LEOPARD engines have proven to be robust and low-cost propulsion alternatives in helicopters, but also in gearboxes. They are manufactured in CHINA and are offered by us in the 700 series.
Their workmanship is absolutely satisfactory and they are true "price bangers".
When using them, it should be taken into account that they also work internally only with a 6mm shaft and bearings. Competitors use at least 8mm or even 10mm shafts and bearings here. This makes them susceptible to excessive shaft bending and bearing loads in the gearbox. For reduction ratios >= 3.60, the Power Expander should be used and only very light 2-blade propellers should be used.
As a "more robust alternative" the SCORPION HKIV-4035-560KV can be used.

A, under consideration of the above mentioned, real enrichment for gearbox applications.