Research papers

Aero-Propulsive Damping Characterization for eVTOL Aircraft Using Free Motion Wind-Tunnel Testing

This paper describes an electric vertical takeoff and landing (eVTOL) aircraft system identification method applied using three degree-of-freedom (3DOF) free motion wind-tunnel testing.

The Potential of Medical Drones: An Analysis of Current and Future Use Cases

Modern Application of Medical-Based Drone Delivery Drones have been used advantageously by militaries for nearly a century, but their uses in civilian life are still mostly cutting-edge, if not theoretical.

Reducing Landing Site Contamination Using 3-D Trajectory Optimization for Surface Hoppers

Rocket-powered vehicles utilizing Vertical Take-off Vertical Landing (VTVL) are a compelling alternative to surface rovers for exploring planetary and lunar bodies.

Propulsive Trajectory Optimization to Minimize Surface Contamination

Descent retroburns using hydrazine thrusters will generate contaminants in their exhaust that can alter underlying samples, such as water-rich surfaces coinciding with possible life signatures or other science measuremen…

Aircraft icing: Introduction

The objectives of the Workshop were as follows: (1) to assess the current understanding of fixed wing and rotorcraft operational icing environments and problems (2) to evaluate facilities requirements for R&D and certifi…

Aircraft wake turbulence minimization by aerodynamic means

The paper reviews NASA's efforts on wake vortex turbulence minimization by aerodynamic design or retrofit modifications to large transport aircraft.

Bowles-Tatnall Wake Vortex Encounter Hazard Metric

Wake vortex spacing standards constrict the terminal area throughput and impose severe constraints on the overall capacity and efficiency of the National Airspace System.

Impact of Parallel Computing on Large Scale Aeroelastic Computations

Aeroelasticity is computationally one of the most intensive fields in aerospace engineering. Though over the last three decades the computational speed of supercomputers have substantially increased, they are still inade…

Aerodynamic Characterisation of an Experimental Tilt-Wing Aircraft

Computational analysis of experimental aircraft prior to test ights can be a valuable tool to estimate ight characteristics and determine areas of elevated caution.

Analysis of a Hovering Rotor in Icing Conditions

A high fidelity analysis method is proposed to evaluate the ice accumulation and the ensuing rotor performance degradation for a helicopter flying through an icing cloud.

Results of a sub-scale model rotor icing test

A heavily instrumented sub-scale model of a helicopter main rotor was tested in the NASA Lewis Research Center Icing Research Tunnel (IRT) in September and November 1989.

An overview of a model rotor icing test in the NASA Lewis Icing Research Tunnel

During two entries in late 1989, a heavily instrumented sub-scale model of a helicopter main rotor was tested in the NASA LeRC Icing Research Tunnel (IRT).

Incipient torsional stall flutter aerodynamic experiments on a swept three-dimensional wing

The aerodynamics of small amplitude pitching motions near stall have been studied experimentally in order to improve understanding of the torsional stall flutter problem for propeller blades.

Analytic prediction of dynamic stall characteristics.

A new approach is presented for solving the problem of predicting dynamic stall characteristics. In this approach, the unsteady aerodynamic characteristics are related theoretically to static aerodynamic characteristics …

Aircraft wake turbulence avoidance

Aircraft wake turbulence /trailing vortex systems/ avoidance during flight, describing procedures for pilots and tower operators

Turbulence characteristics in the near wake of a compressor rotor blade

This paper is concerned with the turbulence properties in the near wake of a rotating compressor blade. The variation of the axial, tangential and radial intensities as well as stresses across the wake and its decay char…

Evaluation of Fast-Time Wake Vortex Models using Wake Encounter Flight Test Data

This paper describes a methodology for the integration and evaluation of fast-time wake models with flight data. The National Aeronautics and Space Administration conducted detailed flight tests in 1995 and 1997 under th…

Wind Tunnel Testing of Powered Lift, All-Wing STOL Model

Short take-off and landing (STOL) systems can offer significant capabilities to warfighters and, for civil operators thriving on maximizing efficiencies they can improve airspace use while containing noise within airport…

Some Measured Characteristics of Severe Storm Turbulence

Measurements of atmospheric turbulence obtained from airplane flights through severe storms in connection with the National Severe Storms Project will be discussed.

Severe Turbulence and Maneuvering from Airline Flight Records

Digital flight records from reported clear-air turbulence incidents are used to determine winds and turbulence, to determine maneuver g loads, and to analyze control problems.

NASA,FAA,ONERA Swept-Wing Icing and Aerodynamics: Summary of Research and Current Status

NASA, FAA, ONERA, and other partner organizations have embarked on a significant, collaborative research effort to address the technical challenges associated with icing on large scale, three-dimensional swept wings.

Analysis of Low-Speed Stall Aerodynamics of a Swept Wing with Seamless Flaps

Computational fluid dynamics (CFD) analysis was conducted to study the low-speed stall aerodynamics of a Gulfstream G-III airplane (Gulfstream Aerospace Corporation, Savannah, Georgia) swept wing modified with an experim…

Turbulence Climatology at Dallas/Ft.Worth (DFW) Airport: Implications for a Departure Wake Vortex Spacing System

Potential adaptive wake vortex spacing systems may need to rely on wake vortex decay rather than wake vortex transport in reducing wake separations.

DHC-6 Twin Otter Tailplane Airfoil Section Testing in the Ohio State University 7x10 Wind Tunnel

Ice contaminated tailplane stall (ICTS) has been found to be responsible for 16 accidents with 139 fatalities over the last three decades, and is suspected to have played a role in other accidents and incidents.

Lead-Lag Control for Helicopter Vibration and Noise Reduction

As a helicopter transitions from hover to forward flight, the main rotor blades experience an asymmetry in flow field around the azimuth, with the blade section tangential velocities increasing on the advancing side and …

Prediction of stall and post-stall behavior of airfoils at low and high Reynolds numbers

An interactive boundary-layer method, together with the e(super n)-approach to the calculation of transition, has been used to predict the stall and post-stall behavior of airfoils at low and high Reynolds numbers.

Analytical formulation of optimum rotor interdisciplinary design with a three-dimensional wake

An analytical formulation of optimum rotor interdisciplinary design is presented. A finite-state aeroelastic rotor model, coupling generalized dynamic wake with blade finite elements, is applied to perform the optimum ro…

Experimental water droplet impingement data on modern aircraft surfaces

An experimental method has been developed to determine the water droplet impingement characteristics on two- and three-dimensional aircraft surfaces.

Laminar Flow Aircraft Certification

Various topics telative to laminar flow aircraft certification are discussed. Boundary layer stability, flaps for laminar flow airfoils, computational wing design studies, manufacturing requirements, windtunnel tests, an…

Flight test investigation of certification issues pertaining to general-aviation-type aircraft with natural laminar flow

Development of Natural Laminar Flow (NLF) technology for application to general aviation-type aircraft has raised some question as to the adequacy of FAR Part 23 for certification of aircraft with significant NLF.

An experimental investigation of the flap-lag-torsion aeroelastic stability of a small-scale hingeless helicopter rotor in hover

A small scale, 1.92 m diam, torsionally soft, hingeless helicopter rotor was investigated in hover to determine isolated rotor stability characteristics.

Freestream turbulence effects on the development of a rotor wake

The effect of freestream turbulence on the development of a three-dimensional wake of a compressor rotor blade was studied experimentally.

Finite Element Stability Analysis for Coupled Rotor and Support Systems

The effects of fuselage motions on stability and random response were analytically assessed. The feasibility of adequate perturbation models from non-linear trim conditions was studied by computer and hardware experiment…

An unsteady wake model for a hingeless rotor

A simple nonsteady wake model derived from the unsteady moment of the momentum equation for zero advance ratio is correlated with cyclic pitch frequency response tests conducted with a small hingeless rotor model.

Fixed-base simulation study of decoupled controls during approach and landing of a STOL transport airplane

A fixed-base visual simulation study has been conducted to evaluate the use of decoupled controls as a means for reducing pilot workload during approach and landing of an externally blown jet-flap short take-off and land…

Aerodynamic characteristics of vehicle bodies at crosswind conditions in ground proximity

Aerodynamic characteristics of vehicle bodies at crosswind conditions in ground proximity

Prediction of lift and drag for slender sharp-edge delta wings in ground proximity

Predicting lift and drag for slender sharp-edge Delta wings in ground proximity

Effects of ground proximity on the longitudinal aerodynamic characteristics of an unswept aspect-ratio-10 wing

Ground proximity effects of unswept aspect ratio 10 wing on longitudinal aerodynamic characteristics

Relationship Between Magnitude of Applied Spin Recovery Moment and Ensuing Number of Recovery Turns

An analytical study has been made to investigate the relationship between the magnitude of the applied spin recovery moment and the ensuing number of turns made during recovery from a developed spin with a view toward de…

Analysis of deep-stall characteristics of T- tailed aircraft configurations and some recovery procedures.

Deep-stall characteristics of T-tailed aircraft configurations and recovery procedures, noting parameters of pitch-up, angle of attack, etc

A Simulator Study of T-tail Aircraft in Deep Stall Conditions

Fixed base simulation study of T-tail aircraft deep stall and recovery

Scale Model Icing Research Tunnel

NASA Lewis Research Center's Icing Research Tunnel (IRT) is the world's largest refrigerated wind tunnel and one of only three icing wind tunnel facilities in the United States.

A Numerical Simulation Study to Develop an Acceptable Wake Encounter Boundary for a B737-100 Airplane

The National Aeronautics and Space Administration (NASA) is conducting research with the goal of enabling safe improvements in the capacity of the nation's air transportation system.

Vortical flow management for improved configuration aerodynamics: Recent experiences

Recent progress in vortex-control applications for alleviating the adverse consequences of three dimensional separation and vortical interactions on slender body/swept wing configurations is reported.

Wake Vortex Encounter Research

The National Aeronautics and Space Administration (NASA) is conducting research to improve airport capacity by reducing the separation distance between aircraft.

Aerodynamic characteristics in ground proximity

Results from recent investigations in the Langley V/STOL tunnel of an externally blown flap and an upper surface blown flap configuration in ground proximity are presented.

Effects of thrust reversing in ground proximity

The changes in stability and control characteristics encountered by a thrust reversing aircraft during its final approach, landing, and ground roll are described.

Effects of ground proximity on a low aspect ratio propulsive wing/canard configuration

The effect of near proximity to the ground are investigated on a low aspect ratio propulsive wing/canard concept at STOL conditions. Data were obtained on a wing/body and wing/body/canard configuration at various heights…

Safety hazard of aircraft icing

The problem of aircraft icing is reported as well as the type of aircraft affected, the pilots involved, and an identification of the areas where reduction in icing accidents are readily accomplished.

Deep-Stall Aerodynamic Characteristics of T-Tail Aircraft

A wind-tunnel research program has been under-taken by the NASA to study the aerodynamic characteristics of T-tail aircraft at high angles of attack.