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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.

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At least 1,153 records · Page 64

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DOE OSTI2025

Towards an intuitive application of WEC control co-design

A simple co-design example in a reduced parameter space is presented for an oscillating flap device. Initially, the WEC geometry and mass properties are considered along with drivetrain gear ratio, inertia, motor constant and stiffness under both PI and optimal control. This parameter space is reduced to those to which performance is most sensitive for a fixed geometry. The gear ratio, drivetrain stiffness, and flap mass are found to be the most impactful design criteria as they can create orders of magnitude variations in power performance. The performance of the optimized system is compared with several sub-optimal variants in terms of electrical and mechanical power capture, transmission coefficients, and transducer power gain. Notably, though substantial power capture improvements are demonstrated when an optimal controller is employed, this power capture remains sensitive to appropriate selections of drivetrain and flap design parameters, implying that control co-design procedures remain necessary for high-performing WECs. Furthermore, a number of practical caveats and extensions to the presented co-design methodology are suggested, including the characterization of system static friction, especially in the presence of high gear ratios.

Control co-design↗

DOE OSTI2022

Engineering A Low-Cost Kelp Aquaculture System for Community-Scale Seaweed Farming at Nearshore Exposed Sites via User-Focused Design Process

For over 50 years, government fishery agencies have recognized the need to transition excess fishing capacity in coastal waters to aquaculture. For the most part, investment strategies to move wild capture and harvest efforts into aquaculture have failed since the technology and capital expense for entry, such as large fish pens, was not conducive for acceptance. In contrast, low trophic level aquaculture of shellfish and seaweeds is suitable as an addition to the livelihoods of seasonal fishing communities and to those displaced by fishery closures, especially if vessels and gear can be designed around existing fishing infrastructures, thus allowing fishers to maintain engagement with their primary fishery, while augmenting income via aquaculture. In this study, an inexpensive, lightweight, and highly mobile gear for kelp seaweed farming was developed and tested over a 3-year period in southern Maine, USA. The system was different from existing kelp farming operations used in nearshore waters that use low-scope mooring lines, and heavy, deadweight anchors. Instead, a highly mobile, easy to deploy system using lightweight gear was designed for exposed conditions. The entire system fit into fish tote boxes and was loadable onto a standard pickup truck. The seaweed system had small but efficient horizontal drag embedment anchors connected to a chain catenary and pretensioned with simple subsurface flotation. The system was able to be deployed and removed in less than 4 h by a crew of three using a 10 m vessel and produced a harvest of 12.7 kg/m over an 8-month fall-winter growth period. The target group for this seaweed research and development effort were coastal fishing communities who move seasonally into non-fishing occupations in service industries, such as construction, retail, etc. An economic assessment suggests farmers would realize an 8% return on investment after3 years and $13.50/h greater income as compared to a non-farming off season job at minimum wage. This low-cost seaweed farming system for fall-winter operations fits well into a “livelihood” strategy for fishing families who must work multiple jobs in the offseason when their main fishery is unavailable.

St-Gelais, Adam T.↗

NASA NTRS1971

A preliminary study of containment concepts for aircraft landing on elevated STOL-ports

A preliminary study of containment systems for aircraft landing on elevated STOL-ports was conducted as part of an overall study of human acceptance problems associated with STOL operations. The study included a survey and feasibility study of different concepts and a computer analysis of four arrestment systems. The principal conclusion was that a system referred to as the FAA system appears to offer the greatest promise. In this system, standard arresting gear cables are stretched across the roof-top, at roughly 100-foot intervals, but are shielded over the 100-foot-wide primary landing strip. Thus a pilot can land with an arresting hook down, but will not contact the cable unless he swerves off the landing strip, either because he has made a bad landing, or because his landing gear has failed. It was also noted that a suitable curb or guard rail should be developed. Presently available arresting gears and nylon net barriers were considered satisfactory for the overshoot problem.

Haviland, J. K.↗

NASA NTRS1972

Analysis of legged landers for the survivable soft landing of instrument payloads.

Two methods of analysis have been developed for legged planetary landers. The first of these, the Large Displacement Gear Analysis, is a design tool for statically determining the large displacement stroking behavior, energy absorption characteristics, and internal load distributions in a single gear. The second, the Landing Dynamics Analysis, predicts the spatial landing dynamics of a legged lander. Effects of structural flexibility, elastic-plastic gear load characteristics, and soil properties on the loads, motions, and stability of the lander may be determined. Validation of the analytical techniques is accomplished through comparison of predicted results and experimental data obtained during a model test program.

Laurenson, R. M.↗

NASA NTRS1974

Rotating and positive-displacement pumps for low-thrust rocket engines. Volume 1: Pump Evaluation and design

Rotating and positive displacement pumps of various types were studied for pumping liquid fluorine for low-thrust, high-performance rocket engines. Included in the analysis were: centrifugal, pitot, Barske, Tesla, drag, gear, vane, axial piston, radial piston, diaphragm, and helirotor pump concepts. The centrifugal pump and the gear pump were selected and these were carried through detailed design and fabrication. Mechanical difficulties were encountered with the gear pump during the preliminary tests in Freon-12. Further testing and development was therefore limited to the centrifugal pump. Tests on the centrifugal pump were conducted in Freon-12 to determine the hydrodynamic performance and in liquid fluorine to demonstrate chemical compatibility.

Macgregor, C.↗

NASA NTRS1973

Use of the dispersion ratio in estimating the nonlinear properties of an object of diagnosis

An experimental investigation for estimating the nonlinearity of a diagnostic object was carried out on a single-stage, spur gear reducer. The linearity of the properties of spur gearing (including the linearity of its mode of operation) was tested. Torsional vibrations of the driven wheel and transverse (to the meshing plane) vibrations of the drive wheel on its support were taken as the two outputs of the object to be analyzed. The results of the investigation showed that the degree of nonlinearity of a reducing gear is essentially connected with its operating mode, so that different mathematical models of it can correspond to different values of the system parameters.

Balitskiy, F. Y.↗

NASA NTRS1974

Coherent optical noise suppression device

The present work describes a scheme for a noise suppression system to be used with an afocal coherent optical data processor. The noise averaging scheme is based on the simple principle of moving input and output film planes together during exposure; the noise pattern remains stationary while the desired (filtered) image moves through it. The noise suppression system consists of a drive motor, right-angle gear box, reversing gear assemblage, right-angle gear drive, and micrometer adjusting translation tables. The device was tested by using a Sayce target containing fundamental spatial frequencies from 5 lines/mm to 100 lines/mm as the input signal. The output was photographed on Pan-X 35-mm film with and without the noise suppression system in operation. Microdensitometer scans of the exposed output film show that without noise averaging, resolution is good to about 80 lines/mm, while with noise averaging, it is good to about 35 lines/mm. A brief analysis of errors in the mechanical parts of the system reponsible for the upper limit of resolution is presented.

Horner, J. L.↗

NASA NTRS1974

Orthotic arm joint

An improved orthopedic (orthotic) arm joint that can be used in various joint of mechanical arms is described. The arm joints includes a worm, which is coupled to an electric motor for rotating a worm gear carried within a rotatable housing. The worm gear is supported on a thrust bearing and the rotatable housing is supported on a radial thrust bearing. A bolt extends through the housing, bearings, and worm gear for securing the device together. A potentiometer extends through the bolt, and is coupled to the rotatable housing for rotating therewith, so as to produce an electrical signal indicating the angular position of the rotatable housing.

Dane, D. H.↗

NASA NTRS1975

Investigation of space shuttle vehicle 140C configuration orbiter (model 16-0) wheel well pressure loads in the Rockwell International 7.75 x 11 foot wind tunnel (OA143)

Experimental aerodynamic investigations were conducted on a sting mounted .0405-scale representation of the 140C outer mold line space shuttle orbiter configuration in the Rockwell International 7.75 x 11.00 foot low speed wind tunnel. The primary test objectives were to define the orbiter wheel well pressure loading and its effects on landing gear thermal insulation and to investigate the pressure environment experienced by both the horizontal flight nose probe and air vent door probes. Steady state and dynamic pressure values were recorded in the orbiter nose gear well, left main landing gear well, horizontal flight nose probe, and both left and right air vent door probe. All steady state pressure levels were measured by Statham differential pressure transducers while dynamic pressure levels were recorded by Kulite high frequency response pressure sensors.

Mennell, R. C.↗

NASA NTRS1975

Diagnostic calculations of airframe-radiated noise

Methods of calculating airframe noise due to the following components are presented: wings and stabilizers, flaps, landing gear 'self-noise', landing gear bay (wheel well) oscillations, separated flow interaction with edges of cavities, and doors associated with gear deployment. The predominant source mechanisms were dipole-like in nature, being related to the local fluctuating aerodynamic forces on struts, airfoil edges, cavity edges, etc. Available data are converted into semiempirical prediction methods to enable a tentative rank ordering of noise sources. A sample application of these prediction procedures is carried out for a typical CTOL passenger jet using actual aircraft parameters, where available.

Hayden, R. E.↗

NASA NTRS1975

Ditching investigation of a 1/20-scale model of the space shuttle orbiter

The ditching characteristics of the space shuttle orbiter were examined. Tests were made with a 1/20-scale model in order to determine behavior patterns and accelerations imparted to the ditching vehicle. Ditchings were made with different configurations of weight and gear position. Also the effects of different water surface conditions were investigated. The test results indicated that the favorable conditions for ditching usually involve a landing attitude of 12 deg. Smooth ditchings were always associated with the landing-gear retracted and never with the landing-gear extended. Higher landing mass, generally, resulted in higher acceleration values in both the longitudinal and normal directions. Surface waves tend to increase the pitch accelerations but at the same time tend to reduce the accelerations in the longitudinal and normal directions.

Thomas, W. L.↗

NASA NTRS1977

Ground effects and control effectiveness tests of a .095 scale powered model of a modified T-39 lift/cruise fan V/STOL research airplane

Wind tunnel test data are analysed to determine ground effects and the effectiveness of the aerodynamic control surfaces to provide a technology base for a Navy type A V/STOL airplane. Three 14CM (5.5 inch) turbopowered simulators were used to power the model which was tested primarily in the following configurations: (1) VTOL with flaps deployed, gear down, and engines tilted to 80 deg, 90 deg, and 95 deg, (2) STOL with flap and gear down and engines tilted to 50 deg; and (3) Loiter with flaps and gear up and L/C nacelles off. Data acquired during the tests are included as an appendix.

Dawson, C. R.↗

NASA NTRS1978

Airframe noise of the DC-9-31

Airframe noise measurements are reported for the DC-9-31 aircraft flown at several speeds and with a number of flap, landing gear, and slat extension configurations. The data are corrected for wind effects, atmospheric attenuation, and spherical divergence, and are normalized to a 1 meter acoustic range. The sound pressure levels are found to vary approximately as the fifth power of flight velocity. Both lift and drag dipoles exist as a significant part of the airframe noise. The sideline data imply that a significant side-force dipole exists only for the flap- and gear-down configurations; for others, the data imply the existence of only the lift and drag dipoles. The data are compared with airframe noise predictions using the drag element and the data analysis methods. Although some of the predictions are good, further work is needed to refine the methods, particularly for the flap- and gear-down configurations.

Bauer, A. B.↗

NASA NTRS1979

Concept for a large multi-mission amphibian aircraft

A very large aircraft has been proposed for meeting both civil cargo and military transport needs for 1995 and beyond. The concept includes a wide noncircular fuselage cross section with a low wing, thick inner wing section, fuselage-mounted engines, and an air cushion landing gear. The civil freighter operates independently of congested passenger airports, using sheltered water as a runway and a waterfront land site for parking and ground operations. The military transport can operate from a wide variety of surfaces and temporary bases. The air cushion landing gear weighs substantially less than conventional gear and permits the use of extended takeoff distance resulting in improved payload/gross weight ratio.

Vaughan, J. C., III↗

NASA NTRS1981

Torque-wrench extension

Torque-wrench extension makes it easy to install and remove fasteners that are beyond reach of typical wrenches or are located in narrow spaces that prevent full travel of wrench handle. At same time, tool reads applied torque accurately. Wrench drive system, for torques up to 125 inch-pounds, uses 2 standard drive-socket extensions in aluminum frame. Extensions are connected to bevel gear that turns another bevel gear. Gears produce 1:1 turn ratio through 90 degree translation of axis of rotation. Output bevel has short extension that is used to attach 1/4-inch drive socket.

Peterson, D. H.↗

NASA NTRS1981

Self-lubricating gearset

Gearset fabricated from molybdenum sulfide filled polyimide allows attention-free operation in vacuum and at extreme temperatures. Ring gear drives pinion gear on shaft in skewed-axis arrangement. Because loads are shared among multiple meshing teeth, self-lubricating material is strong enough to accomodate high gear ratio.

Binge, D. S.↗

NASA NTRS1979

Load support system analysis high speed input pinion configuration

An analysis and a series of computerized calculations were carried out to explore competing prototype design concepts of a shaft and two taper-roller bearings systems to support the high-speed input pinion of an advanced commercial helicopter transmission. The results were used to evaluate designs both for a straddle arrangement where the pinion gear is located between the bearings and for a cantilever arrangement where the pinion is outboard of the two bearings. Effects of varying parameters including applied gear load, preload, wall thickness, interference fits, bearing spacing and pinion gear location on system rigidity, load distribution and bearing rating life were assessed. A comparison of the bearing load distributions for these designs demonstrated that the straddle more equally distributes both radial and axial loads. The performance of these designs over a range of shaft rotational speeds, with lubrication and friction effects included, is also discussed.

Gassel, S. S.↗

NASA NTRS1982

Improved Clothing for Firefighters

Application of space technology should reduce incidence of injuries, heat exhaustion, and fatigue in firefighters. Using advanced materials and design concepts of aerospace technology, protective gear was fabricated and tested for the heat, face, torso, hand and foot. In tests, it was found that new gear protects better than conventional firefighter gear, weighs 40 percent less, and reduces wearer's energy expenditure by 25 percent.

Abeles, F. J.↗