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I Gun (Principles)

发表于 5-26-2022 14:45:21 | 显示全部楼层 |阅读模式
本帖最后由 choi 于 5-26-2022 15:13 编辑

There is no need to read the rest of any document quoted below.

(a) How Do BB Guns Work?  HowStuffWorks, updated Feb 21, 2021

consecutive paragraphs:

"To understand how BB guns work, let's first look at conventional guns. The basic idea behind almost any firearm, from a pistol to a cannon, is to create a small explosion just behind a projectile positioned in a cylinder. When the explosion tries to expand in a gun, it is very limited as to where it can go: The edges of the cylinder are stronger than the force of expansion, so it can't expand out in every direction. The only way it can expand is down the cylinder, the barrel of the gun. If a projectile (a bullet, for example) is in the way, the expanding matter from the explosion will push the projectile forward as it makes its way down the barrel.

"The principle behind BB guns is pretty much the same as in firearms, except there is no explosion. The expanding matter is ordinary air, carbon dioxide or some other gas. Before you fire the gun, the gas is compressed so that it has a greater density, and consequently a greater pressure than the air in the atmosphere outside the gun. The compressed gas is stored in an airtight container until you pull the trigger. This opens up the gas container so the gas can flow out into the barrel, just behind the BB. Since it is more compressed, the gas behind the BB pushes out with greater force than the air in the atmosphere pushes in, and the BB is propelled forward at great speed. This is the idea behind all gas-powered guns, including high-powered air rifles and paintball markers.

"There are several different air-gun designs, which differ mainly in the source of the compressed air:

"• In pneumatic designs, you build up a reservoir of compressed gas by manually pumping air. The movable lever on the bottom of the gun moves a small piston in a tube. Inside the tube, there is a check valve that lets air flow in but not back out. In this way, each pump of the gun increases the amount of air in the reservoir, which has a set volume. Since mass is increased while volume is held constant, the density and pressure of the air increases with every pump.

"• Another common system is the spring air design. In this sort of gun, the 'pump' lever pushes back on a small piston, which compresses a spring behind it. As the piston slides back, it catches on a small, spring-driven latch that swivels on a tiny pin. This latch, commonly called a sear, holds the piston in position, so the spring stays compressed. When you pull the trigger, it pushes on the sear so it lifts off the piston. With the piston unlatched, the spring can expand out, pushing the piston forward. This quickly compresses the air in the chamber behind the BB, building up the pressure needed to propel it down the barrel.

(B) BB gun
("For airguns firing non-spherical pellets, see Pellet gun. For airguns firing 6 mm plastic [spherical] projectiles, see Airsoft gun.  A BB gun is a type of air gun designed to shoot metallic spherical projectiles called BBs (not to be confused with similar-looking bearing balls)"/ section 1 History: explaining the term BB)

section 2 Operation:

"BB guns can use any of the operating mechanisms used for air guns. However, due to the inherent limited accuracy and short effective range of the projectile, only the simpler and less expensive mechanisms are generally used for guns designed to fire only BBs.[citation needed]

"Because the strength of the steel BB does not allow it to be swaged with the low propelling force used to accelerate it through the barrel, BBs are slightly smaller (4.3 to 4.4 mm (0.171 to 0.173 in)) than the internal diameter of the barrel (4.5 mm (0.177 in)). This limits accuracy because little spin is imparted on the BB. It also limits range, because some of the pressurized gas used to accelerate the BB leaks around it and reduces the overall efficiency. Since a BB will easily roll unhindered down the barrel, it is common to find guns that use a magnet in the loading mechanism to hold the BB at the rear of the barrel until it is fired.[citation needed]

"The traditional and still most common powerplant for BB guns is the spring-piston pump, usually patterned after a lever-action rifle or a pump-action shotgun. The lever-action rifle was the first type of BB gun, and still dominates the inexpensive youth BB gun market.

(C) Spring air or spring piston design is Just spring. A few pictures suffice.
• Load Break Barrel Air Rifles Safely. Hard Air Magazine (HAM; 'The best airgun test reviews and news'), July 3, 2014.
https://hardairmagazine.com/buye ... -air-rifles-safely/
("Break barrel air rifles are the most common type of airgun")


• Jim Carmichael, The Often Underrated Compressed Air Gun. Mother Earth News, undated.
https://www.motherearthnews.com/ ... r-gun-zmaz81mjzraw/


In the left lower corner, a gun has its (single) break barrel cocked. (the other two guns presumably cock by different methods). At the top of this illustration, both a pellet and a spring are displayed and marked.

• Dr Amitabha Mukherjee, The Bravo Present --> the Air Gun. In Hands on Lab (July-November 1999): ME371 Project. Department of Mechanical Engineering, IIT Kanpur (IIT = Indian Institute of Technology).
https://www.cse.iitk.ac.in/users ... 1/brijes/index.html


In the illustration, break barrel is red, whose cocking results in compressed spring via a cyan lever.


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 楼主| 发表于 5-26-2022 15:04:18 | 显示全部楼层
(i) lock (firearm)
("The lock of a firearm is the mechanism used to initiate firing. It is an historical term")
(ii) lock (n.1): "Old English loc bolt * * * In firearms, the part of the mechanism which explodes the charge ( [First Known Use] 1540s, probably so called for its resemblance to a door-latching device)"
(i) Flintlock
(section 4 Method of operation: a flint and an anime)
(ii) flint
(quartz; "Flint was widely used historically to make stone tools and start fires. * * * When struck against steel, flint will produce enough sparks to ignite a fire with the correct tinder, or gunpowder used in weapons")
(c) Marshall Brain, How Flintlock Guns Work.
("The flintlock mechanism was the first reliable and relatively inexpensive system for firing a gun, and was hugely popular in colonial America. It was first developed in the mid-1500s * * * The flintlock remained popular until the mid-1800s, when it was replaced by the percussion-cap lock. By the time of the civil war, nearly all guns manufactured used the percussion cap. That means that the flintlock, as a technology, lasted about 300 years!")

(3) percussion cap
Please read the entire Wiki page.
(i) English dictionary
* fulminate (n; First Known Use in this meaning 1824; Did You Know?: "fulmen, Latin [noun neuter] for 'lightning' "): "an often explosive salt (such as mercury fulminate) containing the group −CNO"
(ii) However, the salt fulminate started not as the noun counterpart of the English verb, but as salt of fulminic (accent is on the second syllable mi) acid.

The word fulminic is International Scientific Vocabulary derived from Latin noun neuter fulmen.
(iii) mercury(II) fulminate
(introduction; section 1 Preparation: "Mercury(II) fulminate is prepared by dissolving mercury in nitric acid and adding ethanol to the solution. It was first prepared by [Englishman] Edward Charles Howard in 1800. The crystal structure of this compound was determined only in 2007")

In the right upper corner is a molecule of mercury(II) fulminate, where mercury atom is colored gray, followed at both ends by carbon (black), nitrogen (blue) and oxygen (red).
(iv) mercury (element)
(section 5 Chemistry: "Mercury exists in two positive oxidation states, I [one plus] and II [++]")

(4) cartridge (forearm)
("A cartridge without a projectile is called a blank"/ right upper color for diagram of a cartridge / section 2 History, section 2.2 Modern metallic cartridges: "French gunsmith Benjamin Houllier * * * patented in Paris in 1846, the first fully metallic pinfire cartridge containing powder (and a pinfire), in a metallic cartridge")

section 2 History: "The detonating cap thus invented and adopted brought about the invention of the modern cartridge case, and rendered possible the general adoption of the breech-loading principle for all varieties of rifles, shotguns and pistols. * * * However, this big leap forward [from percussion cap to cartridge] came at a price: it introduced an extra component into each round – the cartridge case – which had to be removed before the gun could be reloaded. While a flintlock, for example, is immediately ready to reload once it has been fired, adopting brass cartridge cases brought in the problems of extraction and ejection. The mechanism of a modern gun must not only load and fire the piece but also provide a method of removing the spent case, which might require just as many added moving parts. Many malfunctions occur during this process, either through a failure to extract a case properly from the chamber or by allowing the extracted case to jam the action. Nineteenth-century inventors were reluctant to accept this added complication and experimented with a variety of caseless or self-consuming cartridges before finally accepting that the advantages of brass cases far outweighed this one drawback.
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