Shoot flat acrylic clear and let it dry and cure overnight. Get some artist yellow ochre oil paint and make a very thin wash with turpentine. Use a wide soft brush to apply the wash. When it dryes it will resemble a sun bleached effect on the paint. Go easy with the yellow ochre cause it will overpower the effect.
I went a little heavy here but I wanted the Stuka to show the effects of the hot North African sun.