Wankel and piston engines are ok, and their advantage is their relatively widely available
But, since the 2000, drones matured as surveillance platform. UAV should be more and more bring attack capabilities among the list of theirs features. Few small quided missiles on UAV like Shaheed 129 or Wing Loong are ok, but more is required on a battlefield with growing insurgency
UCAVs like Dassault Neuron, BAe Taranis are a perspective, of quite some time, due to the various reasons. And turboprops are generally "extension" of piston driven UAVs, since they share for example aerodynamical configuration, and some other features. Their payload, is twice and more heavier than the one of piston engine drones, enabling them to deploy even cluster bombs. That implies, they are capable of replacing conventional attack aircraft, with much lesser cost of deployment and more flexible use
Implying, since turbofan drones gain their maturity, turboprops should be the highest iranian priority
Just imagine tens of these drones hovering over syrian battlefeld, and striking them with cluster and tv quided bombs and proceed with surveillance, thereafter
Piston engine drones, cant provide bomb delivery, which turboprops can
