On the use of controls for subsonic transport performance improvement - Overview and future directions

Glenn Gilyard" and Mart/n Espafia*NASA Dryden Flight Research CenterP.O. Box 273•Edwards, California 93523-0273AbstractIncreasing competition among airline manufacturers and ACEEoperators has highlighted the issue of aircraft efficiency. AbTIFewer aircraft orders have led to an all-out efficiency CCCimprovement effort among the manufacturers to maintainif not increase their share of the shrinking number of air- Ct.craft sales. Aircraft efficiency is important in airline profit- c.g.ability and is key if fuel prices increase from their currentlow. In a continuing effort to improve aircraft efficiency gand develop an optimal performance technology base, HIDECNASA Dryden Flight Research Center developed and LIDflight tested an adaptive performance seeking control sys- LEtem to optimize the quasi-steady-state performance of theF-15 aircraft. The demonstrated technology is equally Mapplicable to transport aircraft although with less improve- MAWmerit. NASA Dryden, in transitioning this technology to MCCtransport aircraft, is specifically exploring the feasibility of PSCapplying adaptive optimal control techniques to perfor-mance optimization of redundant control effectors. A sim- TEulation evaluation of a preliminary control law optimizeswing-aileron camber for minimum net aircraft drag. Twosubmodes are evaluated: one to minimize fuel and theother to maximize velocity. This paper covers the status ofperformance optimization of the current fleet of subsonictransports; available integrated controls technologies arereviewed to define approaches using active controls. Acandidate control law for adaptive performance optimiza-tion is presented along with examples of algorithmoperation.