Modern War Weapons

A War of Technology

 

rendition of an anti-satellite weapon
rendition of an anti-satellite weapon

Ever since men fought wars using spears and bludgeoning weapons, the side with the most advanced tools had a major tactical advantage over the other. When more advanced weapons came into use, such as larger range projectile weapons like bow and arrows, the fighters with the more primitive tools were faced with an unsavory situation. Though much has changed since the primitive roots of mankind, little has changed at the same time. America understands the importance of leading the innovation in the field of military technology. We devote engineers and scientists to developing new technologies and refining existing ones. Modern war has reached a level of sophistication where modern science and technology are of highest importance on the battle field. As science progresses, new military technologies are derived from what we learn.

 

Weapons are of fundamental importance in the event of war because a robust arsenal provides a forceful advantage over the opponent both with defensive and offensive tactics. The more current the weapon, the stronger the advantage because a brand new weapon does not allow the opponent to have a prepared library of countermeasures to use against the weapons in our arsenal. Some weapons in modern times, such as kinetic energy weapons, still utilize the same physical concepts to inflict damage that have been used since the dawn of civilization. However, the years have also ushered in new classes of weapons to keep up with advancing technology, just as armor-piercing firearms were used to exploit the slow nature of the armored knight that had a defense designed for swords, not bullets. Today’s weapons can be partially broken down into kinetic energy weapons, anti-satellite weapons, and beam weapons.

KINETIC ENERGY WEAPONS

A kinetic energy weapon is one which uses physical movement to inflict damage. These include both projectile and explosive weapons. In physics, the equation that describes kinetic energy is as follows:

                                           KE = mv2/2                                      (1)

Here, m is mass, and v is velocity. The standard units for this equation are: kinetic energy in joules, velocity in meters per second, and mass in kilograms (unlike weight which is a

kinetic energy of projectiles is easy to calculate
kinetic energy of projectiles is easy to calculate

force, mass is independent of the strength of gravity). This simple equation has a tremendous range of applications. For a projectile, the kinetic energy can easily be found by plugging in the mass and velocity of the projectile. For explosives, things like shock waves also derive from this equation, though the math is too involved for the context of this document as it takes a dive into calculus. One important thing to realize about this equation though is that if the velocity of an object or particle is doubled, the energy it has quadruples.

If     V = 2v:

KE = (1/2)m*(V)2 = (1/2)m*22v2

 

 

GUNS

 

Guns utilize the fact that kinetic energy is proportional to the square of velocity. This is how a small, light-weight bullet can cause a surprising amount of damage. The most popular gun today is the AK-47, introduced in 1947 as the name suggests. However, a more current style automatic rifle has a different configuration, called bullpup. Unlike the

bullpup vs conventional configurations
bullpup vs conventional configurations

AK-47, the bullpup places the magazine behind the trigger, which allows the barrel to extend farther rearward, creating a shorter, more maneuverable weapon without sacrificing accuracy (Denny 63). The advantages of the bullpup configuration have made it a choice style gun for the American armed forces since its origin in the mid-1980s. Though the machine gun has come a long way since its debut in the 1880’s, the physics have not changed and engineers still face some of the same problems Hiram Maxim did in 1883 with his original machine gun (Denny 62).

 

One such problem is that of recoil. Isaac Newton’s third law of motion states that for every physical action, there must be an equal and opposite reaction. That means that even when a semi-truck hits a fly, the fly exerts a force on the truck in the opposite direction of the force that the truck exerts on the fly, slowing the truck down a miniscule amount. But when we talk about a bullet zooming faster than the speed of sound out of a barrel of a gun comparable in weight to the round, the opposing force, or recoil, pushing the gun back resulting from Newton’s third law is considerable. If automatic weapons did not have a system to lessen the effects of recoil, modern high-power automatic rifles that fire hundreds of rounds per minute at thousands of feet per second would be impossible to use. Additionally, if giant canons such as a howitzer gun did not have an ample recoil reduction system, it would be unreasonably difficult to control. With good recoil reduction, the size of the weapon able to be used by the soldier or vehicle can be dramatically increased.

 

With mobile guns, the recoil is dampened with springs and, with machine guns, some of the kinetic energy is ingeniously used to power the automation mechanisms.

 

 

 3D modeled M2 automatic rifle

 

Muzzle brakes are often added to further reduce recoil and also muzzle rise – the upward jerking motion of the gun as a result of recoil. Muzzle brakes are holes cut into the tip of a gun that redirects the expanding gas from the explosion in a way that reduces the kick. Recoil reduction in rifles reached a conclusion in 1963 with the recoilless rifle. It redirects some of the propellant gas from the explosion out the rear end of the weapon, using Newton’s third to counteract the momentum of the bullet exiting the barrel. Very little recoil allows for a lighter weapon, but the drawbacks to the recoilless rifle is that it is dangerous to use and requires significantly more propellant to function (Denny 73).

In larger artillery weapons such as cannons, recoil reduction is especially important because without a good system in place, the gun will need to be constantly re-aimed which is grossly time consuming for a behemoth weapon. Additionally, guns mounted onto vehicles and aircraft must not have too much recoil to damage what they are mounted on. An improved dampening system increases the power limit of the weapon a vehicle can support. Large artillery weapons allow the barrel to spring backwards and use a configuration of pistons and pipes containing liquid (which is usually very slightly compressible) and gas (which is much more compressible than liquid) to absorb the recoil (Denny 70). See figure below:

 

 

 

 

There is another form of artillery that completely lacks a recoil absorption mechanism.

mortars are powerful, yet small because they do not require recoil dampening mechanisms
mortars are powerful, yet small because they do not require recoil dampening mechanisms

They are called mortars and are designed to fire large rounds at high angles; approximately 45° – 85°. Apart from the occasional usefulness of the steep launch angle, mortars are advantageous for their light-weight mobility, simplicity and easy maintenance (Pincevičius, Jonevičius, and Baušys 114). Because mortars are fired with such a steep angle, their recoil force is absorbed by the ground which allows for the weapon to be simplified to little more than a tube, transforming a very high power weapon into something highly mobile. Mortars are sometimes used to launch projectiles over barriers and also attack elevated targets.

 

ROCKETS/MISSILES

 

As we saw, a big concern with artillery weapons is recoil. Rockets and missiles are distinct from artillery because they are accelerated by propelling burnt fuel out the tail end, again using Newton’s third law to accelerate the projectile forward. Since missiles are not launched by expanding gasses in a chamber, there is no recoil because the gasses aren’t pushing back on anything. This is a pure, homogenous application of Newton’s third law. Without recoil, rockets can be launched essentially from any platform including off a soldier’s shoulder.

 

Inter-Continental Ballistic Missiles, (ICBM), are capable of traveling thousands of miles. At

Trident II SLBM launched by ballistic missile submarine
Trident II SLBM launched by ballistic missile submarine

such a long range, missiles need guidance to insure that they hit their target precisely. This is often achieved partially on board with inertial sensors such as gyroscopes and accelerometers (Beckett 39). These sensors react to a change in velocity, so if a missile, in its several thousand mile journey, encounters such a force as strong winds, it will be able to correct its path using computers that process the signals from the inertial sensors. However, over such a long distance, programming a trajectory for the missile to hit its target can be extraordinarily complicated as some factors to consider include the curvature of the earth as well as the Coriolis Effect, or the rotation of the earth under the missile as it travels through different latitudes. A simple ballistic curve, even with inertial guidance, may not produce a sufficiently accurate weapon. Therefore, ICBMs require sophisticated sensors and guidance software in order to correct course and hit their targets with a higher degree of precision (Beckett 39). These sensors include infrared heat-seekers, GPS, and laser guidance systems.

 

Beyond the ability to stay on course over long distances, guided missiles have the added advantage of striking targets with a high level of discrimination. In Death by Moderation, David A. Koplow suggests that some enemy forces store military assets and personnel in immediate proximity of civilians and civilian infrastructure in order to discourage airstrikes, and for a ‘no boots on the ground’ mission, a solution to this problem is precision guided missiles (79-81). This addresses an ethical concern of modern US military: limiting civilian casualty while inflicting maximum damage to enemy forces.

 

BOMBS

 

The most devastating bomb today is the nuclear variety. “The key to nuclear energy lies in the neutron – an electrically neutral particle which, along with the positively charged proton, comprises the nuclei of all atoms heavier than hydrogen” (Beckett 8). A uranium bomb works by igniting a chain reaction of fission. Fission is when the nucleus of an atom

fission of Uranium nuclei
fission of Uranium nuclei

splits, forming two smaller atoms. Uranium bombs use the rare but natural isotope Uranium-235 which has 143 neutrons. It turns out that adding a single neutron to the nucleus makes the isotope highly unstable, causing the atom to split almost instantaneously into two smaller atoms. The resulting atoms, or fission products, are uncertain, but are usually in the middle of the periodic table such as barium, krypton, and bromine (Beckett 9). Additionally, the Uranium isotope expels three more neutrons at high speed which carries on the reaction. The details are relatively unimportant here, but where the bomb gets its energy is important. Einstein’s famous equation says that energy and mass are the same things, only in different forms:

                                                E = mc2                                       (2)

E in Joules, m in Kilograms, and c in meters per second

Here, c squared is the speed of light (which is constant) squared, which is 90 quadrillion (m/s)2. That’s 9 with sixteen zeros. This is relevant to fission because the uranium bomb gets its energy from the fact that the sum of the mass of the fission products weighs slightly less than the original Uranium-235 atom. Thanks to equation (2), we know that the mass doesn’t just disappear; it’s converted into the kinetic and thermal forms of energy. It is weird to think about, but the reason a Uranium bomb can release so much energy in spite of being only 0.1% efficient in converting mass into usable energy, is because the speed of light is so great.

 

Due to the extreme and collateral destructive powers of nuclear weapons, it is inconceivable to many that such a weapon should ever be used in anything short of an ‘end of the world’ situation. However, the average person has not researched nuclear physics and some people will even chide nuclear energy as being dangerous in the same sense that atom bombs are dangerous, as though they were the same thing. These false preconceptions are an injustice to this particular field of study. Granted, there is no denying that the US and other countries possess nuclear weapons capable of obliterating entire cities, but Koplow advances an argument in scenario 5 of Death by Moderation in which low-yield nuclear weapons are the only possible way to prevent the mass death of innocent civilians. As previously described, nuclear weapons operate on a chain reaction principle in which unstable atoms split into two smaller atoms, or fission products, in addition to ejecting free neutrons which become imbedded into surrounding nuclei, destabilizing those atoms to carry on the reaction. A sustained chain reaction is only possible if certain criteria are met, one being critical mass. Critical mass is a minimum mass of fissionable material required in order to produce a sustained chain reaction. We can produce a smaller nuclear weapon by reducing this critical mass in part through the use of metallic neutron reflectors (Beckett 11). A low-yield nuclear weapon can be used to attack enemies within stone mountainside caves impervious to traditional weapons (Koplow 105). Another use for nuclear bombs is destroying chemical and biological weapons stockpiles. Using traditional weapons to do this can prove disastrous as it will unleash these weapons into the air which would be devastating to civilians and exaggerated by weather conditions. Koplow says the intense heat from a well-placed nuclear explosion can disarm these weapons by incinerating them (105-106).

 

ANTI-SATELLITE WEAPONS (ASAT)

 

Many people may not have the impression that space satellites can play a significant role in warfare in modern days. Surprisingly however, satellites have been a focus of the military for decades. In 1984, “The most abundant satellites [were] those that moniter[ed] happenings around the world in a variety of ways. Such surveillance or spy satellites account[ed] for roughly half of the 120 military satellites launched each year… Objects only 15 to 30 cm across [could] be spotted on the best spy satellite images” (Hecht 244). Satellites are prime targets for an enemy because they can collect vital information such as weather, GPS, and the location of enemy gatherings. There are some methods by which a satellite can be attacked (choosing which method though can be tricky for tactical reasons).

 

rendition of an ASAT missile
rendition of an ASAT missile

Perhaps as early as 1963, the Soviet Union was developing killer satellites, essentially a kamikaze satellite loaded with explosives that approaches its target and then detonates. The Soviet Union performed tests of these ‘killer’ satellites on other Soviet satellites. This style of ASAT weapon is limited to satellites of low-earth orbit – between 230 and 1000 kilometer altitudes (Koplow 162). Though it’s not the only country that has, the US has also successfully destroyed satellites in tests using missiles launched from earth (Koplow 164)

 

 

Apart from ‘brute force’ methods, there are plenty of more sophisticated ways to attack satellites. Since satellites are new technology (less than a century old), they have a number of vulnerabilities waiting to be exploited. One such weakness is the thermal nature of outer space. Hot objects in the earth’s atmosphere cool off relatively quickly through a process called induction in which the object transfers its thermal energy through contact with the surrounding air until the object is the same temperature as the air. With no matter to contact, objects in outer space can only cool off through a process called radiation. The thermal energy of the object leaves the object in the form of electromagnetic waves, which is just a fancy term for light. However, the frequency emitted is too small to be seen with our eyes. The cooling process of radiation is much slower than that of induction, making satellites vulnerable to being slowly overheated with high frequency lasers to the point of damaging the electrical components (Hecht 252). It is important that the laser be of a high frequency because it is the high frequency light waves that get absorbed easily by matter and absorption is what causes the energy of the wave to transform into thermal energy. This is why we don’t have to worry about x-rays from the sun, because they quickly get absorbed in the upper atmosphere while lower energy light waves make it to the surface. The energy of an ‘indivisible light wave segment’, or photon, is defined as:

                                                E = h f                                        (3)

E measured in Joules, frequency f measured in oscillations per second of the light wave

‘h’ is the letter for Planck’s constant, which is 6.626 * 10-34 Joule Seconds. While it is important to have a high frequency beam to transfer as much thermal energy as possible to the satellite, the beam cannot have too high of a frequency or else it will be heavily degraded in the earth’s atmosphere before it reaches its target (Hecht 254). This can be accounted for by increasing the intensity, or number of photons per second per unit area. In the case of foul weather obstructing the target satellite, an orbiting mirror can be used to reflect the beam onto the target (Hecht 254). Lasers are also useful for damaging sensors which would disable that function of the satellite.

 

Attacking satellites can be tactically risky. In many cases, non-military satellites can be used for military purposes as exemplified in Koplow’s scenario 7 (150-152). This introduces the problem of creating conflict and possibly new enemies where there were none before. It can be especially challenging if the owner of the satellite is a neutral country independent of the enemy. Rather than outright destroying the satellite, certain signals from the satellite can be jammed only for a specific region of its orbit to limit the information the enemy can gather while minimizing the intrusiveness of the US military on the foreign satellite.

 

BEAM WEAPONS

 

Beam weapons are known as ‘directed energy’ weapons and they are the most recent class of weapons presented in this list. Beam weapons consist of a stream of waves, such as electromagnetic waves which is what all light is made of (visible and invisible). “The pentagon is also looking to beam weapons to save money. That may sound strange, given that a battlefield laser system would probably cost at least $5-$10 million, and that particle-beam systems would probably cost even more. Yet … As short-range missiles have increased in sophistication, their prices have soared. Surface-to-air Stinger missiles

A non-lethal handheld laser weapon available to civilians that is designed to inflict a highly painful but temporary skin burn
A non-lethal handheld laser weapon available to civilians that is designed to inflict a highly painful but temporary skin burn

… have a 3 mile range … [and] cost about $20,000 each” (Hecht 267). Officials estimate that a carbon dioxide laser will use only a few hundred dollars’ worth of fuel per shot, and a couple thousand dollars per shot for a fluoride laser (Hecht 267).

 

 

There are essentially two broad types of beam weapons: laser and particle. Particle beam weapons cause tremendously more damage than laser beam weapons, as they are compared in function to lightning strikes (Hecht 141), but the charged particles in a beam have a much greater tendency of breaking up in the atmosphere (Hecht 144). Also, moving charges are curved through magnetic fields at a rate proportional to their velocity:

                                        F = q v B Sin(θ)                                 (4)

Force in Newtons, charge ‘q’ in Coulombs, velocity in m/s, Magnetic field strength ‘B’ in Teslas

 

The sin(θ) element of the above equation causes the force on the charged particle beam to be strongest when the beam is moving perpendicular to the earth’s magnetic field (sin(90°) = 1, the maximum value of a sin term), which generally runs from the south to north poles. Additionally, what is not mentioned in equation (4), which is a simplified version, is that the force on the particle is perpendicular to both the velocity and magnetic field, so that a particle beam traveling some amount west will always curve down and will always curve up for east bound trajectories. This problem can only be avoided by beaming the particles parallel to the magnetic field which is easier said than done as the earth’s magnetic field is not as uniform as people may think. All in all, particle beams are currently impractical long-range weapons.

 

 

 

Particle beams are produced, in part, the same way particle accelerators for studying subatomic physics work, such as the Large Hadron Collider. Understanding the details requires some background in physics but a basic understanding is not too difficult.

In this diagram, the charged particles are only accelerated in the gap between the D shaped electrodes. That gap contains an electric potential, or voltage difference which

particle accelerator
particle accelerator

pushes on charges, accelerating them. The direction of the alternating electric current is reversed at just the right times to reverse the direction of the force applied to the particle when in between the electrodes to insure it is being accelerated in the right direction every time it comes around. The particle follows the curved dotted lines due to the effects of an applied magnetic field discussed earlier with equation (4). The diameter of the curved path of the particle increases at higher speeds and the particle is ejected when it has no more room to accelerate.

While particle beams may not currently have a place in long range weaponry, they can be used defensively over short ranges. They can be used to shoot down approaching missiles, for instance. An advantage to using particle beams is that the strength of the beam can easily be varied to adapt to the situation.

 

“Laser physics, based on a quantum-mechanical view of atoms and molecules, is called ‘quantum electronics’ by the physicists working in that area. The field is an outgrowth of the revolution in our understanding of physics that took place during the first part of the twentieth century, and an explanation requires laying some groundwork-describing fundamental concepts of atomic physics and quantum mechanics”(Hecht 53-54). Without going into too much detail, electrons that orbit a nucleus have quantized energy states, meaning they can only exist with specific amounts of energy. The farther the electron is orbiting from the nucleus, the more energy it has. Quantum physics says that the electron can only orbit at specific distances (specific energies) from the nucleus and nowhere in between, constraining the electron to jump between orbitals when excited with energy. When an excited electron loses some energy, it jumps back down to the ground state, and since energy must be conserved (never disappear, only change forms), the electron instantaneously emits a photon to account for its drop in energy. As seen in equation (3), to produce a high frequency laser beam, we must excite the electrons in the atom to a high energy state in order to release high energy photons, which characteristically have high frequencies.

infrared imagery is used to find warm objects. Cameras sensitive to infrared frequencies of light are used in heat-seeking applications
Infrared imagery is used to find warm objects. Cameras sensitive to infrared frequencies of light are used in heat-seeking applications

 

 

Considering all of the new innovations in military technology, failing to keep up with new developments in science and technology can prove to be a fatal mistake. Jeff Hecht says that “Argentine commanders on the Falkland Islands reportedly decided to surrender after British forces let them overhear plans to drop laser-guided bombs on their headquarters” (203). In order to remain a powerful military force, America’s arsenal needs to be constantly maintained and updated. If the American military allows itself to fall behind the times of today, it will open a door straight through our defenses.

 

 

 

 

 

 

Works Cited

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Demonstration of Optical Transport, Sorting and Self-arrangement Using a ‘tractor

Beam’.” Nature Photonics 7 (2013): n. pag. Www.nature.com/nphoton. Nature, 20 Jan.

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Cogan, Sarah. “Seeing through Walls: Laser System Reconstructs Objects Hidden From Sight.”

The Optical Society (2012): n. pag. Www.osa.org. 6 Aug. 2012. Web. 28 Oct. 2014.

Cyclotron. Digital image. Hyperphysics.phy. Hyperphysics, n.d. Web. 29 Nov. 2014.

Denny, Mark. Their Arrows Will Darken the Sun: The Evolution and Science of

Ballistics. Baltimore: Johns Hopkins UP, 2011. Print.

Earth’s magnetic field lines. Digital image. Geomag.org. N.p., 2008. Web. 29 Nov. 2014.

<http://geomag.org/info/Declination/magnetic_lines_2010.gif&gt;.

Hecht, Jeff. Beam Weapons: The next Arms Race. New York: Plenum, 1984. Print.

Koplow, David A. Death by Moderation: The U.S. Military’s Quest for Useable

Weapons. Cambridge: Cambridge UP, 2010. Print.

Laurean-Georgel, Oprean. “TRANSFORMATIONS AND ISSUES REGARDING THE

ARTILLERY AND ROCKET SYSTEMS.” Revista Academiei Fortelor Terestre. Nicolae

Balcescu Land Forces Academy, 1 Oct. 2014. Web. 28 Oct. 2014.

Pincevičius, Albertas, Vaclovas Jonevičius, and Romualdas Baušys. “External Ballistics Task

Modelling Features.” Aviation 15.4 (2011): 112-16. Taylor & Francis Online. Web. 11

Dec. 2014.

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