Subject: Aircrafts heavier than air. flywheels. Aircraft. The development of military aviation. Civil Aviation.

3.1. Aircraft heavier than air

The first airplane model made its flight in 1647. Its developer was the Italian Burattini. This aircraft had four pairs of wings located along the fuselage and a tail unit. The two middle pairs were motionless, while the movement, according to the principle of an ornithoper, was carried out by means of springs installed on the front and rear pairs of wings.

Here it is necessary to say a few words about the flywheels. Flywheels are heavier-than-air aircraft in which the lifting force arises due to the flapping movements of the wings, like a bird's. Another name for these devices is ornithopers. There are flywheels with a drive due to the muscular strength of a person (muscles) and with a mechanical drive from engines various types: spring, steam, internal combustion engines, etc.

Subsequently, up to 1809, various aircraft projects were created, but the matter did not reach their practical implementation. The founder of the scientific stage in the development of aircraft construction is called the Englishman D. Cayley. His experiments on a rotary machine in 1804 were the first aerodynamic experiments, thanks to which it was possible to accurately determine the lift developed by a low aspect ratio wing at different speeds and angles of impact on it. When testing the glider model, it was possible to establish the values ​​of the lift coefficient, and in 1808 to determine the points of application of this force.

A year later, i.e. in 1809, Cayley created a full-sized flying machine with a seat for the pilot, a tail and additional flapping wings. Jogging with gusts of wind allowed him to rise into the air for only a few minutes.

Cayley's On Air Navigation was soon published, the first among other theoretical works on fixed-wing flight. The inventor, confident that the muscular strength of a person is not enough to rise into the air, paid great attention to the development of a caloric (use of hot air), a powder engine and an internal combustion engine running on liquid fuel.

The first proposals for the creation of aircraft in Russia date back to the 1860s. Inventor A.V. Ewald presented to the public a description of the “ideal aircraft design”, which included all the elements necessary for flight: an engine, a propeller, a streamlined shape that provides low drag, fragments to achieve stability and steering. Unfortunately, it has not been worked out in detail.

A.F. Mozhaisky said a special word in the field of aircraft construction. It is known that in 1877 he proposed to the War Ministry Russian Empire build an aircraft. The project he proposed spoke of a monoplane with one pulling and two pushing propellers, with

wing in the form of a plane of slight elongation. Despite financial difficulties, by 1883 a braced monoplane had been created with two steam engines and three propellers (one in front and two on the sides). The fuselage, which housed steam engines(in the bow and central parts), the boiler, oil tanks, instruments and crew seats, was a boat with a wooden frame and linen lining. The rectangular wooden wing of small elongation, made in the "gull" type (slightly arched with a bulge upwards), had a multi-spar structure and silk lining impregnated with varnish to ensure airtightness.

The load-bearing surfaces supported steel braces connected to the masts on the fuselage and to the landing gear. The tail unit consisted of two twisting rudders (Fig. 3.1.).

Rice. 3.1.- Aircraft designed by A.F. Mozhaisky

The plane took off after a long takeoff run on wooden rails. Newspaper notes of that time contain information about the test flight of Mozhaisky's monoplane, which ended in an accident.

An important milestone in the history of aircraft construction is the creation by the German Nikolaus Otto of a four-stroke gas internal combustion engine (1876), which led to a qualitative improvement in the characteristics of engines. A few years later, Otto's compatriot, G. Daimler, invented a gasoline-powered engine, which led many designers to think about the problem of using such engines in aircraft construction, especially since by the end of the 19th century, no one had the prospect of using internal combustion engines in aviation. raised doubts.

The Russian scientist K.E. Tsiolkovsky also spoke about this, who in 1894 published a project of a cantilever monoplane of the classical scheme with gasoline engine internal combustion, the material for which was to be aluminum.

In the 90s of the 19th century, for the first time, the idea arose of using a device on an aircraft that ensures automatic stability of the aircraft in the air when flying in a turbulent atmosphere. Attempts to use the pendulum as an autopilot showed its serious drawback - the presence of acceleration forces in flight led to disruption of its operation. And soon the pendulum was replaced by a gyroscopic automaton, which is a small rapidly rotating under the influence of electric current a disk mounted on axes in such a way that its plane always remains stationary relative to the projectile. It was not until the 1930s that he found a life in aviation.

By 1910, two directions had developed in aircraft construction: two-seat biplanes without a fuselage with a pusher propeller and an elevator located under the wing and single-seat monoplanes with a fuselage, tail

And pull screw. Each of these designs had its own advantages: biplanes were distinguished by their high carrying capacity and the best view for the pilot and passenger, they were often used as training machines, while high-speed monoplanes were more suitable for amateur pilots and athletes. Thus, there were prerequisites for the evolution of aircraft of both types, and for several decades there was a sharp struggle between mono- and biplanes.

IN that period, not only the general designs of aircraft were improved, but also individual systems: control devices, power plants, landing gear. The cockpits were unified: there were pedals connected to the rudder, and a lever that controls the elevator and ailerons. Thus, the pilot could fly the plane with one hand and feet, which was very important for military purposes (shooting, photographing the area and other tasks). The layout, which has become standard, is also used in modern aircraft. In the prewar years, wheeled and wheeled chassis. The most common types of propellers were propellers with solid wood blades and high efficiency for that time. The hull and wings were covered with wood or canvas, steel was used mainly in the chassis structure, wing and fuselage connecting nodes, braces and control wiring. Metal was rarely used as a structural material.

The most typical biplane design was the plane of the Wright brothers,

created by them on the basis of a glider (Fig. 3.2.). It was supplemented by a four-cylinder in-line water-cooled gasoline engine of its own design, with a power of 12 hp. The engine drove two pusher propellers rotating in opposite directions. The pilot controlled the warping of the wing by moving the hips, the levers located in front of him served to turn on the engine and control the elevator. The first flight took place on December 14

Rice. 3.2.- Aircraft designed by the Wright brothers

Further modernization of biplanes contributed to the improvement of their aerodynamic performance: they became quite stable, streamlined and were able to reach high speed. The carrying capacity of these aircraft has also increased. By the beginning of the First World War, fuselage biplanes were replaced by more promising two-winged aircraft (bimonoplanes) with a propeller located in front and a fully sheathed hull.

In the Russian Empire, the first home-made airplanes appeared in 1909. However, the development of domestic aircraft construction was slow for the simple reason that the Russian industry did not produce engines suitable for use on aircraft.

Over time, the government, assessing the potential homemade aircraft, became interested in the fate of the domestic aircraft industry. Appropriations were allocated for the construction of experimental machines. Soon, the flight of the Gakkel-3 machine took place, made in the form of a bimonoplane designed by engineer Yakov Gakkel. In 1911, the Gakkel-7 apparatus (Fig. 3.3.) with a powerful engine, aileron control, reinforced structure and increased payload capacity won the First Military Competition for aircraft created in the Russian Empire. This car was the only one that passed all the tests. In 1912, Gakkel-7 received the Big Gold Medal, thereby recognizing the merits of the Russian inventor.

Rice. 3.3.- Airplane "Gakkel-7"

Gakkel's work on the creation of a bimonoplane was continued by Igor Sikorsky. His C-6 plane, with a hull lined with thin, carefully polished and varnished wooden planks, acquired a streamlined shape. Thanks to this, the talented aircraft designer managed to set world speed records: with two passengers on board - 111 km / h, with five - 106 km / h. For two years, Sikorsky's airplanes have won prizes in military aircraft competitions, in no way inferior to the leading European models.

In the meantime, monoplanes in their purest form also received their development. In 1907, the talented French aviator and designer Louis Blériot began to create monoplanes. His aircraft were the first monoplanes with movable surfaces for lateral control: some of his models had rotary wingtips, others had movable rudders on the tail. These innovations allowed the aviator to become the first pilot in the world to master monoplane maneuvering.

His historic flight across the English Channel on July 25, 1909 made his Blériot the most popular model. Since that moment, mankind has ceased to look at the aircraft as a means of entertainment for the public and turned it into one of the most promising species vehicles designed to transport people, goods and conduct combat operations.

An important step towards the improvement of the monoplane was the implemented project of the Frenchman E. Nieuport, which was based on the Blériot-11. Its durable, stable in flight, sensitive to steering deviation and well-planned, the Nieuport-4 soon took its rightful place in the armed forces of France, Russia and Italy.

In 1912, the designer and head of the aviation company A. Duperdussen for the first time used a monocoque design in aircraft construction. The airplane named after him had wood skin that was pressure-glued onto a blank in the shape of a fuselage. After removing the blank, the wooden shell was glued on the outside and inside with a cloth, and then varnished. The case obtained as a result of this procedure with a wall thickness of 4.5-5 mm was distinguished by great rigidity and strength.

Now the designers faced the task of increasing the carrying capacity of aircraft. It was possible to increase it only by increasing the take-off weight, which required an increase in the power of the power plant. And since at that

At that time there were no strong engines, it was supposed to put several engines on the planes.

Indicative in this regard was the creation in Russia of the Grand (Russian Knight) and Ilya Muromets airplanes, the projects of which belonged to Igor Sikorsky. Models had four engines installed on the wing. In front of the fuselage of the Russian Knight there was a glazed cockpit with compartments for the pilot, passengers, a toilet and room for spare parts and tools. There was a small space in front of the cockpit where one could go during the flight. When any of the tandem engines was stopped, the aircraft could continue its flight without hindrance (Fig. 3.4.).

Rice. 3.4.- Aircraft "Grand" ("Russian Knight")

The aircraft "Ilya Muromets", built in October 1913, became the successor to the "Grand". It was a biplane with a strong fuselage, in the bow of which there was a glazed cockpit with electric lighting and heating (Fig. 3.5.). The first time a biplane took off on December 23, 1913. Experiments with two engines turned off and take-offs on skis from the snow turned out to be very successful. World records for carrying capacity, range and flight altitude were set.

Rice. 3.5.- Aircraft "Ilya Muromets"

A person had the opportunity to observe and study free-flying "apparatuses" long before the creation of the first aircraft - he always had an example of a flying bird before his eyes. In the legends of any nation can be found fairy tale hero capable of moving through the air, and these methods are extremely diverse.

The ideas about the mechanism of bird flight were just as diverse. It has even been suggested that the lift force of the wing is caused by electric charges arising on loose feathers when the bird opens its wings.

However, heavier-than-air flight became possible quite recently (by the standards of human history) and more than a hundred years after the first flight on hot-air balloon(aerostat) Montgolfier brothers.

Gliders, or non-powered aircraft

Observations of soaring birds led to experiments using updrafts and the creation gliders. However, a serious disadvantage of a glider as a vehicle is that it is not capable of taking off on its own.

In 1891, Otto Lilienthal made a glider from wicker covered with fabric. For the period from 1891 to 1896, he made up to 2000 flights. August 9, 1896 Otto Lilienthal died. A copy of his apparatus can be seen in the museum of N. E. Zhukovsky in Moscow on the street. Radio.

Gliding was popular in the 1930s. Most of the well-known aircraft designers, for example, O.K. Antonov, S.P. Korolev, A.S. Yakovlev, started with glider projects. Application modern materials and aerodynamic forms has led to the fact that in conditions of stable updrafts, for example, in mountainous areas, gliders are able to make many hours and even many days of flight.

The aerodynamic schemes of gliders became the basis for devices heavier than air, driven by the power of human muscles - "muscle planes", as well as other devices with low flight speed.

Descendants of gliders are "hang gliders" and "paragliders". Paragliding is currently extremely popular.

Reduced models of paragliders are used as sports equipment for towing mountain and water skiers. Such a device can be made independently even at home.

Attempts to create an aircraft capable of independently taking off, landing at a given point and taking off again from there ended in failure not only due to lack of knowledge, but also due to the lack of a suitable engine. Equally true is the statement that the advent of a new engine, lighter and more powerful or based on a different principle of creating a driving force, leads to a revolutionary breakthrough in the development of aviation.

The theoretical foundations for the flight of vehicles heavier than air were developed by N. E. Zhukovsky at the beginning of the 20th century. The necessary experimental data were obtained back in the 19th century by A.F. Mozhaisky, O. Lilienthal and others.

The device and design of aircraft

Chapter 1. General information about aircraft.

Aircraft are heavier than air.

Aircraft of this type include: airplanes, gliders, aircraft, shells, rockets, helicopters, gyroplanes, ornithopters.

An airplane is a heavier-than-air aircraft for flights in the atmosphere with the help of engines and a wing that is fixed relative to other parts of the apparatus (excluding aircraft with angle formation / excluding variable sweep wings). Fuel: kerosene and atmospheric air.

The reasons for the aircraft becoming the main means of transportation in the air:

1. Great speed

2. Large load capacity and reach

3. Reliability in operation

4. High maneuverability, stability and controllability

The main parts of the aircraft:

Fuselage

Plumage

Power plant (these are not only engines, but also automation elements, power systems and engine life)

Wing creates lift when the aircraft moves. Usually it is fixed on the fuselage, but for VTOL aircraft it rotates about the transverse axis. Roll rudders - ailerons and wing mechanization elements are installed on the wing, i.e. devices capable of increasing the carrying capacity and drag of the wing during takeoff, landing and maneuver (flaps, flaps, slats, etc.).

Fuselage serves to accommodate the crew, passengers, cargo and equipment.

Chassis designed to move the aircraft around the airfield and absorb the impact energy during landing. They are equipped with brakes. Chassis are retractable and non-retractable. The latter have more drag, but they are simpler in design and lighter.

Plumage serves to ensure the stability, controllability and balance of the aircraft; located behind the wing and consists of movable and fixed surfaces.

Fixed horizontal plumage - stabilizer, vertical - keel. An elevator is pivotally attached to the stabilizer, and a poisoning rudder is attached to the keel. If necessary, gas rudders can be used for control.

The power plant is used to create traction. It consists of aircraft engines, as well as systems and devices that ensure their operation and change in thrust.

Currently, the power plant uses:

TRD - turbojet engines

turbofan engines - bypass turbojet engines

TRDF - turbojet engines with an afterburner

TRDDF - bypass turbojet engines with an afterburner

TVD - turboprop engines

ramjet - ramjet engines

SPVRD - supersonic ramjet engines, or hybrid

Civil aviation: turbofan, turbofan, turbofan, turbofan

Military aviation: TRDF, TRDF

Local aviation: TVD

The operation of the engine is provided by the following systems: fuel, lubrication, air intake, gases, start, control and automatic control

Aircraft equipment consists of: instrumentation, radio and electrical equipment, anti-icing devices, high-altitude, airborne and special equipment.

Instrumentation:

1. Flight and navigation (variometers, compasses, speed indicators, autopilot).

2. Control over the operation of the engine (pressure gauges, thermometers, flow meters).

3. Auxiliary (ammeters, voltmeters).

Electrical equipment ensures the operation of instruments, controls and radio, engine starting systems, lighting systems.

Radio equipment is means of radio communication and radio navigation, radar equipment, automatic takeoff and landing systems.

High-altitude equipment ensures the safety and protection of a person in flight (air conditioning systems, oxygen supply).

The onboard equipment provides convenience for passengers.

Special equipment- Devices for placing and spraying chemicals for Agriculture, for transporting the sick and wounded, for loading and securing special bulky cargo, for aerial photography.

A glider is a non-powered aircraft heavier than air. The lifting force is created by a wing that is stationary relative to the body. The forward movement is created by the action of the component force of the weight. Takeoff is carried out with the help of rubber shock absorbers, a winch with a cable or a towing aircraft. Flight in calm layers of the atmosphere is carried out with a constant decrease at an angle to the horizon. Airframe characteristics:

1. Flight altitude - 14 km

2. Flight range - 1000 km

3. The rate of decline - 0.4-0.8 m / s

4. Flight speed - 80-100 km/h

5. Wingspan - 29 m

6. Wing extension - 20-36 m

Aircraft projectiles and rockets are unmanned aerial vehicles heavier than air. These include:

1. ballistic aircraft

2. rockets for launching artificial satellites

3. rockets to launch manned spacecraft

Helicopter (g (x) helicopter) - an aircraft heavier than air, in which lift and thrust are created by rotors rotating in a horizontal or almost horizontal plane. The rotors are driven by piston or jet engines through a gearbox and a vertical shaft. In jet helicopters, the propeller rotates from a jet engine or nozzles mounted on the propeller blades. Supplied to nozzles compressed air from the compressor. The lifting force is created without the translational movement of the helicopter. The main rotor replaces not only the wing of the helicopter, but also the puller, which allows the device to:

Move forward, backward and sideways

Ascend and descend at an angle to the horizon

Hanging motionless in the air

Rotate around a vertical axis

This is achieved by tilting the main rotor thrust in the direction of flight.

An important property of the screw: in the event of an engine failure, the ability to rotate under the influence of the oncoming air flow, i.e. perform gliding or parachute descent and landing.

Construct active elements of the helicopter:

1. Fuselage, landing gear, main rotor and controls

2. Instrumentation, radio and electrical equipment

3. Power plant with systems that ensure its operation

4. Transmission, which includes gearboxes, shafts, clutches, rotor brake

Vertical take-off and landing devices are either a combination of the properties of aircraft and helicopters, or they are aircraft in which lift during takeoff and landing is created using special jet engines called lift. In level flight, lift is generated by the wing, and thrust is generated by conventional engines, which are called main engines. The prospect of using such devices is determined economic indicators: more complex and expensive design should have high performance.

Autogyro - an aircraft heavier than air, in which the main bearing surface is the rotor, i.e. a rotor that rotates under the action of an oncoming air flow. The translational movement of the autogyro is carried out, unlike a helicopter, by a conventional propeller rotated by an engine. Disadvantages of gyroplanes:

1. Significantly inferior to aircraft in flight speed.

2. Cannot take off vertically and land vertically

Ornithopters are heavier-than-air aircraft in which lift and thrust are created by wings that move like the wings of a bird. It is difficult to reproduce such a movement. Therefore, it is very difficult to create such devices constructively, and therefore it is economically unprofitable.

Mikhail Vasilyevich made the first practical attempt in history to use the Archimedean propeller for air navigation. We must not forget that the screw at that time was not known even as a mover for sea ​​vessels. This discovery of his shows that Lomonosov correctly understood the laws of air resistance and found a force capable of supporting and propelling the apparatus in flight. It is especially interesting that Lomonosov, apparently trying to destroy the reactive moment, provided in his helicopter two propellers rotating in opposite directions.

Thus, our great compatriot, while developing scientific meteorology, at the same time laid the foundations of aerodynamics, which arose as a science only at the end of the 19th century.

LECTURE №2

Topic: Lighter-than-air aircraft. Unguided balloons. controlled balloons. Airships.

2.1. Aircraft lighter than air

Many historians believe that the era of aeronautics began with the experimental flights of the Montgolfier brothers (late 1700s), but as early as the 3rd century. BC e. The Greek mathematician Archimedes, who discovered the law that a body immersed in a liquid loses exactly as much weight as the liquid it displaces, realized that this principle applies to gases as well.

The first successful display of a balloon filled with warm air was performed by a Jesuit priest, Bartolomeo Lorenzo de Gusmao. This significant event took place in 1709 in the presence of the royal family of King John V of Portugal. The apparatus was a small paper shell filled with heated air obtained from the combustion of combustible material contained in an earthenware pot, which was placed in a wooden tray suspended from below.

Of great importance for the development of the idea of ​​an aircraft lighter than air was the discovery of the Englishman Henry Cavendish - in 1766 he managed to obtain "combustible air" ("phlogiston"), currently known as hydrogen.

The names of Etienne and Joseph Montgolfier are known to almost all fans of aeronautics. In 1783, they managed to make a balloon capable of lifting an adult (Fig. 2.1.). Its carrying capacity was about 205 kg. Having risen to a height of 305 m, this aircraft flew 915 m and sank to the ground. The diameter of the ball was 12 m. The fuel was gas obtained from burning pieces of paper, wood, straw under the neck of the shell, and the straw was wet. The brothers themselves could not explain why they burned the wet straw - they intuitively felt that it would be better that way. And the explanation for this phenomenon was found relatively recently. If the shell is filled not only with heated, but also with humidified air, then at the same temperature and lifting force, the volume of the balloon is significantly reduced. The first passengers were pets sheep, duck and

rooster. This flight took place on September 19, 1783 in the presence of the royal couple of Louis XVI. The first flight of the hot air balloon with people whose names were Francois Pilatre de Rozier and the Marquis d'Arlande had a very short duration - about 25 minutes. and took place on November 21, 1783, but it was they who became the first aeronauts in world history.

Rice. 2.1.- Balloon

IN In the 19th century, balloon flights took on an unprecedented scale. Those who could afford it flew for fun and thrills. Appeared the new kind sports - aeronautics, and records were set one after another. Finally, balloons were used by scientists for a wide variety of observations and experiments.

Since 1860, the new mode of transport has been actively used by the military, which was associated with the beginning of the American Civil War. By the way, this influenced the development of aeronautics, as three major discoveries based on the use of aerial technology were made - air mail, mobile hydrogen production plants and "barges" for transporting balloons.

IN 1861 the military first transmitted a telegraph message from a balloon to the ground. This forced us to reconsider the traditional channels of transmission of mail messages.

The search for more convenient ways to refuel balloons resulted in the invention of a mobile hydrogen production unit. The process of chemical production of hydrogen was based on the principle of the interaction of iron and dilute sulfuric acid. The installation made it possible to quickly refuel balloons, which increased the mobility of military operations; later, these installations began to be used in civil aviation.

The third innovation was the use of a coal barge, which made it possible to transport and tow balloons, both ready-made and damaged ones. In other words, other vehicles came to the service of aviation, and the process of integrating vehicles began. In the future, by the way, this innovation prompted the idea of ​​​​creating and using aircraft carriers.

2.2. balloons

The balloon consists of a ball made of dense rubberized fabric. The balloon is filled with air or hydrogen (in modern balloons also with helium), which is heated by an adjustable burner installed in the passenger basket (gondola). The basket is attached to the ball with cables (Fig. 2.2.).

Rice. 2.2.- Aerostat

To extend the flight time, ballast was often used. Sandbags usually acted as it, hanging, as a rule, overboard of the basket, although - in emergency situations - these could be the most unusual things, or rather, the first thing that comes to hand.

Balloons more than once rescued the military. So, in the period from 1870 to 1871, they did a good service to the Parisians, who defended their city from the invasion of the Prussian troops. The besieged hastily built aircraft, which turned out to be an unusually convenient means of transporting people, urgent messages, supplies, and weapons. But one begets the other. For their part, it was during this campaign that the Prussian military began to use anti-aircraft guns that were specially designed for such air targets.

Bomb attacks were made from balloons. The first such attack was made in November 1944 by the Japanese during an attack on the United States. By the way, at the same time they used an original device that allowed the balloon to fly

with a constant height of almost 10,000 km above the Pacific Ocean. Each balloon carried a 15-kilogram fragmentation bomb and two incendiary projectiles. However, the "useful" effect of such weapons turned out to be extremely small: out of 9 thousand launched balloons, only one thousand reached the shores of America. 258 cases of bombing were registered (that is, a quarter of this thousand and 1 / 36 of the number of launched vehicles). 6 people died.

In general, balloons were used for a variety of purposes, including scientific ones. On July 11, 1897, three Swedish scientists led by Solomon August Andre undertook a research expedition to the Arctic in a 4531 m3 balloon equipped with sails. Unfortunately, the expedition ended tragically - the scientists died on Franz Josef Land.

But time passed, the technique improved and the records continued. On June 30, 1901, Professors Berson and Syuring rose in a balloon to a height of 10,800 m. next year he climbed already to 16,201 m. Three years later, the Americans Andersen and Stevenson reached a height of 22,066 m.

Do not lag behind foreign and domestic enthusiasts of aeronautics. In 1935, Zykov and Tropin stayed in the sky in a balloon for 91 hours and 15 minutes. This flight entered the list of world records. Impressive was the simultaneous launch of 25 balloons, which was carried out by domestic balloonists three years later.

In terms of size, the world's largest and fastest hot air balloon ever to take to the air is Tender and Colt's Virgin Otsuka Pacific Flyer, with a shell volume of 73,624 m3 and a height of 68 m. (this is the height of a 25-storey building). During a Pacific flight in 1991 maximum speed reached by the balloon was 385 km/h.

In a recent attempt world travel the balloon used a modern balloon "Endeavor" of the English company "Cameron Balloons". Unfortunately, due to bad weather conditions, this flight could not be completed in full.

And in October 1990, the head of the company, Donald Cameron, successfully flew with our compatriot Gennady Oparin from London to

THE USSR. The shell of the balloon itself was made of modern materials - Kevlar and carbon fiber. The preparation was thorough - parachutes, suits, walkie-talkies. At an altitude of 3 km, the travelers safely flew to Estonia, but then the wind rose to 14 m/s, visibility deteriorated sharply. I had to climb to a height of 5 km and descend in Latvia, where we landed on a potato field near Riga. And, if the frightened local farmers managed to calm down quickly, then it took quite a long time to deal with the KGB officers who arrived at night.

Summing up, it should be noted that balloons have become not only vehicle, but also a kind of symbol of our time. These devices were the first to fulfill the eternal dream of man to rise into the airspace.

1. Stones cannot fall from the sky, they have nowhere to come from! (Paris Academy of Meteorite Sciences, 1772)

2. In the future, computers will weigh no more than 1.5 tons. (Popular Mechanics magazine, 1949)

3. I think that in the world market we will find demand for five computers. (Thomas Watson - Director of IBM, 1943)

4. I traveled this country far and wide, talked with smartest people and I can vouch for you that data processing is just a fad that won't last more than a year. (Editor of Prentice Hall, 1957)

5. But, what... could be useful in this thing? (a question in a discussion of the creation of a microchip in the Advanced Computing Systems Division of IBM, 1968)

6. No one may need to have a computer in their home. (Ken Olson - Founder and President of Digital Equipment Corp., 1977)

7. A device such as a telephone has too many shortcomings to be considered as a means of communication. Therefore, I believe that this invention has no value. (from discussions at Western Union in 1876)

8. This wireless music box cannot have any commercial value. Who will pay for messages that are not intended for some private person? (Business partners of David Sarnov in response to his proposal to invest in the radio project, 1920)

9. The concept is interesting and well designed. But, in order for an idea to work, it must contain common sense. (Professor at Yale University in response to Fred Smith's proposal to organize a service fast delivery; Fred Smith will become the founder of the delivery service Federal Express Corp.)

11. Yes, who the hell cares about actors talking? (Warner Brothers reaction to the use of sound in cinema, 1927)

12. We don't like their sound and, in general, guitar quartets are yesterday. (Decca Recording Co., which turned down a Beatles album in 1962)

13. Aircraft heavier than air are not possible! (Lord Kelvin - physicist, president of the Royal Society, 1895)

14. Professor Goddard does not understand the relationship between action and reaction, he does not know that the reaction needs conditions more suitable than a vacuum.

It seems that the professor is experiencing an acute shortage of elementary knowledge, which is taught back in high school. (newspaper editorial New York Times, devoted to the revolutionary work of Robert Goddard on the subject of the creation of a rocket, 1921)

15. Drilling the earth in search of oil? Do you mean that you have to drill the ground in order to find oil? You are crazy. (response to a draft by Edwin Drake in 1859)

16. Airplanes are interesting toys, but they do not represent any military value. (Marshal Ferdinand Foch, professor of strategy at the French General Staff Academy)

17. Everything that could be invented has already been invented. (Charles Dewell - Commissioner of the US Patent Office, 1899)

18. Louis Pasteur's germ theory is a ridiculous fantasy. (Pierre Pacher - professor of psychology at the University of Toulouse, 1872)

19. The abdomen, chest and brain will always be closed to the intrusion of a wise and humane surgeon. (Sir John Erik Eriksen - British physician, appointed Surgeon General to Queen Victoria, 1873)

20. 640 kilobytes of memory should be enough for everyone. (Bill Gates, 1981)

21. $100 million is too high a price to pay for Microsoft. (IBM, 1982)