IAF-00-V . 4 . 01 NASA ' s Hyper-X Program
This paper provides an overview of the objectives and status of the Hyper-X program which is tailored to move hypersonic, airbreathing vehicle technology from the laboratory environment to the flight environment, the last stage preceding prototype development. The first Hyper-X research vehicle (HXRV), designated X-43, is being prepared at the Dryden Flight Research Center for flight at Mach 7 in the near future. In addition, the associated booster and vehicle-to-booster adapter are being prepared for flight and flight test preparations are well underway. Extensive risk reduction activities for the first flight and non-recurring design for the Mach 10 X-43 (3rd flight) are nearing completion. The Mach 7 flight of the X-43 will be the first flight of an airframe-integrated scramjet-powered vehicle.
Aeronautical Facilities Catalogue. Volume 1: Wind Tunnels
Domestic and foreign wind tunnel facilities are enumerated and their technical parameters are described. Data pertinent to managers and engineers are presented. Facilities judged comparable in testing capability are noted and grouped together. Several comprehensive cross-indexes and charts are included.
A Parallel Approach to Integrated Multi-Gbit/s Communication over Multiwavelength Optical
process to open up all three fundamental bottlenecks. For reasons discussed in the dissertation, a direct extension of the standard, vertically-oriented OSI model to a multigigabit optical network environment may not be suitable. Furthermore, the design follows new concepts in opening up the electro-optic and service bottlenecks. A new WDM architecture is used that is based on the Wavelength-Dedicated-to-Application (WDA) concept. The network has an architecture structured to a multiclass network model with a pipelined model used for communication. A coarse WDM is used to open up the electro-optic bottleneck. Specific time-synchronous channels, placed in different wavelengths, are dedicated to different applications and control mechanisms according to their traffic characteristics, e.g., CBR and/or VBR isochronous traffic, computer data transfer (with focus on latency), application-specific control mechanisms for media access, error handling, flow control, etc. We use separation of different user-traffic, and of information traffic from control traffic, in order to open up the service bottleneck. Furthermore, separate, simplified and application-oriented protocols supporting both packetand circuit-switching are used to open up the processing bottleneck. An original solution is advanced for the problem of multiple data stream (low-level) synchronization in a WDA network. It includes specific solutions for point-to-point transmission, bit synchronization (jitter compensation) and slot synchronization, as well as proper algorithms for frame synchronization. Detailed theoretical analysis and performance evaluation are provided for the study of typical cases, which include one, or multiple, data channel(s) and one, or multiple, control channel(s), all placed in different wavelengths on the same fiber. Discussion of basic implementation issues is provided as well. In order to provide bounded delay and jitter requirements for loss-free nonisochronous traffic, we suggest a new approach for congestion control and bandwidth allocation, which is of type Rate Controlled Admission with Priority Scheduling Service. We call this Dynamic Time Sharing (DTS). This approach is based on guaranteeing specific traffic parameters (bandwidth requirements) through a policer/shaper unit, and then optimizing the bandwidth assignment, within the network, for specific parameters of interest (such as delay or jitter, and loss). The optimization process is based on the parameters guaranteed by the shaper. A batch admission policy is used at the edges of the network according to a specific framing strategy to follow the traffic (peak bandwidth) characteristics of different traffic subclasses. On the other hand, another framing (congestion control) strategy is used within the network, which is based on different (delay/loss) requirements of the traffic classes. Proper management of bandwidth and buffer resources is provided in every (switch) node of the network, such as to guarantee the diverse performance of interest, regardless of traffic statistics, network size and transmission speed. The performance results clearly indicate the feasibility of this new concept as a candidate for the future multi-gigabit communication over multiwavelength optical networks. Such an architectural model offers the choice of performance restricted by optics, and less by electronics or processing. It offers the choice of reducing the latency in communication to limits that are commensurable with those given by the propagation delay on fiber. Real-time services, with specified delay and bandwidth requirements, can be easily provided. Simple and low-processing application-oriented protocols are used, with no interference among user-traffic classes. It is therefore very suitable for service integration, irrespective of traffic and network conditions. There is no need for technological breakthroughs, no need for wavelength agility, and LAN environments can be easily developed that are capable of supporting large number of supercomputers. The disadvantage of this approach is given mainly by the hardware replication, which is needed in every node for each traffic class.