08/31/2014. Remarks by Walter van Tilborg: "Development of the S-6 was started by the Stemme AG during the late 1990s and it was a new design (compared to the S-10) in several major aspects. Like in the latter, the engine was positioned behind the cockpit, but the propeller was now located in the nose in a more conventional (fixed) way. Wing folding was optional on the S-6. A first prototype aircraft (D-KTSA and representing the S-6RT version with retractable tri-gear) made the first flight on 29 November 2006.

Several variants of the S-6 were planned and by late 2007 two further prototypes (a second prototype and the modified D-KTSA) of the S-6T variant (fixed tri-gear) had flown. Stemme, but also other companies such as SAGEM France used the S-6 airframe as basis for UAV (Unmanned Aerial Vehicle) or OPV (Optionally Piloted Vehicle) special role aircraft. Production of the S-6 had exceed the 30 mark by 2013.

N622RT (c/n 22) was built in 2013 and registered in the name of Aircraft Guaranty Corp Trustee in Onalaska, Texas, USA."