A few illustrations for the Film 'Three Musketeers'. More sample images are on my website.
Although I doubt that Leonardo would have designed an airship the way it is shown below, the idea behind it isn't as far-fetched as one would assume...
In 1783 the Montgolfier brothers had made a public demonstration of a hot air balloon in order to establish their claim to its invention.
King Louis XVI proposed to launch two criminals, but it is most likely that the inventors decided to send 3 living beings, not the Musketeers :) but a sheep, a duck, and a rooster. The flight lasted 8 minutes, covered two miles, and obtained an altitude of about 1,500 feet.
