Refine Your Search

Topic

Author

Affiliation

Search Results

Technical Paper

Electrical Power System Architectures for Future Aerospace Vehicles

1988-10-01
881412
Electrical power system architectures and design concerns for future Mach 3 to 25 aerospace vehicles are discussed. Three conceptual electrical power system architectures were developed to meet the requirements of a future aerospace vehicle. Architectures developed include a hybrid 270 Vdc/115 Vac four- bus architecture, a 270 Vdc four-bus architecture, and a 115 Vac four-bus architecture. The vehicle requirements chosen for this study include electrically driven flight control surface actuators and main engine propellant boost pumps, A trade study was performed to determine the optimum distribution architecture based on total system weight, compatibility of the system with the vehicle loads, component availability, corona susceptibility, development risk, and personnel safety. The trade study identified the hybrid 270 Vdc/115 Vac four bus architecture as the optimum configuration for the given requirements.
Technical Paper

Overview on the Evolution of Aircraft Battery Systems Used in Air Force Aircraft

1988-10-01
881411
The proposed paper will focus on the Air Force's effort that will increase reliability and maintainability and substantially decrease, if not eliminate, the cost of maintaining aircraft battery systems. This effort is recognized throughout the military services, (Army, Navy, and Air Force), and with most of the major aircraft battery manufacturers as the Tiger Team. The Tiger Team began approximately two years ago. The goal of this team is to eliminate battery flight line maintenance shops. The battery that is currently used in most aircraft, vented nickel-cadmium, requires frequent flight line maintenance. This procedure is very costly and time consuming. The proposed paper will overview battery technologies that are being considered for a replacement of the conventional vented nickel-cadmium aircraft battery technology. This overview will also look briefly at the history of aircraft battery systems and how aircraft battery systems arrived at their current status.
Technical Paper

Prop-Fan Structural Results From PTA Tests

1988-10-01
881418
Prop-Fan propulsion systems have progressed from concepts and models to large scale aircraft/propulsion system integration tests. During the Prop-Fan Test Assessment program a nine foot diameter Prop-Fan driven by a gas turbine engine was mounted on the port wing of a test bed aircraft. The goals of this program were to demonstrate the Prop-Fan system while obtaining baseline structural and acoustic data during flight and ground operation to advance the understanding of a Prop-Fan in large scale. This paper presents the major findings of the structural portion of the test program. Blade dynamic strain measurements taken over a wide range of ground and flight operating conditions including the effect of nacelle tilt angle are presented. The flight test results establish trends in blade dynamic response with aircraft operating conditions and these trends are compared to Prop-Fan forced response predictions.
Technical Paper

Use of Color Displays in the A320 Cockpit

1988-10-01
881416
The Airbus A320 is the first commercial aircraft to provide a color display unit as the primary interface between the flight crew and the flight management system. In order to obtain maximum information about the flight management data being displayed, specific rules concerning color usage apply. This enables a more manageable operation thus reducing flight crew workload.
Technical Paper

Aircraft Automation with an Electronic Library System

1988-10-01
881415
An Electronic Library System (ELS) is currently being developed for use in commercial aircraft. This system will supplement and eventually replace the conventional paper manuals with electronically stored data. Using advanced technologies of optical disk data storage, high resolution displays and sophisticated software, the ELS will provide a high degree of cockpit automation and added functionality for many avionics applications. Many airline operations will benefit from the cost savings that this system will offer, particularly maintenance operations. This paper will describe some proposed features of the ELS as well as the technology that will be used to implement it.
Technical Paper

High Reliability Aircraft Generator System

1988-10-01
881414
An alternative approach for producing variable speed constant frequency (VSCF) constant voltage power is the use of a resonant link power system. This system uses a permanent magnet (PM) generator and a resonant link solid state power converter. An electrically isolated PM generator may also be required for protection depending upon the final control topology. The use of a resonant link allows bi-directional power flow for engine start capability. Also, the resonant link allows the power semiconductor devices to be switched during the high frequency link zero crossings to reduce device stresses and improve reliability. The resonant link VSCF system is under investigation by the GE Corporate Research and Development group under contract #F33615-87-C-2806 to the Air Force.
Technical Paper

High Angle of Attack Aerodynamics of Excitation of the Locked Leeside Vortex

1988-10-01
881424
The control of flow over a multi-component wing at large incidence has been investigated. At large incidence angles flow over, the wing upper surface becomes fully separated. The wing geometry was considered critical in management of flow energy through organization of vorticity and controlling its shedding on the wing upper surface. A flat plate wing, with the planform of a F-15 wing, was reconfigured to accommodate the locked vortex. Span-wise blowing was used to initiate and/or to increase the strength of the vortical flow. It was anticipated that in this manner an excited, stable, concentrated and strong vortex would be created on the wing. Using flow visualization as well as force measurements it was found that the presence of the locked vortex favorably changed the flow pattern over the wing. Force measurements indicated moderate improvements on most configurations. One configuration, however, demonstrated significant improvements.
Technical Paper

Low-Speed Vortical Flow over a 5-Degree Cone with Tip Geometry Variations

1988-10-01
881422
An experiment was conducted to measure the surface pressures and sectional side forces on a 5° cone with three nose tips. The nose tips included a sharp, an 8.7% blunt, and a 17.5% blunt nose tip. Rings of pressure orifices were located at 40% and 80% of the model length and the model was rolled from ±180° in 9° increments to determine roll dependence. The sectional side force data for the sharp cone showed a strong dependence on the roll orientation of the model. The blunt nose cone configurations also showed a dependence on roll orientation. The blunt nose configurations were effective in reducing the sectional side force for angles of attack up to 25°. However, at angles of attack greater than 35°, the reduction was no longer significant. Pressure distributions for three angles of attack are presented to highlight details of the flow when: vortex asymmetries are just beginning; the vortices are in a steady asymmetric state; a vortex has shed between the 40% and 80% stations.
Technical Paper

Wind-Tunnel Investigation of the Forebody Aerodynamics of a Vortex-Lift Fighter Configuration at High Angles of Attack

1988-10-01
881419
Abstract Results of a recent low-speed wind-tunnel investigation conducted to define the forebody flow on a 16% scale model of the NASA High Angle-of-Attack Research Vehicle (HARV), an F-18 configuration, are presented with analysis. Measurements include force and moment data, oil-flow visualizations, and surface pressure data taken at angles of attack near and above maximum lift (36° to 52°) at a Reynolds number of one million based on mean aerodynamic chord. The results presented identify the key flow-field features on the forebody including the wing-body strake.
X