I count 69 enlisted men and 3 Officers.
Ranging in age from 25ish to 45ish for the enlisted men and the Officers seem to be 40 to 55ish.
Several enlisted men wear eyeglasses so I think we can rule out pilots here.
From the smiles and grins on many faces it seems a happy time for them. (read early war) and no leaves on the tree in the background but several upstairs windows are open. Early Spring or Fall?
I know its not much help. But I would like to work on this if you don't mind? I have some buddies who might be able to help.
My first impression was it it was a Maintenance crew.
Growing up on or near U.S. Bases I saw a ton on similar photos of base personal.
If I had to guess I would say that's what this is and that it may have been taken just after the war started in 1939.
