This is a 1916 Sopwith Triplane. Reportedly, Baron Manfred von Richthofen, aka "The Red Baron, saw one of these during a battle and demanded to have his own, which was the Fokker Triplane. A volunteer guide told me the plane is quite unusual in that the engine rotates in sync with the propeller, so the only way to slow the plane down is to shut off the engine. That would make for difficult landing conditions, I'd guess!