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Aviation History
1989
1989 - 0079.PDF
The F-l 11 from the cockpit The RAAF aircrew call the F-l 11 "The Pig", not because of any adverse handling characteristics, but because it has a long snout which spends a lot of its time snuffling along close to the ground. The first thing I note on climbing into the F-l 11 is the view over the long nose, which sticks out way ahead of a very deep instrument coaming. The bottom edge of the curved windshield is about two yards ahead of me, so the view down and ahead is cut off. As F-l 11 instructor Fit Lt "Boomer" Taylor explains, "That's no problem with Pave Tack, the nav can look ahead on that, but with this [an RF-111B] we have a closed-circuit TV camera just aft of the nosegear so we can line up on the target. At high level the nose blocks the view of the ground ahead for about 20 n.m." As we taxi out, I put our target co ordinates into the archaic INS, which is a real pain to use. Boomer reads out the lats and longs. "OK, that's North 48 . . .," I say. "No, mate, South. We don't have that much fuel," says Boomer. Red-faced, I crank in the numbers. You twist a spring-loaded knob, and the co-ordinate numerals click round on their drums. The harder you twist, the faster they go. Twist one way to increase, the other way to decrease. The system can store three destinations, to use as. waypoints. It is time consuming and laborious enough to do while taxiing; later I'll find what a pain it can be. We pull up into a max angle climb from the runway at 9 Alpha and 190kt. Boomer eases the wings back to 26° as we swing east to overfly Brisbane at 15,000ft, checking out the automatic terrain following (ATF) systems. We obtain clearance into the super sonic low-level corridor as we complete the checks with 200ft on the Set Clearance Plane and select "Hard" on the "Soft/Medium/ Hard" ride selector. The last check is to see that the failsafe auto-pull-up works. Any faults in the ATF chain and the aircraft will pull up at 3g.. Terrain following "OK, all ready? Let's go down," says Boomer, engaging the ATF and pulling the wing back. The nose pitches down, hesitates, and pitches down again, Boomer is sitting with his hands on his knees as we descend rapidly. At 1,000ft the nose starts pitching up, giving us 2g until we are straight and level at 200ft. "Now watch this." The noise levers go forward and the wing sweeps even further back as the afterburners kick in. The sea rushes past, and as we go supersonic there is just the slightest tremor. Boomer hand-flies us down to 100ft and Mach 1-2. The sensation of speed is fantastic. I look in the mirror: behind us a ball of spray erupts from the sea where our shock The "Pig" in its element—low and fast wave hits. But what really sticks in my mind are the fuel flow gauges. In full afterburner the left engine drinks 52,5001b/hr and the right 62,5001b/hr, with the turbine inlet temperatures hovering around 1,100°C. Taking a glove off, I note that the canopy is getting hot to the touch. We maintain this dash for a minute or so before pulling up and slowing down to a pedestrian 200ft/540kt. Auto-toss We carry out a laydown attack on Snapper Point range, then swing around south for a 270° turn to head north for a Pave Tack auto- toss profile demonstration. After the 3g pull- up and release Boomer racks it round in a 4g manoeuvre designed to allow the Pave Tack to continue lazing the target as we escape at low level back to the south. "Now let's update the nav kit," he says, reeling off a string of numbers for me to tweak into the "Present Position" number cruncher. This is not so easy, because Boomer is pulling us hard round to cross over the centre target on the range, whose co-ordinates I am desperately trying to feed while fighting the g, avoiding the stick, and trying to keep my head up. It really is a pain compared with the modern systems I have used before. I get the numbers in and press the "Fix" button as we cross the target. The kit declines to accept it, so we turn hard and overfly again. This time it goes in, and the INS is updated. We head inland towards the Great Dividing Range for some low flying. The terrain-following radar has a narrow beam width, so in Auto TF the aircraft often passes extremely close to high terrain on either side. Auto TF is usually a night/bad weather option. In daylight the pilots prefer to fly the TF, following pitch demand bars on the AHI and keeping an eye out ahead. Using the AHI will give the lowest terrain clearance (set in multiples of 200ft) for the ride quality selected: soft, medium, or hard. We select 200ft, hard ride, and bat along at Mach 0 • 9. There are no problems with that, so we decide to do Auto TF. The system takes over, and Boomer sits back with his hands on his knees. "Pretty good, eh?" I am watching a hill dead ahead. "What? Oh .. . er .. . yes." The Auto TF pulls us up and, as we start to clear the ridge, pushes us down again. In hard ride it is a -g push which lasts for several seconds and is absolutely delightful. Approaching the next ridge Boomer removes a glove. As we unload to Og again he tosses it in the air, where it floats gently back wards until the g comes back on to position us in a valley. "In hard ride the system leaves it later for the pull-up, to keep your exposure time down as you cross the ridge. At night I would monitor the E-Scope TF presentation and the nav looks at his attack radar display for terrain avoidance in azimuth. Look how close we pass to this feature ahead and you will see what I mean about the narrow TF beamwidth." A small mountain slides past very close. "Good thing about night flying; you don't see them," laughs Boomer, "but we would like a moving map display so we can better plan our terrain avoidance, I doubt if we will get it, though." Reducing the workload After ten minutes, I am totally confident in the Auto TF and feel at ease. We are chatting unconcernedly about what we are going to do next, and we are also free to keep an excel lent lookout all round. In short, the Auto TF leaves the crew free to think tactics and keep ahead of the game. With a digital nav attack system the workload in the right-hand seat will be much lower, and the overall system accuracy will be much improved. Old the F-l 11 may be, but the digital update will rejuvenate it. B FLIGHT INTERNATIONAL, 14 January 1989 21
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