The Largest Flying Boat Ever Built

The H-4 Hercules, aka "Spruce Goose." Federal Aviation Administration (public domain)

The Spruce Goose in the main building of the Evergreen Aviation & Space Museum. Drew Wallner (cc by 3.0)

The Spruce Goose side view Moody 75 ( CC-BY-SA-2.0)

The Spruce Goose righthand wing Moody 75 ( CC-BY-SA-2.0)

The Spruce Goose Unknown (PD-SDASM)

Loft Socks

Onboard Fire Suppression System

Aux support beams installed by Disney under the flight deck

Cross section showing wooden construction

Howard Hughes's air filtration system and circular staircase to access the flight deck

Flight Deck

Co-Pilot's Station

Radio Operator's Panel

View of the Port engines and wing from the pilot's hatch

View of the Starboard engines and wing from the pilot's top hatch

Pilot's Position

Log book showing the one and only flight

Looking aft down the tail

One of the beach balls found inside the wing floats

View down the interior of the starboard wing

APU (Aux Power Unit) used to start the engines onboard the flight deck

Pilot's Instrumentation

Secondary Flight Engineers Panel

Inside the Spruce Goose jill, jellidonut... whatever (CC BY-SA 2.0)

Engines of the Spruce Goose scattered1 (CC BY-SA 2.0)

Aux Oil tank mounted just inboard of the port wing

Pilot's secondary panel

Flight Engineers Panel

Theoretical cargo arrangement

Hatch to access the fuel tanks

The Hughes H-4 Hercules, otherwise known as “Spruce Goose,” hatched from the need to transport World War II soldiers and supplies without the risk of being sunk by German U-boats. In 1942, the American shipbuilder Henry Kaiser took on this necessary innovation by looking to the skies.

Kaiser recruited Howard Hughes, a pilot, engineer, filmmaker, and millionaire to help design a flying boat that could airlift the cargo. Given the government restrictions on building materials during wartime, Hughes had to be resourceful, yet he was able to build an aircraft six times larger than any aircraft of its time without the use of aluminum or steel. To Hughes’ dismay, the press continued to call it the “Spruce Goose” even though the wooden mammoth is mostly made of birch. (The “Birch Bird” really is almost just as good.)

As Hughes was a notorious perfectionist, the engineering feat was still unfinished by the end of the war. Kaiser dropped out of the costly project, but Hughes continued to slave over his creation, egged on by his pride and the press. Many believed the plane would never fly.

On November 2nd, 1947, during a taxi test off the coast of California, Hughes impulsively piloted his Herculean airboat. It flew for about a mile, only hovering 70 feet above the water, but it still flew. The plane was never airborne again. Today, the Spruce Goose can be visited at the Evergreen Aviation Museum in McMinnville, Oregon. There it stands as the centerpiece of the museum, a wonder of innovation, aviation, and pride.