Post-World War II Acoustic ASW Torpedo Development
A brief history of the MK-35, MK-41, MK-43 and MK-44

By James V. Shannon
Updated 14 June 2002


During the Battle of the North Atlantic in World War II, Allied Merchant Ships were sunk in alarming numbers by German U-boats.  Winston Churchill wrote that the only time in the war that he felt ultimate victory was in doubt was during the Battle of the North Atlantic.

That battle was really the lynch pin to Allied victory.  It was a close thing.  Antisubmarine weapons were primitive and imposed severe attack restrictions on the surface ships and aircraft using them.  The US Navy was gravely concerned about this weakness in its capabilities.  After the war, they undertook a major effort to improve the Navy's submarine detection, classification and kill capabilities.  Although a number of weapons were placed under development, many were merely attempts to improve on the delivery of unguided depth charges of one sort or another.  Examples were Weapon Able, a mortar-launcher aimed by the fire control much like the turret guns of the destroyer, launching a depth charge-like bomb with improved accuracy.  Hedgehog was an aimable multiple charge spigot mortar which launched a shotgun-like pattern of contact charges.

However, a passive acoustic homing torpedo, the Mine MK-12, despite its limited capabilities, had proved effective in the latter stages of the war.  The key to antisubmarine weapons was now seen as the acoustic homing torpedo.  Once launched in the vicinity of its target, it searched for noise from the submarine.  When it located a target, it homed down that noise bearing under its own propulsion to deliver a contact hit.  So, its lethal range was expanded to the noise detection range of its acoustic search equipment.  These acoustic-homing torpedoes, like the similar anti-surface ship torpedoes used by the Germans, searched for the target by listening for its noise.  Surface vessels make lots of noise; it is inherent in the physics of their design and operation.  Submarines make noise when they are underway and that noise is proportional to their speed and depth.  But there is another way to detect targets by sound, even if they do not generate noise themselves:  Active acoustics.  Active acoustic systems work just like radar and sonar.  Send out a pulse, in this case a sound pulse, and look for its echo from the target.

The following essay is a brief history of the development of post-World War II Acoustic ASW torpedoes by the General Electric Company (GE) for the US Navy.

Torpedo MK-35

The first antisubmarine vehicle was the destroyer, which was developed before World War I.  Then, between the World Wars, as this capability was extended, aircraft were added.  Primarily, these were fixed wing patrol aircraft operating from shore locations and carrier operated aircraft, plus the blimp.  From the lessons of World War II, new thinking brought a new antisubmarine vessel into the picture:  The submarine.  Submarines have inherent advantages in that they can lay quietly in concealment, choosing the best depth for acoustic searching, and wait for their unwitting target.

This new thinking was incorporated in the requirements for a new torpedo for both surface and submarine launch.  The ideal weapon could be programmed in azimuth and depth to run out to the target area before starting to search.  It could be programmed to start its search either upward, or downward and to circle either left or right.  It could be programmed to search a specific depth of water, with a search ceiling and a search floor defining the depth strata.  It could be programmed to search either in passive mode or active mode.  These control settings were incorporated in the specifications for the Torpedo MK-35.  It also included an anti-circular feature, to keep it from turning back on the launching vessel.  This occasionally happened during the war, with disastrous results.  Its acoustic transducer was to be pendulously pivoted so that its acoustic beam would always be horizontal in order to minimize detection of non-submarine targets on the bottom or surface.

The MK-35 was to be that universal weapon, launched from either a submarine or surface vessel torpedo tube, and to be used primarily against submarines.  But it was to have a secondary role in attacking surface ships as well.  It was to be the Cadillac of torpedoes, or perhaps the Rolls Royce of torpedoes.

The torpedo MK-35 Mod-1 was designed, developed and evaluated by the Bureau of Ordnance (BuOrd) through a contract with the General Electric Company.  One of its features was its seawater main propulsion battery (actually, the battery worked equally well in fresh water, as well).  It used silver chloride and magnesium battery plates separated by glass beads.  When the torpedo was launched, it scooped water into the battery to activate it.  Such a battery has a light weight until it enters the water and floods.  This also eliminates the need for battery maintenance.  These batteries have a high power density – a great deal of power from a small, light package.

Battery-propelled torpedoes have advantages over the chemically propelled torpedoes.  Chemically propelled torpedoes must carry their own oxidizer as well as the fuel for their engine.  This adds considerably to their weight and bulk.  The electric torpedo is wakeless, thus almost undetectable by sight, while a chemical engine produces a wake of expended gasses.  In addition to a visible wake, the backpressure on the engine as the torpedo descends reduces the engine's power output and sharply decreases its fuel efficiency, thus reducing the torpedo's range and speed.  Including the equipment to compensate for backpressure to maintain power also sharply reduces the range.  In contrast, the power of the seawater battery, and hence the speed and range of the torpedo, remains constant throughout its run.  The disadvantages of the sea water battery is that it is a primary battery, cannot be switched off once it is activated and that its silver chloride plates are expensive.  On exercise runs, where the torpedo is recovered, the cost is mitigated by recovering the silver, which is converted to pure silver in the electrochemical reaction that produces power.  Shorter-range exercise runs during development, proofing, etc., can be run with a high performance, lower cost, lead-acid exercise battery.

The main motor's single rotation output was reduced in RPM and divided by a gearbox into counter rotating output for the two propellers.  With the low torque unbalance from the counter rotating propellers, vertical reference was obtained by designing the center of gravity (CG) below the center of buoyancy (CB).  The moment created by this design was called pull-around, measured by the force in pounds required to rotate the torpedo 90° in the roll plane.  Pendulous moments resulting from centrifugal force in a turn were balanced by a small difference in areas of the top and bottom rudders, creating a proportional counterforce through differential lift.  Thus, no active roll control was required, which allowed the roll gyro to be eliminated from the design, resulting in reduced cost, weight and, most importantly, complexity.

The immediate post war years were a time of swift learning as experience and rapidly advancing technologies made many new things possible.  The MK-35 Mod-1 was considered very satisfactory during the BuOrd evaluation of canned runs against stationary targets and a few runs against the target submarine USS Manta (SS-299).  Now it was to be evaluated by the Fleet's Commander - Operational Test and Evaluation Force (ComOpTEvFor).  That task was assigned to the Surface Antisubmarine Development Detachment (SurAsDevDet) at the Key West Naval Base Annex, across the slip from the BuOrd test and development facilities.  Things were happening fast in those days, and coordination was sometimes lacking.  It had been realized that the Torpedo MK-35 was being designed to communicate with the fire control in DC voltage signals.  But the new MK-102 Fire Control System with which it was to mate was being designed to communicate with AC voltage.  After a review, it was decided that the two elements of the new Sonar-Fire Control-Torpedo system would standardize on communications with AC voltage.  As it would be simple to convert the torpedo to AC compatibility in a Mod-2 version, the DC voltage MK-35 Mod 1 torpedo and the AC voltage fire control would be evaluated separately for this first series of tests.  The MK-35 Mod-1 evaluation was considered to be very successful.

The MK-35 was modified and improved and put into a development program to verify the design.  The wrinkles inevitable in the technology of the early 1950’s were identified and rectified.  The new Mod-2 went through BuOrd evaluation, declared a success, and issued to SurAsDevDet for Fleet Evaluation.

This was a new kind of evaluation program.  The sonar, the MK-102 Fire Control and the Torpedo MK-35 Mod-2 would be integrated into an overall ASW system.  Instead of canned shots against a submarine whose course, speed and depth program were known to all the participants, the destroyer would search for the submarine whose program was known only to the senior evaluation officer, a SurASDevDet lieutenant riding on the destroyer (the GE field development engineer serving as BuOrd's liaison representative rode on the submarine).  When an underwater contact was made, the sonar crew would first classify whether it was the target or an artifact.  Then the fire controlmen would derive a fire solution, set the torpedo for launch and eject it from the tube.  At the moment of torpedo water entry, marked by a grenade signal from the destroyer as well as the splash, the target submarine was free to evade in any way its captain chose.  He and his crew were highly motivated to evade the torpedo.

Many things were learned from this new kind of evaluation that crossed the traditional bureaucratic lines.  Results were ”depressingly poor compared to the Mod-1.” Actually, the performance levels of the Mod-2 were almost identical to that of the Mod-1, under the same conditions.  What was new was that the torpedo was for the first time encountering realistic combat conditions.  In addition to weaknesses in tactics, the unanticipated evasive capability of the fleet submarine target (even though still limited to nine knots submerged) made the ASW problem much more severe than anticipated.  Aiding to the submarine's evasive ability was the fact that the torpedo was very noisy.  The submarine was able to track the torpedo in azimuth and deduce its approximate course virtually from the moment of launch.  The time that it took for the torpedo to run out from the destroyer to the search enable point gave the submarine a bonus of time to take evasive action from being detected.  It was found that the destroyer sometimes needed over an hour operating at slow speed to find the target submarine, classify that target, calculate the fire control solution and fire the torpedo against the evading submarine even within the bounds of the restricted operating area.  The submarine community was heartened.  Many submarine commanders concluded their best evasive tactic was to “close in and sink the SOB while he's futzing around at low speed.” However, the results from the submariner's standpoint were also discouraging.  For them, there were too many hits!

The official score of hits on the target submarine could have been a little higher.  On one run, the attacking destroyer USS Sarsfield (DD-837) dashed into the search area and almost immediately made a contact, classified it as a submarine, and fired a MK-35 in less that 15 minutes.  The torpedo ran out to the targeted area, began a search turn, and almost immediately began an attack, as measured by the target submarine Manta's passive sonar.  The torpedo then quickly closed on the target and made a solid hit, which was heard on the sonars of both the Sarsfield and Manta.  The problem was, it didn't hit the Manta.  But it had soundly hit . . . something.  The Review Board decided to declare the run invalid.  But it was widely reported that there were “snooper submarines” operating in the exercise areas.  The unofficial discussion was whether one of them had blundered into the wrong position to spy on the exercise and been found and hit.

There were faults in the specifications for the design, as well.  For example, initially there were a number of incidents where the torpedo did not run.  These were traced to the fact that the torpedo was equipped with a ready-safe switch on the afterbody that made ready or safed the torpedo system and a second switch on the battery section which prevented inadvertent activation of the battery.  Both switches were to be manually set to the ready position when the torpedo was loaded in the torpedo tube.  But the destroyer crew, who were less experienced than the development technicians of the BuOrd evaluation, were overlooking the second switch.  The second switch was deleted from the design and “material failures” declined sharply.

On the record, the evaluation was a qualified success.  A small quantity of MK-35 Mod-2 torpedoes was manufactured and issued to the fleet where most of them eventually languished on destroyers whose crews had little knowledge about their uses or capabilities.

But the program was a success in the sense that everyone involved learned many valuable lessons that led, sometimes torturously, to the success of the slightly later MK-37 surface and submarine launched ASW torpedo and to the Fleet and NATO standard MK-44 surface, air and rocket launched ASW torpedo.

Torpedo MK-41

Any hopes of a universal torpedo that included airdrop capability were quickly dashed as the MK-35 initial design progressed.  General Electric engineers proposed an alternative airdrop torpedo configuration, based on many of the MK-35 components and subsystems, which was accepted by the Navy.  This Torpedo MK-41 design was a 21 inch diameter weapon that was shorter, lighter and more rugged than the MK-35.

Previous aircraft launched torpedoes had a tendency to skip off the water surface at water entry, often spoiling the run.  Wooden assemblies, a “pickle barrel” around the nose and plywood fins around the tail that broke away at water entry, were devised to eliminate this problem.  For the MK-41, a flat nose was designed to “dig in” when it entered the water and a parapack was used to stabilize the weapon attitude along the flight path during the airdrop.  This required a rigid flat acoustic transducer face, instead of the oil filled rounded nose of the MK-35 that enclosed the pendulous transducer.  Essentially the same seeker electronics and hull section were used with modifications to the search and attack control assembly.  No gyro was required.  No pre-enable runout was needed, so a new battery section with a lower capacity battery was designed.  Essentially the whole afterbody and tailcone was used intact.

Homing characteristics, acoustic search and attack ranges, and torpedo speed and depth capability were essentially the same as the MK-35.  Field development was progressing satisfactorily.  The routine method of launching during this development period was to drop the weapon over the side from a rack on the torpedo retrieval boat.  This suggested it could be launched from an ASW surface ship the same way.  Thus, it could be used by even small ASW vessels for surface launch much like a depth charge.  However, when launched this way, if the pitch reference sensor was not set in a certain way, the torpedo could attempt to jump from the water.  The record leap was one that went directly over the 38-foot torpedo retriever boat.  This was obviously something that would have to be changed.

But the MK-41 was large and heavy.  ASW helicopters were in the offing and the MK-41 was unsuitable for use by them.  Other ASW aircraft and blimps would profit greatly from a smaller and lighter weapon, as this should mean that more weapons could be carried.  By 1950, General Electric engineers had determined that a small 12.75-inch homing torpedo with similar homing capabilities was feasible with a sacrifice in speed to 14 knots and use of a smaller warhead.  Their proposal was accepted as the MK-43 Mod-0.

The MK-43 design began to prove itself against pre-guppy submarine targets in field development.  Although there was some controversy about the effectiveness of the smaller warhead, in 1952 the MK-41 program was canceled in favor of the small MK-43.

Torpedo MK-43

The torpedo MK-43 Mod-0 was a 12.75-inch diameter weapon.  That diameter was determined by the filament-wound fiberglass tubing being used for electric transformer winding cores by GE's Transformer Division which was located about a mile from the GE Naval Ordnance Plant.  GE's ordnance engineers checked it for external pressure capability and found that it could meet the depth specifications for the MK-43.  This tubing was in production and was therefore immediately available.  It also had the advantage of being inexpensive.  This tubing was 12.75-inches in diameter.  That incidental fact wound up setting the standard diameter for the lightweight airdrop torpedoes MK-43, MK-44, and MK-46; and for the triple-nest torpedo tube system MK-32 used on surface ships

The MK-43 was to have the same acoustic system characteristics as the MK-35 and MK-41.  The electronic system was redesigned using miniature vacuum tubes and other components that had been developed for smaller lightweight electronic equipment, giving it similar acoustic search and attack characteristics.  The run controls and attack computer were based on the MK-41 characteristics.  A new, smaller seawater battery was designed as well as a new afterbody for the electric motor, gearbox, and rudder and elevator mechanisms.  A single propeller was used, as at the lower speed of about 14 knots, the propeller torque could be countered by skewing the fins.  Simple cruciform fins replaced the shroud ring used in the MK-35 and MK-41 torpedoes.  The CG was again below the CB, and centrifugal rolling force in turns was compensated by differential fin areas.  So no gyro was included in the design.

The helicopter community eagerly awaited the lightweight weapon.  Helicopter technology was progressing rapidly, although not yet at a point able to provide a reliable weapons platform.  Helicopter airdrop torpedo exercises were carried out by two helicopters.  Their skins were removed to reduce weight to provide payload and enough endurance for one to fly from Key West to the exercise area offshore, find the (marked for them) position of the target, and call in the kill helicopter.  The kill helicopter would then fly out and drop the weapon.

The MK-43 Mod-0 performance was satisfactory, but it had a competitor.  The Brush Manufacturing Company had been given access to the MK-35 basic design and performance by BuOrd and tasked to develop the Torpedo MK-43 Mod-1.  Its design actually was more of a miniaturized airdrop version of the MK-35 than that of the MK-43 Mod-2.  In contrast to the emphasis on functional technology of the pioneering Mod-0, the Mod-1's designers were tasked to follow the functions developed in the GE programs while designing for minimum cost.  After the two weapons were evaluated, BuOrd selected the MK-43 Mod-1 for production and service issue.

The more rugged Torpedo MK-43 Mod-0 was relegated to being the payload for development of rocket propelled torpedo launching, starting with the ASROC program.

There was discussion among the submariner community questioning whether either Mod hit submarines in trials and exercises with sufficient force to activate the exploder to detonate the warhead.  The difference in speeds, even for a pre-guppy submarine, was small and the torpedo power supply was sometimes exhausted while tail-chasing a fleeing submarine.  Against a guppy submarine, the weapon was marginal.  At best, there was only one realistic method of obtaining a hit, which was to launch the torpedo from a position ahead of the submarine.  That was a difficult aspect for attack, further complicated by the uncertainty of aircraft attackers being able to accurately launch the weapon within the small area from which a successful attack was possible in a real situation.

Against future high-speed streamlined submarines based on the USS Albacore program, the MK-43 was completely outclassed.  However, the principle of a small lightweight weapon suitable for helicopters and giving other aircraft the ability to carry multiple weapons was proven, as was the principle of launching these smaller weapons from surface ASW vessels.

Torpedo MK-44

To overcome the deficiencies of the MK-43, BuOrd established two new programs:  One at the Naval Ordnance Test Station - Pasadena (NOTS-Pasadena), California for the Experimental Torpedo EX-2A; and the other with the General Electric Ordnance Department, Pittsfield, Massachusetts for the EX-2B.

The EX-2A was to be electrically propelled by a counterrotating motor, with no gearbox used.  The EX-2B was to be gas turbine propelled using a gearbox to reduce the high RPM of the turbine and divide its output to contrarotating propellers.  The acoustic and attack control designs were to be based on different approaches being developed by the competitors.

The GE acoustic and control system was mounted in a 19-inch swimout private venture vehicle that had examined extreme low cost designs, called Shoestring, and search and attack development runs were begun from the Key West Test Station.  In addition to stationary targets, this design was run against a MK-35 that had been converted into a mobile target whose speed, course and depth could be preprogrammed.  Unlike previous designs, the torpedo search system had two different ping transmission rates, switched to the higher rate as the range to the target closed.  Development proceeded satisfactorily.  Design of the turbine engine package was progressing when an accident with the specified normal Propyl Nitrate (nPN) monofuel (a single fluid containing both fuel and oxidizer) in a Navy facility halted its use.  GE was given a very short time to convert the EX-2B to a conventional seawater battery propulsion system or its program would be canceled.  Designing a sea water battery was a straightforward and quickly implemented task.  But a frantic search was launched for a suitable and available electric motor.  One manufacturer responded with their design for a jet engine starter motor from a failed aircraft jet engine design program.  One was found in the Pawtuxent Naval Station scrapheap, set up in the manufacturer's laboratory, and demonstrated amid billowing smoke and sparks.  It promised to be suitable and was quickly modified to become the basis for the final design.  A converted torpedo was demonstrated in water runs.  The EX2B specifications were converted to electric propulsion and the program continued.

After laboratory testing of the high power rated, very light counter rotating gearbox was successfully completed, the design engineer consulted an oil company laboratory about suitable AN (Army-Navy specification) lubricating oil.  They replied with a letter giving a long AN specification number.  Unable to locate that oil in the available engineering office documents, he called to ask where he could obtain samples.  The oil company engineer asked, “Is one of our gas stations nearby?” Told yes, he said, “Go over there and ask for our SAE-30 motor oil.”

The NOTS-Pasadena computer simulation facility was tasked by BuOrd to evaluate the homing controls of both competitor's designs.  After completing the EX-2A evaluation, a crisis developed for the EX-2B as unsatisfactory performance was reported.  Two GE engineers rushed to California to compare the results being obtained in the simulation with water runs made with Shoestring.  A quick review showed a missing wire in the prints that signaled the shifting of the ping rate as range closed.  It was quickly installed on the torpedo equipment being used in the simulation and the simulated and water run data began to show very similar results.  The simulation facility was made up of two rooms full of vacuum tube technology electronic racks (a state of the art analog computer surrounded by extensive specially designed electronic equipment), a large x-y plotting table, and a hydraulically driven table which moved the torpedo electronic panels dynamically in pitch and yaw in response to search and attack commands.  A computer engineer came in about 4:00 AM to start up and calibrate the equipment so that simulation runs could begin around 8:30 AM.  The simulator was then run continuously until about 9:00 PM, or until it went out of calibration, or until something failed.  That was the state of the art of complex computer based simulation in the early 1950’s.  This was developmental equipment, expected to be touchy.  But the MK-102 Underwater Battery Fire Control systems installed in the evaluation destroyers USS Sarsfield and USS Saufley (DD-465), once up, calibrated and running, were never shut down.  It was said that the on-board spares and support inventory included one Manufacturer's engineer.

At least the EX-2B simulation was not plagued with dynamic table problems, as was an earlier project.  That torpedo used bang-bang steering, where the rudders and elevators banged continuously between their full deflection positions.  The steering input held them over at full deflection for a given time, instead of to a deflection angle, proportional to the turning rate commanded.  That meant a cheaper and simpler actuator design could be used.  As the simulation table was highly responsive to rudder position rather than just the average position, this put a heavy load on the hydraulic system.  There was a sign posted by one of the technicians near it that read,

“'Twas brillig, and the slithy toves
Did gyre and gimbal in the labe
All flimsy where the pressure joints
And the hydraulic lines outgave.”

(Apologies to Lewis Carroll)

The simulator runs were shown to so accurately replicate our water runs that we asked to use their simulator project to refine some of the attack control parameters.  The NOTS-Pasadena simulator staff were delighted to accommodate that effort, which they then used to show doubters the value of their simulation efforts.  They made a very favorable report to BuOrd on our system and the crisis evaporated.

The first runs of the EX-2B torpedo in the water showed a serious problem in the hydrodynamic design.  The control surfaces were very much less effective than the design promised and the torpedo could not be satisfactorily controlled.  Another Navy laboratory and their University laboratory consultant did the hydrodynamic design.  Based on tests they had carried out in a water tunnel, they believed that if the control surfaces were placed inside the shroud ring rather than abaft of it, they would be much more effective because of the “end-plate effect.” We quickly theorized that this was not so, that the shroud ring straightened the flow the control surfaces deflected, canceling much of their effectiveness.

An engineer and some equipment was rushed to the Navy Large Scale Water Tunnel Facility at Pennsylvania State University, where testing showed that this was true.  The circular configuration of the shroud ring performed totally different from flat end plates.  There was no time to redesign the tailcone and actuators to move the control surface shafts aft, outside the shroud ring.  A compromise redesign of the control surfaces was evaluated and proved acceptable in tests and water runs to resolve the problem.  Their span was sharply reduced and the chord was lengthened to place an effective area outside the shroud ring.  It was an inelegant but effective solution.  BuOrd held a shoot-off against stationary and target submarine targets.  The GE EX-2B design won and was designated the Torpedo MK-44 Mod-0.  General Electric became the Design Cognizance Agency to production design the torpedo, and NOTS-Pasadena was designated Torpedo MK-44 Technical Director for the Navy.  At that time, I was at Canaveral with my own problems on the Polaris Program and am fuzzy on exactly what happened.  The CNO accepted the MK-44 Mod-0 and it was put into production.  After the first several successful Polaris shots with guidance on board (I wound up reminding veteran Canaveral launch engineers about check lists after a series of their failures before our guidance phase.  Complacency can be a terrible problem), I was called back to the torpedo program to trouble-shoot problems in proofing at Keyport and became Design Cognizance Technical Director.

The MK-44 was put into production at the Navy's Forrest Park Ordnance plant in the Chicago, Illinois metropolitan area.  The torpedoes were proofed at Naval Torpedo Proofing Station-Keyport, Washington and issued to the fleet.  There were a few things that could be improved, and GE's Key West Test Station was conducting development runs in the Florida Straits when the next to worst thing that can happen to an acoustic homing torpedo happened.  Extraneous noise, that is sound that is not coming from the target or from a noise source on the torpedo or from any expected target, interferes with the torpedo's ability to detect and attack the intended target.  This noise had characteristics we had never before observed.  It came in spikes just like the echoes expected from the target, but often in two closely spaced spikes where we would expect only one.  It varied smoothly in volume as sound would from a radio when you turned the volume up and down.  The indicated rate of closure on the sound source varied, but was often much faster than the torpedo could run!  Sometimes the closure rate indicated speeds of hundreds of knots.  It continued unchanged for a time after the torpedo stopped running and its sonar was turned off.

We spent hours on the telephone between Key West and our home plant in Pittsfield, Massachusetts, puzzling over the cause, suggesting tests, and analyzing results.  We were completely puzzled.  Then, our station manager in Key West woke up one morning to find a .50 caliber anti-aircraft machine gun set up in the empty lot just outside his bedroom!  The Cuban Missile Crisis had begun.  All R&D operations in the Florida Straits were immediately canceled.

Our program was moved to the Keyport Washington Naval Station.  There, with the first-in water runs, the absolute worst thing that could happen, happened.  The noise disappeared and we couldn't find out why!  The changes being developed were completed, proven in water runs, and incorporated in the MK-44 Mod-1.  The Mod-1 became the standard airdrop, small torpedo surface, and rocket launched (ASROC at the time) acoustic antisubmarine homing torpedo for the United States Navy.  It was adopted by NATO.  Production began in Canada, Britain, Italy, and Japan.  Allies in Asia adopted it.  Australia made it the torpedo payload for their IKARA rocket launched system.

But nuclear propelled submarines with their streamlined hulls and high-sustained underwater speed capabilities threatened its effectiveness.  The Navy had initiated a new program to develop a higher-speed torpedo, the Torpedo MK-46.  GE continued its Design Cognizance role until underbid by another company for second source manufacturing.  GE then recommended to BuOrd that it be transferred to the successful bidder.

GE transferred its torpedo development resources to the Polaris Fire Control and Guidance Program where they were associate contractor in the Navy's highest priority program.  Then, about two years later, the former Design Cognizance Technical Director who had become a member of the staff of GE's Technical Military Planning Operation (TEMPO) think tank in Washington, DC, working on antisubmarine system studies, attended an acoustic conference.  At that conference, two researchers from Pennsylvania State University described their acoustic research program in the Florida Straits.  To lighten up this arcane presentation, they told a sea story.  Some days the researchers had to stop work and haul in their gear and go ashore because of porpoise.  It seemed that the porpoise loved to gather around the transducers and mimic their transmissions.  The researchers showed a slide which showed the same extraneous noise that had plagued the MK-44 program – and had then gone away with a change in location.  Tursiops truncatis, the common dolphin, turned out to be the elusive culprit.

At the next break, the GE engineer asked how they were sure it was porpoise.  They replied that the porpoise had followed their transducers right to the surface, talking to them all the way.  The GE engineer told them of his own baffling experience with torpedoes that he had now deduced had been caused by those same noisy porpoise.  They all agreed that the porpoise had gathered at the transducers to ask when their talkative, silvery, frisky little friends would be coming back to play.

Biographical Note

James V. Shannon served several years as a Merchant Marine Radio Officer, gaining experience that was to serve him well, while earning his BSEE at Southern Methodist University in 1951.  For the succeeding twenty years, he served as a Field Development Engineer, Systems Engineer, Torpedo MK-44 Design Cognizance Technical Director, and Systems Analyst in Naval Weapons at General Electric.  This time included almost two years as Launch Planning Engineer - Fire Control and Guidance on the Polaris Program with responsibility for setting up the facilities and getting the first Polaris missiles carrying guidance packages successfully launched.  In 1972, he transferred to the industrial capital goods industry to help apply the control capabilities of electronic systems to commercial products, with emphasis on medium and heavy truck powertrains.


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