The ASRO 3T was used to develop the ultralight side-by-side two-seater ASRO 4. Of welded steel tube construction covered with light-alloy, it had a fully enclosed fuselage pod and tapered tubular tail boom. It was fitted with an 130 shp BMW 6012 turboshaft mounted behind the rotor gearbox driving three-blade main and two-bladed tail rotors of composite construction. This machine flew in May 1964, and was tested for some while before being abandoned without achieving certification."