<p>In the present article, the influence of multi-objective stochastical redesign of a small unmanned aerial vehicle (SUAV) having battery-powered electrical powerplant system over its control surfaces (i.e. elevator and aileron), powerplant system (i.e. battery mass, propeller pitch and rpm) and its automatic flight system (AFS) in order to enhance not only autonomous flight performance (AFP) but also maximum endurance is studied. For this purpose, a SUAV is manufactured in Erciyes University Drone Laboratory and named as Erciyes-Qtar-SUAV. Its control surfaces (i.e. elevator and aileron area ratio), powerplant parameters (i.e. battery mass, propeller pitch and rpm) and AFS parameters (coefficients of relevant proportional-integral-derivative controllers) can be changed before flight with respect to the multi-objective simultaneous and stochastical redesign stage results satisfying maximization of both AFP and endurance. A certain stochastic optimization technique (i.e. constrained simultaneous perturbation stochastical approximation: c-SPSA) is also applied for this aim. Obtained redesign consequences are beneficial in the simulation environment of SUAV autonomous flight. The principal substantial contribution of this research article is benefitting from the multi-objective simultaneous and stochastical redesign concept meanwhile obtaining optimum solutions of control surfaces, powerplant and AFS parameters. One more important contribution of this article is also implementation of c-SPSA optimization procedure for the aforementioned purpose. These substantial contributions also cause fuel economy and clean skies. In addition, almost 51.5% enhancement in total cost index, 59.5% enhancement in autonomous cost index and 17.4% enhancement in general flight cost index (i.e. including term relevant maximum endurance) are obtained for this stated battery-powered SUAV with respect to the situation in which multi-objective simultaneous and stochastical redesign concept is not implemented.</p>