This engine is a direct descendent of the Whittle W I/2B series. General Electric improved upon this engine under the engineering team led by Donald F. Truly Warner in April 1942. Two of the first GE series I-A engines, developing 1,250 lbs. Thrust each powered the Bell XP-59 in October 1942.
Progressing in thrust through the series 1-14, 1-16, 1-20 of 1,400, 1600 and 2,000 lbs. The J33 began life as the 1-40 in June 1943 with Dale Streid heading the engineering group. It was first tested at 4,200 lbs. of thrust during Jan/Feb 1944.
First flight was June 1944, in an XP-80A. The production engine was designated J33 with GE building 300 before the program was transferred to Allison in Sept 1945.