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Aviation History
1955
1955 - 1281.PDF
FLIGHT, 2 September 1955 395 Gyron At the time of writing it is almost certain that this great axial turbojet will make its public bow at the coming S.B.A.C. exhibition. Nevertheless, in the absence of ministerial con- firmation, we can record here nothing that is not already known. The existence of the Gyron was revealed two years ago, and at that time development had al- ready reached an advanced stage. In the original statement was the announcement: "It may be made known that the Gyron was giving very high thrust within the first few weeks of running . . . also that it has given satisfactorily low specific consumption and a high degree of reliability.'' It is also known that the engine is of an excep- tionally simple and rugged nature, yet has a very low weight for its power. It is, in fact, not merely a bigger version of the axial engines already in service but the precursor of a new generation of turbojets, for which a new generation of airframes must be built. In these airframes it wil! be often supplemented by rocket power, and it is clear that de Havilland, with characteristic foresight, are developing versions of the Gyron and Spectre in parallel, to form a matched team for supersonic military aircraft. In such applications the Spectre would dominate at altitude, the Gyron providing increased endurance. Test-bed time has now reached a very satis- factory figure, with a number of engines avail- able. The first flight was on July 7th last, with an engine mounted in the lower port position on the first Short Sperrin prototype. Flight trials, which are now taking place from Hatfield, are progressing well, and the performance and hand- ling are well up to expectations. Centrifugal Turbojets No significant changes have been made to the Goblin turbojet, which is in use in all parts of the world and remains in production as die power unit of the Vampire Trainer. The larger Ghost is also in full produc- tion, for the several versions of Venom and Sea Venom. The engine illustrated at upper right is the latest that can be published, although ratings DGt.4 and 5 (Ghost 104 and 105) are known to exist, and no doubt represent a significant advance on their predecessors. Above: de Havilland Ghott 101 turbojet. Single-sided centrifugal comprwior, 10 combustion chambers and single-stage turbine. Diameter, 53in; length. 130.5in; dry weight, 2,175 Ib; ma« flow, 88 Ib/sec; pressure ratio, 4.5:1; maximum thrust, 4,850 Ib at 10,250 r.p.m. with s.f.c. of 1.09 Ib/hr/lb. Below, da Havilland Goblin 15 turbojet. Single-stage, single-sided centrifugal compressor, 16 combustion chambers and single-stage turbine. Diameter, 49.85in: length, 100.5m; dry weight, 1,629 Ib; mass flow, 63 Ib/sec; pressure ratio, 3.67:1; maximum thrust, 3,500 Ib at 10,750 r.p.m. at sea level; sXc, 1.14 Ib/hr/lb. . «.- . .... , Rocket Motors Both the pioneer de Havilland rockets were assisted-take-off units. The first, named Sprite, was designed for permanent instal- lation in the Comet 1, and obtained thrust by injecting a mixture of concentrated hydrogen peroxide and a catalyst into a reaction chamber, from which the propellants emerged as a brownish jet of superheated steam. From the Sprite was evolved the Super Sprite, illustrated. Not only does this unit have larger tanks, but the peroxide is decomposed by inject- ing it through a metal-gauze catalyst. The Super Sprite also has a higher specific impulse, since kerosine is added to the decomposition products and burns therein. The drawing shows the jetti- sonable nacelle which is now in production for a British military aircraft, one such unit being attached under each wing. Last year the Super Sprite became the first liquid-propellant aircraft rocket to pass a service type-test, and jettison trials have since taken place. Earlier this year, the de Havilland company were able to announce the existence of the Spectre. This is another liquid-propellant air- craft rocket, and it may be assumed to be of higher output than the Super Sprite. Unlike its pre- decessors, the Spectre is intended, in some appli- cations at least, for permanent installation in supersonic fighters, in which aircraft it would be matched with a Gyron turbojet. Such a com- bination of rocket and jet power can be shown to provide unmatched supersonic and high- altitude performance. Although no details of the Spectre may yet be published it is fair to expect it to be a pump-fed unit, in view of die increased duration of firing. Considerable test-bed firing has been successfully completed, and flight trials are imminent. de Havilland Super Sprite a.t.o. rocket pack (photograph shows basic rocket motor). Basic motor: overall dimensions, length, 117£in, diameter. 20^in. Empty weight, 620 Ib ±2^ per cent; fuelled weight, 1,460 Ib ±2i per cent. Standard maximum rated thrust, 4,200 Ib for 40 seconds total duration (see thrust curve); total impulse, 120,000 Ib/sec. Propellants: 57 gal hydrogen peroxide at 80 to 85 per cent concentration and 5 gal kerosine or wide-cut gasoline. Feed by 3,690 cu in nitrogen initially at 2,900 to 3,100 Ib/sq in. Nacelle: approximate overall dimensions, length, 150in, height, 32in and width 28in. Total weight nacelle and fuelled motor, about 1,900 Ib; fall weight of expended nacelle, about 1,100 Ib.
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