Today in Microsoft Flight Simulator, I’ll be attempting to fly Howard Hughes’ giant H-4 Hercules. Constructed almost entirely out of wood, it was for a long time the largest airplane ever built, and flew only once. Why was it built? Read on …

In an earlier post, I described Howard Hughes’ early career, and the H-1 Racer he built in 1935 to set new world speed records. As I also mentioned, he tried but failed to sell the H-1 to the U.S. Army as a high-performance fighter plane.

Even after World War II began, and the U.S. aviation industry was booming with wartime orders, Hughes Aircraft failed to secure any military contracts. His proposed D-2 fighter, which looked much like a P-38, was an expensive flop.

Since 1939, Hughes owned a controlling stake in Transcontinental and Western Airlines (TWA), and played an important role in encouraging development of the Lockheed Constellation. But Hughes Aircraft itself seemed to be losing out.

The brainstorm for a gigantic cargo plane didn’t originally come from Hughes, but from construction tycoon Henry Kaiser.

At the start of World War II, the U.S. was losing huge numbers of irreplaceable cargo ships to German U-boats, threatening the ability of the U.S. to keep Britain fighting and eventually turn the tide in Europe.

Kaiser proposed to mass-produce “Liberty Ships” faster than the Germans could sink them. Initially ridiculed due to his lack of any experience in shipbuilding, his proved skeptics wrong, building over 2,700 ships at an average pace of 39 days per ship.

Still, to avoid U-boats altogether, Kaiser speculated that a large cargo airplane or “flying boat” could be developed to carry supplies across the ocean, entirely beyond their reach.

Kaiser knew nothing about designing planes, but he heard that Hughes did. He approached Hughes with a proposal for a partnership: you design the giant planes, and I will build them. Hughes initially thought the idea was “crazy”, but soon realized that it could be his shot.

So, in the fall of 1942, began a saga that was to outlast the war the giant plane was intended to help win.

Part of the problem was that Hughes excelled at producing daring new prototypes based on ambitious ideas. Sometimes they worked; sometimes they didn’t. But he had never successfully produced more than a single, custom-built airplane in his career.

The plane would need to be capable of carrying 150,000 pounds (68,000 kg), including either 750 fully equipped troops or two 30-ton M4 Sherman tanks.

Because wartime supplies of aluminum were committed to existing planes, engineers decided that the HK-1 (originally named after Hughes and Kaiser) would have to be constructed mainly out of wood.

They would have to be “flying boats” operating from water, because no airports would be large enough to handle them.

The contract called for three prototype planes to be built in two years’ time (by 1944) for $18 million (about $332 million today). But delays designing and constructing even the first gigantic airplane began to pile up.

The engineers found working with wood on such a scale presented unprecedented difficulties. Multiple layers of birch plywood had to be bonded with special waterproof resins in a process dubbed “Duramold” to form a kind of strong composite.

Due to wartime restrictions, Hughes had trouble hiring workers, men or women, with experience in aircraft manufacturing. Many of the people he ended up hiring were carpenters and cabinetmakers.

As the tide of the war turned, and the U-boat menace subsided, President Roosevelt nearly cancelled the project. Eventually, the contract was reduced to just one airplane for the same price tag, $18 million.

Even then, Hughes knew he would have to spend millions more (ultimately $7 million) of his own money to finish just one plane. He stuck with it, even as Henry Kaiser lost interest and dropped out. Critics called the plane the “Spruce Goose” or “Flying Lumberyard”.

The only piece of good news was that the U.S. Army was interesting in buying an updated version of the D-2 fighter, called the XF-11, as a photo reconnaissance aircraft. It ordered 100 from Hughes for $43 million.

Finally, in June of 1946, the H-4 Hercules (as it was now called) was moved in pieces from Hughes’ factory in Culver City to Long Beach Harbor for assembly.

Thousands of people came out to watch as the massive wings and fuselage were carried 28 miles by flatbed truck, at a cost of $80,000 ($1.2 million today).

They were brought to a specially-made drydock at Long Beach Harbor, where the plane was assembled in place.

Under the strain of managing two major projects, Hughes was starting to behave even more oddly than normal. Then disaster struck. On July 7, 1946, taking the XF-11 prototype on its first test flight, Hughes lost control and crashed in a residential part of Beverly Hills.

This scene in the 2004 Martin Scorsese film “The Aviator”, starring Leonardo DiCaprio as Howard Hughes, depicts the XF-11 crash:

Hughes was severely injured, and nearly killed. Many believe his already fragile mental health also took a tremendous blow.

He barely recovered when he came under harsh public scrutiny. The U.S. Senate, frustrated that both the H-4 Hercules and the XF-11 had yet to materialize, demanded he publicly testify in response to charges of being a war profiteer, scamming the U.S. government out of millions.

The hearings were heated. Congressmen demanded to know why the Hercules hadn’t even flown yet. Hughes accused Sen. Brewster of personally targeting him on behalf of PanAm CEO Juan Trippe, to prevent TWA from competing with PanAm for international routes.

Stung by the accusations, Hughes returned to Long Beach with a plan to exonerate himself. And this is where we join him – and the Hercules – on November 1, 1947, the day the giant plane was first launched from its drydock and presented to the press and the public.

It was, at the time, the largest plane ever built. The wingspan of the completed Hercules was 320 feet 11 inches, longer than a football field – or the Statue of Liberty on its pedestal, lying sideways.

The plane was 218 feet 8 inches long, roughly the same as a Boeing 747. The massive tail rose to 79 feet 4 inches, and by itself is the height of a 5-story building.

This illustration shows how the H-4 Hercules compares to some of the world’s other largest aircraft which were built later:

Keep in mind, though, that none of them even comes close to the size of a Zeppelin airship.

The Hercules was powered by eight Pratt & Whitney Wasp Major engines, the same as the XF-11, four on each wing. With 28 air-cooled cylinders each, they were the largest radial piston engines ever built, and produced an astounding 3,000 horsepower each.

The propellers, with adjustable pitch for constant speed, were 17 feet 2 inches in diameter. Each engine required 32 gallons of oil to keep it working properly.

The model in MSFS doesn’t show the cargo bay, so here is my own photo of it, taken a few years ago at the Evergreen Museum in McMinnville, Oregon, where the Hercules is on display. The first flight of the Wright Flyer, in 1903, could have fit entirely within its confines.

The beach balls at the lower right of the photo were discovered in the wing pontoons when the Hercules was moved and underwent restoration in 1993. They had been placed inside them as a backup, in case the pontoons themselves ever sprang a leak.

The cargo compartment would have been loaded through a large clamshell door at the nose of the plane, but since this was just a prototype, the doors were never installed.

Here’s a photo I took inside the plane, towards the nose. The metal stairway on the right leads up to the cockpit and crew cabin.

About 25 feet above the water, the cockpit offers a commanding view. That’s about the same height as a 747 flight deck, similar to the windows on the third floor of a building.

The H-4 Hercules was the first plane designed with a hydraulically-assisted steering system, capable of multiplying the pilot’s strength 200 times. This has since become commonplace in large airliners.

The instrument panel is fairly straightforward, with flaps and fuel indicators on the left, a vertical speed and airspeed indicator, heading indicator, attitude indicator, and altimeter (far right) along with a radio navigation aid.

To the left of the yoke is a crank for setting elevator trim, and the rudder pedals are at their usual place on the floor.

To Hughes’ left is a radio with a phone handset. Not pictured here was a big pipe that directed specially filtered air at his face while flying, to alleviate his constant, paranoid concern about germs.

Between the pilot and co-pilot seats are the throttles and engine gauges. Each of the four levers on each side controls two engines. There’s also levers for flaps and hydraulics, as well as an autopilot system.

While the co-pilot can fly the plane, his main job is to assist in operating its various systems. David Grant, a 30-year-old hydraulics engineer who sat in the chair beside Hughes, didn’t even have a pilot’s license.

Looking back from the pilot’s seat, you can see the station for the flight engineer, and beyond it the seating for the gaggle of journalists Hughes invited onto the Hercules the day after its official launch, November 2.

The flight engineer has panels for monitoring each of the eight engines in detail (left) and the flow of oil and fuel to each (middle). The right-hand panel controls the electricity and lights, alerts the engineer to fires, and starts the engines.

Directly behind the pilot, and across from the flight engineer, is a station for the navigator and radio operator. If you look closely, you can also see Howard Hughes’ hat.

Howard Hughes was a big coffee drinker, so the flight deck includes a coffee machine for everyone to enjoy.

At the back of the cabin are two APUs (Auxiliary Power Units), Franklin engines used to generate the airplane’s electrical power as well as start the engines. The ladder to their right leads up to an observation station the crew can access either in flight or while docking.

This metal tank here contains an extra reservoir of 189 gallons of oil, which can be directed by the flight engineer to any of the engines as needed. The little door behind it gives engineers access to the interior of the gigantic wing.

Here’s a perspective of the engine flight deck, standing next to the APUs (right) at the very back. The compartment takes up the entire front half of the plane, from the wings forward.

Here is some newsreel of Howard Hughes in the cockpit of the H-4 Hercules:

Let’s get the eight engines started, two at a time.

Each engine consumes over 100 gallons of fuel per hour at cruise speed. To supply that, the Hercules has 14 fuel tanks in its belly (under the cargo compartment) holding 1,000 gallons each.

On November 2, with journalists on board, Hughes took the H-4 Hercules out for what he said would be a series of taxi runs, to test the plane out. No one expected it to fly.

The big plane cut smoothly through the waters off Long Beach, reaching 90 mph. After two taxi runs, he let all but one reporter (Jim McNamara, from a Los Angeles radio station) off in a boat.

Then, with the reporters still watching, Hughes turned the Hercules into a brisk wind and began what was to be his third and last taxi run.

A gasp and a cheer from the onlookers when up when the airplane lifted off the water, a few feet into the air, at a speed of 135 mph. The Spruce Goose was flying.

The flight lasted 26 seconds, covered about a mile, and rose just 70 feet above the water. Rather than risk trying to land the plane in the choppier waters farther offshore, Hughes soon brought it in for a landing.

Barely airborne, it was the one and only flight the H-4 Hercules would ever make. But it was enough to serve Hughes’ immediate purpose: undercutting his critics. Now that the plane had flown, the hostile hearings in Washington DC lost steam and soon were adjourned.

Here’s a newsreel from the time, including footage of the actual flight:

Howard Hughes and the Spruce Goose (a nickname he absolutely hated) on the cover of TIME Magazine, July 19, 1948. “Money + brains = fun (sometimes)”.

At this point, under the contract, Hughes should have delivered the Hercules to the government. But guessing they would almost certainly end up scrapping it, he exercised an option to lease it back.

For the next three decades, until his death in 1976, Hughes kept the Hercules in a climate-controlled hangar in Long Beach, hidden from public view, maintained by a team of 300 workers tasked with keeping it in flying condition.

Once a dashing playboy, Hughes increasingly drew back, becoming a kind of ultra-wealthy hermit. Stories of his odd behavior abounded. When he died – without a recognized will – he left an estate estimated at $2.5 billion.

After his death, the Hercules went on display beside the ocean liner Queen Mary in Long Beach. In 1993, it was moved to the Evergreen Museum in Oregon, where it is on display today.

The hangar in Culver City where the Hercules was built was later converted to sound stages for movie production. “Titanic” was partly filmed there. More recently, it was converted to office and event space for Google.

But . . . what if Hughes had tried again. Could it have REALLY flown, as intended? The sim isn’t a reliable test, but I couldn’t resist giving it a try.

The H-4 Hercules weighed 250,000 lbs empty, 400,000 lbs (200 tons) fully loaded. When it rose to 70 feet in 1947, that was still within ground effect, giving it additional lift.

Nevertheless, I was able to gently coax it off the water and into the air.

The “Spruce Goose” is often portrayed as the fanciful dream of a mad man, like Don Quixote tilting at windmills. The world’s largest plane, made of wood, built for no good reason.

In fact, as its story makes clear, it had a very good reason – even if the resources available didn’t allow Hughes to achieve it within the relevant timeframe.

The H-4 Hercules was designed to have a range of 3,000 miles, enough to fly from Los Angeles to New York, from San Francisco to Honolulu, or across the Atlanta from Halifax to London.

At a designed cruising speed of 250 mph, it could have covered that distance in 12 hours, compared to 4-5 days for the fastest ships.

A fleet of them could potentially deploy a U.S. military force anywhere around the world in a matter of days, safe from U-boats and other threats.

It’s the same vision that ultimately gave birth to modern-day airlift giants like the C-5 Galaxy, capable of carrying 281,000 lbs to a range of 5,500 miles, at a speed of 532 mph. It even looks a bit like the Hercules.

Or the Antonov An-225, another one-of-a-kind airplane that nearly matched the Hercules in wingspan. It reigned as the world’s biggest plane, in weight, before it was destroyed during Putin’s invasion of Ukraine. I’ll be doing a thread on the An-225 soon.

In fact, the Hercules retained its lead in wingspan all the way until 2019, when Scaled Composites’ Stratolaunch took to the air to launch vehicles into Space. With a wingspan of 385 feet, the Stratolaunch follows in the Spruce Goose’s footsteps, being made from composites rather than metal.

It’s time to begin my descent to land, from the flight that never took place.

Out my side window is the Port of Long Beach, where the Hercules was built, and later hidden away for many years.

The white dome straight ahead, next to the Queen Mary, is where the Spruce Goose was on display from Hughes’ death to 1993, when it moved to Oregon.

When Hughes first flew the Hercules, his first instinct was to cut the power to descend. He had to be reminded by the hydraulics engineer in the co-pilot’s seat that without engine power, the hydraulic controls would no longer work.

So I’m going to try not to make that mistake, and still come in slow enough for a safe water landing.

Howard Hughes once said, “I want to be remembered for only one thing: my contribution to aviation.”

He is also reported to have said, “Do the impossible, because almost everyone has told me my ideas are merely fantasies.” I hope you’ve enjoyed the story of the impossible airplane he built, the H-4 Hercules.

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