by Mike Brooke
The scientists had already produced two systems that had potential for giving aircrew those better eyes. One was Low Light Television (LLTV) and the other was Forward-Looking Infrared (FLIR). There were also prototype Night Vision Goggles (NVGs) that used the same technology as the LLTV to enhance the night light levels to a useable amount; however, in 1976 NVGs were in their infancy and definitely not suitable for fast-jet pilots to use. Because of the cooling requirements and the state of electronics in the FLIR systems of the mid 1970s that kit was not ready to be installed in small fast jets either; however, FLIR was being trialled in larger aircraft where there was more space for all the gismos. But more on that later.
At Farnborough there was a very special two-seat Hunter T7 – military registration WV 383 – known as ‘Hecaté’. This name was painted on the side of the nose and is that of the ancient Greek goddess of, among other things, the moon and the sky. Images of Hecaté show her carrying torches, indicating her ability to see in the dark. WV 383 had been used as a trials aircraft at Farnborough for many years before I first got my hands on her. Much of the R&D for HUDs had been done in 383, especially for the cancelled TSR2. Hecaté still had two HUDs in front of the pilots and the one on the right-hand side was still being used for the continued exploration of different types of symbols, the layout of the visual presentation and other esoteric research aimed at optimising the operational utility and safety of HUDs.
But the other obvious item was that the right-hand instrument panel had been replaced with a small TV screen and, in order to give the right-seat occupant the best view of this screen, the top 3 or 4in of the right-hand control stick had been sawn off! The TV screen was there to display the picture seen by the LLTV camera mounted in the nose of the Hunter. That picture was also overlaid with essential flight information such as speed, height and heading. So the job of the pilot sitting in the starboard seat was to try to fly the aircraft in the dark at a selected low altitude and speed, along a pre-planned route and avoid hitting the ground or any obstacles. The man in the other seat was there to taxi the aircraft out, get it airborne and land it (the wheelbrakes were not operable from the right-hand seat). Once settled down en-route the ‘safety’ pilot would hand over to the assessing pilot to fly the majority of the sortie, most of which would be at low level. The safety pilot would then monitor (ever so closely) where the aircraft was going and be ready at any time to take over and climb to a safe altitude. The real irony was that the best information as to what was really going on outside could only be gained by looking at the TV screen! Most of the time it was too scary to look out of the cockpit windows because all you could see were vague, dark shapes and odd lights flashing past below.
I first flew Hecaté in the dark on Wednesday 17 March 1976. Harry Maclean and I were briefed to fly two identical sorties on a route from Farnborough to the West Country and back. On the first flight I would occupy the left seat as ‘Safety Pilot’ and Harry would fly as the assessing pilot. Then we would reverse roles for the second sortie; this would give the scientists two opinions, one of them from a newcomer to this dark art. The minimum altitude at that time was 500ft above ground level at a cruising speed of 360kt. The final aim of the trial programme was to work down to 250ft and speed up to 420kt.
Having flown the Canberra in the dark a few times the previous month I was deemed to be ‘Night Current’ so I flew the Hunter at 2,000ft until we passed into an area of the UK’s Low Flying System about 15 miles west of Boscombe Down. Then I handed control to Harry and he got his head down on the TV screen and descended to low level. I kept a good eye on the height, speed and our position relative to the planned track over the ground. I could tell that Harry had done this before; although concentrating hard he was talking smoothly into the voice recorder when needed and didn’t appear at all stressed. Things were a bit different on my side of the cockpit. The light levels were on the marginal side for the magic kit to operate at its best and completely unuseable by my own visual system. It was as black as the ace of spades outside and my uneasiness was only exacerbated by the illuminated bits of the countryside flashing by beneath us feeling far too close for comfort! At one point Harry exclaimed – I thought that I would need to take over and climb – but it was a momentary ‘blindness’ caused by the headlights of a car coming over a rise in front of us. Bright lights like that caused a large, bright flare on the screen that could temporarily take out most of the visual cues that were helping Harry avoid the ground.
Other than that the trip went well and I had now seen the route and some of the problems that had to be overcome. An hour or so later it was my turn. I settled into the right-hand seat and let Harry take us to the start point of the low-level route. During that short transit I had watched the small screen and familiarised myself with the presentation of the flight information symbology. At the appointed juncture I heard, ‘You have control,’ so I grasped the top of the rather odd, stubby stick and started a gentle descent to 500ft on the radio altimeter. As I levelled off and concentrated on getting the speed right, holding the altitude and trying to follow the route, a strange feeling came over me. I vocalised this for the benefit of the boffins who would listen to the voice recording after the flight.
‘I have a peculiar internal conflict going on in my head,’ I said. ‘One part of me is saying “this is a simulator that I’m flying by looking at a TV screen” and the other is screaming, “no it isn’t – the ground out there is real!! Get a grip!!”’
After a few minutes this internal tension diminished and I started to become accustomed to this rather odd form of flying and navigating in the dark. Then I came to a corner. When I banked and started to turn in the required direction for the next leg of the route the view ahead, in the direction of the turn, shrank to very little. The horizon was now laid at 45° across the screen and a spot on the ground was coming into view only briefly before we were over it. The dangers of turning towards rising ground became very obvious. Fortunately the route had been surveyed and we could compensate for this by climbing a little, even though we would only see what we were climbing over for a few seconds beforehand. The rest of the trip went well and by the end of the thirty minutes I had flown at low level I was feeling much more comfortable.
I would spend many more hours in ‘Hecaté’ helping the A Flight guys with their LLTV R&D. Some would be memorable. Such as the night when I flew with John Bishop while he carried out a landing at Boscombe Down with no runway lighting; in fact no airfield lights on at all. The Air Traffic Controllers took some persuading to turn everything off, but they did in the end. Of course the last bit was the hardest bit. The LLTV gave a very good view but its position in the nose well ahead and below the pilot’s normal eyeline required a bit of interpretation. But JB did a good job and we touched down in an acceptable manner not far from where we should have. We are pretty sure that this was the first ever, lights out, safe, night landing made by a UK fast-jet aircraft.
As we went into the summer of 1976, which became famous for its very long heat wave and drought, a new route was devised for the LLTV trials. This was done to explore another potential limitation that was similar to what we had found when turning. It was this: if the hills and valleys were bigger and deeper than those in the south-west of England then the pilot’s forward view of the top of the next piece of rising ground was limited by the field of view of the camera and the size of the screen. Descending across a wide, deep valley all that you could see was the opposite hillside unnervingly rushing towards you, leading to a strong temptation to raise the nose so that you could see the ridgeline and a bit of sky. This of course would bring the aircraft away from the ground and so lose the advantages of flying at low level. To achieve the necessary topography the new route was in Wales. After it had been devised and planned we first flew it by day with a filter over the camera lens so that we could assess the utility of the route before we tried it in the dark. We could also make changes if we found that the route was either too chal
lenging or not demanding enough. But there was a knock-on effect that became a limitation in itself. To be able to fly to Wales, travel round the route and return, predominately at low level, we needed more fuel than for the Devonian routes. So we had to put four fuel tanks on the Hunter’s wings, in lieu of the two that ‘Hecaté’ normally carried. However, during the hottest days of that golden summer of ’76 the jet was too heavy to get safely airborne from Farnborough’s runway! So then we had to leave the outboard tanks empty and cut the route short! Irony rules – OK?
Thankfully, most of the time we could get airborne safely with the fuel load necessary to fly the full route. On 28 and 29 June 1976 I flew four consecutive sorties in WV 383 once in the right-hand seat and the other three as ‘safety pilot’ to Vic Lockwood. On the last of these the overlaid symbology on the TV screen stopped working but we decided that, as it was daylight and that I had a good view of what was going on, Vic would continue to fly using the screen and I would monitor our height. However, at one point Vic started descending as we came over a wooded hillside in one of the many Forestry Commission areas in Wales. After a few seconds I invited him to ease up. He did so. What had happened was that we had flown over a ‘nursery’ area for new conifers that were only a few feet high. Vic had inadvertently interpreted these mini firs as trees of a normal height and instinctively descended to get closer and make them appear 50ft tall! In fact this was a very useful outcome as it emphasised that a display of height above the ground was essential and that then became a ‘no-go’ item.
The LLTV research programme developed further during the late 1970s. The acquisition and implementation of a HUD that could show both the flight-related symbols and the TV picture20 meant that we no longer had to fly around in the dark looking at a screen just above our knees, a very unnatural posture, but we could rather sit back in the seat and look straight ahead. A much nicer arrangement, although giving the safety pilot a means of independently seeing what was really going on outdoors would have to wait!
Note
20 Such HUD technology was known as ‘raster/cursive’ and became very important for future developments in the display of FLIR.
16 VARSITIES
In early July 1976 we were sweltering under the unrelenting sun of that record-breaking summer. At home we were sharing bath water and throwing the washing-up water on our garden. And still no sign of rain. Then ‘the boss’ called me into the sauna cunningly disguised as his office.
‘Good news. I’ve been told that the flight’s establishment of aircraft is going to increase by three.’
‘Great,’ I prematurely responded, ‘what are we getting – Jaguars, Harriers, Lightnings?’
‘No, Varsities,’ he said.
A stunned silence followed, which he interrupted with a grin. ‘And the really good news is that you are going to be our Varsity specialist. As you are now RAE Farnborough’s Canberra guru and the Varsity is really a Canberra with propellers it’ll be right up your street.’ Although, with my 2,000+ hours on English Electric’s jet bomber, I had to agree with his logic but I hadn’t seen myself as an expert on 1940s piston-engined, twin-prop trainers! While this ‘good’ news was sinking in I was told that arrangements had been made for me to go to Pershore in Worcestershire, where the Radar Research Squadron was based, and where there was a Varsity ready for me to learn to fly. That happened on two very busy days in the middle of July. As is so often the way in the R&D world I wouldn’t actually fly a Varsity again until the following February!
So what is a Varsity? In 1948 the Air Ministry issued a requirement to the UK aircraft industry to propose a twin-engined pilot and navigation trainer as a replacement for the Vickers Wellington T Mk 10 and the Vickers Valetta. Perhaps, therefore, it was no surprise that the Vickers Aircraft Company came up with the winning submission. The Varsity was a development of the military Valetta and the civilian Viking that they had already built and were successfully in service. The main differences were that the Varsity had a tricycle undercarriage, rather than a tailwheel layout, with a wheel under the nose. Moreover, the company had added a ventral pannier under the already rather rotund fuselage; this lower protuberance housed a small, glazed, prone position cabin for a student bomb-aimer and his instructor and, behind that, a bomb bay that could carry up to a couple of dozen 25lb practice bombs. There were hydraulically operated bomb doors over this part.
The Varsity was bigger than a Canberra at about 68ft long, with a wingspan of around 95ft and the top of its tail reached 24ft into the air. It was equipped with two big, round Bristol ‘Hercules’ 14-cylinder radial engines, each driving four-bladed, variable pitch propellers giving a total motive power of almost 4,000hp. That was sufficient to take its 15-ton weight to a maximum speed of around 200kt in level flight and up to an altitude of over 25,000ft. We, however, would be generally operating below 10,000ft and cruising at 130–160kt. The overall impression of the Vickers Varsity was one of bulk. In RAF service it had picked up the rather rude sobriquet ‘the Pig’.
The entry and exit for all who would sail in her was via a ladder, carried on board, let down from the door aft of the wing on the port side. The flight crew, usually of a pilot and navigator for our trials, or two pilots and a nav for training sorties, would then make their way forward to the bit with forward-facing windows, where there was a rearward-facing navigator’s station behind the two pilots’ seats. The instrument panels were pretty conventional for the era and the central console had a wondrous collection of levers that were there to control the engines: rpm, throttles and fuel cocks. The flying controls were manually operated from a control yoke and rudder pedals and the usual set of three trim-wheels fell easily to hand.
Starting the engines was a challenging procedure because one needed more hands and fingers than the good Lord had provided. As well as operating the throttles there were switches on the roof panel to manipulate in a set sequence. After turning the engines over without fuel and ignition on (to ensure that any oil pooled in the lower cylinders was first expelled), the ignition switches were selected ‘ON’ and the booster coil, for that added electrical oomph, was pressed. This usually resulted in a wonderful sequence of pops and bangs, accompanied by clouds of white smoke from the engine’s exhaust, before the Hercules finally settled into a rhythmic rumble. For those of us with little or no experience of big, round motors (and actually that was all of the C Flight test pilots) it was to be an extraordinary experience getting to grips with our new steeds.
Eventually all three Varsities arrived at Farnborough from the various places where they had been operated by civilian contractors; I never did discover the politics behind the move of them back under direct RAE control and finance. That was well above my pay grade! The three were WL 679, WL 635 and WJ 893. The first two were equipped with two different Forward Looking Infrared (FLIR) systems and the latter was employed on highly classified trials connected to the development of Polaris missile guidance systems. We also regularly ‘borrowed’ RRS’s Varsity, WF 379, for training purposes. Once I had converted all of our pilots to type I flew 679 most often.
But why the Varsity? The Varsity was of sufficient size and, although being phased out of RAF service to be replaced by the Jetstream turboprop, it had an adequate performance for the job and was still relatively cost-effective. Its design made it rugged and had given it a very long and sustainable fatigue life. In the early days of the infrared research, using WL 679 as an FLIR trials vehicle, we aircrew just flew the kit and its attendant boffins around the sky while they gathered lots of data on objects and landscapes while playing around with the various settings that controlled the FLIR. Of course it was much more scientific than that, involving esoteric language and technical terms describing the characteristics of the system and its capabilities. The relatively early system in the Varsity was capable of seeing through light mists and thin clouds, but anything that blocked light in the 8–12 micron wavelength could prevent images being identifiable. The detector was a rotat
ing scanner and the system required cryogenic cooling. That and the array of control and recording gear had driven the need for an aircraft with a cabin big enough to take all of that equipment and up to five scientific operators and observers.
But before getting to the trials, there are a couple of incidents that I remember from some of those training sorties. Flying the big beastie became fun after one had got used to the antiquarian ambience. The controls felt heavy at first but one soon adapted to that and the stability and handling were much as one might expect from an aircraft of its size and age. We practised stopping an engine in flight, at a safe height of course, including feathering the propeller; always a rather strange sight when one looked out of the window at the stationary prop. However, carrying out that drill had to be done slowly and methodically, as it was all too easy to cut off the fuel to one engine, feather its prop and then turn off the ignition switches to the other engine!
Handling with one engine at zero thrust in the circuit pattern was no more challenging than in the Canberra, indeed the forces needed on the rudder were just a shade less, even when going around from an aborted approach. However, there was one rather academic but nevertheless entertaining item in the repertoire and that was a glide approach to land; a very unlikely event for real – with both engines ‘failed’. This was flown from a 1,500ft downwind leg and, after a level turn onto base leg the throttles would be closed. The landing gear was already down and mid flap selected. Then when one was certain that the aircraft would land about one third of the way down the runway, full flap was selected and the nose lowered to keep the speed at about 110kt. The ensuing attitude was very nose low and the rate of descent concomitantly high. The glide angle was now way above 10° and from both inside and outside the old bird looked like it was doing an imitation of the Space Shuttle that was to come later!