Used spoilers for roll control; small ailerons provided "feel" to pilot. Initial production delayed because of radar development problems. A models appeared near end 43 and went into service early 44. B model had underwing pylons to carry bombs or additional fuel tanks. Glossy black paint selected after being tested against dull-black and earth camouflage paints. Observers on the ground, during night tests, tried to determine which of the 3 paints were least visible in path of a searchlight; unlike others, glossy black paint refracted its rays so aircraft was almost indistinguishable.