Eben's helicopter

Eben and Luca stayed over Saturday night with us, giving Ruth & Josh a rare night out together (and a Sunday morning lie-in).
Both boys were relaxed and cheery. E woke up just before 6 a.m. but Luca slept in till just after 7.
Eben loves the wooden Brio building set and produced an impressive helicopter. This prompted an in-depth discussion between him and Richard, about why a vertical fin on the tailpiece (is that the right term?) is essential.