by Mike Brooke
After I had set us up I did what I always did in the Hunter and aimed for a point a few hundred metres short of where I wanted to land. Holding the speed at 230kt was not difficult and I just held the little jet pointed at the white expanse of salty mud. The gradual flare towards a low go around was no problem and I was encouraged to go back up to 30,000ft for a second and final approach. That went well although my eardrums were beginning to suffer from all the changes in pressure.
Jay then threw in a bit of tourism and we flew down the length of Death Valley, at the minimum allowed altitude of 2,000ft. But even from that height the place was impressively awesome. It was easy to sense the desolation that gave it its name. There were old buildings and tracks, leftovers from the late nineteenth century when the men who extracted the mineral borax shipped it out using mule trains. Back at Edwards Jay let me fly a few visual patterns and I found that handling the T-38 was a bit like the Jaguar, although it could fly at speeds about 20kt lower.
That evening Dave Spencer, with whom I had flown the F-4 the previous year and who was still serving on the school, invited me round to his home for an evening meal. When I got there another couple had already arrived. He was another of the USAFTPS staff and while we were chatting his tall, blonde wife got up and went into the adjoining room. It soon became obvious that there was a fairly new baby in there. Over the meal I asked about opportunities for spouses to work and the new mother said that she worked on the base.
‘Oh, what do you do?’ I asked.
‘Well, I’m still on maternity leave but otherwise I head-up T-38 operations here,’ she replied. I assumed that this would be in some sort of civil service administrative role.
‘I flew a T-38 today; I really liked it – it’s a great jet for the job here,’ I said. ‘Yes, I like flying it too,’ came the response.
Well, this was well before the first women entered the RAF as pilots so I was a bit surprised; I tried not to show it. But I was intrigued by the small person in the next room.
‘How long before you had the baby did you have to stop?’ I asked.
‘Well, once I was sure that I was pregnant they restricted me to a maximum of 3G and then I stopped at six months.’
‘When will you be able to start again?’
‘In a couple of months now,’ she said coolly.
We then talked about all sorts of other flying related topics – as pilots do when they get together!
The following day started with a hugely pleasant surprise.
‘Brookie,’ John Thorpe announced, ‘you and Jock are going to fly the F-15.’
‘Wow!’ I replied. ‘I suppose that you don’t mean together?’
‘No, you silly boy. You go today and Jock has a trip tomorrow.’
I was told to get transport to the F-15 Joint Test Force (JTF) on what was known as ‘Constructors’ Alley’. The JTF was the final stage of test and evaluation in which both the manufacturer of a new aircraft type and the service user carried out all the tests that would culminate in the aircraft being acceptable for service and operationally effective.
When I arrived I was introduced to Major Steve Cherry who was going to sit in the back seat of one of the prototype F-15 Strike Eagles while I flew it. Heroic medals came to mind! The Strike Eagle was a modification to the basic F-15 interceptor fighter to enable it to fly attack missions carrying a wide variety of ordinance. There were also modifications to the landing gear to allow the Eagle to operate at higher weights and the carriage of extra fuel tanks fitted to the outside of the fuselage. These were known as conformal (zero-drag) tanks and McDonnell Douglas, the F-15’s manufacturer, claimed this as a world’s first. I didn’t have the heart to tell them that the conformal (zero-drag) bomb-door fuel tank on the Buccaneer had been flying for about fifteen years by then! The other major modifications were to give the F-15 a new high-definition radar for accurate ground mapping and target acquisition and multi-mode electronic cockpit displays.
However, Steve explained, the airframe that we were going to fly (tail no. 77-0166) was an F-15B two-seat trainer that had yet to receive all of those modifications. He said that we would fly with an all-up-weight at take-off of 48,000lb, whereas the Strike Eagle would routinely operate at weights up to 68,000lb. To prepare me for this momentous event Steve first gave me a run-down on all the essential items I would need to know, especially on how to start the engines, as he could not do that from the back seat. Illustrations of the HUD, instrument panels, actions in the event of engine failure or fire and the ejection drills were all covered.
I was then given a checklist and Steve took me to the big grey bird sitting on the ramp, alongside two other single-seat Eagles. He showed me how I was going to strap in and the location of all the really important knobs and levers.
‘OK, you stay there and work your way through the checklist,’ he said. ‘I’ll order us a burger for lunch, so come back to the crew room at midday.’
So, being a good little Brit pilot I did what I was told. By noon I felt sufficiently confident that I could fly this big beast well enough for Steve not to have to grab his stick and throttles too often and I dismounted via the ladder. The cockpit was about 8ft from the ground, much like that of the Lightning. As I reached terra firma I saw that the person that had been sitting in the single-seat F-15C alongside my steed had also climbed down. I looked at him and recognised immediately the crinkly features of no less a personage than Chuck Yeager! He looked across at me and nodded so I went up to him and introduced myself. He was intrigued as to what a ‘limey’ was doing here. I told him. As if in reply to my unasked question as to what he was doing he explained that he was going to ferry the F-15C back to the manufacturer’s plant near St Louis. I asked him how much time he had on the F-15.
‘Enough,’ was the laconic reply.
Chuck Yeager was a Brigadier General in the USAF Reserves and so he was allowed to fly occasionally for Edwards. It was uncanny to be walking alongside and chatting to this legendary man. He had gunsights for eyeballs!
After consuming my burger and wishing General Yeager fair winds and a safe arrival at St Louis, Steve and I kitted up for our flight. Before the flight I had been taken aside by OC ETPS, Robin Hargreaves, and asked to concentrate on assessing the Eagle as a ground attack machine; I was also asked to write a post-flight report, but not to disclose this to anyone else yet. Much later I learnt that the RAF was considering the acquisition of the Strike Eagle to replace the Tornado in the 1990s. This intention was highly confidential; hence I was not told at the time. Accordingly I asked Steve Cherry for some low-level flying, air-to-ground attack profiles as well as any self-defence manoeuvres using the radar.
We walked out to the jet and I climbed aboard and strapped in while Steve checked the exterior of our steed was all that it should be. The first event was to start the small jet engine in the back of the F-15, which would then be used to start the engines; it was known as the Jet-Fuelled Starter (JFS). This was a very similar system to that in the Hawk. However, a rather strange American practice was not to have batteries in their fighters, so to start the JFS I had to give it the impetus via a pull-cord on the inside of the right foot well. It was just like starting my motor mower back at home! I pulled the cord and, unlike my motor mower, it started first time. I could hear the whine of the little jet engine behind us and an indicator light came on to prove that it was up and running and ready to do its job. I then had to select the start switch to the left to start the port engine. Beforehand Steve had told me that the checklist for this bit was misleading. It told me to open the high-pressure fuel cock, by moving the throttle forward through a detent, when the engine had reached 12 per cent rpm. However, the rpm gauge was electrically operated and the aircraft’s generators would not come on-line until 18 per cent. So I had to count five seconds and then open the port throttle. I did so and there was a satisfying, deep rumble as the engine started winding up. Sure enough at 18 per cent the whole cockpit came to life with lights and cap
tions suddenly illuminating.
After we had got both engines going and all the captions on the rather large warning panel at the lower right of the instrument panel had gone out I carried out the post-start checks and before too long we were on our way to the end of Edwards’ westerly runway. The field of view from the cockpit was terrific; the sills were down at elbow level and I could easily see over the down-swept nose. The nose wheel steering operated via the rudder pedals but, even at idling power, the engines produced enough thrust to accelerate the jet so I had to keep braking using the large foot brakes. When we reached the holding area the procedure I had by now got used to of a man looking round the exterior of our mount started. It was then that I noticed another USAF idiosyncrasy: there was no parking brake. I had to push hard on the pedals to stop us creeping forward, especially as ‘Joe’ was out of sight below us. He seemed to take forever and, by the time that he reappeared and gave us a cheery thumbs-up, my calves were on fire! We then moved onto the runway.
But I still had to hold the brakes on once again as I ran the pair of Pratt & Whitney F100 engines up to full power. When I had made sure that there were no warnings showing and that the engine indications were all satisfactory I could relax my legs and off we went. I immediately selected full afterburners and within seconds we were at 125kt, which Steve had told me was the speed that I should pull back on the stick to get us off the ground. As soon as we were up I retracted the undercarriage with the chunky lever on my left and kept the nose coming up to hold 250kt, using the HUD to monitor everything.
Before our flight Steve had said that we would do this ‘Gee-whiz’ departure – ‘just for the fun of it’. Hence we were lying on our backs holding 250kt in a near vertical climb. This was even more impressive than the Lightning! We were on our way up to 36,000ft. At 15,000ft Steve asked me to turn right, using 45° of bank, and to hold 0.9 Mach. As I turned I could easily pick out the far end of the 15,000ft runway still well ahead of us, we were still over the middle of the airfield and climbing like a homesick angel!
We were headed for the local supersonic corridor over the desert to the north-east of Edwards and as I approached 33,000ft I overbanked to help us level off at 36,000ft. Steve told me to keep the ’burners on and accelerate to 1.5 Mach. That took virtually no time at all and I then throttled back to hold that speed. It was less than two minutes since we had lined up on the runway and we had not made the most energy-efficient climb profile. It just showed that a 20-ton aeroplane propelled by 24 tonnes of thrust is a real fighter pilot’s flying machine!
I was then encouraged to handle the Eagle at this supersonic speed, pulling up to 6G, rolling through 360° in both directions and simulating a gun or missile tracking task; the aircraft handled immaculately. Now it was time to slow down and descend for some manoeuvring at around 10,000ft, which was equally impressive. Using up to 30° AOA and 7G the fighting agility was well demonstrated. Then we did a deceleration in level flight to around 45° AOA: the speed was now less than 100kt and the aircraft felt to be right on the edge of controllability. Steve had said that I should use the ailerons to keep the wings level – ‘but gently!’ he added. He also told me to watch the rudders in the rear-view mirrors as I did so. I could see that, as we hung there, when I moved the stick left or right the rudders moved appropriately and, watching over my shoulder, there was no movement out on the wing. McDonnell Douglas had learnt from the F-4 Phantom and had mechanised the Eagle’s flight control system to use the rudders for lateral stability and control at high AOAs – so relieving the pilot of the need to remember to change over during his high agility combat manoeuvring.
We then did some loops from 250kt using full afterburner and up to 30° AOA. The G level was not high and the aircraft went round smoothly and easily within a height band of less than 2,500ft. This led into a couple of interceptions with a T-38 flown by no other personage than Sqn Ldr Nigel Wood, who had taken over from me at Farnborough and was now on an exchange tour at Edwards. Nigel was down at a couple of thousand feet and we headed towards him at 5,000ft. Steve talked me through the manipulation of the radar using controls on the throttles. Once we had a radar lock on the T-38 a small box appeared in the HUD, in the centre of which was the still invisible target. As we closed on it the box tracked down the HUD and Steve told me that when it reached the bottom of the display I was to roll inverted, pull to 30° AOA and try to level off with the box in the centre of the display. It was only out of total trust in Steve and his wonderful jet that I rolled until the desert was over our heads and pulled. There was no need to worry, she came round beautifully and in less than thirty seconds we were right behind our target at the ideal range for an infrared missile shot. After that we did a couple of manoeuvring ‘dogfights’ – Nigel didn’t stand a chance – and it was an ex-mud-mover beating an ex-fighter pilot. Like in Formula One it’s the mount that counts!
We then moved off to fly at low level for a while, heading towards Mount Whitney, into the forest-covered valleys to check out how the Eagle flew at 250ft. The ease of manoeuvrability was not an issue, however; as we gained altitude up the side of the Sierras the surface winds were obviously increasing because we started to be thrown about a lot more. After a while it was as uncomfortable as it used to be in my Canberra in the hills and valleys of southern Germany or the highlands of Scotland on a windy day. In fact after one particularly bad episode of severe turbulence I pulled up as I no longer felt totally safe at 250ft and 420kt. After that very interesting episode I told Steve that I wanted to try some simulated air-ground gunnery. I selected the correct mode in the HUD, found a prominent target out in the desert and flew a low-level pattern, pulling up to around 1,000ft before taking sight and descending. I noticed straight away that as I held the aiming mark on the target I had to push to keep it there, so the angle of descent was increasing as we closed on the target: not ideal! I tried several variations of the attack with the same result.
How time flies when you’re having fun. We had to return to base. I flew back and joined the circuit. The F-15 again showed its pedigree here too. The circuits were easy to fly; in fact I don’t think that I have found an easier aircraft to fly round the visual pattern, before or since. When the undercarriage went down the HUD recalibrated itself to give more easily read values and it was straightforward to keep speed, height and AOA correct. The final approach was equally easy to fly and it didn’t seem to matter whether the flaps were up or down, or the huge dorsal airbrake was in or out. Touchdown accuracy was also no problem. There was plenty of tailplane control to hold the nose high for aerodynamic braking effect and in the brisk headwind we could have stopped in less than 2,000ft. But we had to make the turn-off taxiway further down the runway so I let the big jet coast until we got there.
As I taxied this amazing fighter/bomber back to the ‘Eagles’ Nest’ in the bright blue desert day I reflected on what I had experienced. This machine was like a Lightning on steroids but with a lot more fuel! However, were there any concerns about its operational utility as a low-level strike/attack in a European scenario? I had to write some sort of assessment so I had to get my thoughts in order. I would later write that report and describe what I had done, what I had found and what it might mean.
Overall, of course, there was no getting away from the fact that the F-15 was an impressive and formidable aeroplane. It was breathtakingly simple for what it could do. The flight control system was not totally digital but it was heavily stabilised and had some clever ‘fixes’, such as the rudder-aileron interconnect controlled by AOA. There was also an auto-trimming system for the longitudinal control; this I found was a mixed blessing as the clue as to speed given by stick position and the need to trim was removed. This reduced slightly the overall situational awareness for the pilot and I found it actually off-putting in the air-ground gunnery attacks. It was also not operationally useful to have to push during those attacks to keep the aiming point on the target. This was due to the fact that, as standard on an air-to-air
fighter, the gun had been installed in the right wing root at an angle of 2° above the longitudinal fuselage datum. That was a normal practice for fighters where a bit of built-in lead angle was helpful. But for a ground attack aircraft the gun is usually depressed by 2 or 3°, just to avoid the unsafe situation of the attack dive steepening, as the ground got closer. The fact that the gun was built into the structure of the wing might be a fundamental problem. I would also like to have more than one gun for the attack role. I had suffered many ‘stoppages’ on one gun during my operational tour of ‘mud-moving’ and having at least one ‘spare’ was a good idea.
Another rather negative factor was the response of the F-15 to low-level turbulence; this is known as ‘gust response’. Because of its low wing loading, that is the wing area divided by the weight, and the design of the wing’s cross-section to give a rapid increase of lift with increases of AOA, the F-15 became uncomfortable and less easy to fly accurately when contour-following at low level in high winds; I thought that this was undesirable. It would get better at higher weights but not by much. Some sort of gust alleviation system might have to be built in.
Then there was the size of the jet. It was well known that in mixed fighter combat exercises the radio call of ‘Where are you in relation to the F-15?’ was often used because it was so big and easily picked out in a busy sky. Some pilots even called it the ‘Flying Strafe Panel’! Size does matter, whether for visual or radar acquisition. It was, I wrote, sobering to note that this fighter is only a few inches shorter than a Lancaster bomber, has similar empty and maximum operating weights and just less than half the wing area. Not a showstopper but something else to be taken into account. Of course, it wasn’t down to me to make any sort of decision – that was for the masters.