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Aviation History
1956
1956 - 0387.PDF
Typical proaucuon-type D.H.9, with B.H.P. engine. THE DE HAVILLAND D.H.9 HISTORIC MILITARY AIRCRAFT No. 12 Parti By J. M. BRUCE, M.A. STRATEGIC bombing had its beginnings in the operations ofNo. 3 Wing of the Royal Naval Air Service. From theoutbreak of the 1914-18 war the Admiralty had been alive to the need for long-distance bombing attacks against naval andmilitary centres lying within German territory, particularly those works in the Saar which were believed to be producing steel forU-boats. But the means of launching such attacks were not available untilthe spring of 1916. By that time the Sopwith lj-Strutter and Short Bomber were in production: the former, in its single-seatbomber version, could carry four 56-lb bombs; the latter could transport the substantial load of four 230-lb or eight 112-lb bombs. The first H-Strutters became available in the spring of 1916,and at the beginning of May of that year Captain W. L. Elder, R.N., was sent to France to prepare for the arrival of the newbombing unit which was to be known as No. 3 Wing. It was hoped that by July 1st, 1916, the Wing would be equipped withtwenty lJ-Strutters and fifteen Shorts, and that the ultimate strength would be one hundred aircraft. Unfortunately for the unit, the first day of that July had beenselected as the date of the launching of the great Somme offensive, and the R.F.C. was short, by no fewer than twelve squadrons, ofthe number of aeroplanes estimated to be required to meet the needs of the Army. The War Office appealed urgently to theAdmiralty to hand over as many aircraft as the R.N.A.S. could spare; the appeal was promptly and generously answered by thetransfer of a number of Sopwith l|-Strutters, many of which had been destined for No. 3 Wing. Thus it was not until October 1916 that No. 3 Wing was ableto begin operations on a sizable scale. Attacks were made on iron and steel works at Hagendingen, Volklingen, St. Ingbert andDillingen, but operations were hampered by unfavourable weather, and No. 3 Wing was disbanded in the spring of 1917without having scored any resounding successes. Some months later, when the enemy began his systematic nightbombing attacks on London, it was officially decided to launch counter-attacks against targets in Germany, and the concept ofstrategic bombing was hurriedly resuscitated. At the beginning of October 1917, Maj.-Gen. H. M. Trenchard (later Marshal ofthe R.A.F. Lord Trenchard, whose death occurred last February) formed the 41st Wing, R.F.C., under Lt.-Col. C. L. N. Newall.The D.H.4s of No. 55 Sqn., the F.E.2bs of No. 100 Sqn., and the Handley Page 0/100s of No. 16 (Naval) Sqn. were based atOchey, within reach of an area containing many vital industries. The attacks made by these squadrons on such towns as Saar-briicken, Volklingen, Kaiserslautern, Mannheim, Cologne, Mainz, Stuttgart and Coblenz damaged the enemy's industrial plantsand lowered the morale of the workers in those towns. In the weeks immediately preceding the establishment of theIndependent Force, R.A.F., two new squadrons joined the 41st Wing. No. 99 Sqn. arrived at its aerodrome in France on May3rd, 1918, No. 104 on May 19th. No. 99 made its first opera- tional sortie on May 21st, and No. 104 on June 8th. Bothunits were day-bomber squadrons, intended to augment No. 55 Sqn., whose D.H.4s had given sterling service in the 41st Wing's THIS, the twelfth article in Mr. Brace's important series which hasappeared periodically in "Flight" since October 1952, tells the story of a World War I bomber type which, though it did not win the affection ofpilots to the same decree as its successor the D.H.9A, saw service in large numbers. The author wishes to acknowledge assistance he hasreceived from Mr. A. R. Weyl, A.F.R.Ae.S., and Mr. D. B. Robertson in the compilation of this history. daylight operations; and both were equipped with a new type ofaircraft, the D.H.9. When, therefore, the Independent Force officially came intobeing on June 6th, 1918, it consisted of Squadrons Nos. 55, 99 and 104 of the 41st Wing, and Nos. 100 and 216 of the 83rd Wing.So markedly had opinion swung in favour of strategic bombing that an ultimate strength of sixty squadrons was envisaged.It might have been reasonable to expect the D.H.9, as a latei design, to have been an improvement on the D.H.4. That it wasnot was unfortunate enough; but that it was ordered and put into service with its shortcomings known was a tragedy comparableto the continued production and use of B.E.2Es long after they had been outclassed.The war-time fortunes of the D.H.9 were so intimately con- nected with its standard engine that it is necessary to begin byexamining the history of the power unit. Perhaps, unexpectedly, that history began in France, in the summer of 1913 when ayoung British engineer named F. B. Halford examined a new water-cooled vee-eight engine of 150 h.p., built by the Hispano-Suiza company to the design of M. Birkigt. The Hispano-Suiza engine was of unusual construction, for each bank of cylinders wasa monobloc aluminium casting into which steel liners, threaded over their whole length, were screwed. At that time it was cus-tomary for water-cooled aero-engines to have individual steel or cast-iron cylinders with sheet-metal water-jackets: the Hispano-Suiza engine therefore represented a considerable advance in design and constructional methods. It was probably not the firstliquid-cooled aircraft engine to have aluminium cylinders, but it was indisputably the first successful one. Halford immediately recognized the virtues of the new engine,and on his return to England he advocated the production of the Hispano-Suiza under licence. The engine had also been favour-ably reported on by Lt-Col. H. R. M. Brooke-Popham, who had examined it in Paris. The first British order, for fifty examplesof the French engine, was placed in August 1915; and negotia- tions—which proved to be protracted—began with a view to itsmanufacture in Britain. British production of the Hispano-Suiza did not begin untilthe spring of 1916, by which time Halford had nearly completed a new engine of his own design. He had earlier been largelyresponsible for increasing the output of the Beardmore six- cylinder engine from 120 h.p. to 160 h.p.: that development hadbeen" made in collaboration with T. C. Pullinger, managing director of Arrol-Johnston, Ltd., the company responsible for themanufacture of the Beardmore engine. Early in 1916, in collaboration with Sir William Beardmoreand T. C. Pullinger, Halford began work on a new six-cylinder in-line engine which incorporated an aluminium monobloc
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