The fly in the ointment for the GoFly challengers is actually safety. The go-karts we built as kids out of pram wheels and pallets wouldn't have met the road safety regulations applicable to the those we ran down at speed, and from the same point of view were I to be building one of these things to fly around a field it would have four large motors and four large propellers.
Such motors however are wilfully overpowered if they are going to be doubled in number to satisfy redundancy requirements, which is a pity because all aircraft evolve into types with the least number of power-installations that still satisfies safety. Thus jet airliners devolve into twins, and helicopters most benefit from two engines driving the largest rotor.
Drones are a little different, for while there are tri-copters out there the structural simplicity of quads tends to make them the more popular. All design is a trade-off and there are good arguments here ~ though there can't be many teams still drafting final outlines ~ for using more motors driving 32-inch propellers.
A benefit of my underlying outline is that independent modules can be stacked ~ at an offset as above or coincident as below. The first is more aerodynamically efficient, the second more structurally efficient. In both cases though the safety margin between my body-parts and the rotating parts is thankfully greater.
I've always been a structures man whenever a choice has to be made, as now when the time for spending hard-earned cash for equipment is upon us, so we take forward that one here:
