The Transavia PL 12 "Airtruck" was demonstrated at Sun 'N Fun in Florida (U.S.A.) many years ago. In spite of being the ugliest airplane I have ever seen, it was a clever design around an insecticide hopper for easy loading and very safe with the cockpit sealed off from the insecticide area. The military significance was a design for evacuating stretcher patients. You have a great Museo del Aire at Cuatro Vientos.