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This paper presents the composite exceedance method as an alternative to the more costly broadband power spectral density (PSD) analysis which is the standard method of acoustic signature analysis for rotating machinery. The composite exceedance is superior to the PSD analysis in that the computational procedure is straightforward and effective without the use of Fourier Transforms and, therefore, lends itself to simple programming, and the information extracted from the vibration data is represented in one master plot, permitting direct evaluation of all g peak levels encountered in terms of the number of occurrences above which they exceed a given level of acceleration. The sensitivity of anomaly detection by the proposed method has been demonstrated in a number of actual cases, one of which is discussed. The data collection methodology and philosophy of the method as they relate to narrow-band Gaussian random processes are also considered.

A unique propulsion system is being developed for the Space Shuttle Orbiter utilizing airbreathing engines to provide a means for horizontal flight testing and ferrying the Orbiter within the contiguous United States. Primarily, the NASA was concerned with ferrying the Orbiter from manufacturing site to launch site, but it was also recognized that on some occasions weather conditions or other emergency situations might dictate landing at alternate sites when returning from space missions. These situations would also require subsequent takeoff and ferry to a launch site. To fulfill these objectives, certain ground rules and criteria were selected, consisting primarily of takeoff capability on a hot day from a runway 10,000 feet in length, a 423 nautical mile minimum cruise range, engine out cruise ceiling of 10,000 feet, the use of existing engines, and an installation that was easily attached and removed from the Orbiter vehicle.

The Techroll joint is a constant-volume, fluid-filled bearing configured with a pair of rolling convolutes that permits omniaxis deflection of a solid rocket motor nozzle. The fluid-filled bearing is pressurized by nozzle ejection loads and serves as both the movable nozzle bearing and nozzle seal. The Techroll seal is made of a fabric-reinforced elastomeric composite material and does not require complex manufacturing processes or tight tolerances. The Techroll joint has undergone development under U.S. Air Force, Navy, and Army funding and has been demonstrated on six separate contracts involving 12 different designs. This paper introduces the concept, presents four of the designs, and summarizes the performance characteristics of seven designs.

A special subscale, pintle-mounted gas generator was developed by the Army Advanced Ballistic Missile Defense Agency. It was used to comparatively evaluate the thrust vector control systems which might be used in conjunction with pintle-controlled interceptor motors. The two thrust vector control systems which have been evaluated to date are: the Gimballed, Supersonic Splitline Thrust Vector Control System and the Techroll Movable Nozzle Thrust Vector Control System. These evaluations were carried out under simulated altitude conditions with the gas generator operating in a boost and a sustain mode as part of the duty cycle. This paper will discuss the design of this Thrust Vector Control Gas Generator, motor fabrication, its multiple ignition system, the thrust vector control systems, test objectives, test procedures, and test results.

Apollo 17 ended the most successful application of rocket propulsion systems in man's history. A total of 23 developmental and manned operational flights were made. Seven hundred and sixty-three spacecraft rocket engines were flown in the program. Over 6 h of manned rocket flights were logged by the spacecraft propulsion systems and approximately one million rocket engine firings were made. One engine failure was encountered on an early unmanned flight as a result of a failure in the guidance programmer which caused the engine to operate in a manner known to cause failures. Numerous operational problems and malfunctions were observed; however, system and component redundancy prevented loss of mission objectives and never jeopardized crew safety. Performance of all systems was usually nominal and most problems were merely nuisances. This paper will present some highlights of Apollo propulsion performance and will provide a bibliography of all flight results.

A reverberant acoustic field is frequently used in ground testing when it is desired to generate a spacecraft vibration environment similar to that encountered in flight. The sound-pressure level specified to accomplish this is usually the same as the maximum expected flight fluctuating pressure level. Experience has shown this to be an inadequate way to specify reverberant ground test levels because of basic differences in the characteristics of the reverberant and flight fluctuating pressure fields. This paper reviews pertinent information on this subject that has recently been obtained from large upperstage space vehicles.

The need for evaluating and optimizing airframes of advanced aircraft configurations with exceptional speed and accuracy has resulted in the development of highly sophisticated computerized techniques. Sensitivity of these programs to advanced materials, construction types, aeroelasticity, structural dynamics, configuration geometry, airloads, missions, and performance has all but obsoleted the statistical approach to the problem solution. The competitive nature of the field has also placed unusually severe demands on calendar time available for such evaluations. This has resulted in the development of integrated analytical computer programs that have the required sensitivity and rapid turnaround time to face the competitive nature of today's environment.

A study is made in this paper of the fundamental requirements and methods associated with providing uncompromised air freshness, temperature conditioning, and humidity comfort for the passengers and crew of a typical large pressurized transport airplane, such as the Douglas DC-6, for flight under 30,000 feet. Investigation is made of the advisability of reclamation of cabin air through recirculation or by the use of counter-odorants. Special emphasis is given to the investigation and analysis of cabin air humidities. Air conditioning design recommendations for transport aircraft are made in the paper based on the charts and tables developed.