The "White Foam" : can come from any aeroplane on a random basis, its a straight out graphical glitch
For those that haven't seen it here it is on Youtube at 3:09 and a still from the vid:
In this case a Spitfire after a slow snapshot. However it is not always associated with action it is a random event ... I have witnessed aeroplanes "foaming" as they go into the flare.