After 210 P-38Es were built, they were followed, starting in February 1942, by the P-38F, which incorporated racks inboard of the engines for fuel tanks or a total of of bombs. Early variants did not enjoy a high reputation for maneuverability, though they could be agile at low altitudes if flown by a capable pilot, using the P-38's forgiving stall characteristics to their best advantage. From the P-38F-15 model onwards, a "combat maneuver" setting was added to the P-38's Fowler flaps. When deployed at the 8° maneuver setting, the flaps allowed the P-38 to out-turn many contemporary single-engined fighters at the cost of some added drag. However, early variants were hampered by high aileron control forces and a low initial rate of roll, and all such features required a pilot to gain experience with the aircraft, which in part was an additional reason Lockheed sent its representative to England, and later to the Pacific Theater.