Hughes H-4 Hercules, Flying boat prototype in McMinnville, Oregon, United States

The Hughes H-4 Hercules is a silver-grey flying boat with a smooth metal fuselage and a wingspan of about 98 metres. Eight propeller engines line the wings, four per side, with dark blades tipped in yellow. Its tall tail fin carries the registration NX37602. The aircraft stands indoors on a polished floor, a yellow sign reading "HUGHES HERCULES" in front of it.

The H-4 was ordered in 1942 by the U.S. War Department, which needed a transatlantic transport for troops and cargo and, because of wartime aluminum restrictions, specified wood construction. Designated the HK-1 by Hughes and Kaiser, it was renamed the H-4 after Kaiser withdrew. Delivered in 1946, after the war, it flew once, on November 2, 1947, in Long Beach Harbor.

Critics nicknamed it the "Spruce Goose," yet the airframe was mostly birch, not spruce. The name stuck and now appears on museum displays beside the aircraft. Visitors can also see the registration NX37602 painted on the tail fin and a yellow "HUGHES HERCULES" sign at the fuselage.

The aircraft hangs above a mezzanine with wire-mesh railings and seating, so it is viewed from below and from the balcony level; look for the yellow "HUGHES HERCULES" sign and the "NX37602" marking on the tail fin. The eight four-bladed propellers, dark with yellow tips, sit above the wing on two nacelles.

Howard Hughes piloted the H-4 himself on 2 November 1947, lifting off Long Beach Harbor for about a minute and reaching roughly 21 metres. He kept the aircraft in a hangar for the rest of his life rather than fly it again.