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Aviation History
1956
1956 - 0388.PDF
386 FLIGHT The upper of these two photographs shows the prototype D.H.9—a converted D.H.4; the other is a production D.H.9 with small-diameter, four-bladed airscrew. THE DE HAVILLAND D.H.9 ... casting, its use inspired by the Hispano-Suiza engine. As in theHispano-Suiza, each cylinder had a closed steel liner threaded over its whole length and screwed into the aluminium block. Thenew engine was known as the B.H.P., signifying Beardmore- Halford-Pullinger; and the first example was running on thebench in June 1916. It delivered a little over 200 h.p. The first B.H.P. engine was installed in the prototype D.H.4, whichappeared at Hendon in August 1916 and successfully underwent official trials in the following month. (The engine originallyspecified for the D.H.4 had been the 160 h.p. Beardmore, but the B.H.P. was of similar configuration and fitted into the airframereasonably well.) A new company, the Galloway Engine Co. Ltd., of Dumfries,was formed to exploit the new power unit. The engine was then named the Galloway Adriatic, and was ultimately rated at 230 h.p.The name Adriatic found little acceptance, however, and few references to it have survived. The 230 h.p. B.H.P. was put intoproduction on a modest scale at Dumfries. Events were to bring about an enormous expansion of that production. In June 1916 Sir Douglas Haig submitted an expansion pro-gramme for the R.F.C. which would provide for 56 squadrons on the Western Front by the spring of 1917. In September 1916,however, the enemy introduced his new and deadly Albatros and Halberstadt fighters, and with their appearance an urgentneed arose for substantial numbers of more and better British aircraft. In November Haig asked for an additional twentysquadrons for service on the Western Front, and by the end of the year the total number of approved R.F.C. squadrons for alltheatres of war had risen to 203, of which 97 were to be training units. It was estimated that approximately 8,000 engines would berequired to maintain these squadrons, and that British produc- tion of aero-engines would have to reach a rate of 2,000 per month.In December 1916 output was about 600 engines a month. The Air Board was re-organized in January 1917, and respon-sibility for all aircraft supplies was transferred to the Ministry of Munitions. A production programme of 2,000 engines a monthwas prepared in January 1917, but it was obvious that it could not be realized before the autumn. At that time, forty differenttypes of engine were in production, and steps were therefore taken to standardize certain engines in order to speed up pro-duction. In the 200 h.p. category it became necessary to choose from four types: the B.H.P., a six-cylinder Sunbeam (presumablythe Saracen), the Hispano-Suiza, and a vee-eight Sunbeam which was to be known as die Arab. The internal combustion engine sub-committee of the AdvisoryCommittee for Aeronautics was asked by the Air Board to assess these engines and to decide which was most suitable for mass-production. At the end of January 1917, after a thorough appraisement, the sub-committee recommended the adoption ofthe Sunbeam Arab, then a new and untried design. They also recommended the B.H.P. engine as being superior to die Saracen.Both Arab and B.H.P. were ordered in large numbers: a total of 4,400 Arabs were ordered from die Sunbeam, Austin, Lan-chester and Napier companies and from die Willys-Overland con- cern in America; and mass-production of the B.H.P. engine wasmade the special responsibility of die Siddeley-Deasy Motor Co., Ltd., of Coventry, from whom 2.000 engines were ordered.Additionally, die Hispano-Suiza was to be produced by the Wolseley company. All three of these types embodied aluminium monobloc cylinderconstruction, and die extent of die reliance placed upon what was dien a new departure may be assessed from die fact that, ofall die engines due for delivery between June and December 1917, no fewer than 4,000 depended upon die successful produc-tion of aluminium blocks. This fact, particularly where die new and untried Sunbeam Arab was concerned, so perturbed Capt.R. H. Verney of die Aeronautical Inspection Directorate diat he wrote to die internal combustion engine sub-committee, express-ing his doubts about die successful production of aluminium castings and inviting die sub-committee's attention to manydetails of die Sunbeam Arab which were still experimental. The sub-committee then reconsidered their findings, but saw no reasonto change diem; they further expressed the opinion that die expected difficulties in die production of aluminium castingswould not be insuperable. The subsequent melancholy history of die Sunbeam Arab isnot appropriate to diis narrative. Suffice it to say diat, as a failure, it was probably surpassed in magnitude only by die A.B.C.Dragonfly radial engine. The B.H.P. engine was much more of a known quantity whenit was ordered into large-scale production, for it had performed satisfactorily on test and the small numbers built by the GallowayEngine Co. had shown no serious defects. To render it suitable for mass-production, however, a number of modifications had tobe made. The changes inevitably delayed production, and brought in dieir train a number of subsequent modifications aftsrair tests of the first Siddeley-built engines. Large-scale production of die B.H.P. engine was ordered at dittime when die recommendations of die Burbidge Committee * were implemented and many members of the staff of die RoyalAircraft Factory were released to serve in the aircraft industry. In January 1917 Capt. (later Maj.) F. M. Green joined dieSiddeley-Deasy company and was appointed chief aeronautical engineer. He brought Mr. S. D. Heron widi him from Farn-borough. Capt. Green's primary task was to develop die B.H.P. engine and to adapt it for production; Heron was given die taskof developing die R.A.F.8 radial engine, which was ultimately to emerge as the Armstrong Siddeley Jaguar. Mr. J. D. Siddeley himself took a hand in die development ofdie B.H.P. engine, and it was at his instigation mat the cylinder design was modified to incorporate an open steel liner with ashort screw-diread on its upper end by which it was screwed into the cast aluminium cylinder block. (The original B.H.P. enginehad a closed liner direaded over its entire lengdi.) As modified for mass-production by die Siddeley-Deasy com-pany die engine was named Siddeley Puma. But die modifications which resulted in die Puma did not alone ensure trouble-freeproduction. At an early stage, Capt. Verney's prognostications about die difficulties likely to be encountered in die production ofaluminium cylinder blocks were realized. By July 1917 sufficient Puma cylinder blocks were available to permit an output of 100engines per month, but it was soon found that 90 per cent of the cylinder blocks were faulty. A report made diat month tothe Air Board stated diat defective castings accounted for 20 per cent of the rejects, porousness for 35 per cent, and damages sus-tained during machining for a furdier 35 per cent; and a few which had no obvious flaws failed on test. Trouble widi die aluminium castings persisted throughout diesummer of 1917 and was responsible for a six-month set-back to the production schedule. These difficulties may have been diereason why, in order to ensure the availability of some engines, the Galloway Engine Co. experimented widi a version of the B.H.P.which had cast-iron cylinders. It appears diat die difficulties with aluminium castings were ultimately resolved, for productionof die engine began to gain momentum. A further difficulty was encountered when it was found that die exhaust valves wereprone to burn out rapidly, and more delays occurred while diis fault was remedied. Production did not really get under way untildie spring of 1918. During die first uiree months of uiat year *The Burbidge Committee (Chairman: Sir Richard W. Burbidge, St.),was set up by the War Office in March 1916 to enquire into the func- tions of the Royal Aircraft Factory. Among its recommendations wasone to the effect that the Factory should confine its activities strictly to research and should not build even experimental aircraft.
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