Profiling The Weird and Wonderful Aircraft of 1930s Soviet Aviation

Part II   The Stal'-6

Robert Bartini was a designer of very broad aerodynamical interests. Of Italian birth, he was responsible for many Soviet designs in the 1930s in the USSR, ranging from fighter aircraft to strategic bombers. However, all Bartini designs shared a common principle-- they were radical in lay-out and showed a perfect lack of concern for the 'status quo' in current aviation thought.

The Stal'-6 (meaning 'steel' -6) was of highly mixed and exotic metal construction (not surprisingly, given the name). The internal structure was of chrome-molybdenum steel tube framing, whilst the main portion of the fuselage (aft) was skinned with AltMag (aluminum/magnesium) alloy sheet. The cowl was skinned variously, with very thin magnesium alloy skinning on the under surfaces, Electron alloy skinning on the uppers, and burnished steel covers for the cylinder heads. The wings and fillets were skinned in thin stainless steel sheet. The vertical stabilizer was skinned in birch ply laminate. Unusually for a Soviet aircraft, the Stal'-6 appears to have completed the majority of its testing and evaluations in an unfinished condition, with only a coat of 17A clear sealant to cover the structure.

Performance in the radical Bartini design was quite good. 420 km/h was achieved at sea level, and handling in the air was judged to be quite competent. However, as a military design, one wonders if the project was ever really a serious contender. Despite the generous statements made by Yumashev about the odd single gear and skid system, one would have serious reservations about recommending this arrangement for actual service use. Moreover, one must mention the vulnerability of the surface evaporation cooling system in any military context, and indeed Stefanovskij noted that visibility forward, made through a 'binocular tube' system, was strictly limited. Finally, would such highly exotic and expensive materials be suitable for mass production? We shall never know; the Stal'-6 was not selected for manufacture, and a larger version known as the Stal'-8 never progressed pass the design phase.

The Stal'-6 at the NII VVS for evaluation. Note the original semi-enclosed canopy, and the glossy unpainted surfaces.

The aircraft as tested at the NII VVS. Gear is shown in the extended position.

Front view of the Stal'-6 showing the single gear and skid arrangement. Note the binocular view ports.

Stal'-6 as shown later by VB Shavrov. A hinged, fully-enclosed canopy was added, and the aircraft appears to have been painted uniformly over-all.
The lacquer shown here is AEh-9, which seems a likely choice. The landing gear is shown retracted.