In the early 1990’s the US Navy sponsored a project to build and test a massive 60mm bore, ten-shot, autoloading electrothermal-chemical anti-missile cannon. The huge cannon mechanism and barrel are about 14 feet long and weigh a few tons. The cannon is shown firing test projectiles, but the ultimate goal was to fire guided or steered projectiles which were being developed in another project. Most of the rounds fired in the tests shown are “conventional“ rounds using conventional solid propellant. Some of the rounds, as indicated by the onscreen text, were electrothermal propulsion test rounds. Those used various conventional propellants or mixtures of one or more types of it, plus a high-energy electrical pulse through the propellant, in hopes that the electrical energy would be converted into kinetic energy. The cannon mechanism is of the revolver type, where the revolver cylinder is indexed by hydraulic actuators. There are ten removeable chambers in the cylinder. The rounds of ammunition were typically constructed like plastic shotgun shells, but were bottle-necked, not cylindrical. They had a “high base“ of thick stainless steel, and a body of moulded polyethelyne.
The action of this huge revolver was reminiscent of the M1895 Nagant Russian service revolver, in that there was a mechanism to cause an overlap between the chambers and the barrel at each discharge. This is called a “gas seal“ revolver system. See a more thorough description of the venerable M1895 Nagant “gas seal“ revolver here:
This project was loosely at least part of the Reagan ““Star Wars“ program, aka “Strategic Defense Initiative“ or simply SDI. More info on that late Cold War event here:
The 60mm ETC gun was mounted on a “CIWS“ mounting as used aboard US Navy and navies of other allies. CIWS is the “Close-In Weapons System,“ a radar-controlled 20mm Gatling gun used to defend warships against anti-ship cruise missiles. The USN name for the system is “Phalanx.“ Read more about this sytems here: #hl=en&sclient=psy-ab&q=phalanx close-in weapon system&oq=close-in wea&aq=3m&aqi=g1g-K2g-m1&aql=&gs_l=&pbx=1&bav=on.2,.,&fp=722f4115e977b0af&biw=1053&bih=787
One of the Navy’s press releases on this project reads:
“The 60 mm electrothermal-chemical (ETC) demonstrator was built and tested as part of the Navy’s ship self defense development effort. The program conducted integrated tests of a new 60 mm rapid fire ETC gun/autoloader, CIWS mount, electric pulse power source, and ETC cartridge. The program has resulted in many advances in ETC propulsion including: reliable rapid fire electrothermal (ET) power transfer through a gun breech; repeatable rapid fire gun/propelling charge interface; and demonstration of ETC propulsion in an automatic gun system. Successful operation of the CIWS mount in an ETC environment has shown that EMI is not a significant design issue. The program has successfully proven that ETC technology is moving beyond the laboratory phase and is applicable to advanced weapon system development.“