In the early 1980s, an aircraft emerged in the United States that completely changed how we view aviation technology – or should that be, how we can’t view it? That cryptic half-joke will become a little clearer shortly I promise.
When the F-117 Nighthawk appeared, with its revolutionary, batman-esque exterior, the world was introduced to stealth technology for the first time. An aircraft could now evade radar detection thanks to its unique design, yet while the F-117 was certainly the first public, real-world demonstration of the use of stealth during the U.S invasion of Panama at the end of 1989, it most certainly wasn’t the aircraft to do so.
That accolade goes to a little known experimental aircraft that first flew in 1977, and without it, the F-117 would almost certainly not have followed so quickly – this is the Lockheed Have Blue.
In the early days of the Cold War, the U.S felt quietly confident about their aircraft’s ability to enter enemy airspace without significant threat from the ground. But this began to change in the late 1960s and early 1970s as the Soviet defensive network leapt forward. Suddenly there was a very real danger of an aircraft being blasted out of the skies by a radar-guided surface to air missile (SAM) or by anti-aircraft artillery.
The Vietnam War was a painful example of this, with the U.S losing close to 10,000 aircraft, helicopters or unmanned aerial vehicles (UAVs). Nearly 17,000 Soviet technicians and operators were deployed across North Vietnam to either train or operate the SAMs themselves, while the Vietnamese were often sent to the Soviet Union to learn the trade of how to successfully blow a Yankee plane out of the sky.
The most famous of these SAMs was certainly the S-75, a high-altitude air defence system, complete with a surface-to-air missile and command guidance. This was the missile that shot down Gary Powers’ U.S spy plane in 1960 and went on to be a tremendous asset for the defence of North Vietnam.
And it wasn’t just the U.S that suffered horribly from this new breed of defence system. During the Yom Kippur War in 1973, the Israeli Air Force lost 109 aircraft in just 18 days as the Soviet Union showed their support for the Arab coalition.
With all of this information, war game scenarios tested out in the United States mimicking a possible NATO war with the Soviet Union and Warsaw Pact countries painted a bleak picture. If the Israeli loss ratio was anything to go by, the loss of aircraft and human life would be unacceptably high. In fact, it was estimated that NATO aircraft reserves would be depleted in just two weeks should a full-scale war erupt.
With most aircraft unable to fly high enough to evade a missile attack, there needed to be an alternative. And I think we can all agree that invisibility is a pretty good 2nd best. Now, obviously, I don’t mean the aircraft is physically invisible to the human eye, but what if you could design an aircraft in such a way that it wouldn’t show up on radar? Without a radar signal, you’re relying on human sight, a prospect far more appealing than a torrent of V-750 missiles hurtling towards you at around 3,704 km/h (2,310 mph.)
This was the mandate presented to the Defense Advanced Research Projects Agency (DARPA) in the early 1970s. In 1974, DARPA secretly requested feedback from five companies initially involved, Fairchild, Grumman, General Dynamics, McDonnell Douglas and Northrop regarding the feasibility of creating an aircraft with next to no radar signature.
To give you a good idea of just how mammoth this kind of endeavour was, Fairchild, Grumman and General Dynamics all declined to participate further at this point, while McDonnell Douglas and Northrop both received $100,000 to continue with their research – that’s around $550,000 today.
But of course, we are missing one very important company. Lockheed was not among the initial companies approached by DARPA. It had been out of the fighter aircraft game for almost a decade and had perhaps been overlooked because of it.
However, word of this groundbreaking research eventually reached the upper echelons of the Lockheed hierarchy and they were permitted by the CIA to discuss the projects with DARPA. Initially, they were refused participation because of funding limitations, but eventually, Lockheed was welcomed on board, albeit without a governmental contract like McDonnell Douglas and Northrop.
At Lockheed, this project fell to the quasi-mysterious experimental division known as Skunk Works – and if that description pricked your interest, we’ve already done an entire video on this legendary team, so it’s well worth a watch after this.
As the Skunk Works team began to examine their monumental challenge, a few ideas emerged. Denys Overholser first suggested an aircraft with all flat surfaces, which you would then tilt over and away from the radar view angle. A mathematician, Bill Schroeder was also hired, along with Kenneth Watson as the senior lead aircraft designer, and over the next month, the team created a computer program called Echo 1 that could test different radar cross-sections (RCS) designs. But it soon became clear that the program itself wasn’t quite right, which was throwing off all of its calculations.
The Man From Moscow
And would you have it, the Soviets came to the rescue. Well, not exactly, but without the input of one Soviet physicist and mathematician, Pyotr Yakovlevich Ufimtsev, things may have taken considerably longer.
When Ufimtsev published his paper titled Method of Edge Waves in the Physical Theory of Diffraction in 1962 he was allowed to release it to the international community because – and you’ll like this – it was of ‘no significant military or economic value’. I mean really, who cared how radar reflected at that point. Ufimtsev had developed a high-frequency asymptotic theory for predicting the scattering of electromagnetic waves from two-dimensional and three-dimensional objects and funnily enough, just as the team at Skunk Works were beginning to struggle, they came across his paper.
It was precisely what they needed and helped them to refine the Echo 1 software and quickly choose from the 20 models they had been toying with. Ufimtsev has gone on to enjoy a stellar career and is sometimes referred to as the father of stealth, with Soviet bosses no doubt left a little miffed that they missed that one.
The Hopeless Diamond
The design that Echo 1 chose as the most desirable was odd and it’s fair to say that not everybody was convinced, including Kelly Jonhson, President of Lockheed at the time. The design was essentially all about triangles when viewed from different angles. A 90-degree angle gives off a clear radar reflection so the design needed to use oblique and obtuse angles only.
This led to a shape that reminded people of the Hope Diamond, one of the most famous jewels in the world that also appears to be constructed with a series of triangles. But as I said, not everybody was convinced, and the design quickly earned the unfortunate nickname, the Hopeless Diamond.
A series of wooden mockups were built that quickly highlighted some of the challenges involved with creating such a revolutionary design, not least the problem of how to make all the flat surfaces come to a single point in one corner – a problem that would rear its head again when the aircraft was built for real. However, on the plus side, Echo 1’s calculations were found to be spot on, and the wooden mock-up of what would go on to become the Have Blue was indeed found to give off almost no radar signature.
But remember that there were still two other companies in this race – though not for long. When all three were invited to build a test aircraft under the “Experimental Survivable Testbed” (XST), McDonnell Douglas immediately withdrew having failed to design a suitable aircraft.
That left just Lockheed and Northrup to battle it out during XST phase 1, which involved constructing a full-scale mock-up and carrying out wind tunnel tests. Only then would a single company be invited to continue into Phase 2, with each receiving $1.5 million ($7.5 million today) in November 1975 for Phase 1. In April 1976, Lockheed was declared the winner, though DARPA had been hugely impressed with Northrup’s work and the foundation they had set went on to serve them well with the Tactic Blue and B2 Bomber, both stealth aircraft, eventually produced by the company.
With the competition now out of the way, Skunk Works instigated Phase 2 which required several things; ‘reduced visibility in the radio wave, infrared, and visual spectrums and reduced acoustical observability and acceptable flying qualities. Surely they would have prefered great flying qualities, but it was clear that reduced radar visibility took precedence over flying manoeuvrability, at least in the early stages.
Lockheed produced two Have Blue demonstrators, HB1001 and HB 1002, with the first ready for testing in October 1977, after production had been held up by a machinist strike within Lockheed’s factory. The story goes that Lockheed managers themselves rolled up their sleeves and did the hard work themselves to make the deadline.
The Have Blue demonstrators were a mishmash of parts from different aircraft. They used the landing gear from a Northrop F-5 fighter, the flight control system was borrowed from the F-16 and the engines, two General Electric J85-GE-4As, were the same as on the T-2C Buckeye. The inlets of these engines were covered by a low-RCS grid and during takeoff, blow-in doors on the upper fuselage sucked in the higher amounts of air needed, while retaining its stealth cover.
Now, when you look at the Have Blue you probably immediately think of the F-117. They both shared the same swept-wing design and of course, both had similar exterior designs. The Have Blue was however much smaller, and its 4,173–5,669 kg (9,200–12,500 lb) weight was about a quarter of that of the F-117.
It had a length of 14.40 metres (47 ft 3 in) and a wingspan of 6.86 m (22 ft 6 in) – both much less than the F-117 – and a maximum speed of 965 km/h (600 mph). However, we should add that this wasn’t a particularly stable aircraft, the focus was almost entirely on the stealth technology and the chaotic ride it delivered led to it being christened with another nickname, the Wobbly Goblin. With such extreme instability, the onboard computer would need to make constant calculations to simply keep the aircraft in the air. As I said, almost invisible, terrible at flying.
A radar-absorbent material (RAM), which was mainly an iron paint created by Lockheed, was applied to every surface, while the windscreen had a special coating added to give it a metallic look, which would also help to reflect radar signals.
The first-ever stealth aircraft, HB1001, took to the skies for its maiden flight on 1st December 1977. And I think it’s fair to say, with more than a few doubts surrounding this revolutionary piece of technology. Lockheed had certainly put together an aircraft that had an incredibly small radar signature, but could it actually fly? Memos sent around this time make it clear just how erratic HB 1001 was in the air, saying that the aircraft experienced just about every mode of unstable behaviour possible for an aircraft – which is probably not what test pilot Bill Park wanted to hear as he climbed into the cockpit for its first flight.
But actually, things seemed to go quite well – for a while at least. During early testing, HB1001 was always chased by a T-38, with the two pilots switching roles, while those on the ground monitored the Have Blue’s capabilities.
Remarkably for such an unstable brute, HB 1001 successfully got through 35 test flights completely unscathed. However, on the 36th flight, on 4th May 1978, while coming in to land, the aircraft suddenly pitched down and made contact with the ground. The pilot was able to abort the landing and gain altitude, but it soon became clear that the landing gear had been damaged and that a normal landing would now be impossible. HB 1001 was flown until its fuel ran out, at which point the pilot bailed out and the first aircraft to successfully evade radar detection exploded as it hit the ground.
Luckily for everybody involved, HB 1002 was almost ready when the first aircraft met its fiery demise and first took off on 20th July 1978. Engineers had already learnt a lot from HB 1001 and the second incarnation did even better than the first, managing 51 successful flights, before experiencing a hydraulic leak that led to an engine fire. The pilot managed to eject safely and once again, a Have Blue aircraft became an angry ball of fire.
Now, I know what you’re thinking at this point. These tests don’t exactly sound positive, what with just 86 test flights and both aircraft completely destroyed – but this was far from a failure. Remember that these were demonstrator aircraft, meaning that they were essentially test vehicles for a technology that would most likely be adapted for another aircraft if proven successful. The two tiny Have Blue planes were never designed to be the finished article, instead, they were simply the rawest example of stealth technology. And despite both ending life in a huge explosion and then being buried somewhat mysteriously on the Nellis Air Force Base Complex, they had proven their worth.
The Road to the F-117
Even before testing had been completed, the U.S Airforce wanted more. In October 1977, Lockheed was awarded another contract, under the codename Senior Trend for a fully operational aircraft with the same stealth technology. It would be another four years until the F-117 Nighthawk finally emerged, larger, more stable and vastly better equipped than the shaky Have Blue aircraft, but unquestionably the same family tree.
Demonstrator aircraft rarely get the attention they deserve and this is certainly the case here. While the Nighthawk quickly achieved legendary status around the world, the name Have Blue has faded. However, in terms of stealth technology, these two bucking bronco aircraft, which cost $35 million ($156 million today), were where it all began.