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Aviation History
1983
1983 - 0062.PDF
PIK-23 LEADING DATA Dimensions & Weights Wingspan 32 8ft, 10m; length 23 6ft. 7 2m; height 9 5ft, 2 9m; cabin width 3 7ft, 1 09m; propeller ground clearance 1 -2ft, 036m; empty equipped weight 1,3001b, 590kg; max take-off weight 1,9181b, 870kg. Manufacturer's performance figures Cruise (65 per cent power, 12,000ft, 3,660m) 11 9kt, 220m/hr; range (same conditions) 675 n.m., 1,250km; endurance 75 per cent power, 5hr; sea-level climb rate 1,150 ft/min, 5'8m/sec; climb rate with single-seat glider 750ft/min, 3 8m/sec; take-off distance (to 50ft, 15m) 1,050ft, 320m; landing run 490ft, 150m. Prototype manufacturer Valmet Corporation, Kuorevesi Works, SF-35600, Halli, Finland, telephone 358-42-8291, telex 28269 valku sf. be good; effective flaps with a high limit speed allowing a steep descent and approach should be provided; the engine installation, preferably with cowl flaps, should withstand constant cycles of slow, full-power climbs and rapid descents; and, above all, it must be tough. The Tow- master's designers have clearly tailored it for the job, and have come up with a bonus, since it is an attractive light aero plane on many other counts. In side view the Towmaster shows some kinship with Valmet's L-70 trainer, its fuselage having similar overall propor tions. But the rear fuselage is slimmer, without the latter's long dorsal strake, and close at hand it is evidently a very different aeroplane. Both fuselage and wing have a glassfibre/epoxy/PVC foam sandwich structure, the wing merging with the fuse lage via a big wing-root fairing. Spar caps in the two-piece wing are of carbonfibre. Both rudder and elevator have biggish horn balances, the elevator having a trim tab on one side, which is electrically pow ered on the prototype, apparently for sim plicity. A tank in each wing gives a com bined capacity of 44 Imp gal—good enough for 5hr at 75 per cent power. The glider release hook is an integral part of the tail, so that you simply "plug" a towrope into the back of the aeroplane rather than hook it on to an external rig as with many other tugs. Ailerons are of the Frise type, mass- balanced and with differential action, and produce negligible adverse yaw in the air. Mainwheel legs are of carbonfibre- reinforced plastic, and have replaced the straight units first seen on the aircraft. There are two large, adjustable cowl flaps for the 180 h.p. Lycoming and its Hoff mann propeller. The Towmaster stands fairly high off the ground, and climbing on to the wing is a high-stepping business. A high seating position and that big one-piece sliding canopy promise marvellous all-round vis ibility, with the sills well below shoulder height and the average person looking down on the panel and engine cowl, rather than at them in the American style. The panel layout is neat and un cluttered, but on the prototype at the time of our flight there were inevitably some A large wingroot fairing carries the wing walkway; flaps are fully down here COMPARATIVE DATA AND PERFORMANCE Piper Super Cub Power h.p. Empty weight (lb) Max fuel (Imp gal) Max weight (lb) Max power loading (Ib/h.p.) Max climb rate (ft/min) Take-off distance (ft) Landing distance (ft) 150 983 30 1,750 11.6 960 500 885 Rallye Galerien 180 1,200 40-5 2,094 117 870 1,340 1,120 Robin DR400/18OR 180 1,234 22 2,205 12 25 825 1,313 1,542 Valmet Pik-23 180 1,300 44 1,918 10 6 1,150 1,050 1.000 "oddities" which will be altered on sub sequent aircraft. The ignition switch will probably move from its position on the far left into the centre, the single throttle will be duplicated, and the tow release may move to the far left, near the left-hand throttle. The central flap lever will stay where it is, and the electric trim, if not replaced, will presumably have to be at least duplicated by a manual trim wheel or lever for certification. A deep panel evidently has plenty of available space, and on production aircraft The recessed towhook is unusual for glider tugs 82 the radio stack on the far right would probably be transposed with the large panel of engine and fuel instruments. The Towmaster is currently well-instrumented in this respect, with CHT, EGT, and car burettor temperature gauges to monitor engine performance. Engine vibration and noise seem well- damped in the composite structure, and as we taxied out the superb visibility on the ground was immediately impressive, yards of runway being visible in front. This is an asset on a gliding site, where tyres and other objects tend to get left in odd places. The nosewheel is steered via spring rather than direct linkage and its action is one of the softest and smoothest I've encoun tered. The Towmaster made light work of take-off from a hard runway. The elevator, sitting directly behind the propeller wash, came alive very quickly on the run and, after an effortless rotation at 45-50kt, we climbed like the proverbial cat at 65kt and full throttle (2,600 r.p.m.). Two-up, and with half fuel, we averaged l,300ft/min to 3,000ft in ISA +5°. Despite the steep attitude without a glider on tow behind, visibility was still good, aided by the high eye-line and the rounded nosecowl shape which falls away to either side. An authoritative response in all axes looked as if it should cope well with an argumentative glider, with light rudder forces. At the top of the climb CHT peaked at 350° (maximum 430°-500°). FLIGHT International, 8 January 1983
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