French pilot Sergent Léon Pierre d'Escoffier flew primarily with Escadrille 20 for a year from 14-April-17 to 20-March-18 and briefly with Escadrille 46 from 26-April to 28-May-18 and then the five remaining months through to the end of the war with Escadrille R XI 241.  He painted across the middle of the fuselage of his Caudron R.IV "Pequenina," an endearment to his Brazilian wife, seen below from the side and then seen with him standing at the front of the aircraft, second from left.  The next photo shows his "Pequenina II," a Letord.  This fabric and other souvenirs from his wartime experience he brought with him after the war when he moved to Brazil and this is likely from one of the other of his 2 aircraft.  On the reverse he stencilled a plea to his fellow citizens KEEP YOURSELF, FRENCH! THE BOCHES HAVE THE HATE OF YOUR RACE AND YOUR FREEDOMS." I found a published reference to this quote in the 21-June-1929 edition of Le Populaire in an editorial demanding that more French troops be sent into the Rhineland as well as another from 1924 but none earlier so it may have been added after the war. Thread count is approximately 78 threads to the inch, in the typical range for French aircraft fabric.  The distance from the center-line of the wing ribs is 16-1/2 inches or 42 cm.  The fabric measures 26-3/4 in by 9-3/4 in or 68 mm by 24.5 mm.  It is split about a third from the left of the top image.  The handwriting in the lower right corner appears to read  "des appietes places dessire du ecole d'aviation (G.D.E.) trouve en chartres en 1918" which translates roughly as "desirous seats of the aviation school (G.D.E.) found in chartres in 1918."