In the early part of the war most aviators had to improvise with what they could find or buy, mainly from motoring catalogues. Later in the war, the best aviation garment was the one-peice Sidcot suit, invented by Australian aviator Sidney Cotton. This was so good that the Germans were not above wearing captured examples. Later versions had internal electric wires for heating (remember to switch off during take-off and landing and in combat!) and continued in use until WW2. http://www.germanmilitaria.com/OtherNations/photos/C22454.html Sidney Cotton, who allegedly refused to profit from his wartime invention, was one of life's extrovert characters: http://en.wikipedia.org/wiki/Sidney_Cotton Incidentally, the picture of Rickenbacker in Annie's second post above is a well known one showing him with a German Hannoveranna CL.IIIa that he forced to land. The picture of Manfred von Richthofen shows him with his taller younger brother Lothar. The other (left) picture I don't think shows anyone famous, but the aircraft is a Caudron G.III with an Anzani radial engine, so probably taken at a training establishment.
It would have been just too unbearable to be seen wearing the same outfit twice! Slightly more seriously, German officers seconded to the Air Service continued to wear the uniform of their original regiment and hold equivalent ranks. So MvR's usual uniform would have been that of an Uhlan, a type of Cavalry regiment. His rank of Rittmeister was equivalent to a British Captain in a cavalry regiment, or a Hauptmann in the German infantry. German officers were not promoted when given more responsibility, so he was only ever a Captain, even though as a commander of a Jadgeschwader of 60+ aircraft he would have been at least a Lt-Colonel if in the RFC. But for flying, he certainly had a nice line in leather jackets!
