OS type 6 (K6)
No. 42 in a series compiled by David R. Janson,
SAM #273, AMA #78416 and MECA #210-04.



When the "reproduction" phase of duplicating favorite model airplane engines peaked in the late 1980's, having been spurred on by modelers world wide who wished a spark ignition engine for their old timer models, it was just a matter of time before one of the "majors" put out their own replica. Thus Ogawa Seisakucho (O.S.) of Japan chose to replicate their 1940 O.S. Type 6 (K6) of .56 cid. Historically, in 1936 Mr Shigeo Ogawa of Osaka, Japan built his first gas model engine and with just one employee formed the Ogawa Model Mfg. Co. Ltd. Mr. Ogawa died a few years ago but his company today in 1999 continues to be the oldest surviving, in continuous production and the largest in the world. To commemorate the 50th anniversary of O.S. a very limited production of 2,000 of the K6 was produced.

Beautifully packed for the modeler, the K6 came mounted on a green wooden stand, with spark plug, ignition coil, condenser, wiring and a copy of the original booklet that accompanied the 1940 engine. All was contained in a light brown corregated box clearly stamped OS K6 Ignition Engine in the same lettering as the original. But, of course the best part was the superb quality of the replica K6 engine.

This single-cylinder, two-stroke, side exhaust with crossflow scavenging just sparkled. The all aluminum sand cast engine had upper and lower parts fastened together with two large bolts. Cast in beam mounts and a screw in back plate were features of the lower part, while the one piece upper case included the cylinder head, both case and head with machined fins. A screwed on bypass and exhaust on the right side and a centered Japanese CM-6 spark plug were featured. The cast and machined intake was part of the gas tank top screwed into trecase.

An all brass needle unit, centered on the intake and tank had a gits cap next to it. The round tank ring held the plastic tank securely. Internally the cast, ringless with baffle aluminum piston was worked by a cast, bushed rod, working the steel crankshaft set in a brass bushing. The open "Bunch type" timer, the drive washer/cam, aluminum prop washer and steel nut complete the engine. The bent timer arm has an attractive, small plastic tip in place. All work, machining, castings, etc. were of the highest order with the engine being all "silver" aluminum in color. "OS" is on the front of the case casting, the bypass cover, one lug and the serial number stamped on the other lug. Full "modern" running instruction, safety warnings, wiring diagram and all sorts of hints are part of the paper package. Flawlessly manufactured by O.S. and never to be done again. Initially offered at $250 a flurry of discount activity dropped to the $160-$190 range in Feb. 1988. Engines were scooped up by collectors and today some 10 years later it is seldom that one comes into the market and if it does the price has doubled.

No other manufacturer has replicated an engine from their early production years. This beautiful engine is one of todays collecting gems and a certain future rarity. I wonder if anyone has actually flown these engines in their old timer airplanes!!


This page reprinted from "Model Engine Designer and Manufacturing Profiles" by permission of the author, Mr David R. Janson.



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