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At least 721 records · Page 40

Joint Eglin Acoustics Week 2013 Data Report

Far-field acoustic measurements were obtained for the AH-64D, HH-60M and CV-22B at the Eglin AFB, Test Area C-72, in July/August 2013. The primary purpose for this flight test was to obtain a benchmark database of detailed acoustic source noise characteristics for the aircraft operating at typical mission gross weights over a range of typical mission operating conditions. Data were acquired for a range of steady-state level and descending flight conditions, hover, and a variety of unsteady maneuver conditions. Between 30 and 37 microphones were deployed during these tests. Vehicle position and state data, as well as weather data were acquired simultaneously with the acoustic data. This paper describes the test aircraft, onboard instrumentation, ground instrumentation, and the data acquired. Data from this test are available upon request and review.

Conner, David A.↗

Digital program for calculating static pressure position error

A computer program written to calculate the static pressure position error of airspeed systems contains five separate methods for determining position error, of which the user may select from one to five at a time. The program uses data from both the test aircraft and the ground-based radar to calculate the error. In addition, some of the methods require rawinsonde data or an atmospheric analysis, or both. The program output lists the corrections to Mach number, altitude, and static pressure that are due to position error. Reference values such as angle of attack, angle of sideslip, indicated Mach number, indicated pressure altitude, stagnation pressure, and total temperature are also listed.

Johnson, J. Blair↗

Powered wheels for aircraft

Engineering details, project status, system design and specifications, and test results are presented on a powered-wheel drive system based on the Dynavector rotary actuator. The design and operation of the Dynavector system (with positive displacement very-low-inertia nonrotating vane motor) are reviewed. Feasibility studies, contract data, and findings of braking tests are described. Exploded diagrams of Dynavector details are displayed. Success in using powered wheels in lieu of aircraft main engines for on-ground movements should bring benefits in energy conservation, noise abatement, reduced pollution, and alleviated congestion in the terminal area.

Long, M. J.↗

SAFE - Six axis frequency evaluation of a motion simulator.

SAFE is a digital computer program used to check the response of an aircraft motion simulator. SAFE drives each axis of the simulator near its acceleration, velocity and position limits, recording the simulator motions for comparison with nominal responses. SAFE also drives up to six axes at once to measure the frequency response and noise levels of each axis. Together these two measurements provide a sensitive check of the entire motion system, yet they can be completed in less than ten minutes.

Shirley, R. S.↗

Hover tests of a model H-force rotor

The potential of using tip vanes at the ends of helicopter rotor blades to obtain a controllable H-force is considered. The addition of vanes placed perpendicular to the blade tips can be used to obtain an inplane force. By varying the angle of the vanes, a radial force can be created which can be controllable in azimuth position. Such a force could be used to provide translational motion of the rotor and aircraft without the requirement for rotor tilting. In addition, an H-force generated at high flight speed could be used as a propulsive force in a matter similar to a propeller. The force generated by the vanes could also affect the aircraft's stability characteristics. The H-force could also modify rotor performance in hovering since they could be thought to act as a virtual shroud. Tests were run with a model rotor which has a 6 foot diameter with a 3 inch chord blade. Test data are presented on the effects of various tip-vane configurations on the hovering figure of merit. The extreme sensitivity of the performance to vane arrangement is shown.

Velkoff, H. R.↗

Aerodynamics of the Viggen 37 aircraft. Part 1: General characteristics at low speed

A description of the aerodynamics of the Viggen 37 and its performances, especially at low speeds is presented. The aerodynamic requirements for the design of the Viggen 37 aircraft are given, including the basic design, performance requirement, and aerodynamic characteristics, static and dynamic load test results and flight test results. The Viggen 37 aircraft is designed to be used for air attack, surveillance, pursuit, and training applications. It is shown that this aircraft is suitable for short runways, and has good maneuvering, acceleration, and climbing characteristics. The design objectives for this aircraft were met by utilizing the effect produced by the interference between two triangular wings, positioned in tandem.

Karling, K.↗

Calculating Sonic-Boom Propagation

Nonlinear effects included, enabling more-realistic modeling. Modified Method of Characteristics Sonic Boom Extrapolation Program (MMOC) is computer program for sonic-boom propagation that includes shock coalescence and incorporates effects of asymmetries due to volume and lift. Numerically integrates nonlinear governing equations using data on initial data line approximately one body length from aircraft and yields sonic-boom pressure at ground as function of time or of position at given time. MMOC written in FORTRAN IV.

Darden, C. M.↗

System Predicts Critical Runway Performance Parameters

Runway-navigation-monitor (RNM) and critical-distances-process electronic equipment designed to provide pilot with timely and reliable predictive navigation information relating to takeoff, landing and runway-turnoff operations. Enables pilot to make critical decisions about runway maneuvers with high confidence during emergencies. Utilizes ground-referenced position data only to drive purely navigational monitor system independent of statuses of systems in aircraft.

Millen, Ernest W.↗

Project Magnet High-level Vector Survey Data Reduction

Since 1951, the U.S. Navy, under its Project MAGNET program, has been continuously collecting vector aeromagnetic survey data to support the U.S. Defense Mapping Agency's world magnetic and charting program. During this forty-year period, a variety of survey platforms and instrumentation configurations have been used. The current Project MAGNET survey platform is a Navy Orion RP-3D aircraft which has been specially modified and specially equipped with a redundant suite of navigational positioning, attitude, and magnetic sensors. A review of the survey data collection procedures and calibration and editing techniques applied to the data generated by this suite of instrumentation will be presented. Among the topics covered will be the determination of its parameters from the low-level calibration maneuvers flown over geomagnetic observatories.

Rachel J Coleman↗

Easy-To-Use Connector

Quick-connect/disconnect mechanism consists of two mating assemblies put together easily, even when initially misaligned by fairly large amounts. Used as electrical- or fluid-connection interface. Operated by humans or robots when fast connections must be made without precise positioning, -- for example, on offshore oil rigs, ship-to-dock links, nuclear facilities, and aircraft at loading gates.

Wightman, William D.↗

Advanced Transport Operating System (ATOPS) Flight Management/Flight Controls (FM/FC) software description

The flight software developed for the Flight Management/Flight Controls (FM/FC) MicroVAX computer used on the Transport Systems Research Vehicle for Advanced Transport Operating Systems (ATOPS) research is described. The FM/FC software computes navigation position estimates, guidance commands, and those commands issued to the control surfaces to direct the aircraft in flight. Various modes of flight are provided for, ranging from computer assisted manual modes to fully automatic modes including automatic landing. A high-level system overview as well as a description of each software module comprising the system is provided. Digital systems diagrams are included for each major flight control component and selected flight management functions.

Wolverton, David A.↗

Head-Up Auditory Displays for Traffic Collision Avoidance System Advisories: A Preliminary Investigation

The advantage of a head-up auditory display was evaluated in a preliminary experiment designed to measure and compare the acquisition time for capturing visual targets under two auditory conditions: standard one-earpiece presentation and two-earpiece three-dimensional (3D) audio presentation. Twelve commercial airline crews were tested under full mission simulation conditions at the NASA-Ames Man-Vehicle Systems Research Facility advanced concepts flight simulator. Scenario software generated visual targets corresponding to aircraft that would activate a traffic collision avoidance system (TCAS) aural advisory; the spatial auditory position was linked to the visual position with 3D audio presentation. Results showed that crew members using a 3D auditory display acquired targets approximately 2.2 s faster than did crew members who used one-earpiece head- sets, but there was no significant difference in the number of targets acquired.

Begault, Durand R.↗

Portable Wireless LAN Device and Two-way Radio Threat Assessment for Aircraft Navigation Radios

Measurement processes, data and analysis are provided to address the concern for Wireless Local Area Network devices and two-way radios to cause electromagnetic interference to aircraft navigation radio systems. A radiated emission measurement process is developed and spurious radiated emissions from various devices are characterized using reverberation chambers. Spurious radiated emissions in aircraft radio frequency bands from several wireless network devices are compared with baseline emissions from standard computer laptops and personal digital assistants. In addition, spurious radiated emission data in aircraft radio frequency bands from seven pairs of two-way radios are provided, A description of the measurement process, device modes of operation and the measurement results are reported. Aircraft interference path loss measurements were conducted on four Boeing 747 and Boeing 737 aircraft for several aircraft radio systems. The measurement approach is described and the path loss results are compared with existing data from reference documents, standards, and NASA partnerships. In-band on-channel interference thresholds are compiled from an existing reference document. Using these data, a risk assessment is provided for interference from wireless network devices and two-way radios to aircraft systems, including Localizer, Glideslope, Very High Frequency Omnidirectional Range, Microwave Landing System and Global Positioning System. The report compares the interference risks associated with emissions from wireless network devices and two-way radios against standard laptops and personal digital assistants. Existing receiver interference threshold references are identified as to require more data for better interference risk assessments.

Nguyen, Truong X.↗

Investigation of coaxial jet noise and inlet choking using an F-111A airplane

Measurements of engine noise generated by an F-111A airplane positioned on a thrustmeasuring platform were made at angles of 0 deg to 160 deg from the aircraft heading. Sound power levels, power spectra, and directivity patterns are presented for jet exit velocities between 260 feet per second and 2400 feet per second. The test results indicate that the total acoustic power was proportional to the eighth power of the core jet velocity for core exhaust velocities greater than 300 meters per second (985 feet per second) and that little or no mixing of the core and fan streams occurred. The maximum sideline noise was most accurately predicted by using the average jet velocity for velocities above 300 meters per second (985 feet per second). The acoustic power spectrum was essentially the same for the single jet flow of afterburner operation and the coaxial flow of the nonafterburning condition. By varying the inlet geometry and cowl position, reductions in the sound pressure level of the blade passing frequency on the order of 15 decibels to 25 decibels were observed for inlet Mach numbers of 0.8 to 0.9.

Putnam, T. W.↗

Dynamic Weather Routes: A Weather Avoidance Concept for Trajectory-Based Operations

The integration of convective weather modeling with trajectory automation for conflict detection, trial planning, direct routing, and auto resolution has uncovered a concept that could help controllers, dispatchers, and pilots identify improved weather routes that result in significant savings in flying time and fuel burn. Trajectory automation continuously and automatically monitors aircraft in flight to find those that could potentially benefit from improved weather reroutes. Controllers, dispatchers, and pilots then evaluate reroute options to assess their suitability given current weather and traffic. In today's operations aircraft fly convective weather avoidance routes that were implemented often hours before aircraft approach the weather and automation does not exist to automatically monitor traffic to find improved weather routes that open up due to changing weather conditions. The automation concept runs in real-time and employs two keysteps. First, a direct routing algorithm automatically identifies flights with large dog legs in their routes and therefore potentially large savings in flying time. These are common - and usually necessary - during convective weather operations and analysis of Fort Worth Center traffic shows many aircraft with short cuts that indicate savings on the order of 10 flying minutes. The second and most critical step is to apply trajectory automation with weather modeling to determine what savings could be achieved by modifying the direct route such that it avoids weather and traffic and is acceptable to controllers and flight crews. Initial analysis of Fort Worth Center traffic suggests a savings of roughly 50% of the direct route savings could be achievable.The core concept is to apply trajectory automation with convective weather modeling in real time to identify a reroute that is free of weather and traffic conflicts and indicates enough time and fuel savings to be considered. The concept is interoperable with today's integrated FMS/datalink. Auxiliary(lat/long) waypoints define a minimum delay reroute between current position and a downstream capture fix beyond the weather. These auxiliary waypoints can be uplinked to equipped aircraft and auto-loaded into the FMS. Alternatively, for unequipped aircraft, auxiliary waypoints can be replaced by nearby named fixes, but this could reduce potential savings. The presentation includes an overview of the automation approach and focuses on several cases in terms of potential savings, reroute complexity, best auxiliary waypoint solution vs. named fix solution, and other metrics.

McNally, B. David↗

Survey Summary of AGATE Concepts Demonstration at Annual NATA Convention March 24-26, 1997: Original Survey Data - Volume 2

An AGATE Concepts Demonstration was conducted at the Annual National Air Transportation Association (NATA) Convention in 1997. Following, a 5-minute introductory briefing, an interactive simulation of a single-pilot, single-engine aircraft was conducted. The participant was able to take off, fly a brief enroute segment, fly a Global Positioning System (GPS) approach and landing, and repeat the approach and landing segment. The participant was provided an advanced 'highway-in-the-sky' presentation on both a simulated head-up display and on a large LCD head-down display to follow throughout the flight. A single-lever power control and display concept was also provided for control of the engine throughout the flight. A second head-down, multifunction display in the instrument panel provided a moving map display for navigation purposes and monitoring of the status of the aircraft's systems.

Source record↗

Survey Summary of AGATE Concepts Demonstration at Annual NATA Convention, March 24-26, 1997: Basic Report - Volume 1

An AGATE Concepts Demonstration was conducted at the annual National Air Transportation Association (NATA) Convention in 1997. Following a 5-minute introductory briefing, an interactive simulation of a single-pilot, single-engine aircraft was conducted. The participant was able to take off, fly a brief enroute segment, fly a Global Positioning System (GPS) approach and landing, and repeat the approach and landing segment. The participant was provided an advanced "highway-in-the-sky" presentation on both a simulated head-up display and on a large LCD head-down display to follow throughout the flight. A single-lever power control and display concept was also provided for control of the engine throughout the flight. A second head-down, multifunction display in the instrument panel provided a moving map display for navigation purposes and monitoring of the status of the aircraft's systems. An estimated 100 people observed or participated in the demonstration, and 68 surveys were collected. The pilot ratings of the participants ranged from student to Air Transport Rating with an average of 6089 hours total flight time. The overwhelming response was that technologies that simplify piloting tasks are enthusiastically welcomed by pilots of all experience levels. The increase in situation awareness and use of the head-up display were universally accepted and lauded as steps in the right direction.

Source record↗

Over-the-wing propeller

This invention is an aircraft with a system for increasing the lift drag ratio over a broad range of operating conditions. The system positions the engines and nacelles over the wing in such a position that gains in propeller efficiency is achieved simultaneously with increases in wing lift and a reduction in wing drag. Adverse structural and torsional effects on the wings are avoided by fuselage mounted pylons which attach to the upper portion of the fuselage aft of the wings. Similarly, pylon-wing interference is eliminated by moving the pylons to the fuselage. Further gains are achieved by locating the pylon surface area aft of the aircraft center of gravity, thereby augmenting both directional and longitudinal stability. This augmentation has the further effect of reducing the size, weight and drag of empennage components. The combination of design changes results in improved cruise performance and increased climb performance while reducing fuel consumption and drag and weight penalties.

Johnson, Joseph L., Jr.↗