reflected the heat toward the ground, making the plane more visible from below. The twin fins were also mounted on a pair of booms, which proved structurally inefficient. In the stealth fighter, the fins were moved farther aft and canted outward, in a V shape (similar to the V-tail of the Beech Bonanza light plane). This also improved control effectiveness. The fins were attached to a central spine that also carried the weight of the weapons.
The Have Blue's wing sweep was an extreme 72.5-degree angle. This resulted in a poor lift-drag ratio, which cut into payload and range performance. Highly swept, low-aspect ratio wings also lose airspeed rapidly in a sustained high-g turn. The sweep angle was reduced to 67.5 degrees, and the wings were extended as far back as possible to improve performance.
Operational requirements also resulted in a change to the design of the windshield and nose. The pilot would need a heads-up display (HUD) for flight information. The plane would also carry two infrared imaging systems — one looking down, and the other looking forward. Neither the HUD nor the forward-looking system could be fitted into the Have Blue's nose shape. This gave the new design a distinctive appearance, over the more conventional shape of the Have Blue's nose section. Although operationally required, the change did slightly increase the plane's RCS.[402]
A major concern was maintenance: extreme care had to be taken with the Have Blue to preserve its stealth. With the operational aircraft, the total number of maintenance hours per hour of flight time was to be similar to that of conventional twin-engine fighters. The portion related to the stealth design was to be limited to a small fraction of the total. To meet the requirements, servicing accesses for aircraft subsystems were located in the wheel wells and weapons bays. All the aircraft's avionics were located in a single bay. This minimized the need to remove and replace RAM coating during maintenance.[403]
Most of the changes from the Have Blue were internal — a reengineered cockpit, revised inlets and exhaust system, tactical systems, a braking parachute and arresting hook, an anti-icing system for the inlet grid, fuel tanks in the wings, retractable antennae, formation and anticollision lights, an inflight refueling receptacle, and, finally, two weapons bays.[404] Each bay would hold a single 2,000-pound bomb. Those bombs would be as remarkable as the aircraft itself.
During the Vietnam War, the United States had developed laser guided bombs (LGB), better known as 'smart bombs.' The stealth fighter would be equipped with a laser. The pilot would put the laser beam on the aim point, and the bombs would home in on the laser light reflected from the target.
The guidance system would compensate for shifting winds: all the pilot had to do was hold the beam on the target. It was now possible to hit a target within inches of the aim point.
Stealth meant a single aircraft could penetrate the heaviest air defenses. LGBs meant this single plane could then destroy any target, no matter how small or hardened against attack. No longer was it necessary for massive formations to
The aircraft which emerged from the redesign had a shape similar to that of the Have Blue, but the fuselage was wider and more squat. The Senior Trend was 65.9 feet long, with a wingspan of 43.25 feet. The high canopy trailed off to a very thin rear fuselage. Seen from the front, it resembled a pyramid; from the rear, the plane looked almost flat. By late 1979, a wooden mock-up was completed. This was used to check placement of equipment and systems. A full-scale Senior Trend pole model was also built for RCS testing. This posed a security problem — such testing was done outdoors where the model might be photographed by Soviet reconnaissance satellites.
To prevent any sightings, the testing was done at night.[405]
In December 1979, a contract was awarded to Lockheed to build five full-scale development (FSD) test aircraft and fifteen production aircraft.
This would provide a full squadron of the aircraft.[406] The first Senior Trend was given the aircraft number 780, for its scheduled first flight date of July 1980.
Because of the short time, existing systems were used. The General Electric F404-GE-F1D2 turbofan engines were from the navy F/A-18, without the afterburners of the fighter. The F/A-18 also provided the multifunction cathode-ray tubes, HUD, fuel controls, stick grip, and throttles. The sensor displays were from systems developed for the OV-10D and P-3C. The navigation system was from the B-52. Other systems came from just about every Lockheed aircraft built since the T-33; these included the SR-71, C-130, L-1011, and even the F-104.[407]
Of critical importance was the flight-control system. Like the Have Blue, the Senior Trend was aerodynamically unstable. Harold C. 'Hal' Farley Jr., the Lockheed test pilot selected to make the first flight, later described the plane's 'aerodynamic sins': 'In fact, the unaugmented airframe exhibits just about every mode of unstable behavior for an aircraft; longitudinal and directional instability, pitch up, pitch down, dihedral reversal, and various other cross axis couplings. The only thing it doesn't do is tip back on its tail when parked.'
It was obvious that a computer-controlled, fly-by-wire system was needed.
There was no manual backup system because it was impossible for a pilot to control the plane without the computer. To reduce risks, it was decided to use a proven off-the-shelf system. The F-16's fly-by-wire system was selected; actuators, flight-control computer chassis, and power supply were modified slightly. New computer programs had to be developed.
The control system was designed so the Senior Trend would handle like 'an ordinary plain vanilla aircraft.' Programming was tested on an NT-33, 'by real pilots flying in a real airplane in real turbulence.' Some flight tests assumed the directional stability of the Senior Trend was even worse than predicted.[408] It would prove to be a wise precaution.
Despite the Skunk Work's best efforts, by the summer of 1980 the project was behind schedule, and the first flight was nowhere in sight. Each day seemed to bring new problems and no solutions. Ben Rich said years later that this was the low point of his life. The meetings went from before dawn and continued long after dark. In the midst of this, Ben Rich's wife, Faye, died of a heart attack, leaving him emotionally devastated. When he returned to work, Alan Brown, the Senior Trend program director gave him a note. Written on it was Rich's next birthday 'June 18, 1981.' When Rich asked him about it, Brown said, 'That's the date we test-fly the airplane.'
He continued, 'The date is firm. In granite. Count on it.'[409]
By the fall of 1980, aircraft 780 was beginning final assembly at Burbank. By early June 1981, final checkout was completed. The wings were removed and crated. The fuselage was covered in a shroud, and a wooden framework was added to the nose to further hide its shape. Under cover of darkness, number 780 was loaded aboard a C-5 and flown to Groom Lake.
Upon arrival, 780 was taken to a hangar at the south end of the flight line and reassembly began. Even here, security remained paramount: a camouflage net was stretched across the open hangar door. Once assembly was complete, static engine test runs were made. The plane was kept inside the hangar, with the exhaust vented out the open door.[410]
When delivered, 780 was a dark gray color. Before the first flight, patterns of light blue and light brown were painted on the aircraft. As with Have Blue 1001, this three-color finish was meant to hide the faceting. (780 was the only one of the FSD aircraft to be camouflaged.) The paint finish was ragged looking and appeared to have been hurriedly done.[411]
On June 18, 1981, just as Brown had predicted during the dark days of nearly a year before, everything was ready. As dawn broke, 780 was rolled out of its hangar for the first time. Hal Farley ran up the engines, and 780 started down the runway. As with the first hops of both the U-2 and A-12, it was to be an eventful flight.
It was a difficult task to design an air-data system that was stealthy. Four probes extended from the nose, along with a conventional boom. Because the air-data probes had shown erratic readings during ground vibration testing, it was decided to ballast the aircraft to a far forward center of gravity point, turn off the angle of attack, and sideslip measurements to the flight-control system.
Immediately after 780 lifted off the runway, it became apparent to Farley that the directional stability was much worse than predicted. Farley immediately switched on the sideslip feedback to the flight-control computer. The plane's handling 'stiffened up,' and the rest of the flight was routine. Subsequent analyses indicated the Senior Trend's directional stability and directional-control power were less than predicted. The solution was to increase the area of the fins by 50 percent. The new fins were installed by the fall of 1981. This cured the instability but would cause other problems later in the test program.[412]
Two more test pilots soon joined the program — Skip Anderson (air force) and Dave Ferguson (Lockheed).
