The Kl 31 was a four-seat touring aircraft of mixed construction, something of a novelty for Klemm. Thus development took some time and the wooden three-seat Kl 32 was built for the 1932 Challenge International de Tourisme instead. A series of thirty-six Kl 31s was produced between September 1933 and September 1934. D-IDUM was apparently a Kl 31a XIV model, with XIV referring to the Sh 14 radial engine, but became HA-NAB in Hungary and was then designated as a Kl 31B. HA-NAB impressed as I.814. Photo from: Klemm