Lockheed F-117 Nighthawk – “Sir, orders are orders, but I'm not getting into it.”

In general, I was surprised that after searching, I found very little material about this aircraft on the Internet. On the one hand, this fact is explained by the fact that the aircraft has unprecedented fame, and almost no one needs to introduce it, but on the other hand, even among people with some experience in the field of aviation, I observe a surprising number of myths in the head about this F-underfavela.

So, we've all heard about this plane. F-117 Nighthawk, aka night hawk, aka STEALTH fighter, aka stealth, aka a pile of rubble in Yugoslavia. Many believe that this is “the greatest achievement of American scientists and engineers, and against its background the Soviet Union collapsed on its own from fear”, and many others believe the opposite: “this piece of metal from Star Wars barely lifts itself into the air. Look, they shot it down in Yugoslavia, how could they not, who needs your stealth then” – I have seen both of these points of view, and not only among our compatriots, but also among overseas representatives of the Internet. It is not for me to judge these people, it is not for me to judge the plane, but both points of view are profound misconceptions, which I now want to dispel, at least partially.

The history of this aircraft can be started from afar – from the moment in 1975, when the head of the secret division of the Lockheed company – “Skunkworks” – was replaced. The previous head of this department, Clarence “Kelly” Johnson is also an extremely respectable person in the history of world aviation, because under his name were created such aircraft as the U-2 (yes, the same one that was shot down near Sverdlovsk in 1960), the F-104 (yes, the one that did nothing but crash and generally attached the tail to the pipe), the SR-71 (yes, the one that is a whistle at 3 speeds of sound, leaking even before takeoff), the P-38 Lightning and many others. But now we are not talking about that, but about the fact that he was replaced by another person, Benjamin Rich, who will give the go-ahead for the development of our hero. By the way, as an interesting fact, Clarence Johnson himself, who worked as a chief consultant after leaving his post, spoke out sharply negatively towards this aircraft.

So, one fine day in the late 70s, Denis Overhauser, a mathematician and radar specialist working at Skunkworks, comes to Ben Rich with a short report. In it, he says that he read a book by Pyotr Ufimtsev (yes, Pyotr Ufimtsev was a Soviet scientist, but his books also made it to the West) called “The Method of Edge Waves in the Physical Theory of Diffraction,” and was able to derive formulas from there that would help calculate the so-called RCS – the aircraft’s effective scattering area – the main parameter for detecting an aircraft by radar. Overhauser also promised that he would be able to create a design for an aircraft with a record low RCS in a few months. Rich of course agreed, especially considering two factors: Lockheed itself was in a very difficult position at the time, because their major corruption scheme had been exposed (in short, Lockheed paid some countries to buy their planes), and there were major problems with their L-1011 airliner; and, on top of all this, DARPA (the US Defense Advanced Research Projects Agency) had secretly set up a project to develop a stealth aircraft because of the high losses of aircraft in Vietnam and elsewhere. The only catch in Overhauser's design was that ALL external parts of the plane had to be flat. This is explained rather prosaically by the fact that at that time (and let me remind you, it was 1975-6) there simply wasn’t enough computer power to calculate the already complex formulas, especially for non-flat figures, and therefore this measure served as nothing more than an optimization of the work, so that the calculations wouldn’t take more than a week for one part of the airframe.

So, after a couple of months of work, Overhauser presents his project. It was immediately dubbed the “Hopeless diamond” (the plane was given this name not only because of its shape, but also as a joke about the Hope Diamond). No one who saw this plane agreed that it would take off, and the head of the aerodynamics department even suggested burning Overhauser at the stake. However, the head of the department believed in the viability of the project, and managed to convince his team of this. And so the work began to boil. Soon a wooden model was built at a scale of about 1:5 relative to the plane itself. Having placed it next to the unmanned reconnaissance drone D-21, their RCS was tested in practice. And, to everyone's surprise, Overhauser's calculations turned out to be correct – the RCS of the model was about a thousand times smaller than that of the D-21. However, the magnificence of this freak did not end there. Ben Rich was able to negotiate with DARPA about participating in the competition, and when a full-size metal model 14 m long was presented for irradiation by a test radar in New Mexico (and the radar there was much more powerful than a regular airplane can afford), it turned out that under normal conditions it has an RCS like a golf ball, and in some conditions even like a roulette ball in a casino (a 14-meter model is visible on the radar as a 3-4 mm ball, as you can see). The Lockheed project was declared the absolute winner and two flying prototypes were ordered from the company.

Here's where things get interesting: it's one thing to build a mock-up, and quite another to build the same thing, only so that it can lift itself into the air, and preferably do it without all the groaning that's possible. The plane would inevitably lose in stealth – here you have the engines, both from the back and from the front, very faintly glowing on radars, and the cockpit, and the chassis, and the wing mechanization, and other materials for the structure, and so on and so forth. However, four months later (the mock-up won the DARPA competition in April 1976, and the project was ready by the end of July of the same year), a project was ready, which was a small plane with two engines and a mass of even less than five tons. Oddly enough, Have Blue turned out to be a relatively cheap plane (which, of course, cannot be said about the F-117), since it used existing units from already produced planes – the F-15, F-111, F-18, F-16 and even the B-52. Among other things, Have Blue inherited from them the EFB – the fly-by-wire control system. It played an extremely important role on board, because it is easy to guess that an airplane of such shape would not be able to support itself well in the air – technically speaking, the airplane was unstable in none of the three main axes. The EFB itself, without the need for the pilot to act, stabilized the airplane, which, according to the pilots, provided it with quite good stability in flight.

Despite the workers' strikes, both prototypes were ready within a year. Exactly at the request of the military, the prototypes began ground testing in the fall of 1977, and the first flight took place on December 1. The first few months of flights were carried out to eliminate childish mistakes and to fine-tune the aircraft. After that, the aircraft was sent to the most important stage of testing – checking the radio signature of all types and types of radars. In these tests, Have Blue really showed a record-breaking EPR and full compliance with the technical specifications. True, to great regret, both Have Blue aircraft were lost in accidents, with the second crashing on its penultimate flight. Despite this, the military recognized the program as an absolute success and ordered the construction of five pre-production copies of the future F-117.

There is an unspoken tradition in aviation – any first flight of a pre-production aircraft is made with a certain delay relative to the scheduled one. The Air Force wanted the first pre-production model to take off in the summer of 1980. But it turned out that… it didn't work out, and the YF-117A made its first flight only on June 18, 1981 (this designation is given to distinguish between serial F-117As and pre-production YF-117As). In fact, this delay was quite expected, because projects of this kind had never been in production before, and therefore there were more than enough technical problems. Despite this, the remaining 4 prototypes were produced on time, and their refinement was also not long in coming.

Even before the end of testing, the US Air Force had already signed a contract for 29 production aircraft, which was actually an extremely optimistic sentiment (or a well-constructed advertising campaign, who knows…), especially considering the skepticism of the Skunkworks workers. In total, 59 aircraft, including pre-production ones, were produced by 1990.

Less than one and a half thousand words have passed, and the conversation directly begins about the F-117 and its design features. Oddly enough, there is not such a long list of something unusual as one might expect, although there is something to talk about. The aircraft is made for complete absorption/reflection of radio waves in the wrong place, but these are not the only measures to hide it from enemy aircraft radars and ground detection stations. The entire aircraft is covered with a special anti-radar coating, developed in the same Skunkworks even before the start of work on the project. Another interesting feature of the aircraft and its stealth is the fact that its lower part is almost completely flat, which we will talk about in more detail a little later. In addition, the pilot's cockpit canopy is covered with a thin layer of metal in order to better hide it from the “eyes” of the enemy (if you explain it normally, then without this coating, glass is a radio-transparent material, and as a result, for an enemy radar in the nose of the aircraft there is a giant bathtub, which it can catch on to). Add to this the flat nozzles, cooling the exhaust gases from the engine by about two or three times (there was another killing feature – some of the air from the air intakes went through the cooling system directly into the nozzle, also cooling the exhaust gases), albeit with a decent loss of thrust, and as a result your plane is nothing more than a bird in the sky (for everyone except you and those you are approaching). By the way, about birds – despite the fact that the plane since the Have Blue received some hefty additional dimensions, weight, and various low-visibility-friendly elements, it was still comparable in visibility to a pigeon or a small raven, which is a very good indicator even for modern aircraft (for comparison, see the photo below, and about birds – a pigeon is 0.01 m2, a raven is 0.015-0.03 m2, as well as the F-117).

Now a few words about the use of the aircraft, after all, the EPR and design are good, but in practice it can be completely different. Anyone who has heard of this aircraft and has an idea of ​​aviation understands that it is not an airliner and not even a fighter. In fact (contrary to the opinion of a surprisingly large number of people), the F-117 is a tactical bomber that does not even engage in attack. It has a pair of internal bomb bays, which accommodate various guided bombs with a caliber of 500 to 2000 pounds, as well as small B61 atomic bombs (well, not small, up to 400 kt in TNT equivalent, after all). Also, for absolutely complete and endless invisibility, all flights on nighthawks were carried out only at night and, when approaching the target, in strict radio silence – even the radio altimeter and the friend-or-foe recognition and indication system were turned off. After that, many who can imagine this will lose the desire to fly them – about fifteen minutes after takeoff, and silence, and only after about twenty minutes can you start saying anything to the dispatcher again. And besides, during this entire time you can't see anything, and you only look at the instrument panel in search of targets. However, all these measures were not in vain – in the first ten years of flights, there were zero combat losses (by the way, non-combat losses were also very few, of which zero were fatal for the aircraft and/or pilots). The aircraft were actively used in the period from 1989 (the US invasion of Panama) to 2008 (although they are still flying, for example, in October last year, photos of them appeared over Area 51). Their finest hour is considered to be Desert Storm, where they actively bombed Iraq starting from the first night of combat operations. According to the Air Force, they proved highly effective there, and were used in all conflicts involving the US Air Force thereafter, up to Yugoslavia, where the fervor eventually died down.

And now about that very situation on March 27, 1999, 30-40 km from Belgrade.

But we are interested in the most important thing – how could a complex from the 1960s (let me remind you that the plane was shot down from a C-125 developed in 1961) see the most uber-mega-stealth of the 80s? And it's all very simple – remember how I talked about the flat bottom of the F-117? So, if there is a radar installation irradiating the plane from below, and a radar installation receiving a signal from the first (working on the principle – the angle of incidence is equal to the angle of reflection), then the plane will light up on them like the sun in outer space, which is what happened. Since then, all low-observable aircraft do not have large flat surfaces to avoid such cases. This is how they shot down an already not new, but still very cool in the minds of the population plane.

Many consider this incident as the greatest victory of some and an unreal crushing defeat of others. Although in reality (and this is very important to understand, including beyond the scope of this article) there is nothing surprising that an aircraft from the 80s, based on technologies from the 70s, was able to be shot down in 1999 and detected by systems from the second half of the 90s. Considering that in the entire service of the F-117 this is the only confirmed combat loss and the first combat loss in 10 years of active participation in military conflicts, it is hard to call the incident the collapse of the idea of ​​low visibility…

If we sum up this aircraft, then, in my opinion, it has shown itself extremely well, served well and even gave birth to a whole new direction in aviation – stealth. I like this aircraft – not only in terms of efficiency, but also in appearance – where else can you see such a chthonic, but at the same time serial and effective flying machine?

Author: Akim Inexplicable

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