Still looking for what I have (in the manuscript I have on Pegna's projects the table with flying wings is missing, grrrr). Anyway, here is what I can say out of memory:
the illustrated project is from 1928, it was a seaplane BOMBER with a deep V-shaped hull that doubled as a ventral fin, there were two lateral floats, retractable in the wings, the engines were three, buried in the wings and fuselage. Tested as a model in the windtunnel. Preliminary design only. Piaggio didn't have the structural skills to build it (nor Pegna had the structural engineering experience to design it...). Dimensions were: span m 39.5, lenght m 12.6, height m. 3,65. The preceeding year, 1927, Pegna designed a larger flying wing, even less feasable. It was a transport seaplane with two unspecified engines in wing nacelles and wing floats under them. Span m. 80.0, lenght m 23.5, height m. 12.