15,086 research outputs found
Thrust vector control apparatus Patent
Thrust vector control by secondary injection of fluid into rocket nozzle flow field to separate exhaust flo
Kinetic-energy absorber employs frictional force between mating cylinders
A kinetic energy absorbing device uses a series of coaxial, mating cylindrical surfaces. These surfaces have high frictional resistance to relative motion when axial impact forces are applied. The device is designed for safe deceleration of vehicles impacting on landing surfaces
Non-reusuable kinetic energy absorber Patent
Non-reusable kinetic energy absorber for application in soft landing of space vehicle
Variable-area nozzle automatically controls fluid flow
Simple, passive nozzle requires no active control system to vary injection area. Injection area changes with changing pressure, thereby allowing greater flow as pressure increases. As pressure drop across nozzle is decreased, spring action of segments causes them to move inward, decreasing the flow area
Investigations of lunar sampling and sample return methods
Lunar soil sampling and packaging to minimize physical damage and contaminatio
Noise from turbomachinery
A review is made of turbomachinery noise from turbofan engines as typified by fan noise. The mechanisms and theories of fan noise are reviewed and concepts for its reduction, including acoustic suppression are discussed. Correlations of the overall noise data from several full-scale fans tested at NASA-Lewis Research Center are presented as indicative of the current state-of-the-art. Estimates are presented to show economics versus reduced noise for two quieted experimental engines, one with subsonic and one with supersonic fan tip speed. Finally, some concepts that may have the potential to reduce fan noise are indicated
Submerged gas injector expels cryogenic liquids from tanks
Vaporizing small portion of cryogenic liquid into pressurizing gas reduces amount of pressurizing gas required to expel cryogenic liquid from tank. Specific example of injecting helium gas, stored at same temperature of liquid hydrogen, through submerged porous plate directly into liquid hydrogen is described
WIMP searches with gamma rays in the Fermi era: challenges, methods and results
The launch of the gamma-ray telescope Fermi Large Area Telescope (Fermi-LAT)
started a pivotal period in indirect detection of dark matter. By outperforming
expectations, for the first time a robust and stringent test of the paradigm of
weakly interacting massive particles (WIMPs) is within reach. In this paper, we
discuss astrophysical targets for WIMP detection and the challenges they
present, review the analysis tools which have been employed to tackle these
challenges, and summarize the status of constraints on and the claimed
detections in the WIMP parameter space. Methods and results will be discussed
in comparison to Imaging Air Cherenkov Telescopes. We also provide an outlook
on short term and longer term developments.Comment: 72 pages, 7 figures, Invited review for Journal of Experimental and
Theoretical Physics,v3: added a few references, addressed referee comment
A resonance-tube igniter for hydrogen-oxygen rocket engines
Resonance-tube igniter for hydrogen-oxygen rocket engine
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