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Aviation History
1953
1953 - 1178.PDF
334 FLIGHT, 4 September 1953 K.L.G. thermocouple harness for Dart. Lucas turbine-driven re-heat fuel pump. PROPRIETARY EQUIPMENT One of the latest patterns is the TBS 70 starter, which is a three-shot unit designed for starting large turbojets. It has been found possible to pack three cartridges into the "bullet" fairing at the front of an en gine, so greatly increasing the flexibility and utility of the unit. The TBS 70 is used on the re-heat Avon RA.7R and also on the Nene of the Sea Hawk. Delaney Gallay, Ltd., Vulcan Works, Edgware Road, London, N.W.2 (Stand 162), have already developed a most ad vanced oil cooler for a project which is still secret. This unit, which is made in light alloy, operates at high pressure and the cooling is effected by a flow of fuel from die main tanks of the vehicle. Cross-flow heat exchangers continue to occupy much of die company's attention, and the two most recent publisnable units—those for the Viscount and Britannia—are made entirely in stainless steel. The Britannia unit is now open for public display; it is used to provide hot air for wing de-icing. Dotvty Equipment, Ltd., Arle Court, Cheltenham, Glos. (Stand 205), now pro duce a considerable variety of fuel system components. Prominent are a range of high-performance pumps and the Spill- system with which they may be associated. The Spill fuel system is capable of giving excellent fuel atomization over the entire working range of the engine, since the air and fuel velocity for this purpose remains sensibly constant irrespective of the mass flow and power output. A controlled spill of fuel is thrown back from die burner through an annular orifice at the rear of the swirl chamber. By so doing, a continuous high rate of fuel supply can be maintained to the burner of which a progressively reduced proportion is "spilled" as the engine power is increased. Of die current Dowty pumps, the Type ENG.129, for the Sapphire (and, licence- produced by Thompson Products, for the Curtiss-Wright J65) is typical. This is a multi-plunger unit, and among its many good features may be listed: the use of fuel-pressure applied to the rotating parts to cancel out factional loads and reduce wear, and the manner in which "Michell- block"-type slippers a?e used to impart the eccentric track-ring motion to die plungers without the need for lubrication. An even later pump, of yet greater capacity, is the Type ENG.300, which will be shown at Farnborough for the first time; Type ENG.129 delivers up to 1,575 gal/hr of kerosine at 1,000 lb/sq in. at 3,500 r.p.m. Flight Refuelling, Ltd., Tarrant Rush- ton Airfield, Blandford, Dorset (Stand 7), have announced three entirely new items. Particularly attractive is die Mk.17 in-line refuelling valve, specially designed to meet die requirements of a fine shut-off valve, and to obviate special tank bolt rings and inaccessible valves. The valve—claimed to be the lightest in the world, at 28 oz—is electrically operated, consuming but 3.1 W. It operates on die pressure-differential principle, die valve being actuated by a solenoid and bellows. A typical application is in die refuelling line to a tip-tank, where a normal shut- off valve is impracticable. The Mk.17 can pass 50 gal/hr, with a pressure drop of 8 to 9 lb/sq in. K.L.G. Sparking Plugs, Ltd., Putney Vale, London, S.W.I5 (Stand 4), have, during the past year, finished development on such diverse products as: high-energy igniters for the high-flying Rolls-Royce Avon and Bristol Olympus; high-frequency igniters for the Plessey monofuel starter and the Napier Nomad compound engine; sparking plugs for the Vincent Picador, D.H. Gipsy Major and Alvis Leonides; and jet-pipe thermocouples for the Fairey Gannet and Vickers Viscount. The last-named unit, developed in con junction with Rolls-Royce, uses six thermo couples (chromel/alumel) insulated widi K.L.G.'s new "Bluestone," which has great resistance to thermal shock and mechanical impact. The head of each diermocouple is further sealed by a vitreous compound, and die leads are insulated by P.T.F.E. oversheathed widi high-grade, stainless- steel flexible conduit. The unit is illus trated on this page. Joseph Lucas (Gas Turbine Equip ment), Ltd., Willesden Junction, N.W.IO (Stand 157), make fuel systems for all types of turbine-driven aircraft, and a creat many new components will be on view at Farn borough. All diese units reflect the necessity to develop governors and control devices which function accurately irrespective of fuel density; wide-cut gasoline is die fluid most commonly dealt with. One such unit is a constant-pressure gear pump, widi a mechanical governor for use with spill-flow systems. Another is a simplified combined control unit for expendable turbojets which includes an altitude control, a spill-flow valve to control pump delivery, a propor tional-flow dirotde and a shut-off cock. Among straightforward fuel pumps, the D-size is of impressive performance. This is a variable-stroke, multi-plunger unit, the capacity being adjusted by a servo control. Delivery at 3,500 r.p.m. is no less than 1,680 gal/hr at 2,000 lb/sq in. Another novel and compact exhibit will be a re-heat pump, designed to pump fuel to die after burner of a powerful turbojet. The small centrifugal impeller is driven from a single-stage turbine fed with hot, com pressed air tapped from the main-engine compressor delivery. Illustrated on this page, this tiny unit can deliver over 2,000 gal/hr at pressures in excess of 600 Ib/sq in—a remarkable performance for a small, centrifugal single-stage pump. The Plessey Co., Ltd., Ilford, Essex (Stand 15), and Plessey International, Ltd. (Stand 14), are large-scale manufacturers in the fields of radio, electric power, elec tronic, hydraulic, engine-starting, and press-tool work. A most important item is the liquid-fuel starter for large gas- turbines, in which sphere Plessey were pioneers; they can at present claim to have the only such unit to have passed an M.o.S bench test. The fuel used is iso-propyl nitrate, which is decomposed under heat and pressure without the use of any oxidant or catalyst. The resulting exhaust is led to a single- stage turbine, at a temperature no greater dian 600 deg C. In use die whole arrange ment has proved very successful; the fuel is readily available, safe, stores well, and is quite cheap, the power output (the present standard types are of some 70 and 150 h.p.) can be varied by altering the fuel throughput, and the installed starting system shows many other advantages in flexibility and lightness compared with odier systems. Next week, Plessey will show the latest, more compact version of the unit, and it should be noted that a licence is held for its production in America by the Hamilton Standard division of United Aircraft. After some three years' development in die Plessey Starter and Monofuel laboratories the first liquid-fuel units are now going into production. The actual model ex hibited is the LTSA 70, of about 70 b.h.p., which has been successfully put tiirough M.o.S. type-tests. It is shown below. Rotol, Ltd., Cheltenham Road, Glouces ter (Stand 57). It is clear that, if dispro portionate consumption occurs between fuel tanks disposed over the wings and fuselage of any aircraft, there will be a corresponding loss in stability. This can be serious in high-speed aircraft—in which, in any case, rate of fuel consump tion is high—and Rotol have developed a fuel-flow proportioner to obviate this trouble. Fuel from each tank is led to a meter ing unit consisting of an eccentric-vane pump, the volumetric displacement of which is proportional to the capacity of
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