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Aviation History
1956
1956 - 1434.PDF
586 / FLIGHT, 5 October 1956 A Sopwith /'/i-Strutter in Ameri- can service. HISTORIC MILITARY AIRCRAFT: No. 14 PART II By J. M. BRUCE, M.A. THE SOPWITH H-STRUTTER V N those anxious weeks preceding the Battle of the Somme I the need for fighting aircraft in France was so great that * No. 70 Sqn., R.F.C., went overseas by Flights as soon as aircraft became available. The l|-Strutter had been put into production for the R.F.C. early in 1916; the first contractors were Ruston, Proctor and Co., Ltd., of Lincoln, and the first deliveries were made to No. 70 Sqn. On May 24, 1916, "A" Flight went to France; but "B" Flight did not cross the Channel until June 29 and did not reach its base at Fienvillers until July 3. On July 30 "C" Flight arrived in France. This third Flight of No. 70 Sqn. was equipped with ex- R.N.A.S. lj-Stmtters. As such they were armed in accordance with Admiralty practice, which meant that their gun-synchron- izing gears were of the Scarff-Dibovski type. Lt-Cdr. V. V. Dibovski, an officer of the Imperial Russian Navy, had brought his ideas on machine-gun synchronizing to the notice of the R.NAS. in January 1916. These ideas were quickly developed and realized by Warrant Officer F. W. Scarff, a gunner on the staff of the Air Department of the Admiralty. If all reports are true, there can be little doubt that the H- Strutter was fitted with a greater variety of machine-gun syn- chronizing and interrupter gears than any other aircraft used by the British aerial forces during the war. It seems tolerably certain that the machines built for the R.N.A.S. had the Scarff-Dibovski gear as standard equipment. Other types of synchronizing gear, however, were fitted to the H-Strutters delivered against War Office contracts. According to the official history*, the first li-Strutters delivered to the R.F.C. were fitted with the Vickers-Challenger gear, and the machines of "A" and "BM Flights of No. 70 Sqn. were so equipped. The same authority states that the H-Strutters of No. 45 Sqn. R.F.C. (which arrived at Fienvillers from England on October 15, 1916) had the Scarff-Dibovski gear, but accord- ing to Capt. Norman Macmillan, who served with No. 45 Sqn., the unit's early machines were fitted with the Ross interrupter gear. The latter gear was evolved by F/Sgt. Ross, an N.C.O. serving with the R.F.C. in France, and it was a true interrupter gear. As such it slowed down the gun's rate of fire to a marked degree. When the Ross gear was fitted, the Vickers gun retained its normal ground trigger; in real emergencies, when a high rate of fire was demanded, pilots used that trigger and risked damaging their own airscrews. Captain Macmillan has recorded that he knew of no case of airscrew disintegration resulting from this rather desperate action. There can be no doubt that the Ross gear was fitted to some li-Strutters, for Maurice Baring recorded on May 8, 1917: "Van Ryneveld now is commanding No. 45 Squadron, which fly Sopwith two-seaters. He has only one Ross interrupter gear." One is tempted* to wonder whether the machines delivered to No. 45 Sqn. may have had the Scarff-Dibovski gear at the time of delivery, only to be re-equipped with the Ross gear at an early stage in their service. Unless the Admiralty actually sought to * "The War in the Air," Vol. 11, page 163. reclaim the Scarff-Dibovski mechanisms from the Sopwiths, thereby necessitating the change, it hardly seems likely that such a modification would be made purely for its own sake at a time when synchronizing gears of any kind were scarce and the air- craft were so urgently needed at the front. A little later, the Sopwith company produced its own gun- synchronizing gear. This was the Sopwith-Kauper gear, which has been described as a development or improvement of the Ross gear. There may have been a similarity in the physical appear- ance and even in the functioning of the two gears, but the Sopwith-Kauper mechanism was a synchronizing device which positively fired the gun instead of interrupting its fire as the Ross gear did. Considerable numbers of l^-Strutters were fitted with the Sopwith-Kauper synchronizing gear. In matters of armament the lj-Strutter pioneered not only gun-synchronizing gears for fixed armament but also (and equally importantly) a new type of mounting for the observer's free gun on the rear cockpit. Once again a fine piece of equipment which was rapidly standardized originated from the R.N.A.S., for the outstandingly practical gun-mounting had been designed by W/O. Scarff, the same Scarff who had been responsible for developing the Scarff-Dibovski synchronizing gear. Scarff's first ring-type mounting for a free Lewis gun, known as the Scarff No. 1 ring mounting, was not adopted for general use, but it was an ingenious device and an enormous advance over all earlier mountings. Not only did it provide the gunner with a means of moving his gun quickly but it incorporated a gun-sight which automatically allowed for "own" and "enemy" speeds and gave the gunner the correct allowance for deflection (or, in the jargon of a later war, angle off). Facilities for training in the use of the Scarff No. 1 mounting could not be provided; consequently it had to be abandoned. It was followed by the Scarff No. 2 ring mounting, and it was this device which was fitted to the IJ-Strutters ordered by the Admiralty. The gun was carried on a U-shaped bridge of steel tube, mounted centrally and flexibly at the mid-point of the base of the U. The ends of the legs of the U were hinged to a metal ring, and the U-member could be elevated from the horizontal through a considerable arc. At about the mid-points of the legs of the U, quadrantal guides were fitted; these guides had one rack-toothed edge, the teeth being engaged by pins in the legs of the U-member. The pins could be retracted by the operation of a lever (somewhat similar to the brake-lever of a motor cycle) mounted on the cross-piece of the U near the gun; and when the pins were disengaged the U-member could be elevated and lowered. This vertical movement was made against rubber cord in tension. The ring to which the U-member was attached rolled freely about a fixed ring: it could rotate through 360 deg but was locked and unlocked at any point by the same lever which- controlled die elevation of the U-shaped bridge. The fixed ring was rigidly attached to the fuselage. Thus a gunner could swing his gun in elevation and azimuth. H« stood with his left hand on the locking lever, his right holding the Lewis gun, and a target could be followed instantly and
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