Aircraft interacting with the atmosphere fall into two broad categories: lighter than air and heavier than air. At the heart of this division are different principles of flight. In the first case, the Archimedes law is used to create the lifting force, that is, they use the aerostatic principle. For devices that are heavier than air, the lifting force arises due to aerodynamic interaction with the atmosphere. We will consider the first category - aircraft are lighter than air.
Floating in the air ocean
A device that uses Archimedean - buoyant - force to lift it is called a balloon. This is an aircraft equipped with a shell filled with hot air or gas, which has a lower density than the surrounding atmosphere.
The difference in the density of the gas inside and outside the shell causes a pressure differential, due to which there is an aerostatic buoyancy force. This is an example of the operation of the law of Archimedes.
The lift ceiling of aircraft is lighter than air is determined by the volume and elasticity of the shell, the method of filling and atmospheric factors - primarily the decrease in air density with height. The record for a manned climb today is 41.4 km, unmanned - 53 km.
General classification
A balloon is the common name for a whole class of aircraft. First of all, all balloons are divided into uncontrolled (balloons) and controlled (airships). There are also tethered balloons used in various fields to solve certain special tasks.
1. Balloons. The principle of balloon flight does not imply the ability to control the aircraft in a horizontal plane. The ball does not have an engine and rudders, therefore, its pilot cannot choose the speed and direction of his flight. On the ball, it is possible to adjust the height with the help of valves and ballast, but otherwise its flight is a drift in air currents. Three types of balloons are distinguished by the type of filler:
- Hot air balloons.
- Gas filled charlers. Most often, hydrogen and helium were used (and continue to be used) for these purposes, but both of them have their own drawbacks. Hydrogen is extremely flammable and forms an explosive mixture with air. Helium is too expensive.
- Rosiers are balloons that combine both types of fillers.
2. Airships (dirigeable in French - “controlled”) are aircraft, the design of which includes a power plant and controls. In turn, airships are classified according to many criteria: by the stiffness of the shell, by the type of power unit and propulsors, by the method of creating buoyancy and so on.
The early history of aeronautics
The very first reliable device to fly into the air with the help of Archimedean force is probably the Chinese lantern. Chronicles mention paper bags that rise under the influence of hot air from a lamp. It is known that such lamps were used in military affairs as a means of signaling in the II-III centuries; it is possible that they were known earlier.
Western technical thought came to the idea of the possibility of such devices by the end of the 17th century, realizing the futility of attempts to create muscle-fly devices for human flight. So, the Jesuit Francesco Lana designed an aircraft lifted using evacuated metal balls. However, the technical level of the era in no way allowed us to carry out this project.
In 1709, the priest Lorenzo Guzmao demonstrated to the Portuguese royal court an aircraft, which was a thin shell, in which the air was heated by a brazier suspended from below. The device managed to climb a few meters. Unfortunately, nothing is known about Guzmao's further activities.
The beginning of aeronautics
The first aircraft lighter than air, the successful test of which was officially recorded, was the balloon of the brothers Joseph-Michel and Jacques-Etienne Montgolfier. On June 5, 1783, this balloon flew over the French town of Annone, breaking 2 km in 10 minutes. The maximum lifting height was about 500 meters. The shell of the ball was a canvas covered with paper from the inside; smoke from the burning of wet wool and straw was used as a filler, for a long time after that it was called “hot air gas”. The aircraft, respectively, was called the "hot air balloon".
Almost simultaneously, on August 27, 1783, a balloon filled with hydrogen, designed by Jacques Charles, soared into the air in Paris. The shell was made of silk, impregnated with a solution of rubber in turpentine. Hydrogen was produced by exposure to iron filings by sulfuric acid. A ball 4 meters in diameter was filled for several days, having spent more than 200 kilograms of acid and almost half a ton of iron. The first charlier in front of 300 thousand spectators disappeared into the clouds. The balloon shell, which exploded high in the atmosphere, fell 15 minutes later in the countryside near Paris, where it was destroyed by frightened locals.
First manned flights
The first passengers of the aeronautical apparatus, which took off at Versailles on September 19, 1783, were most likely nameless. A rooster, a duck and a ram flew in a hot air balloon basket lasting 10 minutes and a range of 4 km, after which they landed safely.
The first flight of people on a hot air balloon took place on November 21 of the same breakthrough year 1783. The physicist Jean-Francois Pilatre de Rosier and his two comrades made it. Then, in November, de Rosier consolidated his success with the aeronautics enthusiast Marquis Francois Laurent d'Arland. Thus, it was proved that the state of free flight is safe for humans (there were still doubts about this).
On December 1, 1983 (a truly significant year for aeronautics!), The charlier also ascended into the air, carrying on board a crew, which, in addition to J. Charles himself, was mechanic N. Robert.
In subsequent years, flying with both types of balloons was practiced very widely, but gas balloons still had some advantage, since hot air balloons consumed a lot of fuel and developed low lift. Rosiers - balls of a combined type - were too dangerous.
Aerostat in the service
Balloons very soon began to serve not only entertainment purposes, but also the needs of science and military affairs. Even during the first flight, Charles and Robert were engaged in measurements of air temperature and pressure at high altitude. Subsequently, scientific observations were often carried out with balloons. They were used to study the Earth’s atmosphere and geomagnetic field, and later cosmic rays. Balloons are widely used as meteorological probes.
Balloon military service began during the French Revolution, when tethered balloons began to be used to monitor the enemy. Subsequently, such devices were used for high-altitude reconnaissance and fire adjustment not only in the 19th, but also in the first half of the 20th century. During World War II, tethered barrage balloons were an element of air defense of large cities. During the Cold War, high-altitude balloons were used by NATO intelligence against the USSR. In addition, submarine long-distance communications systems using tethered balloons were developed.
Higher and higher
A stratostat is a balloon of the “sharlier” type, which, due to its design features, can rise into the upper rarefied layers of the Earth’s atmosphere — the stratosphere. If the flight is manned, such a balloon is filled with helium. In the case of an unmanned flight, it is filled with cheaper hydrogen.
The idea of using a balloon at high altitudes belongs to D.I. Mendeleev and was expressed by him in 1875. The safety of the crew, according to the scientist, was to be ensured by a sealed balloon nacelle. However, the creation of such an aircraft requires a high technical level, which was achieved only by 1930. Thus, flight conditions require a special device for a stratospheric balloon, the use of light metals and alloys, the development and implementation of ballast discharge systems and thermal control of the nacelle, and much more.
The first stratospheric balloon FNRS-1 was created by the Swiss scientist and engineer Auguste Picard, who, together with P. Kipfer, first climbed into the stratosphere on May 27, 1931, reaching an altitude of 15,785 m.
The creation of these aircraft received special development in the USSR. Many records during flights to the stratosphere were set in the second half of 1930 by Soviet aeronauts.
In 1985, during the implementation of the Soviet space project “Vega”, two stratostats filled with helium were launched in the atmosphere of Venus. They worked at an altitude of about 55 km for more than 45 hours.
First airship
Attempts to create a horizontal-controlled balloon were made almost immediately after the first flights of hot air balloons and sharlers. J. Meunier proposed to give the aircraft an ellipsoidal shape, a double shell with a balloon and equip it with propellers driven by muscular force. However, the implementation of this idea required the efforts of 80 people ...
For many years, due to the lack of a power unit suitable for flight conditions, the controlled balloon remained only a dream. It was possible to carry out it only in 1852 by Henri Giffard, whose machine made its first flight on September 24. Giffard’s airship was equipped with a rudder and a 3 horsepower steam engine that rotated the propeller. The volume of the gas-filled shell was 2500 m 3 . The soft shell of the airship was subject to subsidence due to changes in atmospheric pressure and temperature.
For a long time after the flight of the first airship, engineers tried to achieve the optimal combination of engine power and weight, to improve the design of the shell and nacelle of the device. In 1884, it was possible to put an electric motor on the airship, in 1888 - a gasoline engine. Further success of the airship was associated with the development of machines with a hard shell.
The success and tragedy of zeppelins
A breakthrough in the creation of airships is associated with the name of Count Ferdinand von Zeppelin. The flight of his first car, built in Germany on Lake Constance, took place on July 2, 1900. Despite the breakdown that led to an emergency landing on the lake, the design of hard airships after further testing was considered successful. They managed to modify the design of the machine, and the airship Ferdinand von Zeppelin was purchased by the German military. In the First World War, zeppelins were already used by all the leading powers.
The rigid shell of the airship consisted of a metal frame of a cigar-shaped configuration, covered with a fabric with a cellon coating. Inside the frame, gas cylinders filled with hydrogen were attached. The aircraft was equipped with aft steering wheels and stabilizers, had several engines with propellers. Tanks, cargo and engine compartments, passenger decks were located in the lower part of the frame. The volume of the airship could reach 200 m 3 , the length of the hull was huge. For example, the length of the infamous Hindenburg was 245 m. Driving such a huge machine was extremely difficult.
In the period between the world wars, zeppelins were widely used as a vehicle, including transatlantic flights. However, a number of disasters, the most famous of which was the crash as a result of the fire of the Hindenburg airship, and the high cost of these vehicles did not play in their favor. But the main factor in curtailing the airship was the upcoming World War II. The nature of the warfare required the massive use of high-speed aviation, and the airships in it did not find a serious place. As a result, and after the war, there was no revival of them as a widely used vehicle.
Balloons and modernity
Despite the development of aviation, airships and balloons did not sink into oblivion, on the contrary, by the end of the 20th century interest in them increased again. This is due to success in the development of high-tech materials and computer control and safety systems, as well as to the relative reduction in the cost of helium production. Airships may well revive as machines that perform important tasks in some special industries, for example, in servicing oil platforms or in transporting bulky goods in hard-to-reach areas. The military again began to show some interest in these aircraft.
Miniature airships are also used to solve various applied problems, for example, when shooting for television broadcasts.
Accustomed to airplanes, helicopters and spacecraft, the public is once again experiencing an interest in aeronautics. Balloons festivals in different countries of the world, including Russia, became a frequent occurrence. Thanks to heat-resistant lightweight materials and special burners, working from gas cylinders, hot air balloons survive a second youth. Solar hot air balloons have also been invented, generally not requiring the burning of fuel.
Of great interest to athletes and spectators are the competitions and enchanting mass starts of many devices held at each balloon festival. These events have long become an integral part of the entertainment industry.
It is difficult to predict exactly what the future awaits aircraft lighter than air. But we can confidently say: they have a future.