Flying Machines 6: The Vanguard

The airliners get a bit more detail and a page each. The first big aeroplane I flew was the Vickers VC9 Vanguard which had originally been bought by BEA, which became part of BA. I flew them when they were sold to Air Bridge Carries (ABC) in the early 1980s.

A BEA Vanguard 953 taking off. This would be the first livery it was painted in. It shows the very large slotted flaps well.

A BEA Vanguard 953 taking off. This would be the first livery it was painted in.
It shows the very large slotted flaps well.

The Vanguard grew out of the Vickers Viscount which had been very successful aeroplane for BEA, but by the early 1960s was getting a bit small. BEA had asked Vickers for a stretched model, but it quickly became obvious that the new Rolls Royce Tyne engine with nearly two and a half times the power of the Dart that powered the Viscount was the obvious choice of engine and that led to a much bigger aircraft. More than twice as big. It was also much faster with a typical cruise speed of just under 350 knots. It was one of the fastest turbo-props ever built with only the Tu 114 being very much faster.

The fuselage was wide enough at deck level for six abreast seating. The fuselage was made bigger still by making it a “double-bubble” or figure of eight shape that allowed very large cargo holds. This fuselage shape and cross section was also used in the jet VC10 that came later. The first six aircraft that went to BEA were 951s. Air Canada had ordered an aircraft with higher weights, 5,500 hp engines and a Collins flight system which was designated 952. The BEA order was completed with 953’s which had the stronger airframe, but the same engines as the 951 and the same bizarre Smiths flight system and the much more complicated overhead panel.

The flying controls were all manual, although they all had fairly powerful spring tabs to ease the load. This was on an aircraft with a maximum weight just short of 70 tonnes and a maximum speed not far short of 400 knots. The only power assistance of any kind on the flying controls was a electric motor that could move the rudder trimmer quickly after an engine failure. The wing loading was also very high, certainly much the same as modern jets giving speeds on the approach of around 130 knots. Flapless approach speed was 165knots. It had massive slotted flaps.

The Mighty Tynes at take-off power. This appears to be at Belfast on a damp day and you can see the moisture trails from the prop tips. You are looking at 10,000 hp in this pic! With 15,250 RPM in the LP turbine the 14ft dia props turned at 950 RPM

The Mighty Tynes at take-off power. This appears to be at Belfast on a damp day and you can see the moisture trails from the prop tips. You are looking at 10,000 hp in this pic! With 15,250 RPM in the LP turbine the 14ft dia props turned at 950 RPM

The 5000 hp “Mighty Tynes” meant it was quite overpowered for its time and it had an unbelievable amount of reverse thrust. The reverse thrust was very rarely used in service with “Ground Idle” being quite enough to slow the aircraft. If full reverse was used with maximum wheel braking it was quite possible to get a stop of over 1 G with everything not nailed down ending up in the cockpit.

The engine was said to be “Single lever control”, but this didn’t stop there being 16 engine control levers in the cockpit (four throttles for the Captain, another four for the First Officer, four HP cock levers that combined the functions of HP cock, fuel trimmer and feathering lever and four levers that put the engines into low ground idle for starting. The propeller had, as far as I can remember, seven different pitch stops. From memory, the coarse pitch (feather) stop, the overspeed stop, the flight fine pitch stop, the reverse stop, the beta follow-up stop and two I can’t remember. On the tech course we were told that when new only God and De Havilland knew how they worked, but it was suspected that the Almighty was now the sole possessor of that knowledge.

Don’t read this paragraph unless you are really interested in how the engines were controlled. The engine control system was complex. In the flight range the throttle lever controlled both engine power through the fuel control unit and propeller RPM through the propeller control unit (PCU). Since the propeller was geared to the LP section by a 16:1 reduction gear it also controlled LP RPM. In the ground range (Beta Range) everything was reversed; the lever controlled raw prop blade angle directly and RPM was controlled by the fuel control unit. Thus the engine at ground idle and zero thrust (when the A/C was stationary) turned at about 12,000 RPM if you moved the levers forward thrust increased, but RPM reduced to about 10,500 at the flight idle gate. As the throttle moved further forward the power increased as did the prop RPM to reach full power at 15,250 RPM. Maximum continuous power was 13,500 and climb/cruise power was 12,500 RPM.

Since the temperature, and therefore density, of the air entering the engine will alter the amount of fuel that can be consumed the single lever could only be correct at ISA (altitude was corrected automatically) and to avoid overtemping the engine at higher air temperatures, there was a fuel trimmer lever that reduced the amount of fuel at any power setting. This was combined in one lever that also controlled the HP cock and controlled feathering of the prop. From the most rearward position the detents were Feather, HP Closed and HP open. Further forward movement went into the fuel trim range with a setting scale. The correct fuel trim was calculated from a table in the check list.

The Vanguard Cockpit Engine instruments on the centre panel and the pilot's flying instruments on either side.

The Vanguard Cockpit
Engine instruments on the centre panel and the pilot’s flying instruments on either side.

The cockpit was typical of the era when they got as complicated as they could before automation started simplifying the layout. BEA had not helped by insisting that pilots were given control of systems that they didn’t need to. The electrical system in particular suffered very much from the state of the art at the time. Electrical power was generated by four (originally six) 50 Kva alternators producing frequency wild AC (that is frequency varied with engine LP RPM). Since almost all the aircraft systems were still 28 volt DC, the ac power was fed to three 700 amp, 28 volt transformer rectifiers. This is big power! The engines had electric starters that could (and did) stall ground power units. It needed well over 2000 amps to start.

The engine instrument panel is in the centre and the pilot’s flying instrument panels either side. The engine instruments from top to bottom are:

Low Pressure RPM, Torque, Turbine Gas Temperature (TGT), combine oil pressure and temperature gauge, Fuel flowmeter. Dotted around among them are various warning lights for Flight Idle gate open, Propeller below flight fine pitch, Auto Drag Limit System (ADLS) working (i.e. the prop had automatically feathered), low oil pressure and high oil temperature. If you are wondering where the HP RPM gauges are, you can just see them down by where the First Officer’s right knee would be.

Above the engine instruments are the Fire Control Handles with the red fire warning lights in them. If you pulled the handle out it shut off hydraulics, armed the LP cock to close when the prop was feathered and several other things I have forgotten. If you twisted the handle it fired the fire extinguisher into the engine.

If you are wondering what the wheel is on either side if the cockpit outboard of everything else, it is the nosewheel steering control.

The orange lever behind the left hand throttles is the flight idle gate that Vickers called the “Alpha/Beta arming lever” the purpose of which was to drop a plate behind the throttles as they moved forward through the gate and prevent them moving back into the ground range which would be very hazardous in the air. In addition to this each of the eight throttles had a latch near the top that also prevented movement below flight idle; only one of these latches needed to be released to allow all throttles back through the gate.

The flying controls were all manual with no power assistance. As you may image the control surfaces were very big and some assistance was given by spring tabs, a sort of trim tab, but connected into the control circuit. The controls were locked with mechanical locks at all time on the ground and only unlocked (with the big lever to the right of the First Officer’s throttles) when the aircraft was lined up for take-off. Reputedly a BEA First Officer suffered a broken leg when the rudder was unlocked in a crosswind. On landing the controls were locked again at 80 knots otherwise they would thrash around in the prop wash.

The three grey buttons towards the rear of the pedestal were the Autopilot Gearing Rundown buttons. They were used during an ILS approach flown by the autopilot the idea being to reduce the sensitivity of the autopilot to ILS signals as it got nearer the ground. Since there were no radio altimeters to give the avionics any height information it was achieved by timing after you pressed one of the buttons as you passed 1500 ft. This, of course, depended on the headwind and airspeed which would alter the groundspeed, but we couldn’t measure groundspeed either. The answer was to check the rate of descent at 1500 ft and press one of the buttons. The middle was labeled 700fpm and the others something higher or lower as appropriate. In practice I only ever remember using them if the Chief Pilot was on board. In case you run away with the thought that it controlled some clever electronics, all it did was set a clockwork (yes, clockwork) motor going at the appropriate speed.

There were various attempts at syncrophasing the propellers, that is not only synchronising the speed, but also making sure that the blades of two adjacent props were kept 45 degrees apart to reduce noise and vibration. The idea was good, but alas the mechanical control of the props was just not up to it and things continued to rattle and roll around for the life of the aircraft. The electronic system on the Dash 7 of 20 years later did the job much better.

After a relatively short life in passenger service they were largely converted into freight aircraft by adding a large freight door on the front left side of the fuselage, blanking all the windows and putting a roller mat and pallet handling system in the floor.

More to come