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Topic Review
Postcrossing
Postcrossing is an online project that allows its members to send and receive postcards from all over the world. The project's tag line is "send a postcard and receive a postcard back from a random person somewhere in the world!” Its members, also known as postcrossers, send postcards to other members and receive postcards back from other random postcrossers. Where the postcards come from is always a surprise. Postcrossing is the union of the words "postcard" and "crossing" and its origin "is loosely based on the Bookcrossing site". However, the "crossing" or exchange of postcards works in a different way. A member sends a postcard to another postcrosser and receives a postcard back from a random postcrosser. Exchanges between the same two members only occur once; although direct swaps between members happen, they are not part of the official happenings on the site. The project is completely free and anyone with an address can create an account. The postcards and postage fees to mail them are the responsibility of each user. By February 2018 Postcrossing had more than 719,000 members in 212 countries who had registered and exchanged over 45 million postcards that traveled over 229 billion kilometers. The highest concentration of Postcrossing members reside (in order) in Russia, Taiwan, China, the United States, Germany, the Netherlands, Poland, Belarus, Ukraine, Finland and the Czech Republic, each with over 20,000 members. Globally, most postcrossers reside in North America, Europe and East Asia. Of particular note, Postcrossing is popular in eastern European and former-Soviet states. As of January 2012, more than a quarter of the combined total of postcards were sent from Finland, Russia, Estonia, Latvia, Lithuania, Belarus and Ukraine.
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Topic Review
List of Gliders (T)
This is a list of gliders/sailplanes of the world, (this reference lists all gliders with references, where available) Note: Any aircraft can glide for a short time, but gliders are designed to glide for longer.
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Topic Review
Measurement and Signature Intelligence
Measurement and signature intelligence (MASINT) is a technical branch of intelligence gathering, which serves to detect, track, identify or describe the distinctive characteristics (signatures) of fixed or dynamic target sources. This often includes radar intelligence, acoustic intelligence, nuclear intelligence, and chemical and biological intelligence. MASINT is defined as scientific and technical intelligence derived from the analysis of data obtained from sensing instruments for the purpose of identifying any distinctive features associated with the source, emitter or sender, to facilitate the latter's measurement and identification. MASINT specialists themselves struggle with providing simple explanations of their field. One attempt calls it the “CSI” of the intelligence community, in imitation of the television series CSI: Crime Scene Investigation. This emphasizes how MASINT depends on a great many sciences to interpret data. Another possible definition calls it "astronomy except for the direction of view." The allusion here is to observational astronomy being a set of techniques that do remote sensing looking away from the earth (contrasted with how MASINT employs remote sensing looking toward the earth). Astronomers make observations in multiple electromagnetic spectra, ranging through radio waves, infrared, visible, and ultraviolet light, into the X-ray spectrum and beyond. They correlate these multispectral observations and create hybrid, often “false-color” images to give a visual representation of wavelength and energy, but much of their detailed information is more likely a graph of such things as intensity and wavelength versus viewing angle.
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Topic Review
List of Most Successful U-boat Commanders
The list of most successful U-boat commanders contains the top-scoring German U-boat commanders in the two World Wars based on their total tonnage sunk. The tonnage figures (and sometimes the number of ships sunk) is still being debated among historians. This is often due to convoy battles at night when an attacking "wolfpack" fired torpedoes into the convoy and two (sometimes more) commanders claimed the same ship. Although post-war research has clarified most of those claims, some are still in question.
  • 4.0K
  • 04 Nov 2022
Topic Review
Gee Bee Model Z
The Granville Gee Bee Model Z was an United States racing aircraft of the 1930s, the first of the Super Sportster aircraft built by Granville Brothers Aircraft of Springfield, Massachusetts, with the sole intent of winning the Thompson Trophy, which it did in 1931. However, it soon suffered a fatal crash during a world speed record attempt, starting the reputation of the Gee Bee aircraft as killers.
  • 453
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Topic Review
Tracking and Data Relay Satellite
File:TDRS Heart of Communication.ogv File:Tracking Data Relay Satellite (TDRS) Orbital Fleet Communicating with User Spacecraft.ogg File:Tracking Data Relay Satellite (TDRS) Orbital Fleet Communicating with User Spacecraft 2017 - 360 video.webm A tracking and data relay satellite (TDRS) is a type of communications satellite that forms part of the Tracking and Data Relay Satellite System (TDRSS) used by NASA and other United States government agencies for communications to and from independent "User Platforms" such as satellites, balloons, aircraft, the International Space Station, and remote bases like the Amundsen-Scott South Pole Station. This system was designed to replace an existing worldwide network of ground stations that had supported all of NASA's crewed flight missions and uncrewed satellites in low-Earth orbits. The primary system design goal was to increase the amount of time that these spacecraft were in communication with the ground and improve the amount of data that could be transferred. These TDRSS satellites are all designed and built to be launched to and function in geosynchronous orbit, 35,786 km (22,236 mi) above the surface of the Earth. The first seven TDRSS satellites were built by the TRW corporation. The three later versions have been manufactured by the Boeing corporation's Satellite Systems division. Thirteen satellites have been launched; however, one was destroyed in the Challenger disaster. TDRS-1 was decommissioned in October 2009. TDRS-4 was decommissioned in December 2011. Ten TDRSS satellites are currently in service. All of the TDRSS satellites have been managed by NASA's Goddard Space Flight Center. The contract for TDRS versions L & K was awarded to Boeing on December 20, 2007. On November 30, 2011, NASA announced the decision to order an additional third-generation TDRS satellite, TDRS M.
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Topic Review
SSC Aero
The SSC Ultimate Aero is a mid-engined sports car that was produced by SSC North America (formerly known as Shelby SuperCars) from 2004 until 2013. The SSC Ultimate Aero held the world production car speed record title, according to the Guinness World Records, from 2007 (when it was officially timed at 410 km/h) until the introduction of the Bugatti Veyron Super Sport in 2010. In April 2013, the Guinness World Records temporarily disqualified the Veyron's record time for a period of five days due to concerns about electronic speed limiting changing the function of the car, but after investigation reinstated the Veyron as the record holder. The SSC Ultimate Aero was not sold with electronic driver aids such as an anti-lock braking system or traction control system, as according to Jerod Shelby (no relations to Carroll Shelby), "Early design philosophy on the car was to make it a driver's car. I wanted a car that you not only throttled with your right foot but at times you could steer with your right foot and a sensor."
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  • 04 Nov 2022
Topic Review
Diamond DA40
The Diamond DA40 Star is an Austrian four-seat, single-engine, light aircraft constructed from composite materials. Built in both Austria and Canada, it was developed as a four-seat version of the earlier DA20 by Diamond Aircraft Industries.
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  • 04 Nov 2022
Topic Review
Electrical Contacts
An electrical contact is an electrical circuit component found in electrical switches, relays, connectors and circuit breakers. Each contact is a piece of electrically conductive material, typically metal. When a pair of contacts touch, they can pass an electrical current with a certain contact resistance, dependent on surface structure, surface chemistry and contact time; when the pair is separated by an insulating gap, then the pair does not pass a current. When the contacts touch, the switch is closed; when the contacts are separated, the switch is open. The gap must be an insulating medium, such as air, vacuum, oil, SF6. Contacts may be operated by humans in push-buttons and switches, by mechanical pressure in sensors or machine cams, and electromechanically in relays. The surfaces where contacts touch are usually composed of metals such as silver or gold alloys that have high electrical conductivity, wear resistance, oxidation resistance and other properties.
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Topic Review
Mercedes-Benz CLS-Class (W219)
The C219 Mercedes-Benz CLS-Class is the first generation of the CLS-Class range of four-door coupe features a fastback body style by Mercedes-Benz, and was produced between 2004 and 2010. The CLS-Class has only four seats and is marketed by Mercedes as a four-door coupé. For this reason, in Germany and in whole Europe the model code name is C219 while in US the CLS is more commonly named as W219 model. It was the first model globally to introduce this four-door coupe style and VW followed with the Volkswagen CC model in 2008. The car is less practical than the W211 E-Class that it is based on, with less legroom, headroom, and boot space. The CLS-Class is priced above the E-Class, but below the S-Class in the Mercedes model range. It was replaced by the Mercedes-Benz CLS-Class (W218) in 2011.
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