you also need to take into account that when you loose an engine you're not going to loose thrust from that engine but also the symmetric one on the other side. for example if you number engines 1-6 in clockwise order, if engine 2 cuts out you will have to shut down or reduce thrust in engine 5... unless, of course, you think flipping over would be fun... but i suspect not lol. also i saw no consideration in your weight estimates for for fuel... considering how light your craft is, it could make up a significant portion of your weight buildup.
fule can be 5kg for testing and if any engine/s is out all the other engines will compensate by lowering the rpms a little for perfect rebalance.
Mollers are too loud but he didnt use 32 inch props
I read that you got 100kg out of a kawasaki 25hp what was the gearing do you remember perhaps?