ch-47c
Senior Heliman
Location: san jose, ca
| Shiro,
YS 91SR Red Head Long Stroke with Hatori SB19 muffler. I don't know if that muffler designation is available in Japan. I'm sure there is an equivalent model. YS recommends a ratio of 1 to 7.5/8.0 to prevent overspeeding of the engine.
The kit comes with a 15 tooth pinion gear and 124 tooth main gear. There is supposed to be an optional 14 tooth and 16 tooth pinion gear. There is also an optional 126 tooth main gear and 130 tooth main gear. I can't find any of the optional gearing, though the 16 tooth pinion has supposedly been available in the last week. Some guys are making their own gears.
I emailed T.B. about the gear ratio using the standard parts, which equals 8.266, and he said with the YS 91SR it is fine just keep the rotor rpm under 1850. This ratio gives you an engine rpm of appx. 15,292 rpm. YS manual says the practical rpm is 2000-17,000 rpm.
This heli also flys fine with .61/10cc engines, though not like a ballistic missle.
Rich |
