Recoil energy. Initial speed and energy of the bullet, recoil of the weapon
Bodies act on each other with forces equal in magnitude and opposite in direction.
(Newton's third law).
None internal forces unable to change the total momentum of the system.
(One of the formulations of the law of conservation of momentum).
First, let's define the terms:
- Recoil is the backward movement of the weapon (barrel) during a shot. (Fundamentals of Small Arms Shooting).
- Rollback of small arms. Rollback (Unacceptable - recoil of small arms) - Movement of small arms under the influence of forces arising during a shot. (GOST 28653-90 Small arms. Terms and definitions)
- Recoil of small arms. Recoil. -- Forceful impact of small arms on the shooter, machine or installation as a result of a shot. (GOST 28653-90 Small arms. Terms and definitions).
As you can see, GOST separates the actual movement of the weapon and the force impact on the shooter, machine or installation. To simplify, I will use the term recoil in its established first meaning given in “Fundamentals of Shooting...”.
Recoil parameters.
Recoil is characterized by several parameters:
- Pulse.
- Energy.
- Strength.
- Power.
1. Recoil impulse.
By virtue of Newton's third law, two bodies interacting with each other acquire impulses equal in magnitude and opposite in direction. Numerically, the impulse of the force is equal to p=Ft, where p is the impulse, F is the force, t is the interaction time. Also, the momentum of the body is equal to p=mv, where m is the mass of the body, v is the speed. With the impulse of a shot, everything is a little more complicated, because... Not only a bullet, but also powder gases fly out of the barrel, so the recoil impulse is calculated using the empirical formula
where m is the mass of the bullet, v0 is the initial speed of the bullet, w is the mass of the powder charge, g is the acceleration of gravity, necessary for converting from the SI system to the technical system of units (from H*s to kgf*s).
According to the law of conservation of momentum (LCM), the total momentum of a closed system (not interacting with external bodies) is a constant. Those. no automation can change the momentum of a weapon that it received as a result of a shot. The only way to influence the recoil impulse is to influence the powder gases using, for example, a DTK.
2. Recoil energy.
It's no secret that shooting the same cartridge from a heavier weapon is more comfortable. The reason for this is the recoil energy is numerically equal to , where p is recoil impulse, and M— weapon weight, g — acceleration of gravity. In the technical system of units, energy is measured in kilogram meters (kgm). Because The weight of the weapon is set and is a constant value, within the manufacturing tolerance, then according to the same ZSI, no automation can change the recoil energy of the weapon.
3. Recoil force.
Once again let's return to the momentum formula p=Ft, p=const, but we have a value that we can influence - this is the interaction time t. Then, according to the same FSI, by increasing the interaction time by 10 times, we will reduce the recoil force by the same 10 times. . This effect has long been used in artillery, when the connection between the gun barrel and the carriage is carried out through a recoil brake. The time of the shot is calculated in thousandths of a second during this time the barrel with the bolt receives a recoil impulse, but the impact, through the recoil brake, of the barrel on the carriage is a couple of orders of magnitude longer, respectively, and the force of influence on the carriage is the same number of times less.
4. Recoil power.
Relationship between recoil and automation
Recoil is associated only with that automation that is activated directly by recoil. This is a free and semi-free shutter, recoil of the barrel with a short or long stroke, etc. Standing apart are systems that do not have automation at all or that have automation not related to recoil:
- A typical example of the first case is a three-ruler. It has no automation at all, however, there is quite a return, surprisingly for some people who believe that the return is only when the automation is working.
- Systems with automatic gas release and rigid locking of the barrel. The most common case in individual infantry small arms — automatically. The automation there is driven by a gas engine, regardless of recoil.
The influence of recoil and automation on the accuracy of automatic fire.
First we need to talk about the correctness of the comparison. returns various types of weapons.
It is correct to compare two samples in terms of recoil impulse only with approximately equal masses and automation schemes. For example, AKM, AK74, M16, G36 have a similar mass and a gas outlet with rigid locking, and their comparison in terms of recoil impulse will be correct. At the same time, it is correct to compare a machine gun and a light machine gun chambered for the same cartridge based on recoil energy, because with an equal or greater (for a machine gun) impulse, the recoil energy of the machine gun will be less than that of a machine gun due to the greater mass of the machine gun. Also, do not forget about the presence of various muzzle devices that can both reduce recoil (muzzle brake), prevent the barrel from moving away from the firing line (compensator), and increase recoil (recoil amplifier). And finally, the most correct comparison in terms of recoil power; this is the only way to fairly objectively compare a weapon with a gas outlet with rigid locking and a weapon with recoil of the barrel during a long stroke or a gas outlet with braking of the recoil of the firing unit.
Features of dispersion during automatic fire
Classic picture from the manual...
The peculiarity of dispersion when firing with automatic fire, especially from low-stable and unstable positions, is that the main cause of dispersion is recoil and, to some extent, the influence of automation.
Let's take a closer look at the process:
- The weapon is aimed at the target, the trigger is pulled and the first shot of the burst follows.
- The bullet flies out of the barrel and the resulting recoil impulse begins to deflect the barrel of the machine gun to the right and upward, while the bolt frame is released and accelerated.
- Gases accelerating the bolt frame, according to Newton's third law, act not only on the piston, but also on the front wall of the gas chamber. They not only push the frame back, but with the same force the body of the machine gun forward, trying to turn the barrel down.
- The bolt carrier with the bolt comes to the rearmost position and strikes the buttplate of the receiver, trying to deflect the barrel upward.
- The bolt carrier delivers the cartridge and strikes in the forward position, further deflecting the barrel.
- Finally the second shot follows and the whole story repeats itself.
The illustration shows graphs of the dependence of the area of the dispersion core on the recoil impulse.
In 1964 A.S. Neugodov carried out work to determine the dependence of the dispersion of automatic fire on the recoil impulse. Experiments have shown that as the recoil momentum decreases, the dispersion area also decreases, i.e. when firing a 7.62x39 cartridge, the main disturbing factor is recoil, but as the recoil impulse decreases, the contribution of the automatic system increases (more precisely, the contribution of recoil significantly decreases). This is confirmed by the fact that assault rifles with balanced automatics chambered for a low-pulse cartridge have an accuracy 2-3 times better than that of the AK74, and an assault rifle with balanced automatics chambered for a 7.62-mm cartridge tested in the 70s did not show any particular differences from the AKM . The recoil impulse of the 7.62 mm cartridge defeated all the efforts of the balanced automatic.
A short digression about balanced automation. It is widely believed that balanced automatics reduce/compensate or otherwise affect recoil. This is wrong. This automation is not driven by recoil, but by a gas engine and for this reason alone cannot influence it in any way. It’s just that when firing, the powder gases do not put pressure on the front wall of the gas chamber (there is no wall), but on the piston of the moving countermass, which is why the operation of the automation has minimal impact on the body of the weapon, and the impacts of the frame and the countermass occur simultaneously in opposite directions and are mutually neutralized. When fired, recoil acts on the bolt, and through it on the body of the weapon, and the time of its impact is determined by the time of the shot; the weapon receives a recoil impulse long before the automation starts working.
Rate of fire and why a fire monitor was needed.
As already written above, the main reason for dispersion during automatic fire is recoil and automatic operation. But the rate of fire affects the magnitude of this dispersion. At a rate of 600 rpm, 0.1 s passes between two shots, on the one hand this is very little (the rate is high), on the other hand it is a lot (the rate is small). Let's consider both cases.
- The pace is great. 1 tenth of a second is too small for the shooter to have time to react and return the barrel to a position close to the original one. This is clearly visible in the first illustration; the shooter only manages to bring the machine gun closer to its original position by the 4th shot, and the dispersion of the bullets is large. Reducing the speed by 3-4 times is not an option; this means a decrease in the speed of moving parts and is fraught with a strong decrease in reliability. In addition, when shooting at a target moving across the firing line, it can simply slip between the bullets of the burst due to the low rate of fire.
- The pace is slow. 1 tenth of a second is too large and the weapon has time to deviate significantly from its original position before the next shot. If you increase the rate of fire, this will allow you to fire a short burst before the weapon has time to deviate significantly from the aiming point. Increasing the rate of fire requires making the weapon more complex, at least introducing a cutoff.
- For balanced automatics 4000-6000 rpm.
- For a fire monitor circuit, ~2000 rpm for a two-bullet burst and 3000 rpm for a three-bullet burst.
- For classical percussion automatics, even an ultra-high rate of fire of 6000 rpm or more will not lead to the required improvement in accuracy due to high speeds of moving parts and strong impacts in extreme positions, which will lead to increased dispersion and breakdowns.
Looking at the required pace, it becomes clear why the fire monitor scheme achieved success. It simply has the lowest required rate of fire, which immediately makes it easier to ensure the survivability of parts. Why is it enough for the fire monitor circuit to have a rate two or three times lower, in contrast to other automation circuits? And here it’s worth returning to the beginning of the conversation about recoil, and specifically to such a parameter as recoil power. The peculiarity of the monitor circuit is that the shooter perceives the recoil not directly as in a conventional circuit or in a balanced automatic, but through a shock absorber spring that slows down the rolling unit. In weapons with conventional or balanced automatics, the time of transmission of the recoil impulse is determined by the shot time, on the order of several thousandths of a second, while in a fire monitor system the time is determined by the recoil braking time t = 1/30 of a second, which is 10-15 times longer and, accordingly, the strength and power of the recoil 10-15 times less. Because of this, the deflection speed of the weapon is much less and therefore a rate of 1800-2000 rpm is enough to fire a second shot as long as the deflection is small.
In the entire history of the Abakan competition, it was the balanced automation that was the lagging behind. Even for classic strike automatic weapons, it was possible to circumvent the problems with an ultra-high rate of fire. The creation of the AO-63 double-barreled assault rifle made it possible to have a two-bullet burst rate of 6000 rpm and at the same time maintain the normal speed of the moving parts of the automation. Moreover, the AO-63 showed accuracy records from all firing positions.
Scepter 06-02-2004 22:48
I read on the forum about recoil from different calibers, pistols, etc. And from the same pistol, of a certain caliber, which do you think describes the recoil more correctly, energy or momentum?
In fact, when a shot is fired, the hand is affected by the recoil force, which makes it move - FORCE. F=m*a - since acceleration is speed to the first power. If we assume (as the overwhelming number of sources, at least on the Internet) that the return is described by energy, Ek=mv2/2, then here we are considering the speed squared.
So, based on the above, the question is the following: in your opinion, does the bullet speed affect the recoil force (from one pistol of the same caliber) to the first power or to the square?
Doggy 06-02-2004 22:57
Theoretically, recoil when two bodies are repelled is calculated through an impulse... but recoil is transmitted in a pistol in two stages... the first directly... while the barrel is engaged with the bolt and the second through the return spring when the bolt goes back.
filin 06-02-2004 23:11
As far as I know, no one has really studied recoil as a phenomenon in our country. I only know that cartridges from the same batch give different results. subjective feeling recoil when firing from different pistols of the same type. Why - guess for yourself.
Mikhail HORNET 07-02-2004 12:30
impulse, of course.
Springs, etc. - they only stretch the moment of force, which, however, objectively reduces the recoil FORCE, but the impulse does not change.
BMD 07-02-2004 01:27
Guys, enlighten the dark - what the hell difference does it make for the user? And then, I don’t agree with Mikhail - the elasticity of the spring leads to absorption kinetic energy and decrease in impulse.
Mikhail HORNET 07-02-2004 07:49
the spring cannot in any way affect the impulse, the formula of which is known and cannot be adjusted in any way, but it can extend time and reduce/redistribute the moment of force acting on the shooter.
Humanoid 07-02-2004 08:00
The impulse cannot be reduced, it can only be extended in time. Which is what the spring does. Or rubber butt pads. The work of mechanics requires recoil energy, but not its impulse. mv = Ft, from here it can be seen that as the exposure time increases, its strength decreases. If you extinguish the recoil energy with the waste of powder gases (recoilless rifles, muzzle brakes...) then this is a completely different story.
Alex9x19 07-02-2004 09:03
impulse, of course.
m bullets * V bullets + m gases * V gases = m weapons * V weapons.
Springs, etc. - they only stretch the moment of force, which, however, objectively reduces the recoil FORCE, but the impulse does not change.
That's right, recoil is an impulse.
Compare how a 308 wine and a 12 cal bullet delivers.
They have the same energy, but the impulse of 12 cal is one and a half times greater.
I installed a shock absorber from Hogue on my rem 870, where the spring stretches the impulse over time and turns it into a push versus a blow.
BMD 07-02-2004 11:10
quote: Originally posted by Mikhail HORNET:
the spring cannot in any way affect the impulse, the formula of which is known and cannot be adjusted in any way, but it can extend time and reduce/redistribute the moment of force acting on the shooter.
Alex9x19 07-02-2004 11:53
Kinetic energy - mv2\2, m-constant, the recoil phenomenon occurs in the extreme position of the bolt, when the spring is compressed, and part of the kinetic energy of the bolt is spent on this, the speed and, accordingly, the impulse have dropped. This is for a pistol, regarding a revolver or a bolt. Your formula I have no doubts.
It is clear that then the energy will return the accumulated energy, but this will not affect the recoil, since the movement goes in the opposite direction.
The recoil phenomenon begins before the shutter stops.
A return spring force of ~8 kg will act on the frame.
Watch the slow motion video, you can see it there, the barrel begins to rise before the bolt hits the frame.
Scepter 07-02-2004 18:44
I thought for such experiments on reloaded cartridges, it might be worth having the Ransom Rest, but it costs a lot. Does anyone have experience using it?
SONY 07-02-2004 19:15
Why is it more correct to calculate energy:
Let’s take a pistol weighing 1 kg and 2 kg (for example, two .357 Magnum revolvers), if the cartridges are the same, then the recoil impulse is the same (and always equal to the bullet impulse), but everyone knows that the heavier the weapon, the less recoil, and the impulse comes from the mass doesn't depend. The recoil energy turns out to be inversely proportional to the mass of the weapon; this is precisely the dependence we observe when shooting identical cartridges from pistols of different masses.
Of course, stretching out the recoil over time reduces its impact on the shooter, because recoil power decreases.
Note that what needs to be counted is NOT the ENERGY AND SPEED OF THE BULLET, BUT THE ENERGY AND SPEED OF THE WEAPON! The lighter the bullet, the less energy is transferred to the weapon (E bullets)/(E weapons)=(m weapons)/(m bullets), i.e. Light bullets give less recoil despite greater speed.
The relationship between recoil energy and bullet momentum (if a non-automatic weapon is used) has the form E=(P^2)/2M, where E is recoil energy, P is bullet momentum, M is weapon mass. In the case of automatic weapons, this formula is approximately fulfilled.
If we take a bullet that is 2 times lighter and assume that its speed will become 1.5 times higher, then the energy of the BULLET will increase by 12.5%, the momentum of the BULLET AND WEAPON will decrease by 25%, and the energy of the WEAPON will decrease by 43.75%. Those. Lighter bullets provide less energy and recoil.
Alex9x19 08-02-2004 12:01
quote: Originally posted by Scepter:
What difference does it make for the user? The difference is such that it is natural to want to achieve the lowest recoil with the greatest accuracy, since I am interested in the purely sporting side of shooting (though not IPSC), I want to look at the combination of bullet mass / its speed - powder charge, while reloading.
In fact, it would be interesting to know about the comparison of the recoil after a shot with a heavy bullet - 147 at a subsonic speed, I don’t know, 300 m/s or even less, and the recoil after a shot with a light bullet - 120, 115 for example, or even 95 at a much higher speed. Not only the recoil is interesting, but also the accuracy (at 25 m), of course, regardless of the shooter’s error, from a vice, for example.
Of course, the recoil will be higher from a shot with a high-speed bullet, but the question is by how much? If we take into account the impulse, then the speed appears in the first power and this is acceptable, but if the energy is squared there, and then the recoil when firing at a speed of over 400 m/s with light bullets will be very noticeable. In addition to practical experiments, it would be interesting to know the theoretical side of the matter.
I thought for such experiments on reloaded cartridges, it might be worth having the Ransom Rest, but it costs a lot. Does anyone have experience using it?
with equal impulses the recoil will be the same.
It is by bullet impulse (Power Factor) that Minor and Major are divided in IPSC to equalize participants in terms of recoil. However, the vast majority use light 115 gr bullets, the rest 124. It's about about bullets with a diameter of 9 mm of various calibers.
No one uses 147 grams. Same as 90. The most accurate bullet for all my barrels is 115 JHP. The least accurate is 90 gr.
old 08-02-2004 12:57
Energy is at the beginning. From it, for simplicity, we can take a derivative - impulse. ENERGY IS INITIAL. Work comes from it.
Humanoid 09-02-2004 06:19
I would like to note that the momentum of a weapon after a shot is GREATER than the momentum of a bullet. For it consists of the law of conservation against the momentum of the powder gases, and also, if it exists, the wad. In fact, it would be reasonable to ask the question - why is the enemy, who receives only the bullet’s impulse already extinguished by air resistance, hit, and not the shooter, who receives the entire impulse of the shot in full? Contact area? Does anyone want to experiment on themselves? Place an armor plate on your shoulder with an area equal to the area of the butt plate. And ask them to shoot there. I don’t think anyone is smart enough to do something like this. So the damaging factor of a bullet is energy. Another question is what do we feel more during recoil - the energy of the weapon or its momentum? The answer is simple - if we are thrown back, it is the impulse at work. If it gives a bruise, that’s already energy. These quantities are inextricably linked, but their actions are different. The fact is that impulse does not disappear anywhere, unlike energy. If kinetic energy can be converted into potential energy springs, into heat through elastic and inelastic deformations, then the impulse transferred to the shoulder by the butt will need to be completely extinguished with your feet, resting them on the mother earth. The energy of the weapon will precisely deform your shoulder. (or palms - for a short barrel)
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You have the right to remain silent.
Crown 09-02-2004 16:27
quote: Originally posted by BMD:
Guys, enlighten the dark - what the hell difference does it make for the user? And then, I don’t agree with Mikhail - the elasticity of the spring leads to the absorption of kinetic energy and a decrease in momentum.
Nope.
The law of conservation cannot be fooled.
The Universe is energy and each of us is an energy Entity, and has its own energy account in the Energy Bank of the Universe. This is the energy, the energetic force with which we wake up and create. We receive it constantly, through the channel of Acceptance - Return - during sleep, during play, during creativity, during all kinds of cosmic infusions that occur during round beautiful dates type 1:1; 2:2; 3:3; solstices, equinoxes, etc.. It is at this time that a very powerful infusion of energy occurs on the Planet and is an increase in our vitality.
Preserving and aligning the channel of Acceptance - Return is very important so that all this free energy remained at the end of the day in excess, i.e. if you have worked to zero or God forbid you become energy bankrupt and you have a lack of energy, this means that you will not be able to invest energy in either new projects or manifestation. There can be no creativity, you have worked to zero.
Why is this happening? Where do we put our energy? Now, of course, we can talk about those people who have surpluses, but I think that we are all basically accustomed to giving more than receiving. And so, when we give away our energy, it is very difficult to understand the whole mechanism of how this happens. But this is the most important thing - to understand! And then it will be easy and simple to track all moments of energy loss. And it is important to remember: everything we give should come back to us.
Now we are not talking about finances and financial opportunities, we are talking about energy incl. and monetary energy. As much as we give, so much energy should return. If the total amount of energy returned to you is less than what you gave, then you become energy bankrupt.
Let's imagine the energy bill in rubles. In the morning there are 5,000 rubles in your account, throughout the day you spent 10,000 rubles and by the end of the day you had a stable minus of 5,000 rubles. This means that you have become energy bankrupt. You don't have enough vitality vital energy. You cannot create or manifest anything in your reality, you cannot rejoice and cannot experience a feeling of happiness.
This can be expressed in long night and day sleep, and even when you wake up, you will have a sleepy, lethargic state and a complete lack of joy, delight, pleasure. Or it may manifest itself as a state of depression.
How do you and I give energy?
Many of us play such a habitual role of rescuers, and when we play this role, the role of a rescuer, we completely de-energize ourselves, because the people we have to save suck the energy out of us, getting stuck in their drama. We indulge their will, take part in their games and voluntarily give up our energy.
Why is this happening? Why do we start saving by helping people? There are a lot of such people, they come to us with their problems, trying to shift their problems onto us, tell us how bad they feel, but at the same time, no matter what you do, they don’t want to change and nothing happens in their lives.
There are two reasons. The first reason why we start helping is because we all want to be good, to earn the love and approval of another person.
The second reason is more serious. When we cannot cope with the pain that is within us, we try to relieve the pain of other people. Both are completely inappropriate, because if these energies do not return to you, at least in equal quantities (and even better, if more), then you become energetically bankrupt, this affects your standard of living, your vital energy, how you can function and act.
If you don’t feel harmony, joy, balance within yourself, then nothing good can happen in your reality, this is the first and second thing - you will have absolutely nothing more to give to people in the opposite direction.
Under what conditions does energy loss occur?
One of the reasons is that each of us owns a large number of things, we live in a material world and we have a lot of things. And maintaining all these things takes a lot of energy. That’s why all Masters recommend physically checking your luggage so that there are no unnecessary things in the apartment and other places. If you don’t use something for more than six months, it’s probably better to get rid of it. It has been verified in practice that those people who have a lot of junk in their apartments usually have problems with finances. There is stagnation of energy. If nothing goes away, nothing new comes.
Let’s not look far for an example, you are all sitting at the computer, so now please look at what you have stored on your computer, how many books are stored on your computer and at home that you once read and no longer use. It’s good if you give them to friends to read, but if they’ve been lying around for a year, two, three, you’ve all learned what they contain, you’re no longer interested in them, but they create stagnation of energy, which interferes with the harmonious flow of energy. You give nothing and thereby receive nothing.
The most important blockages, during which energy is written off from our energy accounts, are two human emotions or, one might say, qualities. The first is anger. When we experience uncontrollable anger or an outburst of aggression, we experience a powerful outflow of energy. Any Master must maintain harmony and be in a state of balance and peace. If an outburst of anger occurs, we give away a lot of energy, which is then very difficult to get back. The second is constantly judging someone. Condemnation happens multiple times. Condemnation is a person’s type of thinking, the level of development of his consciousness. If we constantly, even over trifles, discuss someone (even though we try to avoid this), then in the maximum case this is JUDGMENT. And this happens over and over again and causes a maximum outflow of your energy.
In this case, energy vampires are not needed, you yourself voluntarily, consciously or not, give up your energy, constantly being in some kind of judgment and discussion of people and what happened to someone and somehow. If you take part in judgment and condemnation, if you try to keep up with the affairs of all your friends, acquaintances and acquaintances of their acquaintances, you thereby overwhelm yourself with information and create a blockage for the free and harmonious flow of energy.
It is very important to align and balance the channels of Receiving and Delivering energy. The most powerful channel alignment tool is gratitude. The real gratitude we feel. The word thank you does not refer to the energetic form of gratitude.
Gratitude comes in second place in its power, after Love. If you experience a feeling of gratitude, there can be no distortion in the flows of Acceptance and Bestowal.
Our physical body stores very little energy. We pass all the energy through ourselves and depending on how clean our channels are, how little distortion there is in us and how often we experience a feeling of gratitude, the more energy we can pass through ourselves and then even more of it will return to us.
If we want it to be financial abundance, it will be financial abundance.
All of us, Lightworkers, are the Vanguard of New Laws and New Energies and it is not proper for us to pat each other on the head,
proclaiming spiritual and material poverty.
You and I are prosperous Masters of New Energies and, going through activation after activation, you leave the energy signature of the Master on your subtle bodies, which everyone can see. If after this you continue to be in the energy of anger, condemnation, pity, you receive energy “arrivals”. And this happens for the good of your Soul, in order to lead you onto the Path of the Master finally and irrevocably.
I wish every Lightworker to live the conscious and abundant life of a New Life Weaver.
In Love and Service Lyudmila Anikina
In this article, I deliberately refuse any profanity, abstruse terms and other pompous words. That is why the text contains various inaccuracies and formal errors. But there will be no vectors, derivatives, integrals and other boring science here.
In theory, at school we learned Newton's laws and, at the same time, conclusions from them. Remember action equals reaction? m1a1=m2a2 (minuses omitted), where m is mass, a ˜ is acceleration. This implies the law of conservation of momentum (momentum). Let us recall what momentum is: a vector physical quantity that is a measure of the mechanical motion of a body.
In classical mechanics, the momentum of a body is equal to the product of the mass m of this body and its speed v, the direction of the momentum coincides with the direction of the velocity vector. p=mv. And the law looks like this: In a closed system, the vector sum of the impulses of all bodies included in the system remains constant for any interactions of the bodies of this system with each other. This is one of the interpretations.
Now let's remember the laws of jet propulsion. They directly follow the law of conservation of momentum: MrocketVrocket = MgasVgas, where Mrocket, Vrocket are the mass and speed of the rocket, and Mgas, Vgas are the mass and speed of the gases emanating from the rocket. This is how we get momentum, calculate the force of interaction, and the acceleration of the rocket. For some reason, “great specialists” do not appear who declare with aplomb that the speed of a rocket should be calculated not through the impulse “MgasVgas” of reactive gases or the repulsive force, but through their energy (MgasVgas²/2). Well, I haven’t met such “specialists”.
But there are countless “experts” who judge the recoil of a firearm by the muzzle energy of the bullet. It often turns out that SUDDENLY the recoil energy of the weapon is equal to the muzzle energy of the bullet. Why the weapon does not kill the shooter is unclear.
Let's consider a spherical vacuum example. So, in a vacuum under conditions of weightlessness there is a motionless (yes, in the accepted inertial coordinate system, blah, blah, blah - there will be no more matan) “spherical pistol” TT with a mass of 0.91 kg. And so he fires a “spherical bullet” weighing 0.0055 kg (5.5 g) at a speed of 480 m/s. For simplicity, we will assume that this is an elastic interaction. We are neglecting all sorts of bullet rotations and other things for now.
So the “spherical TT” threw the spherical bullet away from itself. According to the law of conservation of momentum, MpistVpist = MpuliVpuli. From: Vpist= MpuliVpuli/Mpist=0.055*480/.091=2.9 m/s. That is, after expansion, the “spherical TT” will move at a speed of only 2.9 m/s.
Let's take and calculate their energies after flying apart:
Epules=0.0055*480²/2=633.6J.
Epist=0.91*2.9²/2=3.82J.
Dearest! How so!! The pistol has 165 times less energy!!! Maybe that’s why, when fired, the gun doesn’t kill the shooter as it flies away?
But excuse me, you say, what about the law of conservation of energy? Where does it come from, this energy? Is this not the transformation of the thermal energy of burning powder gases into the mechanical energy of a bullet? But in fact, a firearm is an inertial internal combustion engine. He just moves the bullet for the most part. And its efficiency is usually very so-so.
Let's get to the point. Any, absolutely any source that describes recoil formulaically operates not with the energy of the bullet, but with its momentum! In order to be convinced of this, it doesn’t take much: run the queries “weapon recoil”, “weapon recoil impulse”, “weapon recoil force”, “weapon recoil energy” into a search engine. Wherever there are formulas (including descriptive ones), they operate not with the muzzle energy of a bullet, but with its impulse. Try to refute it. Formulaically.
Everything would be fine, but in addition to the bullet, the weapon is repelled by the high-temperature powder gases emanating from the barrel. Just reactive power, that's right.
Therefore, the total momentum of the weapon flying back is calculated as:
MweaponsVweapons=MbulletsVbullets+MgasesVgases.
Naturally, the recoil impulse will be greater than the bullet impulse. But it is extremely difficult to assess the influence of powder gases. Their speed is very high (up to 2000 m/s), but they have little mass and the process of leaving the barrel is difficult to take into account. There are a number of empirical formulas for calculating the recoil impulse of a cartridge. Yes, exactly the recoil impulse of the cartridge. It consists of the recoil impulse of the bullet and the recoil impulse of the powder gases. I use Blagonravov’s EMNIP formula, widespread in the Soviet school:
Io=mc*(1+(mp/mc)*(1275/V))*V, where:
M - weapon mass
mc - bullet mass
mp - mass of gunpowder
V - bullet speed
The empirical kit 1275 varies a little depending on the bullet speed, but that’s not the point. Read: Babak F.K. “Fundamentals of small arms” (Article 43) or Kirillov V.M., Sabelnikov V.M. Small arms cartridges.
The theoretical recoil energy is obtained by finding the recoil speed (dividing the recoil impulse of the cartridge by the mass of the weapon) and then the banal WeaponVoruzh²/2. And we get from several J to several tens of J. For example, in the notorious TT the powder weight is 0.00052 kg (0.52 g), hence the recoil impulse of the cartridge is 3.3 kg * m/s, and the recoil energy of the pistol is 5.98 J. Theoretically. Everything is different in life.
The weapon is held by the shooter, which means additional mass is added to the weapon. The movement of the weapon from recoil is dampened by the shooter's body. Recoil can be “smeared” by movement of the weapon’s mechanics. DT or DTK can be used, in which the weapon is braked by the reactive action of gases. The maximum recoil force depends on the bullet's release pressure, etc.
For comparison, let’s calculate the characteristics of a couple of cartridges (according to one of the options):
9x19Pair: 8g, 360m/s, 0.4g of gunpowder: 518J, 3.39kg*m/s.
5.7x28: 2g, 716m/s, 0.5g of gunpowder: 513J, 2.07kg*m/s.
The muzzle energy of the bullet is almost the same, but the impulse is different.
By the way, as an independent work, I suggest you think about why the 5.56x45 and 5.45x39 cartridges are called low-energy rather than low-pulse cartridges. Why do smart guys involved in weapons development use such terminology?
We are primarily interested in the conclusions:
The muzzle energy of a bullet is not a criterion for the recoil of a weapon.
Given equal muzzle energy, a cartridge with a heavier and slower bullet will always produce greater recoil.
It is convenient to use the recoil impulse of a cartridge only for assessing the recoil of a weapon and comparing cartridges, and not for calculating its exact value.
The use of recoil energy from a barrel that is movable relative to the weapon is one of the oldest and most successful principles for constructing automatic small arms. In more than a century since the appearance of the first such systems in the world, a wide range of weapons with a movable barrel have been produced - from compact pistols to machine guns and automatic cannons.
However, it should be noted that there are significant gaps in this spectrum. In particular, only a very small number of models of hand-held long-barreled weapons with such automatic equipment (smoothbore guns and especially rifles) achieved any noticeable success. We will briefly discuss why this happened below.
Recoil is a fundamental property of any throwing weapon, stemming from Newton’s third law, which states that any mechanical action causes a reaction equal in magnitude but oppositely directed.
Hiram Maxim's patent for his first self-loading carbine using recoil energy
Hugo Borchardt's patent for a pistol with a movable barrel, put into mass production in 1893
In our case, this means that throwing a bullet or other projectile by the force of expanding gases leads to the fact that the throwing weapon receives a momentum of motion equal to the total impulse of the projectile (bullet) and the powder gases leaving the barrel, but directed in the opposite direction. It is this impulse that forms the recoil - the movement of the weapon in the direction opposite to the direction of the shot. In the case of a weapon with a fixed barrel and a rigid locking of the barrel, all this impulse from the barrel is transferred to the body of the weapon and through it to the hands or shoulder of the shooter or to the installation.
Cross-sectional view of the legendary Mauser C.96 pistol
John Browning's patent for a long-stroke rifle, on the basis of which the Remington model 8 production rifle was created
The first who managed to practically use the previously wasted recoil energy of a weapon to carry out its automatic reloading was the American inventor Hiram Maxim, who lived in Europe at that time. In 1883, he filed a patent application describing a conversion of the Winchester repeating carbine with a Henry brace and an under-barrel magazine.
Having added a spring-loaded butt plate to the carbine, Maxim connected this butt plate with a system of rods and levers with a shortened reloading lever located in front of the trigger guard, so that with each shot, the movement of the entire carbine back relative to the butt plate resting on the shooter’s shoulder caused automatic reloading of the weapon.
Soon this highly experienced self-loading carbine was followed by the first fully automatic machine gun of its own design, in which the barrel with its shank and the bolt connected to them by an articulated pair of levers were able to move under the influence of recoil inside the weapon box, stretching the return spring. This first machine gun was followed by others, and by the beginning of the twentieth century, Maxim machine guns had long become one of the most popular and successful weapons in their class.
The Colt model 1900 pistol was the first production sliding-barrel pistol designed by John Browning.
Colt model 1900 pistol partially disassembled
Soon other inventors followed Maxim. In 1893, Hugo Borchard created the first more or less commercially successful self-loading pistol with a moving barrel. Already on next year The Mauser company received a patent for its version of a self-loading pistol using the recoil energy of a movable barrel; in 1896, John Browning joined this glorious cohort with his first “pistol” patents.
By the beginning of the twentieth century various options automation systems that use the recoil of a moving barrel have firmly taken their place among the most successful designs of self-loading and automatic weapons.
It should be noted that the main competitor of automation systems with a moving barrel - a system using the pressure of gases removed from the barrel while the barrel is stationary - appeared almost simultaneously with the systems described here. However, for quite a long time, gas exhaust systems were noticeably less popular, and here’s why.
Browning's "Auto-5" smoothbore shotguns are probably the most popular hunting weapon with a moving barrel in the world.
John Browning poses in this photo with his M1917 machine gun, which, like the Maxim system, used a movable barrel and gave the Maxim systems the most serious competition
An early version of the Remington Model 8 long-stroke self-loading rifle
A page from a catalog from more than a century ago advertising Remington model 8 rifles
The earliest automatic weapon systems were created during the transition from black powder to smokeless powder; the internal ballistic properties of the new smokeless powders were still very poorly studied, and the gunpowders themselves could have very different characteristics on the development of pressure in the barrel during firing.
At the same time, systems with a movable barrel depended only on the total recoil impulse when fired, and therefore were much less sensitive to variations in the powder charge and projectile, provided that the total impulse received by the barrel at the time of the shot was within limits determined by the designer, often quite wide.
The main disadvantage of systems with a moving barrel was, as is usually the case, the source of its main advantages - that is, the moving barrel itself. In order to ensure the required reliability of the weapon in conditions of expansion of the barrel caused by heating, as well as accumulating carbon deposits or dust and dirt penetrating from outside, the barrel, of necessity, had to have some gaps at the interface with the stationary elements of the weapon. This inevitably led to a loss in accuracy and shooting accuracy compared to systems with a fixed barrel.
In addition, the movable barrel needed support at at least two points - at the breech and in the muzzle of the barrel, or, in extreme cases, near its middle. For this reason, most systems with a moving barrel had a casing that covered the barrel along its entire length (or at least to the front fulcrum), which inevitably increased the weight and cost of the weapon.
The M2NV heavy machine gun is another exceptionally successful example of a short-stroke system, designed by Browning in the early 1920s and still in service today.
Maxim machine gun in service with British colonial troops, 1895
As a result of the above, very few rifles with a moving barrel were produced in the world. The most successful (in terms of number of units produced) army model was probably the American Johnson system rifle model 1941 (Johnson M1941), produced in quantities of several tens of thousands of units.
The most popular commercial model of a rifle with a moving barrel was the American hunting rifle Remington model 8 and its development model 81. Between 1906 and 1950, about 140 thousand units of this rifle designed by the legendary John Browning were produced.
For comparison, gas-operated self-loading rifles and carbines were produced on both sides of the conflict during the Second World War alone, with a total circulation of more than 10 million units. The production of machine guns with a moving barrel (Maxim, Browning systems, German MG-34, MG-42 and others) during the same period also amounted to millions of units.
True, there was one exception here - a self-loading shotgun of the same Browning system, known as Auto-5, was produced in Belgium for almost 100 years, from 1902 to 1999, with a total production of over 2 million units. Additionally, over 800 thousand units of the licensed version of this system, the Remington model 11 shotguns, were produced in the United States. All other shotguns with a moving barrel ever created in the world could not even remotely repeat this success.
In the period after the Second World War, in connection with the development of both knowledge about the internal ballistics and dynamics of weapons, and the creation of more advanced gunpowders, the development of new machine gun systems with a moving barrel gradually began to fade away, giving way to simpler and easier-to-use systems with gas-operated automatics . True, a number of designs created before or during the Second World War still remain in service. First of all, these are the German MG-3 machine gun and the American Browning M2HB heavy machine gun.
The first model of a Maxim machine gun with a movable barrel
Johnson Model 1941 rifle, one of the few rolling-barrel military rifle systems produced in series
But pistols with a movable barrel are still produced all over the world in difficult-to-calculate quantities, which can most simply be described as “millions of pieces per year.” This is explained by the ease of use of this scheme when combining the functions of the automation engine and the locking unit in the barrel of the weapon.
The influence of the moving barrel on the accuracy of fire at typical “pistol” distances is very small, so systems with a moving barrel will remain the most suitable for use in powerful service and combat pistols for a considerable time.
Speaking about the technical aspects of systems with a moving barrel and its rigid locking at the moment of firing, it should be mentioned that all such systems, as a rule, are divided into two classes - “with a long barrel stroke” and “with a short barrel stroke”.
The German Mg.42 machine gun, one of the most popular and successful machine guns with a moving barrel, is still in service in many countries under the symbol Mg3
A Beretta APX pistol, partially disassembled to demonstrate the simplicity of design of modern sliding-barrel pistols
Diagram illustrating the general principles of operation of long-stroke systems
In systems with a short stroke of the barrel, the length of its rollback under the influence of recoil until the moment of disengagement with the bolt is, as a rule, significantly less than the length of the cartridge. Typically, for hand-held small arms, this length ranges from 0.5 cm to 3 cm, after which the barrel and bolt are disengaged, the barrel stops, and the bolt, under the influence of accumulated inertia, continues to move backward, removing and ejecting the spent cartridge case in recoil.
Then, during the recoil, the bolt sends a new cartridge into the barrel and, at the end of its path, again engages with the barrel for the next shot. In most long-barreled systems (for example, machine guns), the mass of the bolt, as a rule, is noticeably less than the mass of the barrel, so that most of the momentum accumulated during their joint initial recoil is “lost” uselessly when the barrel, after disengaging from the bolt, stops in the receiver.
In order to make good use of this “lost” impulse, many systems have introduced a so-called shutter accelerator. This mechanical device in the form of a lever or a pair of rollers interacts with the bolt and fixed structural elements of the weapon so as to transfer part of the impulse from the barrel to the bolt by accelerating the bolt relative to the barrel with associated braking of the barrel.
In pistols where the weight of the barrel and bolt are usually comparable, or even where the bolt is heavier than the barrel, such a design does not exist practical application. Almost the only serial pistol that had a lever-action accelerator in its design was created in the mid-1930s in Finland (Lahti m35) and had a relatively short and therefore lightweight bolt.
This elegant Roth-Haenel self-loading rifle, produced shortly before the First World War, had an automatic design by Karel Krnka with a long barrel stroke.
Another little-known example of a system with a moving barrel is the Walther No.1 shotgun, which had a lever locking system similar to the Makim or Luger systems, but lost outright to the Belgian Browning Auto-5 shotguns
Systems with a long barrel stroke are distinguished by the fact that in them the barrel, coupled with the bolt, together go through the full recoil path inside the receiver, while the length of this path is necessarily longer full length cartridge.
At the end of the recoil, the bolt is intercepted in the rear position by a special sear, and the barrel, under the action of its return spring, begins to move forward. In this case, the bolt is unlocked first, then the barrel, moving forward, “leaves” the spent cartridge case remaining on the mirror of the stationary bolt. Once the cartridge case is completely out of the chamber, it is ejected from the weapon.
When the barrel reaches its extreme forward position, it automatically turns off the sear holding the bolt, and the bolt, under the action of its spring, rushes forward, sending a new cartridge into the barrel and, at the end of the roll, again engaging with the barrel. Due to the large mass and long path of movement of the moving system, designs with a long barrel stroke, as a rule, have a low rate of fire, as well as a somewhat more complex design. Therefore, they are much less common than systems with a short barrel stroke.
Today, the most popular class of weapons using automatic weapons with a moving barrel are self-loading pistols
As we could see from this very brief overview, systems with a moving barrel have a number of undoubted advantages that determined their success, both in the early stages of creating automatic weapons and at the present time (though mainly only for self-loading pistols). The shortcomings of these systems have led to the fact that gas-operated automatics have now become the dominant design in long-barreled weapons, which we will discuss in the next article.
In the next article in the series you will learn about weapons that use the energy of powder gases removed from the barrel