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HOR's and other engines Part One

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    Posted: 20 Dec 2018 at 3:40pm
I don't have many of these things written but will continue to post them from time to time.

HOR's and Other Engines --- Part One 

The period from 1932 to 1942 saw a profound change in the US submarine force. Not without problems. Not the least of the problems was what engines were the best for the new 'diesel electric' drive.

This article is an explanation of one part of the teething problems in selecting the 'proper' engine. For those of you who have or have access to Freidman's “US Submarines Through 1945” and Alden's “The Fleet Submarine in the U.S. Navy” this article will cover ground already well described in those two books. In addition there is more information from C.C. Wright's essay published in Warship International.

In the late 1920's the US Navy was looking at the growth of the submarine forces in England, France and Japan. The US had a large force but not of modern submarines. New design concepts included a two fold increase in the size of submarines which forced new thinking about propulsion systems. If the submarine grew by a factor of two the required shaft horsepower necessary to maintain the same speed of the smaller submarine would necessarily grow by a factor of eight. Larger diesel engines were not a solution because the engines still had to fit inside the hull which didn't grow much in diameter so the number of engines would have to be increased. That involved complex direct drive shafting problems such as those tried in the early 'fleet submarine' and 'cruiser submarine' designs that followed the 'S-Class'.

The Bureau of Engineering requested proposals for diesel engines for submarines. This was done at a time when the diesel generator was coming on line as a motive power in the railroad industry and was seen to be a viable replacement for the steam engine. With the advent of this diesel electric drive the submarine force could get away from the direct drive diesel propulsion. Coupled with diesel electric drive was the need for a more sophisticated centrally located control system for the routing of electrical power from the diesel generators to the motors, controlling propulsion motor speed and controlling battery usage including charging.

Initially Winton diesels were seen to be the best option of the five companies to respond to the request for proposals. Winton diesels were the first to include high pressure fuel injection mounted on each cylinder. This simplified the piping system for the engine making them more reliable. Their engines were used by the Electro-Motive Company who was involved in creating electric propulsion for trains replacing steam engines. In 1930 General Motors Corporation purchased both the Winton diesel and Electro-Motive companies melding them into the Winton Diesel Company. Eventually the company took the name of the city in which they were located and became the Cleveland Diesel Company.

Two additional diesel manufacturers entered the picture also and asked to be considered. These were the Fairbanks Morse Corporation and Hooven-Owens-Rentschler.

The three diesel engine types selected to be used by the submarine force were the “V-block” General Motors, the “opposed piston” Fairbanks Morse and the 'double acting” Hooven-Owens-Rentschler (HOR) engines. The website of the Historic Naval Ships Association has the submarine diesel instruction manual at “” which contains good explanations of the types of diesels.

The FM engines (FM 1200 HP 38D) were slated to go into new construction boats (Plunger and Pollack) at the Navy Yard in Portsmouth, NH. The GM engines (Winton 201) to (Shark, Tarpon, Perch) at Electric Boat and the HOR engines were to go to Pompano at Mare Island. As these submarines came on line and were tested problems came to the fore.

The GM engines smoked excessively which was important because it gave away the submarine's position while on the surface. To correct this issue the pistons were changed from aluminum to iron and the lubricating oil system was changed to increased capacity. These changes would be expensive. The 201A's gave disappointing performance on the long patrols being seen in the Pacific. The 60 day patrols involved longer underway periods than had be contemplated during peacetime. This meant the engines were seeing many more hours use between alongside maintenance.

The FM engines were generally not tested enough to reach a conclusion as to their reliability and it was felt that they might not be as robust as necessary. Cracks in the water jacket and burned pistons of the FM engines required expensive repair parts stockpiles.

Of all the engines, the ones made by Hooven-Owens-Rentschler (HOR) gave the most problems. A letter from ComSubPac to the Chief of Bureau of Ships listed the actual problems. These included: Inaccessibility of components was so bad that inspections of pistons, oil and fresh water coolers could not be properly performed. Vibration was such that component piping cracked after 'a few hundred hours of operation'. Piping runs were poorly designed and made work on the engines difficult. Lubricating oil consumption was excessive. The engines required more air than Winton or FM engines. This meant the engine rooms were wet due to the high airflow rate in the inductions entraining an excessive amount of salt spray. Cylinder blocks, being flame hardened were prone to excessive wear. Fuel consumption was higher than Winton or FM engines. The bottom line was that the engines were unreliable which in a wartime situation was intolerable. To correct the problems would take a complete redesign of the engine then changes to the engines already in production for submarines, patrol craft and some destroyer escorts.

End of part one.  Stay tuned for the next installment.  Maybe next week.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote gerry Quote  Post ReplyReply Direct Link To This Post Posted: 20 Dec 2018 at 6:12pm
Thank you for taking the time to write and post these. I find them an enjoyable read and I'm sure others do too!
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