Air Force One
Air Force One is the official air traffic control call sign for a United States Air Force aircraft carrying the President of the United States. In common parlance the term describes those U. S. Air Force aircraft designed and used to transport the president; the presidential aircraft is a prominent symbol of its power. The idea of designating specific military aircraft to transport the President arose in 1943, when officials of the United States Army Air Forces, the predecessor to the U. S. Air Force, became concerned over the reliance on commercial airlines to transport the president. A C-87 Liberator Express was reconfigured for use as the first dedicated VIP and presidential transport aircraft and named Guess Where II, but the Secret Service rejected it because of its safety record. A C-54 Skymaster was converted for presidential use; the "Air Force One" call sign was created after a 1953 incident during which a Lockheed Constellation named Columbine II, carrying President Dwight D. Eisenhower, entered the same airspace as a commercial airline flight using the same flight number.
A number of aircraft types have been used as Air Force One since the creation of the presidential fleet, starting with two Lockheed Constellations in the late 1950s: Columbine II and Columbine III. It operated two Boeing 707s, introduced in the 1960s and 1970s; the U. S. Air Force plans to procure the Boeing 747-8 for the next version of Air Force One. On 11 October 1910, Theodore Roosevelt became the first U. S. president to fly in an aircraft, an early Wright Flyer from Kinloch Field near St. Louis, Missouri, he was no longer in office at the time. The record-making occasion was a brief overflight of the crowd at a county fair but was nonetheless the beginning of presidential air travel. Prior to World War II, overseas and cross-country presidential travel was rare; the lack of wireless telecommunication and available modes of transportation made long-distance travel impractical, as it took too much time and isolated the president from events in Washington, D. C. Railroads were a more reliable option if the president needed to travel to distant states.
By the late 1930s, with the arrival of aircraft such as the Douglas DC-3, increasing numbers of the U. S. public saw passenger air travel as a reasonable mode of transportation. All-metal aircraft, more reliable engines, new radio aids to navigation had made commercial airline travel safer and more convenient. Life insurance companies began to offer airline pilots insurance policies, albeit at extravagant rates, many commercial travelers and government officials began using the airlines in preference to rail travel for longer trips. Franklin D. Roosevelt was the first president to fly in an aircraft while in office; the first aircraft obtained for presidential travel was a Douglas Dolphin amphibian delivered in 1933, designated RD-2 by the US Navy and based at the Naval base at Anacostia D. C; the Dolphin was modified with luxury upholstery for four passengers and a small separate sleeping compartment. The aircraft remained in service as a presidential transport from 1933 until 1939. There are no reports, however, on whether the president flew in the aircraft.
During World War II, Roosevelt traveled on the Dixie Clipper, a Pan Am-crewed Boeing 314 flying boat to the 1943 Casablanca Conference in Morocco, a flight that covered 5,500 miles in three legs. The threat from the German submarines throughout the Battle of the Atlantic made air travel the preferred method of VIP transatlantic transportation. Concerned about relying upon commercial airlines to transport the president, USAAF leaders ordered the conversion of a military aircraft to accommodate the special needs of the Commander-in-Chief; the first dedicated aircraft proposed for presidential use was a C-87A VIP transport aircraft. This aircraft, number 41-24159, was modified in 1943 for use as a presidential VIP transport, the Guess Where II, intended to carry President Franklin D. Roosevelt on international trips. Had it been accepted, it would have been the first aircraft to be used in presidential service. However, after a review of the C-87's controversial safety record in service, the Secret Service flatly refused to approve the Guess Where II for presidential carriage.
As the C-87 was a derivative of the Consolidated B-24 Liberator bomber, it presented strong offensive impressions to enemy fighter aircraft as well as foreign destinations visited, an issue not present with airplanes that were used purely for transport. The Guess Where II was used to transport senior members of the Roosevelt administration on various trips. In March 1944, it transported Eleanor Roosevelt on a goodwill tour of several Latin American countries; the C-87 was scrapped in 1945. The Secret Service subsequently reconfigured a Douglas C-54 Skymaster for presidential transport duty; the VC-54C aircraft, nicknamed the Sacred Cow, included a sleeping area, radio telephone, retractable elevator to lift Roosevelt in his wheelchair. As modified, the VC-54C was used by President Roosevelt only once before his death, on his trip to the Yalta Conference in February 1945. Sacred Cow is now on display at the National Museum of the United States Air Force at Wright-Patterson AFB, Ohio. After Roosevelt's death in April 1945, Vice President Harry S. Truman became president.
The legislation that created the U. S. Air Force, the Nati
Concrete Portland cement concrete, is a composite material composed of fine and coarse aggregate bonded together with a fluid cement that hardens over time—most a lime-based cement binder, such as Portland cement, but sometimes with other hydraulic cements, such as a calcium aluminate cement. It is distinguished from other, non-cementitious types of concrete all binding some form of aggregate together, including asphalt concrete with a bitumen binder, used for road surfaces, polymer concretes that use polymers as a binder; when aggregate is mixed together with dry Portland cement and water, the mixture forms a fluid slurry, poured and molded into shape. The cement reacts chemically with the water and other ingredients to form a hard matrix that binds the materials together into a durable stone-like material that has many uses. Additives are included in the mixture to improve the physical properties of the wet mix or the finished material. Most concrete is poured with reinforcing materials embedded to provide tensile strength, yielding reinforced concrete.
Famous concrete structures include the Panama Canal and the Roman Pantheon. The earliest large-scale users of concrete technology were the ancient Romans, concrete was used in the Roman Empire; the Colosseum in Rome was built of concrete, the concrete dome of the Pantheon is the world's largest unreinforced concrete dome. Today, large concrete structures are made with reinforced concrete. After the Roman Empire collapsed, use of concrete became rare until the technology was redeveloped in the mid-18th century. Worldwide, concrete has overtaken steel in tonnage of material used; the word concrete comes from the Latin word "concretus", the perfect passive participle of "concrescere", from "con-" and "crescere". Small-scale production of concrete-like materials was pioneered by the Nabatean traders who occupied and controlled a series of oases and developed a small empire in the regions of southern Syria and northern Jordan from the 4th century BC, they discovered the advantages of hydraulic lime, with some self-cementing properties, by 700 BC.
They built kilns to supply mortar for the construction of rubble-wall houses, concrete floors, underground waterproof cisterns. They kept the cisterns secret; some of these structures survive to this day. In the Ancient Egyptian and Roman eras, builders discovered that adding volcanic ash to the mix allowed it to set underwater. German archaeologist Heinrich Schliemann found concrete floors, which were made of lime and pebbles, in the royal palace of Tiryns, which dates to 1400–1200 BC. Lime mortars were used in Greece and Cyprus in 800 BC; the Assyrian Jerwan Aqueduct made use of waterproof concrete. Concrete was used for construction in many ancient structures; the Romans used concrete extensively from 300 BC to a span of more than seven hundred years. During the Roman Empire, Roman concrete was made from quicklime, pozzolana and an aggregate of pumice, its widespread use in many Roman structures, a key event in the history of architecture termed the Roman Architectural Revolution, freed Roman construction from the restrictions of stone and brick materials.
It enabled revolutionary new designs in terms of both structural dimension. Concrete, as the Romans knew it, was a revolutionary material. Laid in the shape of arches and domes, it hardened into a rigid mass, free from many of the internal thrusts and strains that troubled the builders of similar structures in stone or brick. Modern tests show that opus caementicium had as much compressive strength as modern Portland-cement concrete. However, due to the absence of reinforcement, its tensile strength was far lower than modern reinforced concrete, its mode of application was different: Modern structural concrete differs from Roman concrete in two important details. First, its mix consistency is fluid and homogeneous, allowing it to be poured into forms rather than requiring hand-layering together with the placement of aggregate, which, in Roman practice consisted of rubble. Second, integral reinforcing steel gives modern concrete assemblies great strength in tension, whereas Roman concrete could depend only upon the strength of the concrete bonding to resist tension.
The long-term durability of Roman concrete structures has been found to be due to its use of pyroclastic rock and ash, whereby crystallization of strätlingite and the coalescence of calcium–aluminum-silicate–hydrate cementing binder helped give the concrete a greater degree of fracture resistance in seismically active environments. Roman concrete is more resistant to erosion by seawater than modern concrete; the widespread use of concrete in many Roman structures ensured that many survive to the present day. The Baths of Caracalla in Rome are just one example. Many Roman aqueducts and bridges, such as the magnificent Pont du Gard in southern France, have masonry cladding on a concrete core, as does the dome of the Pantheon. After the Roman Empire, the use of burned lime and pozzolana was reduced until the technique was all but forgotten between 500 and the 14th century. From the 14th century to the mid-18th century, the use of cement returned; the Canal du Midi was built using concrete in 1670.
The greatest step forward in the modern use
The Cattle Bank is a historic bank building located at 102 E. University Ave. in Champaign, Illinois. Built in 1856, it is the oldest commercial building in Champaign, it opened as a branch of Urbana's first bank. Champaign was the southern terminus of a railroad line to Chicago, so cattle raisers from the surrounding area drove their cattle to Champaign to ship them to the Chicago market; the Cattle Bank provided loan services to these cattlemen. The building was added to the National Register of Historic Places on August 19, 1975, it is home to the Champaign County Historical Museum. Champaign County Historical Museum
According to the International Civil Aviation Organization, a runway is a "defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft". Runways may be a natural surface. In January 1919, aviation pioneer Orville Wright underlined the need for "distinctly marked and prepared landing places, the preparing of the surface of reasonably flat ground an expensive undertaking there would be a continuous expense for the upkeep." Runways are named by a number between 01 and 36, the magnetic azimuth of the runway's heading in decadegrees. This heading differs from true north by the local magnetic declination. A runway numbered 09 points east, runway 18 is south, runway 27 points west and runway 36 points to the north; when taking off from or landing on runway 09, a plane is heading around 90°. A runway can be used in both directions, is named for each direction separately: e.g. "runway 15" in one direction is "runway 33" when used in the other. The two numbers differ by 18.
For clarity in radio communications, each digit in the runway name is pronounced individually: runway one-five, runway three-three, etc.. A leading zero, for example in "runway zero-six" or "runway zero-one-left", is included for all ICAO and some U. S. military airports. However, most U. S. civil aviation airports drop the leading zero. This includes some military airfields such as Cairns Army Airfield; this American anomaly may lead to inconsistencies in conversations between American pilots and controllers in other countries. It is common in a country such as Canada for a controller to clear an incoming American aircraft to, for example, runway 04, the pilot read back the clearance as runway 4. In flight simulation programs those of American origin might apply U. S. usage to airports around the world. For example, runway 05 at Halifax will appear on the program as the single digit 5 rather than 05. If there is more than one runway pointing in the same direction, each runway is identified by appending left and right to the number to identify its position — for example, runways one-five-left, one-five-center, one-five-right.
Runway zero-three-left becomes runway two-one-right. In some countries, regulations mandate that where parallel runways are too close to each other, only one may be used at a time under certain conditions. At large airports with four or more parallel runways some runway identifiers are shifted by 1 to avoid the ambiguity that would result with more than three parallel runways. For example, in Los Angeles, this system results in runways 6L, 6R, 7L, 7R though all four runways are parallel at 69°. At Dallas/Fort Worth International Airport, there are five parallel runways, named 17L, 17C, 17R, 18L, 18R, all oriented at a heading of 175.4°. An airport with only three parallel runways may use different runway identifiers, such as when a third parallel runway was opened at Phoenix Sky Harbor International Airport in 2000 to the south of existing 8R/26L — rather than confusingly becoming the "new" 8R/26L it was instead designated 7R/25L, with the former 8R/26L becoming 7L/25R and 8L/26R becoming 8/26.
Runway designations may change over time because Earth's magnetic lines drift on the surface and the magnetic direction changes. Depending on the airport location and how much drift occurs, it may be necessary to change the runway designation; as runways are designated with headings rounded to the nearest 10°, this affects some runways sooner than others. For example, if the magnetic heading of a runway is 233°, it is designated Runway 23. If the magnetic heading changes downwards by 5 degrees to 228°, the runway remains Runway 23. If on the other hand the original magnetic heading was 226°, the heading decreased by only 2 degrees to 224°, the runway becomes Runway 22; because magnetic drift itself is slow, runway designation changes are uncommon, not welcomed, as they require an accompanying change in aeronautical charts and descriptive documents. When runway designations do change at major airports, it is changed at night as taxiway signs need to be changed and the huge numbers at each end of the runway need to be repainted to the new runway designators.
In July 2009 for example, London Stansted Airport in the United Kingdom changed its runway designations from 05/23 to 04/22 during the night. For fixed-wing aircraft it is advantageous to perform takeoffs and landings into the wind to reduce takeoff or landing roll and reduce the ground speed needed to attain flying speed. Larger airports have several runways in different directions, so that one can be selected, most nearly aligned with the wind. Airports with one runway are constructed to be aligned with the prevailing wind. Compiling a wind rose is in fact one of the preliminary steps taken in constructing airport runways. Note that wind direction is given as the direction the wind is coming from: a plane taking off from runway 09 faces east, into an "east wind" blowing from 090°. Runway dimensions vary from as small as 245 m long and 8 m wide in s
A car rental, hire car, or car hire agency is a company that rents automobiles for short periods of time ranging from a few hours to a few weeks. It is organised with numerous local branches, located near airports or busy city areas and complemented by a website allowing online reservations. Car rental agencies serve people who require a temporary vehicle, for example, those who do not own their own car, travelers who are out of town, or owners of damaged or destroyed vehicles who are awaiting repair or insurance compensation. Car rental agencies may serve the self-moving industry needs, by renting vans or trucks, in certain markets, other types of vehicles such as motorcycles or scooters may be offered. Alongside the basic rental of a vehicle, car rental agencies also offer extra products such as insurance, global positioning system navigation systems, entertainment systems, mobile phones, portable WiFi and child safety seats; the earliest known example of cars being offered for rent dates to 1906.
The German company Sixt was established in 1912 under the name Sixt Autofahrten und Selbstfahrer. Joe Saunders of Omaha, Nebraska first started with only one borrowed Model T Ford in 1916, but by 1917, his Ford Livery Company was renting out 18 Model Ts at 10 cents per mile; the company name became Saunders Drive-It-Yourself System and Saunders System. By 1926, Saunders had expanded to 56 cities. Saunders' company was bought by Avis in 1955. An early competitor to Saunders was Walter L. Jacobs, whose Chicago-based Rent-a-Car opened in 1918 with twelve Ford Model T; the company was bought in 1923 by John Hertz. In Britain, car rental started with Godfrey Davis, established in 1920, bought by Europcar in 1981; the sector expanded in the US. The growth in travel after World War II led to the establishment of several well known international companies, including National Car Rental, Enterprise Rent-A-Car, Thrifty Rent A Car, Budget Rent a Car. Car rental companies operate by purchasing or leasing a number of fleet vehicles and renting them to their customers for a fee.
Rental fleets can be structured in several ways – they can be owned outright, they can be leased, or they can be owned under a guaranteed buy-back program arranged directly through a manufacturer or manufacturer's financial arm. In the UK, the registration of rental cars can be concealed by using unfamiliar initials or subsidiaries, which can increase the resale value via manufacturer or third-party dealers. In North America, it is common to see rental companies with their own branded second-hand car dealers where the ex-rental stock is sold directly to the public. Alternatively, auctions are used in the United States and with the advent of digital platforms, rental cars have sold the vehicles directly to new and used car dealers bypassing the auction channels. Most car rental offices offer a range of vehicle sizes to suit a variety of budgets and space requirements and some additionally offer specialized vehicles to suit its location such as convertibles, prestige models, hybrid/electric vehicles, or SUVs and passenger vans.
At major airports or in larger cities, some independent car rental agencies offer high-end vehicles for rent. Some specialized companies offer older vehicles at reduced prices. To allow for a uniform classification and easy comparison of car rental prices, the Association of Car Rental Industry Systems and Standards has developed the ACRISS Car Classification Code coding system; this describes the size, door count, gearbox type, whether the car is air-conditioned, encoded into four letters. The first letter in the Acriss Code represents the general classification of the vehicle; the second letter specifies the vehicle variant on offer. The third letter is used to specify the transmission type, although it can be used to describe how many wheels drive the vehicle, the fourth letter describes the fuel type and whether the vehicle has air conditioning or not. Additional classifications based on seat numbers and trunk volume were set by the Belgian Rent a Car association in order to provide a unified system for assessing the car types in online reservation systems and airline global distribution systems.
Car rentals are subject to many conditions which vary from one country to another and from one company to another. The vehicle must be returned in the same condition it was rented in, must not exceed mileage restrictions, extra fees may be incurred. For insurance reasons, some companies stipulate a minimum and/or maximum rental age. In some cases, the minimum age for rental can be as high as 25 in countries where the minimum legal age to hold a driver's license is much lower, e.g. 14,15,16 or 17 in the United States. It is not uncommon for there to be a young driver surcharge for all drivers aged under 25. In all cases, a valid driver's license is required in order to rent a vehicle, some countries require an International Driving Permit; the majority of car rental companies require the use of a credit card to charge additional fees should a defect be found with the car on its return
Embraer ERJ family
The Embraer ERJ family is a series of twin-engine regional jets produced by Embraer, a Brazilian aerospace company. Aircraft in the series include the ERJ135, ERJ140, ERJ145, as well as the Legacy business jet and the R-99 family of military aircraft; each jet in the series is powered by two turbofan engines. The family's primary competition comes from the Bombardier CRJ regional jets; the ERJ145 was designed for a perceived new market for regional jet aircraft, where the increased speed and passenger appeal would outweigh the inherent fuel economy of the turboprop aircraft which were in service and in development. The 45–48 seat EMB145 was launched at the Paris Airshow in 1989 as an 18 ft stretch of the EMB 120 Brasilia developed for $150M plus $50M for training and marketing, one third the cost of the cancelled Short Brothers FJX project, its $11M unit cost would have been $3M less than the Canadair CRJ. The 400 kn jet would be powered by GE/Garrett CFE738s, Lycoming ALF 502s or Rolls-Royce plc/Allison Engine AB580s turbofans, to be selected in the summer of 1989.
It was targeted for a late 1992 introduction with six produced ramping to 60 per year in 1995. It aimed for half of a market for 1000 with break-even. Keeping 75% of the Brasilia parts and systems, the EMB145 Amazon aimed for a 1991 first flight; the stretch resulted from two 11 ft plugs of the 7 ft 6 in diameter fuselage in the front and behind the redesigned 538 sq ft wing. Its supercritical airfoil with a 14% root thickness had its chord extended at the leading edge with a slight sweepback, increased aspect ratio and winglets; the overwing podded. Designed for 500–600 nmi stages, up to 1,400 nmi with a reduced payload, it had a 36,375 lb maximum takeoff weight and a 21,045 lb operating empty weight. In early 1990, no engine supplier willing to share the risk of the $250 million development was yet selected; the Allison GMA3007 was selected in March 1990, with a maximum 40 kN take-off thrust and growth capability to 45 kN, first flight was due in September 1991. Rolls could participate in the fan and LP turbine, its original responsibility on the RB.580 joint development.
By May it had 296 commitments from 19 operators, was seeking external finance. In June, maiden flight was expected by the end of 1990 before mid-1993 deliveries for $11.5 million each, cabin pressurisation was increased to 0.55 bar from the Brasilia 0.48 bar. Following the engine selection, design was revised: length decreased from 27.08 to 26.74 m, span increased from 22.37 to 22.49 m, aspect ratio to 9.3 from 9.2. MTOW rose from 16,500 to 18,500 kg, basic operating weight from 9,560 to 10,940 kg, maximum fuel from 3,900 to 4,210 kg and payload from 4,500 to 5,160 kg. wing loading increased from 330 to 370 kg/m2, time-to-climb to FL400 gained 5 min to 30 min and maximum cruise rose from 405 kn to 428 kn at FL360. First delivery in 1993 was slated to Comair, which ordered 60. In November 1990, a major reduction in Brazilian government spending, which held 61% of its voting share, resulted in Embraer sacking 32% of its 12,800 employees and suspending development of the EMB-145 for six months.
In March 1991, a revised configuration started wind tunnel testing: the quarter chord wing sweep increased to 22.3° with underslung engines for lower aerodynamic drag. This reduced the span by 2 to 20.5 m, reducing its aspect ratio from 9.3 to 8.4 and wing area from 50 to 47 m2. The semi-monocoque wing has two main and one auxiliary spar and holds 4,500 kg of fuel, it has double-slotted fowler flaps and spoilers. To accommodate the underwing engines, the landing gear is longer, allowing using jetways, the fuselage was lengthened from 25.8 to 26 m. In June 1991, the Brazilian Government loaned $600 million to Embraer and in July the programme was re-evaluated while tooling was 80% complete. By November 1991, Embraer, still looking for partners to share the risk of the $350 million project, hoping to obtain Government approval by the end of the year. Sold at $12 million with an all-digital cockpit and 31.8 kN engines, it had letters of intent for 337 units. First flight slipped to 1992 and certification for late 1993.
After re-evaluation late in 1991, the layout was revised again with two rear-fuselage-mounted engines and a Mach 0.8 cruise speed would be tested in the wind tunnel. Seat pitch is 79 cm. A further stretch to 50–55 passengers is limited by a 12° rotation angle. Embraer continued to look for partners to share the $350 million development as first flight was expected for late 1994. In December 1994, Embraer was privatised for 80% to Brazilian and US investors while 20% was kept by the Brazilian Government, it first flew on August 1995 with 18 firm orders, 16 options and 127 letters of intent. A 1,300h flight-test programme for the prototype and three pre-series aircraft was planned within 13 months for certification in the third quarter of 1996, before deliveries in the fourth quarter of 1996 to launch customer Flight West; the $14.5 million aircraft is developed with risk-sharing partners including Spain's Gamesa producing the wing. The standard maximum ramp weight is 19,300 and 20,300 kg for the exten
Archive.today is an archive site which stores snapshots of web pages. It retrieves one page at a time similar to WebCite, smaller than 50MB each, but with support for modern sites such as Google Maps and Twitter. Archive.is uses headless browsing to record what embedded resources need to be captured to provide a high-quality memento, creates a PNG image to provide a static and non-interactive visualization of the representation. Archive.today can capture individual pages in response to explicit user requests. Since July 2013, archive.is supports the Memento Project application programming interface. Archive.today was founded in 2012. The site branded itself as archive.today, but in May 2015 changed the primary mirror to archive.is. In January 2019, it began to deprecate the archive.is domain in favor of the archive.today mirror. In March 2019 the site was blocked by several Australian internet providers in the aftermath of the Christchurch mosque shootings in an attempt to limit distribution of the footage of the attack.
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