Hello,
Yes, the relative paucity of information about Loewenhardt is frustrating - along with the lack of photos. He never wrote any memoirs or letters, etc. that have been preserved (as far as I know - outside of an essay on how to attack balloons). We only really know anything about him from what others wrote about him, and there's not a lot of that. Apparently his family was not interested in publicizing his exploits.
I suggest you get ahold of
Over the Front, Volume 29 Number 3, Fall 2014. It contains a well-illustrated reprint of an article entitled "Loewenhardt's Seventh." The article originally appeared in
Popular Flying of March 1938, and was written by Lt. Bertram B. Perry of No. 22 Sqdn RFC. Perry was the pilot of a No 22 Sqdn Bristol Fighter that was shot down behind German lines by Loewenhardt on 18 October 1917. Perry and his observer met Loewenhardt and his fellow Jasta 10 pilots (especially
Hans Klein and
Aloys Heldmann) and they were entertained and feted at Jasta 10's airfield before being taken off to POW Camp. Perry was a journalist by trade, and his account is full of fascinating details and insights into Loewenhardt's character and personality
Also, the Baroness von Richthofen's book (translated into English as "Mother of Eagles") has a very short but interesting vignette about a chance encounter she had with Loewenhardt on a train.
I would highly recommend Lance Bronnenkant's book
The Imperial German Eagles in World War I, Their Postcards and Pictures, Volume 2. It has one of the best available brief biographies of Loewenhardt, along with a number of rare photos.
Greg