The US Army has revealed that it is working on a supergun with a range of 1,000 miles. The Pentagon says it will have a prototype ready by 2023, although when and if such a weapon actually enters into service isn’t known.

If the project is completed and works, it could be deployed worldwide including places such as Japan and Korea in Asia, in NATO countries, particularly those in the east, even in the Middle East (i.e., Saudi Arabia).

V-3 Retribution Weapon

The idea of a supergun is nothing new. It traces back to the 1880s where prototypes were tested in the United States, France and Germany. Nazi Germany built a very long-range supergun, known as the V-3 “Retribution Weapon”  (Vergeltungswaffe) that went into service initially to bomb London. Based in two bunkers in France’s Pas-de-Calais, the Allies bombed and destroyed them. Two other V-3’s were used to successfully bomb Luxembourg in late 1944 and early 1945, but didn’t do much damage. Hitler authorized the V-3 project after Peenemünde was successfully bombed by the Allies.

Peenemünde was where the V-1 and V-2 rockets were manufactured, but late in the war production of the V-2 was moved to an underground site in Thuringia. Hitler hoped the V-3 would help in his attempt to knock England out of the war.

Project Babylon

The second major attempt at a supergun was Gerald Bull’s “Project Babylon” PC-2 supergun, which the Canadian artillery expert designed for Iraq’s Saddam Hussein. PC-2 was a cover name – short for Petrochemical Complex-2 – intended to hide the real purpose of the project. The actual designation of the largest version of the Bull supergun was S-1000.

The Royal Armouries in Hampshire, England, have part of the ‘Supergun’ ordered by Saddam Hussein and designed by Gerald Bull. Photo: AFP

A CIA report that was previously classified has been released, with some redactions. According to the report, the Bull supergun would have a range of 1,000 kilometers (621 miles) and would fire a type of ammunition known as a discarding sabot. A discarding sabot is a device that centers a munition in the barrel of a gun, but when the gun is fired the sabot is discharged and falls away. A key purpose is to allow the projectile to be aerodynamically designed, typically including fin stabilization so as to increase the accuracy of the round.

There are two different approaches to the design of a supergun. The first, and oldest is to sequentially charge the projectile as it traverses the barrel of the gun tube. The idea is by adding force to a projectile already accelerating in a gun tube, the projectile would gain speed and therefore range. The earliest approach was to set charges along the barrel that would fire off at 45-degree angles to the accelerating shell, increasing its velocity. The US inventor Azel Storrs Lyman was granted a patent for such a gun system in 1857 (‘Improvement in accelerating firearms’).

One of the problems in this approach is how to get the staggered additional charges to fire off with the right timing. If the timing isn’t exact, the shell might actually slow down or even explode inside the barrel. A secondary issue is how to prevent tremendous wear and tear on the barrel caused by the exploding charges.

In the V-3 the intent was to fire repeatedly and quickly at the target – the city of London. The V-3 was not capable of pinpoint attack. It was mostly intended as a terror weapon, just like Allied carpet bombing – including incendiary bombs – dropped on German cities, the most notorious being Dresden. Before the atomic bomb in 1945, the Allies also heavily bombed Japanese cities, including the devastating fire-bombing of Tokyo.

There are three methods for setting off charges inside a gun barrel, sequentially and on time. One is mechanical, where the initial firing and sequential explosions are set off based on a fixed timing system. The second is electrically, which potentially offers a more efficient solution for accurate timing. And a third, perhaps the method the V-3 used, was to bleed off blast gases to trigger the sequential explosions in the gun tube.

The second general approach for a supergun is to use a rocket assist, with one or two stages, to extend the range of a supergun. The advantage of this approach is that it is more cost effective than a multi-stage rocket without a gun. The gun provides very rapid acceleration, much more quickly than a rocket launch. One of Bull’s planned versions of the S-1000 would use a rocket as a second (or even a third) stage, allowing the gun to set the initial speed of the shot.

The Bull gun, like the V-3, was not supposed to be particularly accurate, and because of its great size and barrel length, had to be mounted in a fixed site. That made physical aiming beyond what was built into the initial barrel positioning, impossible. The Bull gun for Saddam, based on where its remains were found, was aimed at Tel Aviv.

US Army approach

We actually know very little about the new US Army project, but enough has been released to suggest that the army supergun will differ from the V-3 and S-1000 because its goal is high accuracy. Billed as a Strategic Long Range Cannon (SLRC), the purpose of the army’s SLRC supergun is to have a long-range standoff weapon that can take out enemy defenses, such as air defense missile sites, including the Russian S-400.

Thus, the army gun will have to be a precision fire weapon, and to achieve precision fire it will need to be steerable and have some kind of localizing capability to go after targets that may be semi-mobile.  For example, the S-400 can move and be set up in only a few minutes, making targeting difficult without some moving target indicators and sensors, and the ability to adjust flight paths (meaning it will require long-range data links of some kind).

The Italians have demonstrated, with a much smaller (76mm) gun that steering a fast moving gun launched projectile is practical. The Oto Melara-designed projectile, called DART, uses a discarding sabot, fin stabilization and data links to achieve very high accuracy and rapid fire – up to 120 rounds per minute.

The US Army gun will also need to be able to accelerate the projectile in order not to be intercepted by enemy standoff weapons. For example, the Russian 40N6E long-range interceptor missile (part of the S-400 extended-range missile defense suite) is probably capable of intercepting a long-range gun fired missile or shell even if it was traveling at the lower-end of the hypersonic speed envelope. There is no information that any Army supergun will reach hypersonic velocities through its flight course.

An open question is whether the need for a heavy gun with a relatively long barrel is interesting enough to replace already existing forms of standoff weapons. The US Army does not currently have long-range standoff weapons – like the Air Force, Navy and Marines – and it may be that the pursuit of the old supergun idea is a way for the army to get in the stand-off business.

An electro-magnetic railgun that was developed by the Pentagon and the US Navy. Photo: YouTube screengrab.

A poor record

The history of the supergun tells us that none of them has really been successful, either because there were design shortcomings and failures, or because they were so expensive and inflexible to be not worth the effort to build and deploy them.

The German guns aimed at London were destroyed by allied bombing and Saddam’s project was never completed, and even if it had been put into operation, the supergun was not a big concern for the allies, who already knew about it through intelligence sources, but never bombed the experimental sites.

Israel, for example, was much more worried about Gerald Bull’s work on Saddam’s Scud missiles. Bull was re-engineering the Scuds to make them more accurate and reliable but never finished the job. In 1991, Iraq launched 39 Scud missiles against Israel aimed at Tel Aviv, Haifa and probably the Dimona nuclear facility in the Negev. After being warned (probably by Israel) a number of times to halt his work for Saddam, Gerald Bull was assassinated on March 22, 1990, in Uccle, Belgium.

Thus, today the US Army is trying once more to build a supergun. As the American baseball player and sage Yogi Berra said, “It’s déjà vu all over again.”