Smokeless powder
Smokeless powder is a type of propellant used in firearms and artillery that produces less smoke and less fouling when fired compared to black powder. Because of their similar use, both the original black powder formulation and the smokeless propellant which replaced it are commonly described as gunpowder. The combustion products of smokeless powder are mainly gaseous, compared to around 55% solid products for black powder. In addition, smokeless powder does not leave the thick, heavy fouling of hygroscopic material associated with black powder that causes rusting of the barrel.
Despite its name, smokeless powder is not completely free of smoke; while there may be little noticeable smoke from small-arms ammunition, smoke from artillery fire can be substantial.
Invented in 1884 by Paul Vieille, the most common formulations are based on nitrocellulose, but the term was also used to describe various picrate mixtures with nitrate, chlorate, or dichromate oxidizers during the late 19th century, before the advantages of nitrocellulose became evident.
Smokeless powders are typically classified as division 1.3 explosives under the UN Recommendations on the Transport of Dangerous Goods – Model Regulations, regional regulations and national regulations. However, they are used as solid propellants; in normal use, they undergo deflagration rather than detonation.
Smokeless powder made autoloading firearms with many moving parts feasible. Smokeless powder allowed the development of modern semi- and fully automatic firearms and lighter breeches and barrels for artillery.
History
Before the widespread introduction of smokeless powder, the use of gunpowder or black powder caused many problems on the battlefield. Military commanders since the Napoleonic Wars reported difficulty with giving orders on a battlefield obscured by the smoke of firing. Visual signals could not be seen through the thick smoke from the gunpowder used by the guns. Unless there was a strong wind, after a few shots, soldiers using gunpowder ammunition would have their view obscured by a huge cloud of smoke, and this problem became worse with increasing rate of fire. In 1884 during the Battle of Tamai Sudanese troops were able to break the square of British infantry armed with Martini–Henries because of that. Sharpshooters firing from concealed positions risked revealing their locations with a cloud of smoke.Black powder burns in a relatively inefficient process that produces lower pressures, making it about one-third as powerful as the same amount of smokeless powder.
A significant portion of the combustion products from gunpowder are solids that are hygroscopic, i.e. they attract moisture from the air and make cleaning mandatory after every use, in order to prevent water accumulation in the barrel that can lead to corrosion and premature failure. These solids are also behind gunpowder's tendency to produce severe fouling that causes breech-loading actions to jam and can make reloading difficult.
Nitroglycerine and guncotton
was synthesized by the Italian chemist Ascanio Sobrero in 1847. It was subsequently developed and manufactured by Alfred Nobel as an industrial explosive under the trademark "Dynamite", but even then it was unsuitable as a propellant: despite its energetic and smokeless qualities, it detonates at supersonic speed, as opposed to deflagrating smoothly at subsonic speeds, making it more liable to shatter a gun barrel rather than propel a projectile out of it. Nitroglycerine is also highly shock-sensitive, making it unfit to be carried in battlefield conditions.A major step forward was the invention of guncotton, a nitrocellulose-based material, by German chemist Christian Friedrich Schönbein in 1846. He promoted its use as a blasting explosive and sold manufacturing rights to the Austrian Empire. Guncotton was more powerful than gunpowder, but also was somewhat more unstable. John Taylor obtained an English patent for guncotton; and John Hall & Sons began manufacture in Faversham.
English interest languished after an explosion destroyed the Faversham factory in 1847. Austrian Baron Wilhelm Lenk von Wolfsberg built two guncotton plants producing artillery propellent, but it too was dangerous under field conditions, and guns that could fire thousands of rounds using black powder would reach the end of their service life after only a few hundred shots with the more powerful guncotton. Small arms could not withstand the pressures generated by guncotton.
After one of the Austrian factories blew up in 1862, Thomas Prentice & Company began manufacturing guncotton in Stowmarket in 1863; and British War Office chemist Sir Frederick Abel began thorough research at Waltham Abbey Royal Gunpowder Mills leading to a manufacturing process that eliminated the impurities in nitrocellulose making it a more stable product that was both safer to produce and safer to handle. Abel patented this process in 1865 when the second Austrian guncotton factory exploded. After the Stowmarket factory exploded in 1871, Waltham Abbey began production of guncotton for torpedo and mine warheads.
Improvements
In 1863, Prussian artillery captain Johann F. E. Schultze patented a small-arms propellant of nitrated hardwood impregnated with saltpeter or barium nitrate. Prentice received an 1866 patent for a sporting powder of nitrated paper manufactured at Stowmarket, but ballistic uniformity suffered as the paper absorbed atmospheric moisture. In 1871, Frederick Volkmann received an Austrian patent for a colloided version of Schultze powder called Collodin, which he manufactured near Vienna for use in sporting firearms. Austrian patents were not published at the time, and the Austrian Empire considered the operation a violation of the government monopoly on explosives manufacture and closed the Volkmann factory in 1875.In 1882, the Explosives Company at Stowmarket patented an improved formulation of nitrated cotton gelatinised by ether-alcohol with potassium and/or barium nitrates. These propellants were not suitable for rifles, because rifling results in resistance to a smooth expansion of the gas, but worked well in shotguns which have no rifling.
In 1884, Paul Vieille invented a smokeless powder called Poudre B made from 68.2% insoluble nitrocellulose, 29.8% soluble nitrocellulose gelatinized with ether and 2% paraffin. This was adopted for the Lebel rifle chambered in 8×50mmR Lebel. It was passed through rollers to form paper-thin sheets, which were cut into flakes of the desired size. The resulting propellant, known as pyrocellulose, contains somewhat less nitrogen than guncotton does, and is less volatile. A particularly good feature of the propellant is that it will not detonate unless it is compressed, making it very safe to handle under normal conditions. Vieille's powder revolutionized the effectiveness of small guns because it gave off almost no smoke and was three times more powerful than black powder.
Higher muzzle velocity meant a flatter trajectory and less wind drift and bullet drop, making shots practicable. Since less powder was needed to propel a bullet, the cartridge could be made smaller and lighter. This allowed troops to carry more ammunition for the same weight. Also, it would burn even when wet. Black powder ammunition had to be kept dry and was almost always stored and transported in watertight cartridges. Other European countries swiftly followed and started using their own versions of Poudre B, the first being Germany and Austria, which introduced new weapons in 1888. Subsequently, Poudre B was modified several times with various compounds being added and removed. Krupp began adding diphenylamine as a stabilizer in 1888.
Meanwhile, in 1887, Alfred Nobel obtained an English patent for a smokeless gunpowder he called ballistite. In this propellant the fibrous structure of cotton was destroyed by a nitroglycerine solution instead of a solvent. In England in 1889, a similar powder was patented by Hiram Maxim, and in the United States in 1890 by Hudson Maxim. Ballistite was patented in the United States in 1891. The Germans adopted ballistite for naval use in 1898, calling it WPC/98. The Italians adopted it as filite, in cord instead of flake form—but, realising its drawbacks, changed to a formulation with nitroglycerine that they called solenite. In 1891 the Russians tasked the chemist Mendeleev with finding a suitable propellant. He created nitrocellulose gelatinised by ether-alcohol, which produced more nitrogen and more uniform colloidal structure than the French use of nitro-cottons in Poudre B. He called it pyrocollodion.
file:Cordite Filled Cartridge.JPG|thumb|Close-up of Cordite filaments in a.303 British rifle cartridge
Britain conducted trials on all the various types of propellant brought to its attention, but was dissatisfied with them all and sought something superior to all existing types. In 1889, Sir Frederick Abel, James Dewar and Dr W Kellner patented a new formulation that was manufactured at the Royal Gunpowder Factory at Waltham Abbey. It entered British service in 1891 as Cordite Mark 1. Its main composition was 58% nitroglycerine, 37% guncotton and 3% petroleum jelly.
A modified version, Cordite MD, entered service in 1901, with the guncotton percentage increased to 65% and nitroglycerine reduced to 30%. This change reduced the combustion temperature and hence erosion and barrel wear. Cordite's advantages over gunpowder were reduced maximum pressure in the chamber but longer high pressure. Cordite could be made in any desired shape or size. The creation of cordite led to a lengthy court battle between Nobel, Maxim, and another inventor over alleged British patent infringement.
The Anglo-American Explosives Company began manufacturing its shotgun powder in Oakland, New Jersey, in 1890. DuPont began producing guncotton at Carneys Point Township, New Jersey, in 1891. Charles E. Munroe of the Naval Torpedo Station in Newport, Rhode Island, patented a formulation of guncotton colloided with nitrobenzene, called Indurite, in 1891. Several United States firms began producing smokeless powder when Winchester Repeating Arms Company started loading sporting cartridges with Explosives Company powder in 1893. California Powder Works began producing a mixture of nitroglycerine and nitrocellulose with ammonium picrate as Peyton Powder, Leonard Smokeless Powder Company began producing nitroglycerine–nitrocellulose Ruby powders, Laflin & Rand negotiated a license to produce Ballistite, and DuPont started producing smokeless shotgun powder.
The United States Army evaluated 25 varieties of smokeless powder and selected Ruby and Peyton Powders as the most suitable for use in the Krag–Jørgensen service rifle. Ruby was preferred, because tin-plating was required to protect brass cartridge cases from picric acid in the Peyton Powder. Rather than paying the required royalties for Ballistite, Laflin & Rand financed Leonard's reorganization as the American Smokeless Powder Company. United States Army Lieutenant Whistler assisted American Smokeless Powder Company factory superintendent Aspinwall in formulating an improved powder named W.A. for their efforts. W.A. smokeless powder was the standard for United States military service rifles from 1897 until 1908.
In 1897, United States Navy Lieutenant John Bernadou patented a nitrocellulose powder colloided with ether-alcohol. The Navy licensed or sold patents for this formulation to DuPont and the California Powder Works while retaining manufacturing rights for the Naval Powder Factory, Indian Head, Maryland constructed in 1900. The United States Army adopted the Navy single-base formulation in 1908 and began manufacture at Picatinny Arsenal. By that time Laflin & Rand had taken over the American Powder Company to protect their investment, and Laflin & Rand had been purchased by DuPont in 1902.
Upon securing a 99-year lease of the Explosives Company in 1903, DuPont enjoyed use of all significant smokeless powder patents in the United States, and was able to optimize production of smokeless powder. When government anti-trust action forced divestiture in 1912, DuPont retained the nitrocellulose smokeless powder formulations used by the United States military and released the double-base formulations used in sporting ammunition to the reorganized Hercules Powder Company. These newer and more powerful propellants were more stable and thus safer to handle than Poudre B.