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Mechanical Engineering. 2013;135(08):30-35. doi:10.1115/1.2013-AUG-1.
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This paper explores the use of immersive computing or virtual reality throughout a product design, assembly, and disassembly. Virtual reality or immersive computing creates a sense of presence for participants through devices that stimulate the senses. Immersive computing technology goes a step further by allowing the participant to interact with computer-generated models or environments rather than to passively view a screen. The technology is a collection of hardware and software that lets the participant explore digitally created objects within a three-dimensional space. Immersive computing presents a sharp contrast to existing two-dimensional computer interfaces used with computer-aided design (CAD) software programs. In order to illustrate the use of immersive computing in product design, research projects focus on using the technology to explore uncertainty in making design decisions. Industry is realizing the benefits of increased communication and deeper understanding of complex design issues through the use of immersive computing. Experts believe that when every engineer’s desktop includes immersive computing technology, the results will be better products produced more economically and with increased national competitiveness.

Commentary by Dr. Valentin Fuster
Mechanical Engineering. 2013;135(08):44-49. doi:10.1115/1.2013-AUG-2.
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This article reviews various tools that are evolving to help engineers work with complex composite materials. Specialized composite analysts are needed to help find the best material for a particular use and to determine if it can be manufactured with the chosen material and in a particular shape. The Falcon Heavy spaceflight system is planned to launch on a SpaceX-designed rocket engine. As composite materials are lighter than metal, SpaceX engineers realized that composites could improve the strength-to-weight ratio of its materials. In order to help engineers choose the best composite for the design, the software system contains a large library of material models that designers can use to explore a composite material and determine how it might behave under a variety of circumstances. Predicting how the cracks will affect the part long-term still cannot be done within software packages and must be prototyped.

Commentary by Dr. Valentin Fuster
Mechanical Engineering. 2013;135(08):50-57. doi:10.1115/1.2013-AUG-3.
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This article is a study of engineering concepts behind design and functioning of SailRocket, an innovative sailboat, and other ongoing experiments on different sailboats. Researchers believe that to push sail technology to the extremes of performance requires disregarding the child’s eye view of a sailboat. Conceptually, the SailRocket owes more to aircraft and wind turbines than it does to traditional yachts. The engineering concepts behind the sailboat design are: the hydrofoils lifting up as the wind tries to push the mast over; the sails on one side of the center of mass and the sailor on the other; the force of the water on the keel resisting the windward drift of the boat. According to the calculations, the only leftover force would push the boat forward—and at high speeds. After a series of incremental improvements followed by incrementally larger crashes, Vestas, the Danish wind turbine manufacturer, stepped in with enough sponsorship money to allow for a more thorough analysis. Even without the SailRocket’s success, the shape of wind-powered vehicles is moving away from the classic billowing sails.

Topics: Design , Hydrofoil , Water , Wind , Boats , Keel
Commentary by Dr. Valentin Fuster
Mechanical Engineering. 2013;135(08):66-71. doi:10.1115/1.2013-AUG-4.
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This article focuses on studying blade tip clearance phenomena. It is important to realize that to be freely turning, a blade (or a cantilevered stator) must have a clearance gap between its tip and the engine casing (or hub). Such clearances introduce aerodynamic losses, decreasing gas turbine efficiency. Tip leakage losses in compressors can be significant and have been reviewed by the experts. During transient operations, gas turbine blade tip clearances will change based on blade/disk centrifugal loads and the different response times of engine parts to thermally induced expansions and contractions. Designers have perfected active clearance control (ACC) systems to deal with these transient conditions. ACC uses cool or hot gas path and fan air at appropriate times during transients to control the rate of expansion or contraction of internal parts adjacent to the gas path and outer casings. The research shows that continued enhancement of blade tip clearance management systems over a range of engine operating conditions has brought and will bring about gains in gas turbine efficiency.

Commentary by Dr. Valentin Fuster
Mechanical Engineering. 2013;135(08):67-70. doi:10.1115/1.2013-AUG-5.
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This article is a memoir of Harry Schmidt, a Pratt & Whitney test pilot at Edwards AFB during the mid-1950s. Schmidt recalls that the J57 was critical to P&W’s long-term success, so the testing program was vital both to the United States Air Force (USAF) as well as to P&W. Early in the testing program, the engine would stall even in a shallow bank; however, after a couple of months, the team was able to complete hard turns without a stall. To solve the high-speed stall problem, P&W engineers tweaked the engine turbine vanes to provide greater stall margin. In the fall of 1955, the team received its F-101, a twin-engine fighter with two J57s and a top speed of about Mach 1.5. Because the team was operating the fastest aircraft in the world, they figured they could also set an unofficial world’s altitude record by achieving max Mach at about 40,000’ and then climb trading airspeed for altitude.

Commentary by Dr. Valentin Fuster

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