minimalistic hand-drawn sketch on a notebook page. The sketch features simple, clear outlines of helicopter blades. Annotations are written in a simple handwritten script with arrows pointing to specific parts of the helicopter. The background shows faint notebook lines and subtle imperfections like small tears or smudges. The overall style is organic and sketch-like, with minimal shading and a focus on clarity and simplicity. Include a few brief scientific notes and a date at the bottom of the page, resembling an authentic scientist's notebook entry --ar 9:16
