Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Current and advanced act control system definition study, volume 1

An active controls technology (ACT) system architecture was selected based on current technology system elements and optimal control theory was evaluated for use in analyzing and synthesizing ACT multiple control laws. The system selected employs three redundant computers to implement all of the ACT functions, four redundant smaller computers to implement the crucial pitch-augmented stability function, and a separate maintenance and display computer. The reliability objective of probability of crucial function failure of less than 1 x 10 to the -9th power per flight of 1 hr can be met with current technology system components, if the software is assumed fault free and coverage approaching 1.0 can be provided. The optimal control theory approach to ACT control law synthesis yielded comparable control law performance much more systematically and directly than the classical s-domain approach. The ACT control law performance, although somewhat degraded by the inclusion of representative nonlinearities, remained quite effective. Certain high-frequency gust-load alleviation functions may require increased surface rate capability

Gust Load Alleviation on a Large Blended Wing Body Airliner

This paper investigates the gust load response of a large 750 passenger Blended Wing Body (BWB) airliner for identification of sizing cases for the aircraft structure. Considering manoeuvre load alleviation, gust loads become the dominant sizing factor for the BWB airplane. In order to allow for structural weight saving a Gust Load Alleviation System (GLAS) is designed and evaluated by numeric simulations

Analytical and Experimental Evaluation of Multivariable Stability Margins in Active Flutter Suppression Wind Tunnel Tests

This work addresses control law synthesis for active flutter suppression followed by the design and development of an active flexible wind tunnel model representative of high aspect ratio commercial aircraft. An initial early-design math model of the structural dynamics, unsteady aerodynamics, sensing, and actuation of the system was used to synthesize three control laws that would stabilize the system against flutter over a range of speeds below and above the passive open-loop flutter speed. Three methods for establishing closed-loop robustness measures were used to quantify the robustness of the system based on its initial mathematical model. The system was then tested with these control laws, and their robustness to system variations in the wind tunnel was studied. Such variations included speed as well as gain and phase in the control loops, representing gain and phase uncertainties in the system. This was followed by revisiting the robustness of the control laws with mathematical testing, this time with a more accurate mathematical model of the system. The work highlights the importance of (a) working with as high accuracy as possible math models of the aeroservoelastic system, (b) understanding the key sources and types of uncertainties possible