Last Sunday, the bloke and I visited the Imperial War Museum at Duxford to geek gawk at the gigantic hangars full of military aircraft. We saw a "land machinery" demonstration, which was, as you might imagine, a bunch of overgrown kids (boys and girls, I hasten to point out), gleefully driving tanks through a very big mud pit while a Spitfire and a Hurricane spiraled overhead.
For some reason, though, this is my favourite photo from the day. It's an 80 hp Le Rhone rotary engine, used in aircraft during the first World War. A stark, symmetric form caught in bright cold light. Mmm.