Forbiden thingies
I recall a movement that was "interesting" in the Chippy, though nothing as clever as this lot, called the Porteus . One entered a stall turn about ten knots faster than usual and at what would be the stalling speed in wingborne flight full in spin rudder and elevator was applied causing a sort of spin but in the vertical plane, centralising when once round or thereabouts and then completing a fairly normal stall turn recovery Done nicely it looked good but felt horrible. It was supposed to be very bad for the airframe and was eventually banned.seems it caused many loose rivets down the back end