German test vehicle. Subscale test model of A4 (V-2). Replaced the A3 in this role after its unsuccessful test series. The A5 used the same powerplant as the A3, but had the aerodynamic form of the A4 and a new control system. 25 all-up versions were flown, some several times.
Source :
http://www.astronautix.com/a/a5.html