Be sure to check out Farre's book "Sky Fighters of France"
Amazon.com: Sky Fighters of France (Flight, its...
Originally published in French - the link above is to an English reprint (images are in black and white). This book is Farre's adventures and wonderings from escadrille to escadrille during WWI where he painted pilots as well as air-to-air action - some based on interviews with the pilots, some based on his own flights as a passenger. It is a great read.
Also know that after the war, there was a tour of Farre's paintings in the US to benefit orphans if French fliers from the war. I have a program from the show in Philadelphia, but I know it was also in Boston and Chicago and I can only assume New York.
Yes, the Air and Space Musuem has some quantity of his WWI painitings, but few are in display in the public areas. Several I have seen are hanging in conference rooms in the administrative area on the third floor.
Thanks for sharing these wonderful paintings.