One has to be fairly optimistic when you see it was possible using an aero model...............I know its now, but the Germans at the time of WW2 were desperate for any solutions.
Fitted with the right fire power, I would wager no Allied aircraft would have had a hit on such a spherical object.
Ground fire a different thing of course.
This video just shows what an aeromodeller could do and many of the NAZI Scientists admitted after the war thats all they were!!!!!!!!