Use your gearbox to multiply your torque is the deal. Not just for automotive engines either. It flat works, and works well.
Just as Waterthunder has been saying for a long long time. It really is as simple as that when done right. You'll find yourself swinging more prop, not necessarily more RPMs. The same benefits will come that an automotive airboater gets with a deeper reduction also. Less fuel burned, better max push, super cruise economy, less sound, and probably less overall wear and tear on your engine.
They have an adapter out for a rotator to gpu cases, but I'm not sure how far along they are with the Continental and Lycoming A/C engine adaptors. Those are in the works, but I don't know how long it will be.
There seems to be plenty of auto engine airboaters out there who are deciding to go to an even deeper reduction in order to swing bigger props slower. It works, and they are gonna be glad they did. Heck, with gas prices as they are, the upgrades may pay for themselves in short order depending on how much running they do.
Of course there are some newer slow turning props out now that are designed to work well at the reduced propeller rpm's, and that's helping to spur interest in the deeper ratios.
Same as many auto guy's, aircraft engine airboaters are scared that they will be screaming way to many RPM's. If you get it geared down, and swing the right prop, you'll probably never run it that hard anyway. You'll just get way, way more push.
It will take some time for folks to figure out which prop works best behind the aircooled reducted engines. I'm not sure that the ones running right now even have enough prop on them, but they will figure it out pdq. It won't take decades anyway.
Time and money is all it takes. One of these days I'll have more of each.
When I do, I'll get myself a reducted aircooled set up.
Perhaps it will be a chain drive Scotty!
