Well the Shark sub is based on a real mini-sub, but Herge exaggerated the Sharkiness a lot, it was about the only vehicle which he did "customise" freely. In The Calculus Affair Herge customised the bumper design of Eastern Bloc cars by giving them up-curved bumpers, to reflect the country's Dictator Kurvi Tash. Calculus's Moon Rocket was closely based on German Vera Lynne War V2 rockets, but with feet and fairings added to the 3 fins. I have just made 6 model Moon Rockets for Squeak to sell at her craft fair, a good use for old drum sticks and other scrap wood!