Engineering topics

Stough, H. Paul, III

Publications and source records attributed to Stough, H. Paul, III.

13 records

NASA NTRS2010

Characterizing a Wake-Free Safe Zone for the Simplified Aircraft-Based Paired Approach Concept

The Federal Aviation Administration (FAA) has proposed a concept of operations geared towards achieving increased arrival throughput at U.S. Airports, known as the Simplified Aircraft-based Paired Approach (SAPA) concept. In this study, a preliminary characterization of a wake-free safe zone (WFSZ) for the SAPA concept has been performed. The experiment employed Monte-Carlo simulations of varying approach profiles by aircraft pairs to closely-spaced parallel runways. Three different runway lateral spacings were investigated (750 ft, 1000 ft and 1400 ft), along with no stagger and 1500 ft stagger between runway thresholds. The paired aircraft were flown in a leader/trailer configuration with potential wake encounters detected using a wake detection surface translating with the trailing aircraft. The WFSZ is characterized in terms of the smallest observed initial in-trail distance leading to a wake encounter anywhere along the approach path of the aircraft. The results suggest that the WFSZ can be characterized in terms of two primary altitude regions, in ground-effect (IGE) and out of ground-effect (OGE), with the IGE region being the limiting case with a significantly smaller WFSZ. Runway stagger was observed to only modestly reduce the WFSZ size, predominantly in the OGE region.

Guerreiro, Nelson M.↗

NASA NTRS2007

Aircraft Weather Mitigation for the Next Generation Air Transportation System

Atmospheric effects on aviation are described by Mahapatra (1999) as including (1) atmospheric phenomena involving air motion - wind shear and turbulence; (2) hydrometeorological phenomena - rain, snow and hail; (3) aircraft icing; (4) low visibility; and (5) atmospheric electrical phenomena. Aircraft Weather Mitigation includes aircraft systems (e.g. airframe, propulsion, avionics, controls) that can be enacted (by a pilot, automation or hybrid systems) to suppress and/or prepare for the effects of encountered or unavoidable weather or to facilitate a crew operational decision-making process relative to weather. Aircraft weather mitigation can be thought of as a continuum (Figure 1) with the need to avoid all adverse weather at one extreme and the ability to safely operate in all weather conditions at the other extreme. Realistic aircraft capabilities fall somewhere between these two extremes. The capabilities of small general aviation aircraft would be expected to fall closer to the "Avoid All Adverse Weather" point, and the capabilities of large commercial jet transports would fall closer to the "Operate in All Weather Conditions" point. The ability to safely operate in adverse weather conditions is dependent upon the pilot s capabilities (training, total experience and recent experience), the airspace in which the operation is taking place (terrain, navigational aids, traffic separation), the capabilities of the airport (approach guidance, runway and taxiway lighting, availability of air traffic control), as well as the capabilities of the airplane. The level of mitigation may vary depending upon the type of adverse weather. For example, a small general aviation airplane may be equipped to operate "in the clouds" without outside visual references, but not be equipped to prevent airframe ice that could be accreted in those clouds.

Stough, H. Paul, III↗

NASA NTRS2006

New Technologies for Reducing Aviation Weather-Related Accidents

The National Aeronautics and Space Administration (NASA) has developed technologies to reduce aviation weather-related accidents. New technologies are presented for data-link and display of weather information to aircraft in flight, for detection of turbulence ahead of aircraft in flight, and for automated insitu reporting of atmospheric conditions from aircraft.

Stough, H. Paul, III↗

NASA NTRS2005

New Technologies for Weather Accident Prevention

Weather is a causal factor in thirty percent of all aviation accidents. Many of these accidents are due to a lack of weather situation awareness by pilots in flight. Improving the strategic and tactical weather information available and its presentation to pilots in flight can enhance weather situation awareness and enable avoidance of adverse conditions. This paper presents technologies for airborne detection, dissemination and display of weather information developed by the National Aeronautics and Space Administration (NASA) in partnership with the Federal Aviation Administration (FAA), National Oceanic and Atmospheric Administration (NOAA), industry and the research community. These technologies, currently in the initial stages of implementation by industry, will provide more precise and timely knowledge of the weather and enable pilots in flight to make decisions that result in safer and more efficient operations.

Stough, H. Paul, III↗

NASA NTRS2001

The Effect of Ownship Information and NexRad Resolution on Pilot Decision Making in the Use of a Cockpit Weather Information Display

A two-phase experiment was conducted to explore the effects of data-link weather displays upon pilot decision performance. The experiment was conducted with 49 instrument rated pilots who were divided into four groups and placed in a simulator with a realistic flight scenario involving weather containing convective activity. The inflight weather display depicted NEXRAD images, with graphical and textual METARs over a moving map display. The experiment explored the effect of weather information, ownship position symbology and NEXRAD cell size resolution. The phase-two experiment compared two groups using the data-linked weather display with ownship position symbology. These groups were compared to the phase-one group that did not have ownship position symbology. The phase-two pilots were presented with either large NEXRAD cell size (8 km) or small cell size (4 km). Observations noted that the introduction of ownship symbology did not appear to significantly impact the decision making process, however, the introduction of ownship did reduce workload. Additionally, NEXRAD cell size resolution did appear to influence the tactical decision making process.

Novacek, Paul F.↗

NASA NTRS2000

Reducing Aviation Weather-Related Accidents Through High-Fidelity Weather Information Distribution and Presentation

In February 1997, the US President announced a national goal to reduce the fatal accident rate for aviation by 80% within ten years. The National Aeronautics and Space Administration established the Aviation Safety Program to develop technologies needed to meet this aggressive goal. Because weather has been identified (is a causal factor in approximately 30% of all aviation accidents, a project was established for the development of technologies that will provide accurate, time and intuitive information to pilots, dispatchers, and air traffic controllers to enable the detection and avoidance of atmospheric hazards. This project addresses the weather information needs of general, corporate, regional, and transport aircraft operators. An overview and status of research and development efforts for high-fidelity weather information distribution and presentation is discussed with emphasis on weather information in the cockpit.

Stough, H. Paul, III↗

NASA NTRS1992

Stall-Departure-Resistance Enhancer

Stall-departure-resistance enhancer imposes lesser drag penalty than nortex generators of older types. Increases lift by as much as 30 percent at angles of attack otherwise in poststall region. Device is flat plate wedge with 60 degree sweep angle and attached so it protrudes from leading edge of wing. Tip is sharp point, and edges made thin and sharp to induce good vortical flow. Applications include those intended to increase safety for broad range of aircraft, including trainers, fighters, general-aviation aircraft, and commercial transport aircraft. Nonaerospace applications where flow stall is problem under certain conditions, such as in control of separation in flow diffusers. Other applications in fluid machinery and fluid flow.

Ross, Holly M.↗

NASA NTRS1990

A summary of spin-recovery parachute experience on light airplanes

From 1977 to 1989, the NASA Langley Research Center conducted stall/spin flight tests of variations of four typical light airplanes. Each was equipped with an identical tail-mounted, spin-recovery parachute system. The system was used 29 times to arrest otherwise unrecoverable spins and was used at least twice on each airplane. The 10.5 ft diameter, ring-slot, spin-recovery parachute with 20 ft attachment lines and drag coefficient of .545 provided recovery from spins at angles of attack of 32 to 79 degrees and rotation rates of 122 to 261 degrees per second in less than 3 1/2 turns.

Stough, H. Paul, III↗

NASA NTRS1987

NASA small civil airplane research

NASA-Langley's ongoing research programs on behalf of performance, safety, and utility enhancements for small civil aircraft have over the last decade introduced important advancements in natural laminar flow inducement and stall/spin recovery and prevention. The achievability and maintainability of natural laminar flow has led to performance improvements of as much as 25 percent. Recent research has improved predictive techniques for aircraft stall/spin characteristics, and also led to the development of a wing leading edge design for enhanced spin resistance.

Stough, H. Paul, III↗

NASA NTRS1987

Flight investigation of the effects of an outboard wing-leading-edge modification on stall/spin characteristics of a low-wing, single-engine, T-tail light airplane

Flight tests were performed to investigate the change in stall/spin characteristics due to the addition of an outboard wing-leading-edge modification to a four-place, low-wing, single-engine, T-tail, general aviation research airplane. Stalls and attempted spins were performed for various weights, center of gravity positions, power settings, flap deflections, and landing-gear positions. Both stall behavior and wind resistance were improved compared with the baseline airplane. The latter would readily spin for all combinations of power settings, flap deflections, and aileron inputs, but the modified airplane did not spin at idle power or with flaps extended. With maximum power and flaps retracted, the modified airplane did enter spins with abused loadings or for certain combinations of maneuver and control input. The modified airplane tended to spin at a higher angle of attack than the baseline airplane.

Stough, H. Paul, III↗

NASA NTRS1987

Spin resistance evaluation of a light airplane

A brief history of stall/spin technology for light general aviation airplanes and proposed criteria to describe desirable characteristics of a spin-resistant airplane are presented. Flight tests of a representative light airplane to evaluate compliance with and usefulness of the criteria are presented. The baseline airplane configuration would not meet the spin resistance criteria. Tests of the airplane with a wing leading edge modification to enhance its spin resistance showed compliance with the proposed criteria.

Stough, H. Paul, III↗

NASA NTRS1987

Flight investigation of the effect of tail configuration on stall, spin, and recovery characteristics of a low-wing general aviation research airplane

Flight tests were performed to investigate the stall, spin, and recovery characteristics of a low-wing, single-engine, light airplane with four interchangeable tail configurations. The four tail configurations were evaluated for effects of varying mass distribution, center-of-gravity position, and control inputs. The airplane tended to roll-off at the stall. Variations in tail configuration produced spins ranging from 40 deg to 60 deg angle of attack and turn rates of about 145 to 208 deg/sec. Some unrecoverable flat spins were encountered which required use of the airplane spin chute for recovery. For recoverable spins, antispin rudder followed by forward wheel with ailerons centered provided the quickest spin recovery. The moderate spin modes agreed very well with those predicted from spin-tunnel model tests, however, the flat spin was at a lower angle of attack and a slower rotation rate than indicated by the model tests.

Stough, H. Paul, III↗

NASA NTRS1987

Evaluation of airplane spin resistance using proposed criteria for light general aviation airplanes

Proposed criteria to describe desirable characteristics of a spin-resistant airplane are reviewed. Flight tests of two representative light airplanes to evaluate compliance with the criteria are also presented. The baseline airplane configurations would not meet the spin resistance criteria. Tests of the airplanes with a wing leading edge modification to enhance spin resistance showed compliance with the proposed criteria. The tests demonstrated the usefulness of the criteria when the criteria are applied in the manner described.

Stough, H. Paul, III↗