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The results of a study that evaluates the application of hybrid laminar flow control (HLFC) to a long-range, twin-engine subsonic transport aircraft are presented. The study was performed using the Flight Optimization System (FLOPS), a rapid and flexible conceptual design and analysis code. This code is a multidisciplinary system of computer programs for conceptual and preliminary design and evaluation of advanced aircraft concepts. A 300 passenger, twin-engine baseline aircraft was defined for a 6,500 n.mi. design range. All operational and regulatory requirements and constraints, such as fuel reserves, balanced field length and second segment climb are satisfied during the design process. The baseline configuration was sized to account for 50 percent chord laminar flow on the wing upper surface and both surfaces of the horizontal and vertical tails. In addition, the benefits of achieving various amounts of laminar flow on the engine nacelles were also studied.

Laminar flow flight experiments conducted over the past fifty years will be reviewed. The emphasis will be on flight testing conducted under the NASA Laminar Flow Control Program which has been directed towards the most challenging technology application- the high subsonic speed transport. The F111/TACT NLF Glove Flight Test, the F-14 Variable Sweep Transition Flight Experiment, the 757 Wing Noise Survey and NLF Glove Flight Test, the NASA Jetstar Leading Edge Flight Test Program, and the recently initiated Hybrid Laminar Flow Control Flight Experiment will be discussed. To place these recent experiences in perspective, earlier important flight tests will first be reviewed to recall the lessons learned at that time.