The Great Torpedo Scandal: Lessons Learned

"Submarine” and “torpedo” are subjects, which go hand in hand, and a history of one must of necessity include a study of the other. The submarine was invented for the express purpose of carrying an underwater demolition charge into battle, and the modern mobile torpedo evolved as an engine designed to deliver the charge to the target.

Obviously, torpedo performance has a direct influence on all submarine operations. It is up to the submarine to locate the target, to adjust the torpedo appropriately, and to unleash it at the proper time. Once sent into action, the torpedo must “carry the ball.” Let it fumble, falter, or fail, and the whole play goes askew. Such failure may cost the submarine its life. It goes without saying that battles as well as submarines might be lost through torpedo failure. The United States (US) submarine force entered World War II with a faulty weapon, and it was not until late in 1943 that this serious condition was remedied.

Weighing approximately one-and-one-half tons, with an effective range of over 9,000 yards, the MK 14 torpedo was, in effect, a small robot submarine. Ejected from the torpedo tube by compressed air, the weapon could level off at a pre-selected depth, and follow a curve to seek out a predetermined course to intercept the target. Steam, generated by forcing a spray of water through a torch of burning alcohol, supplied motive power. Steering was controlled by means of a gyroscopic mechanism. A delicate hydrostatic device, reacting to water pressures, governed depth control. The explosive carried in the torpedo warhead contained about a quarter of a ton of TNT. The blast was detonated by an exploder mechanism which worked by contact (direct hit on the target) or by magnetic influence when the torpedo passed through a steel ship’s magnetic field. Certainly the torpedo with which US submarines entered the war was a remarkable weapon—one of the most complex engines of destruction ever produced. It had one drawback, however. All too often it didn’t work.

The weapon would variously make circular runs, porpoise, run “cold,” or sometimes even refused to run at all. These malfunctions were infrequent, and could generally be attributed to personnel errors—poor preparation or faulty adjustments. More baffling were the defects inherent in the design of the torpedo and the exploder mechanism.  Specifically, the torpedo ran deeper than set depths. They exploded prematurely, sometimes close to the submarine immediately after arming, sometimes near the target, the blast simulating a hit, but not near enough to inflict crippling damage. Or they might be duds, striking the target, and failing to explode.

Each flaw concealed the next, making it impossible to detect and correct all of them simultaneously. The deep-running torpedo hid the premature skeleton in the closet, and it was not until the deep-running was corrected that prematures rattled out into the open.  Prematures were a product of the defective magnetic exploder. When that device was inactivated to solve that class of failure, the dud emerged as a major problem.

Most baffling of all was the fact that these torpedoes, when they did work, ran through their paces to perfection and left nothing to be desired. They sank enemy ships…thousands of tons of them, and thus masked the tracing of the flaws.

The officers in the submarines who staked their lives on the performance of the torpedo were up in arms against the doctrinaire and bureaucratic inertia that refused to recognize or properly diagnose the problems, thus impeding the cure. Several top-level officers of the ordnance organization ascribed all torpedo faults to errors of the operating personnel, and chose to define “dud” as a skipper’s alibi to explain his miss. It was only after the forces afloat out in the fleet, stepped in to solve the problem that the submariners were supplied with a weapon worthy of their skill.

The MK 14 torpedo, 21 inches in diameter and 21 feet in length, had two speed adjustments. It could be fired with a speed of 46 knots to a range of 4,500 yards, or, in low power, with a speed of 31.5 knots to a distance of 9,000 yards. The low power setting was rarely used for it afforded the target ample opportunity to evade. The warhead was later increased in size from the original 507 pounds of TNT to 668 pounds of Torpex. 

The Mark 6 exploder was an extremely complicated mechanism. Its production was classified Top Secret. It was not issued to submarines until the summer of 1941, and even then, only commanding officers and torpedo officers were allowed to know how it functioned. It soon became clear that torpedo men would also have to be informed. The secret was held so close that at the beginning of the war, there was no operational experience with the device, and it, rather than the torpedo itself, turned out to be the arch villain in the melodrama.

Training exercises further compounded the problem. At $10,000.00 apiece, the Navy could not afford to lose any of the weapons. An exercise head was employed. Filled with water instead of explosive, it was designed to expel the water at the end of the run so that the torpedo would float and be recovered. Thus, neither the warhead nor the exploder would be tested.  In addition, to prevent damage to the target ship, the torpedo was set to run deep so that it passed under the target. The future problems were completely masked.

The deep running torpedo was the first defect to surface….no pun intended.  Frequent reports of torpedoes running deep and passing under the target without detonating were received and sent on to the Ordnance Bureau. A lack of response prompted Admiral Charles Lockwood, the Submarine Force Commander, to conduct his own tests. In June, 1942, at Albany, Australia, USS Skipjack fired a torpedo, set for ten feet, at a net 850 yards away. The torpedo cut a hole in the net at a depth of 25 feet. Several more torpedoes were fired with similar results. The tests were reported to the Ordnance Bureau which, despite a report of identical torpedo performance from Pearl Harbor-based submarines, rejected the results based on their assessment of torpedo trim.

Admiral Lockwood was not to be denied. Australia was too close to the firing line, and credible commanding officers (COs) were returning from patrol to relate tales of deep running fish. The admiral ordered the modification of the exercise head to eliminate the Bureau of Ordnance criticism of test torpedo trim, reran the tests, and again reported consistent deep running results. Meanwhile, back in Washington, Admiral King, Commander-in-Chief of the US Fleet, wrote a letter to the Chief of the Bureau of Ordnance citing the defective torpedo performance and directing that it be corrected. That got their attention and soon a directive was issued acknowledging the problem and prescribing a new depth setting relative to the draft of the target. But the bureaucratic fumbling had already damaged the submarine campaign. Hundreds of hours had been expended on fruitless approaches. Targets had been missed. Some of the pioneer captains, discouraged by their failures had asked to be relieved, and many thousands of dollars of scarce ammunition had been wasted. But let’s move on to the other problems with the weapon….

TNT is an explosive not easily detonated. Under normal circumstances, neither fire nor shock will cause it to explode…it must be acted upon by a detonation wave.  In the torpedo warhead, this wave is produced by the firing pin striking the primer cap, which in turn sets off the detonator positioned within a cavity of a booster charge. The explosion of the detonator sets off the booster. The booster produces the detonation wave which causes the TNT to explode. So not one explosion, but a series of three which occur rapidly creates the final blast.

The MK 6 exploder was designed to release its firing pin either upon contact with the target, or upon passing through the target’s magnetic field. Theoretically, a close miss could be as fatal as a strike, and under some circumstances more damaging.

The exploder mechanism contained another important feature—a device which disarmed the torpedo for safe handling. In the unarmed condition, the detonator was withdrawn from the booster cavity, preventing any accidental shock, concussion, or jolt from setting off the booster and thus the main charge. When the torpedo was fired, its rush through the water activated a spinner, which operated a chain of gears that moved the detonator into the booster cavity. This was accomplished after a run of about 450 yards. The torpedo was then armed. During the arming run, several delayed-action switches closed, vacuum tubes were warmed up, and the exploder was ready.

The 450 yard run was more than enough to protect the submarine. It allowed the torpedo to seek its run depth and settle out on its course to the target…that is, it calmed down and hit its stride.

Another contrivance now came into play—the anti-countermining device—designed to prevent the torpedo from being blown up by a nearby explosion such as might occur when several torpedoes were fired in rapid salvo. The firing pin was locked when a pressure wave greater than a fixed level was experienced. 

So now the torpedo is set to explode by either direct contact or by passing through the target magnetic field. But it was not to be, and in the first battles of the war, the American submarines failed. Twenty-eight submarines participated in the Philippine defense. At Lingayen Gulf, only one Japanese transport was sunk out of an invasion fleet of more that 80 ships. The situation was agonizing, typified by the record of USS Sargo…13 torpedoes fired for zero hits. Morale was at an all time low, generated by the unexplained miss caused by erratic depth performance, or failure of the torpedo to explode.

Less sinister, although equally baffling, was the “premature”—the torpedo that exploded too soon. When a premature blasted the water, there was no mystery about what had happened.  “Why” might remain unanswered, but it could generally be assumed that it was the fault of the torpedo.

The premature was dangerous, potentially far more dangerous than a miss. If the blast occurred a moment after firing, the submarine could be lost. Prematures endangered our submarines in another manner…they warned the enemy of the submarine attack, and revealed the submarine’s presence, subjecting it to counter-attack. Prematures probably contributed to the loss of one or two American submarines.

The extent of the premature problem was not realized until after the depth control difficulty was resolved. When running deep, torpedoes were unaffected by the action of the surface waves. When the torpedoes began to run at the prescribed shallower depths, the motions of the sea or surges in the torpedo power plant sometimes activated the delicate exploder and caused a premature.

The magnetic exploder also caused prematures. When set to run at a depth which was less than the draft of the target, the torpedo entered the horizontal component of the ship’s magnetic field some distance from the ship’s hull. Under certain circumstances, the exploder would activate and the torpedo would detonate about 50 feet from the side of the ship. As seen through the periscope, it looked like a perfect hit. The explosions were perfectly timed, and an eruption of water directly in line with the target, obscured the vessel from view. More than one Japanese ship was found to be undamaged after its sinking was reported by a submarine skipper who had been deceived by a premature. 

This problem persisted until well into 1943, and as one can imagine, prompted considerable correspondence between the submarine forces and the Bureau of Ordnance.  As the previously secret device became more well known, many were the theories and suggestions for its improvement. Several minor changes were made, and the fleet torpedo shops ensured that each mechanism was submitted to exhaustive tests before being issued to a submarine. Still, the weapons failed.

The Bureau of Ordnance recommended new settings and new geographic restrictions. Finally after some heated exchange, Admiral Nimitz, Commander-in-Chief, Pacific Fleet (CINCPAC), ordered the magnetic exploders inactivated on all torpedoes.  That satisfied Admiral Lockwood, the Sub Force Commander. However, Admiral Ralph Christie, Commander, Submarines Southwest Pacific, directed that the magnetic feature be retained in his force, and specified depth settings for various classes of targets. By an oddity of the fleet organization, Christie was not subject to CINCPAC’s directive. His submarines continued to experience prematures, and it was not until March 1944, that Admiral Christie, in the face of his boats returning unsuccessful, ordered the magnetic feature deactivated.

Now, with the magnetic exploder mechanism out of the picture, the submariners had no reason to doubt that the contact mechanism was anything less than reliable.  Although less complex than the magnetic device, the contact device was still an intricate mechanism. And it was at this point that the dud reared its ugly head. Boat after boat returned to report close range attacks in which their weapons failed to detonate…they could hear the torpedoes hit the hulls, and not explode.

Admiral Lockwood had had enough. He decided to dispense with the unheeded radio dispatches, and to tackle the torpedo problem himself. His first act was to order the firing of two torpedoes against the submerged cliffs of Kahoolawe Island. One of the two proved to be a dud.  It was recovered and very carefully examined. The technicians found that the exploder mechanism had released the firing pin, but the pin had not hit the primer cap with sufficient force to set it off. What happened next was an exemplary demonstration of what could happen when a complex technical problem was presented for analysis to a group of able minds, no longer hindered by a blanket of secrecy. All the available talent at Pearl Harbor joined in a cooperative effort to solve the problem. 

One member of the group devised a unique test procedure. Warheads loaded with cinder concrete in place of Torpex, but equipped with exploders, were dropped on a steel plate from a height of 90 feet. This duplicated the forces generated by a torpedo when it struck the side of a steel ship. Seven of the first ten warheads dropped duplicated the performance of duds by failing to explode. Seven contact duds out of ten!! And the war was already in its twentieth month!

Analysis showed that the firing pin would release, but it would strike with insufficient force to set off the primer cap. If, however, the steel plate were set so that the warhead struck it a glancing blow, the exploders invariably functioned properly. This explained why some ships were sunk by torpedoes which struck them glancing blows at the turn of the keel, or against the side, whereas solid, normal hits might fail.

The inquiry then focused on the firing pin itself, a mushroom shaped device weighing several ounces. When released, spring action forced the pin to move at right angles to the torpedo axis. Two guide studs controlled the direction of motion which brought the pin into contact with the firing cap. The problem centered on the fact that the force of deceleration when the torpedo struck the target was such that it produced frictional forces which the firing spring was unable to overcome. The solution: produce a modified firing pin whose weight had been reduced to the bare minimum, thus lessening the friction on the guide studs. It worked!

On September 30, 1943, USS Barb sailed from Pearl Harbor for patrol carrying 20 torpedoes with the modified firing pin. By mid-October, the submarine base and the tender had produced enough of the modified pins so that all boats were so equipped.

In summary, at the beginning of the war, the MK 14 torpedo ran ten to eleven feet deeper than set, had a tendency to premature, and frequently failed to explode even after striking the target. Almost two years later, all of these defects had been detected and corrected in the fleet, by modifying the procedure for calibrating the depth setting mechanism, disconnecting the magnetic feature of the MK 6 exploder, and modifying the design of the MK 6 firing pin mechanism. Thus, the submarines finally had a reliable torpedo which could have been realized from the beginning if the pre-production testing and post-production proofing by the test firing of torpedoes with warheads attached had been more comprehensive. The scandal was not that there were problems in what was then a relatively new weapon, but rather the refusal by the ordnance establishment to verify the problems quickly and make appropriate alterations.

The effect of these defects is summarized by a consensus of those submariners who fought the war:

“The war would have been foreshortened and many American lives saved had a reliable torpedo been available from the beginning…the costs to the United States war effort in lives, dollars, and time remain incalculable.”

Only after significant cost to the war effort did operational forces out in the fleet prevail over the entrenched Washington technical bureaucracy. If the “lessons learned” from that bitter internal conflict of 60 years ago are lost, there is great potential for repeating history. In today’s acquisition world in which the “push” of exploding technology is combined with a strong “pull” from the field for solutions to the demands of the new forms of warfare, the stage is set for delivery of improperly conceived or inadequately tested weapons systems.

Under the guidelines of the Defense Department’s “Transition” movement, proposed systems must survive examination of purpose and intended employment. If not suited for the new warfare environment, then despite jobs to be lost or dollars already invested, the system must be stricken (e.g. the Comanche helicopter). And certainly, no system should be fielded without exhaustive (and successful) testing against realistic targets. The temptation to send marginally performing weapons into battle is a disservice to our troops on the battlefield (e.g. the Patriot anti-missile system in the first Gulf War).*

The performance of our weapons and combat control systems should be as close to perfect as our industrial engine can produce, and the test and evaluation organizations can bless.  Anything less is unacceptable! The current pace of warfare will not tolerate a repeat of the two-year torpedo scandal.