|Wing Area||15.3 0m2|
|Wing Load (kg/m2)||100|
|Power load (kg/hp)||1.75|
|Speed at 3000m||(630km/h)|
|Takeoff Roll||(190 m)|
|Flight endurance||2.0 hour|
The Stal-8 was a more practical development of the Stal-6. It was slightly larger, main construction material was an aluminum-magnesium alloy (altmag). All joints were performed by point wielding or wheel-wielding. Cooling system, landing gear was same as on Stal-6, but cockpit was conventional and two 7.62mm guns were installed in the engine cowling.
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.