CERTAIN PORTIONS ARE ILLEGIBLE , IT IS BEING RELEASED IN THE INTEREST OF MAKING
A review of the factors affecting the helicopter market for the past, present, and future is presented. The trade-offs involving acquisition cost, mission reliability, and life-cycle cost are reviewed, including civil and military aspects. The potential for advanced vehicle configurations with substantial improvements in energy efficiency, operati.ig economics, and characteristics to satisfy the demands of the future market are identified. Advanced propulsion systems required .o support these vehicle configurations are, in turn, discussed, as well as the component technology for the engine systems. Considerations for selection of components in areas of economics and efficiency are presented.
Plasma-sprayed zirconia gas path seal technology: A state-of-the-art review
The benefits derived from application of ceramic materials to high pressure turbine gas path seal components are described and the developmental backgrounds of various approaches are reviewed. The most fully developed approaches are those employing plasma sprayed zirconium oxide as the ceramic material. Prevention of cracking and spalling of the zirconium oxide under cyclic thermal shock conditions imposed by the engine operating cycle is the most immediate problem to be solved before implementation is undertaken. Three promising approaches to improving cyclic thermal shock resistance are described and comparative rig performance of each are reviewed. Advanced concepts showing potential for performance improvements are described.
Research requirements for emergency power to permit hover-one-engine-inoperative helicopter operation
The research and technology demonstration requirements to achieve emergency-power capability for a civil helicopter are documented. The goal for emergency power is the ability to hover with one engine inoperative, transition to minimum-power forward flight, and continue to a safe landing where emergency power may or may not be required. The best method to obtain emergency power is to augment the basic engine power by increasing the engine's speed and turbine-inlet temperature, combined with water-alcohol injection at the engine inlet. Other methods, including turbine boost power and flywheel energy, offer potential for obtaining emergency power for minimum time durations. Costs and schedules are estimated for a research and development program to bring emergency power through a hardware-demonstration test. Interaction of engine emergency-power capability with other helicopter systems is examined.