US NAVY TORPEDOESby Frederick J Milford
Part One: Torpedoes through the thirties
Reproduced with permission from the April 1996 issue of THE SUBMARINE REVIEW,
a quarterly publication of the Naval Submarine League, P.O. Box 1146, Annandale, VA 2200
Torpedoes have two very important claims to fame, they were the first guided missiles, and they have probably sunk more ships than any other naval weapon. Further, from the viewpoint of sub- surface warfare the torpedo has always been the major offensive weapon of submarines and during WW II it began its development into the pre-eminent anti-submarine weapon. In spite of this, the literature on torpedoes is sparse1. This series of papers is an attempt to chronicle the evolution of U.S.Navy torpedoes, especially self-propelled or automobile torpedoes, from the earliest weapons to those currently deployed. Serious attempts have been made to construct technically correct, but readily understandable explanations of critical aspects of torpedo performance and, at the same time, to avoid some of the shallow explanations that have sometimes appeared elsewhere.AMERICAN UNDERWATER WEAPONS BEFORE 1869
During the Revolutionary War attempts were made by the colonial naval forces to use underwater explosives in attacks by Turtle against HMS Eagle in 1776 and possibly HMS Asia in 1775. Also, floating kegs of gunpowder were launched upstream of Philadelphia in a vain attempt to damage British ships in the harbor. Underwater explosive devices were extensively used by the US Navy during the War of 1812, but had little impact other than to provoke vitriolic letters in the public press. The Civil War 2 produced Farragut's famous "Damn the torpedoes! Captain Drayton, go ahead! Jouett, full speed!" Of course, he was talking about stationary torpedoes or what would now be called mines.________________________
1 The most useful publication covering US Navy torpedoes Jolie's 1978 report "A Brief History of U.S.Navy Torpedo Development", which is very difficult to obtain. It has been largely reproduced in Gerkin "Torpedo Technology" (1989 ) which also contains other material. The NDRC reports "Torpedo Studies" and "Acoustic Torpedoes" are excellent, but report only WW II research and development. A bibliography has been published: "Torpedo Bibliography" Submarine Review April 1995, p.122.
2 Underwater warfare in the Civil War is treated briefly but well in two chapters of Alex Roland's "Underwater Warfare in the Age of Sail" (1978). More detail on the Confederate campaign is given in Milton F. Perry "Infernal Machines: The Story of Confederate Submarine and Mine Warfare" (1965). Accounts from soon after the war are provided in W.R. King "Torpedoes" (1866) and John S. Barnes "Submarine Warfare".
Spar torpedoes were also used with some success and attempts were made to use towed torpedoes. Confederate torpedoes of all types, mostly mines, sank twenty-nine Union ships3 and damaged fourteen others thus sinking more Union ships than all the rest of the Confederate States Navy. The Confederate Navy suffered one ship sunk, the modern ironclad Albemarle, and five damaged by Union torpedoes.
After the Civil War the US Navy entered a period of decline that lasted until the birth of the "New Navy of the United States" in the early eighteen eighties4. During this period of decline, in what must be viewed as a small but significant counter-current and quite possibly a response to the losses incurred during the Civil War, the US Naval Torpedo Station at Newport RI was established.US NAVY AUTOMOBILE TORPEDOES
Early Attempts to Acquire Automobile Torpedoes
When the US Naval Torpedo Station, Newport RI was established on Goat Island in 1869 it was the first establishment in any navy devoted primarily to the development of torpedoes5. The NTS was established at low cost even by the standards of the then impoverished US Navy--the island already belonged to the Federal Government and existing buildings were used. The general mission was the development of torpedoes, torpedo equipment, explosives and electrical equipment6.____________________
3 One of these was the USS Housatonic which was torpedoed in February 1864 by a the Confederate submarine CSS H.L. Hunley operating on the surface using a spar torpedo. This unlucky submarine was destroyed along with the Union ship and had previously killed five crews in attempting submerged operations. The forty three ships are listed by Perry, pp.199-201 and p.4, and his list includes some very small vessels such as ship's launches. Jolie gives somewhat smaller numbers, but does not list the ships.
4 Although there were earlier stirrings of interest in rebuilding the US Navy, especially following the Virginius affair, the beginning "New Navy" is usually taken as the construction of the ABCD ships, Atlanta, Boston, Chicago and Dolphin, which were authorized by Congress in 1883.
5 Recall that it was in 1869 that the Austrian navy acquired rights to the Whitehead torpedo and that the Royal Navy negotiated their first agreement with Robert Whitehead in 1871.
6 The association of electrical equipment with torpedoes was common, but the logic is not easy to follow. There are books on torpedoes and electricity and at least through WW II HMS Vernon, the Royal Navy's torpedo school, was also responsible for electrical training. The connection may have been no more subtle than the early use of electrically detonated mines or the employment of mysterious technology in both torpedoes and electrical equipment.
Improvements in spar torpedoes and stationary torpedoes (mines) were the first projects. The initiation of work on automobile torpedoes (movable torpedoes in the language of the day) at NTS was described by LCdr. Royal Bradford as follows: "In 1869, after the appearance of the Whitehead torpedo, an attempt was made at this Station to construct one similar in principle, so far as known."7 The objectives were loosely stated as:
7 R.B.Bradford "Notes on Movable Torpedoes", Newport: US Torpedo Station, 1882, p.15. The point here is that this was an attempt to replicate the Whitehead torpedo rather than to build a competitive automobile torpedo.
8 Bradford op cit p.15
9 This engine configuration is strikingly similar to that used in the contemporary Mk.46 and Mk.48 torpedoes.
10 Bradford op cit p.17
The difficulties were a hull that was not water-tight, an air-flask that was not air-tight11 and an inadequate engine which, collectively, seem to make Bradford's comment at least an understatement. Attempts to remedy these shortcomings were made in a second torpedo which was tested only at pierside. On the basis of these two torpedoes, plans for a "fish torpedo" were prepared by Lt. Barber and submitted to the Bureau of Ordnance in June 187412. Though the torpedo was not fully successful, it was an auspicious start. The submission of plans to the Bureau is, however, the end of the known record of the NTS Fish Torpedo.
From 1874 until 1891 the development of automobile torpedoes for the US Navy was in the hands of innovative private inventors. The NTS Newport budget was meager13 and its role in these developments was basically to provide test and evaluation facilities. On a world-wide basis, there were well over a dozen of these inventions14. Some were the fruits of the genius of great inventors of the day; others were produced by unknowns. Great ingenuity is evident and some contain the seeds of developments that subsequently became central to torpedo development.____________________
11 The air tank problem certainly reflected the lagging state of the US iron and steel industry a situation that plagued the Navy's initial efforts to build large caliber, steel breech loading rifles for the ABCD ships.
12 The plans may be found in Barber, Francis Morgan, "Lecture on the Whitehead Torpedo", Newport: USN Torpedo Station, November 20, 1874.
13 The total funding for the US Navy "Torpedo Corps" in the July 15, 1870 appropriation was $60,000. The total budget for "General expenses" of NTS Newport for five fiscal years, 1880- 1884, was $295,000, barely covering these costs. For the year ending 30 June 1884 (FY 1884) the budget request for NTS was $50,000 for general expenses, $100,000 for "the purchase of auto- mobile torpedoes" and $55,000 for the purchase of a torpedo boat. Against this request $60,000 was appropriated for general expenses and $100,000 for the purchase of torpedoes. It appears that the latter was so restricted that none of the moneys were spent. It should also be noted that the same act (3 March 1883) appropriated $1,300,000 for the first steel ships of the "New Navy" and so marked the end of the post-Civil War neglect of the Navy.
14 Some of the names and dates for privately invented and developed torpedoes are: Lay (1872), Barber(1873) Ericsson (1873- 77), Ericsson (1880), Lay-Haight (1880-83), Weeks, Wood-Haight (1885), Nordenfelt (1888), Sims-Edison (1889), Cunningham (1893- 94) and, of course, the Howell torpedo (1870-1889). Comments on most of these can be found in Gray or Jolie.
Three of these precursors that are particularly interesting are the electric torpedo, wire guidance and the rocket torpedo. None of these, however, found their way into the US Navy torpedo inventory at the time. Several inventions were submitted in response to a circular letter and subsequently evaluated in detail by the US Navy Torpedo Board in 1883. Of these only the Howell torpedo, which is discussed below, was any sort of success. At this point in time, 1884, the US Navy did not have a usable automobile torpedo, whereas by 1881 about 1500 Whitehead torpedoes had been sold to other navies and by 1884 Whitehead and Schwartzkopf together could probably have produced close to a thousand torpedoes per year.
In addition to the indigenous inventive efforts, the Whitehead torpedo was at least twice offered to the US Navy: In 1869 for $75,000 and in 1873 for $40,000. These offers were declined. Stolen plans and specifications were also offered, and may have been given to the US Navy, by an employee of the Woolwich Arsenal. It appears that in any case the plans were of no real significance in the development of US torpedoes. The full story surrounding the offer and the alleged delivery of the plans would be interesting, but only fragmentary comments have been published.The Howell Torpedo
The Howell torpedo was developed by then LCdr. John A Howell15 beginning in 1870. The development was completed in 1889 and the US Navy ordered fifty Howell torpedoes from Hotchkiss Ordnance Co. of Providence RI in the same year. These seem to be the only production Howell torpedoes that were built. There were, however, other Howell demonstration torpedoes. The torpedo entered service in 1890 and was the US Navy's only torpedo until Whitehead torpedoes produced by Bliss and Williams came into service around 1894. Howell torpedoes continued in service into the twentieth century. In his 1903 report the Chief of the Bureau of Ordnance reported that there were still 36 Howell torpedoes (as compared to 258 Whitehead type) on hand and the Inspector of Ordnance at NTS reported issuing ten to USS Iowa though she was then the only ship still using them16. Although development was slow and its service life short, the Howell torpedo was initially one of the few credible competitors to the Whitehead torpedo and elicited interest in other countries and favorable comment as late as 194517.____________________
15 Development of the Howell torpedo began in 1870 when Howell was a LCdr. By the time development was complete he was a Captain. He retired in 1902 as a RAdm.
16 Secretary of the Navy Annual Report for FY 1904
17 Peter Bethell "The Development of the Torpedo" Engineering October 19, 1945, p.302.
The unique idea of the Howell torpedo was to store energy for propulsion in a heavy cylindrical object rotating at high speed. This idea went through several stages of development. The first proposed version was, even by 1870 standards, very small, about twelve inches in diameter and 48 inches long. It was equipped with propellers at both ends which were on a common shaft together with a cylinder that contained the explosive charge. Thus most of the mass of the torpedo was used to store energy. The whole rotating assembly, except, of course, for the propellers, was contained in an exterior cylindrical shell. The rotating assembly was given a large angular velocity, thus storing energy for propulsion, and then launched18. This proposal was presented to the Bureau of Ordnance in June 1870 and referred to NTS for evaluation. The evaluation was unfavorable, but the Bureau permitted Howell to build a small model. The model ran well enough that Howell, at his own expense, made a full sized torpedo. This also ran, but Howell concluded that having the axis of the flywheel (the rotating charge in these early devices) parallel to the torpedo axis was faulty in principle.
The propulsive arrangement was changed to use a flywheel on a shaft perpendicular to the torpedo axis to store energy with appropriate gearing to drive two propellers at the stern. The development of the Howell torpedo continued with gradually improving performance. The main virtues of this torpedo were good course keeping and the absence of a tell-tale wake. The US Navy service torpedo19, which was designated the Howell Torpedo Mark 1, was 14.2" in diameter, 129.75" long and carried a 96 lb charge 400 yards at 25 knots.Early USN Whitehead and Bliss-Leavitt Torpedoes 1891-1906.
Even as the Howell torpedoes were entering the US Navy inventory, arrangements were being made to procure Whitehead torpedoes. In an interesting arrangement Bliss and Williams (later known as E.W.Bliss and Co.), rather than the US Navy, negotiated a contract with Whitehead that provided drawings, sample torpedoes and a manufacturing license. Bliss, however, had only one customer for its Whitehead torpedoes, the US Navy. The final capitulation and switch to Whitehead torpedoes was probably caused by two factors: Objectively, the range and speed characteristics of Whitehead torpedoes were somewhat superior to those of the Howell torpedo and offered significantly greater growth potential. More subjectively, all other major navies were using Whitehead or Schwartzkopf torpedoes thus causing a definite risk that the US Navy would be left behind if only Howell torpedoes were acquired.____________________
18 The point, of course, was to store the energy required for propulsion as kinetic energy of rotation rather than as internal energy of compressed air.
19 Drake Proc.USN Vol.XIX, 1893, No.1 pp.1-52 contains a very detailed description of the operational torpedo.
E.W.Bliss and Co. produced five varieties of Whitehead torpedoes for the US Navy: 3.55 meter Mks.1, 2 and 3 and 5.0 meter Mks.1 and 2, all 17.7" (45 cm) in diameter. The propulsion systems were compressed air powered, three cylinder, radial Brotherhood pattern engines. All used standard Whitehead pendulum and hydrostat depth control systems20 and the two 5.0 m. and the 3.55 m. Mk.3 had Obry gyros for course control. Another, often overlooked, Whitehead torpedo was used by the US Navy at this time, namely, the Whitehead 5.0 m. Mk.1A21 which was purchased directly from Whitehead. Though it was slightly different in detail, it was operationally interchangeable with the 5.0 m Whitehead Mk.1 produced by Bliss (fewer than fifty 5.0 m. Mk.1A torpedoes were purchased). A total of 43822 of these very standard Whitehead torpedoes were procured. Very similar torpedoes were used in all the major navies at that time.
The torpedo project engineer at E.W.Bliss and Co., Frank McDowell Leavitt saw room for improvement in the Whitehead torpedoes and proceeded to develop what came to be known as the Bliss-Leavitt torpedoes. The distinguishing technical features of these torpedoes as compared to the Whiteheads were, larger diameter (21"), turbine engines, alcohol fired dry heaters and higher pressure air. Operationally the Bliss-Leavitt torpedoes had larger warheads and much longer range, 4000 yards @ 27 k for the Bliss-Leavitt Mk.1 vs 1500 yards @ 28.5 k for the best US Navy Whitehead (5.0 m Mk.2). The first Bliss-Leavitt torpedo, Mk.1, had a two stage, single wheel turbine which produced an unbalanced torque and unwanted gyroscopic effects. Mks.2 and 3 had two counter-rotating turbine wheels which eliminated both problems. In all three the turbine axis was parallel to the torpedo axis.____________________
20 The first Whitehead torpedoes used a simple bellows to measure the hydrostatic pressure and infer the operating depth of the torpedo. This depth information controlled the horizontal rudders to correct any depth error. Unfortunately, this arrangement is unstable. In a stroke of genius, Whitehead added a pendulum to sense the pitch angle and combined the pitch and depth information to control the horizontal rudder. The result was a stable, but not optimized system, which is usually referred to as "Pendulum and hydrostat" control.
21 Probably the Whitehead Fiume 18" Mk.1 or Mk.2 with one or two acquired as part of the licensing package and others purchased separately.
22 This includes Whitehead torpedoes produced by E.W. Bliss and Whitehead, but not the Mk.5. BuOrd Report for FY 1904, p.572.
The use of chemical energy, the heat of combustion of alcohol, was a great innovation, but similar innovations were being made by both Whitehead and Armstrong at about the same time. About 750 Bliss-Leavitt torpedoes Mks.1 through 3 were procured by the US Navy. They entered service between 1904 and 1906 and remained in service until 1922.Three Decades of Torpedo Development: 1908-1938
Twenty-one inch torpedoes were fine for large surface ships, but they were too heavy and too bulky for the torpedo boats, destroyers and especially the submarines of the day. Four new 17.7" torpedoes were designed to address this shortfall. The Bliss-Leavitt Mk.423 was, similar to the Mk.3, but designed especially for submarines. Mk.5 was a Whitehead design produced by Vickers and by the new torpedo factory at Newport. This torpedo could be set for any one of three speeds with corresponding maximum ranges, longer, of course, for slower speeds. The speed had to be set, however, before the torpedo was loaded into the tube thus limiting tactical flexibility. The power plant was a dry heater system using a four cylinder reciprocating engine, the last piston engine used in US torpedoes until the Mk.46. The Bliss-Leavitt Mk.6 introduced a new turbine configuration in which the wheels were horizontal. This configuration has been the most common choice for US Navy torpedo turbine systems ever since.
The Bliss-Leavitt Mk.7 was the last 17.7" torpedo acquired by the US Navy, but it was a milestone. It introduced cooling of the combustion chamber by spraying water into it in addition to the fuel and air. The resulting mixture of steam and combustion products was a better working fluid for the turbine than heated air and dramatically improved the range. Torpedoes of this type quite naturally came to be known as steam torpedoes. Another first for the Mk.7 was the use of TNT in the warhead. In addition, this torpedo could be launched from submarines or destroyers and was used later in experimental air launchings. The Mk.7 entered service in 1911 and with many modifications remained in service in older submarines through 1945. After 192224 it was the only US Navy 17.7" torpedo in service. Mark 8 was the 21" companion to the Mk.7. It was designed for destroyer launch against surface vessel and was, in particular, the standard weapon for the flush deck destroyers (DD 75 through DD 347).____________________
23 Beginning with the Bliss-Leavitt Mk.4 torpedo the practice of assigning a series of marks to each manufacturer was changed to a single series of marks for all manufactures. Thus from Mk.4 on, the mark number alone, or in a few cases the Mark and Mod., uniquely identifies each torpedo.
24 In 1922 all torpedoes prior to the Mk.7 were declared obsolete and removed from service. Only four torpedoes Mk.7 (17.7") and Mks.8, 9 and 10 (all 21") remained in service.
Just outfitting these ships required over 3000 torpedoes and this was certainly a production record until WW II. Mk.8 was also extensively modified during its long service life; Mk.8 Mod.8 was last major modification of this remarkable weapon.
Marks 7 and 8 built by E.W.Bliss were the principal torpedoes issued to US Navy ships during WW I. Five thousand-nine hundred- ten torpedoes were ordered and 1,982 delivered between 1 January 1917 and 30 November 1918. Torpedo deliveries fell behind schedule, primarily due to a shortage of forgings for air flasks, and this was used to justify a new torpedo assembly plant, NTS Alexandria, which was commissioned in June 1919. It was, however, short lived being closed in 1923. Torpedoes were not important weapons for the US Navy during WW II simply because there were few surface targets at sea after the United States entered the war.
Marks 9 through 12 were 21" steam, turbine powered torpedoes, with the same general features as described above, differing mainly in detail. Mk.9 was the last torpedo manufactured by EW Bliss and Co. and the Mk.10 was the last designed by them. Both functions were taken over entirely by the Newport Torpedo Station effective 1 July 1923 and no new US Navy torpedoes, or even piece parts for torpedoes, were designed or produced by any other US Navy establishment or industrial firm until 1940 when NTS Alexandria resumed operations and began producing piece parts. Mk.11 introduced multiple speeds that could be selected after loading into the tube. All of these torpedoes, Mks.9 through 12, remained in service through 1945. Marks 11 and 12 were pure NTS products, but altogether only a few hundred were built.
Electric propulsion was an alternative to steam. Electric torpedoes were wakeless, but their range-speed characteristics were relatively poor. Beginning in 1915 with a contract with Sperry Gyroscope Company and continuing sporadically at NTS25 after 1918 attempts were, however, made to develop an electric torpedo. These efforts led to three development torpedoes Electric Torpedoes Mk.1 and Mk.2 and the WW II Mk.20. None of these were issued as service weapons. The electric torpedo did not become important until WW II.
The trio Mk.13, Mk.14 and Mk.15, which completed development in 1936, 1931 and 1935 respectively, had a great deal in common and are justifiably famous as the workhorses of WW II26.
25 General Electric also participated in some of the NTS efforts.
26 The production figures for these torpedoes during WW II are staggering: Mk.13 17,000, Mk.14 13,000, Mk.15 9,700 also Mk.18 electric 9600 and Mk.23 (a Mk.14 variant) 9600.
The object in designing these torpedoes was to provide a modern weapon for each of the three platforms, aircraft, submarines and surface vessels. These designs were to take account of all that had been learned in the development and production of earlier weapons particularly Mks.7 through 12 and wherever possible improve performance. The development took place at NTS Newport during the period of that station's total torpedo monopoly. Furthermore, through that period NTS seems to have operated in what was almost total technical isolation and certainly a complete competitive vacuum. As noted above, from 1923 on only NTS Newport had designed or built torpedoes for the US Navy. Neither the Mk.11 nor the Mk.12, the two earlier entirely NTS designed and built torpedoes, had, however, been produced in large quantities27 or become important service weapons.
The common features of the three new torpedoes were the turbine and other mechanical parts of the propulsion system, the depth engine and gyro and the contact part of the exploders. The Mk.13 was the first torpedo developed by the US Navy specifically for launching from aircraft. It was shorter and larger in diameter (22.5") than either of the other two. Its maximum speed was lower, 33.5 k vs 46.3 k for the Mk.14 and 45 k. for the Mk.1528. The lower speed had important consequences as we shall shortly see! Also, the Mk.4 exploder used in the Mk.13 torpedo did not contain the magnetic influence feature that was deemed so important in the Mk.6 exploder used with the other two torpedoes. Externally the three torpedoes differed to suit the different platforms. The Mk.13 structure was also designed to survive an air launch from 50' at 100 k. and thus somewhat more rugged than either of the other two, however, for the higher altitude and greater air speed launches that became important in WW II accessories were required to maintain satisfactory aerodynamics and prevent damage on water entry29.____________________
27 The total production of Mk.11 and Mk.12 combined appears to have been less than 200 and almost all Mk.12. Existing Mk.12 torpedoes were issued to destroyers during WW II, but the number was insignificant compared to the 9700 Mk.15 torpedoes that were produced.
28 The only other 45+ k. torpedoes in the US inventory were the Mk.11 and Mk.12 and experience with them was limited.
29 In particular, a wooden nose drag device was used to reduce water entry speed and wooden tail fins and provided aerodynamic stability after release from the aircraft and before water entry. Both of these devices broke off on water impact.
The mechanical parts of these weapons were beautifully made but the mechanisms seem excessively complex. It is difficult to appraise this complexity without attempting an alternative design within the framework of 1930s design practice, but it is also difficult to escape the feeling that these devices are yet another example of arcane instrument engineering as practiced by BuOrd without competition from other design teams30. In their defense it must be noted that there were very few, perhaps only one (structural failure of the contact exploder), purely mechanical problems that were not quickly found and easily fixed.
What does seem to have been overlooked is the effect of increased speed on details of the hydrodynamics and on the inertial forces experienced by torpedoes. The first led to a significant depth control problem in the Mk.10 and was exacerbated by a factor of about two by the increased speed of the Mk.14. The second led to the structural deformation and attendant failure of the contact portion of the Mk.6 exploder. An entirely separate problem was the failure of the magnetic influence portion of the Mk.6 exploder. These problems, which were particularly acute in the Mk.14 submarine launched torpedo, are discussed in the next part of this series.____________________
30 An interesting comparison is that between the complex inertial ring and trigger mechanism in the early Mks.4, 5 and 6 exploders and the elegantly simple ball switch of the Mk.6 Mods.5, 6 and 10 exploders.