X-Plane 10.20 – Douglas M-2 Mailplane. The Douglas M2 was a mail plane designed according to specifications of US Post Office. Western Air Express was awarded the Contract Air Mail 4 to operate between Salt Lake City and Los Angeles with a stop at Las Vegas. There was two forward compartments and hatches to carry 1000 lb of mail. Operations began on 17 April 1926. The plane could also carry two passengers on the same route. Credit goes to Bernard Augras for using his pilot. By Philippe Gastebois.