Clair Aubrey Huston (Bureau of Engraving and Printing)

Inverted Jenny, US 24c airmail error — Wikipedia: Inverted Jenny
Rarity: Rare
One of philately's most celebrated errors — a 1918 US airmail stamp with the Curtiss JN-4 "Jenny" biplane printed upside down. Only one sheet of 100 reached the public.
Paper, carmine rose and blue inks