by Mike Brooke
The Hawker Hunter was a product of the immediate post-Second World War era. In 1946, recognising that the future lay with jet engines and swept wings, the Air Ministry had issued Requirement Number E38/46 for just such a fighter. One of the industry responses was from the Hawker Aircraft Company of Kingston upon Thames. Their chief designer, the brilliant Sydney Camm, who had designed the wartime Hurricane, started work on a series of prototype fighters powered by a single jet engine. In March 1948 the Air Ministry issued a new Requirement – F3/48, which called for a high-speed, high-altitude, gun-armed fighter with a rapid rate of climb. Camm took on the challenge and came up with a swept-wing aircraft powered by a Rolls-Royce Avon engine that the company identified as P1067. The first version had an air intake in the nose, much like the North American Sabre, and T-tail. But during manufacture of the first prototype the intake was moved to the wing roots and the tailplane lowered to a position about halfway up the fin. It had a wingspan of just over 33ft and was about 45ft long.
So, looking much more like the Hunter that it would become in RAF service, the P1067 took to the air for the first time on 20 July 1951 in the hands of Hawker’s Chief Test Pilot (CTP), Neville Duke. That flight was from the very place that I had flown my first flight in a Hunter, only five months earlier: Boscombe Down. There was just a twenty-four-year time gap between the two events!
Eventually nearly 2,000 Hunters of many variants would be built and they would serve with no less than twenty-two air forces around the world. The RAF would use Hunters in the operational fighter/fighter-bomber and fighter-reconnaissance roles from 1954 until 1971. But the Hunter would continue in RAF service as a trainer until the eventual demise of the Blackburn Buccaneer in the early 1990s. And it was the two-seat T7 trainer version, which first flew in 1955, that I would spin first.
As I walked out with Duncan Cooke towards the always eye-pleasing and elegant-looking Hunter I reflected on the several briefings that I had received about what we were going to do in the next hour or so. It had been made abundantly clear to us all that no other flying establishment in the world carried out intentional spinning in a swept-wing aircraft. The reason for this was that the shape and thus the distribution of mass in such a design meant that the dynamic forces acting on the aircraft in the spin were different to the rather ‘squarer’ straight-winged trainers, like the Jet Provost. This could lead, and had done so in operational and training service, to pilots being unable to recover from spins.However, once the relationship between the aerodynamic and inertial forces had been fully understood and special instrumentation fitted then safe recoveries were almost guaranteed. But just to be on the safe side every spin would be monitored from the ground by another pilot.
To do that a radio system, called telemetry, in the aircraft’s nose would transmit data on a range of parameters that could then be displayed on a panel to show the ‘ground pilot’, sitting in a building on the margins of the airfield, exactly what was happening 8 miles above and usually many more miles away. Before each spin was entered the ‘test’ pilot had to tell the ground pilot the details of the type of spin, entry and recovery that was intended. The ground pilot would then monitor everything carefully and call the airborne pilot if anything looked amiss. The ground pilot could, and should, also aid the airborne pilot in calling out recovery actions if they did not appear to be working.
The complementary instrumentation in the aircraft was on a small panel, right in front of the pilot’s eyes (where the gunsight would usually be); for obvious reasons this was called the Spin Panel. It had instruments to show the position of the ailerons and rudder, a turn indicator (to show the direction of yaw), two small lights to indicate the direction of roll, an angle of attack (AOA) indicator and a special altimeter with a single needle and a scale marked in tens of thousands of feet from 0 to 4. There was also a big red light that would illuminate at 10,000ft. That was there to show that the aircraft had reached the height at which, if the spin had not stopped, the pilots should eject. It might seem high but the rate of descent in the fully developed spin in the Hunter was getting on for 20,000ft per minute; so 10,000ft was only 30 seconds from impact!
Despite all the added safety measures the exercise was still classified as ‘high-risk’ and the frisson of excitement was mounting as I strapped into the left-hand seat, next to my South African skipper. But once I was winging my way through the start-up checks and getting the machine to come to life the butterflies subsided again. While taxiing out to the runway we had to check the special radio frequency that we would use to talk simultaneously to our ground pilot and the nice folks at London Military Radar, while we were up and away on our exercise. All was well and with the checks of our telemetered data and the aircraft completed we rolled onto Boscombe’s long runway and I wound up the engine for take-off.
About a quarter of an hour later we were up at 40,000ft ready to do our first spin. I went through the radio procedures, looked out around and, as best as I could, below and put the aircraft in level flight, closed the throttle and waited for the speed to drop. At about 140kt I did just what I’d done in the JP: pulled the stick fully back and pushed the rudder bar as far as it would go. The stick in the Hunter is actually cranked slightly to the right. This was done to give the pilot a better view of the lower instrument panel, but it also made it easy for the stick to be pulled to the right as well as back. This is where that funny little gauge marked ‘Aileron’ on the Spin Panel came into its own. It was important to make sure that no aileron was applied during the spin. The reason for this would become abundantly clear to me during the next half hour or so.
The result of this coarse and rather rude handling of the controls was a big surprise. No rapid roll or pitch up – in fact nothing rapid at all. There was lots of buffet, a slow roll until the jet was inverted and then it all stopped. The nose was well below the horizon and after around eight seconds we still had not done a whole turn. As in the JP exercise the first recovery was going to be by putting all the controls to their neutral positions. As soon as I did so the rotation stopped and we were wallowing earthwards at an ever-increasing airspeed. I pulled out of the dive and recovered to level flight at about 250kt. At least I didn’t have to scribble things down on a notepad; the on-board instrumentation was recording it all and I would be provided with the output on the following day.
We had lost about 5,000ft so I put the willing old lady back into a climb to regain 40,000ft. The next two were fully developed three-turn spins. During them the aircraft showed me a stubborn reluctance to want to do this rather ungainly and unseemly exercise. There was nothing smooth, consistent or really predictable about each turn. There were times when the spin rate would suddenly increase and then decrease again, and the aircraft’s nose was going up and down with associated flicks of the AOA needle in front of my eyes. It was like a fairground roller coaster ride. But the standard recovery action, modelled on the old Parkes’ Technique, worked every time; the aircraft stopped spinning after not much more than another turn. These fully developed spins brought us down to around 25,000ft each time, so the climb back up to 40,000ft took much longer.
But we had to explore more things. One of these being the effect of having aileron applied during the spin and the recovery. So once the aeroplane was spinning properly then, under Duncan’s direction, I applied full aileron smoothly in one direction. When that was in the same direction as the spin then the whole thing became much more oscillatory; the roller coaster changed to a bucking bronco! When the aileron was applied in the opposite direction to the spin then it speeded up but became much smoother and the nose was visibly closer to the rotating horizon. But what about recovery? Well, with aileron applied, especially out of the spin, the aircraft just kept on spinning even after the rudder had been applied and the stick was moving forward. Using the neat little aileron gauge in front of my face I could incrementally reduce the deflection of the stick from central and wait a few seconds to see what happened. The aircraft did not recov
er until the ailerons were within about 10° of neutral. No wonder so many Hunters had been lost in spins. There was no aileron gauge in normal service, although there was a large white spot painted on the instrument panel which, when the top of the stick was lined up on it, meant that the ailerons should be central. So any Hunter pilot who suddenly found himself in a spin would have to concentrate very hard to make sure that there was no aileron still applied during his attempt at a recovery.
By now we had used about half the fuel load, which guaranteed that the two 100-gallon wing tanks were now empty. This was significant because until they were empty Duncan could not show me the final and most challenging feature of today’s lesson: the inverted spin.6 Now the butterflies came back to life. I, like most pilots at my stage of life, had never experienced an inverted spin and lived! In fact, inverted flying of any sort did not occupy much of the time I had spent aviating. However, I had to steel myself for a new experience. Duncan was going to demonstrate one and then I was going to have a go myself. Then we would have to go home before the fuel ran out.
So the first step was to get the jet to do this unusual manoeuvre. Duncan took control, asked me to follow him through lightly on the controls, so that I could sense what he was doing. We levelled at 40,000ft, told the ground pilot what we were going to do, got a clearance to do so, and then accelerated to 180kt. Once there Duncan closed the throttle, applied full left aileron and held the stick just forward of neutral to make sure that the nose stayed above the horizon. After about 270°, as we were about to come upright again, he firmly applied full right rudder. There was a bit of a pause while the jet seemed to work out that the only way it could roll left and yaw right was upside down.
Then it all happened. I could feel the yaw rate increase and at the same time the strong sensation of negative G came on; that very definite ‘upside down’ feeling. The loose ends of our seat straps flew up in front of our faces and a quick glance at the accelerometer showed that we were under the influence of about –2G. Duncan pointed out on the Spin Panel that the roll and yaw were indeed opposite to each other. He then told me to look at the JPT gauge. I tried to find it, but for the life of me I could not locate it! That was the effect of the extreme disorientation on my tiny brain during the brief time that we had spent in my first inverted spin.
The reason Duncan had asked me to look at the JPT gauge was because it was showing that the temperature inside the Hunter’s exhaust pipe was heading rapidly towards the red line that showed the maximum permitted in-flight value. I would later discover that this was because the airflow entering the air intakes was being disrupted because we were dropping earthwards upside down; Sydney Camm had designed the air intakes to work best when the aircraft was the right way up. As the JPT was now at the limit Duncan carried out the recovery actions, which oddly were exactly the same as for the upright spin. The Hunter responded with alacrity, almost as if it had had enough of this bizarre mode of flight.
Once I had recovered my composure and Duncan had put the aircraft back in straight and level flight he gave me control and asked me to climb back up to 40,000ft again and repeat the exercise myself. Within ten minutes we were in our final inverted spin. I had successfully got the aircraft into the spin using the same technique as Duncan and now I had to observe what was going on. The spin was much smoother than the upright one, with nothing like the wild variations in pitch and roll and, although there was that strong upside down sensation, the Hunter’s nose did not appear, from where I sat, to be in a classic inverted position. After three or so turns, which took about four seconds each, I checked the direction of yaw, applied full opposite rudder and eased the stick forward. Once more the recovery to a straight dive was fairly rapid and all I had to do was recover from that and take us home.
I thought that I might have been feeling a little queasy by now, but I was not. I had never suffered, like some poor souls did, from airsickness and I was pleased that my stomach had not been too badly affected by the gyrations of the past hour. After coffee and a good debrief I was sent away to think about what I had seen and prepare myself for another similar sortie. Then I would be going off in a single-seat F6A Hunter to carry out a full spinning assessment of my own.
The second sortie in the T7, again with Duncan, had a positive, reinforcing effect on my knowledge, powers of observation and my equilibrium. We repeated much of what we had done on the first trip but there was something new to experience. This was related to the spin recovery with aileron applied, which I would have to do during the solo exercise. During these tests it was important to apply the aileron before starting the recovery, so the stick had to be moved smoothly and fully in the chosen direction while the aircraft was still spinning. However, if this was done during one of the periodic hesitations, when the jet was just sitting there, buffeting but not rolling or yawing, then it could cause the aircraft to flip into an inverted spin. As we students were not permitted to carry out intentional inverted spins during our solo test exercises we had to be shown how best to avoid this unwelcome outcome.So, towards the end of our second spinning sortie together Duncan talked me through the whole procedure.
First, I applied full left aileron while spinning to the right just after the second time that the Hunter’s natural reluctance to spin had caused a short hiatus in the proceedings. Sure enough the spin continued, sped up and flattened out a bit, and I recovered as I had done previously, gradually reducing the stick deflection until the spin stopped.
But that was not to be the end of the day’s rotational excitement. The next and final event was the application of aileron at the hesitation – just to prove to me what would happen.
‘It’s not guaranteed, lad,’ said Duncan. ‘But the odds are in favour of an inverted outcome.’
I duly put the Hunter into yet another spin and waited until things slowed down for a second or two. While the aircraft was wallowing in uncertainty as to what to do next I whacked on full aileron. There was a barely perceptible pause and then with breathtaking rapidity the dear old Hunter flipped into the upside down mode. The negative-G sensation seemed even stronger than before and the rate of rotation whipped us around with eye-watering speed.
‘OK, Mike, recover,’ came the words from Mr Cool on my right.
I complied and so did the jet. By the time I had got us back to normal flight I had recovered my composure; I hoped that Duncan had not noticed that I had lost it. Time for home and tea.
During the last ten days of June I flew my four spinning assessment sorties; three in the F6A and one in the T7. Much of what I had seen on my two introductory sorties was repeated, but this time I had my voice recorder, test cards and the output from the on-board data recording system. Being in the single-seat Hunter did make a difference, especially in being able to see out better and climb back to height a little quicker. Most of my test plan went as it should have. There was just one occasion when I was exploring the application of out-spin aileron that I felt that sudden onset of negative G! I recovered promptly. The ground pilot, watching the instruments from so far away, just chuckled.
Without doubt this ETPS exercise was the most demanding physically, if not intellectually. We had to record and present a lot of data, facts and give an opinion in the form of a recommendation as to whether intentional spinning should be authorised in the Hunter. I thought that it could but only if a spin panel was fitted. However, the preferred solution was ‘No’! Although most of us would never be called upon to participate in a full spin programme it did teach us how to conduct high-risk tests properly, how to learn to overcome disorienting and disturbing motions and how to record and report in a high stress environment. All skills we were going to need in our future test flying roles, wherever they took us.
Of course, spinning was not the only test exercises we did during those two glorious summer months of June and July 1975. That would have been much too easy. No, the school had to keep loading us up with ten-day deadlines for reports; it was part of the ethos. I al
so flew the Lightning again, trying to establish its rates of roll under a variety of conditions. This test exercise was a constant competition between the number of test points I could complete against the amount of fuel left in the inadequate tanks. Then there were more sorties, similar to those we had flown in the first term, in the Variable Stability Basset, supposedly solving more aerodynamic mysteries. Then I did yet more flying in Hunters, this time exploring the speed, turning and climbing capability of this ageing fighter in an exercise called Manoeuvre Boundaries. This was a way of turning lots of fuel into barely comprehensible lines of recorded data. Much time was spent, late into the evenings yet again, deciphering, reducing, calculating, assessing, reporting and recommending; all without the use of computers! For the course I had spent what was then an enormous amount of money to replace the slide rule that my dear old dad had given me with the latest Hewlett Packard pocket calculator; and your pocket would have to have been quite copious!
The term finished with a series of flights in the little dog – the Beagle Basset. This was under the auspices of an exercise called TOL, the acronym for Take-Off and Landing. This was predominately a handling exercise, although, as usual, a great deal of numerical (known in the business as quantitative) data had to be recorded and used to back up the pilot’s observations (known in the business as qualitative data). The final event of the term for me was yet more rotational flight: a trip in a helicopter, which I was allowed to fly for some of the time. This was in the Westland Scout, possibly called that because it could lift, in addition to the crew, just one boy scout. That is a bit unkind, but I was mightily impressed how quickly it came down once the engine was no longer powering the whirly bits above my head. I suddenly came to see why helicopters have windows just above your feet. It’s so you can see where you are going to land when the engine has quit! It was good to reach the end of a frantic nine weeks and look forward to three weeks holidays. No reports to write. No data to analyse. Just novels to read. A lot of sleep to catch up on. Chance to spend a lot of quality time with my wife, Mo, and the two little ones, Sonia and Peter.