The phenomenon of the shot clearly traced the relationship and interaction of some elements, and other factors.
For example, the velocity of the projectile in the barrel depending on the pressure, but the pressure is dependent on the intensity of combustion of gunpowder and the volume zasnaryadnogo space, which in turn depends on the velocity of the projectile. In the study of the shot, all these factors are considered in relationship.
In the phenomenon of shots distinguish the following periods:
preliminary period – the composition of the capsule from the explosion before driving the upper edge of the column fractions or center of mass;
first or main – from the beginning of the movement until the end of the combustion of gunpowder; During this period, the gases make the most of the work.
The second period – adiabatic (without supply of energy) expand the already formed gases. Pressure falls to the muzzle, the speed reaches the muzzle.
Third period — the period of aftereffect of powder gases in the barrel and the projectile. At the end of this period the projectile at the muzzle already reaches the maximum speed. Period aftereffect on the barrel ends when the pressure at the bottom of the sleeve to about 2 bar. At this point, release rate reaches its maximum value.
Fires cap (HF): a very short impulse c pressures up to 60 bar, wad — the shock absorber is fully compressed, the gaps between the ‘grains are chosen due to rebuild and start strain, expanded polyethylene liner and pressed her to the chamber walls.
This gas under the influence of the increased volume of the chambers KV continue until the end pirostaticheskogo period will determine the density of loading.
According to the theory of combustion Belyaev-Zeldovich nitrocellulose gunpowder light up immediately, but with a delay time to transition from the solid propellant to gaseous state by heating gases HF, after which the entire surface of the powder throughout the volume of the chambers is ignited almost immediately.
Since the beginning of the motion wads and shot at rebuilding and deformation appears the force of inertia, under the wedging action occurs repeatedly shot and increases the frictional force of the projectile shot against the walls of the sleeve.
The upper limit of the projectile shot remains stationary. After moving inside the shell due to the rebuilding of the fraction and deformation, the force of inertia is reduced to almost zero. The shell is held in the sleeve by friction propped projectile shot.
When the pressure force exceeds the resistance of the powder gases friction forces, the entire shell will begin to move. Pressure according to this point, I suggest to consider speeding up the pressure in the shot fired.
The period from the beginning of the shot changes the pressure on the operation of HF prior to the movement of the entire projectile shot its center of mass is called pirostaticheskim or preliminary.
Duration pirostaticheskogo period 0.15 0.2 ms.
From this moment begins the first period shot vstrela.
Once again, the force of inertia becomes effective. It will increase with increasing pressure, the curve of change follows the shape of the pressure curve peaks at the same place and time.
Upon reaching the peak pressure is completely hung compression deformation of the fraction, then possible slight deformation of attrition against the walls of the barrel when containerless equipment. The height of the column fractions decreased by almost a quarter, according to Shteingol’d 22.4%.
Pressure increases. Speed fraction increases. At that moment, when the rate of gas generation will not provide growth of volume of gases, sufficient to compensate for the increase in zasnaryadnogo space, the pressure will peak and begin to decline.
At a distance of about 500 mm from the official cut-off at well-chosen performance conditions loading gunpowder burn completely and continue burning.
It is important that the burning was completed at a pressure of 150 bar, guaranteeing maximum conversion of chemical energy into heat powder.
The earlier stops burning, the greater will be the initial velocity and less muzzle pressure. The velocity of the projectile from the muzzle of 0.8-0.9.
It begins the second period of the shot the shot.
Further acceleration of the projectile is not the flow of energy. The projectile shot leaves the barrel. Nothing special in this period does not occur, the exception — Tapered Drill according to the type of the Triborough Fabarm.
Aftereffect period. The last period, referring to the internal ballistics.
In the trunk to choke off a fraction of the compressed layers of the column fractions. When all the projectile left the barrel of the traditional shot wad and obturator braked and do not affect the shot talus, defend a shot by a projectile expire jet propellant gases.
From the size and shape of the choke depends on quality indicators scree accuracy and uniformity, as well as the degree of deformation of the fraction.
In the absence of traditional wads choke leave the trunk at the same time the shot with a compact shell. At the same time expiring jet propellant gases continue to put pressure on the wad.
There is a slight increase in the velocity of the projectile as compared with muzzle. This fraction of the lower layer to the sides forming a uniform and broad scree shot. So coveted when shooting at short and medium distances.
When the process equipment container fraction leaves the barrel part of the container in the presence of the choke or fully therein in the barrel without choke.
In recent years, choke tubes of various forms of designs and sizes.
It is believed that they are performing a three-pronged challenge: relieve pressure before the shot shell;
pyzh- detain container trunk (some choke tubes are for this special teeth);
act as a muzzle brake compensator – redistribute the direction of the flowing stream of powder gases. Reduce the maximum speed of the impact, and the aftereffect of powder gases to the shot shell.
Period aftereffect for the projectile 20 – 40 caliber, the rate for this time increased by 0.2 – 2% over the muzzle.
Aftereffect period for guns — to reduce the pressure in the barrel up to 2 bar, with the speed and energy of the impact is increased compared with the muzzle due to the reactive power of powder gases. This explains why a significant difference in the rate of return under the same initial velocity and weight of the projectile, but on different propellants with different muzzle pressures.
(The theory of free recoil moving parts. Serebryakov on p. 371)
Toast (message) should be brief, as a shot. (A) The first pancake is always lumpy.
Special consideration deserves a shot all the periods, except for the second.
Always adhere to the principle that helps those who are working. I began.
For this reason, the article turned out great.
Ladies and gentlemen, you may proceed.
In the future, I plan to review each process separately shot.
Michael Bagdashkin24 March 2013 at 23:21