>>This means they can be connected directly to the propeller without a gearbox

With ICE prop-driven planes, it's typical to not have a gearbox - effective "gearing' comes from an adjustable pitch propeller.

Interesting that they used a Nemesis kit. I wonder if they considered a Falco (which also has good air resistance numbers - and is used (with ICE/prop) as a jet fighter trainer by a few air forces, albeit not ours).