Dick, I don't want to be contentious, but could you point me to a link, article, or aeronautics text book that say any of those maneuvers are impossible, as you state? I am asking this, because not once in my career have I encountered a fellow aeronautical engineer, a text book or an article in a journal stating any of the maneuvers you are refering to cannot be done. In fact, one of the areas in which I work is fighter flight dynamics and there are hundreds of papers in my collection on so-called "super-maneuverability" - and some of those go back to the 70's (although the term wasn't used until the 80s as far as I know). This was long before "3D" became popular on R/C models.

And for what its worth, the maneuvers performed by the Su-30 are done at low speeds and the G-loads are therefore not very high at all... The G-loadings become an issue when maneuvering at higher speeds. A steep turn above the maneuvering speed of the aircraft typically puts a much higher load on the wings than the tumbling maneuvers you see done with the aid of thrust vectoring.