View taken from below. Looks like AT-6. 28368N. Faint black marks on back, probably from contact with other cards, cetainly irrelevant. In flight to left. Plane similar to the one above.
Cards give technical specs on back.
These are NOT Postcards. Parked on the ramp. Aircraft carrying allied markings so probably a captured fighter being evaluated for performance after WW2. Real photo, modern repro. Real photo, modern repro.