I've put a few covers on here signed by WW1 aircrew. Sadly I haven't much information on many of them. So if you happen to know any information, I would be really grateful for any help.
Cover signed by Adolph Jacobsen EK who was born on 28th of September 1895. It also seems to say Flg A bt 275 after the signature.
Cover signed by Kortum . Photo's of him are below. No other information at the moment , help!
Cover signed by Curt Muller who was born on the 21st June 1898, and flew the Friedrichshawker seaplane.