Good question, the same year as the photo for the beginning of the design of the A-20, in general lines of its shape (of course I am not a specialist) it reminded me of this other design that I once found in worthpoint, single engine Severski VB-VT, unfortunately The information about it is not clearly visible in the photos, the image on the right is my perspective correction.....source:https://www.worthpoint.com/worthopedia/seversky-proposal-class-vb-vt-516210023