Dear Hannes,
The sources of the two parachute jumps are as follows:Eagles of the Black Cross by Walter A.Musciano, whose book was the first that I found any significant information about
Josef Jacobs and piqued my interest in him.He describes the incidents much as I have written it above,except he claims that Jacobs used a parachute in both collisions to save himself. Another account comes from Air Aces of the 1914-1918 War; edited by Bruce Robertson.In this book, the German pilot info was credited to Heinz Nowarra. In that book,the collisions are described in the same manner,but implies that Jacobs used a parachute to escape one of these incidents.Your comments about other pilots' parachute jumps intrigued me,so I checked them out.Unfortunately, I cannot locate the claim that Jacobs was the only WW1 pilot to survive two parachute jumps, but I will continue to look for it. I do not believe that he personally made such a claim,but that the accomplishment was attributed to him by others. I have no info on Vogel,but if true would also make him a "Jump-Meister" of WW1. However, I can give you specific info on Bäumer and Udet.On 17.8.1917,
Paul Bäumer shot down an English Bristol fighter for his 30th victory.During the fight,his plane was damaged by gunfire from another Englishman. As he began to lose control of his plane, Bäumer used a parachute to escape. This account is also from Eagles of the Black Cross. In early 1918,
Ernst Udet was shot down by a French Bruguet B14 and saved himself by parachute.This was described in German Aircraft of the First World War;by Peter
Gray & Owen Thetford.Hope this info is of interest
to you. GEJ
P.S. Perhaps you can help me locate the village of Kreutzkappelle(sometimes spelled Kreuzkappelle)
that is believed to be the birthplace of Josef Jacobs.Some references place it in Rheinland -Palatinate.A German friend once told me that he thought the village was north of the Mosel somewhere between Trier and Koblenz.Thanks, GEJ