Schroeder 09 (oz13745)

About this Plan

Schroeder 09. Model aero engine.

For more detail on the Schroeder 09 see: http://modelenginenews.org/schroeder09/index.html

Quote: "The Schroeder 09 was the first 'full' engine design to appear by (wait for it), Roger J Schroeder. It appeared in The Engine Collectors' Journal at the beginning of 1974 and was Roger's second construction series for ECJ. Prior to this, he had described a little horizontally opposed twin based on Cox 020 cylinders and it was the positive response to this engine which decided him that an audience existed ready and eager for the Words and Music (as LBSC might say) for simple IC engines for home construction.

The first part of the new series had been preceeded by a lead-up over several issues in Roger's regular 'Engin-uity' column where he discussed aspects of design he thought were important in an engine that could be built from scratch by anyone of modest mechanical ability, with limited shop facilities. Bravely, he built the prototype virtually in step with the publication dates and it must have been a relief to him that the finished product ran to expectations without any changes to previously published plan parts.

Design-wise, the '09 contains a few things that Roger later changed his mind about, but that is part of the learning, evaluating, and revising cycle. Let's look at the basics first.

The engine is fully machined from bar-stock and apart from the points, no commercial items are used. It is a square (equal bore and stroke) bulkhead mounted two-stroke with a front rotary valve induction (FRV) and fluted Cox-style transfer passages that can be built for either spark or compression ignition. In the latter case, the timer assembly is omitted and a taller cylinder and contra-piston added. The bulkhead mount doubles as a fuel tank.

Now for the less usual features. The crankshaft is supported in twin ball-races. This requires high precision from the builder and Roger states a tolerance of plus/minus 0.0 in this regard. Fine if you've some sound machining experience, but a bit of a challenge otherwise. The piston is a thin cast iron shell, recessed near the bottom for a steel circlip that retains a wrist-pin carrier..."

Direct submission to Outerzone.

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