What is the principal advantage of using propeller reduction gears?

The principal advantage of using propeller reduction gears is to enable the engine RPM to increase with power. Reduction gears allow the engine to operate at a higher RPM while simultaneously reducing the RPM of the propeller. This is important because it allows the engine to develop more power and operate more efficiently without exceeding the maximum RPM limits of the propeller.

By allowing the engine to run at a higher RPM, reduction gears ensure that the engine can produce enough thrust while optimizing its performance characteristics. These gears also adjust the rotation speed to match the optimal operating range of the propeller, effectively maximizing thrust and efficiency.

While options related to engine reliability, weight reduction, and engine cooling might have their own benefits, they are not the primary purpose of reduction gears in this context. The focus of propeller reduction gears lies in enhancing performance through superior RPM management.