Search NASA⌕ Search

SEARCH · Search NASA

Results for “Rotary Wing”

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

Active-Twist Rotor Control Applications for UAVs

The current state-of-the-art in active-twist rotor control is discussed using representative examples from analytical and experimental studies, and the application to rotary-wing UAVs is considered. Topics include vibration and noise reduction, rotor performance improvement, active blade tracking, stability augmentation, and rotor blade de-icing. A review of the current status of piezoelectric fiber composite actuator technology, the class of piezoelectric actuators implemented in active-twist rotor systems, is included.

Wilbur, Matthew L.↗

Deployment and Evaluation of the Helicopter In-Flight Tracking System (HITS)

The Gulf of Mexico airspace has two major operating regions: low altitude offshore (below 7,000 ft) and high altitude oceanic (above 18,000 ft). Both regions suffer significant inefficiencies due to the lack of continuous surveillance during Instrument Flight Rules operations. Provision of surveillance in the offshore region is hindered by its low-altitude nature, which makes coverage by conventional radars economically infeasible. Significant portions of the oceanic sectors are inaccessible to shore-based sensors, as they are beyond line-of-sight. Two emerging surveillance technologies were assessed that are relatively low cost and can be deployed on offshore platforms Wide Area Multilateration and Automatic Dependent Surveillance Broadcast. Performance criteria were formulated using existing FAA specifications. Three configurations were developed and deployed representative of systems serving full-size and reduced-sized domestic terminal areas and an en-route/oceanic region. These configurations were evaluated during nine flight test periods using fixed- and rotary-wing aircraft.

Daskalakis, Anastasios↗

Realizing the Dream of Flight: Biographical Essays in Honor of the Centennial of Flight, 1903-2003

While growing up in Cedar Rapids, Iowa, Milton Wright, The Wright Brothers Father, liked to purchase toys for his sons that he hoped would stimulate their imagination. One of the most memorable gifts was a toy helicopter that was designed by the French aeronautical experimenter Alphonse P naud. Milton gave his sons this gift in 1878, and, though it was a simple device with a stick bound to a four-blade rotor set in a spindle, it had the intended effect it caused them to dream. Twenty-five years separated the gift of this toy and their invention of the airplane, yet the Wright brothers were convinced it had exerted an important influence. Tom Crouch argued in The Bishop's Boys that toys like these perfectly illustrated the significance of play for technological innovation. He wrote, rotary-wing toys were to intrigue and inspire generations of children, a few of whom would, as adults, attempt to realize the dream of flight for themselves. If the first powered flight on 17 December 1903 represented a childhood dream realized, it was only the first step in the rapid evolution of the airplane from their flimsy kite-like contraption of wood and cloth to jet airliners and rockets in space. And, as extraordinary as the achievement of powered flight seemed in 1903, before the end of the century, space travel also would become a dream realized. Soviet astronaut Yuri Gagarin first circumnavigated Earth in April 1961, and, eight years later, American astronauts took the first steps for humankind on the Moon. It is with great pleasure that we introduce Realizing the Dream: Biographical Essays in Honor of the Centennial of Flight. These essays in celebration of the Wright brothers first flight 100 years ago grew out of presentations by a group of prominent scholars in 2003 at a conference sponsored by the NASA History Division and held at the Great Lakes Science Center in Cleveland, Ohio. The volume focuses on the careers of some of the many men and women who helped to realize the dream of flight both through the atmosphere and beyond.

Dawson, Virginia P.↗

Civilian Aeronautical Futures - The Responsibly Imaginable

Since 1940 Aeronautics has had an immense impact upon Global Human lifestyles and affairs - in both the Civilian and Military arenas. During this period Long distance Train and Ship passenger transport were largely supplanted by Air Travel and Aviation assumed a dominant role in warfare. The early 1940 s to the mid 1970 s was a particularly productive period in terms of Aeronautical Technology. What is interesting is that, since the mid 1970 s, the rate of Aeronautical Technological Progress has been far slower, the basic technology in nearly all of our current Aero Systems dates from the mid 70 s or earlier. This is especially true in terms of Configuration Aerodynamics, Aeronautics appears to have "settled" on the 707, double delta and rotary wing as the approach of choice for Subsonic long haul, supersonic cruise and VTOL respectively. Obviously there have been variants and some niche digression from this/these but in the main Aeronautics, particularly civilian Aeronautics, has become a self-professed "mature", Increasingly "Commodity", Industry. The Industry is far along an existing/deployed technology curve and focused, now for decades, on incremental/evolutionary change - largely Appliers vs. developers of technology. This is, of course, in sharp contrast to the situation in the early-to-later 20th century where Aeronautics was viewed as A Major Technological Engine, much the way IT/Bio/Nano/Energetics/Quantum Technologies are viewed today. A search for Visionary Aeronautical "Futures" papers/projections indicates a decided dearth thereof over the last 20 plus years compared to the previous quarter Century. Aeronautics is part of Aerospace and Aerospace [including Aeronautics] has seen major cutbacks over the last decades. Some numbers for the U.S. Aerospace Industry serve as examples. Order of 600,000 jobs lost, with some 180,000 more on the block over the next 10 years. Approximately 25% of the Aerospace workforce is eligible to retire and the average Engineer age is in the mid-50 s. Firms such as Microsoft, Intel and Walmart are individually capitalized at a factor of 4 or more than the Aerospace industry as a whole. Aerospace Research levels are in the less than 5% range in terms of overall U.S. Research Investments.

Bushnell, Dennis M.↗

Enhanced Rescue Lift Capability

The evolving and ever-increasing demands of emergency response and disaster relief support provided by rotorcraft dictate, among other things, the development of enhanced rescue lift capability for these platforms. This preliminary analysis is first-order in nature but provides considerable insight into some of the challenges inherent in trying to effect rescue using a unique form of robotic rescue device deployed and operated from rotary-wing aerial platforms.

Young, Larry A.↗

Biomimetic mechanism for micro aircraft

A biomimetic pitching and flapping mechanism including a support member, at least two blade joints for holding blades and operatively connected to the support member. An outer shaft member is concentric with the support member, and an inner shaft member is concentric with the outer shaft member. The mechanism allows the blades of a small-scale rotor to be actuated in the flap and pitch degrees of freedom. The pitching and the flapping are completely independent from and uncoupled to each other. As such, the rotor can independently flap, or independently pitch, or flap and pitch simultaneously with different amplitudes and/or frequencies. The mechanism can also be used in a non-rotary wing configuration, such as an ornithopter, in which case the rotational degree of freedom would be suppressed.

Pines, Darryll J.↗

System and method for improved rotor tip performance

The present invention discloses systems and methods for the performance enhancement of rotary wing aircraft through reduced torque, noise and vibration. In one embodiment, a system includes a sail having an aerodynamic shape positioned proximate to a tip of the rotor blade. An actuator may be configured to rotate the sail relative to the blade tip. a A control system receives information from a rotorcraft system and commands the actuator to rotate the sail to a predetermined favorable rotor blade operating condition. In another embodiment, a method includes configuring the rotorcraft in a selected flight condition, communicating input signals to a control system operable to position sails coupled to tips of blades of a rotor assembly, processing the input signals according to a constraint condition to generate sail positional information, and transferring the sail positional information to the sail.

Bussom, Richard↗

Vertical Drop Testing and Analysis of the WASP Helicopter Skid Gear

Human occupant modeling and injury risk assessment have been identified as areas of research for improved prediction of rotorcraft crashworthiness within the NASA Aeronautics Program's Subsonic Rotary Wing Project. As part of this effort, an experimental program was conducted to assess the impact performance of a skid gear for use on the WASP kit-built helicopter, which is marketed by HeloWerks, Inc. of Hampton, Virginia. Test data from a drop test at an impact velocity of 8.4 feet-per-second were used to assess a finite element model of the skid gear test article. This assessment included human occupant analytic models developed for execution in LS-DYNA. The test article consisted of an aluminum skid gear mounted beneath a steel plate. A seating platform was attached to the upper surface of the steel plate, and two 95th percentile Hybrid III male Aerospace Anthropomorphic Test Devices (ATDs) were seated on the platform and secured using a four-point restraint system. The goal of the test-analysis correlation is to further the understanding of LS-DYNA ATD occupant models and responses in the vertical (or spinal) direction. By correlating human occupant experimental test data for a purely vertical impact with the LS-DYNA occupant responses, improved confidence in the use of these tools and better understanding of the limitations of the automotive-based occupant models for aerospace application can begin to be developed.

Fuchs, Yvonne T.↗

Comparison of ALE and SPH Simulations of Vertical Drop Tests of a Composite Fuselage Section into Water

Simulation of multi-terrain impact has been identified as an important research area for improved prediction of rotorcraft crashworthiness within the NASA Subsonic Rotary Wing Aeronautics Program on Rotorcraft Crashworthiness. As part of this effort, two vertical drop tests were conducted of a 5-ft-diameter composite fuselage section into water. For the first test, the fuselage section was impacted in a baseline configuration without energy absorbers. For the second test, the fuselage section was retrofitted with a composite honeycomb energy absorber. Both tests were conducted at a nominal velocity of 25-ft/s. A detailed finite element model was developed to represent each test article and water impact was simulated using both Arbitrary Lagrangian Eulerian (ALE) and Smooth Particle Hydrodynamics (SPH) approaches in LS-DYNA, a nonlinear, explicit transient dynamic finite element code. Analytical predictions were correlated with experimental data for both test configurations. In addition, studies were performed to evaluate the influence of mesh density on test-analysis correlation.

Jackson, Karen E.↗

Rotor Airloads Prediction Using Unstructured Meshes and Loose CFD/CSD Coupling

The FUN3D unsteady Reynolds-averaged Navier-Stokes solver for unstructured grids has been modified to allow prediction of trimmed rotorcraft airloads. The trim of the rotorcraft and the aeroelastic deformation of the rotor blades are accounted for via loose coupling with the CAMRAD II rotorcraft computational structural dynamics code. The set of codes is used to analyze the HART-II Baseline, Minimum Noise and Minimum Vibration test conditions. The loose coupling approach is found to be stable and convergent for the cases considered. Comparison of the resulting airloads and structural deformations with experimentally measured data is presented. The effect of grid resolution and temporal accuracy is examined. Rotorcraft airloads prediction presents a very substantial challenge for Computational Fluid Dynamics (CFD). Not only must the unsteady nature of the flow be accurately modeled, but since most rotorcraft blades are not structurally stiff, an accurate simulation must account for the blade structural dynamics. In addition, trim of the rotorcraft to desired thrust and moment targets depends on both aerodynamic loads and structural deformation, and vice versa. Further, interaction of the fuselage with the rotor flow field can be important, so that relative motion between the blades and the fuselage must be accommodated. Thus a complete simulation requires coupled aerodynamics, structures and trim, with the ability to model geometrically complex configurations. NASA has recently initiated a Subsonic Rotary Wing (SRW) Project under the overall Fundamental Aeronautics Program. Within the context of SRW are efforts aimed at furthering the state of the art of high-fidelity rotorcraft flow simulations, using both structured and unstructured meshes. Structured-mesh solvers have an advantage in computation speed, but even though remarkably complex configurations may be accommodated using the overset grid approach, generation of complex structured-mesh systems can require months to set up. As a result, many rotorcraft simulations using structured-grid CFD neglect the fuselage. On the other hand, unstructured-mesh solvers are easily able to handle complex geometries, but suffer from slower execution speed. However, advances in both computer hardware and CFD algorithms have made previously state-of-the-art computations routine for unstructured-mesh solvers, so that rotorcraft simulations using unstructured grids are now viable. The aim of the present work is to develop a first principles rotorcraft simulation tool based on an unstructured CFD solver.

Biedron, Robert T.↗

Progress in NASA Rotorcraft Propulsion

This presentation reviews recent progress made under NASA s Subsonic Rotary Wing (SRW) propulsion research activities. Advances in engines, drive systems and optimized propulsion systems are discussed. Progress in wide operability compressors, modeling of variable geometry turbine performance, foil gas bearings and multi-speed transmissions are presented.

DellaCorte, Christopher↗

Gear Windage Modeling Progress - Experimental Validation Status

In the Subsonics Rotary Wing (SRW) Project being funded for propulsion work at NASA Glenn Research Center, performance of the propulsion system is of high importance. In current rotorcraft drive systems many gearing components operate at high rotational speed (pitch line velocity > 24000 ft/ min). In our testing of high speed helical gear trains at NASA Glenn we have found that the work done on the air - oil mist within the gearbox can become a significant part of the power loss of the system. This loss mechanism is referred to as windage. The effort described in this presentation is to try to understand the variables that affect windage, develop a good experimental data base to validate, the analytical project being conducted at Penn State University by Dr. Rob Kunz under a NASA SRW NRA. The presentation provides an update to the status of these efforts.

Kunz, Rob↗

Small Autonomous Aircraft Servo Health Monitoring

Small air vehicles offer challenging power, weight, and volume constraints when considering implementation of system health monitoring technologies. In order to develop a testbed for monitoring the health and integrity of control surface servos and linkages, the Autonomous Aircraft Servo Health Monitoring system has been designed for small Uninhabited Aerial Vehicle (UAV) platforms to detect problematic behavior from servos and the air craft structures they control, This system will serve to verify the structural integrity of an aircraft's servos and linkages and thereby, through early detection of a problematic situation, minimize the chances of an aircraft accident. Embry-Riddle Aeronautical University's rotary-winged UAV has an Airborne Power management unit that is responsible for regulating, distributing, and monitoring the power supplied to the UAV's avionics. The current sensing technology utilized by the Airborne Power Management system is also the basis for the Servo Health system. The Servo Health system measures the current draw of the servos while the servos are in Motion in order to quantify the servo health. During a preflight check, deviations from a known baseline behavior can be logged and their causes found upon closer inspection of the aircraft. The erratic behavior nay include binding as a result of dirt buildup or backlash caused by looseness in the mechanical linkages. Moreover, the Servo Health system will allow elusive problems to be identified and preventative measures taken to avoid unnecessary hazardous conditions in small autonomous aircraft.

Quintero, Steven↗

Developing Soil Models for Dynamic Impact Simulations

This paper describes fundamental soils characterization work performed at NASA Langley Research Center in support of the Subsonic Rotary Wing (SRW) Aeronautics Program and the Orion Landing System (LS) Advanced Development Program (ADP). LS-DYNA(Registered TradeMark)1 soil impact model development and test-analysis correlation results are presented for: (1) a 38-ft/s vertical drop test of a composite fuselage section, outfitted with four blocks of deployable energy absorbers (DEA), onto sand, and (2) a series of impact tests of a 1/2-scale geometric boilerplate Orion capsule onto soil. In addition, the paper will discuss LS-DYNA contact analysis at the soil/structure interface, methods used to estimate frictional forces, and the sensitivity of the model to density, moisture, and compaction.

Fasanella, Edwin L.↗

Navier-Stokes Simulation of a Heavy Lift Slowed-Rotor Compound Helicopter Configuration

Time accurate numerical simulations were performed using the Reynolds-averaged Navier-Stokes (RANS) flow solver OVERFLOW for a heavy lift, slowed-rotor, compound helicopter configuration, tested at the NASA Langley 14- by 22-Foot Subsonic Tunnel. The primary purpose of these simulations is to provide support for the development of a large field of view Particle Imaging Velocimetry (PIV) flow measurement technique supported by the Subsonic Rotary Wing (SRW) project under the NASA Fundamental Aeronautics program. These simulations provide a better understanding of the rotor and body wake flows and helped to define PIV measurement locations as well as requirements for validation of flow solver codes. The large field PIV system can measure the three-dimensional velocity flow field in a 0.914m by 1.83m plane. PIV measurements were performed upstream and downstream of the vertical tail section and are compared to simulation results. The simulations are also used to better understand the tunnel wall and body/rotor support effects by comparing simulations with and without tunnel floor/ceiling walls and supports. Comparisons are also made to the experimental force and moment data for the body and rotor.

Allan, Brian G.↗

HART-II Acoustic Predictions using a Coupled CFD/CSD Method

This paper documents results to date from the Rotorcraft Acoustic Characterization and Mitigation activity under the NASA Subsonic Rotary Wing Project. The primary goal of this activity is to develop a NASA rotorcraft impulsive noise prediction capability which uses first principles fluid dynamics and structural dynamics. During this effort, elastic blade motion and co-processing capabilities have been included in a recent version of the computational fluid dynamics code (CFD). The CFD code is loosely coupled to computational structural dynamics (CSD) code using new interface codes. The CFD/CSD coupled solution is then used to compute impulsive noise on a plane under the rotor using the Ffowcs Williams-Hawkings solver. This code system is then applied to a range of cases from the Higher Harmonic Aeroacoustic Rotor Test II (HART-II) experiment. For all cases presented, the full experimental configuration (i.e., rotor and wind tunnel sting mount) are used in the coupled CFD/CSD solutions. Results show good correlation between measured and predicted loading and loading time derivative at the only measured radial station. A contributing factor for a typically seen loading mean-value offset between measured data and predictions data is examined. Impulsive noise predictions on the measured microphone plane under the rotor compare favorably with measured mid-frequency noise for all cases. Flow visualization of the BL and MN cases shows that vortex structures generated in the prediction method are consist with measurements. Future application of the prediction method is discussed.

Boyd, D. Douglas, Jr.↗

Smart Rotorcraft Field Assistants for Terrestrial and Planetary Science

Field science in extreme terrestrial environments is often difficult and sometimes dangerous. Field seasons are also often short in duration. Robotic field assistants, particularly small highly mobile rotary-wing platforms, have the potential to significantly augment a field season's scientific return on investment for geology and astrobiology researchers by providing an entirely new suite of sophisticated field tools. Robotic rotorcraft and other vertical lift planetary aerial vehicle also hold promise for supporting planetary science missions.

Young, Larry A.↗

Gas Turbine Characteristics for a Large Civil Tilt-Rotor (LCTR)

In support of the Fundamental Aeronautics Program, Subsonic Rotary Wing Project; an engine system study has been undertaken to help define and understand some of the major gas turbine engine parameters required to meet performance and weight requirements as defined by earlier vehicle system studies. These previous vehicle studies will be reviewed to help define gas turbine performance goals. Assumptions and analysis methods used will be described. Performance and weight estimates for a few conceptual gas turbine engines meeting these requirements will be given and discussed. Estimated performance for these conceptual engines over a wide speed variation (down to 50 percent power turbine rpm at high torque) will be presented. Finally, areas needing further effort will be suggested and discussed.

Snyder, Christopher A.↗