The barrel of the Rodman reproduction is about 20 feet long and about 6 feet in diameter at its widest point. When mounted on its iron carriage, the artillery piece will stand about 20 feet tall. The model will serve as the centerpiece of the 9,000-square-foot "Pennsylvania's Civil War" exhibit that opens June 22 at the Heinz History Center. The original 20-inch Rodman cannon was cast in 1864 at the Fort Pitt Foundry, That manufacturing plant was located on the banks of the Allegheny River, just across Smallman Street from the history center. The "20-inch" refers to the interior diameter of the weapon's bore.
The giant gun was built according to a design developed by U.S. Army ordnance officer Thomas Jackson Rodman, the one-time commander of the Allegheny Arsenal in Lawrenceville. Rodman's cannons were made of cast iron and cooled from the inside out by water flowing through the center of the mold. The metal shrank inward as it cooled, producing a stronger barrel far less likely to blow up while being fired. Rodman developed several other military innovations, according to Andrew Masich, president of the Heinz History Center. "He perfected a bullet-making machine that used compression rather than casting," Mr. Masich said. "It allowed workers to crank out thousands of bullets per hour, each uniform in weight and size."
Rodman also designed new cartridges for use in breech-loading, rather than muzzle-loading, weapons. Because they offered increased strength and safety, Rodman cannons could be made much larger. Charged with 200 pounds of gunpowder, the 20-inch Rodman could fire a half-ton ball 4 1/2 miles. The barrel of the smooth-bore, cast-iron artillery piece weighed more than 58 tons and required a special railroad car to transport it to Fort Hamilton in Brooklyn. Its original role was to protect the Verrazano Narrows entrance to New York's upper bay. While it no longer keeps watch over the harbor, the cannon remains near its original location in a small park. The only other cannon Rodman made this size is at Fort Hancock in Sandy Hook, N.J. The model of the Rodman cannon is one of the largest single pieces that the Ohio-based LF Creative Group ever has produced, Mr. Gillum said. With a foot in several different worlds, LF Creative does work for both museums and theme parks, he said.
. . . Full Text Continued at Pittsburgh Post-Gazette, June 10, 2013