The Antarctic Snow Cruiser was a vehicle designed from 1937 to 1939 under the direction of Thomas Poulter, intended to facilitate transport in Antarctica during the United States Antarctic Service Expedition (1939–41). The Snow Cruiser was also known as "The Penguin," "Penguin 1" or "Turtle" in some published material.
Poulter had been second in command of Byrd's Second Antarctic Expedition, launched in 1934. From his time in the Antarctic, Poulter had devised several innovative features. However, the massive Snow Cruiser generally failed to operate as hoped under the difficult conditions, and was eventually abandoned in Antarctica. Rediscovered under a deep layer of snow in 1958, it later disappeared again due to shifting ice conditions.
- "Antarctic Snow Cruiser" | 2020-03-09 | 89 Upvotes 52 Comments
Frederick Benjamin "Ben" Carlin (27 July 1912 – 7 March 1981) was an Australian adventurer who was the first person to circumnavigate the world in an amphibious vehicle. Born in Northam, Western Australia, Carlin attended Guildford Grammar School in Perth, and later studied mining engineering at the Kalgoorlie School of Mines. After qualifying as an engineer, he worked on the Goldfields before in 1939 emigrating to China to work in a British coal mine. In the Second World War, Carlin was posted to the Indian Army Corps of Engineers, serving in India, Italy, and throughout the Middle East. After his discharge from service in 1946, he emigrated to the United States with his American wife, Elinore (née Arone).
Sparked by an idea he had had whilst in the military, Carlin proposed that the couple honeymoon by crossing the Atlantic Ocean in a modified Ford GPA (an amphibious version of the Ford GPW Jeep), which they named the Half-Safe. Beginning their trip in Montreal, Quebec, Canada, the Carlins finally completed the transatlantic crossing in 1951, after unsuccessful attempts. From there, they travelled to Europe, temporarily settling in Birmingham to raise more money. They resumed their journey in 1954, travelling overland through the Middle East before arriving in Calcutta. After a short fundraising trip to Australia, Carlin's wife left to return to the United States. He resumed the journey with new partners, travelling through South-East Asia and the Far East to the northern tip of Japan, and then to Alaska. After an extended tour through the United States and Canada, he and Half-Safe finally returned to Montreal, having travelled over 17,000 kilometres (11,000 mi) by sea and 62,000 kilometres (39,000 mi) by land during a ten-year journey. Following Carlin's death in 1981, Half-Safe was acquired by Guildford Grammar, his old school, where it remains on display.
- "Ben Carlin" | 2020-01-04 | 125 Upvotes 7 Comments
Dagen H (H day), today usually called "Högertrafikomläggningen" ("The right-hand traffic diversion"), was the day on 3 September 1967, in which the traffic in Sweden switched from driving on the left-hand side of the road to the right. The "H" stands for "Högertrafik", the Swedish word for "right traffic". It was by far the largest logistical event in Sweden's history.
- "Dagen H – the day Sweden switched to driving on the right" | 2013-05-17 | 13 Upvotes 1 Comments
- "Dagen H: The day Sweden switched to the right hand side of the road" | 2010-07-19 | 50 Upvotes 19 Comments
A Hyperloop is a proposed mode of passenger and freight transportation, first used to describe an open-source vactrain design released by a joint team from Tesla and SpaceX. Hyperloop is a sealed tube or system of tubes through which a pod may travel free of air resistance or friction conveying people or objects at high speed while being very efficient, thereby drastically reducing travel times over medium-range distances.
Elon Musk's version of the concept, first publicly mentioned in 2012, incorporates reduced-pressure tubes in which pressurized capsules ride on air bearings driven by linear induction motors and axial compressors.
The Hyperloop Alpha concept was first published in August 2013, proposing and examining a route running from the Los Angeles region to the San Francisco Bay Area, roughly following the Interstate 5 corridor. The Hyperloop Genesis paper conceived of a hyperloop system that would propel passengers along the 350-mile (560 km) route at a speed of 760 mph (1,200 km/h), allowing for a travel time of 35 minutes, which is considerably faster than current rail or air travel times. Preliminary cost estimates for this LA–SF suggested route were included in the white paper—US$6 billion for a passenger-only version, and US$7.5 billion for a somewhat larger-diameter version transporting passengers and vehicles—although transportation analysts had doubts that the system could be constructed on that budget; some analysts claimed that the Hyperloop would be several billion dollars overbudget, taking into consideration construction, development, and operation costs.
The Hyperloop concept has been explicitly "open-sourced" by Musk and SpaceX, and others have been encouraged to take the ideas and further develop them. To that end, a few companies have been formed, and several interdisciplinary student-led teams are working to advance the technology. SpaceX built an approximately 1-mile-long (1.6 km) subscale track for its pod design competition at its headquarters in Hawthorne, California.
- "Hyperloop" | 2013-06-01 | 10 Upvotes 9 Comments
Fifty-eight selected navigational stars are given a special status in the field of celestial navigation. Of the approximately 6,000 stars visible to the naked eye under optimal conditions, the selected stars are among the brightest and span 38 constellations of the celestial sphere from the declination of −70° to +89°. Many of the selected stars were named in antiquity by the Babylonians, Greeks, Romans, and Arabs.
The star Polaris, often called the "North Star", is treated specially due to its proximity to the north celestial pole. When navigating in the Northern Hemisphere, special techniques can be used with Polaris to determine latitude or gyrocompass error. The other 57 selected stars have daily positions given in nautical almanacs, aiding the navigator in efficiently performing observations on them. A second group of 115 "tabulated stars" can also be used for celestial navigation, but are often less familiar to the navigator and require extra calculations.
For purposes of identification, the positions of navigational stars — expressed as declination and sidereal hour angle — are often rounded to the nearest degree. In addition to tables, star charts provide an aid to the navigator in identifying the navigational stars, showing constellations, relative positions, and brightness.
- "List of selected stars for navigation" | 2019-09-24 | 76 Upvotes 13 Comments
A manhole cover or maintenance hole cover is a removable plate forming the lid over the opening of a manhole, an opening large enough for a person to pass through that is used as an access point for an underground vault or pipe. It is designed to prevent anyone or anything from falling in, and to keep out unauthorized persons and material.
Manhole covers date back at least to the era of ancient Rome, which had sewer grates made from stone.
- "Manhole cover thought to be propelled into space" | 2013-11-01 | 21 Upvotes 9 Comments
Peak car (also peak car use or peak travel) is a hypothesis that motor vehicle distance traveled per capita, predominantly by private car, has peaked and will now fall in a sustained manner. The theory was developed as an alternative to the prevailing market saturation model, which suggested that car use would saturate and then remain reasonably constant, or to GDP-based theories which predict that traffic will increase again as the economy improves, linking recent traffic reductions to the Great Recession of 2008.
The theory was proposed following reductions, which have now been observed in Australia, Belgium, France, Germany, Iceland, Japan (early 1990s), New Zealand, Sweden, the United Kingdom (many cities from about 1994) and the United States. A study by Volpe Transportation in 2013 noted that average miles driven by individuals in the United States has been declining from 900 miles (1,400 km) per month in 2004 to 820 miles (1,320 km) in July 2012, and that the decline had continued since the recent upturn in the US economy.
A number of academics have written in support of the theory, including Phil Goodwin, formerly Director of the transport research groups at Oxford University and UCL, and David Metz, a former Chief Scientist of the UK Department of Transport. The theory is disputed by the UK Department for Transport, which predicts that road traffic in the United Kingdom will grow by 50% by 2036, and Professor Stephen Glaister, Director of the RAC Foundation, who say traffic will start increasing again as the economy improves. Unlike peak oil, a theory based on a reduction in the ability to extract oil due to resource depletion, peak car is attributed to more complex and less understood causes.
- "Peak car" | 2015-05-03 | 210 Upvotes 134 Comments
Pykrete is a frozen ice alloy , originally made of approximately 14 percent sawdust or some other form of wood pulp (such as paper) and 86 percent ice by weight (6 to 1 by weight). During World War II, Geoffrey Pyke proposed it as a candidate material for a supersized aircraft carrier for the British Royal Navy. Pykrete features unusual properties, including a relatively slow melting rate due to its low thermal conductivity, as well as a vastly improved strength and toughness compared to ordinary ice. These physical properties can make the material comparable to concrete, as long as the material is kept frozen.
Pykrete is slightly more difficult to form than concrete, as it expands during the freezing process. However, it can be repaired and maintained using seawater as a raw material. The mixture can be moulded into any shape and frozen, and it will be tough and durable, as long as it is kept at or below freezing temperature. Resistance to gradual creep or sagging is improved by lowering the temperature further, to −15 °C (5 °F).
- "Pykrete" | 2015-07-07 | 114 Upvotes 41 Comments
SkySails GmbH & Co. KG is a Hamburg-based company that sells kite rigs to propel cargo ships, large yachts and fishing vessels by wind energy. Ships are pulled by an automatically-controlled foil kite of some hundreds of square meters. For multiple reasons, they give many times the thrust per unit area of conventional mast-mounted sails.
The systems save fuel, and reduce carbon emissions and shipping costs, but have not been widely adopted.
- "SkySails" | 2019-07-04 | 126 Upvotes 42 Comments
Smeed's Law, named after R. J. Smeed, who first proposed the relationship in 1949, is a purported empirical rule relating traffic fatalities to traffic congestion as measured by the proxy of motor vehicle registrations and country population. The law proposes that increasing traffic volume (an increase in motor vehicle registrations) leads to an increase in fatalities per capita, but a decrease in fatalities per vehicle.
Smeed also predicted that the average speed of traffic in central London would always be nine miles per hour, because that is the minimum speed that people tolerate. He predicted that any intervention intended to speed traffic would only lead to more people driving at this "tolerable" speed unless there were any other disincentives against doing so.
His hypothesis in relation to road traffic safety has been refuted by several authors, who point out that fatalities per person have decreased in many countries, when the "Law" requires that they should increase as long as the number of vehicles per person continues to rise.
- "Smeed's law" | 2009-05-08 | 33 Upvotes 5 Comments