Why was the F-117 retired so quickly?
technology.org
technology.org
In 1999 over Serbia, one F-117 was shot down and supposedly another one was damaged. It was shot down by a Russian S-125, which is a missile system from the early sixties.
The Serb air defense officer that shot it down says that the F-117 was detected by his radar at 23km. He developed the tactic of moving his radar and missile launcher regularly, and then only turning on the radar for a short time and moving again. He says that the F-117s going into Serbia were following the same flight path over and over and he figured out a good time and place to turn on the radar.
In the book Skunk Works, there's some detail about the mission planning that goes on for F-117 missions. They have software that, given the positions and types of radars, will find the lowest risk path in to the target. This is also referenced here: [1]
Knowing all of this, you can surmise that the F-117 is detectible out to 20-30km (depending on angle), but they simply route the planes to go around the radars. Presumably if a new radar pops up, the F-117 can detect this (or be cued by an AWACS or EW plane) and fly another way, or turn around. However, if the radar pops up suddenly, it may be too late.
Once the effectiveness of this tactic was proven, the value of the F-117 went down a lot. Then you start looking at the other deficiencies of the plane. It has a small bomb load, not very long range, no supersonic capability, limited sensors, no air to air capability. If the plane is invincible, these are forgivable, but if not, then maybe not.
Anyhow despite all of that, they still fly the F-117 in retirement for training and testing purposes, and they still get sighted in the air and on ramps periodically.
[0] https://upload.wikimedia.org/wikipedia/commons/c/c0/Serbian_...
Croatian - your plane is burning Serbian - Mine is visible but doesn't fall Aircraft waste budanivci Bosnian - WE ALSO HAVE PARTS FROM F - 117A Serbian - Suddenly the earth got in his way Bosnian - Missed the airport in Surčin Ukranian - Dad, types without a hand Serbian - WHAT WILL HAPPEN TO THE WHITE HOUSE? I'M GOING TO LIGHT IT UP Serbian - Last post office budjanovci Serbian - Give me another one....we need to cover the pigsty Serbian - What does a child know what is invisible Croatian - We will fuck NATO, my brother! Serbian - briefly but fucking
Is that accurate?
I thought the F-117 was still more stealthy than 4th & 5th jets.
https://photo2.tinhte.vn/data/attachment-files/2022/09/61180...
Are you really know, how expensive jet service? What you know about top secret military jet service costs?
Or may be you think, you could just drop F-117 on parking even without guard? Sure, why guard them, when they should guard themselves? ;)
The real reason to retire the F-117 was because the B-2 could stealthily deliver more bombs anyways and they wanted to free up funding for other projects, not because the F-117 couldn't dog fight. That wasn't its job.
BTW, Lockheed offered to create larger variant, but Boeing project chosen.
It proved that super low radar signatures were possible.
The design used those big low poly triangles not because it’s optimal (aerodynamically, very much not!) but because of the limits of computer simulation at the time.
There’s a whole fascinating story about how the theory behind low observable was developed by a Soviet scientist, published, ignored there, then implemented here.
But computer technology quickly advanced to where low-poly aircraft made airworthy by brute force were no longer necessary. See the B2 Spirit, also a very special simulation derived shape but streamlined.
Is this true? I thought the low poly was that a curve always has an area whose norma vector points back to radar, where flat pieces (and their intersections) only do if they're perpendicular to the radar. So, unless you're unlucky enough to have one plate shining pointing back at the radar, the reflection is completely broken up, with the small corners being too small to effectively reflect radar wavelengths back.
Or, maybe I'm just having trouble visualizing a smooth surface geometry that also has few normals back? I naively assumed the "smooth" planes were enabled by better absorption materials, rather than geometry. Maybe a mix?
You're not wrong. From a head-on perspective, especially from below, you'll find few if any curves. Newer stealth planes look curvier because photographs are often taken from above where the canopy is prominent, and where the top of the body and wings have some curvature. But look more closely. Even from above, the curves you see are usually on the trailing portion of surfaces or facing laterally; the leading edge of the wings on a B-2, F-22, or F-35 are actually flat and triangular, not at all like a typical diagram of an airfoil. This is especially true of the F-22 and F-35--if you look very closely, they're far more angular from more perspectives than the older B-2. The B-2 looks curvier from below, but the flying wing design isn't a coincidence; and I believe the B-2 also relies more heavily on radar absorbing skin than later aircraft, which rely more on simple geometry much like the F-117.
Moreover, beneath the skin of these planes it's widely believed that the framing uses sawtooth and other similar polygonal patterns you'd expect, a mitigation for radar that passes through the skin. And I would think that part of the engineering of these aircraft leverages radar transparent skin in some areas, not just absorbant skin, similar to a nose cone holding a radar.
Here's a really amazing slide presentation on the basics of stealth design: https://understandingairplanes.com/Stealth-Airplane-Design.p... (I first came across that document via an HN post several years ago.)
- Lockheed Stealth by Bill Sweetman
- America's Stealth Fighers and Bombers by James C. Goodall
- Stealth Technology by J. Jones
- Stealth Warplanes by Dough Richardson
- The Radar Game: Understanding Stealth and Aircraft Survivability by Rebecca Grant
- Skunk Works by Ben R. Rich
And by Bill Sweetman
- Inside the Stealth Bomber
- Joint Strike Figher
- F-22 Raptor
There is also a good playlist on youtube covering some of the topics:
https://www.youtube.com/playlist?list=PLfIy3BUXB3vLu1ZZz9bQb...
Anyway, the basic principle of stealth design is not what people intuitively think. As I recall, it has more to do with refraction along edges than reflection from surfaces. It was originally figured out by some Russian guy. I think that story was also in the book I can't remember.
> maybe I'm just having trouble visualizing a smooth surface geometry that also has few normals back?
https://en.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit
https://en.wikipedia.org/wiki/Northrop_Grumman_B-21_Raider
The interface where the top and bottom meet (ie the only surfaces normal to the horizon, since they intentionally deleted vertical control surfaces) have relatively sharp edges and curvatures.
Curves are okay, as long as you plan them correctly. The tighter the curve the smaller the radar return. After all, the F-117's corners are (in the limit) just curves with a very tight radius.
The other trick is that (when viewed from the top) all the lines along the perimeter are parallel. That means there are only ~4 azimuth angles where the edges are presented 'face on' to an observer. At all other azimuth angles the radar return will glance off the (importantly, singly-curved) outer edge, bouncing the return signal away from the radar.
Presumably they'll plan flight paths such that these four relatively high-observability vectors will "sweep past" known radar installations rapidly, ideally while the plane is making a turn. All the radar sees is a small, extremely brief blip, which could well be discarded as a bogus radar return (either automatically or by human operators).
No insider information of course, just looking at the shape and applying geometric reasoning.
Furthermore, I have seen pictures of F22 with brown rust stains on panels that should not have any steel in them.
https://www.thedrive.com/the-war-zone/4729/the-toxic-death-p...
There would be always a question why did they chose a flying iron design, but efficency clearly states it's not needed.
It was so bad, they called it The Hopeless Diamond. To keep it in the air instead of dropping like a stone, flight computers had to be developed. Another stepping stone for the B2 which faced similar challenges.
Does anyone know?
At first I thought that was incredibly wasteful, then I realized it was actually brilliant, given the circumstances in which the plane was used.
The pilot told the Crew Chief via intercom "Engage Buicks". The Buick operator pressed "Jet Start", and movement of the Buick throttle (one throttle lever controls both engines) downward engaged the transmissions. . . . The pilot would watch his onboard gauges to confirm minimum oil pressure, fuel pressure, and rising RPM, and then set the jet throttle to idle. At that point 30cc of TEB was injected into the burner cans, a characteristic green flame was emitted, the J58 lit off, accelerated and started to run on its own. The accelerating jet started to unload the Buicks, and when 3,200 rpm was reached, the pilot called "Buicks out", the Crew Chief signaled "cut", the Buick operator hit "Cart Shutdown", the probe fell free passively, and the cart throttle automatically returned to idle.
https://www.thesr71blackbird.com/Aircraft/Engines/starting-t...
So the gist of the idea is not that far fetched.
(Now I'm wondering how the huge Diesel engines on massive boats are being started, I wouldn't be surprised if they were started by a smaller IC engine)
But then again, maybe while designing you observe that there's going to be a problem. You do realize that, say, the very different temperatures will inevitably produce too big an expansion for the connecting pipes to be leak-proof while flying, or maybe the expansion will be so big that the material will break when the engine reaches some temperature. So you try to design a solution to that problem. Maybe it would require a new material, which means almost inevitably years of research and a lot of money. Maybe you could design some very specialised connection that can operate at different temperatures and modify its geometry so that it doesn't leak at any temperature; which again may take a lot of time and money in research.
So, here comes the brilliance of the solution: You turn the design around. You define the connections' "normal state" to be the one at high temperature. You design for that, make sure that while in operation, there's no leak, the connections don't overpressure, the fit is right.
But obviously then what will happen is at low temperature the contraction of the material will produce leaks. But you think about it and realise that this only happens at landing/take-off, for the "brief" time that the plane is moving on the ground, which is both a much safer situation and a shorter amount of time. In those circumstances you can afford to have some leaks without it being so much of a problem.
So, it's not so much that the solution is "leaking fuel is brilliant", but that the design acknowledges the inevitability of a leak, and then moves the leak to the moment where its presence is less problematic. So you sacrifice some non-dangerous fuel loss on each mission, while allowing for a better, more secure solution on the moments the plane operates nominally. And all without needing those years/money spent on complex research.
1. There are no separate fuel tanks on the A-12/SR-71. The body of the aircraft is also the fuel tank. If there were internal fuel tanks separate from the body of the aircraft, then there wouldn't be any leaks. But then that would add weight and bulk that they couldn't afford.
2. The fuel they're burning is JP-7, which is so hard to ignite that it will put out a match, or if dumped on a fire, it will put out the fire. You have to get it to much higher temperatures for it to ignite. So, leaks that do happen at low temperatures (on the ground, early in the flight envelope, etc...) just aren't that big of a deal. There's not many things that would be able it ignite the fuel when it leaks at those times.
I’m totally speculating here.
I wasn't there but I have the impression that kerosene was not the limiting factor back then. So they solved an engineering problem (body expanding in multiple directions) by declaring, not a problem!
Because of this two books are interwoven in my brain, it’s a weird mashup.
> Some contemporary stealthy strategic bombers like the famous B-2 are able to remain unnoticed even in the presence of low-frequency radars. But new radar technologies threaten even these powerful stealth bombers. Therefore, the F-117, optimized to defeat high-frequency radars, is no longer relevant in current fights.
> Moreover, it cannot map out threat emitters in real time like its successors F-22 and F-35. It is also not able to survive when it is detected and confronted.
Ugh, that's not an easy/low-effort skill to pick up and run autonomously without effort.
Secondly the reason to care is that it's a waste of time. There are an infinite number of stories that sound vaguely interesting enough to click on. Previously there was a sort of filter of "and that someone actually investigated and decided it was indeed interesting enough to write about". That didn't happen here. The article tells you absolutely nothing beyond that it was retired, potentially because "new radar technologies threaten even these powerful stealth bombers. Therefore, the F-117, optimized to defeat high-frequency radars, is no longer relevant in current fights."
Is that even true? I don't know. There's a good chance it is, ChatGPT is right more often than it's wrong. But I'm pretty confident that there probably wasn't any human involved with the expertise necessary to fact check it.
And the bigger problem is that it isn't really interesting, at all. Maybe it could have been if it went into more detail into why and how exactly it stopped being effective at stealth because of modern radar. But it doesn't go into anything like that because it was written by a chatbot which was prompted by a human who only wanted some words they could publish, not any actually useful or interesting information.
Good topic, decent article, terrible way to answer the question in the title.
At the absolute bleeding edge of radar technology (like... probably decades and decades out) is developing and deploying quantum radar systems (these use entanglement to try to increase signal to noise).
https://en.wikipedia.org/wiki/Active_electronically_scanned_...
It's the tricks that are easier to deploy with AESA that achieve that - noise-like signal, higher receiver sensitivity allowing for lower emission power, clever signal processing etc.
I suppose it is just me, but really can't stand when a simple answer is drug out to a massive, article like this.
The comment about having to use low level attack craft to destroy specific radar types so the f117 can evade the other types is telling: "invisible to radar" was a bit hype-y
High frequency radars are more accurate than low frequency, nobody used low frequency at the time. They're also smaller, I don't think you could use a low frequency radar with a missile's seeker. Low frequency is good enough to throw up flak, though--and that's how the one that was lost got hit.
It was also vulnerable to bistatic radar--but I don't believe a bistatic radar could even have been built back then.
It was basically a one-trick wonder that got counterdesigned.
I don't think this is true. Low frequency was and continues to be the best option for early warning and over-the-horizon use cases.
> good enough to throw up flak, though - and that's how the one that was lost got hit
It was hit with a 1960s era SAM after running the same route again and again. https://en.m.wikipedia.org/wiki/1999_F-117A_shootdown
First, during the Cold War... the F-117 was one of America's silver bullets. Don't wanna risk anything getting leaked out.
In the 90s to early 2000's... who on earth would buy an F-117? Especially amongst nations friendly to the USA. With the exception of maybe Israel, no US aligned nation had a reason to have a low observable strike aircraft.
In the twilight of its career - well the JSF/F-35 existed. Why buy the old, single purpose, first generation stealth aircraft when F-35s should be just around the corner...
My understanding of this is that there's a threshold of "really good but not too good" that is a bit arbitrary. The F-117 and the follow-on F-22 Raptor both crossed over the line into "way too good" territory and couldn't be exported. While it's pretty cool having aircraft that are so advanced that no other country on earth can own them but your own, the net result ends up being... you don't have anyone to share the NRE costs with, which drives the unit cost and spare parts costs up like crazy.
Later he found that he was building sound baffles for incoming U2 flights; and the turbulence blew his work away after only a couple landings. Said it was good money and helped him get started. He was eventually one of the bigger military surplus dealers in the USA.
I figured it was landing turbulence; them things come in hot.
Most of what the public calls triangle UFOs is air-air-refueling practice
Desert Storm, sure.
12 years later for Iraqi Freedom? Nope. We were in the sandbox low key to kickstart Saddam's farewell/get-rekt party and back at Holloman much quicker than most other air expeditionary squadrons.
It was freaky.
https://www.thedrive.com/the-war-zone/f-117-nighthawks-caugh...
https://www.thedrive.com/the-war-zone/retired-f-117-nighthaw...
Really.
The real cockpit had at least two multifunction displays.
Modern digital avionics is the heart of this precision bombing platform, increasing mission effectiveness and decreasing pilot workload. The F-117 cockpit is equipped with Heads up display (HUD), twin color multifunction display indicators, and a digital moving map system.
https://www.f117sfa.org/about-the-f117
A cockpit picture: https://images.squarespace-cdn.com/content/v1/5a36dd6f8a02c7...
The larger display unit in the center was the primary human interface for IRADS video fed from FLIR/DLIR turrets.
https://www.military.com/military-life/how-air-force-pilot-b...
I think it is questionable ethically to "lead Ukraine on" in terms offering military support, if that support is intended to only be just enough to manage a bloody and protracted stalemate. We should either pressure them to settle, or genuinely offer enough weapons to help them succeed (pushing Russia to accept some kind of "'conditional' defeat 'with honor'"). Letting both countries bleed themselves out like its WW1 should not be an option.
However. There are many less nefarious reasons possible.
Sending more (capable) equipment costs money. It decreases your own readiness. It increases the possibility of proliferation. It risks the russians getting hold of it for analysis. It definitely has proven to irritate the Russians, risking escalation. More capable equipment requires more training and logistics that Ukraine does not have.
Note that for nations other than Russia and Ukraine, this conflict is strategic but not (yet) existential. We have not, and politically cannot, converted our economic output to the war effort. This lack of political and societal will explains why we're not fully comitted.