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Saras Associates Precision Manufacturing
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Cox Sure Start Engine w/Throttle



RC Throttle for Cox .049 Glow Engines

Historically, the use of Cox Glow Engines to power a radio control (RC) airplane followed this concept: “Start the engine at full RPM, hand launch the plane and fly until the tank emptied, then glide the plane to a safe landing”. This was the scenario since an effective throttle did not exist.

Although numerous attempts were made to devise some type of speed control, they generally involved restricting the exhaust. Exhaust restrictors provided a degree of speed control, but the top end performance of the engine was significantly reduced and the engine could not be completely shut off. In addition, the exhaust restrictor throttle sleeve eliminated the ability to use a muffler.

Recently, we developed and manufactured an effective throttle for the Cox .049 glow engine that enables the user to run the engine at variable RPM levels as well as to idle and completely shut down the engine. It also allows the use of a muffler.

This development opened up throttling ability previously found only in larger engines developed for RC use. It is hooked up to a throttle servo and effectively controls engine speed, similar to any RC engine throttle.

The concept will work equally well on most post 1956 Cox .049 reed valve engines usedto power RC airplanes, boats or cars. The model airplane enthusiast can now start the engine, run it at various RPM levels (controlled via the RC transmitter), then idle the engine to enable the airplane to taxi onto the runway, take off, land and perform “touch and goes”.  By throttling back on the engine speed, fuel economy is greatly increased.

The throttle is simple and inexpensive and can be retrofitted to most Cox .049reed valve engines. It is sold either by itself with intake tube (for Surestart engines) or with a backplate package (to convert engines with integrated tanks). Also available are different glow head conversions for modelers wishing either higher performance or lower RPM than with the stock glow head; as well as engines with the throttle already integrated.

To learn more about this ingenious device or to purchase the throttle in any one of its many configurations, please visit the following website;



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                                        P.O. BOX 547 - ROCKLIN, CA - 95677  PHONE (916) 933-0050  FAX (916) 933-0070 EMAIL: INFO@SARASINC.COM