Question about RC helicopter vs quadcopter efficiency with payload
I'll preface this with the fact that I have almost no experience with RC helicopters. My experience is mostly with fixed wings and multirotors. The situation is I need a platform to carry a 1kg payload for roughly 1 hr. Additionally, a dummy weight equal to the battery weight also needs to be carried. The entire craft cannot exceed 5kg. It would be flying a fixed path circling a point at a radius of 1/4km at an altitude of 100-200ft agl. In the past, I used a fixed wing platform with a 6s 10,000 mah lipo but new restrictions have limited me to exclusively rotorcraft. I understand that most helis are for acrobatics and have symmetrical rotor blades. I am willing to pay for custom fabricated non symmetrical blade(whereever I can find those).
My question is, with more efficient rotor blades, can how feasible is it for a heli to be able to perform the task? Also, where are some good places to look for semi-symmetrical blades or people willing to fab these blades.