The question has been asked:

What is the ventral fin & its purpose?

The ventral fin is installed on the bottom of the fuselage to reduce adverse yaw. With the reduction in adverse yaw comes a reduction in rudder authority. This is really not much of a problem with the Cheetah XLS since it has a lot of rudder authority. The Ventral fin is not required and this is why we have it listed as an option on the pricing sheet.



Note the ventral fin on the bottom of the fuselage.

Thanks,
Steve