Unpowered aircraft can remain airborne for a significant period of time without onboard propulsion. They can be classified as gliders, lighter-than-air balloons and tethered kites. In the case of kites, lift is obtained by tethering to a fixed or moving object, perhaps another kite, to obtain a flow of wind over the lifting surfaces. In the case of balloons, lift is obtained through inherent buoyancy and the balloon may or may not be tethered. Free balloon flight has little directional control. Gliding aircraft include sailplanes, hang gliders, and paragliders that have full directional control in free flight.
Project Mogul was a top secret project by the US Army Air Forces involving microphones flown on high-altitude balloons, whose primary purpose was long-distance detection of sound waves generated by Soviet atomic bomb tests. The project was carried out from 1947 until early 1949. It was a classified portion of an unclassified project by New York University (NYU) atmospheric researchers. The project was moderately successful, but was very expensive and was superseded by a network of seismic detectors and air sampling for fallout, which were cheaper, more reliable, and easier to deploy and operate.
Surveillance aircraft are aircraft used for surveillance. They are primarily operated by military forces and government agencies in roles including intelligence gathering, maritime patrol, battlefield and airspace surveillance, observation, and law enforcement.
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag or aerodynamic lift. A major application is to support people, for recreation or as a safety device for aviators, who can exit from an aircraft at height and descend safely to earth.
A military aircraft is any fixed-wing or rotary-wing aircraft that is operated by a legal or insurrectionary military of any type. Some military aircraft engage directly in aerial warfare, while others take on support roles:
A reconnaissance aircraft is a military aircraft designed or adapted to perform aerial reconnaissance with roles including collection of imagery intelligence, signals intelligence, as well as measurement and signature intelligence. Modern technology has also enabled some aircraft and UAVs to carry out real-time surveillance in addition to general intelligence gathering.
The Royal Flying Corps (RFC) was the air arm of the British Army before and during the First World War until it merged with the Royal Naval Air Service on 1 April 1918 to form the Royal Air Force. During the early part of the war, the RFC supported the British Army by artillery co-operation and photographic reconnaissance. This work gradually led RFC pilots into aerial battles with German pilots and later in the war included the strafing of enemy infantry and emplacements, the bombing of German military airfields and later the strategic bombing of German industrial and transport facilities.
A barrage balloon is a type of airborne barrage, a large uncrewed tethered balloon used to defend ground targets against aircraft attack, by raising aloft steel cables which pose a severe risk of collision with hostile aircraft, making the attacker's approach difficult and hazardous. Early barrage balloons were often spherical. The kite balloon, having a shape and cable bridling that stabilizes the balloon and reduces drag, 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 at higher altitudes due in large part to the cable's weight.
Aerial warfare is the use of military aircraft and other flying machines in warfare. Aerial warfare includes bombers attacking enemy installations or a concentration of enemy troops or strategic targets; fighter aircraft battling for control of airspace; attack aircraft engaging in close air support against ground targets; naval aviation flying against sea and nearby land targets; gliders, helicopters and other aircraft to carry airborne forces such as paratroopers; aerial refueling tankers to extend operation time or range; and military transport aircraft to move cargo and personnel.
World War I was the first major conflict involving the large-scale use of aircraft. Tethered observation balloons had already been employed in several wars and would be used extensively for artillery spotting. Germany employed Zeppelins for reconnaissance over the North Sea and Baltic and also for strategic bombing raids over Britain and the Eastern Front.
In aeronautics, a balloon is an unpowered aerostat, which remains aloft or floats due to its buoyancy. A balloon may be free, moving with the wind, or tethered to a fixed point. It is distinct from an airship, which is a powered aerostat that can propel itself through the air in a controlled manner.
Mid-air retrieval is a technique used in atmospheric reentry when the reentering vehicle is incapable of a satisfactory unassisted landing. The vehicle is slowed by means of parachutes, and then a specially-equipped aircraft matches the vehicle's trajectory and catches it in mid-air.
Balloons and kites were the first inventions used in aerial warfare and their primary role was reconnaissance. Balloons provided a reliable and stable means of elevating an observer high over the battlefield to obtain a birds-eye view of troop positions and movements. An early instrument of aerial intelligence collection, they were also useful for creating accurate battlefield maps, an important ingredient for battlefield success. Incendiary balloons also have a long history. The incendiary balloons carry hot air or something that can catch fire to destroy enemy territory. They could also hold small bombs for combat. The history of military ballooning dates back to the late 18th century, when the Montgolfier brothers, Joseph-Michel and Jacques-Étienne, first demonstrated the potential of hot-air balloons for military use. The first recorded military use of balloons was during the French Revolutionary Wars, when the French military used balloons to gather intelligence on the movements of the enemy. Balloons were also used during the American Civil War, where they were used for reconnaissance and communication. Balloons had a decline after several incidents in the interwar period.
Project Genetrix, also known as WS-119L, was a program run by the U.S. Air Force, Navy, and the Central Intelligence Agency during the 1950s under the guise of meteorological research. It launched hundreds of surveillance balloons that flew over China, Eastern Europe, and the Soviet Union to collect intelligence on their nuclear capabilities. The Genetrix balloons were manufactured by the aeronautical division of General Mills. They were about 20 stories tall, carried cameras and other electronic equipment, and reached altitudes ranging from 30,000 to over 60,000 feet, well above the reach of any contemporary fighter plane. The overflights drew protests from target countries, while the United States defended its action.
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.
Georgy (Yegor) Alekseyevich Prokofiev was a Soviet Air Forces balloonist who coordinated a military stratospheric balloon program in 1931–1939. On September 30, 1933, USSR-1 under Prokofiev's command set an unofficial world altitude record of 18,501 metres (60,699 ft).
Between 1946 and 1960, the United States Air Force conducted aerial reconnaissance flights over the Soviet Union in order to determine the size, composition, and disposition of Soviet forces. Aircraft used included the Boeing B-47 Stratojet bomber and—from 1956—the Lockheed U-2 spy plane specifically designed for high-altitude reconnaissance flight. The overflight program was ended following the 1960 U-2 incident.
Aerial reconnaissance using heavier-than-air machines was an entirely new science that had to be improvised step-by-step. Early operations were low-level flights with the pilot often dismounting from the plane to report verbally to the nearest officers. Photographic support was urgently developed, initially requiring a full-time photographer on board to handle the heavy, awkward equipment. The interpreting of aerial images was an important new speciality, essential for accurate mapping. By 1915, air-to-ground radio was in use for reconnaissance pilots.
Parseval-Sigsfeld kite balloon was a type of non-rigid military observation balloon, designed in 1898 by August von Parseval and Hans Bartsch von Sigsfeld. Its aerodynamic shape and the air capsule ensured a stable position thanks to the force of the wind, in a similar way to how kites are stabilized; for this reason it was known as the kite balloon.
Caquot kite balloon was a type of non-rigid military observation balloon, designed in 1915 by Albert Caquot. The type became widely used by Allied forces in World War I warfare for multiple observation or naval defence uses and later also as a anti-aircraft barrage balloon.
