IT WAS ALL THERE, in black and white. The cockpit instruments lacked colour coding, or pastel panels - but then I was going back 30 years. Vickers Viscounts were once flown in British European Airways (BEA) colours over England, the Scottish Highlands and elsewhere in Europe - and between West Germany and Berlin, in parallel with Pan American and Air France services. Berlin always came to the nostrils during the approach - a sulphurous smell of coal-fired central heating in the ventilation ducts over the last few thousand feet. A far cry from sun-swept Essex, and this "yesteryear evaluation". Having just flown the Dornier 328, the latest turboprop, I knew the difference would be striking, but this trip was pure nostalgia.
Airliners with four turboprop engines are almost a thing of the past. For this test, British World Airways provided a Viscount 806, G-APEY, one of the last few passenger examples in the UK - by 1996 all of its fleet will be freighters, or retired. Many former BEA pilots will remember "Echo Yankee". I last flew "EY" into Jersey. Or rather, I did not, for a 40kt (75km/h) crosswind sent us to Guernsey instead. Did it ever forgive me for doubting its ability?
GROUND CHECKS
Capt John MacNiece swung each propeller, checking that the blades were feathered. Much can only be checked externally: hydraulic-pressure accumulators, door-seal pressure, alcohol de-ice contents and heavy-landing inertia-trip switches among them. He glanced up each jet-pipe, checking the six temperature probes and, in the inboard engines, airframe de-icing heat exchanger scoops.
Were the rubber discs of the Maxaret anti-skid system contacting the inner rims of the wheels? Were the freight doors locked, black discs with yellow spots showing in Perspex windows? Was there any damp rubbish in the gap between elevator and tail plane - sealed with a skirt - just waiting to freeze in flight?
The passenger doors are not the modern plug-type: three pairs of heavy claws engage inside the frame to close them, and yellow stripes are displayed to confirm engagement. Securing the locking handle in a stirrup, triggers the inflation of a sealing tube around the door - more basic engineering.
The passenger cabin, lit by big oval windows, seems large even with five-abreast seating. Under-floor hatches give access to batteries, manual temperature control - and to the "ditching lever" for the pressurisation spill valve, which has to be pulled for 20s to shut the valve.
There are many jobs on a Viscount, which take the crew members, out of their seats. On the Viscount 701, for instance, the winding handle for the emergency flaps was in the aisle - much to the passengers' interest. An intercom there kept the captain in touch with his co-pilot's sweaty progress - been there, done that. This time, I also eyed the hydraulics cupboard, on the right cockpit bulkhead - where, in the past, I have topped up the hydraulic reservoir or made emergency selection of the gear.
The cockpit is small, on a slight platform, with close-set windscreens. The rugged seat adjustments are effective. To adjust the rudder pedals, the pilot just edges cogs on a star-wheel round with his shoe - simple, solid engineering. Aah Vickers, Hawker Siddeley and Handley Page - where are you now?
The science of ergonomics had hardly been born when the Viscount was, so systems controls were spread around oddly. Generator switches and gauges are on the co-pilot's side console, while the pressurisation control is behind the captain's elbow and the radar display ahead, shaded by a cowl and invisible to the co-pilot. The flap selector and emergency control are to the left of the power levers.
The Viscount's "central alert", however, was a leader in warning systems. There is a red light ahead of each pilot which flashes when any of nearly 20 similar lights, by each system's controls, lights up - any one pulled out to acknowledge a failure remains red, and the master lights cease to flash. If a master is pulled out, it glows a steady red, to show that warnings are inhibited.
Most starting drills rely on crew co-operation. Engine-start selectors are to the co-pilot's side and the fuel levers on the centre pedestal. Average starting time per engine is 35s. A single lever controls propeller pitch and fuel schedule. The schedule is reduced by a computed amount, in warm conditions, by four small switches and gauges aft of the pedestal. Propeller speed is not shown, and the twin-needle engine-speed gauge wind up wildly as each engine starts up. (When the Viscount is airborne, engine speeds remain at10,400-14,500RPM, and the gauge is easier to read.)
A jointed "butterfly" of brake levers behind the left hand control wheel, can be operated by either hand. A parking catch is turned across to hold the levers together, and aside to release them (it springs back to avoid inadvertent engagement) - straight engineering again.
Moving off from the ramp, I used outer-engine speed to control taxiing speed. The hydro-mechanical nose wheel steering moves the wheel through angles of ±50¡. A rod runs from the half-wheel tiller through the nose-wheel bay, to pick up cables, which run down the nose-leg to the steering jacks. This linkage tends to loosen with use, so that manoeuvring a Viscount on the ground starts to feel like steering an airship.
The locks on the flight-control surfaces spring out when a handle on the centre pedestal is released. With the locks in, the power levers cannot be moved more than one-third open. The control column runs forward under the instrument panel, and a rotating housing allows roll inputs.
STATELY TAKE-OFF
A simple board, and spring clip on the control wheel, held my notes firmly. Take-off reference speeds at 21,500kg (about 8,000kg below maximum), using 43% flap were V1 98kt; Vr 101kt; V2 106kt; flap-retract speed was a mere 10kt above V2. It takes up to 25s for the electric flaps to run between 43% and up. Unless take-off power is fed in carefully, the propeller blades and torque (Tq) delivered surge, as on more recent free-turbine engines.
Acceleration after brake release is stately rather than exciting, quite in keeping with the sight of the classic clockwork "kitchen egg-timer" mounted on the coaming. The gear retracts in 10s - rocker buttons control an electric actuator in the hydraulics cupboard behind the pilots, so its operation is audible. If the gear-down green lights fail, white sight-rods project above the wing and into view through a window in the cockpit floor to give confirmation that everything is in order.
Hot-air airframe de-icing can be used during take-off - a rare refinement. Back in the days of the Berlin corridor, maximum permitted altitude was 10,000ft (3,000m) and, in winter, de-icing was used full time. At times, propeller electric de-icing mats would burn out in a spectacular display, or St Elmo's fire would play around the windscreens - preceding a lightning strike. The hydraulic wind screen wipers are physically unlocked by a lever under the coaming, and the wipe-rate is set by a wide flat knob - as for tuning an old radio - by the pilot's elbow. - a challenge if you want to hurry.
The Viscount is a muscle-wrenching aircraft in all axes. Lift-off had been a real heave, and it banked only after firm pressure had been applied to the control wheel. Using the rudder induces roll very slowly. A 60¡ roll-reversal takes 7s. Dutch roll at any speed is innocuous, but as the rolling is damped, the nose quickly drops, as it does in turns. At 45¡ bank, the stick load was heavy. There is no electrically powered pitch trim here: the trim hand-wheel is powerful, yet sensitive enough to let the pilot set the aircraft to fly accurately hands-off.
Air from two engine-driven compressors is spilled until needed for pressurisation. One spill valve is shut for take-off and the other closed at 8,000ft. There used to be a third compressor, but it was removed when the operating ceiling was reduced (from 28,500ft to 17,500ft) and maximum pressure differential changed from 0.45bar (6.5lb/in2) to 0.24bar, to extend fuselage life.
The fuel gauges and switches are on the right skirt-panel, but can be seen by the captain. Cross-feed from the inner tanks, were timed until the 4,000litre load was balanced - that clockwork timer in front of the co-pilot works.
The VOR/DME controllers are now above the engine panel, where the Decca Navigator Log used to be. When I flew Viscounts, they were on the overhead panel. The Viscount was the first airliner with a moving-map display - a printed paper route rolling under a pen. Signals from Decca chains of three transmitting stations defined intersecting hyperbolic lanes for position fixing.
TIGHT CLIMB
Engine speeds were 13,800RPM for the climb at 180kt indicated airspeed. In the cruise, the IAS settled at 195kt (250kt true airspeed): at 16,000ft in ISA + 15°C conditions, the fuel flows were 340litres/h each, about half the rate at take-off. Cockpit noise is comparable to that of current turboprops, but cabin noise, boosted by the characteristic whine of the Darts, is higher than is now usual in the plane of the propellers. Away from the propellers, noise levels are acceptably low, even in this empty aircraft, and the whole passenger area feels remarkably "tight" for a 36-year-old airliner, despite some trim rattles in the propeller plane.
The Smiths SEP2D autopilot was a leader of its day. VOR tracks and the instrument-landing-system (ILS) localiser, but not an ILS glide-slope, can be captured from a heading. The Viscount 701 had a side-located controller for each pilot, while the 802 series had a single controller and was the first to have a height lock. Failure of the autopilot, is notified by an aural warning, but disengagement is indicated only by an amber light. Altitude "capture" is best made by reducing the climb rate, just before the altitude lock engages and descent by tripping the pitch channel and re-engaging it. The flight director has separate ring-sight-to-pointer displays for pitch and roll. A pitch datum, moved up for climb, is reset down for an ILS approach. The azimuth scale of the horizontal-situation display is selected to track. The radio-magnetic indicator's compass alongside provides better orientation in large turns. In gusty winds, a good technique is to use the autopilot to control heading, while flying manually in pitch.
DESCENT AND STALLS
For descent at idle power, the fuel trim is set to zero. If the fuel heaters are on, the power reduces further. With our light- weight - a 3,000ft/min (15m/s) descent rate was reached at 180kt. Back on the level at 5,000ft, a 235kt IAS was achieved with 14,000RPM, and maximum cruise power, yet fuel flows were still only 450litres/h. The Viscount cruises at low altitudes without great relative fuel penalty (although its consumption is much higher than those of more modern aircraft with newer, electronically controlled, engines).
A simple stall vane under the left wing triggers the stick-shaker and engine auto-ignition, giving an unmistakable warning 8-12kt above the stall speed. We did not fully stall this matronly aircraft, settling for gentle manoeuvres at 20kt above the stall and pulling away from shaker speed in level flight. The stall-warning speeds were 98kt with 68% flap, and 88kt in the landing configuration. The Darts accelerated from flight idle to full power in 7s.
In side-slips the rudder is very firm, so aileron control seems relatively loose. The minimum control speed (Vmc) at 43% flap is 106kt: with the critical number-four engine feathered, the rudder load needed to keep a constant heading is heavy.
HAPPY LANDINGS?
On our first approach to south end, I initiated a go-around from 200ft. I briefly reduced power to idle, to allow MacNiece to select flap to 100%. The flaps retract automatically to 85% as soon as the power levers are moved forward. Although I brought the nose up rapidly, the speed only dropped from 120kt to 106kt. Pitch control is good at all times.
The landing-flap setting adds considerable drag and, in the case of an engine failure, the flaps must be promptly retracted further. A dual-protected propeller-blade flight lock is checked before approach, as the ground-idle angle produces a lot of drag.
The brake gauges outboard on the left skirt-panel, can be seen by the co-pilot at an angle. The position of the anti-skid selector lever, at the right rear of the centre pedestal, is another doubtful ergonomic feature. Our touchdown was smooth, but I made a lousy job of braking and steering, leaving rather more rubber on the runway than had been there before - I say mea culpa, but perhaps Echo Yankee was getting its own back after all these years.
Duly chastened, I closely followed the very narrow taxiway and turned through 90¡ to park outside the British World hangar. The inner engines drive the hydraulic pumps, so the outers were shut down - which both saves fuel and reduces the chance of propeller damage.
TURBINE PIONEER
The Viscounts started a magic age. Even the first 701 could fly at nearly 30,000ft - well above the piston-engined aircraft of the day - or cruise at 300kt. They more than any other aircraft, introduced the public to the smoothness of turbine-powered flight and, with their panoramic oval windows, were extraordinarily popular with passengers for three decades. British World's last few passenger variants are about to disappear, but the fleet will still perform a useful freighting role, in the 5.5-8.5t payload class, where there is little else to replace them, for several years to come.
It was a pleasure to renew my acquaintance with an old friend, and I thank British World for having made it possible.
Source: Flight International
