[Military Sub-Plane] By Friedrich Lau
Speaking of the An-225, you must have heard that it is the largest aircraft in flight in the world today, and will also quote its destruction and sigh, but you must not know that the An-225 is not the largest aircraft in the world, but the H-4 "Lux" large seaplane developed by the United States during World War II, this full-body wooden structure of the giant beast is more than five stories high, the wingspan is longer than the An-225, comparable to a football field, can carry more than 700 people at a time. But the plane was eventually shelved after only one test flight, and was called the embodiment of romance and dreams rather than the crystallization of aviation technology. Here's how the plane went through its bumpy life.
H-4 during test flights in Long Beach, California
After the outbreak of World War II, as the United States entered the war and faced a shortage of metals in the early stages of the war, the Allies began to think about how to transport large numbers of people, equipment and goods to Britain without being sunk by German U boats cruising in the Atlantic. In response to this problem, James Vernon Martin, an American pilot who had invented automatic stabilizers and retractable landing gear, proposed a seaplane program known as the "ocean plane" to solve the problem, but few people were interested in it at the time.
Subsequently, British Prime Minister Winston Churchill showed interest when he heard about the plan, but because the British side was unwilling to allocate research funds, Churchill informed US President Roosevelt of the plan, and then Roosevelt proposed to the industrialist Henry John Kaiser to start the development work, and Caesar remembered Howard. Robard. Hughes, in his 20s, was already a well-known Hollywood producer, engineer, inventor and pilot, and his aircraft had set several world records. Despite his inventive talents, Hughes never received formal engineering training and instead taught himself after dropping out of college, but he loved the challenge so much that after some consideration, he agreed to work with Caesar to make the seaplane an ideal into a reality. At this point, for some time at the beginning of the project, Caesar's expertise in shipbuilding and Hughes's experience in designing experimental aircraft were seen as the perfect match.
▲ Howard. Robard. Matthews
But the U.S. military did not facilitate much of their research efforts, because the need to meet the needs of war, so the metal was prioritized for the construction of conventional aircraft, tanks, ships, and various types of weapons, so Hughes's team could not use other metals such as aluminum during the design process. In addition, the aircraft is required to carry at least 750 people or tanks and other heavy equipment. As a result, Hughes began to consider using readily available wood for fuselage structures, although he considered it the least desirable material for building large aircraft.
Industrially made metal plates with uniform weight, consistent properties and high tensile strength are important factors to consider in aircraft design. The performance of wood depends entirely on the climate in which the tree grows and the felling season, etc., and the uncertainty is high. So while it's possible to make small and practical aircraft out of wood, designing an aircraft that meets such heavyweight requirements is a different story, meaning that every piece of wood on the fuselage needs to be carefully considered.
▲ H-4 huge cargo hold
After consulting with the wood experts, the Hughes team decided to adopt birch and spruce. The production of the plates is carried out by Rodis Manufacturing, which is known for specializing in the manufacture of a plywood and resin product known as Duramold. In November 1942, the U.S. government provided $18 million ($27,467,441,193.55) to develop and build three of these aircraft. The new aircraft will be named HK-1 ("H" stands for Hughes, "K" stands for Caesar) on board and work quickly begins.
▲The size of the H-4 and the Douglas DC-3 transport aircraft
To meet the military's requirements, the HK-1 must have a wingspan of 320 feet (97.5 m) and a wing area of 11,430 square feet (1,061.9 m2). The fuselage must be 218 ft 6 in (66.5 m) long, 80 ft (24.4 m) high in the tail, and 113 ft 6 in (34.5 m) wide. To accommodate 165,000 cubic feet (4,672.3 cubic meters) of cargo, a fuselage 30 feet 6 inches (9.2 m) high and 24 ft 5 inches (7.3 m) wide was also required.
To make it fly smoothly, the plane needed eight Pratt-Whitney R-4360 Wasp piston engines, each providing 3,000 horsepower. Eight 4-blade propellers with a diameter of 17 feet 2 inches (5.2 m) produced by Hamilton Standard were also required.
▲P-Hui R-4360 engine
Finally, when the design was complete, the entire aircraft weighed 400,000 pounds (181.4 tons) and had a maximum payload of 130,000 pounds (59 tons). The aircraft's cruising speed is estimated at 175 mph (282 km)/h (maximum 218 mph) and can fly 3,000 miles (4,828 km) at an altitude of 20,900 feet (6,370 m), a range sufficient to reach the UK, avoiding the problem of the transport fleet taking the sea route to encounter U-boats.
But just as the design work was steadily advancing, two problems lay in front of us. The first problem was that the U.S. government's slow pace of providing the necessary materials and funding for the project sparked Caesar's displeasure. The second problem stems from Hughes's perfectionism, which constantly revises every detail, such as the control panel and the position of the seat. The two problems superimposed, eventually causing Caesar to leave the R&D team, and Hughes changed the aircraft's code name to H-4 Lux, or spruce goose.
▲The cockpit scene inside the H-4 aircraft
Due to Hughes's demand for details, the aircraft design was slow, and under the constant urging of the U.S. government, construction work finally began in 1944. By this time, the United States had emerged from the Great Depression, industry was booming, and there was no longer a shortage of metal products. At this time, the German U-boats could no longer pose a greater threat to the Allied fleet.
In 1945, the U.S. government considered canceling the project, but Hughes continued to use his influence to lobby and try to keep an airplane in production. So by the end of World War II, there was still an airplane still under construction. But the top brass couldn't stand it because they had invested nearly $40 million in the project (about $44,004,66511.63 today) and didn't come in handy. In August 1947, Republican Senate Ralph Owen Brewster formed a Senate War Inquiry Committee to investigate Hughes' "misappropriation of government funds."
Ralph Owen Brewster.
Although Hughes was subsequently acquitted, he had to prove that the aircraft could be put into service or it would be considered a breach of contract. Because the plane was built in Playa Vista, Los Angeles, the massive fuselage needed to be transported to Long Beach in three parts for testing. After assembling at the destination, Hughes personally piloted the aircraft for a brief test flight on November 2, 1947. Subsequently, the aircraft successfully flew more than 1600 meters at a horizontal flight attitude of 24 meters above the water surface. And even if the test flight is successful, the aircraft no longer has to adapt to the needs of war, and at this point, the first flight of the world's largest aircraft has become a masterpiece.
Currently, the plane is housed at the Evergreen Aviation Museum in McMinnville, Oregon, for human viewing.
▲ H-4 preserved by the Evergreen Aviation Museum