Hughes H-4 / HFB-1 Hercules


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Hughes H-4 / HFB-1 Hercules

The truly massive Hughes H-4 Hercules flying boat was conceived by reclusive millionaire entrepreneur Howard Hughes in 1942 as a means of delivering massive quantities of men and materiel to various war zones, hence avoiding the submarine menace that presented a constant threat to merchant ships.

On 2 November 1947, the Hercules - nicknamed the 'Spruce Goose' because of its wooden construction, although the wood was mainly birch, not spruce - made a short flight of about a mile over Los Angeles roadstead in front of an excited crowd estimated at 50,000 people, rising 21m off the water and reaching a speed of 129km/h. Yet by 1947 the aircraft no longer had any strategic value, and it never flew again. Today, it is on permanent display at the Evergreen Air Venture Museum, McMinnville, Portland, Oregon. It is still the largest aircraft in the world (only by its wingspan).


The four inner propellers had reverse-pitch capability, allowing the H-4 to back up and manoeuvre easily on water. Each propeller was 5.2m in diameter.

The 'Spruce Goose' was the only Allied aircraft designed during the war able to carry main battle tanks. In theory a fleet of H-4s could have ferried armies to Europe, saving time and avoiding the risk from submarines.

The main structure was not spruce, but laminated birch. Attempts to use a resin-impregnated plywood material called Duramold were unsuccessful.

Hughes H-4 / HFB-1 "Hercules" on YOUTUBE

Hughes H-4 / HFB-1 Hercules

 ENGINE8 x Pratt & Whitney R4360-4A, 2236kW
  Wingspan97.5 m320 ft 11 in
  Length66.6 m219 ft 6 in
  Height24.1 m79 ft 1 in
  Wing area1061.8 m211429.11 sq ft
  Max. speed378 km/h235 mph
  Cruise speed225 km/h140 mph
  Ceiling6400 m21000 ft
  Range2535 km1575 miles

Hughes H-4 / HFB-1 HerculesA three-view drawing (1276 x 1268)

Comments1-20 21-40
Howard, e-mail, 14.08.2023 02:58

Doing some serious analysis on the vertical stabilizer attachment to the
fuselage. There was talk of some flutter during its one and only flight. Based of attaching it to a round, narrow, tapering fuselage, I have serious concerns (even with the doublers added as strengthening the rear fuselage after the flight),the tail would have had extreme loads on it during the course of flight. I think this may have been the nail in the coffin for not flight testing it...shame, we'll never likely know.


Vahe David Demirjian, e-mail, 23.09.2022 03:48

This entry should be slightly updated because the H-4 Spruce Goose is no longer the biggest aircraft by wingspan, since the Scaled Composites Model 351 Stratolaunch flown in 2019 has a wingspan of 385 feet.


Harry Winsor, 03.06.2020 18:20

What a heap of american Shi-ite


Bruno, e-mail, 16.05.2023 Harry Winsor

this is a design master class


Willis Vanderberg, e-mail, 21.01.2018 04:17

Mr Loves statement about Mr Hughes releasing the R4360 engines to Boeing. The B29 was powered by the Wright Cyclone R3350 engines. The R4360 had limited usage. One was on the Martin P4M Mercator. It had two 4360s and two J33jet engines. It was also used in the Martin AM -1mauler. As far as I know that was the only single engine aircraft to use that huge engine.


Bill Krening, e-mail, 03.01.2015 06:36

While visiting Evergreen Museum I asked a Docent\\volunteer about what appears to be repair doubler's all around the empenage just forward of the tail fins,he put me in touch with another volunteer that evidently worked for Hughs on the HK-1. I was told that on the one and only flight that the empenage started showing day light from a crack opening up in the skin. The person assigned to that area with a radio keyed his mic and rather urgently shouted to "put it down the tails coming off"!! Of course they landed safely and evidently repaired /strengthened the the empenage with several external "doublers", as they are referred to in the aircraft industry. And no...I didn't feel a tug on my leg, he spent to much time with the technical aspects and was as sincere and helpful as all the volunteers. As secretive as Hughs was I'm not surprised that I cannot find anything in print on this....... Any help on this?


Dennison Love, e-mail, 22.05.2013 06:34

If Times Were Different.

Had everything gone as planed the HK-1 project would have saved the day for the Allies as the world's first flying Liberty Ship".

You had better make that fleets of flying "Liberty Ships", with well over 1,500 Flying boats being built, by 1947.

During the early part of the Battle of the Atlantic, the German's U-boat Fleet almost put the sea going, "Liberty Ships on the endangered species list.

It became apparent that the United States had to come up with a better method to deliver all of their war goods.

Howard Hughes & Henry Kaiser teamed up and the HK-1 was born; their goal was to build a fleet of Giant flying boats "Liberty Ships" named "Hercules".

Constructed from common materials these gigantic aircraft would be considered as expendable as gliders, with the Hercules prime job of delivering war supplied directly to where ever needed.

With the endurance to fly nonstop from the United States to any location on the surface of the Earth then return.

Well it didn't work out, Hughes designed the aircraft as a series of modules & it was Henry Kaiser job to have them built.

The problem was Henry Kaiser built them one module at a time and by the end of the war, Kaiser had not made all of the different modules necessary to build a single HK-1, and Millions of dollars were spent without producing any complete aircraft. Then the war was over, Henry Kaiser died of a heart attack leaving

Howard Hughes with the whole operation, all the plans & most of the modules with of four mock-up aircraft.

Hughes got himself caught up in a federal funding scandal.

The "Press" of the era quickly picked up on cost of the HK-1 program and noted the large number of zeros in the figure came up with the nick name "Spruce Goose" with the "00" for all the millions of dollars spent on the project.

Hughes put his reputation on the line, to make the "Spruce Goose" fly, so he took all the leftover parts and fourteen million of his own dollars to put the H-1 Hercules into the air.

The only spruce wood used on this aircraft was located in the navigators table, upon hearing the new nickname?

Spruce Goose" Hughes had the wooden table replaced with a metal on.

As you are aware Hughes only made one short flight, then put the largest airplane in the world in storage never to fly again.

After Howard Hughes death the aircraft was acquired by several different enterprises, its last move was to the Evergreen Museum, located in Oregon.

But if times were different, and Henry Kaiser had time to make all his modules, before the end of the Second World War, had lasted till January 1946, there would have been a first batch of 500 flyable HK-1 Hercules aircraft in operation, for the Invasion of Japan.

The first batch of 500 in 1946, and another 1000 if, the United States needed them in 1947.

What we now know about what would have happened during the invasion of Japan the first 500 HK-1s would have been used to deliver personal and equipment directly in to the Japanese contested beach heads, with empty returning Hercules being used to evacuate the wounded.

This model is built to show what the HK-1 would have looked like had times been different, and it had gone operational with all of the Allied Nations.

Their battle plan would have been to keep it out of harm's way by having an experienced crew that knew where the harm was & how to stay away from it.

So this small exhibit of 1 /200 scale aircraft are showing you the exact size difference between all the modern large transports note the size of the HK-1 next to the C-47 which was the main transport for most of the Allied Countries during the Second World War.

I installed a cargo door the same size as the C-47's in the port empennage of the HK-1. Notice its exact size next to all the other model aircraft.

Plans called for the Hercules to be crewed by experienced aircrews that would come from all the battlefronts around the world. Had the HK-1 gone into operation it would have had the largest flight crew ever used on an airplane.

Who knows the HK-1 going into operation might have given the WASP's Pilots a rebirth and their first overseas operations.

As we know from history we would have needed them in a very big way. Hughes's biggest problem just prior to the shutting down of the program was the loss of all of his engines to Boeing, to fix their B-29's, despite Hughes having the engine supplier under contract, and it took a direct order from "Hap Arnold" to get Howard to releases engines to Boeing.

General Arnold figured he could trade one un-built HK-1 for two B-29's. Just think of how the HK-1 could have changed the world, if its construction had started earlier, the Flying Tiger in China would have lasted a lot longer, with a squadron or two of HK-1?s flying all their much needed supplies, from the Indian Ocean directly to "Tiger Bases ...


Eugene A. Dumont, e-mail, 21.12.2012 16:00

I have some drawings that I have for long time. I am trying to build a model of said HK_1 or HK 4. I am making out alumenium pop cans. It has a 48 inch wing span.


Bill, e-mail, 06.12.2012 22:51

Disney bought the Queen Mary and HK1 as a center piece to a new amusement park that was being proposed in Long Beach. This was a because Anaheim was not coroporating with expansion. plans to Disneyland. Once Anaheim agreeded to expand the park, Disney abandoned the Long Beach plans and sold the QM and HK1 as part of the deal. All that remained was the Aquarium of the Pacific.


Greg Lugn, e-mail, 21.09.2012 21:56

Chris: While the H-1 /H-4 is an amazing engineering feat, trying to produce it in any quanity would be almost impossible. It would have to be reengineered to be made out of regular aircraft material. Wood varies in density & weight too much. That was one of the reasons construction took so long. They were constantly haveing to refigure wt & strength amts, etc. But, as the US Navy discovered in the late 40's, early 50's, the day of the huge flying boat was over.


fabio, e-mail, 03.03.2012 16:59

I remember perfectly to have seen a newscast when I was 16: I was so excited that I wrote down the information on a book about aircrafts, I still have it. On 28 February 1978 at the behest of the heirs of Hughes, the Spruce Goose was flown for a few minutes. The flight was crowned with success. The event was filmed by a television crew. Does anyone remember this? Unfortunately I can not find other useful information.


Graham H. Hughes, e-mail, 05.02.2012 22:53

In 1994 my wife and I visited Evergreen Aviation. We had travelled from Liverpool, England to stay with friends in British Colombia and also to dip into Washington and Oregon and find the HK1, which we knew had been relocated to McMinnville. Upon our arrival, we met a very pleasant chap who greeted us warmly and I said "I,ve come to see my uncle Howies aeroplane".He informed us that we could not go on to the plane because of the restoration work being done. This was a tremendous disappointment to me, but I did understand
the "Health and Safety" issues involved. We stayed at the site for a couple of hours enjoying their hospitality and looking around the collection of small aeroplanes,a couple of racing cars and a fabulous "cut-away" version of a Pratt and Whitney engine. We joined "Friends of the Museum", with family membership and bought HK1 T-shirts for our children.When we were leaving, we asked our host to take a photo of the two of us in front of the fuselage of the HK1 which was in a plastic hangar behind a wire fence. He put the camera to his eye, then lowered it and said these immortal words, "I think I can find the key to the gate in the wire fence" This he duly did and guided us onto the flight deck of the HK1. I sat in the very seat that Howard Hughes had sat in when he flew the HK1. I had done some private flying in the 1970,s but this was the aviation thrill of my lifetime. Mine host took a photo of us at the controls and I said "lets pretend that we are landing" and I drew back EIGHT throttle levers as my wife did the flaps.


3 times Jane, e-mail, 09.09.2011 01:42

We hear you Jane, We hear you Jane, We hear you Jane,


Bob Hartunian, e-mail, 26.08.2011 08:12

i worked for Mr. Hughes at Hughes Tool Co.-Aircraft Division in 1962-63 flight testing helicopters. The mechanics on the Flight Test line referred to Howard Hughes as Mr. Hughes, always. And the plane as the Flying Boat. Our senior mechanic was John Thomas who lectured me as a young kid engineer about Mr. Hughes and how you could walk inside the wing of the Flying Boat and service engines while in flight; an amazing plane.
I saw Mr. Hughes once when he flew into Culver City and fired a Marketing Director and his secretary for hanky panky. Hughes would not stand for it. He wore a fedora hat and piloted an old dirty looking Beech 18. He owned the place and could do as he wished. The mechanics loved him.


Jane, e-mail, 21.06.2011 18:47

When I worked for Hughes Aircraft Co.(1984-1989) it was always referred to as HFB-1 (Hughes Flying Boat-1). I've never heard it referred to as the H4 Hercules until the commercials for the museum on the radio.


Jane, e-mail, 21.06.2011 18:47

When I worked for Hughes Aircraft Co.(1984-1989) it was always referred to as HFB-1 (Hughes Flying Boat-1). I've never heard it referred to as the H4 Hercules until the commercials for the museum on the radio.


Jane, e-mail, 21.06.2011 18:46

When I worked for Hughes Aircraft Co.(1984-1989) it was always referred to as HFB-1 (Hughes Flying Boat-1). I've never heard it referred to as the H4 Hercules until the commercials for the museum on the radio.


Ron Sillett, e-mail, 18.04.2011 09:11

I'm a docent at the Evergreen Aviation Museum. The "Spruce Goose" is indeed made of wood. 95% Birch, 1% Spruce. The Spruce is in the keel & wing spar. Powered by eight P&W R4360 28 cylinder engines of 3000 HP each. It flew one time at a height of about 25 feet for less than a minute and less than a mile. Although it was kept flight-ready for the first 10 years, it was never flown again. It still has the longest wingspan of any plane ever built. It is truly an amazing feat of engineering.


Kadesh, 08.03.2011 00:38

I work at the Evergreen Aviation Museum as a volunteer on weekends, they bought the H-4 for just a dollar. Seriously, despite shipping costs, all Disney got out of it was a dollar.


James Kadas, e-mail, 31.01.2011 04:43

Disney was the owner of the Spruce Goose before Evergreen Aviation in McMinnville Oregon got it. Disney didn't want it anymore and was about to break it up into eight pieces and send it to different museums. It was put up for Bid and Evergreen Aviation and Space Museum put in the winning bid.


Elliott Boone, e-mail, 01.01.2011 00:59

The HK-1 (aka the Spruce Goose)was relocated from the Pier E hangar at the Port of Long Beach to the Queen Mary in 1984 because the lease with its Owner, Summa Corporation, sucessor to Hughes Tool Co., had long since expired and the site had reverted to a month to month rental. The Port, seeking higher revenue for the site solicited offers for use as a petro terminal, which was eventually leased to British Petorleum (BP) to import Alaskan Crude. I was the Project Manager for the lift and transport for the 1984 relocation to the Queen and again in 1994 from the Queen to its present site in McMinnville


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