Hurts to do so but I have to re-jig the airframe in light of the fact that the batteries are likely now to be fitted to the overhead in the avionics dome of my 'flying phone-box', which frees up the under-seat space which seemed the logical place for them at the outset.
This reduces the dimensions of the structural airframe to 1000 x 500 x 500 mm, and allows space for one seated passenger. Replacing the bottom-end of this frame will be a frangible foam box that will double as both a stand and 'crumple-zone'.
Among the top three companies to have raised venture capital recently has been Volocopter. People forget ~ all to easily ~ that they used a gym ball as a means of such undercarriage in their prototype.
But if to works, it works. I read recently of an earthworks engineer who was most proud of the fact his company had underpinned the ramps connecting a freeway with... polystyrene foam: in shear it's like custard but in compression it's a cheaper and lighter form of cement.
This chassis is thus down to 24 pounds from 35 today, a figure Weight Watchers would be proud of.