Since the plane was so similar to the Boeing 707, no prototype Boeing 720 was needed. Any new systems were tested on the Boeing 367-80. The first 720 took off on November 23, 1959. It was first used by United Airlines, on July 5, 1960. 65 720s were made.
The "720B" was a different type of 720. It had JT3D turbofan engines. These engines made of thrust each. The JT3D engines burned less fuel and could make more thrust. The first 720B took off on October 6, 1960. The first airline to use it was American Airlines in March 1961. 89 720Bs were made. American Airlines also changed some of their normal 720s to 720Bs.
Since the Boeing 720 was so similar to the Boeing 707, it did not cost much to design. This meant that it still earned Boeing money, even though not many planes were sold. Boeing made 154 Boeing 720s and 720Bs from 1959 until 1967.
Although the Boeing 720 was similar to the Boeing 707-120, it was 9 ft (2.73 m) shorter. It was also lighter.
The 707 had emergency exits over the wings. These are called over-wing emergency exits. The back over-wing exit was removed. Two extra over-wing exits could be put in so that the plane could hold more passengers.
The 720's wing was taken from the 707, but some changes were made to it. The 720 had the same wingspan as the 707-120. For the 720, the wing had something called a wing root glove. This glove helped the wing make less drag.
Although the 720 first had turbojet engines, the Pratt & Whitney JT3D was much more popular. The JT3D was a turbofan engine. 720s which had the JT3D were called 720Bs. American Airlines changed some of their normal 720s to 720Bs.
The 720 used the engines to make air to pressurize the cabin. However, the engines could not make enough air to do this, so some small holes were put in above the engines for more air.
The Boeing 720 did not have an APU, so it needed power from the ground to power the plane until the engines were started (the engines could make electricity for the plane).
The first Boeing 720 was for United Airlines. It first flew on November 23, 1959. United Airlines first used the plane on July 5, 1960. It flew from Los Angeles to Denver and then Chicago. American Airlines was the second airline to use the 720. The Boeing 720 was replaced by the Boeing 727 during the 1960s.
The first 720 had its name changed to "The Starship". It was turned into a private plane used by rock bands. Led Zeppelin used it most, in the 1970s. A bar was put in, as well as beds, a shower, a lounge area, a TV and video cassette player.
Honeywell used the last Boeing 720 in the United States. It flew from Phoenix Sky Harbor International Airport. Honeywell used it for testing. Honeywell got rid of this plane on June 21 and 22, 2008. Honeywell replaced their Boeing 720 with a Boeing 757.
Pratt & Whitney Canada used the last 720 until 2010. It was used to test new engines. Pratt & Whitney Canada it with a Boeing 747SP. In May 2012, flown to the National Air Force Museum of Canada. It can now be seen there.
These airlines got new Boeing 720/720Bs:
The Boeing 720 has had 23 hull-loss accidents. It has been hijacked nine times. One plane was destroyed by a bomb in 1976. People died in 12 of the hull-loss accidents. 256 people have died on Boeing 720s. The three worst accidents were:
Sources: Boeing
King's Royal Hussars
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Pope Pius I (; died 154) was an Italian priest of the Roman Catholic Church and the 10th Pope, the official title is the Bishop of Rome from 140 until his death in 154.
Pius was born at Aquileia, in Northern Italy.
Pius became pope in 140.
He was the first sole Bishop of Rome during his reign. Previously, the Bishop of Rome was a council of Bishops with the Pope being the head of the council. His feast day is celebrated on July 11.
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The National Institute of Statistics and Census of Costa Rica (Spanish: "Instituto Nacional de Estadística y Censos de Costa Rica", or "INEC") is the government institution in charge of censuses and official surveys in the country. The main office is located in San José.
INEC was first called "Oficina Central de Estadística" in 1861. Later, in 1951, it was called "Dirección General de Estadística y Censos", until 1998, when INEC was its legal name. INEC ran its first census in 1864, and the last one was the 10th population and the 6th dwellings census, held in June 2011.
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Liberia is the capital and largest city of Guanacaste province in Costa Rica. The city is northwest of the national capital, San José. Liberia is often called "la ciudad blanca" (the white city) by its residents because of the white gravel once used to make the city’s roads and the whitewashed colonial houses that once made up a large part of the city.
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Nicoya is a town in Costa Rica's Guanacaste Province. It is one of the most important tourist zones. It serves as a transport hub to Guanacaste's beaches and national parks. The town is also the capital of the "cantón" of the same name (Nicoya Canton).
The town was built in an old colonial style. It was built in the Cordillera Volcánica de Guanacaste. Agriculture and cattle are the town's main economic activity.
In early 2006, a group of researchers led by adventure writer Dan Buettner and supported by National Geographic Magazine, the National Institute for Aging, and Alliance Healthcare, designated Nicoya as a Blue Zone. This designation is granted to global regions that are characterized by the longest life expectancies. Among the ideal Nicoyan lifestyle characteristics cited by the research were the water’s high calcium content, intense daily physical activity, year-long fruit consumption, and close inter-generational relationships.
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A lens is a clear (transparent) object (like glass, plastic or even a drop of water) that changes the way things look by bending the light that goes through it. They may make things appear larger, smaller, or upside-down. Some places lenses are used include spectacles (eyeglasses), contact lenses, cameras, projectors, microscopes, telescopes, magnifying glasses, etc. Each eye also has a lens.
They work by refraction, or the bending of light.
Lenses have three main shapes. Each different shape changes the image (making it bigger or smaller). The three types are:
The power of a lens is the reciprocal of its focal length:
P = 1/focal length.
The word "lens" comes from the Latin word for "lentil," because the earliest convex lenses in common use were shaped like the bean.
The oldest written record of lenses is in the ancient Greek play by Aristophanes called "Clouds", where lenses were used with sunlight to make fire.
Galileo Galilei is commonly believed to have used lenses to make the first known refracting telescope. However, he merely adapted and improved a design he learned from Dutch lensmakers such as Hans Lippershey. He was probably the first to use telescopes to make accurate astronomical observations, though.
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