Some Performance Data

Recently people have been asking for performance figures of Cox engines. This is because these engines have been used in various small unmanned aerial vehicles (UAVs) for academic and commercial applications. The power to mass ratio of these small engines  still makes them a very attractive choice for these applications.

The curves below have been created by digitizing graphs from old model magazines. I have never built a dynamometer small enough for these engines. The power output has been converted to SI (metric) units.
Special thanks go to Bob Gardner, Peter Tarn and Peter Grünbaum for digging out the corresponding magazines.

The smallest Engines (.010 ... .020)

The power output of the small Tee Dee .020 is really not bad when compared to the larger and heavier engines. The tiny Tee Dee .010 produces excellent results at high speeds above 25'000 1/min.

The small Engines (.049)

The power output of all .049 reed valve engines seems to be limited to speeds between 12'000 and 17'000 1/min. This is probably due to blockage effects caused by the narrow flow paths around the reed valve. The Tee-Dee .049 shows its clear performance boost over the Medallion, albeit at higher speeds only.

The medium sized Engines (.09)

We note the clear power advantage of the Tee Dee over the Medallion, but take into account that the nitro content of the fuel was different.

The large Engines (.15)


The .15 Special Mark II shows the best performance figures for the traditional Cox .15 engines. This is probably due to the new porting system and different timing. Only the Conquest .15 with its radical new design could be run at even higher speeds to outperform the Special.

Last modification of this page: 21.05.18

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