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Briefs: Mechanical & Fluid Systems
Experiments on Vibration and Noise in Fuselages
A paper summarizes a continuing program of vibro-acoustic testing of two aircraft fuselage structures: (1) a 12-ft (3.7-m)-long generic aluminum test-bed cylinder that contains stiffening rings and stringers and (2) the 40-ft (12.2-m)-long fuselage of a 10-passenger turboprop airplane, made of...
Briefs: Mechanical & Fluid Systems
FoilSim is a computer program that calculates and graphically depicts information on flows of air around airfoils of various shapes. Although it is useful primarily as a teaching tool to enhance...
Briefs: Mechanical & Fluid Systems
Current proposed shapes for single-stage-to-orbit vehicles like the Lockheed-Martin X-33 and VentureStar reusable launch vehicle have extremely large base areas when compared with...
Briefs: Mechanical & Fluid Systems
A process for the fabrication of a polycrystalline diamond membrane involves chemical vapor deposition (CVD) of diamond onto a silicon substrate, followed by conventional...
Briefs: Mechanical & Fluid Systems
NASA's F-15B #836 is a two-seat version of the F-15, which is a high-performance, supersonic, all-weather fighter airplane. The F-15B is used as a test-bed aircraft for a wide variety of...
Briefs: Mechanical & Fluid Systems
Space structures in general experience free-free vibrational boundary conditions that are not readily replicable on the ground. To conduct vibration tests of such structures on Earth,...
Briefs: Mechanical & Fluid Systems
A change in the design of the engine inlets of the T-38 airplane significantly reduces takeoff distances while increasing safety margins. Although the newer inlet design (see Figure 1) is based on well-known...
Briefs: Mechanical & Fluid Systems
Some changes in the design and construction of the leading edges of metal airplane wings have shown promise as means to suppress laminar-to-turbulent flow transitions. The significance...
Briefs: Mechanical & Fluid Systems
The figure shows an oil tunnel and associated equipment used in experiments, using the full-flow-field tracking (FFFT) technique, to characterize flows in beds packed with poly (methyl...
Briefs: Mechanical & Fluid Systems
NASA Dryden Flight Research Center is supporting a Phase II Small Business Innovation Research (SBIR) contract between the U.S. Air Force Research Labs and Kelly Space & Technology (KST). KST's innovation...
Briefs: Mechanical & Fluid Systems
Direct measurement of aircraft-engine thrust by use of strain gauges offers several advantages over traditional model-based methods of calculating thrust, provided that care is...
Briefs: Mechanical & Fluid Systems
Model-Based Monitoring for Spacecraft Thruster Leakage
A report describes a method of detecting leakage in one of the 16 thrusters of the Cassini spacecraft. The detection method, implemented as part of the spacecraft flight software, is based on the fact that the three-axis rotational motion of a spacecraft is governed by the Euler's equation. The...
Briefs: Mechanical & Fluid Systems
The Perseus B remotely piloted vehicle (RPV) has achieved a record altitude for a single-engine, propeller-driven airplane of 60,260 ft (18,367 m) on June 27, 1998. The Perseus B is one of the...
Briefs: Mechanical & Fluid Systems
Streamlined fairings have been invented for housing single or multiple microphones to measure noise in flowing gases and liquids. Each fairing of this type is designed to minimize the...
Briefs: Mechanical & Fluid Systems
The figure depicts an improved apparatus for three- or four-point bending tests of stripe specimens. In a bending test, the specimen is subjected to tension along its top surface and compression along its...
Briefs: Mechanical & Fluid Systems
Using Genetic Algorithms in Spacecraft Vibration Control
Three software products are being developed to help satisfy the needs of NASA and of private industry for reconfigurable active control systems to suppress vibrations in Reusable Launch Vehicles (RLVs) and other structures. These potentially highly marketable products are the following:
The...
Briefs: Mechanical & Fluid Systems
Two techniques have been proposed (see figure) for controlling the buoyancies and thus the altitudes of robotic lifting balloons (aerobots) that would carry scientific instruments...
Briefs: Mechanical & Fluid Systems
Improved pressure-relief valves have been developed for systems that contain gases and liquids in a variety of pneumatic, hydraulic, and cryogenic applications. These valves could prove...
Briefs: Mechanical & Fluid Systems
It is not necessary to allocate valuable forebody volume to strake-deployment mechanisms.
Briefs: Mechanical & Fluid Systems
Equipping Quick-Disconnect Fittings To Detect Leaks
Quick-disconnect fittings on hoses and bellows can be equipped with sensors to detect leaks and misalignments that cause leaks. Experiments have shown that four types of sensors are effective for this purpose: force sensors, strain gauges, pressure transducers, and microphones. Of these, force...
Briefs: Mechanical & Fluid Systems
A surface-micromachining process has been devised for use in fabricating microscopic polycrystalline diamond structures (e.g., bridges and cantilevers) as integral parts...
Briefs: Mechanical & Fluid Systems
This airplane is expected to be safe from destruction by flutter instabilities.
Briefs: Power
A prototype Stirling-engine regenerator containing a matrix made of carbon-fiber-based composite materials has been developed. The concept underlying this development effort is one of...
Briefs: Mechanical & Fluid Systems
A flutterometer is being developed for use as a data-analysis tool for flight flutter testing. The tool is based on an on-line implementation of a robust flutter-analysis technique, called the "* method," that...
Briefs: Mechanical & Fluid Systems
A mathematical model represents the dynamic response of a pressure sensor that (a) comprises a transducer connected to a pressure-sensing port via a pneumatic tube and (b) is operated under...
Briefs: Mechanical & Fluid Systems
Improved Mufflers for General Aviation
Innovative designs of mufflers for engines of small airplanes have been investigated in an effort to satisfy conflicting demands to maximize the reduction of exhaust noise while minimizing back pressure, size, and weight. Automotive-type muffler designs are not suitable for this purpose because they entail...
Briefs: Mechanical & Fluid Systems
An acoustic-radiation-pressure phased array (ARPPA) is undergoing development at Lewis Research Center. ARPPAs are envisioned as general-purpose, nonintrusive tools for manipulating both liquids...
Briefs: Mechanical & Fluid Systems
Structural Analysis/Design (STRAND) and Neural Net Computation (NETCOM) are developmental modular computer programs that exploit the speedup afforded by parallel and neural-network...
Briefs: Mechanical & Fluid Systems
Acoustic-radiation pressure can be used to improve performance in the dispensing of liquid drops into gases or vacuum and in dispensing gas bubbles into liquids. In a typical application...
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