SAC 'Divine Eagle' HALE AEW UAV

[VH]

I think it was a claim made by the manufacturer, if I remember correctly. Obviously they're not going to release the actual data to just anyone, maybe if one posed as a nation's defense force official interested in buying the radar they would shed more light.

That said, UHF and VHF and long band radars do tend to have better anti stealth properties. Much as been made of E-2D's expected ability to be more effective against steatlhy targets compared to previous radars.

I figured that this detection of an F-22 was a 'claim' made that had little or no verification. Unlike the various stealth projects struggling to come into operational existence, F-22 was designed to have all aspect stealth. Others like J-20 and Russian T-50 seem to be optimized for stealth in the forward quarter.


What I would be interested in finding out is how did the Chinese manufacturer KNOW that these were F-22's its radar, the JY-26 Skywatch ,was tracking? Further F-22, B-2 and others have two modes: Peace time and war time. In peace time stealthy aircraft like F-22 augment their signature with a radar reflector so that it can be seen by commercial radars. Maybe that is what this Skywatch radar saw?


Finally it would seem like the power requirements for a radar powerful enough to track stealthy aircraft would be more than this Divine Eagle would be able to generate with its all the other systems packed into its air frame. That radar needs alot of juice!

 

[Blitzo]

I figured that this detection of an F-22 was a 'claim' made that had little or no verification. Unlike the various stealth projects struggling to come into operational existence, F-22 was designed to have all aspect stealth. Others like J-20 and Russian T-50 seem to be optimized for stealth in the forward quarter.

I think the point of long band radar like UHF and VHF radars is that they can detect stealthy aircraft shaped against X band radar (like F-22 and other stealthy fighters like F-35, J-20, T-50) regardless of which position they're displaying to the radar in question... in other words even all aspect stealth is potentially vulnerable to detection.



that doesn't make stealth obsolete of course, because most fighter FCRs still operate in X band, but I do personally think the proliferation of UHF band radar by all states in coming years will reduce the effectiveness of radar stealth for all nations either producing or seeking to produce stealth fighters, compared to previous years.

What I would be interested in finding out is how did the Chinese manufacturer KNOW that these were F-22's its radar, the JY-26 Skywatch ,was tracking? Further F-22, B-2 and others have two modes: Peace time and war time. In peace time stealthy aircraft like F-22 augment their signature with a radar reflector so that it can be seen by commercial radars. Maybe that is what this Skywatch radar saw?

Are you talking about Luneburg lenses?
Possible, but I doubt it. For one, if an experienced radar manufacturer was making these claims I can't imagine they'd make such a primitive mistake like mistaking a stealth fighter with a Luneburg lens as a stealth fighter in operational configuration, especially if the anti stealth properties are actually the selling point of this radar. I'd also expect the Korean peninsula is well monitored by Chinese radar and can compare notes on the performance of differing radar against different targets.
There are also some accounts that JY-26 detected F-22s during military exercises, which further makes me wonder if Luneburg lenses would be deployed during an exercise.
I'm also not sure if F-22s during normal operations would even fly with Luneburg lenses, I imagine only fairly unique situations would prompt such a need. Korea is also quite a "hot-zone" so to speak, so I'm not sure if RCS enhancing measures would be sensible for F-22 deployments to that area.


But of course this is all speculation, we have no idea if they actually did detect or track F-22s over korea.
For all we know they might be knowingly talking out of their backside, but it isn't really the nature of Chinese manufactuers to lie about export-ready products. More importantly it's not exactly a secret that UHF and VHF band radars are more effective against stealthy aircraft, now paired with modern AESA technology, so if such a radar has been developed in JY-26 (and no doubt a variety of other similar products for domestic use not cleared for export) it shouldn't come as too much of a surprise.

Finally it would seem like the power requirements for a radar powerful enough to track stealthy aircraft would be more than this Divine Eagle would be able to generate with its all the other systems packed into its air frame. That radar needs alot of juice!

No doubt that is why Divine Eagle is so large, however you seem to be under the impression that UHF of VHF band radars use sheer power output to detect stealthy aircraft. I don't think that is the case. Now, I'm not too knowledgeable about radars, but I think the anti stealth properties of certain radars arise from the nature of the band the radar is operating in and the nature of the stealth techniques of the target. Long band radars have always been said to have good properties against stealth aircraft, but it's only with recent phased array technology that the band has become more operationally practical in a surveillance role.

For instance, E-2D's APY-9 UHF radar is on a fairly small platform yet it is creating much interest in its supposed anti stealth properties. Brute power isn't the question here, but rather the band the radar operates in, the software behind the radar and the type of array itself.
(a good starter article to read on the matte: http://news.usni.org/2014/06/09/u-s-navys-secret-counter-stealth-weapon-hiding-plain-sight )

Also, newer arrays with newer materials technology can also radiate with more power while using less electricity (such as GaN vs GaA).

 

[quellish]

I think the point of long band radar like UHF and VHF radars is that they can detect stealthy aircraft shaped against X band radar (like F-22 and other stealthy fighters like F-35, J-20, T-50) regardless of which position they're displaying to the radar in question... in other words even all aspect stealth is potentially vulnerable to detection.

No, not at all.
The point of reduced observables is to increase survivability by reducing the engagement range of the bad guy's weapons. It is not to be "invisible" or to avoid detection. A bad guy can't harm a very low observable aircraft until it is too late to do anything about it.


Low frequency radars may actually have a difficult time with a target that is showing a "long" aspect to the radar. For example, seeing an F-22 from the side aspect may present an electrically "long" target to the low frequency radar, which may have a much less energetic return.


Different frequencies are useful for different things. A lower frequency has longer range for a given power output, but has much less "resolution". AM radio is lower frequency but it's not great for music - but it can travel a long distance.

Long band radars have always been said to have good properties against stealth aircraft, but it's only with recent phased array technology that the band has become more operationally practical in a surveillance role.

That's not the case at all. Low frequency radars have been used for early warning for a very, very long time. They aren't good for much else. A phased array makes it *easier* for them to send more energy down a single bearing, but in practice this does not affect the outcome as much as some would like to believe. At the end of the day if you screwed up your mission planning a low frequency radar could detect you, but still couldn't do anything to harm you.

 

[ouroboros]

At least nobody can claim it's a copy of something Western or Russian, you've got to give them that

There was a configuration under study very early in the Sensorcraft effort that was *very* similar but sensitive for historical reasons - there was design history shared with another program.

Don't leave us hanging like that! Particularly if Divine Eagle potentially has its own heritage with Sensorcraft design data...

 

[Blitzo]

No, not at all.
The point of reduced observables is to increase survivability by reducing the engagement range of the bad guy's weapons. It is not to be "invisible" or to avoid detection. A bad guy can't harm a very low observable aircraft until it is too late to do anything about it.

Low frequency radars may actually have a difficult time with a target that is showing a "long" aspect to the radar. For example, seeing an F-22 from the side aspect may present an electrically "long" target to the low frequency radar, which may have a much less energetic return.

Different frequencies are useful for different things. A lower frequency has longer range for a given power output, but has much less "resolution". AM radio is lower frequency but it's not great for music - but it can travel a long distance.

Right, though the main point of my post is that different bands have different properties and the UHF and VHF bands are more effective against current fighter sized stealth aircraft, and that the utility of UHF and VHF radar against stealthy fighter sized aircraft isn't necessarily dependent on "all aspect stealth" rather than the physics of that particular kind of radar. What VH said implied that "all aspect stealth" would cause a stealthy aircraft to be stealthy from all directions, while my reply said that VHF and UHF radar could still be effective against an "all aspect" stealthy aircraft regardless of direction, as well as only say the stealthy frontal aspects of non "all aspect" stealthy aircraft.

Also, I never said that stealth aircraft were designed to be invisible, and at the end of my post I did add the caveat that stealth is still useful against the FCRs of current combat aircraft... not to mention higher frequency radar in general.

That's not the case at all. Low frequency radars have been used for early warning for a very, very long time. They aren't good for much else. A phased array makes it *easier* for them to send more energy down a single bearing, but in practice this does not affect the outcome as much as some would like to believe. At the end of the day if you screwed up your mission planning a low frequency radar could detect you, but still couldn't do anything to harm you.

yes, I'm well aware that low frequency radars have been in use for a long time, however from what I've read on the matter, modern low frequency radars are more capable than older models.
Much has been made of E-2D's APY-9's improvements in utility compared to legacy UHF and VHF radars for instance, and the point I was getting at is more modern UHF and VHF radars should be more operationally useful than older types.


Is any of this incorrect? My understanding of the topic is not very good at all and I'd appreciate any info you'd care to impart.


Also, regarding the underlined part, I'd be interested if you have further info on just how much improvements modern active phased arrays and other advancements in technology make UHF and VHF radars more effective (against stealthy targets or non-stealthy targets or both). Such as improvements in resolution, namely.

 

[DrRansom]

Why would the Divine Eagle get pushed into contested airspace? Wouldn't it be almost as useful to have the Divine Eagle as a high altitude / mobile / survivable Distant Early Warning radar?

If China expects its fixed radar sites to be killed on the opening hours of a war, then a Divine Eagle lets the Chinese reconstitute that long range radar line. That mission doesn't require the UAV to move into contested airspace where it will require heavy escort.

Though, the Divine Eagle should behoove the US to develop an AWACs-killer AAM.

 

[Blitzo]

Why would the Divine Eagle get pushed into contested airspace? Wouldn't it be almost as useful to have the Divine Eagle as a high altitude / mobile / survivable Distant Early Warning radar?

If China expects its fixed radar sites to be killed on the opening hours of a war, then a Divine Eagle lets the Chinese reconstitute that long range radar line. That mission doesn't require the UAV to move into contested airspace where it will require heavy escort.

Though, the Divine Eagle should behoove the US to develop an AWACs-killer AAM.

I think the idea is for Divine Eagle to also serve in an offensive kill chain for long range strike weapons, meaning it'll at least have to operate beyond China's own territorial airspace. Say, a few hundred km out.


By nature this system should be multirole so it can serve in a defensive role as well, against low flying targets like cruise missiles, but tracking opposing land and surface targets and coordinating strikes were also major tasks suggested by the original concept paper

 

[Deino]

Finally ... ???

 

[totoro]

So it doesnt have a large front wing? Just a small one in between the fuselages? And main wing is almost at yhe rear edge of the plane? So center of mass is also there? Thats a mighty peculiar arrangement... is the ront half of the fuselages going to be empty, devoid of fuel and equipment???

 

[Blitzo]

So it doesnt have a large front wing? Just a small one in between the fuselages? And main wing is almost at yhe rear edge of the plane? So center of mass is also there? Thats a mighty peculiar arrangement... is the ront half of the fuselages going to be empty, devoid of fuel and equipment???

I doubt it will be empty, but it probably will be quite a bit lighter than the aft portion of the fuselages.


And we don't quite have know how large the front wing is yet, it may well be sizable enough to balance things out.

 

[Deino]

 

[totoro]

Shadow on the ground shows the front wing is positioned right at the front edge of fuselages.

 

[Deino]

Shadow on the ground shows the front wing is positioned right at the front edge of fuselages.

Thanks ! I did not notice that.

 

[overscan (PaulMM)]

yes, and it looks pretty straight.

 

[overscan (PaulMM)]

Sukhoi S-62 HALE UAV for reference. The two fuselages housed radar antennas and were lifting bodies which helped balance lift nicely. An advantage of the design was it allowed allow radar antennas with the greatest length possible compared to the physical size - with a wing in the middle the antenna would be split in two parts, by shifting wing to the rear this is avoided, plus the twin fuselages and central canard means the outward facing antenna can continue to the very end of the nose and not have to stop for a canard control surface. Canted tailfins indicate a concern with RCS.


The Divine Eagle fuselages don't actually look oval in section to me, more like a rounded hexagon. Hard to tell from the pics.

 

[overscan (PaulMM)]

Kind of like this, though my sides seem off a bit (not straight)

 

[Deino]

Yes ... but I think esp. close to the wings the fuselage is even wider ...

 

[overscan (PaulMM)]

I'd like to see more images, but the 3 view certainly seems wrong except at most basic arrangement level.

 

[overscan (PaulMM)]

If it truly is intended to use metric VHF radar, then the fuselages presumably are radar transparent and house loads of yagi arrays.

 

[LowObservable]

In the photo, it looks as if the outer side of the right-hand body is gray and the inside of the left-side body is primed metal. So what is there could be an antenna farm.


Another point is that they are not apparently doing this for aerodynamic/structural reasons because whatever they gain from distributed loading/high AR will be lost on the weight and wetted area of the monster vertical tails.

 

[overscan (PaulMM)]

Yes - and I'm not sure the inner fuselage sides have the same flattened profile. Extremely rough sketch

 

[Deino]

Yes - and I'm not sure the inner fuselage sides have the same flattened profile. Extremely rough sketch

Hey, that's a rough but overall an accurate sketch !

 

[totoro]

if the array goes all the way from the main wing to the "head" of the fuselage, that might allow for a 8-9 long array. To cram a VHF array there, especially considering the vertical thickness of the fuselage - it doesn't seem it'd allow for an useful vhf radar. It'd be very imprecise and it'd basically be a 2d radar.

Housing an uhf array, on the other hand, seems like a much more sensible solution. it'd offer greater length and vertical area than the array in e2 hawkeye, meaning greater resolution in both elevation and azimuth. And UHF should still be very, very useful against most LO aircraft - especially f35 and various cruise missiles.

 

[Deino]

???

 

[FighterJock]

???

And I thought the Global Hawk was big! The Devine Eagle will easily be the biggest UAV ever designed and built. B)

 

[LowObservable]

That aspect ratio looks pretty sporty to me.

 

[sferrin]

???

And I thought the Global Hawk was big! The Devine Eagle will easily be the biggest UAV ever designed and built. B)

Wut?

https://www.youtube.com/watch?v=YqmjKMgE2nQ

 

[sferrin]

I wonder how they plan on keeping this massive, non-stealthy, radiating target from being shot down. Tacit Blue it ain't.

 

[FighterJock]

I wonder how they plan on keeping this massive, non-stealthy, radiating target from being shot down. Tacit Blue it ain't.

A J-20 fighter escort once that plane enters service or only use it to cover Chinese airspace.

 

[LowObservable]

"I wonder how they plan to keep this massive, non-stealthy, radiating target from being shot down."


The Chinese ain't the only ones who should be worrying about that, kid.

 

[sferrin]

"I wonder how they plan to keep this massive, non-stealthy, radiating target from being shot down."


The Chinese ain't the only ones who should be worrying about that, kid.

Please, do elaborate. If you're referring to E-3s then yeah, same concept.

 

[Blitzo]

Please, do elaborate. If you're referring to E-3s then yeah, same concept.

MQ-4Cs and P-8s.... all won't really survive in a contested environment.


At least AEW&C aircraft and AEW UAVs like Divine Eagle can rely on large active radars to stay behind the "front lines" at stand off range. As I've said before, I think the big draw for Divine Eagle is its expected long endurance, being able to keep a powerful active sensor airborne for extended durations without crew fatigue as there is no crew. Being unmanned, I suspect they might be willing to deploy them a little more forward in the battle space compared to manned and thus more valuable AEW&C aircraft as well.

 

[LowObservable]

Also, a UAV can fly a lot higher than any transport-based platform, and for an application like AEW&C with a UAV you get your line-of-sight benefit twice - because if it's like the Israeli CAEW it really needs a huge-capacity LOS datalink, over and above satcoms.

 

[Stargazer]

And I thought the Global Hawk was big! The Devine Eagle will easily be the biggest UAV ever designed and built. B)

Check this one out: http://stargazer2006.online.fr/unmanned/pages/defender.htm

 

[FighterJock]

And I thought the Global Hawk was big! The Devine Eagle will easily be the biggest UAV ever designed and built. B)

Check this one out: http://stargazer2006.online.fr/unmanned/pages/defender.htm

Just checked out the website, its certainly an impressive design

 

[red admiral]

because if it's like the Israeli CAEW it really needs a huge-capacity LOS datalink, over and above satcoms.

I thought CAEW had operators on board rather than these tasks off boarded to the ground?

 

[LowObservable]

It can have ops on board, but they're busy little bunnies. In the presentation I saw, the datalink was an important operating mode.

 

[red admiral]

It can have ops on board, but they're busy little bunnies. In the presentation I saw, the datalink was an important operating mode.

I suppose it makes sense for non-expeditionary operations in a little-contested EM environment. Much like Sweden's Erieye.

 

[latenlazy]

Also, a UAV can fly a lot higher than any transport-based platform, and for an application like AEW&C with a UAV you get your line-of-sight benefit twice - because if it's like the Israeli CAEW it really needs a huge-capacity LOS datalink, over and above satcoms.

Then there's less emphasis on survivability, cost savings, etc., all of which make it easier to build in redundancy into your system.

 

[Flyaway]

Popular Science article on this UAV including speculation on its size. Is that first picture in the article new?

http://www.popsci.com/closer-look-chinas-divine-eagle-drone