Mark T.
A combination of
Who Downed the Aces in WWI by Norman Franks, "Hunting with Ricthofen, Bodenschatz Diaries" translated by Jan Hayzlett, and an "Over the Front" article titled "One Step Closer to Hauptmann, The Last Flight of Oberleutnant
Kurt Wolff" by S.A.H. Henderson (Vol. 13, No. 3 Fall 1998):
Karl Bodenschatz wrote that the afternoon of 15 Sept. 1917 to be "heavily overcast, moderate visibility". Wolff in his triplane (102/17) with a patrol of Albatros Scouts departed at 16:30 (German time) towards Menin for the last flight of the day. Naval 10 took off at approximately the same time at 15:50 (British time) led by Fitzgibbons with a patrol of Sopwith Camels (including MacGregor). Also up in the air at this time was No. 70 Squadron RFC, some distance away from Naval 10 at a slightly higher altitude.
Wolff and his patrol became separated in the overcast sky. Wolff flew along the Front looking for the rest of his patrol.
At approximately 1610 (British time), Naval 10 comes across 5 D.H. bombers and escorts them back safer territory. During this time, Jasta 11 Albatroses have a brief encounter with No. 70 Squadron about 10 miles from Marckebeke. It is believed that this brief tangle is when Wolff came back in contact with his patrol. Apparently the Jasta 11 vs. No. 70 Squadron encounter did not last long, but this isn't clear. Naval 10 arrives on the scene. MacGregor reports that they fought "four" enemy Triplanes, but there were only two Triplanes at the Front at the time (the other one belonging to Voss as Rich Hicks wrote). It's been theorized here that Wolff's manuevering in and out of clouds may have given the appearance of more than one Triplane. According MacGregor's combat report, it appears that he may have managed to catch Wolff off-guard as he wrote that he managed to get close at a good 25 yards and "fired a good burst" into what I’ve read as being fired into the cockpit before having to climb and turn to avoid colliding with the Triplane. The Triplane was then seen to have a nose-to-the-ground vertical dive towards the fields of Flanders.
Regarding the crash itself, one story that hung around for years was that when the plane slammed into the ground, it exploded into flames as you had written As Rich Hicks wrote, there is a photograph of a German infantry recovering Wolff's remains from a smashed but non-burnt Triplane. Bodenschatz further reported "Casualty: Oblt. Wolff (leader of Jasta 11) 5:30 p.m. north of Wervicq, shot down in air combat. Aircraft: Fokker triplane FI102 totally consumed." Bodenschatz didn't mention any fire as he had done in other writings regarding burned planes.
Hope that helps some.
Amy