This summer, visitors had a unique opportunity to see the transformation of American commercial aviation on the floor of the Mary Engen Restoration Hangar at our Steven F. Udvar-Hazy Center. There, resting side-by-side in chronological order, were the three airliners that transformed the U.S. airline industry, now removed temporarily from our flagship building on the National Mall to the Udvar-Hazy Center for conservation work before they are returned to exhibit in a revamped America by Air hall in 2022 as part of our project to transform the National Air and Space Museum in DC.

The Ford 5-AT Tri-Motor, the Boeing 247-D, and the Douglas DC-3 – three of the most important airliners in history – had been on display in the Museum since the building opened in 1976. Each is significant in its own right, but together they tell a crucial story of how and when American civil aviation quickly came of age in the 1920s and 1930s.

Ford 5-AT Tri-Motor

The Ford 5-AT Tri-Motor was automobile entrepreneur Henry Ford’s one and only foray into aviation. Based on the ideas of William Stout, the Ford Motor Company built a safe and reliable aircraft using the high-wing tri-motor layout of the popular Fokker F.VII-3m series of Dutch airliners of the 1920s and the all-metal corrugated aluminum alloy construction pioneered by Hugo Junkers in Germany during and after the First World War. Though a derivative design, the all-metal Ford Tri-Motor gained immediate acceptance because of its rugged construction and the inherent safety of its three engines. Henry Ford’s reputation for building reliable and affordable automobiles was instrumental in convincing a skeptical traveling public that an aircraft that bore his name was also reliable and, more importantly, safe.

The first Ford 4-AT took to the sky in 1926, powered by a trio of Wright J-5C engines, similar to the engine that powered Charles Lindbergh across the Atlantic in his Ryan NYP Spirit of St. Louisthe following year. In 1928, the more powerful 5-AT version entered service fitted with three Pratt & Whitney Wasp engines. Either version could carry up to 14 passengers in relative comfort for its day. There was room to move around and the seats were comfortable, whether they were wicker or aluminum, although headroom was limited when walking under the wing, which intruded into the cabin. Air conditioning was simple: if it got too hot, a passenger could simply open a window, believe it or not. Noise, however, was a constant problem. At take-off, the cacophony from the three engines could rise to deafening levels: 120 decibels – louder than the front row seat at a modern rock concert. Airlines would issue small packages containing cotton to plug passengers’ ears and chewing gum to help keep the ear canals open and stomachs calm during the frequently bumpy flights.

The Tri-Motor was safe and trustworthy, but it was also slow. Half in jest, the Ford was described as having a take-off speed of 100 miles per hour, a cruise speed of 100 miles per hour, and a landing speed of 100 miles per hour. An exaggeration, but not much of one. For commercial aviation to succeed, a new generation of faster, more efficient airliners was required to make air travel convenient and affordable.

Boeing 247

On February 19, 1931, Postmaster General Walter Folger Brown summoned the heads of the major airlines to a conference in today’s Old Post Office Building in Washington, DC. These large carriers were dependent upon lucrative air mail contracts for their survival, and the Postmaster General, who controlled those contracts, was not happy. Smaller, less reliable airlines were flying passengers in faster single-engine aircraft such as the Lockheed Vega and claiming that they could carry the mail cheaper than the current air mail contractors. The Vega could cruise at 150 miles per hour, fifty percent faster than the reliable Ford. Brown was embarrassed and facing pressure from these small airlines who wanted to upset his plan for a rational network of air routes serving the nation. 

At the meeting, Brown demanded that the airlines acquire newer, faster aircraft that combined the speed of a Vega with the dependability of multiple engines. At that time, the major airlines and the aircraft and engine manufacturers were joined into four large holding companies. The largest, the United Aircraft and Transport Corporation, included United Air Lines, Boeing, Pratt & Whitney, and a host of other aviation enterprises in a huge vertically integrated holding company. Boeing president Phillip Johnson, who was also president of United Air Lines, attended the contentious meeting and got the message. Immediately on his return to Seattle, he ordered the development of a new airliner to fulfill the Postmaster General’s requirement. The following month, this effort received an additional impetus when a Fokker F-10 trimotor of TWA (then Transcontinental and Western Air, laterTrans World Airlines) crashed, killing all on board including famed Notre Dame football coach Knute Rockne. The subsequent investigation revealed serious flaws in the construction of that aircraft’s wooden wing, which quickly hastened the demise of wooden commercial aircraft designs.

Although Boeing resided in Seattle in order to take advantage of the magnificent forests of spruce in the Pacific Northwest, it had also gained a great deal of experience working with all-metal aluminum alloy designs, particularly their single-engine Monomails and their B-9 bomber for the U.S. Air Corps. At this time, the aircraft industry was undergoing a revolution as new, more powerful air-cooled engines, such as the J-5C and the Wasp, made more practical the use of heavier but more durable all-metal construction with cantilevered lower drag wings and retractable landing gear. These advances enabled the B-9 to fly as fast as contemporary fighters yet carry a significant bombload. Johnson ordered Boeing to use those new technologies to produce a new airliner, the Boeing 247.

In February 1933, the first Boeing 247 took to the sky. Within four months it was revolutionizing air travel. When production versions were fitted with the first adjustable pitch propellers, the aircraft exhibited outstanding performance carrying its 10 passengers at a cruising speed of more than 160 miles per hour – 60 percent faster than the Ford Tri-Motors it was replacing. Yet it did so with one less engine and 20 percent less horsepower. 

Quickly the 247 came to dominate air travel. But as fast as this, the world’s first modern airliner, commanded the industry, it lost its advantage to an even better design.

Douglas DC-3

Boeing built the first 59 247s exclusively for its United Air Lines compatriot. Despite, William Boeing’s suggestion to sell the 247 to other airlines while building them for United, Johnson decided to give United the monopoly until that airline had all of the new aircraft it needed for its transcontinental route from New York to San Francisco. Only then would Boeing sell to its competitors. Jack Frye, vice president of TWA, realized that his airline could not wait that long if it wanted to maintain its own transcontinental route from New to Los Angeles.

In 1932, Frye sent a letter to the other aircraft manufacturers asking for a modern tri-motor aircraft to compete with the 247. Douglas Aircraft responded with a twin-engine design. Douglas was not dominated by any of the holding companies and was free to find the parts it needed from any source. At that time, Wright Aeronautical had developed its new Cyclone 9 radial engine that produced 700 horsepower, 150 more than the Wasps on the Boeing. This enabled Douglas to recommend a twin-engine design that could outperform any airliner in the sky.

Five months after the 247 first flew, the new Douglas DC-1 completed its maiden flight. With significant input from TWA’s technical advisor Charles Lindbergh, the DC-1 had sufficient power to take off and climb on one engine from the airport in Albuquerque, New Mexico,  highest on TWA’s transcontinental route. This clearly demonstrated the power and safety of the new machine. Tests revealed the need to stretch the aircraft to improve lateral stability so, in May 1934, the new DC-2 entered service.

The DC-2 carried 14 passengers in great comfort. The fuselage was significantly larger than the 10-passenger Boeing 247 and did not have its wing spars intruding into the cabin. Its cruising speed was an impressive 190 miles per hour, and it could cross the United States in 13 hours— six hours less than the 247 and two hours less than the improved 247-D. Immediately, the DC-2 became the airline of choice for the traveling public.

Douglas sold almost 200 DC-2s. One customer, American Airlines, wanted a sleeper version of the DC-2 to replace its large Curtiss Condor biplanes on its own southern transcontinental route. Douglas agreed, provided American would purchase 20 of the new aircraft, to which American Airlines president C.R. Smith agreed. The resulting aircraft was much more than a simple conversion. In order to make room for sleeping berths, the fuselage was widened from 66 inches to 92 inches. The fuselage was also lengthened as was the wingspan, and more powerful 1,200 horsepower Wright Cyclone engines were fitted. Two years after Smith’s initial request, the new Douglas Sleeper Transport – the DST – flew for the first time on December 17, 1935, the 32nd anniversary of the Wright brothers’ first flight. 

American recognized that the extra width of the DST allowed for the installation of an extra row of seats, increasing the passenger load from 14 to 21 – 50 percent more with very little penalty for its larger size and increased power. American quickly placed an order for the day version of the DST, which became the legendary Douglas DC-3. After entering service with American in the summer of 1936, the DC-3 quickly proved itself a superlative aircraft. Large, comfortable, and blessed with excellent flying characteristics, the DC-3 was purchased by all of the major U.S. airlines as well as several foreign carriers. C.R. Smith enthusiastically remarked that the DC-3 was the first airliner in history capable of making a profit without the need for a government subsidy, marking a major turning point leading to the economic viability of air travel. 

More than 400 were delivered before the U.S. entered the Second World War. Production did not stop then. Another 200 DC-3s were commandeered for the U.S. military while 10,000 transport versions were built as the classic C-47. The C-47 differed only in having a reinforced floor and a cargo door. C-47s were also equipped with Pratt & Whitney R-1830 engines, rather than Wright Cyclone 9s, although some DC-3s, especially those for United, also had the Pratt & Whitneys.

The C-47 became America’s most important military transport during the war, carrying troops and supplies to the war fronts around the world. It led the liberation of Normandy, dropping American and British paratroopers behind enemy lines on D-Day. It flew the “Hump” over the Himalayan Mountains, carrying cargo to Chinese and American forces, and flew coal and food into Berlin during the airlift that saved that city from Soviet domination in 1948 and 1949. License-built versions served in the Soviet Air Force against the Germans on the Eastern front, and ironically, license-built versions served the Japanese military during World War II. All told, some 16,000 DC-3s and its variants were built by the end of the war.

But that was not the end of the DC-3. Many C-47s were converted to civil DC-3s after the war and were sold to airlines around the world who took advantage of the DC-3’s excellent economics and durability, as well as its affordable price, to pioneer new routes throughout the globe with new and existing airlines. Even today, some 400 DC-3s are still working, carrying passengers and cargo; a remarkable feat 85 years in the making. 

So it’s a real treat to see these three iconic commercial aircraft sitting next to each other in the restoration hangar. It makes you consider how they have changed the world.