Search NASA⌕ Search

SEARCH · Search NASA

Results for “VTOL”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Performance and Flowfield Measurements on a 10-inch Ducted Rotor VTOL UAV

A ducted fan VTOL UAV with a 10-inch diameter rotor was tested in the US Army 7-by 10-Foot Wind Tunnel. The test conditions covered a range of angle of attack from 0 to 110 degrees to the freestream. The tunnel velocity was varied from 0 (simulating a hover condition) to 128 ft/sec in propeller mode. A six-component internal balance measured the aerodynamic loads for a range of model configurations. including the isolated rotor, the isolated duct, and the full configuration of the duct and rotor. For some conditions, hotwire velocity surveys were conducted along the inner and outer surface of the duct and across the downstream wake. In addition, fluorescent oil flow visualization allowed the flow separation patterns inside and outside of the duct to be mapped for a few test conditions. Two different duct shapes were tested to determine the performance effects of leading edge radius. For each duct, a range of rotor tip gap from 1%R to 4.5%R was tested to determine the performance penalty in hover and axial flight. Measured results are presented in terms of hover performance, hover performance in a crosswind, and high angle of attack performance in propeller mode. In each case, the effects of both tip gap and duct leading edge radius are illustrated using measurements. Some of the hover performance issues were also studied using a simple analytical method, and the results agreed with the measurements.

Martin, Preston↗
NASA NTRS2006

Design of a Long Endurance Titan VTOL Vehicle

Saturn s moon Titan promises insight into many key scientific questions, many of which can be investigated only by in situ exploration of the surface and atmosphere of the moon. This research presents a vertical takeoff and landing (VTOL) vehicle designed to conduct a scientific investigation of Titan s atmosphere, clouds, haze, surface, and any possible oceans. In this investigation, multiple options for vertical takeoff and horizontal mobility were considered. A helicopter was baselined because of its many advantages over other types of vehicles, namely access to hazardous terrain and the ability to perform low speed aerial surveys. Using a nuclear power source and the atmosphere of Titan, a turbo expander cycle produces the 1.9 kW required by the vehicle for flight and operations, allowing it to sustain a long range, long duration mission that could traverse the majority of Titan. Such a power source could increase the lifespan and quality of science for planetary aerial flight to an extent that the limiting factor for the mission life is not available power but the life of the mechanical parts. Therefore, the mission could potentially last for years. This design is the first to investigate the implications of this potentially revolutionary technology on a Titan aerial vehicle.

Prakash, Ravi↗
NASA NTRS2010

NASA Puffin Electric Tailsitter VTOL Concept

Electric propulsion offers dramatic new vehicle mission capabilities, not possible with turbine or reciprocating engines; including high reliability and efficiency, low engine weight and maintenance, low cooling drag and volume required, very low noise and vibration, and zero emissions. The only penalizing characteristic of electric propulsion is the current energy storage technology level, which is set to triple over the next 5-10 years through huge new investments in this field. Most importantly, electric propulsion offers incredible new degrees of freedom in aircraft system integration to achieve unprecedented levels of aerodynamic, propulsive, control, and structural synergistic coupling. A unique characteristic of electric propulsion is that the technology is nearly scale-free, permitting small motors to be parallelized for fail-safe redundancy, or distributed across the airframe for tightly coupled interdisciplinary functionality without significant impacts in motor-controller efficiency or specific weight. Maximizing the potential benefit of electric propulsion is dependent on applying this technology to synergistic mission concepts. The vehicle missions with the most benefit include those which constrain environmental impact (or limit noise, exhaust, or emission signatures) are short range, or where large differences exist in the propulsion system sizing between takeoff and cruise conditions. Electric propulsion offers the following unique capabilities that other propulsion systems can t provide for short range Vertical Takeoff and Landing (VTOL) aircraft; elimination of engine noise and emissions, drastic reduction in engine cooling and radiated heat, drastic reduction in vehicle vibration levels, drastic improvement in reliability and operating costs, variable speed output at full power, for improved cruise efficiency at low tip-speed, elimination of high/hot sizing penalty, and reduction of engine-out penalties.

Moore, Mark D.↗
NASA NTRS2015

Experiment Design for Complex VTOL Aircraft with Distributed Propulsion and Tilt Wing

Selected experimental results from a wind tunnel study of a subscale VTOL concept with distributed propulsion and tilt lifting surfaces are presented. The vehicle complexity and automated test facility were ideal for use with a randomized designed experiment. Design of Experiments and Response Surface Methods were invoked to produce run efficient, statistically rigorous regression models with minimized prediction error. Static tests were conducted at the NASA Langley 12-Foot Low-Speed Tunnel to model all six aerodynamic coefficients over a large flight envelope. This work supports investigations at NASA Langley in developing advanced configurations, simulations, and advanced control systems.

Murphy, Patrick C.↗
NASA NTRS2018

Observations from Exploration of VTOL Urban Air Mobility Designs

NASA is exploring rotorcraft designs for VTOL air taxi operations, also known as urban air mobility (UAM) or on-demand mobility (ODM) applications. Several concept vehicles have been developed, intended to focus and guide NASA research activities in support of aircraft development for this emerging market. This paper summarizes the work conducted to date. To initially explore the broad design trade-space, three concept vehicles were designed: a quadrotor with electric propulsion; a side-by-side helicopter with hybrid propulsion; and a tiltwing with turbo-electric propulsion. Next a specific UAM mission was developed, accounting for the existing geography, population patterns, infrastructure, and weather in twenty-eight markets across the United States of America. Then in order to quantify the tradeoffs and performance targets necessary for practical implementation of the UAM vision, aircraft were designed to perform this mission, considering a range of aircraft types and propulsion system architectures: quadrotor aircraft, with turboshaft and all-electric propulsion; side-by-side aircraft, with turboshaft and all-electric propulsion; and lift+cruise aircraft with all-electric and turbo-electric propulsion. In examining these vehicles, performance targets and recurring technology themes emerged, which can guide investments in research and development within NASA, other government agencies, academia, and industry. In addition, results from the designs support observations about the trade-offs and key design decisions.

Observations from Exploration↗
NASA NTRS2019

Evaluation of Impact Energy Attenuators and Composite Material Designs of a UAM VTOL Concept Vehicle

The development of Vertical Take-off and Landing (VTOL) vehicles for the Urban Air Mobility (UAM) markets presents a need for light weight vehicle structures with effective occupant protection capabilities. The National Aeronautics and Space Administration (NASA) has been working to fill that need, recently developing a cadre of concept vehicles to help characterize UAM design feasibility. This paper describes a study, using these concept vehicles, to evaluate the use of advanced composite structure and energy attenuating designs in the UAM vehicle design space. A finite element model (FEM) of a single passenger quadrotor concept vehicle was developed in LS-Dyna® and simulated under nominal and off-nominal vertical impact conditions. A variety of energy attenuating design mechanisms were implemented within this model to quantify their effectiveness in improving occupant safety. The use of carbon composites in both the energy attenuation mechanisms and vehicle structure was evaluated. The results of this study found significant reduction in occupant injury risk with the implementation of energy absorbing composite crush tubes and landing gear within the vehicle design. Additionally the use of a carbon fiber as a structural material was found to provide significant weight reduction while maintaining similar occupant loads to that predicted with an aluminum structure. This work provides a preliminary evaluation of design mechanisms and materials that may be used to optimize occupant protection capabilities within the UAM market.

Putnam, Jacob↗
NASA NTRS2018

Aviation Global Demand Forecast Model Development and ISAAC Studies: UAS - VTOL Cargo Study

This report examines the potential market of cargo ODM operations in the Northern California area. The analysis presented describes how UAS VTOL cargo aircraft (called heron Cargo ODM) could be used in a dual-role purpose to carry cargo and passengers in a large metropolitan area. The purpose of this study is to provide NASA with insights on the potential market for cargo ODM operations.The analysis presented in the report uses various datasets including the American Community Survey (ACS), LODES data and the IHS International Transearc hdatabase.

Mihir Rimjha↗
NASA NTRSDate not supplied

Wind Tunnel Testing Techniques for a Tandem Tilt-Wing, Distributed Electric Propulsion VTOL Aircraft

Urban Air Mobility (UAM) vertical takeoff and landing (VTOL) aircraftdesigns frequently include multiple distributed propulsors, complex wing-propulsor aerodynamics, significant airframe configuration changes during normal flight operations, and no historical database regarding the best ways to transition between vertical and horizontal flight. This paper describes the methodology used for wind tunnel testing of the Langley Aerodrome No. 8 (LA-8) in the NASA Langley 12-Foot Low-SpeedTunnel during multiple test entries in 2019 and2020. The LA-8 is a tandem tilt-wing aircraft with 4 motor-propellerunits and 4 control surfaces distributed across each wing, plus an inverted V-tail with 2 ruddervators on the fuselage. An initial tunnel entryused one-factor-at-a-time (OFAT) testing to (1) define candidate trimmed transition corridors between vertical and horizontal flight, (2) assess whether there was adequate control authority, and (3) define appropriatetest factor ranges for subsequent design of experiment (DOE) wind tunnel testing. The total number of independent variables for these wind tunnel tests (23) made DOE testing an efficient option for assessing the large number of potential interactions associated with the LA-8. The general advantages and disadvantages of OFAT and DOE wind tunnel testing techniques are also discussed –along with the benefits of a combined approach

wind tunnel research techniques↗
NASA NTRSDate not supplied

Computational Aerodynamics Study of the Lift+Cruise VTOL Concept Vehicle Components

This paper describes a building-block approach for high-fidelity computational fluid dynamic simulations of NASA’s Lift+Cruise (L+C) Vertical Take-off and Landing (VTOL) concept vehicle. The Reynolds-Averaged Navier-Stokes (RANS) equations are solved on overset structured grids using OVERFLOW. For these analyses, overset meshes are generated using recently developed automated meshing tools. A baseline study is initially performed on the vehicle fuselage with wings and tails. Vehicle components such as pylons and gears are then added individually and together to study incremental component aerodynamic effects. The results from this study are also used to demonstrate the capabilities of the automatic meshing tools for performing rapid computational analyses.

RVLT↗
NASA NTRS2018

VTOL Urban Air Mobility Concept Vehicles for Technology Development

The current push for Urban Air Mobility (UAM) is predicated on the feasibility of novel aircraft types, which will be enabled by the near-term availability of mature technology for high performance subsystems. A number of candidate concept aircraft are presently being designed to meet a set of UAM requirements, in order to quantify the tradeoffs and performance targets necessary for practical implementation of the UAM vision. In examining these vehicles, performance targets and recurring technology themes emerge, which may guide investments in research and development within NASA, other government agencies, academia, and industry.

Urban Air Mobility↗
NASA NTRS2018

Observations from Exploration of VTOL Urban Air Mobility Designs

This presentation will be displayed on the Aeromechanics Branch website. It outlines: NASA Exploration of Urban Air Mobility, Reduced-Emission Rotorcraft Concepts, Concept Vehicles for Air Taxi Operations, Vehicles for UAM Mission and Market and Observations.

Urban Air Mobility Designs↗
NASA NTRSDate not supplied

A Robust Uniform Control Approach for VTOL Aircraft

We present a uniform control approach for transitioning vertical take-off and landing aircraft. The approach combines several well-understood linear techniques, including robust servomechanism linear quadratic regulation, control allocation, and gain scheduling, to provide a practical control framework that can be used to unify the control design process in all flight regimes. The choice of command variables provides a pilot/operator with a uniform set of intuitive control inputs through all phases of flight while also being easily integrated into autonomous trajectory tracking operations. The control method is applied to the NASA LA-8 aircraft, a tandem tiltwing distributed electric propulsion research vehicle designed at NASA Langley Research Center. The trim envelope of the aircraft is explored and the aircraft control authority analyzed throughout the transition corridor. The uniform control approach is then used to develop reference command tracking controllers for both the longitudinal and lateral-directional dynamics. An example trajectory is simulated to demonstrate how the controller effectively transitions the aircraft from hover to forward flight and vice versa while tracking a desired trajectory.

VTOL↗
NASA NTRSDate not supplied

High-Fidelity Analysis of Lift+Cruise VTOL Urban Air Mobility Concept Aircraft

This paper presents a high-fidelity multidisciplinary analysis for the NASA lift+cruise vertical takeoff and landing urban air mobility concept aircraft. The reported simulations couple comprehensive rotorcraft aeromechanics and high-fidelity computational fluid dynamics (CFD). Aerodynamic solutions are computed on dynamic, deforming, unstructured, overset grid systems by an unsteady CFD solver, FUN3D, developed at the NASA Langley Research Center. An integrated overset-grid assembler, Yoga, is used for communications between component grids. Two turbulence models are compared for loose-coupling simulations in hover and low-speed forward flight conditions. One model is the negative variant of the one-equation Spalart-Allmaras model (SA-neg), and the other model is the SA-neg-R model adding a simple rotation correction term to the SA-neg model. It demonstrated that the rotation correction in the SA-neg-R turbulence model significantly improves resolution of secondary vortices and wake interactions for rotorcraft simulations.

CFD↗
NASA NTRS2023

High-Fidelity Analysis of Lift+Cruise VTOL Urban Air Mobility Concept Aircraft

This paper presents a high-fidelity multidisciplinary analysis for the NASA Lift+Cruise vertical takeoff and landing urban air mobility concept aircraft. The reported simulations couple comprehensive rotorcraft aeromechanics and high-fidelity computational fluid dynamics (CFD). Aerodynamic solutions are computed on dynamic, deforming, unstructured, overset grid systems by an unsteady CFD solver, FUN3D, developed at the NASA Langley Research Center. An integrated overset-grid assembler, Yoga, is used for communications between component grids. Two turbulence models are compared for loose-coupling simulations in hover and low-speed forward flight conditions. One model is the negative variant of the one-equation Spalart-Allmaras model (SA-neg), and the other model is the SA-neg-R model adding a simple rotation correction term to the SA-neg model. It demonstrated that the rotation correction in the SA-neg-R turbulence model significantly improves resolution of secondary vortices and wake interactions for rotorcraft simulations.

CFD↗
NASA NTRS1962

Linearized Theory of Wind-tunnel Jet-boundary Corrections and Ground Effect for VTOL-STOL Aircraft

A linearized theory is developed to obtain interference factors for wind tunnels and ground effect. The calculated results, presented in tabular form in NASA Technical Notes D-933, D-934, D-935, and D-936, indicate that the degree to which the wake is deflected downward has a primary effect on the magnitude of the interference. When the wake is undeflected the corrections are essentially the same as those of classical theory. When the wake is deflected severely downward, the corrections are primarily determined by the floor of the wind tunnel. Under these conditions, the corrections are, in general, much larger than those given by previously available results. Because of deformations at the lower boundary of the jet, the corrections for an open wind tunnel are uncertain. Testing at low speeds and high lift coefficients in open wind tunnels, therefore, is not recommended. Although the theory is developed expressly for single-element, vanishingly small models, methods, with sample calculations, are given for extending the results to multielement and finite span models. The theory is at least partially verified by available test data; however, complete verification would require a substantially more detailed experimental study.

V/STOL aircraft↗