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Tacit Blue
Tacit Blue and its influence on future US UAV programs:
America’s “stealth revolution” took place in the mid 1970′s, spawned by advances in computer processing and aircraft manufacturing techniques, as well as the ongoing Cold War. By the turn of decade multiple “low observable” programs, spearheaded by a variety of manufacturers, were well underway. Most notable of all of these programs was Lockheed’s notorious bleeding edge “Skunkworks” design house’s “Have Blue” demonstrator, aka the “Hopeless Diamond.” The successful Have Blue program would eventually morph into the world’s first true “Stealth” production aircraft, the infamous F-117A Nighthawk Stealth Fighter (the Nighthawk was really an attack aircraft but marketing is a powerful thing even in the Pentagon’s black budget world). Yet another smaller, less glamorous, but arguably as influential top-secret technology demonstration was also underway around this same period in time, known ambiguously as “Tacit Blue.”
The Tacit Blue aircraft, known affectionately as “The Whale” amongst those who were involved with the program over at legendary aerospace manufacturer Northrop, had an entirely separate set of objectives than Lockheed’s proposed stealth attack aircraft, although radar invisibility was one they both had in common. Whereas Lockheed, leveraging its innovative “ECHO1″ radar predictability software, found the “faceted,” diamond like structural approach suitable for a stealth tactical attack aircraft, where speed and agility were on the requirement list, a few years later Northrop would take an almost entirely opposite route to achieve groundbreaking “low observable” results.
In the late 1970′s the DoD’s Defense Advanced Research Projects Agency (DARPA) was working hard at breaking open stealth technology’s virtual “Pandora’s box,” and diligently figuring out new ways to leverage the still very young and emerging capability. Never before could Americaactually build an invisible warplane, and the creative minds over at the Pentagon were deciding exactly where this new revolutionary method of designing aircraft could make the most impact. One of the areas where they wanted to push the stealth envelope was in the business of battlefield reconnaissance. At the time, tactical aerial intelligence was collected via fighter jets, or other very un-stealthy aircraft, that were fitted with cameras and sent out to make daring runs, sometimes at very low-level and at very high speeds, over enemy territory. At best these systems could capture a snapshot in time of the enemies force posture, which could never be exploited in real-time, and was only gained at incredible risk to the aircrews involved. Other strategic surveillance assets, such as the SR-71 Blackbird and especially reconnaissance satellites had similar, if not even more severe drawbacks, as the information they gathered was momentary in nature, and resolutions were at times inconsistent. With these limitations in mind, DARPA hired the Northrop company to answer a simple question: Could emerging “low observable” aircraft technology be used to build an aircraft that could survive while loitering for hours at a time deep behind enemy lines, all the while collecting real-time battlefield tactical intelligence that commanders could exploit in real-time, while being located safely behind friendly lines?
During this same period of time the USAF was looking to develop an aircraft that could take advantage of recent air to ground radar technology revelations. The concept behind such emerging capabilities was to use a large phased array radar, mounted on an airplane, to provide real-time Ground Moving Target Indicator (GMTI) intelligence. GMTI is a radar mode that basically sees the movement of vehicles across large land masses, as well an associated Synthetic Aperture Radar (SAR) mode that could theoretically map the battlefield using high-resolution radar beams and computer processing instead of optical photography. Both modes are able to peer through inclement weather with ease, can be implemented at long-range, and are persistent in nature. In other words, they can be used to survey enemy territory for long periods of time, looking for not just targets but operational trends in the enemy’s force posture, under almost any conditions. This new radar technology development program was known as “Pave Mover,” and it would prove to have drastic effects on the future of airborne intelligence collection.
With the “Pave Mover” radar concept and Northrop’s stealthy and persistent tactical intelligence aircraft in mind, the folks at DARPA decided to combine the two into a top-secret program now known officially as the Battlefield Surveillance Aircraft-Experimental (BSAX), code name “Tacit Blue.” By combining the deep penetrating radar capabilities of “Pave Mover” and Northrop’s stealthy surveillance platform, commanders would theoretically be able to look deeper into enemy territory than ever previously imagined, and the products of such a capability could truly be war winning. The only problem would be, how would Northrop engineers leverage a new design philosophy that was still in its infancy to be able to carry a massive radar array while staying invisible to radar at the same time? Further, how would they ensure that the radar itself was not detected through its high power emissions? The program’s goals were truly groundbreaking and in being so they were also incredibly challenging. Literally, the BSAX had to not just blaze a single trail, but many in order to be successful.
Around the turn of the decade, Northrop had designed an aircraft that was so ugly that it had to be genius, and it was. Resembling a whale, including its blow-hole on top (the jet air intake!) the Tacit Blue was a marvel of function over form. Instead of using the faceted, almost diamond like approach to designing their stealth aircraft, as Lockheed had done a couple of years prior, Northrop engineers took a different approach, one of continuous curvatures, chined edges, and masked vulnerabilities. Much of this design philosophy was demanded by the “loiter” part of Tacit Blue’s mission requirements. The aircraft had to feature “all aspect stealth,” whereas an aircraft like the F-117 could be optimized for front and rear, or “coming and going” stealth aspects, as their mission was sneak inside a defense network, drop bombs, and high tail it out of danger. Tacit Blue had no such luxury as it would have to loiter for hours over enemy territory, and thus every angle would be susceptible to radar surveillance for prolonged periods of time. Tacit Blue’s rounded approach to stealth, known as curvilinear design, would be a massive development that would affect future stealth technology arguably more than the famous F-117′s “faceted” approach to masking radar signatures.
The Tacit Blue Weighed in at some 30,000lbs, measured around 55′X55′ and looking more like a motor-home than an aircraft. With a massive phased array radar, provided by Hughes, shoehorned into its boxcar fuselage, the ugly Whale was one unaerodynamic flying creature. It’s surfaces were so smooth that it almost took on a sculpted appearance. This does make some sense as one of its main designers actually sculpted its unique fascia while sitting on a park bench after being stumped on how to come up with a solution for DARPA’s BSAX challenge. By its very nature, Tacit Blue was a highly unstable design and thus had to utilize an advanced fly-wire-system similar to the one used on YF-16. Making the aircraft even more awkward, the design team utilized many parts from existing aircraft to minimize design time, complexity and cost. At a price tag of about $130,000,000 to build, with a total program cost of about $170,000,000, the Whale was an expensive ugly duckling, but it would pay for itself in spades over some 135 test flights between 1983 and 1985.
During these 135 test flights Tacit Blue and the whole BSAX team would not only pave the way for a multitude of stealth and surveillance technologies, but in doing so it would make the exact case for a TIER3- unmanned stealth and persistent tactical reconnaissance requirement that would spawn the RQ-3 Darkstar some ten years later, and eventually the RQ-170 another decade after that. In many ways Tacit Blue was the manned experimental RQ-170 of decades past. Here are some of the key BSAX program’s accomplishments:
1.) “Curvilinear” and “All-Aspect” Stealth- Tacit Blue’s design was incredibly unique for its time, and many, if not all of its features can be seen today on modern stealth aircraft and UAVs. Its continuously curving architecture was revolutionary and would pave the way and help validate the design for Northrop’s B-2A Bomber, still America’s most valuable (that we know of) deep penetrating weapon system some 20+ years after it’s unveiling. Also, the “Whale’s” exact design was almost exactly copied for the Tri-Service Standoff Attack Missile (TSSAM), although the program was cancelled in 1993 due to budget and technological reasons, similarities are still abundant on the JASSM missile system currently in service. Its chined forward fuselage bears a close family resemblance to that seen on the YF-23, and it’s elliptical exhaust can be identified on the RQ-170 Sentinel. It’s overhead stealthy jet inlet, and deep buried motors are both concepts utilized to a great degree on the B-2 and RQ-170 as well.
Tacit Blue’s “all aspect” stealth design philosophy has been used in almost every low observable product in existence today and can be seen extrapolated to a greater, more refined degree on the f-22 and F-35. In fact the “curvilinear” design method, aided by much more powerful computer aided design software and processors, would allow stealth aircraft to be configured more freely for many different kinds of missions and uses as compared to the F-117′s inefficient and limiting faceted architecture. Although the Tacit Blue’s design was so ahead of its time it seems as if it is still being used today with minimal modifications. Case in point is General Atomics’s new Predator C, also known as the Avenger, which possesses and uncanny resemblance to Tacit Blue some 25 years after its last flight. In summary, structurally alone, the Tacit Blue changed the way America builds aerial weaponry forever, arguably more so than the more popular “Have Blue” demonstrator and it’s infamous F-117 successor.
2.) Infra Red Heat, Noise, and Optical Signature Reduction- It is said that the Tacit Blue was literally the coolest aircraft ever tested at the time. The aircraft ejected its exhaust before and above the end of aircraft’s tail section. This made the motor’s direct heat signature masked to anyone viewing the aircraft from below. It is also said that Tacit Blue’s exhaust was “after cooled” or chilled after being ejected from the aircraft’s engine, and this, combined with chemicals injected into the exhaust, all but eliminated the possibility of creating a contrail or being detected with infra-red sensors. Further, its light paint was optimized for medium and high altitude operations during daytime, and its deeply buried motors made the aircraft incredibly quiet. All of this and of course the unlikely overall shape of the Tacit Blue would make the aircraft almost entirely undetectable. These low-signature revelations would be exploited in advanced military aircraft design for decades after the Whale’s last flight.
3.) Low Probability Of Intercept (LPI) Radar- The Tacit Blue’s design was extremely stealthy, but packing a huge radar that emits tremendous amounts of energy over or near an enemy battlefield is not stealthy to say the least. Passive detection devices and Electronic Support Measures (ESM) could alert the enemy to the BSAX’s whereabouts almost as easily as radar detection if it’s radar were to be employed in a normal fashion. So engineers from Hughes and Northrop worked on cutting-edge ideas to make what was already a breakthrough radar technology, that being Ground Moving Target Indicator (GMTI) capability, all that more revolutionary by making its electronic emissions almost impossible to detect by the enemy.
LPI radar works using a variety of tactics that combine collectively to lower the possibility of a radar being detected while turned on. Advanced methods such as utilizing agile frequency modulation over a very wide band, emitting a much more finely tuned beam at lower power for short bursts instead of long continuous emissions, all via a phased array radar design that is paired with advanced back-end computing power fantastically lowered the chances of the Tacit Blue being detected via its emissions. Today LPI radar techniques, especially when joined with new Active Electronically Scanned Array (AESA) radar sets has changed the way radar is used in aerial and sea combat. The technology was most certainly used in the ATB program which produced the B-2A Spirit that was fielded just a few years after the Whale made its last flight. At the time the B-2 was a fantastic asset to migrate LPI airborne radar technology into because it had massive real estate on it’s leading edge for a pair phased array radar arrays to be installed, and it could utilize them while under it’s stealth cloak. Today, stealth fighters like the F-22 and F-35, and even modern combat ships use advanced LPI radars to their advantage, allowing them to keep tabs and engage their enemies while maintaining a high degree of invisibility. Further, the exact LPI and GMTI technology pioneered by Tacit Blue, improved and miniaturized over time, most likely makes it possible for the stealthy RQ-170 Sentinel to penetrate deep into enemy territory and actively gather high-resolution radar intelligence without being detected. This has been further confirmed by Pentagon officials in a recent piece posted over at Aviation Week where sources said that the RQ-170 started out as a radar platform and then was refitted for electre-optical streaming video as well a few years back.
4.) Data Links: Unlike Tacit Blue’s larger, standoff oriented successor, the Boeing 707 based E-8 J-STARS, which emerged as the chosen production platform as a result of the multi-tiered “Pave Mover” demonstration program, Tacit Blue had no radar and intelligence support operators on-board. Seeing how the requirement for real-time intelligence was a key part of the “Pave Mover” program and thus the BSAX program, engineers had to figure out a way to not only control the radar but also broadcast the stealthy Tacit Blue’s intelligence data back to operators on the ground for immediate exploitation. This was a massive departure from airborne intelligence collection of the day, which either saw large airframes utilized so that operators on-board could control the surveillance systems and utilize the information collected, or smaller airframes would be utilized to go out and collect intelligence that could only be leveraged once deciphered by specialists well after the mission ended. The incredibly high-risk nature of a deep penetrating, loitering, airborne surveillance platform’s mission set could be somewhat offset by relocating the radar operators and intelligence professionals off the aircraft and far behind friendly lines. These operators would be connected to the small stealthy airframe via a data link. Without breakthroughs data link technology Tacit Blue’s objectives would have been virtually impossible to achieve.
Tacit Blue used line of sight data links that were also low probability of intercept in nature and thus difficult to detect by the enemy. All the data collected over “enemy” territory was transferred back to the control station it was “tethered to,” theoretically far away from the front lines of the battlefield. At the time data links were used mainly between air superiority fighters to sort targets and to provide other situational awareness functions that would help crews be less reliant on radio communications, or in TV guided weaponry like the “Popeye” series of missiles.Tacit Blue stepped way beyond this capability and truly blazed the way for modern UAV technology and their related ground control and information exploitation concepts as we know them today. Most notably those used to satisfy the TIER2+ (which became the RQ-4 Global Hawk) and TIER3- (which became the RQ-3 Darkstar) requirements put forth by the USAF almost a decade after the Tacit Blue took its last flight. Today, data links, and LPI optimized data links, are used in almost every combat aircraft flying in the US’s inventory. These links primarily exist in the form of the Multifunctional Information Distribution System (MIDS)/Link-16 architecture. Further, a new data link optimized for stealth aircraft, which utilizes cutting edge LPI technology, is currently under development. This system is known as Multifunctional Advanced Data Link (MADL) which will be fielded on America’s stealth F-22, B-2, F-35 and Next Generation Bomber force. Modern data links have been described as the most game changing weapon system of the 21st century, and offer a single pilot a gods eye view of battlefield around him, with massive amounts of data being fused into a single tactical picture right at his or her fingertips. Never before has such a widespread capability existed, and it is arguably the most significant “force multiplier” concept combat aircraft have seen for decades.
5.) Ground Moving Target Indicators (GMTI) Radar Technology: As the deeply classified arm of the “Pave Mover” program, the Whale proved that such technology could be shoehorned into a relatively small tactical asset, when paired with a tethered ground station, and this aircraft could also be invisible to radar, loiter for hours in denied air space, peering deeper into enemy territory than a standoff asset could, literally into a foe’s vulnerable rear echelons. The testing done with Tacit Blue no doubt added greatly to the E-8 J-STARS program, and was further leveraged in the RQ-4 Global Hawk over a decade later, of which GMTI capability was one of the main capability requirements. It is also widely speculated that the RQ-170′s original mission was to provide high resolution Synthetic Aperture Radar (SAR) pictures and possibly GMTI data back to commanders on the ground to be used in real time. GMTI is not only effective at tracking armored columns, but it is also effective at cataloging critical “pattern of life” intelligence data in and around a target area. Since Tacit Blue flew with it’s mini-van sized Sideways Looking Aerial Radar (SLAR), such radar technology has been miniaturized to a massive degree. These radars can now be packed inside the dimensions of a targeting pod, while offering much more capability, and have become ideal for UAV operations.
6.) Dual-Role, Stealthy Electronic Intelligence (ELINT) Concept: Although the Tacit Blue may never have flown with passive ELINT hardware on-board, those involved with the program have made it clear that they were very aware of the “Whale’s” unique potential for carrying automated electronic listening equipment to passively collect the enemy’s electronic order of battle and their communications without them ever knowing. This ELINT suite of equipment could be manipulated and it’s products exploited in real-time by the ground control station just like the radar array. This information could then be used to great effect for Suppression of Enemy Air Defenses (SEAD) and general intelligence purposes. In other words, Tacit Blue could provide similar functions as the much larger, standoff in nature RC-135 “Rivet Joint,” as a secondary mission while conducting radar surveillance. Since the aircraft was already being theoretically risked over enemy territory it was only logical that such a risk be leveraged to its maximum potential in order to gain the maximum amount of rewards. This “cherry on top” added capability is very similar to what we know about the F-22 and it’s ALR-94 ESM kit, which some say is the most potent part of the Raptor weapon system, and supports what many hypothesize about the RQ-170, that it has a secondary ELINT capability built-in.
7.) Advanced Fly-By-Wire: The malformed Tacit Blue was unstable in both pitch and yaw and depended on a quadruple redundant fly-by-wire system in order to literally keep its nose pointed in the right direction. The aircraft was proven to flip on its back and weather-vein tail first into the airstream during wind tunnel tests! It has been said that the Whale was the most unstable aircraft mankind had ever flown at the time, a situation fraught with danger and pitfalls. Yet engineers were able to refine the flight control system enough so that the aircraft would fly reliably, although it was in no way a hot rod or high-performance machine. Lessons learned during the design and implementation of the “Whale’s” flight control system would be used later on as aircraft designs became more function over form. Thus opening up the opportunity to fly aircraft of strange, inherently unstable shapes, such as the B-2 flying wing bomber, and later the RQ-170 Sentinel. In the end, and against great odds, Northrop built an invisible sensor truck, and a flyable one at that.
As you read through the incredible accomplishments of the Tacit Blue / Whale / BSAX or whatever you want to call it, there can be little doubt that this aircraft was the progenitor of the TIER3- program, and thus the RQ-170 Sentinel as we know it today. The BSAX program definitively marks the first time in aerospace history where such a concept was envisioned, tested and validated. Additionally, as part of the decision to fund the Tacit Blue program, the USAF had a strong interest in utilizing the technology for an unmanned aircraft, a concept that was really beginning to emerge as the possible future of air combat at the time. Tacit Blue’s mission, persistent tactical reconnaissance over enemy airspace, is a very risky one. By taking human risk out of the equation the concept could be more readily applied during a time of conflict and the USAF knew this, although the technology to make such a capability reality simply did not exist at the time.
Almost everything we know about the TIER3- program that emerged in the mid 1990′s and the subsequent RQ-170 Sentinel that sprang from its ashes can be traced directly to Tacit Blue. It’s curvilinear low observable design was utilized extensively on the B-2 and can be seen leveraged to even a greater degree on the RQ-170. The same can be said for the RQ-170′s overhead inlet, deep buried motor and light paint optimized for daytime operation. Even the exhaust of the RQ-170 matches that of the Whale’s to an uncanny degree. Then there is the Tacit Blue’s data link systems, cutting edge at the time, that now represents the genesis of all unmanned aerial vehicles control interfaces. In effect the offspring of the Tacit Blue’s ground control stations and data links would make the unmanned aircraft concept as we know it today actually feasible. By the 1990′s breakthroughs in computer automation and satellite communications would let unmanned aircraft dream become a reality.
Low probability Of intercept surveillance radar and advance data links would make it so the RQ-170 could penetrate deep into enemy airspace and operate for hours without a high risk of being detected by passive listening systems. Even the proposed secondary ELINT capability of the BSAX is almost certainly on-board the RQ-170. Beyond logical deduction there were multiple reports from sources in the Pentagon that the RQ-170 not only transmitted real-time video on the night of the Bin Laden raid but that it was also providing key ELINT information so that commanders could monitor the Pakistani’s response, or lack thereof, at critical times during the fragile operation. Even the concept of using an aircraft as a sensor platform only, and communicating its collected data back to a ground station in real-time for interpretation, was the forerunner of the RQ-170′s real-time tactical reconnaissance capabilities.
The definitive proof that establishes a direct ancestral link between Tacit Blue and the RQ-170 Sentinel can be found in the very reason why the BSAX was created in the first place, to prove that a small stealthy tactical intelligence platform could loiter for long periods of time over denied airspace undetected, all the while transmitting its high fidelity intelligence back to commanders on the ground in real-time. Does this sound familiar? Of course it does, as this is the exact same unique mission requirements as the unmanned TIER3- concept that emerged almost a decade after the Whale’s last flight. Further, the BSAX was really a minimally manned asset, the pilot providing the flight control only because remote systems were simply incapable of doing so at the time, and were not needed in order to prove the concept during controlled tests. So although the larger 707 based E-8 J-STARS become the known winner of the “Pave Mover” program, the idea of a stealthy and persistent tactical surveillance aircraft was proven by Tacit Blue with flying colors. Further, it was realized that by simply replacing Tacit Blue’s radar, or in addition to it adding advanced imaging equipment, you would have an asset that would be almost entirely undetectable and capable of collecting multiple forms of intelligence during its high risk missions.
It would take a decade for satellite data links and computer hardware to catch up with the BSAX in order to make the concept an unmanned reality. Even the TIER3- requirement of the early 1990′s stated the need to leverage miniaturized LPI radars as part of the program, along with fully passive electro-optical surveillance payloads. And from the TIER3- minus requirement, and the program’s resulting RQ-3 Darkstar, the RQ-170 Sentinel was born, as was detailed in my prior piece linked above. So the Sentinel’s direct lineage, its exact reason for existing, dates back some 30 years to the birth of the BSAX program and Tacit Blue.
In the end the RQ-170′s pedigree is a long one of secret successes and public failures, culminating in a drone so effective and so critical to national security that it was used on the most sensitive American mission since the Doolittle Raid on Japan at the beginning of WWII. The fantastically successful Tacit Blue demonstrator, the clear father of the troubled Darkstar, the grandfather of the history making Sentinel, and the uncle of so many other successful aircraft that used smaller parts of its innovative technologies to accomplish their own diverse missions, leaves a legacy that is truly stunning. Yet one question does emerge out of this epic family saga: After learning so much about the success of the Tacit Blue, did this aircraft and it’s mission set in fact go the way of the RQ-3 Darkstar, being evolved into a more operational form under a dark classified cloak? Even the Tacit blue took over a decade from its last flight to become partially declassified. What is to say that a follow-on, much more capable system was not fielded once the BSAX technology demonstration program shutdown? Just as the standoff oriented “TIER2+” RQ-4 Global Hawk was pursued in the white world and the “TIER3-” RQ-170 was pursued in the black, maybe the similarly standoff oriented E-8 J-STARS and a stealthy tactical Tacit Blue follow-on blazed a similar path? Isn’t this more probable than not when compared to historical patterns of evolution regarding such programs and game changing capabilities?
Was Tacit Blue’s first actual offspring the fabled manned TR-3A “Black Manta” that was spotted around the globe, supposedly assisted the F-117A over Baghdad, and possibly crashed at Royal Air Force Base Boscombe Down in the 1994, or an aircraft similar to it? Only a couple of months after this mysterious crash at Boscombe Down of an aircraft that fits the proposed tactical manned stealth reconnaissance aircraft mold, the SR-71 program was reactivated against huge odds. Regardless of any speculative details it just seems somewhat apparent there may in fact be a manned missing linkin the RQ-170′s murky family tree. Something existing between the Tacit Blue technology demonstrator and the TIER3- unmanned requirement of the mid 1990′s seems like almost a given considering the historic continuity of such programs. Or are we really to believe that the USAF, after the conclusion of the Tacit Blue program, with such an innovative and proven tactical battlefield intelligence technology in hand, decided not to pursue a follow-on in any form until the curious announcement of the TIER3- program that resulted in the still-birth of Darkstar in the mid 1990′s? Was there really no aircraft to fill this role, even in very small numbers, between the triumphant Tacit Blue’s last flight, and the far-reaching unmanned TIER3- program? Would the existence of such a craft in fact also provide an answer to the odd SR-71 Blackbird retirement initiative of the late 1980′s?
The SR-71 was designed during a time when true stealth was a pipe-dream and thus it had to leverage high altitudes, great speed, and some rudimentary low observable techniques to survive. It would make sense that once the proverbial stealth genie was out of the bottle there would be no need for hugely expensive ultra high-speed reconnaissance over enemy territory. In fact a theoretical aircraft like the TR-3A that utilized subsonic, and/or moderate super-cruise operating speeds while at medium altitudes, and offered near radar invisibility, could actually possess an advantage over one that utilized blistering high speeds and altitudes. Slower speeds would give the platform more time to soak up intelligence data while remaining undetected, and if need be, like the Tacit Blue, it could loiter for long periods of time over denied territory. Did this reasonably faster, more capable and survivable offspring of Tacit Blue nicely fill the gap, along with modern strategic satellite reconnaissance, left by the retirement of the SR-71 Blackbird? One that not only inhabited Tacit Blue’s unique mission set and exploited it’s groundbreaking innovations, but also one that incorporated some of the innovations applied to the B-2 bomber, and the technologies that were publicly showcased during the Advanced Tactical Fighter (ATF) program in the form of the YF-23, although a few years prior, while they were still under a dark shroud of secrecy? Was this in fact Northrop’s ASTRA (Advanced Stealth Reconnaissance Aircraft) that was rumored to exist during the time period in question? It sure makes a lot more sense than the almost mainstream obsession with the possible existence of the “Aurora” high-speed, high altitude spy plane, that would have been unbelievably expensive to develop and operate, while only furnishing similar capabilities than those of spy satellites that the DoD and US intelligence apparatus has already invested in heavily.
If you asked me my opinion on this a month ago I would have said it would be anyone’s guess, but after the hours of research on the RQ-170′s lineage, it would appear that there is indeed an aircraft flagrantly missing from its family tree. Some 10+ years would have gone by between the time that this invaluable capability was proven and when we would see a publicrequirement from the USAF to fill such a role in the guise of the unmanned TIER3- program. But was the TIER3- the first attempt at an operational stealth tactical reconnaissance capability, or was it set in place to replace an aircraft that already existed, its main weakness being that human beings were at risk in the cockpit?
I believe that the BSAX did in fact result in a semi-operational manned airframe of a different configuration, but one of the exact same mission, that leveraged both Tacit Blue, and it’s emerging B-2 cousin’s technology innovations. Such an aircraft would help more evenly fill the gap left by the aging and vulnerable SR-71s on a tactical level, leaving satellites for the strategic reconnaissance mission. Theorizing freely, possibly this program never reached its full potential and was abandoned after a fatal crash at RAF Boscombe Down in 1994, thus ushering in the Blackbird as a stopgap and the TIER3- as a final replacement.
Like so many things that prowl the skies high above the central Nevada desert, we may never truly know their whole story, although we can apply logic, patterns in aerospace development, known facts and liberal creativity to create a story that is more probable than possible, and probably more believable than the actual truth….
Predator C
RQ-180 under construction
Tacit Blue
Tacit Blue and its influence on future US UAV programs:
America’s “stealth revolution” took place in the mid 1970′s, spawned by advances in computer processing and aircraft manufacturing techniques, as well as the ongoing Cold War. By the turn of decade multiple “low observable” programs, spearheaded by a variety of manufacturers, were well underway. Most notable of all of these programs was Lockheed’s notorious bleeding edge “Skunkworks” design house’s “Have Blue” demonstrator, aka the “Hopeless Diamond.” The successful Have Blue program would eventually morph into the world’s first true “Stealth” production aircraft, the infamous F-117A Nighthawk Stealth Fighter (the Nighthawk was really an attack aircraft but marketing is a powerful thing even in the Pentagon’s black budget world). Yet another smaller, less glamorous, but arguably as influential top-secret technology demonstration was also underway around this same period in time, known ambiguously as “Tacit Blue.”
The Tacit Blue aircraft, known affectionately as “The Whale” amongst those who were involved with the program over at legendary aerospace manufacturer Northrop, had an entirely separate set of objectives than Lockheed’s proposed stealth attack aircraft, although radar invisibility was one they both had in common. Whereas Lockheed, leveraging its innovative “ECHO1″ radar predictability software, found the “faceted,” diamond like structural approach suitable for a stealth tactical attack aircraft, where speed and agility were on the requirement list, a few years later Northrop would take an almost entirely opposite route to achieve groundbreaking “low observable” results.
In the late 1970′s the DoD’s Defense Advanced Research Projects Agency (DARPA) was working hard at breaking open stealth technology’s virtual “Pandora’s box,” and diligently figuring out new ways to leverage the still very young and emerging capability. Never before could Americaactually build an invisible warplane, and the creative minds over at the Pentagon were deciding exactly where this new revolutionary method of designing aircraft could make the most impact. One of the areas where they wanted to push the stealth envelope was in the business of battlefield reconnaissance. At the time, tactical aerial intelligence was collected via fighter jets, or other very un-stealthy aircraft, that were fitted with cameras and sent out to make daring runs, sometimes at very low-level and at very high speeds, over enemy territory. At best these systems could capture a snapshot in time of the enemies force posture, which could never be exploited in real-time, and was only gained at incredible risk to the aircrews involved. Other strategic surveillance assets, such as the SR-71 Blackbird and especially reconnaissance satellites had similar, if not even more severe drawbacks, as the information they gathered was momentary in nature, and resolutions were at times inconsistent. With these limitations in mind, DARPA hired the Northrop company to answer a simple question: Could emerging “low observable” aircraft technology be used to build an aircraft that could survive while loitering for hours at a time deep behind enemy lines, all the while collecting real-time battlefield tactical intelligence that commanders could exploit in real-time, while being located safely behind friendly lines?
During this same period of time the USAF was looking to develop an aircraft that could take advantage of recent air to ground radar technology revelations. The concept behind such emerging capabilities was to use a large phased array radar, mounted on an airplane, to provide real-time Ground Moving Target Indicator (GMTI) intelligence. GMTI is a radar mode that basically sees the movement of vehicles across large land masses, as well an associated Synthetic Aperture Radar (SAR) mode that could theoretically map the battlefield using high-resolution radar beams and computer processing instead of optical photography. Both modes are able to peer through inclement weather with ease, can be implemented at long-range, and are persistent in nature. In other words, they can be used to survey enemy territory for long periods of time, looking for not just targets but operational trends in the enemy’s force posture, under almost any conditions. This new radar technology development program was known as “Pave Mover,” and it would prove to have drastic effects on the future of airborne intelligence collection.
With the “Pave Mover” radar concept and Northrop’s stealthy and persistent tactical intelligence aircraft in mind, the folks at DARPA decided to combine the two into a top-secret program now known officially as the Battlefield Surveillance Aircraft-Experimental (BSAX), code name “Tacit Blue.” By combining the deep penetrating radar capabilities of “Pave Mover” and Northrop’s stealthy surveillance platform, commanders would theoretically be able to look deeper into enemy territory than ever previously imagined, and the products of such a capability could truly be war winning. The only problem would be, how would Northrop engineers leverage a new design philosophy that was still in its infancy to be able to carry a massive radar array while staying invisible to radar at the same time? Further, how would they ensure that the radar itself was not detected through its high power emissions? The program’s goals were truly groundbreaking and in being so they were also incredibly challenging. Literally, the BSAX had to not just blaze a single trail, but many in order to be successful.
Around the turn of the decade, Northrop had designed an aircraft that was so ugly that it had to be genius, and it was. Resembling a whale, including its blow-hole on top (the jet air intake!) the Tacit Blue was a marvel of function over form. Instead of using the faceted, almost diamond like approach to designing their stealth aircraft, as Lockheed had done a couple of years prior, Northrop engineers took a different approach, one of continuous curvatures, chined edges, and masked vulnerabilities. Much of this design philosophy was demanded by the “loiter” part of Tacit Blue’s mission requirements. The aircraft had to feature “all aspect stealth,” whereas an aircraft like the F-117 could be optimized for front and rear, or “coming and going” stealth aspects, as their mission was sneak inside a defense network, drop bombs, and high tail it out of danger. Tacit Blue had no such luxury as it would have to loiter for hours over enemy territory, and thus every angle would be susceptible to radar surveillance for prolonged periods of time. Tacit Blue’s rounded approach to stealth, known as curvilinear design, would be a massive development that would affect future stealth technology arguably more than the famous F-117′s “faceted” approach to masking radar signatures.
The Tacit Blue Weighed in at some 30,000lbs, measured around 55′X55′ and looking more like a motor-home than an aircraft. With a massive phased array radar, provided by Hughes, shoehorned into its boxcar fuselage, the ugly Whale was one unaerodynamic flying creature. It’s surfaces were so smooth that it almost took on a sculpted appearance. This does make some sense as one of its main designers actually sculpted its unique fascia while sitting on a park bench after being stumped on how to come up with a solution for DARPA’s BSAX challenge. By its very nature, Tacit Blue was a highly unstable design and thus had to utilize an advanced fly-wire-system similar to the one used on YF-16. Making the aircraft even more awkward, the design team utilized many parts from existing aircraft to minimize design time, complexity and cost. At a price tag of about $130,000,000 to build, with a total program cost of about $170,000,000, the Whale was an expensive ugly duckling, but it would pay for itself in spades over some 135 test flights between 1983 and 1985.
During these 135 test flights Tacit Blue and the whole BSAX team would not only pave the way for a multitude of stealth and surveillance technologies, but in doing so it would make the exact case for a TIER3- unmanned stealth and persistent tactical reconnaissance requirement that would spawn the RQ-3 Darkstar some ten years later, and eventually the RQ-170 another decade after that. In many ways Tacit Blue was the manned experimental RQ-170 of decades past. Here are some of the key BSAX program’s accomplishments:
1.) “Curvilinear” and “All-Aspect” Stealth- Tacit Blue’s design was incredibly unique for its time, and many, if not all of its features can be seen today on modern stealth aircraft and UAVs. Its continuously curving architecture was revolutionary and would pave the way and help validate the design for Northrop’s B-2A Bomber, still America’s most valuable (that we know of) deep penetrating weapon system some 20+ years after it’s unveiling. Also, the “Whale’s” exact design was almost exactly copied for the Tri-Service Standoff Attack Missile (TSSAM), although the program was cancelled in 1993 due to budget and technological reasons, similarities are still abundant on the JASSM missile system currently in service. Its chined forward fuselage bears a close family resemblance to that seen on the YF-23, and it’s elliptical exhaust can be identified on the RQ-170 Sentinel. It’s overhead stealthy jet inlet, and deep buried motors are both concepts utilized to a great degree on the B-2 and RQ-170 as well.
Tacit Blue’s “all aspect” stealth design philosophy has been used in almost every low observable product in existence today and can be seen extrapolated to a greater, more refined degree on the f-22 and F-35. In fact the “curvilinear” design method, aided by much more powerful computer aided design software and processors, would allow stealth aircraft to be configured more freely for many different kinds of missions and uses as compared to the F-117′s inefficient and limiting faceted architecture. Although the Tacit Blue’s design was so ahead of its time it seems as if it is still being used today with minimal modifications. Case in point is General Atomics’s new Predator C, also known as the Avenger, which possesses and uncanny resemblance to Tacit Blue some 25 years after its last flight. In summary, structurally alone, the Tacit Blue changed the way America builds aerial weaponry forever, arguably more so than the more popular “Have Blue” demonstrator and it’s infamous F-117 successor.
2.) Infra Red Heat, Noise, and Optical Signature Reduction- It is said that the Tacit Blue was literally the coolest aircraft ever tested at the time. The aircraft ejected its exhaust before and above the end of aircraft’s tail section. This made the motor’s direct heat signature masked to anyone viewing the aircraft from below. It is also said that Tacit Blue’s exhaust was “after cooled” or chilled after being ejected from the aircraft’s engine, and this, combined with chemicals injected into the exhaust, all but eliminated the possibility of creating a contrail or being detected with infra-red sensors. Further, its light paint was optimized for medium and high altitude operations during daytime, and its deeply buried motors made the aircraft incredibly quiet. All of this and of course the unlikely overall shape of the Tacit Blue would make the aircraft almost entirely undetectable. These low-signature revelations would be exploited in advanced military aircraft design for decades after the Whale’s last flight.
3.) Low Probability Of Intercept (LPI) Radar- The Tacit Blue’s design was extremely stealthy, but packing a huge radar that emits tremendous amounts of energy over or near an enemy battlefield is not stealthy to say the least. Passive detection devices and Electronic Support Measures (ESM) could alert the enemy to the BSAX’s whereabouts almost as easily as radar detection if it’s radar were to be employed in a normal fashion. So engineers from Hughes and Northrop worked on cutting-edge ideas to make what was already a breakthrough radar technology, that being Ground Moving Target Indicator (GMTI) capability, all that more revolutionary by making its electronic emissions almost impossible to detect by the enemy.
LPI radar works using a variety of tactics that combine collectively to lower the possibility of a radar being detected while turned on. Advanced methods such as utilizing agile frequency modulation over a very wide band, emitting a much more finely tuned beam at lower power for short bursts instead of long continuous emissions, all via a phased array radar design that is paired with advanced back-end computing power fantastically lowered the chances of the Tacit Blue being detected via its emissions. Today LPI radar techniques, especially when joined with new Active Electronically Scanned Array (AESA) radar sets has changed the way radar is used in aerial and sea combat. The technology was most certainly used in the ATB program which produced the B-2A Spirit that was fielded just a few years after the Whale made its last flight. At the time the B-2 was a fantastic asset to migrate LPI airborne radar technology into because it had massive real estate on it’s leading edge for a pair phased array radar arrays to be installed, and it could utilize them while under it’s stealth cloak. Today, stealth fighters like the F-22 and F-35, and even modern combat ships use advanced LPI radars to their advantage, allowing them to keep tabs and engage their enemies while maintaining a high degree of invisibility. Further, the exact LPI and GMTI technology pioneered by Tacit Blue, improved and miniaturized over time, most likely makes it possible for the stealthy RQ-170 Sentinel to penetrate deep into enemy territory and actively gather high-resolution radar intelligence without being detected. This has been further confirmed by Pentagon officials in a recent piece posted over at Aviation Week where sources said that the RQ-170 started out as a radar platform and then was refitted for electre-optical streaming video as well a few years back.
4.) Data Links: Unlike Tacit Blue’s larger, standoff oriented successor, the Boeing 707 based E-8 J-STARS, which emerged as the chosen production platform as a result of the multi-tiered “Pave Mover” demonstration program, Tacit Blue had no radar and intelligence support operators on-board. Seeing how the requirement for real-time intelligence was a key part of the “Pave Mover” program and thus the BSAX program, engineers had to figure out a way to not only control the radar but also broadcast the stealthy Tacit Blue’s intelligence data back to operators on the ground for immediate exploitation. This was a massive departure from airborne intelligence collection of the day, which either saw large airframes utilized so that operators on-board could control the surveillance systems and utilize the information collected, or smaller airframes would be utilized to go out and collect intelligence that could only be leveraged once deciphered by specialists well after the mission ended. The incredibly high-risk nature of a deep penetrating, loitering, airborne surveillance platform’s mission set could be somewhat offset by relocating the radar operators and intelligence professionals off the aircraft and far behind friendly lines. These operators would be connected to the small stealthy airframe via a data link. Without breakthroughs data link technology Tacit Blue’s objectives would have been virtually impossible to achieve.
Tacit Blue used line of sight data links that were also low probability of intercept in nature and thus difficult to detect by the enemy. All the data collected over “enemy” territory was transferred back to the control station it was “tethered to,” theoretically far away from the front lines of the battlefield. At the time data links were used mainly between air superiority fighters to sort targets and to provide other situational awareness functions that would help crews be less reliant on radio communications, or in TV guided weaponry like the “Popeye” series of missiles.Tacit Blue stepped way beyond this capability and truly blazed the way for modern UAV technology and their related ground control and information exploitation concepts as we know them today. Most notably those used to satisfy the TIER2+ (which became the RQ-4 Global Hawk) and TIER3- (which became the RQ-3 Darkstar) requirements put forth by the USAF almost a decade after the Tacit Blue took its last flight. Today, data links, and LPI optimized data links, are used in almost every combat aircraft flying in the US’s inventory. These links primarily exist in the form of the Multifunctional Information Distribution System (MIDS)/Link-16 architecture. Further, a new data link optimized for stealth aircraft, which utilizes cutting edge LPI technology, is currently under development. This system is known as Multifunctional Advanced Data Link (MADL) which will be fielded on America’s stealth F-22, B-2, F-35 and Next Generation Bomber force. Modern data links have been described as the most game changing weapon system of the 21st century, and offer a single pilot a gods eye view of battlefield around him, with massive amounts of data being fused into a single tactical picture right at his or her fingertips. Never before has such a widespread capability existed, and it is arguably the most significant “force multiplier” concept combat aircraft have seen for decades.
5.) Ground Moving Target Indicators (GMTI) Radar Technology: As the deeply classified arm of the “Pave Mover” program, the Whale proved that such technology could be shoehorned into a relatively small tactical asset, when paired with a tethered ground station, and this aircraft could also be invisible to radar, loiter for hours in denied air space, peering deeper into enemy territory than a standoff asset could, literally into a foe’s vulnerable rear echelons. The testing done with Tacit Blue no doubt added greatly to the E-8 J-STARS program, and was further leveraged in the RQ-4 Global Hawk over a decade later, of which GMTI capability was one of the main capability requirements. It is also widely speculated that the RQ-170′s original mission was to provide high resolution Synthetic Aperture Radar (SAR) pictures and possibly GMTI data back to commanders on the ground to be used in real time. GMTI is not only effective at tracking armored columns, but it is also effective at cataloging critical “pattern of life” intelligence data in and around a target area. Since Tacit Blue flew with it’s mini-van sized Sideways Looking Aerial Radar (SLAR), such radar technology has been miniaturized to a massive degree. These radars can now be packed inside the dimensions of a targeting pod, while offering much more capability, and have become ideal for UAV operations.
6.) Dual-Role, Stealthy Electronic Intelligence (ELINT) Concept: Although the Tacit Blue may never have flown with passive ELINT hardware on-board, those involved with the program have made it clear that they were very aware of the “Whale’s” unique potential for carrying automated electronic listening equipment to passively collect the enemy’s electronic order of battle and their communications without them ever knowing. This ELINT suite of equipment could be manipulated and it’s products exploited in real-time by the ground control station just like the radar array. This information could then be used to great effect for Suppression of Enemy Air Defenses (SEAD) and general intelligence purposes. In other words, Tacit Blue could provide similar functions as the much larger, standoff in nature RC-135 “Rivet Joint,” as a secondary mission while conducting radar surveillance. Since the aircraft was already being theoretically risked over enemy territory it was only logical that such a risk be leveraged to its maximum potential in order to gain the maximum amount of rewards. This “cherry on top” added capability is very similar to what we know about the F-22 and it’s ALR-94 ESM kit, which some say is the most potent part of the Raptor weapon system, and supports what many hypothesize about the RQ-170, that it has a secondary ELINT capability built-in.
7.) Advanced Fly-By-Wire: The malformed Tacit Blue was unstable in both pitch and yaw and depended on a quadruple redundant fly-by-wire system in order to literally keep its nose pointed in the right direction. The aircraft was proven to flip on its back and weather-vein tail first into the airstream during wind tunnel tests! It has been said that the Whale was the most unstable aircraft mankind had ever flown at the time, a situation fraught with danger and pitfalls. Yet engineers were able to refine the flight control system enough so that the aircraft would fly reliably, although it was in no way a hot rod or high-performance machine. Lessons learned during the design and implementation of the “Whale’s” flight control system would be used later on as aircraft designs became more function over form. Thus opening up the opportunity to fly aircraft of strange, inherently unstable shapes, such as the B-2 flying wing bomber, and later the RQ-170 Sentinel. In the end, and against great odds, Northrop built an invisible sensor truck, and a flyable one at that.
As you read through the incredible accomplishments of the Tacit Blue / Whale / BSAX or whatever you want to call it, there can be little doubt that this aircraft was the progenitor of the TIER3- program, and thus the RQ-170 Sentinel as we know it today. The BSAX program definitively marks the first time in aerospace history where such a concept was envisioned, tested and validated. Additionally, as part of the decision to fund the Tacit Blue program, the USAF had a strong interest in utilizing the technology for an unmanned aircraft, a concept that was really beginning to emerge as the possible future of air combat at the time. Tacit Blue’s mission, persistent tactical reconnaissance over enemy airspace, is a very risky one. By taking human risk out of the equation the concept could be more readily applied during a time of conflict and the USAF knew this, although the technology to make such a capability reality simply did not exist at the time.
Almost everything we know about the TIER3- program that emerged in the mid 1990′s and the subsequent RQ-170 Sentinel that sprang from its ashes can be traced directly to Tacit Blue. It’s curvilinear low observable design was utilized extensively on the B-2 and can be seen leveraged to even a greater degree on the RQ-170. The same can be said for the RQ-170′s overhead inlet, deep buried motor and light paint optimized for daytime operation. Even the exhaust of the RQ-170 matches that of the Whale’s to an uncanny degree. Then there is the Tacit Blue’s data link systems, cutting edge at the time, that now represents the genesis of all unmanned aerial vehicles control interfaces. In effect the offspring of the Tacit Blue’s ground control stations and data links would make the unmanned aircraft concept as we know it today actually feasible. By the 1990′s breakthroughs in computer automation and satellite communications would let unmanned aircraft dream become a reality.
Low probability Of intercept surveillance radar and advance data links would make it so the RQ-170 could penetrate deep into enemy airspace and operate for hours without a high risk of being detected by passive listening systems. Even the proposed secondary ELINT capability of the BSAX is almost certainly on-board the RQ-170. Beyond logical deduction there were multiple reports from sources in the Pentagon that the RQ-170 not only transmitted real-time video on the night of the Bin Laden raid but that it was also providing key ELINT information so that commanders could monitor the Pakistani’s response, or lack thereof, at critical times during the fragile operation. Even the concept of using an aircraft as a sensor platform only, and communicating its collected data back to a ground station in real-time for interpretation, was the forerunner of the RQ-170′s real-time tactical reconnaissance capabilities.
The definitive proof that establishes a direct ancestral link between Tacit Blue and the RQ-170 Sentinel can be found in the very reason why the BSAX was created in the first place, to prove that a small stealthy tactical intelligence platform could loiter for long periods of time over denied airspace undetected, all the while transmitting its high fidelity intelligence back to commanders on the ground in real-time. Does this sound familiar? Of course it does, as this is the exact same unique mission requirements as the unmanned TIER3- concept that emerged almost a decade after the Whale’s last flight. Further, the BSAX was really a minimally manned asset, the pilot providing the flight control only because remote systems were simply incapable of doing so at the time, and were not needed in order to prove the concept during controlled tests. So although the larger 707 based E-8 J-STARS become the known winner of the “Pave Mover” program, the idea of a stealthy and persistent tactical surveillance aircraft was proven by Tacit Blue with flying colors. Further, it was realized that by simply replacing Tacit Blue’s radar, or in addition to it adding advanced imaging equipment, you would have an asset that would be almost entirely undetectable and capable of collecting multiple forms of intelligence during its high risk missions.
It would take a decade for satellite data links and computer hardware to catch up with the BSAX in order to make the concept an unmanned reality. Even the TIER3- requirement of the early 1990′s stated the need to leverage miniaturized LPI radars as part of the program, along with fully passive electro-optical surveillance payloads. And from the TIER3- minus requirement, and the program’s resulting RQ-3 Darkstar, the RQ-170 Sentinel was born, as was detailed in my prior piece linked above. So the Sentinel’s direct lineage, its exact reason for existing, dates back some 30 years to the birth of the BSAX program and Tacit Blue.
In the end the RQ-170′s pedigree is a long one of secret successes and public failures, culminating in a drone so effective and so critical to national security that it was used on the most sensitive American mission since the Doolittle Raid on Japan at the beginning of WWII. The fantastically successful Tacit Blue demonstrator, the clear father of the troubled Darkstar, the grandfather of the history making Sentinel, and the uncle of so many other successful aircraft that used smaller parts of its innovative technologies to accomplish their own diverse missions, leaves a legacy that is truly stunning. Yet one question does emerge out of this epic family saga: After learning so much about the success of the Tacit Blue, did this aircraft and it’s mission set in fact go the way of the RQ-3 Darkstar, being evolved into a more operational form under a dark classified cloak? Even the Tacit blue took over a decade from its last flight to become partially declassified. What is to say that a follow-on, much more capable system was not fielded once the BSAX technology demonstration program shutdown? Just as the standoff oriented “TIER2+” RQ-4 Global Hawk was pursued in the white world and the “TIER3-” RQ-170 was pursued in the black, maybe the similarly standoff oriented E-8 J-STARS and a stealthy tactical Tacit Blue follow-on blazed a similar path? Isn’t this more probable than not when compared to historical patterns of evolution regarding such programs and game changing capabilities?
Was Tacit Blue’s first actual offspring the fabled manned TR-3A “Black Manta” that was spotted around the globe, supposedly assisted the F-117A over Baghdad, and possibly crashed at Royal Air Force Base Boscombe Down in the 1994, or an aircraft similar to it? Only a couple of months after this mysterious crash at Boscombe Down of an aircraft that fits the proposed tactical manned stealth reconnaissance aircraft mold, the SR-71 program was reactivated against huge odds. Regardless of any speculative details it just seems somewhat apparent there may in fact be a manned missing linkin the RQ-170′s murky family tree. Something existing between the Tacit Blue technology demonstrator and the TIER3- unmanned requirement of the mid 1990′s seems like almost a given considering the historic continuity of such programs. Or are we really to believe that the USAF, after the conclusion of the Tacit Blue program, with such an innovative and proven tactical battlefield intelligence technology in hand, decided not to pursue a follow-on in any form until the curious announcement of the TIER3- program that resulted in the still-birth of Darkstar in the mid 1990′s? Was there really no aircraft to fill this role, even in very small numbers, between the triumphant Tacit Blue’s last flight, and the far-reaching unmanned TIER3- program? Would the existence of such a craft in fact also provide an answer to the odd SR-71 Blackbird retirement initiative of the late 1980′s?
The SR-71 was designed during a time when true stealth was a pipe-dream and thus it had to leverage high altitudes, great speed, and some rudimentary low observable techniques to survive. It would make sense that once the proverbial stealth genie was out of the bottle there would be no need for hugely expensive ultra high-speed reconnaissance over enemy territory. In fact a theoretical aircraft like the TR-3A that utilized subsonic, and/or moderate super-cruise operating speeds while at medium altitudes, and offered near radar invisibility, could actually possess an advantage over one that utilized blistering high speeds and altitudes. Slower speeds would give the platform more time to soak up intelligence data while remaining undetected, and if need be, like the Tacit Blue, it could loiter for long periods of time over denied territory. Did this reasonably faster, more capable and survivable offspring of Tacit Blue nicely fill the gap, along with modern strategic satellite reconnaissance, left by the retirement of the SR-71 Blackbird? One that not only inhabited Tacit Blue’s unique mission set and exploited it’s groundbreaking innovations, but also one that incorporated some of the innovations applied to the B-2 bomber, and the technologies that were publicly showcased during the Advanced Tactical Fighter (ATF) program in the form of the YF-23, although a few years prior, while they were still under a dark shroud of secrecy? Was this in fact Northrop’s ASTRA (Advanced Stealth Reconnaissance Aircraft) that was rumored to exist during the time period in question? It sure makes a lot more sense than the almost mainstream obsession with the possible existence of the “Aurora” high-speed, high altitude spy plane, that would have been unbelievably expensive to develop and operate, while only furnishing similar capabilities than those of spy satellites that the DoD and US intelligence apparatus has already invested in heavily.
If you asked me my opinion on this a month ago I would have said it would be anyone’s guess, but after the hours of research on the RQ-170′s lineage, it would appear that there is indeed an aircraft flagrantly missing from its family tree. Some 10+ years would have gone by between the time that this invaluable capability was proven and when we would see a publicrequirement from the USAF to fill such a role in the guise of the unmanned TIER3- program. But was the TIER3- the first attempt at an operational stealth tactical reconnaissance capability, or was it set in place to replace an aircraft that already existed, its main weakness being that human beings were at risk in the cockpit?
I believe that the BSAX did in fact result in a semi-operational manned airframe of a different configuration, but one of the exact same mission, that leveraged both Tacit Blue, and it’s emerging B-2 cousin’s technology innovations. Such an aircraft would help more evenly fill the gap left by the aging and vulnerable SR-71s on a tactical level, leaving satellites for the strategic reconnaissance mission. Theorizing freely, possibly this program never reached its full potential and was abandoned after a fatal crash at RAF Boscombe Down in 1994, thus ushering in the Blackbird as a stopgap and the TIER3- as a final replacement.
Like so many things that prowl the skies high above the central Nevada desert, we may never truly know their whole story, although we can apply logic, patterns in aerospace development, known facts and liberal creativity to create a story that is more probable than possible, and probably more believable than the actual truth….
Predator C
RQ-180 under construction
