[burns]

Correct noseart format is 256x512 bitmap, that is, like two squares one above the other. The fact is, images in the upper half will appear on the LEFT side of the plane, while the lower half will be shown on the RIGHT side. "Stock" nosearts have the image on the upper part, but there's nothing preventing you from editing the file to make it appear on the right, by placing the image on the bottom.

When I try 256x512 I get two images, squashed, on the left side and none on the right side. This was tried on the Spitfire Mark IXe.