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Tricks for the Thunder Tiger GP-07

The Thunder Tiger GP-07 is a .069 cubic inch engine for radio-controlled airplanes. It outputs .20 horsepower with a practical range of 3,500 to 24,000 RPM. An air-bleed single needle carburetor features simple needle valve adjustment, and the GP-07 comes standard with a three-chamber expansion-style muffler. In most application, this engine runs on a fuel blend consisting of 25 percent lubricant and 75 percent methanol. A 5 percent to 15 percent nitromethane with 20 percent lubricant blend may be substituted for increased power.

Installation
- Mount the engine only to rails made of rigid hardwood such as maple or to a metal or nylon radial engine mount. Performance of the GP-07 is directly impacted by the location of the fuel tank and the length of the fuel line. Mount the tank as close as possible to the engine with the center line of the fuel tank level with the engine needle valve.
Propeller
- Use a 6-by-3 propeller during the engine break-in period. Following break-in, a 6-by-3, 6-by-4 or 7-by-3 propeller is suggested. Check the balance of any new propeller before use to prevent possible damage. Use a commercially available prop balancer to verify the balance of any propeller before installing it on the engine.
Break-In
- Ideally, at least one full tank of fuel should be run through the engine on the ground -- either mounted on a test stand or installed in the plane -- before the engine is flown. The remainder of the GP-07 break-in can be performed as the plane is in the air.
Needle Valve Optimization
- Start the engine and open the throttle all the way. Rotate the needle valve clockwise until the RPM begins to increase. Disconnect the glow plug. If the engine stops, rotate the needle valve another 1/8 turn clockwise and re-start the engine. Continue turning the needle valve 1/8 turn clockwise, listening for the RPM increase. When there is no further immediate RPM increase, rotate the needle valve counterclockwise back to the peak RPM position then clockwise again very slightly to richen the mixture a small amount. Always adjust for a richer mixture on the ground to compensate for the engine's tendency to lean out once in the air.

Aviation