The glider instructor I mentioned earlier was Derek Piggott and this is what wiki says about the Blue Max.
Pilots from the Irish Air Corps helped recreate the live dog-fight scenes, supported by number of civilians, including Charles Boddington and Derek Piggott. Piggott was the only pilot willing to fly beneath the spans of a bridge. Taking the role of both German pilots and with multiple takes from contrasting camera angles, he ended up flying 15 times under the wide span of the Carrickabrack Railway Viaduct in Fermoy, County Cork, Republic of Ireland, and 17 times under the narrower span.