Measurements of lift, drag and pitching moment have been made in the. No. lA Wind Tunnel at the College of Aeronautics at a speed of 132 f.p.s. on a model rocket supplied by the Armament Research Establishment, Woolwich. The model was tested with three different tail spans, and with no tail. The tests made showed that the increase in static stability was almost directly proportional to the net span of the tail fins. For small angles of incidence the fin effectiveness was the same for the fins mounted vertically and horizontally, and for the fin assembly rotated through 45°. The model vas found to be statically stable about its point of suspension for all three fin sizes, and no unsatisfactory characteristics were Observed over the test range of incidence from -12° to +18°. The experimental results have been compared with estimates based on slender body theory.