Propulsion system/flight control integration for supersonic aircraft

Digital integrated control systems are studied. Such systems allow minimization of undesirable interactions while maximizing performance at all flight conditions. One such program is the YF-12 cooperative control program. The existing analog air data computer, autothrottle, autopilot, and inlet control systems are converted to digital systems by using a general purpose airborne computer and interface unit. Existing control laws are programed and tested in flight. Integrated control laws, derived using accurate mathematical models of the airplane and propulsion system in conjunction with modern control techniques, are tested in flight. Analysis indicates that an integrated autothrottle autopilot gives good flight path control and that observers are used to replace failed sensors

YF-12 cooperative airframe/propulsion control system program, volume 1

Several YF-12C airplane analog control systems were converted to a digital system. Included were the air data computer, autopilot, inlet control system, and autothrottle systems. This conversion was performed to allow assessment of digital technology applications to supersonic cruise aircraft. The digital system was composed of a digital computer and specialized interface unit. A large scale mathematical simulation of the airplane was used for integration testing and software checkout

Airbreathing Hypersonic Technology Vision Vehicles and Development Dreams

Significant advancements in hypersonic airbreathing vehicle technology have been made in the country's research centers and industry over the past 40 years. Some of that technology is being validated with the X-43 flight tests. This paper presents an overview of hypersonic airbreathing technology status within the US, and a hypersonic technology development plan. This plan builds on the nation's large investment in hypersonics. This affordable, incremental plan focuses technology development on hypersonic systems, which could be operating by the 2020's

Environmental Adaptations:Encystment and Cyclomorphosis

Stressful environmental conditions generally limit animal survival, growth, and reproduction and may induce dormancy in the form of various resting stages. Tardigrades represent one of a few animal phyla in which different forms of dormancy are frequently encountered. One of these forms, cryptobiosis, a quick response to sudden changes in the environment, has gained a great deal of attention, whereas much less is known of the slower emerging form of dormancy, diapause. In this review we present the current knowledge of diapause in tardigrades. Diapause in tardigrades, represented by encystement and cyclomorphosis, is likely controlled by exogenous stimuli, such as temperature and oxygen tension, and perhaps also by endogenous stimuli. These stimuli initiate and direct successive phases of deep morphological transformations within the individual. Encystment is characterized by tardigrades that lie dormant\u2014in diapause\u2014within retained cuticular coats (exuvia). The ability to form cysts is likely widespread but presently only confirmed for a limited number of species. In tardigrades, cyclomorphosis was first reported as a characteristic of the marine eutardigrade genus Halobiotus. This phenomenon is characterized by pronounced seasonal morphological changes and in Halobiotus involves stages with an extra protecting cuticle. Cyst formation in moss-dwelling limnic species may also occur as part of a seasonal cyclic event and can thus be viewed as part of a cyclomorphosis. Therefore, whereas diapause generally seems to be an optional response to environmental changes, it may also be an obligate part of the life cycle. The evolution of encystment and cyclomorphosis finds its starting point in the molting process. Both phenomena represent an adaptation to environmental constraints. Notably, the evolution of diapause is not necessarily an alternative to cryptobiosis, and some tardigrades may enter both forms of dormancy. The simultaneous occurrence of several adaptive strategies within tardigrades has largely increased the resistance of these enigmatic animals toward extreme environmental stress