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Synergy 766 Gas

This is my new project for 2018 - a Synergy 766 with a gas conversion by Carey Shurley of Gas Powered Helicopters. It will be using a Zenoah Toxic VX310 stroker. This engine is a RC format built by TRM Power from the G290RC engine with a 2mm stroker crank, lightened piston and balanced rotating and recip assemblies.

This is what the model looks like in completed form. This one is not mine - I just have it in my shop installing an autopilot it for UAV use:

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The donor kit is mostly used, except for frame sides and battery tray and a few small items. The gas conversion kit has all the parts (minus the engine, clutch, generator, and muffler) to complete the build.

It starts with a different baseplate for the frame that fits the TRM RC format engine:

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All the parts for the head and frame are put together and the frame sides married

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The clutch bell and top start system is included with the kit. Top start coupler is a standard 6mm hex drive. This is the clutch bell and a closeup of the installed assembly. The pinion shaft bearing blocks are adjustable in the frames for main transmission gear backlash adjustment. The clutch bearing blocks have set screws in the holes that push against the pinion shaft bearing blocks to adjust the tension of the belt primary drive.

The belt primary is a .917 ratio. The final drive is a 8.18:1. Total gear ratio is 7.49:1. 10,000 engine rpm gives 1,335 rpm headspeed. Since this model will have 806 blades, the main rotor diameter is exactly 6 feet. The tail transmission has three ratios available, I will be using the standard 4.7 transmission input gear, or 6,275 rpm tail rotor speed with 116 blades. Tail rotor diameter is 12".

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I'll have some more on the build as I progress with it.