Evil Twin?
According to articles by Derek Piggott, Bob Rodwell and others in "Sailplane and Gliding" & "Pilot", Edgley volunteers that he used the Ka-18 as the basis for the design of the EA9, as he wanted to prove the structural properties of the Fibrelam material, and not have to design and debug the aerodynamics of an entirely new glider. However, the wings were slightly clipped to 15.7 metres (from 16m) and the wing profile was was slightly changed/updated from a modified NACA 633 (with Wortmann leading edge modification) to a full Wortmann profile FX61-184 at the root and FX60-126 at the tip. Apparently some of the fittings on the prototype were actually salvaged from a Ka-18 hulk, so the resemblance is not just on the surface.
Wonder what the cost of the kits would be nowadays......