Flown as an observation plane and as a bomber, the DH4 was the only American-manufactured aircraft to enter combat during the First World War.
“Icons of Aviation History” is a diary series that explores significant and historic aircraft.
DH4 on exhibit at the Smithsonian Air and Space Museum
When the United States finally entered the First World War in April 1917, it was completely unprepared. The US Signal Corps had only 132 airplanes used for reconnaissance and artillery spotting, and all of them were hopelessly obsolete.
But the French and British allies were eager to take advantage of America’s vast production capability as quickly as possible, and a commission was set up to decide which Entente aircraft designs could be produced in US factories. After considering the French SPAD XIII fighter, the Italian Caproni bomber, and the British SE5a fighter, they settled on the De Havilland DH4 bomber, which had the simplest structure, would be the easiest to mass-produce, and could use the newly-developed American V-12 Liberty engine (designed and tested in just six weeks).
The De Havilland DH4 had been introduced in 1916, when the need became clear for a better-defended spotter/reconnaissance pane that could also deliver a useful bomb load. Powered by the Rolls-Royce Eagle engine, the DH4 carried 460 pounds of bombs under the wings, a single Vickers machine gun that was fired forward through the propeller by the pilot, and twin Lewis guns mounted on a moveable ring that was fired by the rear observer. The observer could also carry a large-format camera for photo-reconnaissance, and use a wireless telegraph set to send corrections directly to artillery batteries on the ground. British squadrons equipped with DH4s also pioneered many bomber tactics, including wedge-shaped formations that would bomb en masse at the flight leader’s signal, and which used interlocking fields of machine gun fire to defend the formation against enemy fighters.
The DH4 was, however, always hampered by a shortage of Eagle engines, and although the British tried substituting more readily-available engines like the BHP, the Siddeley Puma and the Fiat, none of these were as good as the Eagle. So when the US entered the war and the Liberty engine, manufactured by the Packard automobile company, became readily available, the British pushed to move production of the DH4 to the United States.
The US began production of the DH4 “Liberty Plane” in November 1917. Three companies manufactured the plane under license from Airco—the Wright Company in Dayton OH, the General Motors Fisher Body Plant in Cleveland, and the Standard Aircraft Corporation in Paterson NJ. The American versions carried 322 pounds of bombs and were armed with two .30-caliber Marlin machine guns in front and two .303-caliber Lewis guns in the rear. They had a speed of 125mph and a range of 400 miles.
One difficulty that was never really solved lay with the DH4’s fuel system. The gas tank, which lay between the pilot and the observer, was pressurized and had rubber fuel lines, and it tended to explode if hit. Pilots in France dubbed it “The Flaming Coffin”. The British replaced their pressurized tanks with wind-driven pumps, but the Americans, not wanting to alter their manufacturing process and slow production, stayed with the older design for quite a long time.
The United States produced about 9,500 DH4s, but only 1885 of these actually reached France before the war ended; they began flying combat missions in August 1918. They saw service with the French and British (the British also continued to produce their own versions equipped with Rolls-Royce Eagle engines) as well as with the American Expeditionary Force: DH4s flew with eight US Army reconnaissance squadrons and five bomber squadrons, as well as four Navy patrol units. By 1918, plans were being made for the DH9, an improved version, but this proved to be inferior to the DH4 and was never given priority with the Entente during the war.
After the war, most of the European nations switched over to newer improved DH9-A designs. (The Russians, who had been supplied with some DH4s during the war, produced their own post-war copy made by the Soviet Polikarpov design bureau.) But the United States, with limited military budgets and with a large number of undelivered stocks on hand, stayed with the DH4, flying it operationally until the 1930s. The large number of DH4s that remained in France at the end of the war were considered “surplus”, and rather than go to the expense of returning them to the United States, the Army decided to destroy them all—which came to be known as “The Billion-Dollar Bonfire”.
Some DH4s were modified by the Army for use in post-war experiments in air-to-air refueling. The Army also sent a number of DH4s to New Mexico and Texas as part of the Border Air Patrol, to prevent any cross-border raids by Mexican bandits and revolutionaries. Civilian versions of the DH4 were adapted by the US Post Office for use as airmail carriers, replacing the front cockpit with a cargo compartment. Some were also used by the Interior Department to patrol for forest fires, and when “surplus” DH4s became available to civilians, they were used as passenger planes, crop dusters, and barnstormers. A few versions of the DH4 were fitted with radial Wright R-1 engines.
Today, there are only around a dozen surviving DH4s left. The National Air and Space Museum displays the original prototype American-built DH4, with a Packard Liberty engine, built in October 1917. It was used as a test plane for various configurations until April 1919 when it was retired and turned over to the Smithsonian. It is exhibited in combat configuration, with a bomb load and with wireless transmitter and aerial cameras used for photo-reconnaissance missions. The US Air Force Museum has a DH4-B model that was manufactured by GM in Cleveland. And the National Postal Museum in Washington DC also has a B model on display.
NOTE: As some of you already know, all of my diaries here are draft chapters for a number of books I am working on. So I welcome any corrections you may have, whether it's typos or places that are unclear or factual errors. I think of y'all as my pre-publication editors and proofreaders. ;)
