16 ms·

Is it really possible to hide an aircraft from modern radar? Even if the aircraft had a radar footprint of a bird, no bird flies near or over mach 1.

joyjoyjoy 7y ago
No, it isnt. No aircraft can be stealthy by definition. You can see it, right? There are tons of detections methods, wavelengths and other stuff you can scan the sky with. And you may be able to evade some of them. In the end you buy low speed, low dog fighting capability, low payload and huge maintenance time for the bet that you may or may be not invisible. If your bet fails, it comes at a high costs since your one trick pony failed.
imtringued 7y ago
It is effective against missiles that are equipped with very small radars. Since new aircraft like the F-35 are equipped with strong ECM and no longer require dedicated jamming support aircraft you also cannot use the much wider radar of the aircraft to guide the missile. This means we are back to using infrared missiles which can be avoided by flares.
mysterydip 7y ago
Detection isn't the issue as much as determining what is clutter and what isn't. When you reduce your signal to the level of noise, you can go undetected a lot of the time.
Sharlin 7y ago
It is not about being confused with a bird, but simply about the fact that things that are less reflective (whether due to size, material, or geometry) are able to get closer before crossing the signal:noise threshold.
- b_tterc_p 7y ago
  How hard is it to generate noise?
  - taneq 7y ago
    Without being noticed? Noise where there should be none is a signal.
    - b_tterc_p 7y ago
      True, but if your enemy is expecting you to send a plane one random day in August, streaming constant noise on EVERY day in August is going to cost them resources and make it easier on the day that you pick.
raverbashing 7y ago
Primary radar is bad at determining speed, especially when the aircraft is not flying directly towards or away from it and even more difficult with a reduced radar signature. (ATC relies on secondary radar - that is, transponders)
atonse 7y ago
This is likely moot nowadays with drone technology, stealth drones, and modern cruise missiles. They're far more likely to be deployed to take out anti-air defenses before even these aircraft come in.
- monkeynotes 7y ago
  I often think about what use the modern fighter jet is. I'd be interested to know exactly what role they really play and why a F22 would be deployed risking a pilots life vs. a drone. Maybe the F22 has a bigger payload or more precision?
  - detritus 7y ago
    Situational awareness, jamming and reaction/ping times spring to mind immediately as being areas where having meat in the seat will remain advantageous for a while to come.
    - jacobush 7y ago
      I think situational awareness will remain very important to small to medium size air forces. I can't help but think of the Swedish Air Force. The idea was to be able to strike very hard if absolutely necessary. Otherwise, the air force would not be deployed at all. We never expected to operate in air superiority conditions. It was always about inflicting maximum damage to an invader. In such a situation you are already accepting heavy casualties and higher risk to the pilots seems more palatable if that means more room to improvise to achieve the objective.
- SEJeff 7y ago
  This is false. The US military still does SEAD missions with manned fighter bombers. We have no stealth drones capable of this yet. We also don't have hypersonic cruise missiles (yet), so modern cruise missiles aren't great against advanced air defense. A tomahawk flies a lot slower than an F22 as an example and isn't stealthy at all. Any near peer adversary, or one using near peer anti-air (so anything from Russia or China or imported from either) can knock out most of our cruise missiles provided we don't confuse it with ELINT / jamming. https://en.wikipedia.org/wiki/Suppression_of_Enemy_Air_Defenses https://en.wikipedia.org/wiki/Suppression_of_Enemy_Air_Defen...
natermer 7y ago
No. Not a F-22 or F-35 are unlikely to actually be invisible. A B-2 bomber has a better chance. The talking heads from the military may talk about 'invisibility', but they are full of shit. Just propaganda for the tax payer. The problem is the physical size of the jet. In order to absorb the radar the material needs to be the proper size in relation to the wavelength. A B-2 bomber is large enough to absorb useful radar frequencies, but F-35 or F-22 isn't. What the F-35/F-22 stealth does get, however, is invisibility in the XHF and higher frequency ranges, which is what is used for radar guided missiles. So they will have a major advantage against ground and air launched long range missiles. The F-22 also has good infrared suppression, which protects it against infrared guided missiles. F-35s have a large IR signature, so they are probably not much better then other US jets. Traditionally speaking it's IR weapons that have caused losses for USA airplanes in modern times. At VHF and lower frequencies the F-22 and F-35 can be detected, but those radars don't offer enough resolution to make them particularly useful for missiles. People suspect that with multiple angles and computer algorithms it may be possible to target a jet that way, but who knows. So if you were Russia and you detected something with VHF long range radar and then you pointed a shorter range XHF radard at it... and nothing shows up then you can be reasonably certain that it's a American stealth fighter jet. That doesn't mean they can do much about it, though. To combat this it is suspected that Americans use a technique that involves 'ghosting' commercial airliner traffic to mask the signatures of their jets against the lower frequency, longer range, radar.
- SEJeff 7y ago
  Israel in fact recently did this in Syria and succesfully targeted the Russian S200 and S300 systems. https://www.bbc.com/news/world-europe-45556290 https://www.bbc.com/news/world-europe-45556290
- zeristor 7y ago
  According to Wikipedia, most recently shot down aircraft have been helicopters falling to small arms, or course Wikipedia is dependent on what people write, but as far as I can tell there aren't that many jets being shot down by IR missiles. Unless that is your point of course https://en.wikipedia.org/wiki/List_of_aircraft_shootdowns#Iraq_War_(2003%E2%80%932011) https://en.wikipedia.org/wiki/List_of_aircraft_shootdowns#Ir...
SEJeff 7y ago
There are two types of radar for virtually everything air defense. The first type searches the entire skies and is for finding aircraft. Networked versions of this are much harder for stealth aircraft to hide from entirely however they have the radar signature of small birds. The S400 and upcoming S500 from Russia is an excellent version of this, but is itself vulnerable to electronic warfare countermeasures. Turning the sensitivity down low enough to detect small birds makes it impossible to use the radars from a practical sense. The second type of radar has an extremely narrow beam and is for targeting. This is the radar that locks onto a plane to direct missiles at it to shoot it down. This is the one that stealth aircraft pretty much entirely defeat. So in short, they can see the planes on occasion, and try to lock, but can't get a target lock. When they try, the stealth airplanes will often release rf tracking missiles and blow them up. I was a UAV (civilian term: "drone") pilot of the Shadow 200 TUAV in the US Army circa 2001-2005 and Iraq 2003-2004. The Shadow 200 TUAV was what was deemed "effective stealth" in that it had composite material with low radar signature and radar absorbing paint. The exhaust was dampened and came out about 1" from the propeller on the top so unless you were flying above, the thermal footprint was miniscule. We did some drills with our own Patriot air defense units and they said they had to set their radars so low they were picking up big birds. They also told us that simply wasn't possible to do in wartime.
- mjevans 7y ago
  Using an AI as a 4th dimensional filter to look for things like "birds flying at highly un-natural speeds" or to at least filter out the ones plausibly flying at natural speeds seems likely to be a current topic of current or already completed defense technology. It seems obvious enough that I feel like every competent military has already considered it.
- Terr_ 7y ago
  As a side-note, Towed Decoys are pretty cool too: > An aircraft-mounted control unit sends the specific signals to the decoy over a fiber-optic line. Once at the decoy, those signals are translated into radio frequency emissions. [...] For instance, the decoy can first try to generally jam a radar that is in search mode, then it can try to attack it directly to break its lock once it locks on. Then, if a missile locks on in flight, the decoy can instantly turn into a juicy target, or even targets, misdirecting the missile away from the aircraft. https://www.thedrive.com/the-war-zone/27185/f-35s-most-sinister-capability-are-towed-decoys-that-unreel-from-inside-its-stealthy-skin https://www.thedrive.com/the-war-zone/27185/f-35s-most-sinis...
Algent 7y ago
I'm convinced it is less and less possible (for countries using modern tech). Long range radars maybe still don't get high precision reading but short range ones can definitely see enough to get a lock.
JustSomeNobody 7y ago
I don't see how. Surely there are multiple ways to look for these aircraft. They disturb the air as they fly. They do give off some heat. They do reflect some radar. A combination of sensors/radar should be able to find them.
johngalt 7y ago
Imagine you are out at night with a flashlight. Trying to detect a car driving towards you. One car is painted like a fire truck with reflectors. The other is matte black/gray. The first one you will be able to spot much earlier and determine things like speed/direction much more clearly. Not to mention that the driver of both cars will see you and your flashlight before you detect them. It is not that planes are invisible to radar. It is that they can make it much more difficult for that radar flashlight to detect them at long range and/or determine their exact speed and heading.
Yizahi 7y ago
The point is not to hide "always" but to hide until enemy SAM is in range of your air-to-ground missiles/bombs and they don't see you yet. It is only one of the factors in whole picture and it does give certain advantage.
nyc_pizzadev 7y ago
Why is there no mention of IR (heat) radar? As far as I know, its impossible to hide a jet engine heat signature. Thermodynamics 101. This is especially true when you are looking up and the thermal background is pretty much black space.
- tropo 7y ago
  It's possible. The heat signature is well-hidden on the B-2, YF-23, F-117, and A-10. Yes, from the perspective of ground-launched IR-seeking missiles, the A-10 is actually stealth. The tail wraps around the engines as seen from many angles on the ground. Generally, it also helps to fly toward the enemy. This is a bit of extra incentive to not wimp out and flee. :-) The F-35 is a bit of a failure with the heat signature. The tail heats up from the engine exhaust. There are prohibited maneuvers that damage the tail due to heat. Aircraft don't have to be perfect about heat signatures. They aren't in a cold vacuum, and the enemy isn't flying the James Webb Space Telescope.
- Majromax 7y ago
  > Why is there no mention of IR (heat) radar? As far as I know, its impossible to hide a jet engine heat signature. The heat signature of what, the exhaust? That's very low density, so emissions from the exhaust itself will be negligible. The plane itself will emit black-body radiation, but that is based on the skin temperature, not the temperature of any interior engine parts. In the meantime, all of this is for passive detection, so at a distance you'd be asking for the detector to pick an at-best-tiny signal out of the entire sky. Moreover, clouds are opaque.
  - nyc_pizzadev 7y ago
    The heat signature of the engine, which in part is connected to the entire plane. Burning that much jet fuel produces a tremendous amount of energy. You literally have a glowing ball of energy streaking thru a vast void of no to low energy. Clouds have heat, but not at the huge concentration a fighter jet has. I guess you have flares, but now its an "AI" problem of choosing the right target.
crimsonalucard 7y ago
I've heard certain types of radar can detect everything nowadays. Nothing is truly stealth and it's just a gimmick. This was from that guy who completely criticized the F-35, Pierre Sprey. I'm not an expert. I really want to hear the opinions of experts on this topic.
- barkingcat 7y ago
  You won't find these kinds of experts on this particular forum. Maybe go find an aviation or military specific engineering discussion group? Hacker News is the worst place for this kind of topic. Have you noticed that no-one applies formulas and calculations of any type in this particular discussion yet? Physically you can calculate the radar profile of all of these types of planes, and there are engineering spec sheets (albeit some are classified, but there's enough data out there for educated estimates) But everyone is talking in terms of "like a bird" or "almost like background radiation" etc. I'd suggest going elsewhere to engage experts on this topic.
- greedo 7y ago
  Sprey, for all his accolades is also the person who thought the F-15/F-14 were mistakes (the former arguably the most successful jet fighter ever created), and didn't want the F-16 expanded into a multirole fighter.

joyjoyjoy 7y ago

No, it isnt. No aircraft can be stealthy by definition. You can see it, right? There are tons of detections methods, wavelengths and other stuff you can scan the sky with. And you may be able to evade some of them. In the end you buy low speed, low dog fighting capability, low payload and huge maintenance time for the bet that you may or may be not invisible. If your bet fails, it comes at a high costs since your one trick pony failed.

imtringued 7y ago

It is effective against missiles that are equipped with very small radars. Since new aircraft like the F-35 are equipped with strong ECM and no longer require dedicated jamming support aircraft you also cannot use the much wider radar of the aircraft to guide the missile. This means we are back to using infrared missiles which can be avoided by flares.

mysterydip 7y ago

Detection isn't the issue as much as determining what is clutter and what isn't. When you reduce your signal to the level of noise, you can go undetected a lot of the time.

Sharlin 7y ago

It is not about being confused with a bird, but simply about the fact that things that are less reflective (whether due to size, material, or geometry) are able to get closer before crossing the signal:noise threshold.

b_tterc_p 7y ago
How hard is it to generate noise?
- taneq 7y ago
  Without being noticed? Noise where there should be none is a signal.
  - b_tterc_p 7y ago
    True, but if your enemy is expecting you to send a plane one random day in August, streaming constant noise on EVERY day in August is going to cost them resources and make it easier on the day that you pick.

raverbashing 7y ago

Primary radar is bad at determining speed, especially when the aircraft is not flying directly towards or away from it and even more difficult with a reduced radar signature. (ATC relies on secondary radar - that is, transponders)

atonse 7y ago

This is likely moot nowadays with drone technology, stealth drones, and modern cruise missiles. They're far more likely to be deployed to take out anti-air defenses before even these aircraft come in.

monkeynotes 7y ago
I often think about what use the modern fighter jet is. I'd be interested to know exactly what role they really play and why a F22 would be deployed risking a pilots life vs. a drone. Maybe the F22 has a bigger payload or more precision?
- detritus 7y ago
  Situational awareness, jamming and reaction/ping times spring to mind immediately as being areas where having meat in the seat will remain advantageous for a while to come.
  - jacobush 7y ago
    I think situational awareness will remain very important to small to medium size air forces. I can't help but think of the Swedish Air Force. The idea was to be able to strike very hard if absolutely necessary. Otherwise, the air force would not be deployed at all. We never expected to operate in air superiority conditions. It was always about inflicting maximum damage to an invader. In such a situation you are already accepting heavy casualties and higher risk to the pilots seems more palatable if that means more room to improvise to achieve the objective.
SEJeff 7y ago
This is false. The US military still does SEAD missions with manned fighter bombers. We have no stealth drones capable of this yet. We also don't have hypersonic cruise missiles (yet), so modern cruise missiles aren't great against advanced air defense. A tomahawk flies a lot slower than an F22 as an example and isn't stealthy at all. Any near peer adversary, or one using near peer anti-air (so anything from Russia or China or imported from either) can knock out most of our cruise missiles provided we don't confuse it with ELINT / jamming. https://en.wikipedia.org/wiki/Suppression_of_Enemy_Air_Defenses https://en.wikipedia.org/wiki/Suppression_of_Enemy_Air_Defen...

natermer 7y ago

No. Not a F-22 or F-35 are unlikely to actually be invisible. A B-2 bomber has a better chance. The talking heads from the military may talk about 'invisibility', but they are full of shit. Just propaganda for the tax payer. The problem is the physical size of the jet. In order to absorb the radar the material needs to be the proper size in relation to the wavelength. A B-2 bomber is large enough to absorb useful radar frequencies, but F-35 or F-22 isn't. What the F-35/F-22 stealth does get, however, is invisibility in the XHF and higher frequency ranges, which is what is used for radar guided missiles. So they will have a major advantage against ground and air launched long range missiles. The F-22 also has good infrared suppression, which protects it against infrared guided missiles. F-35s have a large IR signature, so they are probably not much better then other US jets. Traditionally speaking it's IR weapons that have caused losses for USA airplanes in modern times. At VHF and lower frequencies the F-22 and F-35 can be detected, but those radars don't offer enough resolution to make them particularly useful for missiles. People suspect that with multiple angles and computer algorithms it may be possible to target a jet that way, but who knows. So if you were Russia and you detected something with VHF long range radar and then you pointed a shorter range XHF radard at it... and nothing shows up then you can be reasonably certain that it's a American stealth fighter jet. That doesn't mean they can do much about it, though. To combat this it is suspected that Americans use a technique that involves 'ghosting' commercial airliner traffic to mask the signatures of their jets against the lower frequency, longer range, radar.

SEJeff 7y ago
Israel in fact recently did this in Syria and succesfully targeted the Russian S200 and S300 systems. https://www.bbc.com/news/world-europe-45556290 https://www.bbc.com/news/world-europe-45556290
zeristor 7y ago
According to Wikipedia, most recently shot down aircraft have been helicopters falling to small arms, or course Wikipedia is dependent on what people write, but as far as I can tell there aren't that many jets being shot down by IR missiles. Unless that is your point of course https://en.wikipedia.org/wiki/List_of_aircraft_shootdowns#Iraq_War_(2003%E2%80%932011) https://en.wikipedia.org/wiki/List_of_aircraft_shootdowns#Ir...

SEJeff 7y ago

There are two types of radar for virtually everything air defense. The first type searches the entire skies and is for finding aircraft. Networked versions of this are much harder for stealth aircraft to hide from entirely however they have the radar signature of small birds. The S400 and upcoming S500 from Russia is an excellent version of this, but is itself vulnerable to electronic warfare countermeasures. Turning the sensitivity down low enough to detect small birds makes it impossible to use the radars from a practical sense. The second type of radar has an extremely narrow beam and is for targeting. This is the radar that locks onto a plane to direct missiles at it to shoot it down. This is the one that stealth aircraft pretty much entirely defeat. So in short, they can see the planes on occasion, and try to lock, but can't get a target lock. When they try, the stealth airplanes will often release rf tracking missiles and blow them up. I was a UAV (civilian term: "drone") pilot of the Shadow 200 TUAV in the US Army circa 2001-2005 and Iraq 2003-2004. The Shadow 200 TUAV was what was deemed "effective stealth" in that it had composite material with low radar signature and radar absorbing paint. The exhaust was dampened and came out about 1" from the propeller on the top so unless you were flying above, the thermal footprint was miniscule. We did some drills with our own Patriot air defense units and they said they had to set their radars so low they were picking up big birds. They also told us that simply wasn't possible to do in wartime.

mjevans 7y ago
Using an AI as a 4th dimensional filter to look for things like "birds flying at highly un-natural speeds" or to at least filter out the ones plausibly flying at natural speeds seems likely to be a current topic of current or already completed defense technology. It seems obvious enough that I feel like every competent military has already considered it.
Terr_ 7y ago
As a side-note, Towed Decoys are pretty cool too: > An aircraft-mounted control unit sends the specific signals to the decoy over a fiber-optic line. Once at the decoy, those signals are translated into radio frequency emissions. [...] For instance, the decoy can first try to generally jam a radar that is in search mode, then it can try to attack it directly to break its lock once it locks on. Then, if a missile locks on in flight, the decoy can instantly turn into a juicy target, or even targets, misdirecting the missile away from the aircraft. https://www.thedrive.com/the-war-zone/27185/f-35s-most-sinister-capability-are-towed-decoys-that-unreel-from-inside-its-stealthy-skin https://www.thedrive.com/the-war-zone/27185/f-35s-most-sinis...

Algent 7y ago

I'm convinced it is less and less possible (for countries using modern tech). Long range radars maybe still don't get high precision reading but short range ones can definitely see enough to get a lock.

JustSomeNobody 7y ago

I don't see how. Surely there are multiple ways to look for these aircraft. They disturb the air as they fly. They do give off some heat. They do reflect some radar. A combination of sensors/radar should be able to find them.

johngalt 7y ago

Imagine you are out at night with a flashlight. Trying to detect a car driving towards you. One car is painted like a fire truck with reflectors. The other is matte black/gray. The first one you will be able to spot much earlier and determine things like speed/direction much more clearly. Not to mention that the driver of both cars will see you and your flashlight before you detect them. It is not that planes are invisible to radar. It is that they can make it much more difficult for that radar flashlight to detect them at long range and/or determine their exact speed and heading.

Yizahi 7y ago

The point is not to hide "always" but to hide until enemy SAM is in range of your air-to-ground missiles/bombs and they don't see you yet. It is only one of the factors in whole picture and it does give certain advantage.

nyc_pizzadev 7y ago

Why is there no mention of IR (heat) radar? As far as I know, its impossible to hide a jet engine heat signature. Thermodynamics 101. This is especially true when you are looking up and the thermal background is pretty much black space.

tropo 7y ago
It's possible. The heat signature is well-hidden on the B-2, YF-23, F-117, and A-10. Yes, from the perspective of ground-launched IR-seeking missiles, the A-10 is actually stealth. The tail wraps around the engines as seen from many angles on the ground. Generally, it also helps to fly toward the enemy. This is a bit of extra incentive to not wimp out and flee. :-) The F-35 is a bit of a failure with the heat signature. The tail heats up from the engine exhaust. There are prohibited maneuvers that damage the tail due to heat. Aircraft don't have to be perfect about heat signatures. They aren't in a cold vacuum, and the enemy isn't flying the James Webb Space Telescope.
Majromax 7y ago
> Why is there no mention of IR (heat) radar? As far as I know, its impossible to hide a jet engine heat signature. The heat signature of what, the exhaust? That's very low density, so emissions from the exhaust itself will be negligible. The plane itself will emit black-body radiation, but that is based on the skin temperature, not the temperature of any interior engine parts. In the meantime, all of this is for passive detection, so at a distance you'd be asking for the detector to pick an at-best-tiny signal out of the entire sky. Moreover, clouds are opaque.
- nyc_pizzadev 7y ago
  The heat signature of the engine, which in part is connected to the entire plane. Burning that much jet fuel produces a tremendous amount of energy. You literally have a glowing ball of energy streaking thru a vast void of no to low energy. Clouds have heat, but not at the huge concentration a fighter jet has. I guess you have flares, but now its an "AI" problem of choosing the right target.

crimsonalucard 7y ago

I've heard certain types of radar can detect everything nowadays. Nothing is truly stealth and it's just a gimmick. This was from that guy who completely criticized the F-35, Pierre Sprey. I'm not an expert. I really want to hear the opinions of experts on this topic.

barkingcat 7y ago
You won't find these kinds of experts on this particular forum. Maybe go find an aviation or military specific engineering discussion group? Hacker News is the worst place for this kind of topic. Have you noticed that no-one applies formulas and calculations of any type in this particular discussion yet? Physically you can calculate the radar profile of all of these types of planes, and there are engineering spec sheets (albeit some are classified, but there's enough data out there for educated estimates) But everyone is talking in terms of "like a bird" or "almost like background radiation" etc. I'd suggest going elsewhere to engage experts on this topic.
greedo 7y ago
Sprey, for all his accolades is also the person who thought the F-15/F-14 were mistakes (the former arguably the most successful jet fighter ever created), and didn't want the F-16 expanded into a multirole fighter.