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Aviation History
1950
1950 - 1990.PDF
1 23 November J950 The cockpit and nose-profile changes aside, and with one or two detail exceptions, the Trainer can be regarded as a two-seat Vampire 5. It has the same wings and booms as the 5, but has a Goblin 3 power unit which differs from standard Vampire practice only in that the pressure for the cabin is tapped from the engine compressor instead of being supplied by a separate cabin supercharger: the differential is 2.751b/sq in. There are also slight deviations in the tail surfaces, made necessary by virtue of the extended nose and, by the same token, these changes apply also to the D.H. 113 night fighter. They are as follows: the elevator trim tab has been increased in span (although the chord remains the same) to provide nearly 50 per cent greater area, the rudders have both been heightened so that they are of greater aspect ratio, whilst the tailplane tips have been extended so that they now project outboard of the fins. The increased nose area and the eg. shift relative to the Vampire 5 make it understandable that some com- pensation would be necessary in the tail surfaces to counter- act the consequent influences on directional and longitudinal stability. In the night fighter, the nose compartment, of course, houses the radar equipment, but in the Trainer •-•• this stowage volume is given over to radio, batteries, oxygen bottles and, in the extreme nose, a G.45 cine-gun camera: in the prototype, two four-channel V.H.F. sets are installed, ^ but these are likely to be supplanted by a single ten- channel set in production aircraft With a cockpit which, at shoulder level, is 44in wide— Le^ an inch wider than that of the Airspeed Oxford, and 6in wider than that of the Mosquito—an entirely new form of canopy had to be devised. The framework is of welded tube, with glazing flats welded on, and on each side of the large, single-piece optically correct front screen are flanking direct-vision panels. The front screen is a four- ply Triplex unit, the two inner, fin-thick panels of which are fronted and backed by tVin-thick panels, all four being sandwiched with Vinal interlayers. In common with the remainder of the canopy, the direct-vision panels are glazed in Perspex, and are of a rearward-sliding type similar to those used on the Ambassador. Access to the cockpit is provided through the roof panel, which, hinged at the rear centre-point, is locked by a pair of turnbuttons on each side, actuated from an internal lever mounted in the centre of the upper front-screen rail. A flush-retracting handle in the fairing at the rear of the hood is tied-in to the turnbutton linkage so that the hood can be opened from outside. For emergency jettison, a small hydraulic jack is embodied inside the hood, and connects into the external release-handle linkage to the turnbuttons. The jack is quite small, but is, nevertheless, amply sufficient to release the hood in flight—a job which, due to the increased friction on the turnbuttons as a result of the air load on the hood, might be beyond the power of a man's wrists even in the compelling circumstances of an emergency. Upon release, the leading-edge of the hood lifts somewhat, and when being jettisoned would be whipped back by air pressure and so break a shear point in the hinge. In relation to the very short time taken to produce the prototype, the excellence of the Vampire Trainer's cockpit * layout is most marked., We have seen all too many cockpits that |iave been the refult of months of deliberation, but, evpn so, have still beeij mediocre. The Trainer, however, has a cockpit which actually looks inviting; it is admirably " laid out, uncluttered and—perhaps the secret of its success —is absolutely straightforward. The seats are standard "•"* 25/40 g S.B.A.C. buckets, the centre of the pupil's seat Ij being offset lOin to port of the fuselage centre-line, whilst that of the instructor's seat is offset llin to starboard, this asymmetry—which is completely unobtrusive—being neces- sitated by the pupil's throttle-box and the elevator quadrant —w»«n the port side. Both seats are carried on horn-arms off ^ lateral torque-tubes supported in extruded pillars, each seat being individually adjustable by a handle on the right-hand horn-arm, and located fore-and-aft by a pair of radius struts off the rear bulkhead. Behind and between the seats is a built-up box pillar carrying wing-tank jettison control, ground/flight master switch control, cabin pressurization control, and cabin temperature control. The alligator nose offers magnificent accessibility. ... > ./•••• • - - Q , Wrist-action control columns are fitted. Instead of the spade-type grip used in the ordinary \Vampire, the latest Dunlop moulded grip is used, and ah^xtraordinarfly neat and comfortable unit it is. The brake lever curves upward and outward from the base of the grip proper, and in the head of the grip are press-button and trigger-type switches for camera, guns, and bombs; R.P.S are fired by the gun button, after individual selection on a separate switch. For dual-control purposes, the control columns are linked by push/pull tubes to a bridging cross-tube behind the dome of the nosewheel well, which projects about 7in above floor level and runs back into the cockpit roughly to the front of the seats. Universal shafts extending rearward from the base of the columns carry sprockets for cross-linkage chains, and the port tube also carries cable anchor wheels from which the aileron cables run out to port, round Tufnol fairlead pulleys, and so, together with the elevator and rudder cables, rearward through a cast gland-box for pressure retention. Rudder pedals of standard Vampire-Mosquito-Hornet type are hung from a pair of torque tubes bridging the cockpit, and although four feet have to be catered for, the spacing of the pedals is not too constricted. The pedal centres are, in fact, of the order of 14in, and pilots who fly the Trainer from either seat should be quite com- fortable. Interconnection of the engine, elevator trim and dive- brake controls is rather complex. The throttle, high- pressure and low-pressure cocks and the elevator trim control have an endless Teleflex system running back from the pupil's throttle-box to Teleflex pressure joints on the rear pressure bulkhead. Off one side of the throttle and elevator trim circuits, insert sections are taken in cable and Detail of hood-locking system. The jack is purely for hood-jettison in an emergency when manual strength might be insufficient.
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