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Aviation History
1948
1948 - 1518.PDF
334 FLIGHT SEPTEMBER I6TH, 194S MACH PLUS John Derry's Wonder- ful Achievement in the de Havilland 108 Britain's supersonic com- bination—the D.H. 108 high- speed research aircraft and John Deny. Though some time is likely to pass before a British piloted aircraft ex- ceeds the speed of sound under its own power in sustained level flight, we are at last tan- gibly reducing America's lead in ultra-high-speed flying. ONE of the most efficacious tonics administered toBritish aviation in recent years is the news thatMr. John Derry, de Havilland test pilot, has ex- ceeded the speed of sound in a D.H. 108 research aircraft. Flight adds its congratulations to the many received by Derry and his company, at the same time acknowledging the part played by the Ministry of Supply in sponsoring the construction of a machine which now takes its place iu aeronautical history as the first British aircraft to exceed a Mach Number greater than unity. It is gratifying, more- over, to record a pronouncement by a spokesman of the U.S. Army Air Force, who described Derry's achievement as " most important," adding that, although the Bell XS-i had flown much faster than sound many times in controlled flight, the de Havilland machine more nearly approached a conventional and practical aircraft. (In all fairness the veracity of this statement must be questioned, for the Bell, although utilizing an unconventional power plant, namely, a battery of liquid fuel rockets, has straight wings, whereas the 108 has a swept-back wing and is further unconven- tional in having no tailplane or elevator.) In conversation with Derry last week at the Ministry of Supply, it was learned that the historic flight took place at about 10 a.m. on the clear morning of Monday, Septemer 6th, between Farnborough and Windsor. Derry had no firm intention of attempting to exceed Mach 1, the declared purpose of his flight being the collection of data at speeds above Mach 0.96, which he had already attained. He put the 108 into a dive at 40,000ft, steepening the angle of descent as the hand of the Machmeter approached the magical figure " 1" and holding the dive until the needle passed the limit of its indication. The outside air tempera- ture was —30 to —35 deg C. Confident that he had exceeded the speed of sound (the A.S.I, was reading 400 m.p.h., equivalent to nearly 700 m.p.h. true air speed), Derry pulled out and headed for Hatfield. He had ex- perienced no unusual sensations, but as speed built up the controls became very heavy, despite the power-boost system now installed. As the 108 decelerated to Mach 0.96 control characteristics returned to normal. No buffeting was ex- perienced and no instability, excepting that which may heve been manifested in the tightening-up of the controls. It was made clear at the Ministry of Supply that the phrase '' apparent Mach Number'' used in a preliminary communique implies no doubt of success, for the Mach- meter was calibrated before and after Derry's flight. As the man primarily responsible for the design of the 108, Mr. R. M. Clarkson considers the next step in the M. of S/D.H. high-speed de- velopment programme to be consolidation of what is already known. The airframe of the 108 was not designed to with- stand the loads of supersonic flight in the dense air at low altitudes, nor is it proposed to install a Ghost turbojet in place of the specially rated Goblin, for, though this might permit Mach Numbers above 1 to be achieved in level flight, very extensive modifications would be entailed. That the 108 is capable of higher Mach Numbers is almost certain, but whether these could be achieved with the machine under full control will not be known until further checks have been made. The supersonic 108 is "VW120," the machine in which Derry this year captured the 100-kilometres closed-circuit record with a speed of 605.23 m.p.h. and in which, on the same occasion, he recorded straight-and-level speeds of the order of 640 m.p.h. The third of its kind, it differs from: the second prototype, which broke up in the air, in having certain structural modifications of a comparatively minor nature, a stronger and cleaner cockpit enclosure, a more pointed nose, ejector seat, power controls and a Goblin turbojet of higher rating. R.A.F.A. REUNION FESTIVAL ""THE Royal Air Force Association's annual Festival of-L Reunion, held on Sunday at the Albert Hall, passed off in spirited style, due in great measure to the able productionof S/L. Ralph Reader, M.B.E. (of "Gang Show" fame). The R.A.F. in past and present days was represented by membersof the 650 branches of the Association, serving airmen and airwomen and Halton apprentices. Appropriately, music was*provided by the Central Band of the R.A.F., under the Direc- tor of^MtrSIcT"S7ML. A. E. Sims. Items reminiscing on old wartime and pre-war days appealedgreatly to the thousands of ex-members of the R.A.F. and their families present, ana -the professional artistes appearingwere deservedly well received. The Festival was concluded by a service conducted by the Chaplain-inrChief of the R.A.F.,the Rev. J. A. Jagoe. 7 B IO
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