I remember seeing this sketch on the cover of the old Hobby Horn catalogue years ago.

Thomas, you are right. And if you look real close to the landing gear axle on the left side you will find the artist's initials "PB." I believe that means "Phil Bernhardt", his father was the source of the most beautiful ignition conversions known to mankind. Phil was the last editor of "Model Builder" before circumstances overcame the Northrops and they folded the magazine.  Ned Nevels