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: 09.01.08

[Back to Home Page] Suggestions? Corrections? Remarks? e-mail: Martin Hepperle.

Due to the increasing amount of SPAM mail, I have to change this e-Mail address regularly. You will always find the latest version in the footer of all my pages.

It might take some time until you receive an answer and in some cases you may even receive no answer at all. I apologize for this, but my spare time is limited. If you have not lost patience, you might want to send me a copy of your e-mail after a month or so.
This is a privately owned, non-profit page of purely educational purpose. Any statements may be incorrect and unsuitable for practical usage. I cannot take any responsibility for actions you perform based on data, assumptions, calculations etc. taken from this web page.

© 1996-2008 Martin Hepperle
You may use the data given in this document for your personal use. If you use this document for a publication, you have to cite the source. A publication of a recompilation of the given material is not allowed, if the resulting product is sold for more than the production costs.

This document may accidentally refer to trade names and trademarks, which are owned by national or international companies, but which are unknown by me. Their rights are fully recognized and these companies are kindly asked to inform me if they do not wish their names to be used at all or to be used in a different way.

This document is part of a frame set and can be found by navigating from the entry point at the Web site

Impressum und weitere rechtliche Hinweise für Deutschland