Torpedoes

Torpedoes of the PigBoat era

Torpedoes have always been the submarine's primary weapon. These were incredibly complex machines that took full advantage of the submarine's inherent stealth, and quite often the first indication of a submarine attack is when the torpedo detonates against your ship. The term "torpedo" itself at one time was an all-inclusive term for any underwater explosive device. It wasn't until the Industrial Revolution of the late 19th Century that the technology existed to build a "auto-mobile" torpedo, or one that swam through the water under its own power. After that point fixed or moored underwater explosive devices came to be known as "mines".

The mobile torpedo was actually an Austrian invention. The first torpedo was powered by a spring-driven clockwork device and steered by attached cables. In 1864 Robert Whitehead, an English industrialist and engineer employed by the Austrian government took the original design and greatly improved on it. His new weapon was powered by a two-cylinder reciprocating compressed-air engine, with the air compressed in an internal flask to 350 psi. Testing was quite successful and the Imperial Austro-Hungarian Navy was the first to put the Whitehead weapons into service. He was permitted to sell the designs to other governments and quite quickly many navies had adopted the torpedo.

The U.S. Navy's Bureau of Ordnance (BuOrd) was quick to recognize the potential of the new weapon and by 1869 had established the Naval Torpedo Station on Goat Island in Narragansett Bay off Newport, Rhode Island. The technicians and engineers there immediately set about developing a "fish" torpedo, similar in many respects to the Whitehead model. It was not overly successful in testing despite having operational characteristics similar to the Whitehead device. During this time the USN experimented with torpedo designs from several U.S. inventors, but none of them were successful enough to put into service.

The USN's first operational torpedo was the Howell Torpedo, put into service in 1889. It was driven by a 132 lb flywheel, spun up to 10,000 rpm prior to launching. It had two laterally mounted variable pitch propellers with a range of 200 yards at 24 knots. It had a warhead consisting of 100 lbs of wet-guncotton, a very stable but relatively low powered explosive. It was used on torpedo boats and battleships until about 1898.

The U.S. finally obtained manufacturing rights to the Whitehead designs in 1892 and the E.W. Bliss Company of Brooklyn, NY began turning out examples. The Whitehead weapons were much more capable than the Howell torpedo and they quickly supplanted them in the fleet. Research at NTS Newport and by engineers at Bliss quickly improved on the designs, and several versions joined the fleet. When John Holland's submarine the Holland VI was being tested in 1898 and 1899 it carried two Whitehead Mk 2 torpedoes. Whitehead variations equipped submarines in the A through D-class, but rapid improvements in by the Navy and by Bliss quickly eclipsed those original designs.

In 1904 Frank M. Leavitt, one of Bliss's leading engineers and a brilliant technician, developed a whole new design. Rather than simple compressed air, Leavitt heated the air in an alcohol flame and used that to turn a high speed turbine. This greatly improved performance and operational effectiveness. Successive development lead to the Mk 4 version, the first to be specifically designed to be fired from a submarine. Bliss and Leavitt continued to innovate, and developed the wet-heater steam turbine for the Mk 7 torpedo in 1910. This shot a stream of water into the heated air, with the resulting steam being much more powerful than just the heated air. Bliss continued to be a leading force in torpedo manufacturing in the United States, until the post-war draw down of the Navy Department caused no further contracts to be awarded to Bliss after 1920. All torpedo research, development, and manufacturing would be centered at NTS Newport, with the production acumen at Bliss being lost. This was a decision that the Navy would later come to bitterly regret during WWII.

One of the unusual aspects of torpedoes is that unlike most other weapons they are actually used numerous times, for practice. Torpedoes were the high-tech drones of the day; extremely intricate and built to fine tolerances, thus very expensive. The forward warhead section could be easily removed and replaced with a practice head filled with water (later a calcium chloride solution) that simulated the weight of the warhead but was completely inert. For a practice shot the weapon was set to run under the target and not hit it. At the end of its run the remaining air in the central air flask would be used to blow the water out of the practice head, making the weapon float. It would then be retrieved by the submarine that fired it. The torpedo would then be refurbished with any needed maintenance, and have its air flask recharged and the alcohol fuel tank refilled. At the start of World War II in 1941, most of the torpedoes fired by the USN in those early days as warshots had already been shot dozens of times in exercises.

The table below outlines all of the torpedoes used by USN submarines during the Pigboat era. The Navy put into service many more types than listed here, but they were designed for surface ship or aircraft launching and we will not cover them. The column on the far right contains a link to a page with a section for each weapon. It will have photos and additional information. The data presented here and on the linked pages come from several sources, the three most prominent being in the links below:

• Navweaps.com Torpedoes of the United States
• A Brief History of U.S. Navy Torpedo Development Part 1
• A Brief History of U.S. Navy Torpedo Development Part 2

USN Submarine Torpedoes 1898-1941
Type	Length (Ft-In)	Diameter (In)	Weight (lbs.)	Propulsion/Fuel	Warhead	Exploder	Speed (Kts)	Range (yards)	Subs used on/Dates of service	Link to photos & more info
Whitehead Mk 2 & Mk 3	11-8	17.7	845	3 cyl. radial/compressed air	118 lbs wet gun-cotton	War Nose Mk 1 contact	26.5	800	Holland, A, B, C, D-class 1898-1922	Whitehead Mk 2 & 3
Bliss-Leavitt Mk 4 Mod 1	16-5	17.7	1500	Vertical turbine/ alcohol	199 lbs wet gun-cotton	War Nose Mk 1 contact	29	3000	C & D-class 1908-1922	BL Mk 4 Mod 1
Bliss-Leavitt Mk 6	17-0	17.7	1800	Horizontal turbine/ alcohol	200 lbs wet gun-cotton	War Nose Mk 5 contact	35	2000	E, F, G, H-class 1911-1922	BL Mk 6
Bliss-Leavitt Mk 7	17-0	17.7	1588	Wet-heater steam turbine/ alcohol	205 lbs TNT	Mk 3 Mod 1 contact	35	4000	K, L, M, N & O-class 1912-1945	BL Mk 7
Bliss-Leavitt Mk 9 Mod 1B	16-4	21	2377	Wet-heater steam turbine/ alcohol	395 lbs TNT or Torpex	MK 3 Mod 2 contact	34.5	5500	R & S-class 1915-1945	BL Mk 9 Mod 1B
Bliss-Leavitt/BuOrd Mk 10 Mod 3	16-4	21	2215	Wet-heater steam turbine/ alcohol	497 lbs TNT or 485 lbs Torpex	Mk 3 contact	36	3500	R & S-classes, some fleet boats 1915-1945	BL Mk 10 Mod 3
BuOrd Mk 14	20-6	21	3000	Wet-heater steam turbine/ alcohol	507 lbs TNT or 668 lbs Torpex	Mk 6 influence/contact	46 or 31	4500 or 9000	Fleet boats 1931-1978	BuOrd Mk 14
Westinghouse Mk 18 Mod 1	20-6	21	3061	Electric	595 lbs Torpex or HBX	Mk 8 contact	29	4000	Fleet boats 1943-1950	Westinghouse Mk 18 Mod 1
BuOrd Mk 23	20-6	21	3000	Wet-heater steam turbine/ alcohol	507 lbs TNT or 668 lbs Torpex	Mk 6 influence/contact	46	4500	Fleet boats 1943-1946	BuOrd Mk 23