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The Douglas DC-3 (civilian) C-47 (military) aircraft may be the closest thing to an indestructible, ubiquitous, immortal aircraft ever built.

The engines are Curtiss-Wright R-1820 cyclones: R for radial, 1820 for its cubic inch displacement. It is a single-row, nine cylinder engine.

The distinctive sound is because it is air-cooled, and hence not muffled by glycol liquid cylinder sleeves, and because it has fewer cylinders than a typical liquid-cooled engine (V-12): loud and rough.

The Cyclone was primarily a cargo/bomber engine. The B-17 used turbo-supercharged versions of this engine rated at 1,200 HP at altitude, enabling high-altitude precision daylight bombing (via the top-secret Norden bombsight).

Some fighters used it, mostly export versions of planes like the Curtiss P-36 (Mohawk) and Grumman F4F (Martlet, Wildcat). The main US fighter to use it was the Goodyear FM-2 (license-built Grumman F4F) with a turbo-supercharged Cyclone.

The first Navy monoplane fighter, the Brewster F2A (Buffalo), used it exclusively. The Buffalo was much maligned in America, but was actually an advanced design, aerodynamically superior to the Wildcat, much more maneuverable, and with a better climb rate in its first and second versions.

The Wildcat was a better carrier landing aircraft, an important factor, but its main advantage over the Brewster was that the Pratt & Whitney R-1830 Twin Wasp used in many (not all) of the US Wildcats had a 2-Stage mechanical supercharger versus a 1-Stage in the Cyclone. This gave it more speed at 20,000 feet, where the Mitsubishi A6M Zero-Sen, which also had a 2-Stage, was often encountered.

A side-by-side comparison of the Brewster and Wildcat powered by the same version of the same engine, the 1-Stage R-1820-40, showed the Buffalo to be about 14 MPH faster.

Supercharging was a critical factor in aircraft performance, often overlooked. The P-51 Mustang would never have succeeded as well as it did without the Rolls Royce Merlin with its spectacular 2-Stage mechanical supercharger.

Had a 2-Stage unit been developed for the Cyclone engine early enough, the F2A would probably have had a much different history with the US. (Turbos were not generally available for fighters in early WWII, so mechanical superchargers were used, except for large, heavy fighters like the P-38 and P-47.)

One Navy pilot who flew every major US fighter type in WWII against the Japanese fighters asserted that the F2A-2 (second version) was the only one that could have engaged well in a dogfight with the Zero; by the time the Navy encountered them in combat, the Dash-2 had been withdrawn from front line service, in favor of the Dash-3, which was inferior in performance and maneuverability.

The modified F2A-1s flown by the Finnish air force achieved a kill-to-loss ratio of close to 26-to-1 - up there with the Flying Tigers - while flying the Buffalo. They nick-named it the Sky Pearl. Finnish aces shot down many Russian and Allied (Lend-Lease) aircraft, including MiGGs, Lavochkins, Spitfires, Airacobras, and others.

The Cyclone functioned better in the colder, denser air of the north, and the Finnish pilots were very well trained. The Buffalo with its Cyclone engine, the front line fighter until 1944, massively outnumbered by the Russian air force, literally helped save Finland from Russia in the Continuation War.

Eino Luukanen, Finnish ace, wrote about his experiences flying the Brewster Buffalo in Fighter over Finland.