In 1920 The Navy Department’s General Board urged an examination of its submarines because of serious problems it was having with new engines for S-Class submarines authorized in 1916 which were then entering service. Only two companies, Electric Boat’s subsidiary, the New London Shipbuilding and Engine Company (Nelseco) and the BuschSulzer Company were building submarine diesels. New, 8 cylinder, 600 hp Nelsecos (based on the previous 6 cylinder, 500 hp models in the 0, L and R Classes) and 6 cylinder, 900 hp Swiss-based Busch-Sulzers went in these early S-Boats.
The General Board’s concern also arose from the inability to replicate the much higher output and more reliable German submarine diesels. 2 In frustration the Bureau of Engineering reverse-engineered two German engines, the M.A.N. (Maschinen- fabrik-Augsburg-Nuernberg), 6 cylinder, 1,750 hp, and the M.A.N. 10 cylinder 3,000 hp engines. In 1922 the Navy began building a Bureau clone of the 6 cylinder model to replace Nelsecos in some of the S-Boats. By 1924 the Lake Torpedo Boat Company had failed and the BuschSulzer Company stopped producing diesel engines for use in submarines. This left Nelseco as the sole private company to build submarine engines.
At the same time, the Navy moved ahead under a 1914 Congressional authorization to build fleet submarines which were intended to have surface speeds equivalent to that of cruisers and battleships. The gap between maximum submarine surface speed with Nelseco engines and battle group surface speeds rendered the term, fleet submarine, meaningless. Nevertheless, Electric Boat forged ahead to produce an advanced submarine design. These new boats were to have Nelseco, 6 cylinder engines that were designed to producer hp at 375 rpm.
Test stand troubles encountered are not known, but they began in earnest when installed. With 4 engines driving two screws, two engines were paired longitudinally with a clutch inserted between them. Between the after two engines and their propellers were another pair of clutches and the motor/generators to make a total twin drive shaft length of almost 100 feet. Little thought had been given to torsional vibrations inherent with this arrangement.
The first American T Class submarine, the T-1, (SS-52), was launched with high expectations. Trials at sea immediately revealed serious vibration problems resulting from drive shaft length and coupling of engine crankshafts. At rated speed on all four engines, torsional vibrations were so severe, linkages snapped and piston cooling piping parted. These problems were in addition to high pressure injection air compressor failures. The diesel engineers did what they could to redeem their design, but in the end, the operation of the Nelseco diesels in the T Class boats could only be accomplished by either taking the forward two engines off line by de clutching them or by reducing the RPM of the coupled engines to an insufficient power level. This rendered the surface speed of the T Class boats far below the minimums for fleet operations. The maximum surface speed using just the two aft engines was about 15 knots.
Three T Class submarines were built and during the 1920s the three boats struggled to improve their performance. T-1 was decommissioned after only 20 months of service, during which time it failed to join the fleet. The T-2 lasted 18 months until July of 1923 when it too was decommissioned. The T-3 was similarly fated but was resurrected with Bureau 10 cylinder diesels based on the M.A.N. 3 diesels, but she too was finally decommissioned in July of 1927.
Although these submarines and their ill-fated diesels enjoyed short life spans, they and the large, interim V Class boats pioneered what became the American fleet submarine of the Second World War. Even so, the old S Boats with their Jess than satisfactory engines would be forced to serve on war patrols or as training boats until they could be replaced. Thirty-one of these remained in commission at the outbreak of war.
The first of the ocean spanning fleet submarines with General Motors (Cleveland/Winton) V-16 diesels was commissioned in 1935. This evolving design, along with the Fairbanks-Morse 8, 9 and 10 cylinder in-line, opposed piston, twin crankshaft engines (built under a Junkers license) both went through their own 4 growing pains which have been well documented.
A third engine also powered early Second World War submarines. It was the Hooven Owens Rentschler, or H.0.R, 8 cylinder engine, the first of which went into the Salmon (SS-188) in 1938. 5 Ensuing engines were 9 cylinder models of 1535 hp at 700 rpm. The H.0 .R was two stroke, like the GM and FM submarine engines, but the H.0.R engine was distinctive in being double acting. This engine’s power to weight ratio was the best by far of the three authorized designs, but this advantage was bought at a price. Having a combustion chamber on both the top and bottom of the pistons meant every stroke was a power stroke. A piston rod rigidly attached to the piston passed through a sliding seal at the lower end of the cylinder. The rod’s lower end was attached to a vertically sliding cross head which anchored the top end of a conventional connecting rod. This design had long been used on large steam and diesel engines. Unfortunately, it was not yet a suitable submarine engine. Twenty boats had these, and their record was dismal with mechanical, sealing and heat related problems. Engine men and Machinist Mates had their hands full in makring repairs to engines and in particular to the internal gearing. A case in point was the experience of USS GUNNEL (SS-253).
In November of 1942 the boat was underway to its destination in England. The journey was characterized by the enginemen’s frustration in trying to keep the H.O.R. engines running. The name of the engine lent itself favorably to the profanity of those in the engine rooms. The following was taken from, ” USS GUNNEL (SS-253) First War Patrol” by RADM Joe Vassey and Mr. Jim Lavelle which appeared in the July, 2007 issue of THE SUBMARINE REVIEW.
“The engine casualty became apparent when an unusual noise was heard in the after part of No. l engine. It was immediately secured by the engine room watch. The control room crew was alerted to the seriousness of the problem when Chief Motor Machinist Mate E. W. Murphy passed through their station on his way to see the Captain. It was clear from Murphy’s grim expression and Jack of his usual banter that whatever he was holding in his hands, cupped together in front of him, represented some major casualty in the engine room. It would soon be learned that Murphy was carrying pulverized metal from Number 1 main engine.”
All four of Gunnel’s H.0.R. main engines suffered casualties that could not be repaired while at sea. The worst of these was the stripping of gear teeth which was later attributed to micro-cracks in the casting of the gears. Gunnel made its way to England making 2.5 knots on the surface using its auxiliary engine. Upon reaching port the crew made extensive repairs using parts flown to England. It then made its way back to an American port where more extensive repairs were affected.
The Gunnel story was typical of those Fleet Type submarines equipped with H.0 .R. engines. Although Commanding Officers complained bitterly of their poor performance, the last engines remained in service until 1944.
America was not alone in experiencing diesel engine teething problems. In Great Britain the Admiralty grew increasingly concerned by 1913 over serious delays in Vickers releasing its new diesel for the Royal Navy’s more modern E Class boats. It sent Engr.Lt. William F. Rabbage to work for Vickers to help solve the engine delivery problem.
There he found that the smoke/power troubles were mainly in the injector nozzle design for its new common rail fuel system. His trial and error solution was then used in all of the Vickers diesels. The ensuing 12 cylinder, 100 hp/cylinder engines would become the backbone of the British submarine fleet. That same year, Vickers lost its contract with the Admiralty as the sole supplier of submarines to the Royal Navy. Until then, it had controlled both the hull and engine designs. Ongoing disputes grew between Vickers and the Admiralty over differing design philosophies. One involved the hull’s engine bed rigidity. Vickers had designed the engine and its hull mounting as a unit, but the Admiralty’s L Class boat engine bed stiffness was greatly reduced without consideration of the Vickers engine demand for greater longitudinal strength. Rabbage later referred to the 12 cylinder engines in these L boats as the Vickers’ Underslungs, meaning that they were hung by their exhaust manifolds.
One outcome of these quarrels was the transfer of all submarine engine developments to the Admiralty Engineering Laboratory (A.E.L.). This resulted in a long series of designs having inherent structural and dynamic weaknesses. The A.E.L. also abandoned the common rail fuel system where fuel was hydrauli- cally injected. It instead reverted to the earlier air injection method where high pressure air blasted vaporized fuel into cylinders. While this system reduced exhaust smoke, the Admiralty complained that the Vickers engine would require a problem- prone, multi-stage air compressor. Meanwhile, those not so constrained were working on hydraulic injection systems to eliminate the troublesome compressor. Vickers continued using the improved common rail system on engines being sold to foreign navies.
The Vickers-A.E.L. conflict continued up to the doorsteps of the Second World War. By that time the Admiralty had designed and was building its T Class ocean going submarines still without a reliable A.E.L. diesel which was still undergoing tests at its Chatham Naval Dockyard. Vickers, also building T boats, was by necessity authorized to install its proven engine with a common rail system based on experience gained on those used by the numerous foreign navies. Even so, the Admiralty continued proposing other designs. Shortly before war broke out, it bought Sulzer and M.A.N. licenses and assigned British companies to make the engines. The M.A.N. engines, built by Scott Shipbuilding were failures in the three T boats receiving them. The Sulzer engines likewise suffered from builder inexperience and A.E.L. design changes, although they did gain a credible service performance by war’s end.
The Royal Navy faced a spare parts problem during much of the war because of a plethora of engine types. With four different designs in the T boats alone, plus the engines for older as well as smaller submarines, spares for 14 makes and models were needed. 9 At war’s end, the Type XXI German submarines captured by America were so remarkably superior to the Fleet Type submarine, the Navy immediately set about to build an attack class boat that would incorporate many of the Gennan innovations. Once again, the designers sought a light-weight, high-output diesel engine. The Tang class submarine was to be considerably shorter than the Fleet Type boats and the single engine room had to accommodate both engines and generators. While the Guppies of the time had 53 feet of hull length devoted to main propulsion, the Tang class boat was to have almost the same total horsepower output in 22 feet of hull length. To accomplish this, the Navy centered its attention on a radial diesel engine. The GM 16-338 (surface ship model number l 6-l 84A) had four decks of four horizontally arranged cylinders. These 16 cylinders turned a vertical crankshaft that drove a generator below the engine. Four of these enfcines with generators were crammed into the 22 foot compartment.
Engineers of Cleveland Diesel Engine Corporation, a division of General Motors hadn’t sufficient time to test the new type of engine in a submarine. Navy not foot submarine- chasers used these vertical crankshaft engines which were geared with right angle drives to the propeller shafts. These proved to be passably reliable, but the demands of a submarine were much more severe. The Navy had a shipyard schedule to keep and the result was the installation of an engine of unproven quality.
Diesel engines run at specified speeds. The opposed-piston, twin-crankshaft Fairbanks-Morse ran at 720 rpm and the General Motors at 750 rpm. The GM 16-338, Pancake engine ran at 1600 rpm, approximately twice the speed of the earlier Fairbanks-Morse 1,600 hp, 380 8 1/8 engine and General Motors 1,600 hp 16-278A engine. Engine room noise was likewise excruciatingly in- creased.
USS TANG (SS-563) and USS WAHOO (SS-565) were the first boats completed. WAHOO’s engines experienced some difficulties on the way from mainland USA to Pearl Harbor. T ANG’s engines were so severely damaged during the trip its WesPac tour had to be canceled and the boat went into the shipyard for repairs. The Tang class boats were to suffer from the age-old desire to get more power from less weight. In the cramped space, enginemen and electricians, struggled to keep some of the engines going. Soon torpedo men and auxiliary men were pitching in. It was a twenty-four hour, non-stop effort. The engines vibrated from their light weight and rubber sound mountings, causing parts to fail. Lines ruptured and gaskets leaked. Oil and cooling water dripped down into the generators causing grounds and shorts.
The GM 16-338 engine was also used in USS ALBACORE (SS-569). One of its executive officers, Lou Urbanczyk, listed the engine’s weaknesses, ” . . . weak retainers for piston rods … the spherical thrust bearing at the bottom of the engine wiped … the expansion joint for the exhaust kept breaking, not flexible enough . . . etc.
Commander David A. Kratch, commanding ALBACORE, later wrote, “Their unreliable operation is well documented in the annals of naval history. . .The number of overhauls have precipitated the following operating restriction; if one engine fails, immediately return to port.'” 3 ComSubLant, Admiral E. W. Grenfell noted that the unreliability of the pancake diesels required that a surface vessel accompany the ALBACORE or that the boat could not operate beyond sight of land.
The Navy gave up on the GM 16-338 pancake engine. It extended the Tang Class hull length to accommodate well-proven Fairbanks-Morse engines. With the advent of nuclear propulsion the problems involving submarine diesel engine design faded into obscurity.