heli_headcase
Key Veteran
Location: Hovering around Atlanta
My Posts This: Topic Forum | Fly it and Try it...Unless there's going to be a big engineering change in the frame or engine mount design, why not allow some room to try a number of different ratios?
The lower (numerical) ratio of the 88 & 18 (4.89-1) will put less stress on the rotating parts of the engine but put higher demands on the cooling system. The reverse is true for the 83 & 15 (5.53-1) ratio but at 1800rpm you're spinning the engine at very close to 10Krpm.
The specs on Horizon's site don't state the exact peak torque or peak HP rpm, only the max rpm limit of useful power (10,000). That upper limit is okay for an occasional overspeed but I'd stay away and consider picking a running rpm of more like 9,000.
I know the gear center-to-center distance will vary considerably if wide ratio changes are picked but I'd allow for the 88T main and 16-18T clutch pinion to start. Blade length and max pitch will be the final determining factor and you may discover the 1800 head speed could be too high.
You're close, fly it and see what happens. Just don't over speed or over temp the engine before you're done.
Hope this helps...
HHC
So many heli's - too little time... |
