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Technical Paper

World's First VTOL Airplane Convair/Navy XFY-1 Pogo

The Convair/Navy XFY-1 VTOL fighter was ahead of its time. In the early 1950s it became the first airplane to take off vertically, hover, transition to high speed level flight, transition back to hover, and land vertically. Pilot “Skeets” Coleman made a number of successful flights at Moffett Field South of San Francisco, at Brown Field near the California/Mexican border, and at San Diego's Lindbergh Field. This “first of a kind” aircraft soon adopted the name “POGO”. The POGO with its stall proof delta wing had near perfect aerodynamic characteristics in hover, transition and level flight. There were no “black boxes” needed for stability augmentation. The POGO was one of the very first aircraft to use hydraulic power flight controls - a system used today on all modern fighter and transport aircraft.
Technical Paper

Work-Energy Relationships for the Collinear Single Degree of Freedom Impact Model under the Case of Net Unbalanced Externally Applied Forces

Externally applied unbalanced forces and their corresponding impulses are generally excluded from consideration in regards to the evaluation of the collision phase events for a system comprised of two motor vehicles undergoing collinear impact. This exclusion is generally warranted secondary to the fact that the collision force and its corresponding impulse are dominant during the collision phase. Conceptually, two exclusions exist to this approach. The first is the situation in which significant physical restraints are present to the displacement of one or both collision partners and are of sufficient magnitude as to require inclusion. Generally, this represents the exceptional case and includes, but is not limited to, situations in which one vehicle is snagged, in a non-eccentric manner, by a rigid narrow-width object such as a pole or other similar restraint, prior to the occurrence of the subsequent vehicle-to-vehicle collision under evaluation.
Technical Paper

Wireless Communication-The Link Between the Rolling Lan and the Rest of the World

Over the past years many have been predicting various dramatic changes in the vehicle including automatic route guidance, the office in the vehicle, and the auto PC. There are a number of factors which need to come together before significant momentum can develop toward realizing any of these predictions. This paper enumerates these factors and explores the current state and possible evolution of each. While each of these factors could stall progress, the linchpin is likely to be wireless communication. The current state of wireless and its capabilities going forward are examined in depth.
Technical Paper

Wing Modification for Increased Spin Resistance

A simple wing leading-edge modification has been developed that delays outer wing panel stall, thus maintaining roll damping to higher angles of attack and delaying the onset of autorotation. The stall angle of attack of the outer wing panel has been shown to be a function of the spanwise length of the leading-edge modification. The margin of spin resistance provided by the modification is being explored through flight tests. Preliminary results have been used to evaluate spin resistance in terms of the difference in angle of attack between outer wing panel stall and the maxiumum attainable angle of attack.
Technical Paper

Windshield Wiper Linkage Analysis

The Kinematic Analysis Methods Computer Program that has been used by Ford Motor Co. to evaluate mechanisms for the past four years has been modified to generate performance curves for windshield wiper linkages directly using a Calcomp Plotter. Problems such as stalling, “jerky” operation, and excessive phase lag between wipers can be detected early in the design stages by careful evaluation of the curves.
Technical Paper

Wind-Tunnel and On-Road Wind Noise: Comparison and Replication

A KIA Soul was instrumented to measure the relative velocity (magnitude and yaw angle) at the front of the vehicle and in-cabin sound at a location close to the side glass near the A-pillar vortex impingement. Tests were conducted at a proving ground under a range of conditions from low wind conditions (~3 m/s) to moderate (7-8 m/s) wind speeds. For any given set of atmospheric conditions the velocity and sound data at any given position on the proving ground were noted to be very repeatable, indicating that the local wakes dominated the "turbulent" velocity field. Testing was also conducted in an aeroacoustic wind tunnel in smooth flow and with a number of novel turbulence generating methods. The resulting sounds were analyzed to study the modulation at frequencies likely to result in fluctuation strength type noise.
Technical Paper

Wind-Tunnel Tests of Vehicle Cooling System Performance at High Blockage

Wind tunnels provide a convenient, repeatable method of assessing vehicle engine cooling, yet important draw-backs are the lack of a moving ground and rotating wheels, blockage constraints and, in some tunnels, the inability to simulate ambient temperatures. A series of on-road and wind-tunnel experiments has been conducted to validate a process for evaluating vehicle cooling system performance in a high blockage aerodynamic wind tunnel with a fixed ground simulation. Airflow through the vehicle front air intake was measured via a series of pressure taps and the wind-tunnel velocity was adjusted to match the corresponding pressures found during the road tests. In order to cope with the inability to simulate ambient temperatures, the technique of Specific Dissipation (SD) was used (which has previously been shown to overcome this problem).
Technical Paper

Wind-Tunnel Modelling off Commercial Vehicle Drag-Reducing Devices: Three Case Studies

Road and wind-tunnel tests are presented which examine the drag coefficient reductions from aerodynamic devices fitted to three trucks. A modified SAE Type II procedure utilising an instrumented chase car, evaluated on-road, constant-speed drag reductions as a function of yaw angle. At 100 km/h, turbulence intensities of 1% - 4% were measured. The wind-tunnel results generally overestimated drag savings, particularly at high yaw angles. This was greater for cabin deflectors than for solid fairings. Simulating higher turbulence intensities gave improved agreement and it is argued that turbulence is a dominant modelling parameter.
Technical Paper

Wind-Tunnel Measurements of Wing-Canard Interference and a Comparison with Various Theories

CANARD-CONFIGURED AIRCRAFT DESIGNS have played a historic role in aeronautical research. However, only in the past decade or two has a canard been incorporated into a significant number of aircraft designs. Powered flight began with the Wright Flyer, which was a canard-configured aircraft. Unfortunately, however, that aircraft was longitudinally unstable and the misconception arose that all canard aircraft would be unstable in pitch, irrespective of the placement of the center of gravity. In the early years of aircraft development, the canard concept was dropped in favor of conventional tailaft designs. It was not until the 1960s that canards were again seriously considered for several high-speed, designs. For example, in the United States’ supersonic transport program, a canard was initially considered; because of several problems with aerodynamic interference, however, the idea was abandoned.
Technical Paper

Wind-Tunnel Investigation of the Low-Speed Aerodynamics of Slender Accelerator-Type Configurations

An investigation was conducted in the Langley 14- by 22-Foot Subsonic Tunnel to determine the low-speed aerodynamic characteristics of a generic, hypersonic accelerator-type configuration. The model consisted of a delta wing configuration incorporating a conical forebody, a simulated wrap-around engine package, and a truncated conical aftbody. Six-component force and moment data were obtained over a range of angle of attack from -4° to 30° and for a sideslip range of ±20°. In addition to tests of the basic configuration, component build-up tests were conducted; and the effects of power, forebody nose geometry, a canard surface, fuselage strakes, and lower surface engines alone were also determined. Control power was investigated via the testing of wing flap deflections as well as the deflections of an aftbody flap in the exhaust flow. Surface pressure data were obtained at several longitudinal locations along the conical forebody.
Technical Paper

Wind Tunnel Testing of an Advanced Flying Automobile Concept

A 1:12 scale model based on the Sokol A350 Advanced Flying Automobile Concept was examined in the San Diego State University Low Speed Wind Tunnel for performance and stability characteristics. Observation showed that the model stalled at angles of attack above 12 degrees, corresponding to a maximum coefficient of lift of 1.54 and a drag coefficient of .284 for the wing center position. Analysis of the moments revealed that the test model was unstable with the current design specifications, however varying the wing location provided additional insight on the stability of the model. With design changes based on moving the center of gravity forward, the prototype vehicle is capable of creating enough lift to fly safely.
Technical Paper

Wind Tunnel Test of Cab Extender Incidence on Heavy Truck Aerodynamics

A wind tunnel experiment has been conducted to determine the changes in drag and side force due to the presence and position of cab extenders on a model of a commercial tractor-trailer truck. The geometric variables investigated are the cab extenders angle of incidence, the tractor-trailer spacing and the yaw angle of the vehicle. Three cab extender angles were tested-0°, 15° (out) and -15° (in) with respect to the side of the tractor. The cab and trailer models have the same width and height. The minimum drag coefficient was found for the tractor and trailer combination when the cab extenders were set to 0° angle of incidence with respect to the headwind. This result holds for all yaw angles with moderate gap spacing between the tractor and trailer. This study suggests that commercial tractor-trailer trucks can benefit from adjustable cab extender settings; 0° when using a trailer and -15° when no trailer is used.
Technical Paper

Wind Tunnel Investigations of a High Speed Stowed Rotor Aircraft

Model rotor tests were conducted to investigate aeroelastic and aerodynamic behavior of a stowed rotor aircraft during stopping and stowing of the rotor. Results at various tunnel speeds, using rotors of varying stiffness, indicated the lower limits of blade stiffness necessary to provide adequate airframe clearance and manageable hub moments during conversion. The effects of blade pitch control during conversion were evaluated, and the control values required to minimize stress and moments were established. Various rotor stopping positions were examined and improved aircraft stability and drag were shown to result from initiating blade fold with one blade stopped over the nose. An oscillatory response phenomenon encountered during blade fold was thoroughly explored, and means to prevent the oscillation were successfully tested. The tests gave further evidence that the stowed rotor concept is feasible, but showed that stiff blades may be required for successful conversion in rough air.
Technical Paper

Wind Tunnel Investigation of an Improved Upper Surface Blown-Flap Transport Semi-Span Model

The ASUKA was based upon the airframe of the home produced C-1 tactical transport which was modified into an Upper Surface Blowing (USB) powered high lift STOL aircraft. But the wing configuration was not changed. Therefore, this Experimental Aircraft doesn't always have the optimum configuration of a USB type aircraft. This paper describes the investigations which have been conducted to improve the aerodynamic characteristics of a subsonic jet transport semi-span model with an Upper Surface Blowing Flap system which has been newly designed using the NAL STOL-CAD program. The tests were conducted in the NAL 2- by 2-meter Gust Wind Tunnel and results were obtained for several flap and slat deflections at engine thrust coefficients from 0 to 1.85. As compared with the aerodynamic characteristics of the ASUKA model, we obtained the possibility of reduction of the airframe weight and significant improvement of the aerodynamic characteristics.
Technical Paper

Wind Tunnel Balance

This paper relates to the wind tunnel balance design that aims to meet the need for reliable but more affordable equipment that could accurately perform Aerodynamic measurements and act on three axes, being a Multitasking device, adaptable for prototypes of aircrafts, automobiles, buildings, sports products design, etc., through digital control that will measure the drag, lift and the aerodynamic pitch moment. The main task is stimulating creativity, to solve real problems and reduce technology dependence. The composite tubes used in the fixation of the "Sting-Compound" were chosen to avoid inaccurate measurements and have high flexural strength, even with a small cross section. That's feature is justified because the terminal velocity of wind tunnel is 50 m/s (97 knots), enabling to search many different model sizes and subsonic Reynolds speed regime.
Technical Paper

Wind Noise and Drag Optimization Test Method for Sail-Mounted Exterior Mirrors

An L18 Taguchi-style Design of Experiments (DOE) with eight factors was used to optimize exterior mirrors for wind noise and drag. Eighteen mirror properties were constructed and tested on a full size greenhouse buck at the Lockheed low-speed wind tunnel in Marietta, GA. Buck interior sound data and drag measurements were taken at 80 MPH wind speed (0° yaw angle). Key wind noise parameters were the fore/aft length of mirror housing and the plan view angle of the mirror housing's inboard surface. Key drag parameters were the fore/aft length of the mirror housing, the cross-section shape of the mirror pedestal, and the angle of the pedestal (relative to the wind).
Journal Article

Wind Noise Measurements for Automotive Mirrors

In order to understand the flow and wind noise characteristics generated by the outside rearview (OSRV) mirror, a series of wind noise measurements for two production mirrors was conducted at the GM Aerodynamics Lab (GMAL) wind tunnel. These measurements included the time-averaged static pressures, surface noise sources, and far field propagation noise. The data obtained in this investigation will be used for future CFD numerical validations. The two mirrors chosen for the test are the GMT360 (a truck mirror) and the GMX320 (a sedan mirror). The test mirror was mounted on an elevated table which was specially designed for the current project to avoid any significant flow boundary layer buildup on the wind tunnel floor. The test conditions reported in this paper include four inlet speeds of 30, 50, 70 and 90 mph at 0 yaw angle. To record the wind noise sources, nine surface flush-mount microphones were used.
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Wiley SAE MOBILUS® eBook Package

Committed to being the primary source for aerospace and ground vehicle engineering resources, SAE International has added the full compilation of our Wiley eBook collections to the SAE MOBILUS® technical resource platform. Purchasable as an annual subscription and containing the titles from the Wiley Aerospace Collection, the Wiley Automotive Collection, the Wiley Computer Systems Collection, and the Wiley Cyber Security Collection.
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Wiley Automotive Collection

Purchasable as an annual subscription, the Wiley Automotive Collection contains 20 eBook titles and focuses on a wide range of categories, including engines, transmission, chassis, body, electrical, safety, and manufacturing. Titles covering new and emerging topics such as battery technology and electric and hybrid vehicles are included as well, making the series an essential addition to any institution’s automotive resources.
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Wiley Aerospace Collection

Purchasable as an annual subscription and containing 30 eBook titles, the Wiley Aerospace Collection covers valuable engineering subject matter, such as aircraft fuel systems, aerodynamics, and propulsion. The series also goes beyond engineering, including eBooks on planning, logistical issues, and how human behavior can be managed and controlled while operating aircraft.