DH-4 De Havillands
Nine Dayton-Wright DH-4s were delivered in February 1918, but tests also indicated that many mechanical problems or “bugs” had to be worked out; for example 11 different makes of radiators were tried. Not until the 31st aircraft was completed in April was the production configuration fixed. While the basic British shape remained, along with the RAF-15 airfoil section, the internal structure was very different than the original De Havilland airframe.
The “Liberty Plane” looked warlike enough, armed with two fixed .30-caliber Marlin guns with 1,000 rounds over the engine, two flexible .30-caliber Lewis guns with 970 rounds in ten drums, and bomb racks under the wings for four 112-pound, or ten 25-pound bombs. A Wimperis sight was used for bombing, or a De Ram automatic camera was provided with 48 plates to photograph enemy positions. When adjusting artillery fire, a 50-pound wireless with a Morse code key, generator, and a wind-out trailing antenna was used. This was a transmitter only, not a receiver, and voice radio was not yet available for that war.
Flight tests in April 1918 demonstrated a top speed at full 400 hp of 124.7 mph, then as fast as many fighters. Endurance was one hour, 13 minutes at full power, and three hours at half-power. If the 19,500 foot ceiling was to be utilized, a 23-pound oxygen apparatus was provided.
Quantity deliveries from Dayton gathered force with 153 planes in May 1918, and increased to 556 by October. Fisher Body (General Motors) at Cleveland, Ohio, had been added to the program on November 7, 1917, and Standard Aircraft of Patterson, New Jersey, who had been building trainers, got a DH order on January 24, 1918. Fisher’s first DH-4 flew on June 26, and Standard delivered its first four in August. In the month of October 1918, total DH-4 deliveries reached 1,097 planes.
While four Dayton DH-4s reached France on May 6, 1918, they were from the first test batch, and judged unsuitable for front-line use. Not until August 9, 1918, did the first squadron to use the DH-4 at the front, the 135th Aero, make its first mission, with fifteen planes and General Benjamin Foulois as an observer. America had already been in the war sixteen months, with only three months left to go, yet that first sortie by American pilots in American aircraft did not even cross the front lines!
Heavy criticism would be leveled at the DH-4’s combat record. The wooden construction was considered weak compared to the duralumin tube Breguet framework, the pilot’s view upwards was blocked by the wing, and the fuel tanks lacked the leak-proof rubber covering of the Salmson and (after July) Breguet. Worst of all, the main gas tank was between the crewmen, which prevented easy communication, was a danger in crashes, and vulnerable to enemy fire. The phrase “flaming coffin” was used, although not statistically justified by actual losses.
DH-4 production in the United States reached 3,431 by Armistice Day, of which 1,213 had been received in France by the AEF. Of these, 499 had actually been delivered to squadrons on the front, 249 crashed at the front and 33 lost over the lines to enemy action. At the war’s end on November 11, there were 196 with five day bombing, five corps observation, and two Army observation squadrons, along with 157 Salmsons and 43 Breguets in the thirteen other two-seater squadrons.
The AEF also had 332 DH-4s in depots and 270 in flying schools. The U.S. Navy received 155 Dayton-built DH-4s during the war, of which 51 went to the Marines of the Northern Bomber Group in September 1918 for operations on the Channel Coast.
Of 5,000 DH-4s ordered from Dayton-Wright, 3,106 were built when production ended in March 1919. Fisher Body built 1,600 of the 2,000 ordered, and Standard just 140 of 1,000 ordered, for a total of 4,846. The government paid about $5,500 for each plane, and the first one built at Dayton is exhibited in the National Air and Space Museum.
Improved De Havillands
The British themselves, however, found the DH-9 unsuccessful and it was replaced by the DH-9A, which had wider wings, more fuel, and American Liberty engines, with deliveries to the RAF beginning in June 1918. The U.S. counterpart of this would be the USD-9A, a development pushed by the Army’s Engineering Division at McCook Field. Army engineers built two USD-9 prototypes in July 1918, and Dayton-Wright also completed two shortly afterwards. The first of five Engineering Division USD-9A models built to American manufacturing standards began flight tests September 24, 1918. Dayton-Wright also received an order in September for four USD-9As completed in April 1919 after the last DH-4s. With an enlarged self-sealing fuel tank in front of the crew cockpits, now close together, the USD-9A overcame the DH-4’s worst fault. Armament included a new .30-caliber Browning gun under the right-hand side of the cowl with 750 rounds, and two Lewis guns with 970 rounds in the rear cockpit. The 550-pound bomb load was carried in racks below the wings and fuselage, while wireless and camera equipment could be fitted to the reconnaissance version.
While the war’s end closed the USD-9A program, its main improvements could be made on rebuilt DH-4s. Dayton-Wright had delivered two improved DH-4s in July 1918; the first was the DH-4A with a modified 110-gallon fuel system, and the other was reworked by October to the DH-4B with a 88-gallon main tank forward of the pilot, the second cockpit directly behind, and the landing gear enlarged and moved forward.
After the war, the Army’s stockpile was so huge that it was cheaper to destroy most of those in Europe in the “Billion Dollar Bonfire” than to repack and ship them home. But several American aircraft factories were kept going between 1919-1923 with “maintenance” contracts modifying some 1,538 DH-4s to several DH-4B configurations. Along with the standard observation model armed with one fixed Browning and twin Lewis guns, numerous DH-4B variations were flown. These planes equipped most of the post-war Army Air Service squadrons, the Marines, the Air Mail Service, and the Border Patrol
A further development was the DH-4M (for modernized) whose fuselage was of welded steel tubing covered by fabric, assembled with parts from old DH-4s. Boeing delivered 147 DH-4M-ls from January to September, 1924, and 30 similar Marine Corps O2B-ls in March 1925, while Atlantic Aircraft rebuilt 135 DH-4M-2s. These aircraft lingered on with the Army; in April 1926, 623 of 1,510 Air Service planes were De Havillands, and two DH-4B and 78 DH-4Ms remained in 1931, the last retired in April 1932.
It is interesting to note that De Havilland’s design played a similar role in Russia, where most Red Air Force planes in 1929 were still R-ls, the Soviet-built version of the Liberty-powered DH-9A. R-1 squadrons fought tribal rebellions in Central Asia, and production actually continued until 1931! Britain’s Royal Air Force also used their own DH-9A squadrons to attack insurgent tribesmen in Iraq and Northwest India.
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