1 – Shaped Charges: An Accidental Discovery

Sometimes, technological discoveries are unexpected, such as the one described in an article in the 1888 issue of Scribner’s magazine¹. The article centered on Charles E. Munroe’s experience at his unique (and dangerous) job. Munroe was a civilian chemist assigned to work at the U.S. Naval Torpedo Station in Newport, Rhode Island (Figure 1). His job? Detonate blocks of guncotton (nitrocellulose) explosives and observe the effects of the blasts on various materials, including iron plate.

The increasing possibility of naval warfare between vessels armed with torpedoes guided his research. He knew that powerful combat ships had recently launched, including the Kotaka, a Japanese torpedo boat that was the largest in the world in 1886. The powerful Italian cruiser Monzanbano, launched in 1888, had multiple torpedo launchers and was conducting tests in the Mediterranean Sea. Many more torpedo-armed vessels were under construction or would soon launch². If a war started, the U.S. Navy needed information from Munroe’s experiments to make their torpedoes capable of penetrating armored warship hulls.

In one of his experiments, Munroe placed a guncotton cylinder on an iron plate. The cylinder, molded at the Naval Station, had USN and 1884 stamped into its flat sides. Munroe detonated the explosive. After the smoke cleared, he inspected the results. What he saw was not what he expected. The iron plate had indentations of letters and numbers that corresponded with those on the explosive (Figure 2).

Intrigued by these results, Munroe continued his experiments. He carved a cavity in a small cylinder of guncotton and then placed it, cavity-end down, on an iron plate. After detonating the explosive, he observed that the explosion formed a deep crater in the steel opposite the detonation point. The cavity focused the blast.

To determine if an assembly containing explosives could penetrate steel, Munroe attached sticks of dynamite around a tin can. He then purchased a small steel safe, placed the assembly on top of it and detonated it. The explosion blew a three-inch hole through the safe (Figure 3). Although this focused detonation was a curious phenomenon, the American military had no interest in turning it into a weapon.

Shaped Charge Research Moves to Europe

Other countries found the technology more interesting. Experimentation in Germany in the 1920s and 1930s resulted in discoveries about lining the charge cavities with thin metal plates³. Franz Rudolph Thomanek, an associate at the Ballistic Institute of Berlin, spearheaded this research effort. A Soviet scientist named Sukharevskii investigated the shaped charge effect in 1925, and an Italian researcher named Lodati produced a technical paper on this effect in 1932. British experiments between 1925 and 1937 yielded data on intensifying the charge effectiveness using various materials and configurations for lining cavities. However, only the German research efforts generated further interest in using the discoveries in weapons.

American Interest Returns

In the late 1930s, the potential of this explosive process for weapons led a resurgence in American study, according to Dr. William Walters, a Research Engineer at the U.S. Army Research Laboratory. In his 2008 technical paper presented at the International Symposium on Ballistics, Walters related that shaped charge experimentation in America began in the Research and Development Service of the U.S. Army Ordnance Department⁴.

Their experiments verified the significant penetration into a plate from a cylinder of explosive with a conical cavity at one end. Testing showed even more penetration if the cavity had a thin metal cone attached to it. Placing the device at a short distance from the target increased penetration even more. Because the shape of the device was a key component, it was called a “shaped charge”.

A Designer From Switzerland

During the 1930s, shaped charge experiments were also conducted in Switzerland. Research performed by Henry Hans Mohaupt, a Swiss inventor, greatly advanced shaped charge technology and its application to weapons (Figure 4). Mohaupt’s design work included lined shaped charges for use in rifle grenades, mortars, and artillery projectiles⁵.

By late 1937, Mohaupt was confident that his inventions would generate interest and income from the British army. He proposed the purchase of his ideas to a British military commission.

After investigating Mohaupt’s devices, the commission recognized the technology was like previous British experiments. In addition, the cost that Mohaupt requested was too high. Consequently, the commission cancelled all further efforts to reach a contract with the Swiss inventor.

A Game-Changer for the U.S. Military

Mohaupt was not discouraged. He contacted the U.S. Army Ordnance Department in late 1940 to arrange a demonstration at the Aberdeen Proving Ground in Maryland.

The Army representatives who attended the demonstration were impressed with the technology. They signed a contract with Mohaupt and initiated a program to use shaped charges in weapons.

Immediately, the Army classified the project as “Top Secret” and excluded Mohaupt from the effort because of his Swiss nationality.

The program produced a shoulder-mounted launcher that fired a rocket with a shaped charge warhead. The weapon offered an infantry soldier the ability to destroy enemy concrete bunkers, armored vehicles, and tanks. Many U.S. soldiers who fought in World War II relied on this ability, starting in the North African country of Algeria.

References

1. Munroe, Charles E., “Modern Explosives,” Schribner’s Magazine, Vol. 3, 1888, pp. 563-576.↑
2. Evans, David C., and Peattie, Mark R., Kaigun: Strategy, Tactics, and Technology in the Imperial Japanese Navy, 1887-1941, Naval Institute Press, 1997, p. 18.↑
3. Kennedy, Donald R., History of the Shaped Charge Effect — The First 100 Years, MRB Schrobenhausen, West Germany, 1983, pp. 7-10.↑
4. Walters, William, A Brief History of Shaped Charges, Twenty-Fourth International Symposium on Ballistics, New Orleans, LA, 2008, Vol. 1, pp. 3-10.↑
5. Mohaupt, Henry Hans, Projectile, U.S. Patent No. 2,419,414, filed October 3, 1941.↑

Join the Discussion!

Shaped charges were initially viewed as an curious phenomenon with no military application. Decades later, the awareness of an impending World War motivated Europeans and Americans into harnessing this technology for weapons.

• Have you ever seen shaped charge technology in action?
• Do you know of other discoveries that were initially ignored but later became crucial oilfield technologies?

I’d love to hear your perspective. Share your thoughts or answer a question in the comments below!