Backpack helicopter

A backpack helicopter is a helicopter motor and rotor and controls assembly that can be strapped to a person's back, so that they can walk about on the ground wearing it, and can use it to fly. It uses a harness like a parachute harness and should have a strap between the legs (so that the pilot does not fall out of the harness during flight). Some designs may use a ducted fan design to increase upward thrust. Several inventors have tried to make backpack helicopters, with mixed results.

Typically, a backpack helicopter differs from a conventional helicopter in two main ways:

First, there is no tail rotor, and the main rotors are contra-rotating. Yaw is controlled by fine adjustment of a differential gear in the rotor drive transmission. When one rotor is adjusted to spin slightly faster than the other, it induces yaw (turning motion).

Second, the rotors are fixed pitch, which assists with simplicity; this means, however, that in the event of engine failure autorotation is impossible. Usually, a ballistic parachute would be incorporated for safety.

Heli

Heli, also heli, heli- may refer to:

People

Places

Companies

Other uses

A prefix of a word

heli- indicating a reference to helicopters; examples may or may not be hyphenated according to local or popular usage:

Heli (name)

Heli is a Finnish female given name. Its nameday is the 20th of February. It might have originated as a variation of the name Helena, although it is not certain.

It reached the peak of its popularity in the middle of the 20th century. As of December 2012, there are more than 17,000 people registered in Finland with this name.

The name also exists in Estonia.

Notable people

References

Heli (film)

Heli is a 2013 independent Mexican crime drama film directed by Amat Escalante and produced by Jaime Romandía. Featuring newcomers Armando Espitia, Andrea Vergara, Linda González, and Juan Eduardo Palacios, the film premiered in competition for the Palme d'Or at the 2013 Cannes Film Festival. Escalante won the Best Director award at the ceremony. While being appreciative of the film's technical aspects, film critics were divided in their opinion of the film itself. Heli was selected to represent Mexico at the 86th Academy Awards for Best Foreign Language Film, but it was not nominated.

Plot

Heli tells the story of the titular protagonist (played by Armando Espitia), a seventeen-year-old boy living with his wife (Linda González) and his sister, Estela (played by Andrea Vergara). The film follows the arcs of these characters and Estela's boyfriend (played by Juan Eduardo Palacios) as they struggle with drugs, violence, and corruption.

Heli is a young man working in a car assembly factory; he lives with his father who also works there, his wife Sabrina, his baby son Santiago and his sister Estela. His life is normal, slow, and without economical prospects, and he suffers from a troubled relationship with his wife.

Pack

Pack or packs may refer to:

Places

People

Air cycle machine

An air cycle machine (ACM) is the refrigeration unit of the environmental control system (ECS) used in pressurized gas turbine-powered aircraft. Normally an aircraft has two or three of these ACM. Each ACM and its components are often referred as an air conditioning pack. The air cycle cooling process uses air instead of a phase changing material such as Freon in the gas cycle. No condensation or evaporation of a refrigerant is involved, and the cooled air output from the process is used directly for cabin ventilation or for cooling electronic equipment.

History

Air cycle machines were first developed in the 19th century for providing chilling on ships. The technique is a reverse Brayton cycle (the thermodynamic cycle of a gas turbine engine) and is also known as a Bell Coleman cycle or "Air-Standard Refrigeration Cycle".

Technical details

The usual compression, cooling and expansion seen in any refrigeration cycle is accomplished in the ACM by a centrifugal compressor, two air-to-air heat exchangers and an expansion turbine.

Playing card

A playing card is a piece of specially prepared heavy paper, thin cardboard, plastic-coated paper, cotton-paper blend, or thin plastic, marked with distinguishing motifs and used as one of a set for playing card games. Playing cards are typically palm-sized for convenient handling.

A complete set of cards is called a pack (UK English), deck (US English), or set (Universal), and the subset of cards held at one time by a player during a game is commonly called a hand. A pack of cards may be used for playing a variety of card games, with varying elements of skill and chance, some of which are played for money (e.g., poker and blackjack games at a casino). Playing cards are also used for illusions, cardistry, building card structures, cartomancy and memory sport.

The front (or "face") of each card carries markings that distinguish it from the other cards in the pack and determine its use under the rules of the game being played. The back of each card is identical for all cards in any particular pack to create an imperfect information scenario. Usually every card will be smooth; however, some packs have braille to allow blind people to read the card number and suit.