And bullets whistle

You can hear people a shot, if you shoot at him?

It all depends on what exactly the weapons and what ammunition is being fired. In General, ammunition for firearms are divided into two categories: subsonic and supersonic. In the first case the velocity of the bullet or projectile at the exit of the barrel exceeds the speed of sound, and the second exceeds. Accordingly, if the target is shooting subsonic ammo, the target first shot. If you shoot supersonic ammo, then to the goal first, the bullet fly, and then comes the sound of a gunshot. It’s simple.

Most modern firearms used for shooting supersonic ammo. For example, the initial velocity of the bullets SVD sniper rifle is 810 — 830 meters per second, the AK-74M is 900 meters per second, the projectile six-barrel aircraft cannon GAU-8/A Avenger assault aircraft A-10 Thunderbolt II — 1010 meters per second, gun 2A46M-2 main battle tank T-90 — 905 — 950 meters per second when firing armor-piercing shells and 1715 — 1800 meters per second when firing apcr shells, pistol Glock 17 — 375 meters per second, the CT — 420.

The speed of sound in air in normal conditions is 330 meters per second, but this setting changes with the changes in atmospheric pressure, air temperature and altitude.

In 2015, the American leading YouTube channel Lone Star Boars, made a few recordings of sounds of bullets of different caliber, hitting the target and flying past her. Shots were fired from the weapon installed on it devices silent flashless, to make the sound of the shot as quietly as possible. When firing supersonic ammunition at first was heard as the bullet hits the target, and then it comes the shock wave from the bullet and suppressed sound of a gunshot. If it misses, the goal “heard” the shock wave from the bullet after it passed.

With subsonic ammo, the pattern was inversed: first goal “heard” the whistle of a flying bullet for her, then the sound of a gunshot and after that, it got the projectile itself.

How does the silencer?

Before answering this question, we need to understand more of what formed the sound of the shot. If to speak simply, when firing the firing pin prick primer in the bottom liner (usually a small brass Cup filled with shock-sensitive explosives). After that, the charge in the primer is ignited and ignites the powder charge in the cartridge case, the result of burning powder gases which are formed. They push the bullet out of Dulce liner and push it along the bore. Accumulated during the motion along the trunk of the kinetic energy of the bullet is enough to cover some distance.

Now, the sound of a gunshot is composed of several sounds, but the largest contributions come from two of them. The first is the whistling or hissing of the powder gases intruding into the gap between the bullet and the wall of the bore when fired. Second — cotton, generated by the expanding powder gases at the moment when bullet exits from the barrel. This cotton is also referred to a muzzle wave. If the shooting is supersonic ammo, the sound of the shot still mixed and the shock wave from the bullets flying faster than the speed of sound. This shock wave is called ballistic.

All existing mufflers, which should be called with devices of silent flashless, designed to reduce the volume of the shot when firing subsonic ammunition. When shooting supersonic ammunition, the silencer, of course, will reduce the volume of the shot, but the cotton from flying faster than the speed of sound the bullet will still be clearly audible at a distance of just a couple hundred meters.

The muffler is a device fixed on the barrel of small arms (sometimes it is part of the design of this weapon), which should substantially weaken the sound of the shot and to hide the flame gases. Most of the mufflers is assembled from a cylindrical body fixed to the barrel and the inner insert forms a chamber. But design can be different. For example, there are silencers with complex shapes of gas-dynamic partitions, forward and collide the flows of powder gases.

When fired, the powder gases push the bullet along the bore, after which it enters the Central channel of the muffler, and then leaves it. Also the powder gases following the bullet, the silencer expand and fill the chamber. There they grow cold, a little decrease in volume and lose energy. Then following the bullet powder gases cooled with a significantly slower rate leaving the muffler. Thanks to the silencer cooled exhaust gases coming out of him, expand more slowly, and thus achieved a significant reduction in the volume of the shot.

In some models of attenuators is found in the phenomenon of the first cotton. The fact that the first shot of the camera device silent flashless filled with air. When fired, the powder charge in the cartridge case does not become completely burned, and part of the powder together with the powder gases following the bullet hits the muffler. In his chambers unburned powder burns, pressure builds up in the device. After the release of the bullet from the silencer the gases break out and produce a loud clap, often the volume is not inferior to shot without a silencer.

After the first shot all the cameras in the muffler is completely filled with the powder gases and oxygen content in them is very little and not enough to burn unburned gunpowder. For this reason, after the first shot, using a silencer POPs is not happening.

It should be noted that the vast majority of cases, the silencer, despite its name, removes the sound of the shot completely. The volume of shot modern firearms, depending on the design is from 130 to 180 decibels. For comparison, the volume of a police siren is about 140 decibels. Modern silencers can reduce the volume of shot at most 40 decibels. But there are exceptions.

It is technically possible to significantly reduce the volume of the shot, if the weapon, the silencer for it and the cartridges are designed as a single complex. A typical example is the VSS sniper complex, nicknamed “Vintorez”. It is a weapon used for shooting subsonic ammunition 9mm with a muzzle velocity of 280 — 295 meters per second. The barrel of a sniper rifle is made shorter than other rifles — just 200 millimetres and has a plurality of holes throughout its length.

Silencer “Vintorez” is put on the barrel of the rifle and becomes like him. When fired, a portion of the powder gases pushes the bullet partially out of the barrel through the holes and fall into the expansion chamber of the muffler. The remaining gases at the outlet of the barrel also fall into the muffler and come across a ring insert-penetratio. As a result inside of the muffler of the powder gases expand and cool, and their flows are redirected so that they faced each other and extinguished the energy of each other.

As a result, the volume of shot special sniper rifle VSS is 120-130 decibels. Designers managed so well to reduce the volume of shot rifle, when the shot was heard its automation. Actually, it was the clang of automatic rifles and it can be learned by sound. By the way, listen to the sounds of shooting from VSS and generally to determine whether you are able to know the weapons and military equipment by the sound of it, you can through our test, “what Is that machine?”.

Is it true that a weapon with a short barrel firing the loudest weapon with a long barrel?

Yes, but with many reservations. When using the same ammunition of the same caliber guns with different length of the barrel, the shot will be louder at that, whose trunk is shorter. However, the difference at the hearing to determine it will be extremely difficult, but measuring devices will show. The fact that the volume of the shot depends on many factors, chief among which are temperature pushes the bullet powder gases pressure. The longer the barrel, the less the temperature and the gas pressure, the quieter the shot.

For comparison. The volume of shot from a pistol a Glock 17 Gen. 4 that uses cartridges of caliber of 9×19 Parabellum, is 160 — 165 decibels. The length of the barrel of the gun is 114 millimeters. The CZ 75 pistol of the same caliber with the barrel length of 120 mm shot volume is about 160 decibels.

Why a shot from a railgun is accompanied by smoke, thunder, and sometimes flame?

The most famous development of railguns to 2018 was carried out in the interests of the U.S. Navy. Such weapons were developed by American company General Atomics, and British BAE Systems. It was planned to put into perspective the ships (e.g., destroyers of the “Elmo zumwalt”) instead of traditional artillery. It was assumed that the shots from railguns would be cheaper, more accurate and more devastating shots from conventional artillery. However, the projects were closed due to the technical complexity and cost of development.

Railgun is a weapon that uses electromagnetic acceleration of the projectile force. It a shell at the first stage of the shot is part of an electric circuit, moving between the two contact rails (hence the name gun). For the shot gun needs a short-term supply of high voltage and current, which could not provide simple connection to electrical network. To solve this problem, developers used Ionithermie Assembly.

On the video of the test railguns can be seen that, when fired from the barrel of a gun breaks the smoke (and sometimes flames), and the shot is accompanied by a loud explosion. Because of this, some enthusiasts even suggested that in the railgun, the initial acceleration of the projectile kinetic — metal blanks without explosives used powder charge. Supposedly, the projectile is pushed down the barrel of powder gases, after which the acceleration he is already attached to the electromagnetic forces. This theory is explained and the smoke and the flames and the roar of the shot.

It is actually a little easier. Energy shot of the prototype of the railgun developed by General Atomics, was 32 megajoules. At the time of firing the charge stored monitorname assemblies, almost instantaneously discharged onto the rails of the gun, resulting in them using a metal disc-the projectile passed an electric current of tremendous voltage and power. The current developers do not reveal. As a result of the discharge part of the metal on the rails was burnt up. In addition, the disc was partially covered with plastic and grease, which are also burned when fired. This explains the smoke and flames.

When fired, the initial velocity of the blanks is slightly more than Mach 5, that is, the projectile flies out of the barrel of the railgun to hypersonic speed. The loud sound of a shot of a railgun consists of two sounds: the shock wave from the pigs flying at hypersonic speed, and the expanding air compressed in the barrel by the moving projectile and pushes projectile thereby.

Why, when the assault aircraft A-10 Thunderbolt II firing of a gun, we hear two sounds of shots?

Americans are very proud of their assault aircraft A-10 Thunderbolt II. These aircraft went down in history as the aircraft built around a gun — samostalni GAU-8/A Avenger with a rotating unit trunks. This weapon has a high firing rate, which averages 3.9 thousand rounds per minute. When shooting it makes a special sound that the American military called brrrt. On many recordings you can clearly hear that when firing the A-10 issue dismuke brrrt — one loud and the other quiet.

This phenomenon has two different explanations, depending on exactly where the observer is. If the observer is near to the purpose for which the A-10 firing, he hears two sound shots. Initial velocity of the projectile when firing the GAU-8/A is 1010 meters per second, almost three times faster than the speed of sound. Shells fly to the target first, beat on it and these attacks first, and hears the observer. Then came to him directly the sound of gunfire from Avenger.

It is seen and heard, for example, the record with the joint tactical exercises of the air force and the US Army conducted in Nevada in the spring of 2019:

Here no less vivid example of two brrrt — shells hit the ground and the sound of the shot. In this video, the A-10 has a us military fire support from the air, probably in Syria:

The second case is dual brrrt occurs when the observer is on the side of the flight path A-10 to the goal. Then, the first sound he hears is the sound of the shots from air guns. And the second is the echo of that sound. It occurs when the muzzle wave reaches the earth, is reflected from it, and then reaches the observer. This phenomenon is most common in mountainous terrain. This phenomenon is well seen and heard in this video:

Leave a Reply

Your email address will not be published.