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Aerostats
An aerostat (, via French) is a lighter-than-air aircraft that gains its lift through the use of a buoyant gas. Aerostats include unpowered balloons and powered airships. A balloon may be free-flying or tethered. The average density of the craft is lower than the density of atmospheric air, because its main component is one or more gasbags, a lightweight skin containing a lifting gas (which could be heated air or any gas of lower density than air) to provide buoyancy, to which other components such as a gondola containing equipment or people are attached. Especially with airships, the gasbags are often protected by an outer envelope. Aerostats are so named because they use aerostatic lift which is a buoyant force that does not require movement through the surrounding air mass, resulting in VTOL ability. This contrasts with the heavy aerodynes that primarily use aerodynamic lift which requires the movement of a wing surface through the surrounding air mass. The term has also be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airship
An airship or dirigible balloon is a type of aerostat or lighter-than-air aircraft that can navigate through the air under its own power. Aerostats gain their lift from a lifting gas that is less dense than the surrounding air. In early dirigibles, the lifting gas used was hydrogen, due to its high lifting capacity and ready availability. Helium gas has almost the same lifting capacity and is not flammable, unlike hydrogen, but is rare and relatively expensive. Significant amounts were first discovered in the United States and for a while helium was only available for airships in that country. Most airships built since the 1960s have used helium, though some have used hot air.A few airships after World War II used hydrogen. The first British airship to use helium was the ''Chitty Bang Bang'' of 1967. The envelope of an airship may form the gasbag, or it may contain a number of gas-filled cells. An airship also has engines, crew, and optionally also payload accommodation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lifting Gas
A lifting gas or lighter-than-air gas is a gas that has a density lower than normal atmospheric gases and rises above them as a result. It is required for aerostats to create buoyancy, particularly in lighter-than-air aircraft, which include free balloons, moored balloons, and airships. Only certain lighter than air gases are suitable as lifting gases. Dry air has a density of about 1.29 g/L (gram per liter) at standard conditions for temperature and pressure (STP) and an average molecular mass of 28.97 g/mol, and so lighter-than-air gases have a density lower than this. Gases used for lifting Hot air Heated atmospheric air is frequently used in recreational ballooning. According to the Ideal gas law, an amount of gas (and also a mixture of gases such as air) expands as it is heated. As a result, a certain volume of gas has a lower density as the temperature is higher. The average temperature of air in a hot air balloon is about . Hydrogen Hydrogen, being the li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heavier-than-air Aircraft
An aircraft is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or by using the Lift (force), dynamic lift of an airfoil, or in a few cases the Powered lift, downward thrust from jet engines. Common examples of aircraft include airplanes, helicopters, airships (including blimps), Glider (aircraft), gliders, Powered paragliding, paramotors, and hot air balloons. The human activity that surrounds aircraft is called ''aviation''. The science of aviation, including designing and building aircraft, is called ''aeronautics.'' Aircrew, Crewed aircraft are flown by an onboard Aircraft pilot, pilot, but unmanned aerial vehicles may be remotely controlled or self-controlled by onboard computers. Aircraft may be classified by different criteria, such as lift type, Powered aircraft#Methods of propulsion, aircraft propulsion, usage and others. History Flying model craft an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-rigid Airship
A blimp, or non-rigid airship, is an airship (dirigible) without an internal structural framework or a keel. Unlike semi-rigid and rigid airships (e.g. Zeppelins), blimps rely on the pressure of the lifting gas (usually helium, rather than hydrogen) inside the envelope and the strength of the envelope itself to maintain their shape. Principle Since blimps keep their shape with internal overpressure, typically the only solid parts are the passenger car (gondola) and the tail fins. A non-rigid airship that uses heated air instead of a light gas (such as helium) as a lifting medium is called a hot-air airship (sometimes there are battens near the bow, which assist with higher forces there from a mooring attachment or from the greater aerodynamic pressures there). Volume changes of the lifting gas due to temperature changes or to changes of altitude are compensated for by pumping air into internal ballonets (air bags) to maintain the overpressure. Without sufficient overpressur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Observation Balloon
An observation balloon is a type of balloon that is employed as an aerial platform for intelligence gathering and artillery spotting. Use of observation balloons began during the French Revolutionary Wars, reaching their zenith during World War I, and they continue in limited use today. Synonyms include espionage balloon, reconnaissance balloon, or surveillance balloon. Historically, observation balloons were filled with hydrogen. The balloons were fabric envelopes filled with hydrogen gas, whose flammable nature led to the destruction of hundreds of balloons on both sides. Observers manning these observation balloons frequently had to use a parachute to evacuate their balloon when it came under attack. To avoid the potentially flammable consequences of hydrogen, observation balloons after World War I were often filled with non-flammable helium. Typically, balloons were tethered to a steel cable attached to a winch that reeled the gasbag to its desired height (usually 1,000-1,5 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blimps
A blimp, or non-rigid airship, is an airship (dirigible) without an internal structural framework or a keel. Unlike semi-rigid and rigid airships (e.g. Zeppelins), blimps rely on the pressure of the lifting gas (usually helium, rather than hydrogen) inside the envelope and the strength of the envelope itself to maintain their shape. Principle Since blimps keep their shape with internal overpressure, typically the only solid parts are the passenger car (gondola) and the tail fins. A non-rigid airship that uses heated air instead of a light gas (such as helium) as a lifting medium is called a hot-air airship (sometimes there are battens near the bow, which assist with higher forces there from a mooring attachment or from the greater aerodynamic pressures there). Volume changes of the lifting gas due to temperature changes or to changes of altitude are compensated for by pumping air into internal ballonets (air bags) to maintain the overpressure. Without sufficient overpressur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barrage Balloon
A barrage balloon is a large uncrewed tethered balloon used to defend ground targets against aircraft attack, by raising aloft steel cables which pose a severe collision risk to aircraft, making the attacker's approach more difficult. Early barrage balloons were often spherical. The design of the kite balloon, having a shape and cable bridling which stabilises the balloon and reduces drag, meant that it could be operated at higher wind speeds than a spherical balloon. Some examples carried small explosive charges that would be pulled up against the aircraft to ensure its destruction. Barrage balloons are not practical against very high-altitude flying aircraft, due to the weight of the long cable required. First World War France, Germany, Italy and the United Kingdom used barrage balloons in the First World War. While the French and German forces had developed kite balloons, early British barrages balloons were spherical. Sometimes, especially around London, several balloons wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Espionage Balloon
Espionage, spying, or intelligence gathering is the act of obtaining secret or confidential information (intelligence) from non-disclosed sources or divulging of the same without the permission of the holder of the information for a tangible benefit. A person who commits espionage is called an ''espionage agent'' or ''spy''. Any individual or spy ring (a cooperating group of spies), in the service of a government, company, criminal organization, or independent operation, can commit espionage. The practice is clandestine, as it is by definition unwelcome. In some circumstances, it may be a legal tool of law enforcement and in others, it may be illegal and punishable by law. Espionage is often part of an institutional effort by a government or commercial concern. However, the term tends to be associated with state spying on potential or actual enemies for military purposes. Spying involving corporations is known as industrial espionage. One of the most effective ways to ga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fire Balloon
An incendiary balloon (or balloon bomb) is a balloon inflated with a lighter-than-air gas such as hot air, hydrogen, or helium, that has a bomb, incendiary device, or Molotov cocktail attached. The balloon is carried by the prevailing winds to the target area, where it falls or releases its payload. Historical use Early proposals In 1792, Joseph-Michel Montgolfier proposed using balloons to drop bombs on British forces and ships in Toulon.''Military Aircraft, Origins to 1918: An Illustrated History of Their Impact'' Justin D. Murphy, page 161 In 1807, Denmark attempted to construct a hand-propelled dirigible that would bomb British ships blockading Copenhagen from the air. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kite Balloon
A kite balloon is a tethered balloon which is shaped to help make it stable in low and moderate winds and to increase its lift. It typically comprises a streamlined envelope with stabilising features and a harness or yoke connecting it to the main tether and a second harness connected to an observer's basket. Kite balloons are able to fly in higher winds than ordinary round balloons which tended to bob and spin in windy conditions.Ege, 1973, pp.128–129 They were extensively used for military observation during World War I and similar designs were used for anti-aircraft barriers, as barrage balloons in both world wars. Design and development Developed in Germany from 1893 by ''Parseval'' and ''Sigsfeld'', the main component of a kite balloon is its tubular-shaped envelope, similar to that of a non-rigid airship, giving it its British and French nicknames of "sausage". This was inclined at a nose up angle to about 30–40° from the horizontal, which resulted in it producing some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
