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Aviation History
1963
1963 - 1342.PDF
166 FLIGHT International, I August 1%$ WESTLAND WESSEX 1 in the Air... can be trimmed into a turn by displacing the cyclic stick, or it can be turned hands-on" by pressing on the appropriate rudder pedal, foot pressure releasing the heading lock. This results first in a yaw and then in a co-ordinated turn. As soon as the rudder pedal pressure is released, the heading lock returns to hold the new course. Barometric or radar altimeter height can then be engaged as required, using a height selector dial, and an automatic transition and hover can be selected and performed entirely hands-off. Doppler rate of change of height signals are fed to the autopilot. The Wessex will descend, stop and hover automatically, and station-keeping can then be related to Sonar cable angle and ball depth. It is possible to hover with the autostabilizer alone, care fully setting the cyclic stick to produce the necessary attitude without positive ground-sensing—and subject to wind shifts and similar factors. Because all this involves the use of a master reference gyro, the main artificial horizon is a remote indicator and can be set in a sloping instrument panel, which is easy to watch. There is a stand-by artificial horizon* and a Doppler cross-pointer indicator to show horizontal movement during translation and hover. Displacement of the needles indicates the rate and direction of machine providing very good damping. Changes of speed were very easy, but a fair amount of rudder was needed to compensate for speed and power changes. Approach at 60kt and transition were quite simple, though I asked for the forceless mode to be selected. Somehow, with the low stability of the helicopter, a forceless control is much more comfortable during considerable attitude changes than the fairly firm stick-centring one would expect in a fixed-wing type. I also allowed for increased inertia by losing speed earlier and made sure that the tail was well clear of the ground. A touch of twist- grip kept the rotor governor in step. With these factors in mind, the transition was completely straightforward, and the almost violent vibration peak of the piston-engined S-58 as it came to the hover, was replaced by a barely noticeable shake in the Wessex. At the hover, in a few turns and patterns, the aircraft was very pleasant. The hydraulic damper in the rudder circuit was quite noticeable during turns, but had a welcome smoothing rather than a restricting effect on control. Touch-down and take-off required no special control movements—the Wessex sat down like a lady and got up like a gentleman. Having flown the machine briefly in its various modes and appreciated the helpfulness of the autostabilizer in reducing the pilot's work-load, I was the more impressed to observe the fully The sloping grey panel of the Wessex HAS.I, left, carries the globe horizon of the -IN system, together with barometric, radar and Sonar-cable height indicators, all duplicated for the two pilots. Engine instruments and controls are on the centre panel and console The -IN system allows the Wessex to hover in relation to the extension and angle of the Sonar-ball cable, shown extended at right translational movement. When the needles are within a specified distance from centre, the Sonar ball can be lowered into the water. The Wessex is cleared for a maximum 120kt at sea level—a speed not limited by blade-stall—and maximum power "pulled" with collective lever is 4481b on the torque gauge. Flying at a weight of about 11,5001b—gross weight is 12,6001b—some 4001b torque gave l,000ft/min in a vertical, spiralling climb, representing an excellent power margin. Having derived this information in a quick briefing from West- land pilot Ron Crayton I made the long climb up to the left-hand (co-pilot's) seat. You can start with either foot and there are plenty of hand-holds. (I remember amusing stories of starting with the wrong foot to get to the front cockpit of the Gannet and ending up in the rear cockpit instead!) A pale grey instrument panel makes a pleasant decor, but it is a little surprising to find that one's seat is suspended over the heads of the foremost passengers, there being no cockpit floor aft of the foot-space. Crayton handed over control in cruising flight and we began to go through the various control modes. I noticed that when rudder ing in autostabilizer or changing automatic modes, the Wessex sometimes gave a sharp kick side-ways, particularly when nailed to a heading after a fairly pronounced turn. Flown non-automatic- ally, it was very pleasant, the considerable inertia of so large a automatic transition from cruise at several hundred feet to a sta tionary hover at a pre-selected 30ft. This manoeuvre requires a degree of training for a human pilot flying manually in poor weather and may involve difficult attitude changes, but the autopilot seemed to produce a perfectly blended transition and remained well locked to the spot under Doppler control. The "unlocked," Pure,y autostabilized hover Crayton next selected was noticeably less firm- Such a degree of automation is, of course, highly desirable when the helicopter may have to spend half an afternoon, or night, at the hover with its Sonar ball in the water. The strain of hand-flying in poor weather would be excessive. In this context, the smoothness and quietness of the turbine must also be extremely important advantages. The final degree of comfort would come with the twin- engines of the Wessex 2, though the Navy will not have such a variant until the Wessex 5. ... The Kaman Sea Sprite laid claim at Paris to exceptional high speed capability, but Westland's chief test pilot "Slim" Sear th;>ugnl the Wessex had its measure after they had spent some days going round the helicopter circuit together. He was ready to challenge we Kaman pilot that if he flew the Sea Sprite level in any way he liken. the Wessex would catch him. It certainly has performance, as weu as an effective flight control and anti-submarine system, turbffl smoothness and many additional capabilities.
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