I'm not quite sure which category this falls under but as there are a lot of scale applications, I thought I tell you about it here an post in fuel heli classifieds
I was asked to build a heavy lifter proof of concept for a company. I used an Xcell gasser frame, G26 motor TSA 3 blade head and 800mm NHP carbon blades. The tail was Vario with a metal gearbox.
It was flown twice, first with 43lbs hanging under it to show it could lift that much and second with 100cc of fuel in it and 40 lbs under it to see how long it would fly for.
The motor these guys wanted to use became unavailable so the project ended and they dumped the heli on me and forgot to pay me.
So, I'm selling it cheap as its a collection of parts, but did fly well.
If you are into gassers take a look in fuel heli classifieds and be surprised at how little I want for it