Updated: 13-Nov-2018
Founded in Syracusa, by H.H. Franklin and John Wilkinson in 1901 for the manufacturing of automobiles.
“Franklin logos”
-It was known in 1935 as an automobile manufacturer and as Aircooled Motors Co. when it started manufacturing aviation engines.
-Franklin made in general, air-cooled, horizontally-opposed cylinder engines, with an offer from 60 hp with two cylinders, 90-150 hp with four cylinders, or 150 to 270 hp with six.
-In 1971, for example, they only built 5 models between 60 and 250 hp: 2A-120, 4A-235, 6A-335, 6A-350 and 6AS-350.
-There have been multiple vertical versions for helicopters.
-There were also three models built in Poland (PZL), the two, four and six cylinder engines.
-The 8-cylinder was made with two displacements, the 8C-398 and the 8C-538. Years 1941-42.
-Experimentally they made an exceptional horizontally-opposed 12-cylinder engine, which was barely known. It was the Franklin 12AC-596 and 12AC-806. Year 1941
“12AC-596”
-The US Military denomination for the 12AC-596 was O-595.
-There was a larger variant, the O-805, or 12 AC-806, with the same configuration as the -596. Year 1942.
“O-805”
-The 60 hp, 2-cylinder models were the 2A4 from 1945, and the 2A-120 from 1971 (O-110 and O-120, respectively).
-They were especially for home-made aircraft builders and motor-gliders.
“2A-120”
-The 4A had several versions, the 4AC-100 with military denomination O-200-1 and with reduction gear O-200-5.
-The 4A were made as 4AC-199 giving 90 hp at 2,500 rpm. The 4A4-100 was installed on the Monocoupe 90.
“4AC-199”
-The 4AC-150 (this was the first Franklin engine built in 1938), the 4AC-171, the -175 and -176 were mounted on the Aeronca 60 model with 65 hp all of them.
“4AC-176”
-Recently we received two new photographs of Franklin engines from the early days of the brand.
-One of them is the 4AC-150, which we see with cooling deflectors placed on top of the cylinders.
“Franklin 4AC-150”
-The other is the 4AC-171, also with four cylinders and with upper deflectors installed.
“Franklin 4AC-171”
-The former delivered 40 hp and the latter 60 hp.
Franklin was a brand of Aircooled Motors Co., and was established around 1938 in Syracusa, in the state of New York.
“4A-235B”
-The 4ACG-199 that gave 113 hp was installed on the small Interstate L-6 "Grasshopper". This version had reduction gear. The ungeared version was the 4AC-199. The 4A-235B delivered 130 hp at 2,800 rpm, and is from 1964.
-The 6A 6-cylinder series were 6A3, 6A4- 150, -165, -200. The 6AL-315. The 6A8-215 gave 215 hp at 2,800 rpm. The 6AC-198, -298 and -405. All of them were built between 1940 and 1945.
“6AC-298”
-The 6A-335 with 6.23 liters of displacement delivered 180 hp at 2,300 rpm. (1945).
-The 6A-350 with 9.56 L of displacement gave 220 hp at 2,800 rpm and the supercharged version 6AS-350 delivered 250 hp up to 4,500 meters of altitude approx. and a continuous maximum power of 235 hp up to 5,000 meters.
-The vertical versions to be installed in helicopters were mainly the 6V-335, 6VS-335, and 6V4-178. All of them were mounted on the Bell B-47. The 6V-350 shared mounting with Bells and Hillers.
“6V-335”
“6VS-335”
-The 6AVC-405 and -425 can be included in this group.
-After WWII, Franklin can be considered the third most important brand for general aviation in piston engines, after Continental and Lycoming (or Lycoming and Continental).
-More information on the XO-540 from 1943 to 1947 can be found in the USNA 3843/452.8 file, and on the XO-200 of 1941-48 in the 3897/452.8 file.
From Appendix 6: Franklin Aircooled Motors was the third largest general aviation brand together with Lycoming and Continental.
-New photo of a 4AC-150, of the first period.
“El Franklin 4A-235”
From Appendix 9: A six-cylinder Franklin engine version has been located in an Italian museum. This engine has been designed to be installed as a pusher.
“Extension for the propeller”
-Possibly for an Italian amphibian (Piaggio). With the engine in the thick part of the wing and the extension to emerge from the trailing edge. The shape of the blades confirm this installation.
From Appendix 12: Color photo of the horizontally-opposed, 12-cylinder engine (12AC-xxx).
“Franklin 12AC-xxx” (PiP)
“Horizontally-opposed 12-cylinder engine”
Engines of FRANKLIN
Model: 12AC-596
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"Franklin 12AC-596, fig. 2"
Model: 12AC-806
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Model: 225
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Model: 2A-120 (O-120)
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"Franklin 2A-120"
Model: 2A4 (O-110)
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Model: 425
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Model: 4A-235
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"Franklin 4A-235B"
Model: 4A4-100
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Model: 4AC-100, -150, -171, -175, -176 -199
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"Franklin 4AC-171"
Model: 4ACG-199
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Model: 6 cils TurboSupercharger
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Model: 6A-335, -350
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Model: 6A3
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Model: 6A4-150, -165, -178, -200
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Model: 6AC-298
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"Franklin 6AC-298"
Model: 6ACV-405
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Model: 6AG-199
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Model: 6AL-315
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Model: 6AS-350
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Model: 6AV-335
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Model: 6AVC-405, -425
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Model: 6V-335, -350
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"Franklin 6V-335"
Model: 6VS-335
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"Franklin 6VS-335"
Model: 8C-398
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Model: 8C-538
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Model: AC-198, -298, -405
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Model: O-110
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Model: O-120
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Model: O-200-1, -5
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Model: O-335
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Model: O-540
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Model: O-595
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Model: O-805
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"Franklin O-805"
Model: XO-200
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Model: XO-540
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