Those design parameters are my own, from many hours of experimentation. I wasn't trying to create a scale heli. The blade overlap is only by an inch or two and since the rear rotor is elevated by 2" - 3" and canted rearward, blade strikes are not an issue. It may sound strange but this configuration has much better movement authority and manages yaw better. I forgot to mention the rotors turn in opposite directions.
H design quads are not that uncommon. There are a number of them designed after airborne carriers copied from movies, as well as steam punk inspired designs. I was seriously thinking of designing my own steam punk quad. I have many years of model ship building experience. Here's one that's currently being worked on that also shows the carrier and other design possibilities: http://www.rcgroups.com/forums/showthread.php?t=1682868
. I think they are stressing the ship aspect too much, but otherwise it looks pretty cool. Why would you have lifeboats for an airship?