Metallurgical Design and Development of NASA Crawler/Transporter Tread Belt Shoe Castings

The NASA Crawler/Transporters (CT-1 and CT-2) used to transport the Space Shuffles are one of the largest tracked vehicles in existence today. Two of these machines have been used to move space flight vehicles at Kennedy Space Center since the Apollo missions of the 1960's and relatively few modifications have been made to keep them operational. In September of 2003 during normal Crawler/Transporter operations cracks were observed along the roller pad surfaces of several tread belt shoes. Further examination showed 20 cracked shoes on CT-1 and 40 cracked shoes on CT-2 and a formal failure analysis investigation was undertaken while the cracked shoes were replaced. Six shoes were cross-sectioned with the fracture surfaces exposed and it was determined that the cracks were due to fatigue that initiated on the internal casting web channels at pre-existing casting defects and propagated through thickness both transgranularly and intergranularly between internal shrinkage cavities, porosity, and along austenitic and ferritic grain boundaries. The original shoes were cast during the 1960's using a modified 861330 steel with slightly higher levels of chromium, nickel and molybdenum followed by heat treatment to achieve a minimum tensile strength of 11 Oksi. Subsequent metallurgical analysis of the tread belt shoes after multiple failures showed excessive internal defects, alloy segregation, a nonuniform ferritic/ bainitic/martensitic microstructure, and low average tensile properties indicative of poor casting and poor heat-treatment. As a result, NASA funded an initiative to replace all of the tread belt shoes on both crawler/transporters along with a redesign of the alloy, manufacturing, and heat-treatment to create a homogeneous cast structure with uniform mechanical and metallurgical properties. ME Global, a wholly owned subsidiary of ME Elecmetal based in Minneapolis, MN was selected as manufacturing and design partner to develop the new shoes and this paper describes the research, development, and manufacturing that resulted in the successful delivery of 1044 new Crawler/Transporter tread belt shoes all meeting rigid metallurgical and mechanical design criteria derived from finite element modeling of the stress loads required for safe space shuttle transport

Ridazz, Wrenches, and Wonks: A Revolution on Two Wheels Rolls Into Los Angeles

How can we make cities more livable? Los Angeles, in particular, is a notably challenging place to live. For many, it is hard to see Los Angeles—city or county—as anything other than a huge, sprawling, and some would say placeless place. Los Angeles is known by many as the place that tore up more than 1,000 miles of streetcar lines to make way for millions of cars and hundreds of miles of freeways. Because of this, Los Angeles is also known for its poor air quality and jammed freeways. Those who live in Los Angeles know that it can be a very real challenge to get around. But Los Angeles is also a city of possibilities. It is one of the most culturally diverse cities in the world. It is mostly flat. It seldom rains. Surprisingly, Los Angeles has an alternative bike culture that has emerged and rapidly matured over the last nineteen years. It has gone from a rowdy and radical culture of bike messengers gathering for night rides to a substantial and growing community of riders, do-it-yourself bike mechanics, and homegrown transportation activists and advocates who have influenced the way bikes and riders are perceived and even how regional transportation policy is developed and implemented. How and why has that come to pass? In answering these questions, this dissertation seeks to describe the recent history of bike culture in Los Angeles through the eyes of its originators and ongoing participants. This is a narrative account of the recent past and the present in Los Angeles, California, in which a collection of bicycle-related phenomena appear to be transforming the land in ways that many might agree constitute a form of revitalization. The electronic version of this Dissertation is at Ohiolink ETDCenter, http://etd.ohiolink.edu and AURA, http://aura.antioch.edu/. An MP4 video introduction by the author accompanies this document

Pioneering in the Upper Big Sioux Valley : Medary, Sioux Falls, Dell Rapids, Flandreau, Brookings, Watertown

https://openprairie.sdstate.edu/archives_rare-books/1022/thumbnail.jp

Lac qui Parle, Its Missionaries, Traders and Indians

https://openprairie.sdstate.edu/archives_rare-books/1025/thumbnail.jp

An investigation into brake release on the catapult : a non-ergonomic solution to an ergonomic problem in the T-45 Goshawk

This study investigates a modification to the T-45 Goshawk that releases brake pressure when the aircraft is on the catapult of an aircraft carrier, preventing the pilot\u27s inadvertent brake application in the cockpit from applying the brakes at the wheel. The modification arose from numerous incidents of Student Naval Aviators inadvertently actuating the brakes during catapult shots, ultimately causing the tire(s) to explode. The subsequent landings with blown tires have proven extremely hazardous resulting in at least three catastrophic mishaps in four years of operational training. The modification takes a radical departure from conventional naval aviation wisdom concerning the pilot\u27s control of brakes, because it inhibits hydraulic pressure from actuating the brakes. This system effectively removes the pilot\u27s pedal input to the brake system during a catapult launch, when brake application is undesirable. The problem of inadvertent braking on the catapult results mainly from cockpit ergonomics in the T-45. Specifically, the fulcrum of the brake pedal sits too close to the floor beneath, preventing the pilot from executing normal catapult procedures conducted in the fleet, where he slides his feet to the deck for the catapult launch. The alternative solutions included a Toe-bar and minor adjustments to the brake pedal height and deck plate location within the limits of the aircraft\u27s major structure. The Toe-bar was a reference point at the mid-point of the brake pedal, under which the pilot placed the toe of his boot. It effectively placed the pilot in a position that prevented him from applying sufficient moment to actuate the brakes. The Toe-bar was implemented in fleet T-45 aircraft, and produced moderate success at preventing blown tires on the catapult. It has ergonomic issues of its own however, since it places the pilot in an extremely uncomfortable position that is potentially hazardous in an ejection scenario. The other modifications were found unsuitable, particularly for larger pilots during early cockpit mock-up testing. This study provides an analysis of the causes of blown tires on the catapult, the human factors involved with alternative ergonomic solutions, the method of testing the brake release solution, and a psychological discussion of the transfer of training concerns regarding students transitioning to fleet aircraft after flying the T-45 with brake release incorporated. The author concluded that the brake release system will successfully prevent pilot brake application from resulting in blown tires on the catapult, but discovered one correctable ground handling deficiency with the prototype system as it was installed in the T-45. The author made three recommendations: • The Navy should incorporate the brake release system in the T-45 after correcting the ground handling deficiency. • The Navy should incorporate the brake release system in future fleet aircraft • The Navy should research whether the blown tire problem exists in fleet aircraft, and pending the results modify existing fleet aircraft with the brake release system

Composite powder particles

A liquid coating composition including a coating vehicle and composite powder particles disposed within the coating vehicle. Each composite powder particle may include a magnesium component, a zinc component, and an indium component

Polymorphism of Eimerian Oocysts: A Dilemma Posed by Working with Some Naturally Infected Hosts

Morphological variation of sporulated oocysts within individual eimerian species is well documented (Joyner, 1982. In Biology of the Coccidia, P. L. Long (ed.). University Park Press, Baltimore, pp. 35-62). In some cases, oocysts of a single eimerian species are known to vary in size by as much as 40% during patency (Duszynski, 1971, Journal of Parasitology 57: 948-952). During a survey to determine the prevalence of coccidiosis in sandhill cranes (Grus canadensis) wintering in New Mexico (Parker and Duszynski, 1986, Journal of Wildlife Diseases 21: 25-35), marked polymorphism was observed among sporulated oocysts of Eimeria reichenowi. Oocysts were obtained from intestinal contents of cranes necropsied in the field and processed for study by routine sporulation and flotation techniques (Duszynski et al., 1982, Journal of Parasitology 68: 1,146-1,148). Initially, oocysts were categorized into 5 groups based on obvious qualitative/quantitative features including oocyst wall texture, appearance of the sporocyst residuum, and the number of polar bodies. Fifty-seven of 118 (48%) fecal samples with E. reichenowi contained 2 or more morphological types of oocysts. Oocysts were measured under oil immersion (100 x Neofluar objective, Zeiss Universal Photomicroscope) and differences between the 5 oocyst groups were tested for significance (P \u3c0.05) using the Student-Newman-Keuls procedure

Anti-Corrosive Powder Particles

The National Aeronautics and Space Administration (NASA) seeks partners for a new approach in protecting embedded steel surfaces from corrosion. Corrosion of reinforced steel in concrete structures is a significant problem for NASA structures at Kennedy Space Center (KSC) because of the close proximity of the structures to salt spray from the nearby Atlantic Ocean. In an effort to minimize the damage to such structures, coatings were developed that could be applied as liquids to the external surfaces of a substrate in which the metal structures were embedded. The Metallic Pigment Powder Particle technology was developed by NASA at KSC. This technology combines the metallic materials into a uniform particle. The resultant powder can be sprayed simultaneously with a liquid binder onto the surface of concrete structures with a uniform distribution of the metallic pigment for optimum cathodic protection of the underlying steel in the concrete. Metallic Pigment Powder Particle technology improves upon the performance of an earlier NASA technology Liquid Galvanic Coating (U.S. Patent No. 6,627,065)