Advanced Guidance and Control for Hypersonics and Space Access DRAFT

Advand guidance and control (AG&C) technologies are critical for meeting safety, reliability, and cost requirements for the next generation of reusable launch vehicle (RLV), whether it is fully rocket-powered or has airbreathing components. This becomes clear upon examining the number of expendable launch vehicle failures in the recent past where AG&C technologies could have saved a RLV with the same failure mode, the additional vehicle problems where t h i s technology applies, and the costs and time associated with mission design with or without all these failure issues. The state-of-the-art in guidance and control technology, as well as in computing technology, is at the point where we can look to the possibility of being able to safely return a RLV in any situation where it can physically be recovered. This paper outlines reasons for AWC, current technology efforts, and the additional work needed for making this goal a reality. There are a number of approaches to AG&C that have the potential for achieving the desired goals. For some of these methods, we compare the results of tests designed to demonstrate the achievement of the goals. Tests up to now have been focused on rocket-powered vehicles; application to hypersonic air-breathers is planned. We list the test cases used to demonstrate that the desired results are achieved, briefly describe an automated test scoring method, and display results of the tests. Some ofthe technology components have reached the maturity level where they are ready for application to a new vehicle concept, while others are not as far along in development. Introduction Currentlydemonstrated guidance and control (G&C) technologies are able to automatically fly a reusable launch vehicle to orbit and back to a safe landing. The Space Shuttle has demonstrated this well over 100 times. The guidance and control for the Shuttle is automated except for the approach and landing ~ h a s e ' ~ ~ ~ . Although the astronauts fly the Shuttle during the final phase of flight, an automated system is available4. The Shuttle also has the capability to successfully abort for a number of situations where (single or multiple) main engines are shut down during flight5. Planning for each abort situation (time of engine loss, number of engines lost) requires a significant amount of ground analysis, as would planning for any other failure scenarios, or for new missions. Goals for future reusable launch vehicles include si@cant improvements to vehicle reliability, safety, and cost. Use of AG&C technologies will help make these goals a reality. For defense applications, using mofe adaptable algorithms will allow faster mission planning. Safetv, Reliabilitv, and Cost ImDrovements from Advanced Guidance and Control AG&C technologies can offer the possibility of a safe return under a number of scenarios where it either would not otherwise be available or would require prohibitive amounts of ground analysis to plan each scenario. Among these are: =Abort to landing site with no change in vehicle dynamics *Single engine out *Single engine throttle back *Single engine throttle back followed by same engine out *Multiple engines out at same time *Multiple engines out at different times -For some reason, vehicle performance is off. Could be thrust deficiency, a component that was supposed to jettison but didn't, or somethiig else -Vehicle performance is off but current performance looks okay 1 https://ntrs.nasa.gov/search.jsp?R=20040012611 2017-10-19T15:41:48+00:00Z