Airsoft Blog

Airsoft, like any other sport, involves many scientific principles that go relatively unnoticed.  In the heat of battle, one rarely worries about something like the transfer of kinetic energy.  While knowing airsoft physics will not realistically help you in a game, the principles are good to know.  Knowledge of pellet ballistics, on the other hand, can help you with your game.

Pellets transfer very small amounts of kinetic energy mainly because of their size.  The transfer of energy is basically the power of impact.  Airsoft and paintball energy transfers have been compared, and paintball transfers substantially more energy.  Energy transfers are measured in joules, the SI derived unit of energy.  A standard .20g BB traveling at 300ft/s transfers .8 joules, while a standard paintball traveling at the same speed transfers almost 12 joules.  Energy transfer can actually be calculated using a mathematical formula; E = 1/2mv², where E is joules, m is mass in kilograms, and v is velocity in meters per second.  Since paintballs transfer more kinetic energy, they could be considered more damaging than airsoft pellets.

The weight of airsoft pellets significantly affects their speed and trajectory.  The lighter a pellet is, the faster it will travel, but it will also be less accurate due to the fact it will be more susceptible to environmental factors like wind.  Heavier pellets have straighter trajectories, so they are favorable to lighter pellets, but in many cases heavier pellets cannot be used because the airsoft gun utilizing them is not strong enough to propel the pellets at a fast rate.  Therefore, players that wish to use pellets heavier than .25g usually need to upgrade their gun.  Another benefit of heavy pellets is that they decelerate slowly, unlike light pellets, which start fast but quickly lose speed.  Airsoft snipers usually use .30g pellets because of their high stability, but sniper weights can reach as high as .43g (although very expensive upgrades are required to use this grade of pellet).  The heaviest pellet is .88g, which is never used in airsoft because it is incredibly slow, not to mention very dangerous, as it is usually made of steel.

Pellet velocity is determined primarily by the tension of the spring being used to propel the pellet, or in the case of gas airsoft guns, the type of gas being used.  Energy transfer is relative to the speed of the pellet, and speed is also heavily affected by weight.  For example, a .12g pellet using .800J (the common energy rate of airsoft) of energy will initially travel 375fps.  However, a .20g pellet utilizing the same amount of energy only travels about 280fps, and a .45g pellet will travel at about 200fps.  For a .45g pellet to reach the velocity of a 375fps .12g pellet, it would need to utilize more than 2.50J of energy.

Bernoulli’s principle is the method through which pellets fly.  It is, interestingly, also the principle through which airplanes attain lift.  Bernoulli’s principle states that the velocities of fluids increase with a decrease in pressure.  In relation to airsoft, there is a fluid (air) above the pellet at a relatively high velocity, which means the pressure above the airsoft pellet is lower than the pressure under it, as there is a smaller amount of air flowing under the pellet as there is above it.  Therefore, the pressure under the airsoft pellet pushes up and lifts the pellet, allowing it to fly for a long period of time.  Hop-up systems in airsoft guns apply backspin to pellets, making air travel faster along the top of the pellet and creating a larger difference in pressure between the top and bottom. 

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Electric airsoft guns are the most popular type of airsoft gun.  They are usually powered by rechargeable batteries, as using non-rechargeable batteries would be exhausted incredibly quickly.  The batteries power an internal piston, pulling it back and pushing it forward in order to project pellets.  In the case of full automatic guns, this cycling of the piston occurs at a very high rate.  A popular acronym for these “automatic electric guns" is AEGs.  Most AEGs are modeled after real military weapons, such as M16, Steyr Aug, HK MP5, AK-47, M14, HK G36, and many others. 

AEGs can achieve high speeds (of BBs, measured in feet per second) and rates of fire (ROF).  High-quality AEGs can have speeds more than five hundred feet per second, and fire more than two thousand pellets per second.  In cases like this, drum magazines would be used so clips would not have to be replaced frequently.  For a common AEG, a ROF of six hundred rounds per minute and a speed of three hundred feet per second would suffice in an airsoft game.  Remember, the faster an airsoft gun is, the quicker it drains the battery (although very fast airsoft guns have larger batteries).

Speaking of batteries, a wide variety of batteries can be used in AEGs.  As stated, most airsoft batteries are rechargeable.  Batteries are measured in volts (V) and milliampere-hours (mAh), which is a unit of electric charge.  A high mAh indicates the battery will last a long time, and a high voltage indicates the battery can support a high ROF.  The most common battery used in AEGs is an 8.4V large battery with a 2400 mAh.  While 8.4V is the most common battery voltage, some batteries have voltages as high as 12V.  For some airsoft guns, regular AA batteries can be used.

Tokyo Marui, the most popular AEG company, designed the basic mechanism used in most AEGs.  The mechanism consists of a gearbox which holds three gears, which are powered by an electric motor.  The gears turn and pull back a piston against a spring.  Once fully compressed, the spring pushes the piston forward, thus forcing the pellet in the chamber out of the barrel.  Many airsoft guns utilize metal gearboxes, a feature which prolongs the life of the gun and makes it sturdier. 

Many companies, notably Classic Army, have made their AEGs full metal.  Not only does this make the gun nearly unbreakable, but it drastically increases the realism of the product.  An alternative to full metal is reinforced plastic, which has a similar effect.  Other improvements and modifications of an AEG further add to the realism of the device.  More importantly, beneficial alterations can increase the functionality and usefulness of a gun.  However, noticeably useful modifications are usually expensive.

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