Have Blue

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That's right, four ejections and he lived to talk about them all. Ken Dyson was the only pilot to fly Have Blue 2. The Skunk Works team proved stealth could work with Have Blue 2. As Dyson put it: Ken experienced seven negative Gs while trying to escape from the flailing experimental jet and his chute opened as he was ejecting. He was only up for ten minutes before he ejected at 20, feet.

It would take another ten minutes before he hit the ground. The cause of the crash was a loose engine clasp that allowed hot gasses to damage the aircraft's hydraulics. Have Blue had a variable geometry platypus tail kind of like the one on the B It was called the "Platy" by the test team. Tacit Blue was only flown by five pilots. Its notoriously ugly looks made for some great one liners, including "they forgot to take it out of the box! Tacit Blue's tail had a span of 24 feet, two feet wider than the entire wingspan of Have Blue.

The aircraft had bad hydraulic problems before its first flight, with the system finally working on the 19th ground engine test run. The closely spaced engines that shared a common air inlet could only be started at nearly the same time because after one was running the other wouldn't get enough air. They still look ripped straight from science fiction: Don't forget to sign up. It combined long-range radar that could detect high-flying attack aircraft from hundreds of miles away, electronic warfare sensors that could detect the ground-following radar of low-flying aircraft passively, and radar-guided surface-to-air missiles and anti-aircraft guns.

And a Defense Science Board study in concluded through war-gaming out an air war with the Soviet Union in a conventional invasion scenario—specifically, the Fulda Gap scenario at the center of most Cold War military strategy at the time—that the US had to develop some technology to counter those defenses. The challenge would have seemed like an ideal fit for Lockheed's Skunk Works, given that the organization had been producing "low observable" aircraft for the CIA and Air Force for years.

The previous U-2 surveillance plane wasn't technically a "stealth" aircraft, but it was coated in radar absorbent material. Despite its size, the design of the SR reduced its radar cross section to that of a Piper Cub, making it difficult for long-range radars to detect at least until it was too late for someone to shoot at it.

But this was a stealth fighter project, and Lockheed had not built a fighter jet for over a decade. While Lockheed had experience with low radar cross-section aircraft, its work was so classified that the DARPA project team didn't know about it.

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Ironically, at about the same time, Denys Overholser—a Skunk Works mathematician and radar expert—discovered equations in a nine-year old research paper from Russian scientist Pyotr Ufimtsev. Recently translated by the Air Force's Foreign Technology Division, the paper reworked some of Maxwell's Equations to predict the radar reflectivity of a geometric shape. In his memoir , then-Skunk Works chief Ben Rich called the equations the "Rosetta Stone breakthrough for stealth technology.

The equations were eventually used as the basis for a computer program called Echo 1, which would allow engineers to break down the design of an aircraft into a series of triangles to calculate their radar cross section for any particular angle of attack.

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From there, this allowed engineers to optimize the shape of an aircraft for the smallest possible radar return. The main facets of the outer skin are separately fastened to a rather complex skeletal frame. Since the accurate shaping and placement of these facets is critical to achieving a low radar cross section RCS , production tooling had to be ten times more precise than the tooling used to build conventional aircraft.

The exact composition of the RAM is classified, but it is believed to consist of a matrix of magnetic iron particles held in place by a polymer binder. Originally, RAM came in large flexible sheets, and was bonded to a metal wire mesh, which was in turn glued to the airframe of the FA. Later, when the aircraft entered service, the Air Force built a special facility for the application of the RAM.

In order to provide for uniform and accurate application, as well as to prevent people from coming into contact with the highly toxic solvents which make the RAM liquid, the process is completely automated. Minor touch-up s are made in the field using a hand-held spray gun. They are housed in broad nacelles attached to the sides of the angular fuselage. The General Electric turbofans are fed by a pair of air intakes one on each side of the fuselage. Two gratings with rectangular openings cover each intake.

The purpose of these gratings is to prevent radar waves from traveling down the intake ducts and reaching the whirling blades of the turbofans, which would tend to produce large echoes. This works because the spacings between the grids on the grating are smaller than the wavelengths of most radars. The grating is covered with RAM, which helps reduce the reflections even further. The small fraction of incident radar energy which does pass through the grating is absorbed by RAM mounted inside the duct. Unfortunately, these gratings also restrict airflow to the engines, so a Large blow-in door is fitted atop each engine nacelle to increase airflow to the engine during taxiing, takeoffs, or low-speed flight.

Ice buildup on the intake gratings is a persistent problem, which tends to clog the rectangular openings and restricts the airflow even further. In order to clear the ice, the Femploys a electrical heating system to remove ice during flight.

Stealth turns 40: Looking back at the first flight of Have Blue

A light on either side of the fuselage illuminates the intake covers, enabling the pilot to watch the deicing operation during night flights. One of the more unusual aspects of the F is its engine exhaust system. Like the air inlets, the exhaust outlets are mounted atop the wing chord plane, one on each side of the centerline. The engine exhausts are narrow and wide and are designed to present as low an infrared signature as possible and mask the rear of the engine from radar illumination from the back.

The exhaust ducts are round at the rear of the turbofans, but are flattened out and become flume-like by the time that they reach the front of the narrow slotted exhaust outlets at the rear of the fuselage. At the end of each of the narrow slotted exhaust ducts, there are twelve grated openings, each being about six inches square.

These grated openings help reduce unwanted radar reflection from the rear as well as providing additional structural strength to the exhaust ducts. The exhaust gratings are shielded from the rear and from the bottom by the F's platypus-bill-shaped rear fuselage section. The extreme rear edge of the aircraft behind the exhaust slot is covered with heat-reflecting tiles.

These ceramic tiles help to keep the rear of the aircraft cool, since they tend to reflect the infrared radiation emitted from the exhaust, rather than absorbing it as metals tend to do. The bypass air from the engine is also used to help cool down the entire metal structure of the rear of the aircraft. The exhaust system is complex, incorporating sliding elements and quartz tiles to accommodate heat expansion without changing shape. Although the system works fairly well, Lockheed has reported that the design of this exhaust system was the single most difficult item in the entire FA project.

A typical fighter has a head-on RCS of about five square meters, which is technical language for saying that it seems as large on radar as a perfectly-reflective sphere of the same cross-sectional area. However, if critical flat surfaces or whirling turbine blades happen to be exposed to the radar, the RCS can be much larger. Reportedly, the combination of faceting and the application of RAM gives theFA an effective radar cross section of somewhere between 0.

This means that a typical radar will not be able to detect an FA at a range any greater than miles. Directional stability and control of the FA is provided by a pair of all-flying tails mounted on the aircraft's central spine and oriented in a V arrangement, reminiscent of the tail of the Beechcraft Bonanza.

Unlike most V-tails, however, they have no pitch-control function. Each vertical tail consists of a fixed stub, and an all-flying rudder which pivots around a fixed shaft. The hinge line between stub and moveable tail is Z-shaped rather than straight, in accord with the stealth principle of the avoidance of any straight edges. Both the fixed stub and the all-flying rudder are faceted to further reduce radar reflectivity.

On the Have Blue test aircraft, the vertical tails were mounted further outboard on the wings and were canted inward rather than outward. The purpose of the inward-canted vertical tails on the Have Blue was to shield the upward-facing platypus exhaust nozzles from infrared detectors above the aircraft.

In practice, however, these tails tended to act as reflectors for infrared radiation, bouncing the rays toward the ground and making the aircraft more visible from below. Originally, the basic stealth design philosophy was to have the lowest observability from the bottom and from the front, with the upper hemisphere having less stringent requirements. Consequently, on the FA aircraft, the tails were moved back further on the fuselage so that they are no longer directly over the exhaust.

In addition, the Have Blue tails were in effect mounted on twin booms which was a structurally inefficient arrangement. The leading edge wing sweep on the Have Blue was To improve the performance, the wing sweep was reduced to The flying surfaces on the FA consist of four elevons on the wing trailing edge two inboard and two outboard and two all-flying rudders mounted in a V arrangement on the rear fuselage. The elevons and the rudder are all faceted to reduce their radar signature, and the hinge lines between the wings and the elevons sealed with flexible RAM.

The four elevons can deflect upward or downward by 60 degrees, and the rudders can deflect 30 degrees left or right. The elevons act in the pitch and roll axes, where as the rudders act in the yaw axis. The angle of attack during landing is about 9 degrees. The elevons do not double as flaps, which makes the landing speed of the FA rather high.

The FA replaced this windshield with a center flat panel since a heads-up display would not work very well with a center bow blocking the view. This resulted in a change in the shape of the nose to a steep downward-sloping section for good downward visibility with a sharp, pyramidal-shaped nose cap for aerodynamics and stealth.

This change made the F slightly more observable by radar than the Have Blue. The cockpit of the Fis covered by a large and heavy hood-like canopy with five separate flat transparencies one on either side and three in front. The visibility from the cockpit is rather limited upward, downward, and to the rear.

The canopy opens to the rear and has serrated edges in order to limit the radar reflectivity of the joint between canopy and fuselage when the canopy is closed. The five flat transparent panels are specially treated to further reduce the aircraft's RCS. The windshield is coated with a special gold film layer to prevent the pilot's helmet from being detected by radar. This was found to be an important problem during early tests.

The FA, like the Have Blue before it, is unstable about all three axes and requires a fly-by-wire system in order to be able to fly at all. The fly-by-wire system is similar to that in the F, and is quadruply redundant. There are four independent channels which each control the same function. The signals from each of the channels are constantly being compared with each other, and if one signal is found to differ from the other three, its channel is assumed to have failed and is automatically shutdown.

In the unlikely event that all four channels manage to fail at the same time, the aircraft cannot be flown and the pilot would be forced to eject. Since the aircraft cannot use any sort of radar navigation system, the fly-by-wire system relies on information about airspeed and angle of attack from four individual static pitot probes of diamond section with pyramid-like tips mounted in the extreme nose.

Each of the four-sided pitot heads have tiny holes on each facet, and differential readings from each hole provide air speed, pitch and yaw information to the flight control system.

The design of these four nose sensors, plus the requirement that they not produce any unwanted radar reflections, was one of the more difficult engineering problems the Lockheed team had to solve. The FA also differed from the Have Blue in having a weapons bay. Since external hard points for bombs or fuel tanks are taboo for a stealth attack aircraft, all stores must be carried internally.

The weapons bay is located in the belly on the centerline. It has two wells, each covered by an inboard-opening door. The outer edges of the weapons bay doors have serrated edges that are designed to reduce the radar reflection from the joint between the doors and the fuselage belly. The weapons bay can accompany up to pounds of ordinance pounds in each well.

Lockheed Have Blue - Wikipedia

The GBU Paveway II laser-guided bomb consists of a special nose and tail section attached to a standard pound Mk 84 high-explosive bomb. The tail section of the bomb consists of a set of folding aerodynamic surfaces which permit the bomb to glide, whereas the nose section includes a laser light seeker, guidance electronics, and control fins.

The GBU Paveway III is a more advanced version of the Paveway II with a larger tail surface and a more efficient guidance system which permits it to be used at lower altitudes and at greater distances from the target. The BLU deep-penetration bomb has a forged casing of hardened steel which permits it to pierce more six feet of reinforced concrete before exploding. When dropped on softer targets, theBLU can bury itself deep into the ground before exploding, destroying its target by sending earthquake-like shock waves rippling through the ground.

The FA canal so carry up to two Mark 61 nuclear weapons, although the aircraft does not actually have an assigned nuclear mission. For long-range ferry flights, fuel tanks can be installed in the weapons bays in the place of bombs. The FA has no air-to-air capability, or at least none that has been announced to the general public. It has no radar, it does not carry an internal cannon, and is not equipped to carry or launch air-to-air missiles. The FA can in principle launch an infrared homer, provided the missile can be dropped from an extendable rack so that its seeker could acquire the target before launch.

The FA cannot rely on radar for navigation, weapons aiming, or weapons delivery because the transmission of a radar signal would tend to give away the location of the aircraft and hence defeat the whole purpose of stealth. Both systems are built by Texas Instruments. The FLIR is mounted in a recess just ahead of the cockpit front windshield.

It is located in a steerable turret containing a dual field of view sensor. When not in use, the FLIR is rotated degrees to keep prevent debris damaging the sensor. The DLIR sensor system is located in a recess mounted underneath the forward fuselage and to the right of the nose landing gear well.

The edges of the recesses are serrated, with fasteners covered with RAM putty. The DLIR is provided with a bore-sighted laser for illuminating the target for attack by laser-guided weapons.

The forerunner of the F-117 Stealth Fighter flew for the first time 40 years ago this month.

The spot size of the laser on the ground is about inches, and the spot is stabilized in position by the IRADS. This system uses an electrostatically-suspended gyro as the primary means of guidance. As the aircraft approaches the target, the pilot monitors the view presented by the FLIR on the heads-up display screen. When the specific target is identified, the pilot switches to the narrow view on the FLIR, and locks the screen of the display onto the target.

As the target disappears underneath the aircraft, control is handed over to the DLIR, which acquires the target and continues to track it. When the pilot decides to attack, he releases a laser-guided Paveway bomb. Approximately 7 to 10 seconds before bomb impact, the DLIR's laser is turned on and illuminates the target, and the bomb homes onto the reflected infrared laser light reflected from the target. A parachute braking system is provided, since the lack of flaps makes the landing speed quite high knots, or mph.

The braking parachute is housed behind split doors atop the rear fuselage. The braking chute is deployed as soon as the nose wheel makes contact with the runway. The parachute can also double as an emergency antispin device if needed. An in-flight refueling receptacle is added behind the pilot's cockpit. A small light is mounted near the receptacle to guide the refueling boom operator in nighttime refueling operations. Midair refueling is one of the more difficult aspects of FA flight, since it is always done at night and the FA pilot's upward vision is blocked by the canopy so that he cannot actually see the boom of the refueling aircraft.

The landing gear is of the standard tricycle type, with single wheels and tires that retract forward. The landing gear doors have serrated edges that help to reduce the radar cross section. A set of retractable communications antenna are fitted to the upper fuselage just behind the pilot.

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