|Engines||1*660hp Curtiss V-1750 Conqueror|
|Wing Area||14.3 0m2|
|Wing Load (kg/m2)||77|
|Power load (kg/hp)||1.6|
|Speed at 0m||420km/h|
|Flight endurance||1.5 hour|
Experimental fighter, far ahead of its time. Leaving alone its steel (so Stal) construction, following features are to be mentioned:
Stal-6 successfully passed all tests during Fall 1933. Pilots A.B.Yumashev and P.M.Stefanovskij proved that 'one-wheel' landing gear is as good as conventional on takeoff, landing and taxi. Speed on ground level was 420km/h, 150km/h faster than typical speed of contemporary fighters.
Interestingly, that VVS authority already pushed aircraft builders to increase speed of their aircraft, but faced 'organised resistance'. Manufacturers did not believe that substantial speed increase is possible in short time. They interpreted rumors about Stal-6 as a 'duck'.
On official meeting with K.E.Voroshilov and G.K.Ordzhonikidze representative of the GUAP tried to prove that fighter with speed 400-450km/h is impossible. He was corrected that such aircraft (Stal-6) already exists and its designer (R.L.Bartini) is present on the meeting.
There was a widely used argument against evaporative cooling systems - vulnerability. But... this is a common feature of water-cooled engines (except special cases with armor-shielded cooler like Il-2). Large area of cooling surface is not a weakness - higher probability of combat damage is compensated by relatively lower impact of a hole on the system.
During trials of Stal-6 A.B.Yumashev performed few flights with imitation of a cooler combat damage. Each flight lasted more than 30min! Taking into account that flight endurance of (most) Soviet WW-II single-engine fighters was close to 1hour, damaged fighter could not only return home safely, but do it after the fight is over.
There also was a room for improvement - Stal-6 had single-unit cooler, while segmented system could be even less sensitive to damage.