Model Variants (Including Prototypes)
D.I - Base Military Designation; based on 8D1 prototype; limited production figures.
7D1 - Initial prototype model; plywood skinning; upper wing-mounted radiator (portside); comma-style rudder assembly; I-struts.
7D2 - Based on 7D1 with vertical stabilizer added.
7D4 - Based on 7D2 but with radiator relocated to central wing area; conventional strut works; fabric skinning at fuselage.
7D5 - Variant
7D7 - Based on 7D4; I-strut (thinner than previous); simplified wire works; new radiator located closer to nose.
7D8 - Based on 7D7 with even more simplified wire works.
8D1 - Finalized prototype becoming the D.I in serial production.