POLISH C.S.S. 12. Design work on Poland's second post-war feeder-liner began in Warsaw in 1948 under the general direction of Prof. F. Misztal, a pre-war member of the P.Z.L. design staff. Two years later the ten-passenger C.S.S. 12 (SP-BAR) began a series of test flights which continued on into 1951.
Prof. Misztal was also responsible for the two earlier phases of the C.S.S. programme, namely the design and manufacture of primary trainer and aerobatic prototypes. This resulted in the C.S.S. 10A (1948) and the C.S.S. 10C (1949) primaries and the C.S.S. 11.
Salient features: In the same class as the French Sud-Ouest SO.94R and tailwheel SO.95 Corse 11 (and using ·the same basic Argus 12-cylinder inverted-vee inline "power eggs " ), the C.S.S. 12 bears a superficial resemblance to the smaller and lighter D.H.104 Dove/Devon series of feeder-liners. The unusual plan-view shape of the nacelles is due to the forward and sideways (through 90 degrees) retracting main undercarriage legs which, like the backwards-retracting nosewheel, and the double-slotted, camber-changing flaps are hydraulically operated.

POLISH C.S.S. 12. Data: Manufacturer: Centralne Stadium Samolotow of Z.P.L. (United Aircraft Industry), Warsaw, Poland. Powerplant: two 580-h .p. (390 h.p. at cruising altitude of 8.500 ft .) Argus As 411 TA air-cooled inlines. Accommodation : ten plus two crew. Dimensions: span 60 ft. 8t in.; length 41 ft.; height 16 ft . 9 1/4 in.; wing area 431.636 sq . ft.; assect ration 8.53 . Weights: empty 7.717.5 lb.; payload 2.205 lb.: loaded 12,127.5Ib . Performance : maximum speed (at approximately 8,000 ft .) 226.67 m.p.h.; cruising speed (at 2/3rds t.O. power) 198.72 m.p.h. at 8.500 ft.; minimum speed 62.1 m.p.h.; climb rate (maximum a.u.w.) 1,280 ft./min.; service ceiling 19,692 ft .; range 745 miles.