Quadcopter

A quadcopter, also called a quadrotor helicopter or quadrotor, is a multirotor helicopter that is lifted and propelled by four rotors. Quadcopters are classified as rotorcraft, as opposed to fixed-wing aircraft, because their lift is generated by a set of rotors (vertically oriented propellers).

Quadcopters generally use two pairs of identical fixed pitched propellers; two clockwise (CW) and two counter-clockwise (CCW). These use independent variation of the speed of each rotor to achieve control. By changing the speed of each rotor it is possible to specifically generate a desired total thrust; to locate for the centre of thrust both laterally and longitudinally; and to create a desired total torque, or turning force.

Quadcopters differ from conventional helicopters which use rotors which are able to vary the pitch of their blades dynamically as they move around the rotor hub. In the early days of flight, quadcopters (then referred to as 'quadrotors') were seen as possible solutions to some of the persistent problems in vertical flight; torque-induced control issues (as well as efficiency issues originating from the tail rotor, which generates no useful lift) can be eliminated by counter-rotation and the relatively short blades are much easier to construct. A number of manned designs appeared in the 1920s and 1930s. These vehicles were among the first successful heavier-than-air vertical take off and landing (VTOL) vehicles. However, early prototypes suffered from poor performance, and latter prototypes required too much pilot work load, due to poor stability augmentation and limited control authority.

Quad

Quad may refer to:

An abbreviation for "quadruple" or four in many contexts, as in "quad exhaust pipes"

Architecture

Watch Dogs

Watch Dogs (stylized as WATCH_DOGS) is an open world action-adventure third-person shooter stealth video game developed and published by Ubisoft. It was released worldwide on 27 May 2014 for Microsoft Windows, PlayStation 3, PlayStation 4, Xbox 360 and Xbox One, while a Wii U version was released in November 2014. Set within a fictionalized version of Chicago, Illinois, the single-player story follows a hacker and his efforts to seek revenge after the killing of his niece. The open world design lets players freely roam Chicago, which includes the urban city, open countryside, and the run-down neighborhoods that surround downtown.

The game is played from a third-person perspective and its world is navigated on-foot or by vehicle. Players control Aiden Pearce, a highly skilled grey hat hacker who can hack into the "ctOS", a centralized operating system which manages the hyper-connected city of Chicago, and formed after the Northeast blackout of 2003 was caused by a hacker. An online multiplayer mode is also provided in the game, allowing up to eight players to engage in both cooperative and competitive gameplay in a recreation of the single-player setting.

San Francisco

San Francisco (/sæn frənˈsɪskoʊ/), officially the City and County of San Francisco, is the cultural, commercial, and financial center of Northern California and the only consolidated city-county in California. San Francisco encompasses a land area of about 46.9 square miles (121 km²) on the northern end of the San Francisco Peninsula, which makes it the smallest county in the state. It has a density of about 18,187 people per square mile (7,022 people per km²), making it the most densely settled large city (population greater than 200,000) in the state of California and the second-most densely populated major city in the United States after New York City. San Francisco is the fourth-most populous city in California, after Los Angeles, San Diego and San Jose, and the 13th-most populous city in the United States—with a Census-estimated 2014 population of 852,469. The city and its surrounding areas are known as the San Francisco Bay Area, and are a part of the larger OMB designated San Jose-San Francisco-Oakland combined statistical area, the fifth most populous in the nation with an estimated population of 8.6 million.

Simple Life

Simple Life may refer to:

Music

Movie & TV