Mercedes-Benz 500 Series Diesel Marine Engines

A follow up to the Daimler-Benz DB 602 (LOF-2) engine

By William Pearce

Daimler-Benz was formed in 1926 with the merger of Daimler Motoren Gesellschaft and Benz & Cie. Prior to their merger, both companies produced aircraft engines under the respective names Mercedes and Benz. After the merger, the Daimler-Benz name was used mostly for aircraft engines, and the Mercedes-Benz name was used mostly for automobile production. However, both names were regularly applied to marine engines. For clarity in this article, the name Daimler-Benz will refer to aircraft engines, and the name Mercedes-Benz will refer to marine engines.mercedes-benz-mb-500-v-12

As Germany began its rearmament campaign in the 1930s, high-performance marine diesel engines were needed to power various motorboats. The Kriegsmarine (German Navy) turned to Mercedes-Benz to supply a series of high-speed diesel engines. These engines were part of the MB 500 series of engines that were based on the Daimler-Benz DB 602 (LOF-2) engine developed to power the LZ 129 Hindenburg and LZ 130 Graf Zeppelin II airships. The 500 series diesel engines were four-stroke, water-cooled, and utilized a “V” cylinder arrangement.

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Daimler-Benz DB 602 (LOF-6) V-16 Diesel Airship Engine

By William Pearce

Around 1930, Daimler-Benz* developed the F-2 engine, initially intended for aviation use. The F-2 was a 60 degree, supercharged, V-12 engine with individual cylinders and overhead camshafts. The engine had a 6.50 in (165 mm) bore and an 8.27 in (210 mm) stroke. The F-2’s total displacement was 3,288 cu in (53.88 L), and it had a compression ratio of 6.0 to 1. The engine produced 800 hp (597 kW) at 1,500 rpm and 1,000 hp (746 kW) at 1,700 rpm. The engine was available with either direct drive or a .51 gear reduction, and weighed around 1,725 lb (782 kg). It is unlikely that the Daimler-Benz F-2 powered any aircraft, but it was used in a few speed boats.

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The First Ruger


In doing some research for the “From the Editor” for the September issue, I spent some time looking at William Batterman Ruger’s first contribution to American Rifleman, and no it wasn’t his “.22 Ruger Pistol” that made its debut in a September 1949 advertisement, nor was it Technical Editor Julian S. Hatcher’s extremely favorable review of “two production-line samples of the .22 Ruger” that ran in November 1949.

No, the first Ruger in the magazine was an article written by the young inventor in December 1943, at a time when he was working on a machine gun design for the U.S. Ordnance Dept. Titled “Semi-Automatic .250-3000,” Ruger detailed the conversion of a Savage Model 99 from a lever-action to a gas-operated semi-automatic, noting “This conversion can be accomplished with only superficial changes in a few of the parts.” Even in this first gun, aesthetics mattered to the young inventor: “The rotary type magazine has adequate capacity and does not require projections on the exterior of the gun.” Of course, some of those features would be seen in Ruger’s later designs, especially a flush-fitting rotary magazine.

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The Smith & Wesson Model 25-5

Even though I prefer the 4″ N Frames, my 6″ 25-5 is a joy to spend range time with…

Gunner's Journal

The S&W model 25-5 is one of those revolvers that has gained classic status along with most of the other “N” frame S&W’s made before the lawyer proofing started with those darn framelocks that everyone loves to hate myself included.
A couple of years ago you could buy about any older S&W revolver for very little money but these days people have come to realize that these wonderful revolvers are something special and prices have increased accordingly. Most any S&W “K” frame will sell in the $450 to $500 range with “N” frames at $600 plus depending on how rare they are. I recently saw a nickel 6 inch 41 magnum marked at just under $1000! A word to the wise if you have one keep it!
My journey with the S&W “N” frame started in 1976. At that time the model 29 was the revolver to buy. Barrel length…

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Savoia-Marchetti S.65 Schneider Racer




The unorthodox Savoia-Marchetti S.65 was intended to win the 1929 Schneider Trophy Race for Italy. Unfortunately, the aircraft crashed and took the life of Tommaso Dal Molin.

By William Pearce

After the Italian team was defeated on its home turf at Venice, Italy in the 1927 Schneider Trophy Race, the Italian Ministero dell’Aeronautica (Air Ministry) sought to ensure victory for the 1929 race. The Ministero dell’Aeronautica instituted programs to enhance aircraft, engines, and pilot training leading up to the 1929 Schneider race. Early in 1929, the Ministero dell’Aeronautica requested racing aircraft designs from major manufacturers and encouraged unorthodox configurations.

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