Some more happenings - yesterday, our squad was fighting another squad in Mindanao, and since one of them was a dedicated P-47 flyer I had a chance to fight him again and again.
He was shot down in all of the five engagements, two by myself, three by my squad members.
All squaddies and myself confirmed that the first shot/ping landed that was visible, immediately caused the fire and smoke.
Ofcourse, some of the rounds may have bounced at not damaged the plane, but one thing for certain, is all five cases where he was shotdown, was caused by fires.