blackkite said:
Perhaps these aircraft are not candidate (...) G6M1-L and H6K2-L were planned
One must bear in mind the chronology here:
L4M1 competition unknown but ordered circa 1937-38 >> procured as Type 0 Transport in 1940
L7P1 13-Shi Small Amphibious Transport ordered 1938 >> not procured
As these two types were ordered during the 1937-38 period, the L5 and L6 that were in-between are bound to have been 1937-38 types too. That makes it impossible for the wartime Ki-92 or Ki-105 to have been candidates!
I first thought the Gasuden and Hitachi transports were interesting suggestions because they fitted in the time sequence and were rather similar in configuration to the L4M1. One can imagine that the L4M1 may have quickly proved unsuitable for the Navy's needs and that the other two types were therefore not ordered as initially planned... However, if all three aircraft had been submitted to the same tender, in all logic the two other candidates would have been L4 as well, NOT L5 or L6!!!
And so in all logic, being contemporary with L4 (land-based transport) and L7 (amphibious transport), L5 and L6 should have been competitions for DIFFERENT types of transports (carrier-borne? flying boat?). That makes the Kawanishi H6K2-L/H6K4-L (Transport Flying Boat), the Nakajima G5N2-L and maybe also the Mitsubishi G6M1-L/-L2 (Large Land-based Transport) possible candidates that could have been redesignated along the way. So far it seems to me like the best bet as to why L5 and L6 are so conspicuously absent from all records...