Thrust augmentation options for the Beta 2 two-stage-to-orbit vehicle
NASA LeRC is continuing to study propulsion concepts for a horizontal takeoff and landing, fully reusable, two-stage-to-orbit vehicle. This will be capable of launching and returning a 10,000 pound payload to a 100 nautical mile polar orbit using low-risk technology. The vehicle, Beta 2, is a derivative of the USAF/Boeing Beta vehicle which was designed to deliver a 50,000 pound payload to a similar orbit. Beta 2 stages at Mach 6.5 and about 100,000 ft altitude. The propulsion system for the booster is an over/under turbine bypass engine/ramjet configuration. In this paper, several options for thrust augmentation were studied in order to improve the performance of this engine where there was a critical need. Options studies were turbine engine overspeed in the transonic region, water injection at a various turbine engine locations also during the transonic region, and water injection at the turbine engine face during high speed operation. The methodology, constraints, propulsion performance, and mission study results are presented.
Review of High Temperature Ceramics for Aerospace Applications
This paper presents a review of high temperature ceramics research for aerospace applications. Following a brief historical perspective, the paper reviews the effort to toughen ceramics for high temperature structural applications. These include: efforts to toughen zirconia-based ceramics, aluminum oxide, silicon carbide, silicon nitride, molybdenum disilicide and zirconium diborides and carbon-based composites. The development of thermal protection systems is also reviewed within the context of thermal barrier coatings (TBCs) and thermal protection systems for space vehicles. The paper concludes with a final section in which the implications of the results are then discussed for the thermostructural applications of ceramics in aerospace structures.
Complicated One-Dimensional Flows
Abstract : A computational technique for one-dimensional, unsteady flow is presented. The technique emphasizes the role of discontinuities (shocks, contact discontinuities, gradient discontinuities) by treating them explicitly. Points inside regions of continuous flow are treated by a finite difference scheme of second order accuracy. Theoretical and practical arguments to support such an approach are given. The technique allows the computational time to be reduced to a minimum. The accuracy of the results as well as the generality of the program are shown by many applications to one-dimensional and quasi-one- dimensional problems.