Orbit transfer rocket engine technology program: Automated preflight methods concept definition

The possibility of automating preflight engine checkouts on orbit transfer engines is discussed. The minimum requirements in terms of information and processing necessary to assess the engine'e integrity and readiness to perform its mission were first defined. A variety of ways for remotely obtaining that information were generated. The sophistication of these approaches varied from a simple preliminary power up, where the engine is fired up for the first time, to the most advanced approach where the sensor and operational history data system alone indicates engine integrity. The critical issues and benefits of these methods were identified, outlined, and prioritized. The technology readiness of each of these automated preflight methods were then rated on a NASA Office of Exploration scale used for comparing technology options for future mission choices. Finally, estimates were made of the remaining cost to advance the technology for each method to a level where the system validation models have been demonstrated in a simulated environment

Integrated control and health management. Orbit transfer rocket engine technology program

To insure controllability of the baseline design for a 7500 pound thrust, 10:1 throttleable, dual expanded cycle, Hydrogen-Oxygen, orbit transfer rocket engine, an Integrated Controls and Health Monitoring concept was developed. This included: (1) Dynamic engine simulations using a TUTSIM derived computer code; (2) analysis of various control methods; (3) Failure Modes Analysis to identify critical sensors; (4) Survey of applicable sensors technology; and, (5) Study of Health Monitoring philosophies. The engine design was found to be controllable over the full throttling range by using 13 valves, including an oxygen turbine bypass valve to control mixture ratio, and a hydrogen turbine bypass valve, used in conjunction with the oxygen bypass to control thrust. Classic feedback control methods are proposed along with specific requirements for valves, sensors, and the controller. Expanding on the control system, a Health Monitoring system is proposed including suggested computing methods and the following recommended sensors: (1) Fiber optic and silicon bearing deflectometers; (2) Capacitive shaft displacement sensors; and (3) Hot spot thermocouple arrays. Further work is needed to refine and verify the dynamic simulations and control algorithms, to advance sensor capabilities, and to develop the Health Monitoring computational methods

Concept definition study for recovery of tumbling satellites. Volume 1: Executive summary, study results

The first assessment is made of the design requirements and conceptual definition of a front end kit to be transported on the currently defined Orbital Maneuvering Vehicle (OMV) and the Space Transportation System Shuttle Orbiter, to conduct remote, teleoperated recovery of disabled and noncontrollable, tumbling satellites. Previous studies did not quantify the dynamic characteristics of a tumbling satellite, nor did they appear to address the full spectrum of Tumbling Satellite Recovery systems requirements. Both of these aspects are investigated with useful results

A framework of web-based conceptual design

A web-based conceptual design prototype system is presented. The system consists of four parts which interpret on-line sketches as 2D and 3D geometry, extract 3D hierarchical configurations, allow editing of component behaviours, and produce VRML-based behavioural simulations for design verification and web-based application. In the first part, on-line freehand sketched input is interpreted as 2D and 3D geometry, which geometrically represents conceptual design. The system then infers 3D configuration by analysing 3D modelling history. The configuration is described by a parent–child hierarchical relationship and relative positions between two geometric components. The positioning information is computed with respect to the VRML97 specification. In order to verify the conceptual design of a product, the behaviours can be specified interactively on different components. Finally, the system creates VRML97 formatted files for behavioural simulation and collaborative design application over the Internet. The paper gives examples of web-based applications. This work forms a part of a research project into the design and establishing of modular machines for automation manufacture. A consortium of leading automotive companies is collaborating on the research project