Flamers

What was the main cause of flamers ?. Did the magneto keep sparking even when the engine was switched off because the prop was still windmilling ?. Was there any difference with rotary's and stationary engines as far as the volutility of the fuel oil mix in the rotary's ? . Did the fuel ignite on some occasions because of comming into contact with the hot exhaust manifold ?, or was it more from an ignition system spark ?. positioning of the fuel tank must have played some part , with this positioned infront of the pilot ( i guess ) on most tractor aircraft , was there any models that were more prone to " going down in flames " . The use of Balloon buster and tracer ammunition played some part also I guess . Do the formites have any imformation on this matter .
Thankyou for any imformation .