After the supply of Wac Corporals was exhausted, the Caltech team returned to their drawing boards to develop an improved rocket, the Wac B. Through changes in materials and design, the engine was lightened from 50 to 12 pounds, the structure of the missile was modified, and a new 5-channel telemetry system was added. Externally, the most obvious change seems to have been the replacement of the conical nose with an ogive payload section. About a half dozen Wac B vehicles were flown in Dec. 1946 and Feb. and Mar. 1947 by the end of the Wac Corporal test program. One Wac B, launched from White Sands on Feb. 17, 1947 reached an altitude of 45 miles.