The words "aviation" and "aeronautics" until the 1920s. XX century were synonyms. At the beginning of the last century, everything changed. Aeronautics began to call moving using devices that are lighter than air, and aviation - flying on airplanes. That is, ships that are heavier than air. In the article we will consider in detail the history of aeronautics, the physics of the process.
Why does a balloon take off
Recall the conditions under which a body immersed in a liquid emerges. If its density is less than the density of the liquid. The same goes for gas, in particular air. A balloon (balloon) will take off if there is a lighter (compared to air) gas inside its shell. The balloon also “pops up”, though it is hindered by gravity acting on the shell.
We list the forces acting on the ball. The first is the shell's gravity. Secondly, it is the gravity of the gas. The gas inside the ball also has mass, which means that gravity also acts on it. We assume that these two forces together are not able to overcome the Archimedean force, which acts on the gas from the air. If so, then the ball can take off and lift the load.
Lifting power
Consider the key provisions of aeronautics physics. If we tie the balloon to the ground, it will stretch upward, pulling the rope with a force called lift. To calculate it, it is necessary to subtract the weight of the gas together with the shell from the strength of Archimedes. Weight is the sum of the shell’s gravity and gas’s gravity. The force of Archimedes is equal to the product of air density and the acceleration of gravity and the volume of the ball.
The lifting force is greater, the lighter the shell. It is the larger, the larger the volume of the ball and the greater the difference between the density of air and the density of gas. So, if you need to get maximum lifting force, you need to fill the ball with the lightest gas. This is hydrogen. However, there is one problem: it is very flammable, especially when mixed with oxygen. Therefore, most often the balloons are inflated with helium.
Balloon
A balloon is a device that is filled with light gas. The photo shows a balloon that is used to study the weather. This is the so-called balloon probe. It is filled with helium, a radio transmitter is suspended from below, transmitting information about temperature, pressure, air humidity at different heights. Balloons are used in meteorology.
There is the possibility of creating aeronautical apparatuses that are relatively safe, and very cheap, and that do not require either hydrogen or helium. Instead of these gases, the shell is filled with ordinary air, but hotter. Such a balloon was invented by the French, the Montgolfier brothers. It was a grand event! The figure shows the first thermal balloon. A fire was lit from below, hot air filled the shell, and the ball soared upward. At a certain height, he stopped rising. To continue the ascent, ballast was dropped from the apparatus. If you had to go down, then reduce the fire.
Stratospheric balloon
At very high altitudes, air density decreases. Consequently, the lifting force also decreases. How can it be improved? It is necessary to increase the volume, so those aeronautical devices that rise very high into the stratosphere are huge. Such vessels are called stratospheres.
Recently, one extreme player set a record: he climbed a stratosphere balloon to an altitude of 39 km and in free fall exceeded the speed of sound. This is Felix Baumgartner. The photo shows the stratostat that he used. Its dimensions are about 100 m, which is commensurate with the height of the Statue of Liberty. The aircraft is filled with 85 thousand m 3 of helium, the so-called gondola, where the passenger is located, is suspended below.
Airship
Consider the physics of aeronautics. Balloon and stratostat move where the wind blows. Experienced balloonists know that winds are different at different altitudes. Therefore, they adjust the height of the balloon so that the wind blows where they need to. If you need to sail from point A to point B regardless of the wind, you should adapt a special screw to the device, like in an airplane, which will help you move in the right direction. Such a device is called an airship. These are usually very large systems. The device is filled with helium, a gondola is attached at the bottom, and a propeller is located under its bottom. The cables that hang from the bottom of the airship are needed to secure it to the ground.
One of the most famous airships in the world was built by the Germans in the early 30s. XX century, it was called "Gendenburg." The fate of this device is somewhat similar to the fate of the Titanic. He was an unusually comfortable ship. Its length was about a quarter kilometer. On board were placed about 100 people. The airship was driven by 4 engines.
May 6, 1937 the ship suffered an accident. It was necessary to fill it exclusively with helium, and at that time helium could be obtained only in the USA. Since this was the time of Hitler's rule, the Americans flatly refused to sell gas to the Nazis. The airship was filled with hydrogen. Extraordinary precautions were taken to prevent a fire. During the landing, there was pre-storm weather, and there was a strong electric field in the air. The airship flew from Germany (Frankfurt) to New York, across the Atlantic Ocean. When it was planted, a spark appeared, due to a hydrogen leak, the airship caught fire. Of the 97 passengers killed 35, another person was killed on the ground.
The first steps of aeronautics in our country: a little history
They learned about aeronautics in Russia during the time of Catherine II. Her envoy in France announced the invention of the Montgolfier brothers.
The sensation was circulated by Russian newspapers, and later a book was published that explained the principle of the balloon. It was read by Euler, a member of the Academy of Sciences in St. Petersburg. He studied aeronautics physics and constructed the first balloon. After the only flight of this device, Catherine II banned aeronautics by her decree because of the danger of fire. For violation of the decree was prescribed a fine of 20 rubles.
Under Catherine II, no one violated the decree, but when Alexander I ruled the country, the balloon flew again. This happened in Moscow, the balloon was controlled by a man named Terzi. He presented aeronautics as a circus performance and earned a lot of money on it.
In 1803, the famous aeronaut Garnerin and his wife were invited to Russia. They demonstrated the capabilities of the balloon to an amazed audience, among which was Emperor Alexander I.
Use of the apparatus in science and military affairs
Garnerin made more than one demonstration flight before scientists became interested in ballooning. The Academy of Sciences sent one of its members, Zakharov, to fly to observe the atmosphere. The academician took with him a lot of measuring instruments and reagents. Due to the fact that the balloon was not too large to gain height, it was necessary to drop not only ballast, but also many appliances, food and even a dress coat.
In 1812, at the court of the emperor, they were sure that Napoleon would nevertheless go to war against Russia. We decided to use the aircraft for military purposes. Work began on the construction of the airship. 150 carpenters and blacksmith masters created a gondola, and seamstresses worked on the creation of a shell. The airship had a steering wheel for changing flight altitude, as well as paddles for maneuvering. The gondola had a hatch to drop landmines on the enemy. Unfortunately, the aircraft did not participate in the battle.