Excerpts from Hayao Miyazaki’s Daydream Notes (aka Daydream Data Notes). Miyazaki had a regular feature in Japanese hobby magazine Model Graphix where he’d make various short comics and illustrated essays on vintage aircrafts, tanks and boats. It was also where he published the short comic "The Age of the Flying Boat", which he later reworked into his film Porco Rosso.
You can find some more scans here. Halcyon Realms has a review (with more scans) here.