The Hughes H-4 Hercules, aka The Spruce Goose

Apple | Spotify | Amazon | iHeart Radio | Player.FM | TuneIn
Castbox | Podurama | Podcast Republic | RSS | Patreon

Podcast Transcript

During the height of the Second World War, American shipping to Europe was constantly being attacked by German U-boats. 

In an attempt to completely bypass German subs, aviation pioneer Howard Hughes began construction on what would be the world’s largest aircraft. 

A plane that was so large it could carry 750 passengers or two full-sized tanks across the Atlantic. 

Sadly, it was hampered by wartime rationing of metals and only flew in one memorable test flight.

Learn more about the Hughes H-4 Hercules, aka the Spruce Goose, on this episode of Everything Everywhere Daily.

In 1942 the American military had a big problem. 

They were shipping enormous amounts of supplies to Britain, but the supply ships were getting picked off by German U-boats. Known as the Battle of the Atlantic, it was the longest continuous military engagement of the war. 

The losses by the allies were staggering. From 1939 to 1945, between the British and the Americans, 3,500 merchant vessels and 175 warships were sunk, resulting in the deaths of 36,000 navy sailors and another 36,000 merchant marine sailors.

The Americans and British developed techniques for combating the German submarines, but ultimately they could only mitigate the problem. So long as the bulk of equipment and personnel being sent from America to Britain had to be sent by ship, it was vulnerable to U-boat attacks.

The ultimate solution to the problem would just be to bypass the sea entirely. 

The idea for creating an airplane that was large enough to transport cargo as a ship came from the shipbuilder Henry Kaiser. Kaiser was responsible for the construction of most of the Liberty ships which were built. 

Liberty Ships were low-cost, mass-produced cargo ships, all of a similar design, which were constructed at 18 shipyards around the United States. They were constructed at a rate of three every two days, and 2,710 of them were constructed between 1941 and 1945. 

Kaiser felt that a large airplane would solve the problem and help win the Battle of the Atlantic. However, he was a shipbuilder and knew nothing about airplanes. He took the idea to the owner of Hughes Aircraft, Howard Hughes. 

Hughes liked the idea as it would push the boundaries of aviation, which was something he was always in pursuit of. 

Together, Kaiser and Hughes jointly proposed the flying cargo ship to the United States government. The government approved the development of three aircraft over the next two years. 

The specification for the aircraft was that it could carry 150,000 pounds or 68,000 kilograms of cargo. This would be large enough to carry 750 soldiers or 2 Sherman tanks. The wingspan of the plane would be 320 ft 11 inches or 97.82 meters….the size of a football field. 

The aircraft was designated the HK-1, which reflected the fact that it was a joint project of Hughes and Kaiser. 

Other than wanting to build a really big airplane, they didn’t have any particular design in mind. 

One of the things that became obvious was that the plane would have to be a seaplane. There simply weren’t any airstrips large enough to support a plane of this size. It would also eliminate the need for landing gear, which would help reduce weight. 

They considered dual hull designs as well as various engine configurations.  The final design they settled on was a single massive hull design. 

The plane would have eight Pratt & Whitney R-4360 Wasp Major 28-cylinder air-cooled radial piston engines producing 3,000 horsepower each. It was the largest piston aircraft engine ever produced by Pratt & Whitney before they went into the production of jet engines. 

The engine was eventually adopted for use in aircraft such as the Boeing 377, Boeing B-50 Superfortress, and the Boeing C-97 Stratofreighter.

There was one major problem that they encountered. For an airplane of this size to work, it had to be extremely lightweight, as it was already going to be carrying such a heavy payload. 

The ideal material for its construction would have been aluminum. Aluminum, however, wasn’t as abundant during World War II as it is today. Aluminum was considered a strategic material by the US government, and its use was rationed. 

Without the ability to procure aluminum, they had to find a substitute. Something that was relatively lightweight and strong enough to build an aircraft out of. 

The solution which they landed on was a substance known as Duramold. 

Duramold was a type of plywood that used sheets or piles of wood, infused them with a resin, and then allow them to set in a mold. 

The use of Duramold was considered to be either on the cutting edge of technology or a joke because it used wood. 

Critics of the plane dubbed the Spruce Goose or the Flying Lumberyard.

In fact, there is almost no spruce used in the creation of the Spruce Goose. The wood is almost all birch and poplar. 

Henry Kaiser let Hughes take the lead on the project, given their experience in aircraft design. However, the use of a novel substance like Duramold and the perfectionism of Howard Hughes resulted in constant delays in the aircraft.

After two years, the HK-1 never met its delivery target, and Kaiser pulled out of the project. 

Howard Hughes, however, decided to continue on by himself. The plane was now renamed the Hughes H-4 Hercules. 

He renegotiated his contract with the government, this time only promising to deliver a single prototype aircraft. 

Work on the plane continued at the Hughes Aircraft facility in Los Angeles. However, the construction of the plane took much longer than anyone anticipated. 

No one had ever built an airplane of this size before, and no one had built a large aircraft out of Duramold before. Everything they did had to be figured out from scratch.

By the time the war ended in 1945, the plane still wasn’t complete. 

With the end of the war, the entire reason for building the plane disappeared. Once the danger of U-boat attacks went away, ships were much cheaper and more efficient for transporting goods. 

Nonetheless, Howard Hughes continued production of the plane. He had invested not only his money in the project but also his reputation. 

Eventually, the plane was ready for final assembly, but it was too large to be transported from Hughes’s facility in Los Angeles to the port of Long Beach. 

The plane had to be moved in four different parts. The fuselage, both wings, and the tail section. 

A specially designed hanger was created on the shore for final assembly.

However, before testing of the aircraft was to begin, in August 1947, Howard Hughes was called to testify before a Senate committee investigating war profiteering and wasteful spending. 

Hughes was called in as a high-profile witness, which attracted a great deal of media attention. 

Many Senators thought that the committee hearings would embarrass and discredit Hughes, but he managed to turn it into a media triumph. 

When asked where the $23 million dollars the government invested into the plane went, he pointed out that every aviation company had development contracts for undelivered aircraft. Moreover, he pointed out that he had personally spent more money on the development of the Hercules than the government did. 

In perhaps his most famous sound bit from the hearings, he said, 

The Hercules was a monumental undertaking. It is the largest aircraft ever built. It is over five stories tall, with a wingspan longer than a football field. That’s more than a city block. Now, I put the sweat of my life into this thing. I have my reputation all rolled up in it, and I have stated several times that if it’s a failure, I’ll probably leave this country and never come back. And I mean it.

In November 1947, Hughes returned to Los Angeles to conduct the first taxi runs of the Hercules. The purpose of the tests was literally just to take the plane out for the first time under its own power. It would power up and head out on the water in a mock take-off, and that was it. 

On November 2, the tests began with Howard Hughes himself as the pilot.  The plane had 36 people in total on board, including Hughes, the co-pilot, mechanics, media, and several representatives from the aviation industry. 

There were two taxiing attempts where the media was able to take photos of the plane in action. Most of the media in attendance left after the second taxiing attempt to go and file their stories. 

However, during the third attempt, Hughes made the unexpected decision to pull up and make the giant plane airborne. 

It wasn’t much of a flight, but Hercules did fly. It reached a peak altitude of only 70 feet or 21 meters. It reached a speed of 135 miles per hour, or (217 kilometers per hour, and flew for 26 seconds for a distance of one mile. 

It was the only time the H-4 Hercules ever flew. 

The reason why Hughes made the decision to make the plane fly was to silence his critics. It was hard to say that he wasted government when he proved that the plane could fly. 

The plane was taken out of its hanger a few more times for another taxi demonstration, but that was it. 

As I mentioned before, the H-4 Hercules was now obsolete. A huge cargo-carrying airplane had no use now that the war was over. 

However, Howard Huges had a special place in his heart for the Hercules. He paid for a crew of 300 people to maintain the aircraft in flying condition for 15 years. An enormous expense for something that had no future and no purpose. 

The crew was eventually reduced to 50 people in 1962 and then was totally abandoned after Hughes’s death in 1976. 

After Hughes died, there was debate about what to do with Hercules. The US Government originally made a claim on the airplane with the intent of putting one of the wings on display at the Smithsonian Air and Space Museum. 

In 1980, the plane was purchased by the Aero Club of Southern California. The plane was moved to a specially built geodesic dome alongside the Queen Mary cruise ship.

The site was eventually purchased by the Walt Disney Corporation who didn’t want to have the plane as an attraction anymore. In 1993, the Spruce Goose was sold to the Evergreen Aviation & Space Museum in McMinnville, Oregon, where it sits today. 

One question which has lingered about the Hercules is if it could have actually flown for real and have fulfilled its mission. Several aerospace engineers have analyzed the plane and, with modern computer simulations, have determined that it absolutely could have flown. 

…although it would have been even better if it could have used metal instead of wood. 

After the brief flight of the Spruce Goose, there were many large airplanes that were built. The B-52 bomber, the Boeing 747, the Airbus A-380, and many others approached the size and wingspan of the Hercules. However, nothing was ever quite the same same size. 

That was until 2017 when the Stratolaunch flew for the first time. The Stratolaunch was a dual-hulled plane built to launch satellites into space. It was the first airplane that could unequivocally be said to be larger than the Spruce Goose. 

By pretty much any measure, the H-4 Hercules was a failure. It never managed to transport anything to Europe to assist in the war effort, and it was a colossal waste of money. However, as failures go, it was a pretty incredible one. One that has captured the fascination of aviation enthusiasts and the general public for almost 80 years. 

The Executive Producer of Everything Everywhere Daily is Charles Daniel.

The associate producers are Thor Thomsen and Peter Bennett.

I have some more boostagrams to share with you today. Heatherfaye sends 500 sats from the Moon Rocks episode on the Fountain app and says. 

Things that are invaluable : moon rocks, and Everything Everywhere Daily. Also, shout out to Charles Daniel and Peter Bennet, who I am assuming are equally as awesome as Thor.

Thanks, HeatherFaey. Indeed all the show producers, past and present, are esteemed and honored in the eyes of the host. 

Flashgordon sends 5000 sats from the Fountain app and says 

Grest show, didnt know you accepted sats, here’s mine so far from the Fountain app.

Thanks, Flash! I most certainly do accept sats, and the Fountain app is one of the easiest ways to send feedback on individual episodes. 

Remember, if you leave a review or send me a boostagram, you too can have it read on the show.