FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1957
1957 - 1356.PDF
FLIGHT (1) High-pressure gas cylinder. (2) Pressure reducing valve. (3) Scarting valve. (4) Free piston. (5) Oit recuperator. (6) Bursting disc. "1 Filter.ft (8) Relays. (9) Servo valves. (10) Actuating cylinders. (11) Telemetering potentiometer. (12) Feed-back potentiometer. (13) Charging valve. (14) Overboard dump.* Described in the text under "M.o.S." on a later page, the CTV-5 moving-wing servo is illustrated in the diagram above. The sketches on the right show boost mountings on the English Electric Thunder bird. The rear lugs are heavy L-shaped anchorages, and the forward attachments lie under hinged covers in the control fairings. ON THE GROUND... Guided Weapons (continued) single shaft driving both the alternator anda suitable device capable of absorbing sur- plus power, so that the alternator canabsorb any fraction of the total power in- put. Another method is to employ athrottle, but this becomes difficult when using a "dirty" propellant such as cordite.When using hydraulic oil as the driving medium it is possible to have a simplethrottle, and D.H. have devised a design with extreme sensitivity. When very smallpower is required the pressure-drop im- posed on the oil would cause the latter toget very hot, and so for fine metering at minimum power the capacity of the motoritself is varied. It is common practice to drive two typesof power supply—electric plus hydraulic— from a single shaft, or to have two al-ternators, operating at different frequen- cies, in tandem. For test work it is usefulto have a continuously rated machine, driven by oil or from a constant-speedshaft. A photograph illustrates a range of D.H.Propellers' missile alternators. The vast majority of British test and productionguided weapons use this company's altern- ators, and D.H. have thereby acquiredmassive experience. Some of our weapons impose very peculiar electrical loads, andD.H. have evolved a technique for elec- tronically controlling the waveform and fil-tering out almost all distortion. The following accessories were on dis-play: Power unit. A single-stage axial turbine was mounted on the rotor shaftof an alternator, the latter being sur- rounded by a stack of condensers. TTie lat-ter were potted in plastic, and D.H. have potted rectifiers and thereby—they say— improved their rating. A rotary switchabove the power unit served to programme events. Incidentally, the turbine is madeas large as the weapon size allows, to im- prove efficiency; for the future, however,very tiny wheels may be used, turning at extremely high r.p.m. Power electronics. This unit had a castframe filling the Firestreak cross-section, retained by four transverse bolts. Nine"boxes" were mounted thereon, some of them being potted; other details includedsmall-diameter stainless-steel pipes, ap- parently for cooling air, held by solderedend-plates bolted to the frame, and tight binding of all wire looms to resist thehigh launching acceleration. Rate-gyro. Obviously the Firestreak isroll-stabilized, but a rate-gyro alone could not position-stabilize. Housed in a sheet-covered box were three gyros, driven elec- trically and fed with air by stainless intaketubes. Air bottle. Precision welded from steelsheet, this unit was of toroidal form, roughly 9in diameter with a 9in parallel-sided sec-tion, and a hole in the middle—presumably to fit over the rocket-motor exhaust tube.Four mounting bolts were provided at one end. Storage pressure must be very greatsince the air must drive the alternator and —because a twin starting valve was ex-hibited—some other task also. There was no sign of any hydraulic equipment onview, and one is led to the conclusion that Firestreak's controls are actuated by pneu-matic rams. If extreme pressure were applied to either side of a paston-type jackthe latter could be held very firmly, thus making the control irreversible. Alternators. Among the range on view(picture, p. 448) was a hydraulically driven unit and the machine associated with theArmstrong Whitworth power pack (q.n.). Also on show was a very neat alternatorunit with an electronic controller at one end, the turbine in the middle and thealternator at the other end. As is generally preferred, the unit was strap-mounted.It was natural that Dowty should be brought into the guided-weapon picture atan early stage, and this is the first time the company have been able to show what theyhave achieved in this challenging field. Their exhibits covered a wide range ofdevices, all carried on board the weapon. One of their hydraulic pumps deliversno less than 2 cu in fluid per second at 3,000 lb/sq in, though it weighs but 12.8 ozand measures less than 2in long; of the fixed-displacement type, it operates at24,000 r.p.m. A much larger pump was de- signed for use in big anti-aircraft weapons.At 8,000 r.p.m. it can deliver 55 cu in/sec at 3,000 lb/sq in, with inlet pressure of10 lb sq/in; the weight is 7i lb andthemini- mum ufe 30 hr at 150 deg C. Anotherrotary machine by Dowty is a hydraulic motor with an output of 6 b.h.p. at 4,000r.p.m. Of the 10-cylinder axial pattern, it takes 3.4 gal/min of oil at 3,500 lb/sq inand has a weight of only 3.5 lb. Dowty makes several varieties of hy-draulic accumulator for missile applica- tions. Both high-pressure and low-pres-sure versions are in production, each type being a simple and efficient piston-typeunit. The h-p. assemblies weigh 10.6 lb and contain (oil plus gas) 311 cu in; thestandard 1-p. bottles weigh 7.09 lb and con- tain 287 cu in. A related device is a "con-stant-pressure" reservoir, which comprises a large-diameter piston loaded through asmaller piston connected to the h-p. cir- cuit, eliminating the need for air or gasinflation. One of the most important Dowty mis-sile accessories is a single-stage servo Two missiles seen at Farnborough for the first time were the Vickers-Arm- strongs Type 888 (Red Dean) and the Short surface-to-air guidance-research vehicle. The 888 rear end is shown at far left, the blunt control trailing-edges being notable; the Short missile has low-speed," wrapped-sheet, pivoting wings arranged in a cruciform.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
