Rodman gun - AbsoluteAstronomy.com

Rodman gun refers to a series of American Civil War

American Civil War

The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

-era columbiad

Columbiad

The Columbiad was a large caliber, smoothbore, muzzle loading cannon able to fire heavy projectiles at both high and low trajectories. This feature enabled the columbiad to fire solid shot or shell to long ranges, making it an excellent seacoast defense weapon for its day...

s designed by Union

Union Army

The Union Army was the land force that fought for the Union during the American Civil War. It was also known as the Federal Army, the U.S. Army, the Northern Army and the National Army...

artillery

Artillery

Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

man Thomas Jackson Rodman

Thomas Jackson Rodman

Thomas Jackson Rodman was an American artillerist, inventor, ordnance specialist, and career United States Army officer...

(1815–1871). The guns were designed to fire both shot

Round shot

Round shot is a solid projectile without explosive charge, fired from a cannon. As the name implies, round shot is spherical; its diameter is slightly less than the bore of the gun it is fired from.Round shot was made in early times from dressed stone, but by the 17th century, from iron...

and shell

Shell (projectile)

A shell is a payload-carrying projectile, which, as opposed to shot, contains an explosive or other filling, though modern usage sometimes includes large solid projectiles properly termed shot . Solid shot may contain a pyrotechnic compound if a tracer or spotting charge is used...

. These heavy gun

Gun

A gun is a muzzle or breech-loaded projectile-firing weapon. There are various definitions depending on the nation and branch of service. A "gun" may be distinguished from other firearms in being a crew-served weapon such as a howitzer or mortar, as opposed to a small arm like a rifle or pistol,...

s were intended to be mounted in seacoast

Coast

A coastline or seashore is the area where land meets the sea or ocean. A precise line that can be called a coastline cannot be determined due to the dynamic nature of tides. The term "coastal zone" can be used instead, which is a spatial zone where interaction of the sea and land processes occurs...

fortifications. They were built in 8-inch, 10-inch, 13-inch, 15-inch, and 20-inch bore

Smoothbore

A smoothbore weapon is one which has a barrel without rifling. Smoothbores range from handheld firearms to powerful tank guns and large artillery mortars.-History of firearms and rifling:...

. Other than size, the guns were all nearly identical in design, with a curving soda bottle shape, large flat cascabels

Cascabel (artillery)

A cascabel is a subassembly of a muzzle loading cannon - a place to attach arresting ropes to deal with the recoil of firing the cannon.Generally comprising the knob and the neck , with particular models also featuring a filet . By some definitions, the cascabel additionally includes the base of...

with ratchets or sockets for the elevating mechanism. Rodman guns were true guns that did not have a howitzer

Howitzer

A howitzer is a type of artillery piece characterized by a relatively short barrel and the use of comparatively small propellant charges to propel projectiles at relatively high trajectories, with a steep angle of descent...

-like powder

Gunpowder

Gunpowder, also known since in the late 19th century as black powder, was the first chemical explosive and the only one known until the mid 1800s. It is a mixture of sulfur, charcoal, and potassium nitrate - with the sulfur and charcoal acting as fuels, while the saltpeter works as an oxidizer...

chamber, as did many earlier columbiads. Rodman guns differed from all previous artillery

Artillery

because they were hollow cast, a new technology that Rodman developed that resulted in cast iron

Cast iron

Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

guns that were much stronger than their predecessors.

Hollow casting

Guns had been traditionally cast solid and the bore was bored out of the solid metal. With this traditional method, the gun cooled from the outside inward. Castings shrink as they cool. As each succeeding layer cooled it contracted, pulling away from the still molten metal in the center, creating voids and tension cracks. Drilling out the bore removed the voids, but the tensions in the metal were still toward the outside. Rodman devised a method of casting where the gun cooled from the inside out, so that as cooling occurred, it created compression rather than tension. This resulted in a much stronger gun.

With Rodman’s method of casting, a cooling core

Core (manufacturing)

A core is a device used in casting and molding processes to produce internal cavities and reentrant angles. The core is normally a disposable item that is destroyed to get it out of the piece. They are most commonly used in sand casting, but are also used in injection molding.An intriguing example...

was placed in the mold before casting. This core consisted of a watertight cast iron tube, closed at the lower end. A second, smaller tube, open at the bottom was inserted into the first. As the molten iron was poured into the mold, water was pumped through the smaller tube to the bottom of the larger tube. The water rose through the space between the two tubes and flowed out at the top. The water continued flowing as the metal cooled. To further ensure that the gun cooled from the inside out, a fire was built around the iron flask containing the gun mold, keeping the gun mold nearly red-hot. For an 8-inch Rodman columbiad

Columbiad

, the core was removed 25 hours after casting and the flow of water continued through the space left by the core for another 40 hours. Over 50,000 gallons of water was used in the process. For larger guns, the cooling periods were longer and more water was used.

After cooling the gun the machining process began. The bore was bored out proper size, the exterior was turned smooth, the trunnion

Trunnion

A trunnion is a cylindrical protrusion used as a mounting and/or pivoting point. In a cannon, the trunnions are two projections cast just forward of the centre of mass of the cannon and fixed to a two-wheeled movable gun carriage...

s were turned on a trunnion lathe

Lathe

A lathe is a machine tool which rotates the workpiece on its axis to perform various operations such as cutting, sanding, knurling, drilling, or deformation with tools that are applied to the workpiece to create an object which has symmetry about an axis of rotation.Lathes are used in woodturning,...

, and a vent was drilled.

Columbiads were not the only guns cast using Rodman’s method. Dalgren XV-inch shell guns for the U.S. Navy were also hollow cast. A 20-inch hollow cast gun, which may not have been identical to the two guns supplied to the U.S. Army, was sold to Peru

Peru

Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

.

Rodman guns were cast at the Fort Pitt Foundry

Fort Pitt Foundry

The Fort Pitt Foundry was a nineteenth century iron foundry in Pittsburgh, Pennsylvania. It was originally established at Fifth Avenue and Smithfield Street in 1804 by Joseph McClurg, grandfather of Joseph W. McClurg. It was later moved to the area of Pittsburgh now known as the Strip District at...

, Pittsburgh, Pennsylvania

Pittsburgh, Pennsylvania

Pittsburgh is the second-largest city in the US Commonwealth of Pennsylvania and the county seat of Allegheny County. Regionally, it anchors the largest urban area of Appalachia and the Ohio River Valley, and nationally, it is the 22nd-largest urban area in the United States...

;
the Scott Foundry, Reading, Pennsylvania

Reading, Pennsylvania

Reading is a city in southeastern Pennsylvania, USA, and seat of Berks County. Reading is the principal city of the Greater Reading Area and had a population of 88,082 as of the 2010 census, making it the fifth most populated city in the state after Philadelphia, Pittsburgh, Allentown and Erie,...

; Cyrus Alger & Co., Boston, Massachusetts; and the West Point Foundry

West Point Foundry

The West Point Foundry was an early ironworks in Cold Spring, New York that operated from 1817 to 1911. Set up to remedy deficiencies in national armaments production after the War of 1812, it became most famous for its production of Parrott rifles and other munitions during the Civil War, although...

, Cold Spring, New York

Cold Spring, New York

Cold Spring is a village located in the Town of Philipstown in Putnam County, New York. The population was 1,983 at the 2000 census. It borders the smaller village of Nelsonville...

Rodman guns

Rodman guns were all nearly identical in design, with a curving soda bottle shape, the only differences being the size of the gun. They were all smoothbore

Smoothbore

A smoothbore weapon is one which has a barrel without rifling. Smoothbores range from handheld firearms to powerful tank guns and large artillery mortars.-History of firearms and rifling:...

guns designed to fire spherical shot and shell, primarily against ships. The guns were elevated and depressed by means of a lever

Lever

In physics, a lever is a rigid object that is used with an appropriate fulcrum or pivot point to either multiply the mechanical force that can be applied to another object or resistance force , or multiply the distance and speed at which the opposite end of the rigid object travels.This leverage...

called the elevating bar. The point of this lever fits into ratchets on the earliest guns cast, or sockets on the later guns. The fulcrum

Lever

, called the ratchet post, fit on the rear transom of the upper carriage. The ratchet post was cast iron and had several notches for adjusting the position of the elevating bar.

Only one 13-inch Rodman gun appears to have been made, but it was placed in service . Two 20-inch Rodman guns were emplaced at Fort Hamilton

Fort Hamilton

Historic Fort Hamilton is located in the southwestern corner of the New York City borough of Brooklyn surrounded by the communities of Bay Ridge, Dyker Heights, and Bensonhurst, and is one of several posts that are part of the region which is headquartered by the Military District of Washington...

, New York. A third shorter 20 inch gun was cast for the USS Puritan

USS Puritan (1864)

- External links :*...

using the Rodman technology.

The other, smaller Rodman guns were placed in seacoast fortifications around the United States. It took 8 men to load and fire a 10-inch Rodman gun, and 12 men for a 15-inch Rodman gun.

Over 140 Rodman guns survive today and they may be seen at coastal fortifications around the country.

	Length	Weight	Charge	Shot	Shell	Range
M. 1861 8-inch	119.5”	8,465 lb.	10 lb.	65 lb.	50 lb.	3,873 yd. @ 30° (shell)
M. 1861 10-inch	136.7”	15,509 lb.	15 lb.	128 lb.	102 lb.	4,836 yd. @ 30º (shell)
M. 1864 13-inch	177.6”	3,271 lb.	30 lb.	283 lb.	218 lb.	---
M. 1861 15-inch	190”	49,909 lb.	40 lb.	400 lb.	352 lb.	5,018 yd. @ 30º (shell)
M. 1864 20-inch	243.5”	115,200 lb.	200 lb.	1,080 lb.	750 lb.

Rodman guns (continued)

	Number Made	Years Made	Current Survivors	Foundries	Weight Front Pintel Carriage	Weight Center Pintel Carriage
M. 1861 8-inch	213	1861- 1865	56	Fort Pitt Foundry Scott Foundry West Point Foundry	4,899 lb.	4,539 lb.
M. 1861 10-inch	1,301	1862- 1867	99	Fort Pitt Foundry Scott Foundry West Point Foundry Cyrus Alger & Co.	5,031 lb,	4,626 lb.
M. 1864 13-inch	1	1864	0	---	---	---
M. 1861 15-inch	323	1861- 1871	25	Fort Pitt Foundry Scott Foundry Cyrus Alger & Co.	22,800 lb.	21,250 lb.
M. 1864 20-inch	2	1864- 1869	2	Fort Pitt Foundry	36,000 lb.	NA

Carriages for Rodman Guns

Rodman guns were mounted on three type of carriages—a front-pintle barbette carriage, a center-pintle barbette carriage, and a casemate carriage. All of these carriages were made of wrought iron

Wrought iron

thumb|The [[Eiffel tower]] is constructed from [[puddle iron]], a form of wrought ironWrought iron is an iron alloy with a very low carbon...

. All three types of carriage were similar in design having an upper carriage that was paced on a two rail chassis. The gun and upper carriage recoiled along the chassis. The chassis would pivot to train the gun left or right.

The barbette carriages were designed to fire over a parapet and could be used in either permanent or temporary fortifications. The front pintle carriage pivoted at the front of the chassis. This made the gun mount more compact and allowed the gun and detachment to be better protected by embrasures and traverses. The center pintle carriage gave the gun a 360° traverse and was stronger for guns firing at high angles because the pintle, the strongest part of the carriage, would have been under the breech when the gun was fired at high angles.

The casemate carriage was designed to fire from casemates which were chambers in permanent fortifications. The carriage was essentially a front-pintle design, with the pintle fixed in the masonry in front of the chassis and below the guns embrasure. A “tongue’’ connected the chassis to the pintle. The casemate carriage has a lower profile than the barbette carriages.

The 8-inch and 10-inch Rodman guns could be mounted on all three types of carriages. The 15-inch Rodman guns were mounted on both types of barbette carriage. The two 20-inch guns were mounted on front-pintle barbette carriages.

Rodmans in Action

Rodman guns saw little, if any action during the Civil War. Two 10-inch columbiad

Columbiad

s were used in 1864 and 1865 in Union operation against Fort Sumter

Fort Sumter

Fort Sumter is a Third System masonry coastal fortification located in Charleston Harbor, South Carolina. The fort is best known as the site upon which the shots initiating the American Civil War were fired, at the Battle of Fort Sumter.- Construction :...

. It seems likely, due to the time period in which they were used, that these were Rodman guns rather than earlier model columbiads. Other reports of the use of 8-inch and 10-inch columbiads may refer to Rodman guns. The 15-inch Rodman guns were never fired in anger . The 20-inch Rodmans were only fired eight times in practice .

Rifled Rodmans

During the War, and immediately after, attempts were made to cast rifled

Rifling

Rifling is the process of making helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis...

Rodman guns. Unsuccessful attempts were made to cast a 12-inch rifle in 1861, an 8-inch rifle in 1862, and another 12-inch rifle in 1868. . However Robert Parker Parrott

Robert Parker Parrott

Robert Parker Parrott was an American soldier and inventor of military ordnance.-Biography:Born in Lee, New Hampshire, he was the son of John Fabyan Parrott. He graduated with honors from the United States Military Academy, third in the Class of 1824. Parrott was assigned to the Third Regiment of...

at the Cold Springs Foundry near the United States Army Military Academy at West Point used the Rodman water core method of casting to produce large bore rifled guns in 200, 300, and 400 pound models. Parrott rifles that had been cast using the Rodman method were inscribed with the initials WC in order to differentiate those guns from ones that had been cast using ordinary methods. Primarily these guns were used on naval vessels especially large monitors.
In the 1870s and 1880s efforts focused on converting existing Rodman guns into rifles. 10-inch Rodman smoothbore guns were converted into 8-inch rifles. The first method used was inserting a wrought iron rifle sleeve through the muzzle, a similar steel sleeve was also used later. The last method involved drilling and tapping the breech of the 10-inch Rodman and inserting a rifled steel sleeve and screwing it in tight with a threaded breech plug. These breech inserted guns are easily recognized by the square “cascabel

Cascabel (artillery)

” which was designed to provide purchase for screwing the breech plug and liner securely into the gun.

These conversions were not viewed favorably, were primarily seen as cheap stopgaps until modern breech-loading rifles could be developed and emplaced .

Confederate “Rodmans”

In 1859 Joseph R. Anderson

Joseph R. Anderson

Joseph Reid Anderson was an American civil engineer, industrialist, and soldier. During the American Civil War he served as a Confederate general, and his Tredegar Iron Company was a major source of munitions and ordnance for the Confederate States Army.-Early life and career:Joseph Reid Anderson...

of the Tredegar Iron Works

Tredegar Iron Works

The Tredegar Iron Works was a historic iron foundry in Richmond, Virginia, United States of America, opened in 1837. During the American Civil War, the works served as the primary iron and artillery production facility of the Confederate States of America...

, Richmond, Virginia

Richmond, Virginia

Richmond is the capital of the Commonwealth of Virginia, in the United States. It is an independent city and not part of any county. Richmond is the center of the Richmond Metropolitan Statistical Area and the Greater Richmond area...

and Junius L. Archer of the Bellona Foundry, Midlothian, Virginia

Midlothian, Virginia

Midlothian is an unincorporated community in Chesterfield County, Virginia, United States. Founded over 300 years ago as a coal mining village, it is now a suburban community located in the Southside of Richmond well beyond the city limits of Richmond in the Richmond–Petersburg region.It was named...

(the only two gun foundries then operating in what would become the Confederacy

Confederate States of America

The Confederate States of America was a government set up from 1861 to 1865 by 11 Southern slave states of the United States of America that had declared their secession from the U.S...

) failed to adopt the Rodman technique of hollow casting, and as result the U.S. Army cancelled contracts with both firms for casting columbiad

Columbiad

s. Therefore at the outbreak of the war, southern foundries were not capable of casting guns using the Rodman method .

The Confederates did solid cast 8-inch and 10-inch columbiads that resemble Rodman guns. A closer examination of these Confederate columbiads reveals that they have a straighter cylindrical contour between the trunnions and the breech as opposed to the sweeping continuous curve of the Rodman gun. The Confederate columbiads have longer trunnion

Trunnion

s that were intended for use with heavy wooden carriages. The Union gun were designed to be mounted in iron carriages with thinner cheeks, permitting shorter trunnions. The exteriors of the Confederate columbiads are rough, not having been finished on a lathe as were their Union counterparts.

On November 14, 1864, and February 20, 1865, Anderson

Joseph R. Anderson

cast two 12-inch columbiads using the Rodman method at the Tredegar Iron Works

Tredegar Iron Works

. The guns were made too late and were never finished or mounted .

Misnamed as Rodmans

The 3-inch ordnance rifle and the 4.5-inch siege rifle were frequently misidentified as Rodmans. Neither gun was hollow cast. The 3-inch ordnance rifle was made of hammer welded wrought iron and the 4.5-inch siege rifle was conventionally cast.

This error was not limited to those ignorant of artillery; in November 1864 Brig. Gen. J. M. Brannan, chief of artillery in the Union Department of the Cumberland, described the armament of the Chattanooga forts as including several 3-inch and 4.5-inch Rodman guns. (OR, series 1, volume 45, part 1, page 921) First Lieutenant Henry S. Hurter of the 1st Minnesota Light Artillery Battery

1st Minnesota Light Artillery Battery

The 1st Minnesota Light Artillery Battery was an artillery battery that served in the Union Army during the American Civil War. The battery was mustered in at Fort Snelling, Minnesota. on November 21, 1861....

wrote in his report to Oscar Malmros, Adjutant General for the State of Minnesota, "On the 5th of March captain Clayton exchanged the old guns, two 12-pound howitzers, and two 6-pound rifled guns, caliber 3.67, for four new rifled 3-inch Rodman’s guns." The letter was written on November 11, 1864 in Georgia

Georgia (U.S. state)

Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...

External links

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

Hollow casting

Rodman guns

Carriages for Rodman Guns

Rodmans in Action

Rifled Rodmans

Confederate “Rodmans”

Misnamed as Rodmans

See also

External links