cakes200:
Thank you for your research, Jock123
You are welcome - I've always liked what I have seen of these images, but probably not paid enough attention to how and why they were produced; funnily enough, only last week I was making a brief note to do something about that, and lo and behold, this week I have a reason to!
And here's one of the little details I like about how things come together in the world of Hergé which I don't think anyone has mentioned this before, so it's a fragment of original research, and possibly worth mentioning...
In
Calculus Affair, Tintin famously holds a copy of a (real) book, Colonel Leslie E. Simon's
German Research in World War II, which shows a German rocket in the red-and-white colours now connected with Calculus's moon rocket. It also shows the outline of a small 'plane, which in the real world had a swastika on it, but which Hergé removed in his version. So far, so good.
In the
Companion is said to be a prototype Messerschmitt, but this is a mis-identification: it is in fact a Bachem Ba 349 "Natter" ("The Adder"), a somewhat unlikely prototype rocket-plane, built partly of cardboard, and which unfortunately (for them) killed its three test pilots before the end of the war brought trials to a halt.
Although the cover appears to show it with under-carriage, it had no wheels, and is in fact pictured on its transport bogey, from which it was removed before flight.
It was then set in an upright position (like a moon rocket) on a rail, and fired into the air, nose first, pointed in the general direction you wanted it to fly (as it wasn't very easy to steer); it was then supposed to land on skids on its belly (it was the landings which killed the test pilots, so no wheels was not a good idea!), or, perhaps even more scarily, come apart, releasing a payload, then letting the pilot and parts of the vehicle's body parachute to the ground, to be re-used in future flights (this never worked!).
More interesting perhaps, and directly relating to Tintin, is that this particular model of 'plane, in spite of never seeing active service, was drawn by Studios Hergé as one of the
chromos for their
History of Aviation, 1939-45 series, where it appears to be flying better than it ever did in real life!