Fighter Wing: A Guided Tour of an Air Force Combat Wing tcml-3

by Tom Clancy

  The gestation period of a modern aircraft may take as long as fifteen years from first specification to squadron service. And there may be several generations of production models built, with up to twenty-five years of total production. If this period seems long, consider the McDonnell Douglas F-15 Eagle. It was first designed in the late 1960s, went into production in the mid-1970s, and has remained in continuous production ever since. Given the current backlog of orders to Saudi Arabia and Israel, and other possible production orders, the third-generation Eagle variants will be in production and in service for over twenty-five years, until approximately 2015 to 2020.

  An F-15C of the 366th Wing/390th Fighter Squadron on the flight line of Nellis AFB during Green Flag 94-3. It carries the standard load of three 610 gallon/2,301.9 liter fuel tanks and eight air-to-air missiles.

  Craig E. Kaston

  So read on, and get to know some of the classic aircraft being flown by the USAF, now and in the future.

  MCDONNELL DOUGLAS F-15 EAGLE

  In July 1967 at Domodedovo Airport, outside Moscow, the Soviet Air Force proudly unveiled a new aircraft to the world press, the Ye-266/MiG-25. Nomenclature rules used by Western intelligence agencies specified that all "threat" fighter types got names starting with the letter F; so the MiG-25 was called "Foxbat." Like its namesake, the world's largest flying mammal, this new plane was a beast with remarkable sensors, sharp teeth, and impressive performance. It quickly established several new world records for altitude, speed, rate-of-climb, and time-to-altitude, all important measures of a fighter's capability in combat. The best contemporary American fighter of the time, the McDonnell F-4 Phantom, was clearly outclassed; and the U.S. Air Force launched a competition to design a plane that could surpass the Russian achievement. This program became even more vital when you consider that the same airshow had seen the rollout of the MiG-23/27 Flogger-series aircraft, and a number of other impressive Soviet fighters as well. Quickly, the USAF produced a specification for what they called the Fighter Experimental (FX). Several manufacturers competed for the FX contract, which eventually went to McDonnell Douglas in St. Louis. The contract was awarded in December 1969, and the first F-15, dubbed the "Eagle," was rolled out on June 26th, 1972. By the end of 1975, operations of the first F-15 training squadron at Luke AFB, the famous 555th "Triple Nickel," were in full swing; and the 1st Tactical Fighter Wing (TFW) at Langley AFB, Virginia, was fully equipped with its cadre of the new birds. There were 361 F-15A fighters and 58 combat-capable F-15B trainers produced before the improved — C and — D models went into production in 1979. In early 1995 the Air Force operated about twenty squadrons of F-15s, including five Reserve and National Guard squadrons.

  The designers at McDonnell Aircraft produced a 40,000 lb./18,181 kg., "no-compromise" air superiority fighter that, superficially, resembled the Foxbat, with huge, boxy air intakes, large wing area, and tall twin tail fins. The exterior is covered with access panels, most at shoulder level for easy access without the need for work stands. The structure made extensive use of titanium (stronger than steel) for the wing spars and engine bay, and limited use of advanced boron fiber (non-metallic) composite materials in the tail surfaces. Stainless steel is found mainly in the landing gear struts, and the skin is primarily made of aircraft-grade aluminum. By comparison, the Foxbat used heavy steel alloys throughout the airframe. This imposed a huge weight penalty on the Soviet machine. In case you wonder about the strength of the American bird, consider that McDonnell Douglas's F-15 test airframe has completed over eighteen thousand hours of simulated flight, which represents a potential service life of fifty-three years, based on a flight schedule of three hundred hours per year.

  According to the original FX design guidelines, the aircraft was to be a pure air-superiority fighter—"not a pound for air-to-ground." Earlier designs like the F-4 Phantom and F-105 Thunderchief had traded off air-to-air performance for a multi-role "fighter-bomber" capability, and this often put them at a fatal disadvantage against the more agile Soviet MiGs, such as those that they encountered over North Vietnam. (Later, as it happened, the Strike Eagle derivative of the F-15 became one of the great air-to-ground combat aircraft of all time.)

  The F-15 used the very advanced Pratt and Whitney F100-PW-100 turbofan, which pushed then-existing technology to the limits. The 17,600lb./ 8,000 kg. thrust J-79 engine, for example, two of which powered the F-4 Phantom, had a turbine inlet temperature of 2,035degF/1,113degC, while the F-100-PW-100 turbine inlet can sustain a hellish 2,460degF/1,349degC. In full afterburner, the basic F100 produces 25,000 lb./11,340 kg. of thrust — nearly eight times its own weight! A skilled ground crew can remove and replace an engine in thirty minutes; just try that on your Oldsmobile! In service, F100 engines have worn out much faster than expected, principally because the Eagle's advanced airframe allowed pilots to fly on the "edge of the envelope" at throttle settings and angles of attack that stress the engines severely. But the edge of the envelope is where pilots win air battles, so the price has been paid to maintain the awesome capability that the F100 delivers.

  One of the realities of modern jet fighters is that they burn gas faster than teenagers drink diet soda — a lot faster. While the F100 turbofan is more efficient than the older turbojet fighter engines, they still burn a huge load of fuel, especially in afterburner. To feed the two big turbofans, the Eagle carries a huge load of fuel internally, in the fuselage and wings. In addition, all F-15s can carry up to three external 610 gallon/2,309 liter drop tanks, one on the centerline and one under each wing. To extend the Eagle's unrefueled range even further, McDonnell Douglas developed the Fuel and Sensors, Tactical (FAST) Pack, a pair of bulging "conformal" fuel tanks (CFTs) that fit tightly against the sides of the fuselage below the wings. These are designed to minimize drag and actually generate some lift, so the Eagle's performance is only slightly affected. Holding 750 gallons/2,839 liters of fuel, each CFT can be installed or removed in fifteen minutes. In addition, there are fittings on each CFT for mounting bomb racks or missile rails. CFTs are not carried on the current fighter version of the Eagle, the F-15C, because the normal internal fuel load, as well as that in the drop tanks, is usually adequate for the missions the Eagle drivers fly.

  The business end of the Eagle is the cockpit, which is topped with a large bubble canopy. It provides exceptional panoramic visibility, which is critical to survival in a dogfight. F-15 pilots talk about a feeling of riding "on" the aircraft rather than "in" it. By slightly extending the canopy, the design left sufficient room behind the pilot for a second seat, making it relatively simple to build the F-15/D operational trainer, and ultimately the F-15E Strike Eagle.

  The pilot sits in a McDonnell Douglas ACES II ejection seat, which is one of the best in the world. When you sit in one, you are held by a lap belt and shoulder-harness system, and the cushions contain the parachute and rescue packs that deploy when the seat separates. All you need to do to escape from a stricken aircraft is to pull one of the two sets of ejection handles (one on either side of the seat) while sitting firmly in the seat, and you are on your way. Pyrotechnic charges blow off the canopy, and then a rocket motor fires and blasts you free. At that point, everything, including the parachute deployment, is handled automatically. Even the release of the parachute in the event of a water landing is handled by sensors that detect the presence of water and cut the riser lines loose to keep the survivor from fouling the chute and drowning.

  While the instrument panel directly in front of the pilot is crammed with a mix of dial gauges, most of what he actually uses centers around just three things, the Heads-Up Display (HUD), the control stick, and the throttles. Earlier we saw how the HUD presents the most vital flight and sensor data to the pilot, without the pilot having to move his gaze down into the cockpit. This is critical, because the last thing you want to do in a dogfight is take your eyes off the target. Most of the controls that an F-15 pilot needs for fighting in the Eagle are located on the control stick; engine throttles
are on the left side of the cockpit. Both are studded with small switches and buttons, each shaped and textured differently, so that after a short time, a pilot can rapidly identify a particular switch just by feel. This system — known as Hands on Throttle and Stick (HOTAS) — was developed by a brilliant McDonnell Douglas engineer named Eugene Adam, who is a legend in the business of cockpit design, having also been behind the "glass" (using computer MFDs instead of dials and gauges) cockpits in the F-15E Strike Eagle, the F/ A-18 Hornet, and many other combat aircraft in service today. The HOTAS switches control almost everything a pilot needs in a fight — the radar mode, radio-transmit switch, decoy launchers, and of course the weapons release, which can be controlled by the movement of a finger and a flip of a switch.

  A drawing of the McDonnell Douglas ACES II ejection seat.

  Jack Ryan Enterprises, Ltd., by Laura Alpher

  While I've never flown in the front seat of an actual Eagle, I spent some time on the domed full-motion simulators operated by McDonnell Douglas at their St. Louis facility. When you sit down in the seat of an Eagle, the first thing you notice is that your hands just naturally move to the HOTAS controls and your eyes to the HUD. It takes a while to sort out all the switches and buttons, though you rapidly identify the really important ones. When they start it up and you're actually "flying," the first thing you notice is that your aircraft seems to wobble all over the sky, because the controls are so sensitive. You quickly learn that the trick to maintaining a smooth flight path is to loosen your grip on the control stick and let your right hand just "kiss" it with a light touch. When you start maneuvering the Eagle, the control system is just so quick and responsive to even the smallest control inputs that you feel you're "behind" the airplane. Even the twin F100 power plants are quick to accelerate and idle, thanks to the digital engine control system.

  I mentioned earlier that the Hughes-built radar of the Eagle has been a standard for air intercept (AI) radars since it came into service in 1975. Originally designated the APG-63, it has been updated to the APG-70 standard in the F-15E and the last block of F-15C Eagles. The reason for having a radar so powerful and agile (i.e., able to discriminate and hold lock even on small targets during the high-G maneuvers of a dogfight) on the Eagle was that the designers wanted to be able to scan and attack targets in a vast volume of airspace in front of the new fighter. This requires a lot of power. The brute power of a radar is determined mainly by two factors, the amount of electrical current the aircraft can supply and the space available for the antenna. The sophistication of a modern radar is determined largely by the state-of-the-art in digital signal processing, an arcane branch of computer science. The original APG-63 radar had three main operating modes: low pulse-rate (frequency) for ground mapping, medium pulse rate for close-range maneuvering targets, and high pulse rate for long-range detection at ranges of 100 nm./183 km. or more. Since the most important radar controls are located on the throttle column and control stick, they are easy to use in combat. The most important of these are the switches for selecting where the radar is pointed in elevation and the various radar modes. This system has been continually upgraded to keep pace with advances in technology, and is now designated the APG-70, with a programmable signal processor (PSP). The PSP was added to the APG-63 in later F-15A/B model aircraft; and later — C/D/E models got the APG-70 with the PSP already built in. The upgrade included a variety of new operating modes, such as Synthetic Aperture Radar (SAR) precision ground mapping in the F-15E model.

  Another important part of the Eagle's avionics is the communications suite. In addition to the new Have Quick II radios (jam and intercept resistant), there is one of the new Joint Tactical Information Data System (JTIDS) terminals, which allows the "linking" of any aircraft so equipped to an aerial local area network. This secure (i.e., unjammable and untappable) data link allows the sharing of information from a plane's sensors and other systems with other aircraft, ships, and ground units. JTIDS terminals are currently on the E-3 Sentry AWACS, as well as new E-8 Joint-STARS ground surveillance aircraft. Even U.S. Army Patriot SAM batteries, U.S. Navy Aegis cruisers and destroyers, and NATO units have the capability to tap into the JTIDS data link system. Now, while data links are nothing new, what makes JTIDS special is that it transmits a full situational report, including radar contacts, sending aircraft position, altitude, and heading, and even fuel and armament status (counting gun, bomb, and missile rounds onboard) to anyone with a terminal equipped to receive it. The major problem with the early JTIDS terminals was that they were extremely expensive; but later versions have been re-engineered to reduce their size, cost, and complexity. Luckily, the rapid march of technology has made this both possible and reasonable, and the new terminals should be in service within a year or two. Currently, only the F-15Cs assigned to the 391st Fighter Squadron of the 366th Wing at Mountain Home AFB, Idaho, are equipped with JTIDS.

  It is always vitally important that the pilot know where he or she is; thus the inclusion of a highly accurate inertial navigation system (INS) in the Eagle's avionics suite. The Litton ASN-109 INS is a "black box" that uses laser beams moving in opposite directions in rings of fiber-optic cable. Any motion of the aircraft causes tiny shifts in the wavelength of the light, which is sensed and analyzed to determine position, velocity, and acceleration. Before takeoff, the system is "aligned" and fed the geographic coordinates of the starting point (usually the aircraft parking ramp, where a sign is posted with the surveyed coordinates) and a series of "waypoints." Since INS positional fixes tend to "drift" over the course of a mission several hours long, there are provisions to update the navigational fix with inputs from ground-based aids such as the TACAN system (a series of ground-based electronic navigation stations), as well as visual and radar map fixes. A future avionics upgrade for the — C will add a super-accurate Honeywell system combining a GPS receiver with a ring laser gyro in a single box.

  Another system directed from the pilot's HOTAS controls is the defensive countermeasures system. To survive today in a high-threat environment, you need a radar jammer. In the Eagle, this system is the internally mounted Northrop ALQ-135(V), which operates automatically, requiring only that the pilot turn it on. To alert the pilot to electronic (i.e., radar guided) threats, there is a Loral ALR-56C Radar Warning Receiver (RWR), with the display mounted just below and to the right of the HUD. This display shows both the type of threat and the bearing to the enemy radar. It also can tell the pilot whether the enemy radar is just scanning, or if it has actually fired a SAM. As might be imagined, this information is vital for a pilot to survive in the modern aerial battlefield. Antennas for the ECM and RWR systems are mounted in pods on top of the twin tail fins. Should the ECM system fail and there's an incoming missile on your tail, the pilot also has a Tracor ALE-45/47 chaff and flare decoy dispenser, with the release button mounted on the left side of the throttle column.

  The only reason for the existence of a combat aircraft is to deliver (or at least threaten to deliver) ordnance (the technical term for weapons) onto an enemy target. As we stated earlier, the original design of the Eagle was for a no-compromise air-to-air (the USAF term for this is "air superiority") fighter. Thus, the F-15C weapons suite was optimized for taking on and rapidly defeating a large number of air-to-air targets. For the designers of the Eagle, their starting point was the original weapons loadout of the aircraft that it replaced, the eight air-to-air missiles of the F-4 Phantom. In addition, they decided to add a gun to the package, since the lack of such a weapon had cost American pilots so many MiG kills over North Vietnam. Unlike guided missiles, guns have no minimum range, and can also be used against ground targets, should that be required. While originally it was planned to fit the F-15 with the new Philco Ford (now Loral Aeronutronic) 25mm GAU-7, it was eventually decided that the F-15 would be equipped with the older, more dependable General Electric M-61 Vulcan 20mm six-barreled rotary cannon. Used on USAF aircraft since the mid-1950s, it is something of a classic on its own, and
is on every air superiority fighter currently in the U.S. inventory. The cannon muzzle is located in the starboard wing root, well behind the engine intake, so there is no risk of ingesting gun gas, causing an engine flameout. A drum magazine behind the cockpit holds 940 rounds, but you better fire short bursts, since this is just enough for 9.4 seconds of firing. (The M61 fires over six thousand rounds per minute!) Today, the big news about the Vulcan is that there is a new kind of ammunition for it to fire — the PGU- 28, which has armor piercing, explosive fragmentation, and incendiary effects, all in a single round. This new bullet has greatly improved the capabilities of the M-61, which is still one of the finest airborne cannons in the world. In the F-15C, the gun is angled up about 2deg, so that it "lofts" the rounds towards the target, allowing a better view before you lose sight of the target under the nose of the aircraft. There also is a new gunsight — or more properly, gunsight symbology for the HUD — which greatly eases the task of aiming. When the GUN mode is selected (from a switch on the throttle), what looks like a funnel appears on the HUD. Once you have the enemy aircraft centered between the two lines of the funnel, a squeeze of the trigger on the front of the control stick sends a stream of cannon shells toward the target. According to F-15 pilots, the new sight symbology has radically improved gunnery accuracy and makes the gun a much more dangerous weapon.

  Good as the gun is, the most powerful weapons on the Eagle are its eight air-to-air missiles (AAMs). Originally, the F-15's primary AAM was the Raytheon AIM-7 Sparrow, four of which could be carried on racks tucked neatly on the underside of the fuselage. These have since been replaced by the Hughes AIM-120 Advanced Medium Range Air-to-Air Missile (AMRAAM), which is known as the "Slammer" by pilots. Underwing pylons also can carry up to four AIM-9 Sidewinder AAMs or AMRAAMs.