This was a special-order Radial Flyer in MAC Performance 54mm tube.  The Radial Flyer is normally offered as a 3" or 4" kit, but I asked Mike for one using his 54mm tube.  At the time of this writing, this is the only one in this size that exists. I added to that a 3D printed boat tail of my own design, lending the appearance of the Aero Pack boat tail motor retainer that the larger ones are designed for.  This has a 29mm motor mount and a 36" parachute.