Airborne Early Warning & Control: News & Discussion

[Prasad]

It'll be balance beam. Not the idly shaped one.

[brar_w]

This is unlikely to be the radar on the new A319s. They will use a Netra style Balance Beam setup.

Why would they choose to use a balance beam setup, when the objective is to get 360 degree coverage? They have already built the dome and done enough tests on it.

Is mounting a bit smaller dome on A319 would be that much difficult? Anyway they are going to mount a balance beam, so why not a dome??

There are a finite number of choices to get 360 degrees on a NB. You can either go with a lighter and more efficient antenna and radar design which would mean looking to go to something that operates in much lower frequencies than C or S band. This would minimize some weight, and drag penalty. You can reduce the number of antennas and go for a rotadome and see if you can still retain the S band configuration (like go for 1 or 2 antennas). That however means mechanical rotation on top of electronic scanning which adds some weight back and is also not as fast and you have limitations with revisit rates which will be important when tracking more advanced threats in the future. The third is to just structurally beef up the airframe and just live with the penalty which may or may not be acceptable to the IAF (range, persistence and other parameters also matter).

The problem of getting 360 degrees has largely been solved and there is very little you can do on top of what radar OEM's have already done for various configurations. On a NB, you can throw aerodynamics and drag into the wind and just add a really large nose based antenna to extend coverage (you'll probably need a 6 foot antenna at S band at a minimum to keep up with the mission requirements) which the Israelis have done with some of their designs, or you could chose the Tophat endfiring design that Northrop came up with in the early 90s and applied on the E-7 platform (the aim there was to compete with much larger aircraft so they couldn't "live" with high drag and platform performance penalty). Either way, you would probably want to maintain some sort of ballpark performance of what you may expect in other sectors (may be fewer tracks etc). Honestly, given no more Netras are coming, if the IAF can get its hands on half a dozen NB's with the exact same setup then it will be a quantum jump in its capabilities. Later down the road, when it comes time to replace the Phalcons they can consider a Widebody with a larger radar.

[Karan M]

This is unlikely to be the radar on the new A319s. They will use a Netra style Balance Beam setup.

Why would they choose to use a balance beam setup, when the objective is to get 360 degree coverage? They have already built the dome and done enough tests on it.

Is mounting a bit smaller dome on A319 would be that much difficult? Anyway they are going to mount a balance beam, so why not a dome??

Its tested, proven and hence easier to qualify and develop asap. AWACS fly racetrack patterns so the coverage is maintained for a long time, and is only lost for brief periods when aircraft finally turns.

[jamwal]

Netra on Embraer is always called AEW&C while Phalcon is always called AWACS. Netra-MkII on A-319 is being called AEW&C too. What's the difference between the two?

It'll be balance beam. Not the idly shaped one.

Are you sure?

[Karan M]

Yes, its the balance beam one.

AEW&CS usually has a less powerful radar and fewer controllers onboard while the AWACS has a full scale unit and enough people to do full scale battle management. But its a cosmetic difference at best now.

[nam]

Come to think of it, DRDO would probably use the same radar it built for A330. Would use 2 panel instead of the 4 it planned.
Half the weight planned for A330.

So in terms of range, we will not be lacking.

[brar_w]

Come to think of it, DRDO would probably use the same radar it built for A330. Would use 2 panel instead of the 4 it planned.
Half the weight planned for A330.

So in terms of range, we will not be lacking.

Is there any evidence of this (publicly shared info)? It may save antenna weight but you have to also add the hardware for mechanical scanning and you lose the benefits of electronic scanning and adjusting revisit rates against LO or Cruise Missile type targets. It’s doable but one is unlikely to see 1/2 the weight reduction (it will be less as it would require a rotadome).

[nam]

Is there any evidence of this (publicly shared info)? It may save antenna weight but you have to also add the hardware for mechanical scanning and you lose the benefits of electronic scanning and adjusting revisit rates against LO or Cruise Missile type targets. It’s doable but one is unlikely to see 1/2 the weight reduction (it will be less as it would require a rotadome).

Not the rota dome design. I am referring to the 4 antenna panels that were created for the A330 radar.

My assumption is that 2 panels each from this design will be used on the balance beam. So in terms of range & capability you are not missing out much, other than coverage angles.

The A330 radar was S band GaN AESA! Have been under testing for a while now.

[brar_w]

Ah got it. That would depend upon whether the initial A330 antennas were designed to comply with the form factor and the sub-system footprint of the current balance beam array. If not then they would need to design them to be so which is a possibility. At the end of the day they now have a customer who has a schedule so that will likely dictate how ambitious they get with the first few examples.

[Anujan]

"The six AEW&C block two planes would be highly capable than their predecessor NETRA plane and provide 360-degree coverage deep inside the enemy territory during missions. The government is expected to clear the project soon," government sources told ANI.

That indicates a chappati. Not sure though it is DDM-itis.

[ManuJ]

Good news, but this is not the final approval.

While the CCS decision on the C-295 was the budgetary clearance for the actual signing of the contract, the Committee has cleared the “Acceptance of Necessity” (AoN) for the DRDO project, sources in the defence and security establishment told ThePrint.

This means that the DRDO will now be able to issue a “Request for Proposal” (RFP) for further work on the aircraft.

https://theprint.in/defence/modi-govt-o ... re/730697/

[Mort Walker]

Ah got it. That would depend upon whether the initial A330 antennas were designed to comply with the form factor and the sub-system footprint of the current balance beam array. If not then they would need to design them to be so which is a possibility. At the end of the day they now have a customer who has a schedule so that will likely dictate how ambitious they get with the first few examples.

It depends on what DRDO-CABS has done with the balance beam array development. A trade off in terms of aerodynamic loading, maintenance and operating cost vs. radar performance of beam angle resolution, beam power density and clutter suppression capability.

[basant]

The ToT article today was mentioning about A321s and not A319s.

[Aditya_V]

Article again mentions 360 degree coverage

[Karan M]

The proposed model of the Netra MK2 showed a nose end Uttam style installation. Could be two x band arrays at the nose and tail for 360 degree coverage.

[jamwal]

Do the new idli domes rotate like the older generations? I thought that they were stationary now.
BTW, all 3 sources have reported different aircraft. Even A-320 has multiple versions with different sizes.

[nam]

It depends on the design. If there are 2 radar panel, you get a lighter dome. But you need to put in place the rotating mechanism for 360 coverage.

With 3 or 4 panel, no rotation is required. But the dome become heavier, requires larger aircraft or a smaller antenna to keep within the weight limits.

Air India doesn't seem to have many A320. It is either A319 or A321. A321 is much bigger than A319. We will only come to know later on.

[Pratyush]

Do the new idli domes rotate like the older generations? I thought that they were stationary now.
BTW, all 3 sources have reported different aircraft. Even A-320 has multiple versions with different sizes.

Don't know.

Thought Phalcon on IL 76 doesn't.

Also the schematic published by cabs for the A 330 based set showed a device with 3 sided fixed antenna inside the chapati.

If this is a derivative of that set, then it should not rotate. But I just don't know if it's the same set. Or a further implementation of Netra set. Too much confusion.

[Pratyush]

Air India should be having about 15 a 320 from the original Indian airlines connect from the late 80s.

[Prasad]

It will be balance beam configuration. Nothing on the tail. Not quite 360 degree coverage is something IAF is willing to live with given the capabilities of the platform.

[jamwal]

A beam of a 40 m long Airbus seems a bit of waste. Unlike Embraer, most versions of A-320 are big enough for idli, extra power and electronics. Beam antenna makes sense if aircraft is smaller like A-319. Also the idli antenna has been designed and undergone wind tunnel testing in 2017.

All in all, it just seems like idle speculations at this point with so much conflicting information

[brar_w]

What is height and weight of the circular antenna? How does it impact NB performance?

[nam]

A beam of a 40 m long Airbus seems a bit of waste. Unlike Embraer, most versions of A-320 are big enough for idli, extra power and electronics. Beam antenna makes sense if aircraft is smaller like A-319. Also the idli antenna has been designed and undergone wind tunnel testing in 2017.

All in all, it just seems like idle speculations at this point with so much conflicting information

It is not back & white that a idli design gives you the TFTA solution.

Our idli was suppose to have 4 panels. Let's suppose each panel was to have 1000 TRM (as example, 4K overall) within the radius & weight constraint. If I assume the balance beam design can carry the same weight, wouldn't that make one face of the balance able to carry 2000 TRM? If the balance beam can take 3/4 the weigh of idli, then 1500 TRM on each face!

Now the balance beam design now looks more powerful.

The core difference is balance bean places a restriction on the flight path. Not the capability. With the nose based radar, this will be mitigated to some extent. Netra 2 will have a coverage of 300 degrees. So you are really loosing just 60 degree coverage in the rear. This is acceptable if you are getting a more powerful primary radar.

What is the point of 360 degree coverage at 500 KM, when you can potentially get 700KM range at 300 degree?

If you then consider the power factor, having a antenna with more TRM( ability to handle much higher power ratings) then the balance beam become very desirable.

it is all about the design requirements.

[SinghS]

Very valid point Nam. Game is changing with the advent of AESA.

[brar_w]

Our idli was suppose to have 4 panels. Let's suppose each panel was to have 1000 TRM (as example, 4K overall) within the radius & weight constraint. If I assume the balance beam design can carry the same weight, wouldn't that make one face of the balance able to carry 2000 TRM? If the balance beam can take 3/4 the weigh of idli, then 1500 TRM on each face!

Lets approach this a different way. What was the size of the antenna array area allotted to each of the 3 or 4 antennas on the proposed A-330 dome (let's set aside things like power and thermal allotment for now)? What is the antenna array area on the balance beam configuration of the current Netra? Based on my understanding, the Netra has 1280 T/R modules per face.

If the "Idli" isn't all that it is made out to be, why did DRDO invest in creating a multi-antenna system for the proposed A330? Why not use a balance beam since they already had the design in service? There is an inherent advantage of having equally capable arrays dedicated to each sector and these advantages run the entire gamut of AWACS operations whether that is the ATC functionality, early warning, controlling a intercept, supporting cruise missile defense etc etc. You can continue to track a particular target across 360 degrees (with little restrictions on platform placement) and can adjust revisit rates as desired. If you are not SWaP, platform MLW and/or performance constrained, it is amongst the best options for developing an AWACS.

What is the point of 360 degree coverage at 500 KM, when you can potentially get 700KM range at 300 degree?

Where are both of those numbers coming from?

[nam]

There is no denying the advantages of 360 degree coverage, however the earlier design was for A330. The platform probably had the required power availability to meet the service requirements.

DRDO could have designed a smaller idli for A320/A321 however it has decided to go with a balance beam. If you can have a idli for C295, thee is no reason, why you cannot have one for A320/321.

The compromise on coverage indicates, they are definitely seeing some advantages of a balance beam design for a smaller platform. The advantage I can think is to have more TRM (or may be equal to a larger platform) on a balance beam antenna, compared to what they could have in a idli panel, given the weight & size restriction.

The antenna on the AI21 Netra 2 model seems to indicate it is larger than Netra 1. I don't information on the TRM count for the A330 antenna.

Regarding the range numbers, they are just my speculation. Netra 1 has shown search range of 400+. So an antenna with more TRM and larger platform would obviously have more range.

[brar_w]

If you can have a idli for C295, thee is no reason, why you cannot have one for A320/321

What radar does the C-295 carry? What frequency does it operate in? How much does it weigh? What altitude does that platform cruise at, and at which altitude should the radar be capable of performing at at least 80% levels? Answers to these might help with understanding the trades made on that platform and why that may not matter to this particular case. Even the small, carrier compatible E-2D has an "idli". But that's not a comparison point because its operating in the UHF band. The specific question here was taking the existing S-band tri-antenna design and transplanting that on an A-320/19/21. If you go back to my original post I've laid out pretty much all the ways you can get a 360 degree radar capability within the performance dynamics of a NB without severely crippling your platform performance. You have to exercise one of those options and have to create a sensor, and profile (type of antenna design) to meet that platform need. That's really it and there is nothing more that one can hope for within the trade space.

There are a finite number of choices to get 360 degrees on a NB. You can either go with a lighter and more efficient antenna and radar design which would mean looking to go to something that operates in much lower frequencies than C or S band. This would minimize some weight, and drag penalty. You can reduce the number of antennas and go for a rotadome and see if you can still retain the S band configuration (like go for 1 or 2 antennas). That however means mechanical rotation on top of electronic scanning which adds some weight back and is also not as fast and you have limitations with revisit rates which will be important when tracking more advanced threats in the future. The third is to just structurally beef up the airframe and just live with the penalty which may or may not be acceptable to the IAF (range, persistence and other parameters also matter).

Because there are only so many things you can do given performance constraints of the platform, and the locked in choice on the radar, the DRDO could possibly mount the balance beam radar of the existing Netra and mount a smaller, less capable sensor in the nose so that there is no complete gap in frontal coverage (or they could try to mount a single or dual antenna design housed in a dome that employs mechanical rotation). Remember, DRDO had a A-330 based large AWACS sensor in development, and had Netra in service when the decision was made to instead use AI's A320 family aircraft so they have to re-purpose what they already have. If they had the A-320/19/21 as a basis of a clean sheet AWACS then they would have clearly optimized options for that platform. Northrop invented the MESA with its structurally integrated antenna design, and tophat configuration, specifically for allowing a very low drag, high performance sensor that could allow NB's to compete with much larger and more expensive WB based platforms. But then they had time on their side. DRDO will too once they iterate and offer a full replacement to the Phalcon system. There you will see the 3 or four face design mounted on a widebody. The decision to offload AI's airbus aircraft, and the timelines involved seem to be dictate by IAF's urgency to increase AWACS numbers in the fleet. So DRDO is limited in terms of what it can do within the promised/expected schedule. Over time, as IAF needs grow and older platforms need replacement they can deliver more performance that isn't constrained by some of these factors.

[kit]

Do the new idli domes rotate like the older generations? I thought that they were stationary now.
BTW, all 3 sources have reported different aircraft. Even A-320 has multiple versions with different sizes.

Why would it need to rotate if its AESA. aren't the beams steered electronically , also why can't balance beams provide 360 coverage of additional panels are embedded in fuselage, just thinking loud ,

[brar_w]

Why would it need to rotate if its AESA. aren't the beams steered electronically

When you are Space, weight, power, cooling, constrained and yet still want to have the biggest antenna out there (to get the most performance) you can then chose to use both mechanical and electronic scanning so have one large antenna that combines the two to cover targets more efficiently. Advantage is that you get the greatest sectored performance and if you design they system well you can combine MS and ES functions, vary rotation speeds and can track certain targets using both (like tracking a cruise missile using both MS and ES and letting the track dictate mechanical rotation). The disadvantage of this is obviously that you are limited to revisit rates because it still takes several seconds for the antenna to rotate 360 degrees something that is done near instantaneously when electronically scanning.

also why can't balance beams provide 360 coverage of additional panels are embedded in fuselage, just thinking loud

Yes you can have disparate antennas that can be used to cover gaps. Thinking out loud, you will probably need a 5-6 ft S-band antenna in the nose to get something that begins to resemble similar to what you may be seeing in other sectors. You can chose a higher frequency radar but then performance will be more limited but better than not having anything at all.

[KSingh]

Good news, but this is not the final approval.

While the CCS decision on the C-295 was the budgetary clearance for the actual signing of the contract, the Committee has cleared the “Acceptance of Necessity” (AoN) for the DRDO project, sources in the defence and security establishment told ThePrint.

This means that the DRDO will now be able to issue a “Request for Proposal” (RFP) for further work on the aircraft.

https://theprint.in/defence/modi-govt-o ... re/730697/

CCS is final approval but it’s not a contract, hope that comes soon. Will be absolutely fascinating to track this project, by FAR that largest indigenous aviation project ever attempted in India and the kind of capability only the most developed nations have. In-house conversion to a mil-spec platform, that too AEW, I can only think of a handful of other countries that could do the same.


+ NETRA MK.2 will be balance beam, it’ll be a slightly upscaled antenna of the MK.1 but it’ll also have a radar in the nose so FOV limitations won’t be as pronounced, >300* coverage is adequate for most employment scenarios


++ this project has almost nothing to do with the larger 4-panel AWACS(I) effort that’ll be on the AWACS(I), sadly it seems penny pinchers have pushed that product back beyond 2030 despite being targeted to enter service in 2024 (and having DAC approval for the same). Hope this doesn’t mean they’ll order 2 more PHALCONs, that would be despicable.

+++ there won’t be a radar in the tail of NETRA MK.2, in the A319/20 family that’s where the APU exhaust is


+++ almost certainly it’ll be a A319 and not A321 platform they use. The A319 is a very decent choice for this kind of system, the 321 is just a stretched version and considering this thing will only be transporting a handful of crew there’s not much justification for the 321 vs the 319

[basant]

I am unable to get a clear idea as to the difference in range for A321 vis-à-vis A319. Varied sources show higher, as well as lower, ranges for A321. Range being dependent on payload, I wonder how these ranges are computed for civilian variants.

[KSingh]

I am unable to get a clear idea as to the difference in range for A321 vis-à-vis A319. Varied sources show higher, as well as lower, ranges for A321. Range being dependent on payload, I wonder how these ranges are computed for civilian variants.

Of the older 321s the range was less than the 319, later on (and particularly now with the 321XLR) they have extended the range by adding greater fuel capacity (at the cost of some pax seats)

So of the legacy 319s and 321s AI have, the 319s will likely have larger fuel capacity and hence range.

[basant]

So, given the additional drag thanks to the radar mods, it would be better to use A319. Or perhaps the additional room of A321s can be used for higher fuel and hence more range. Hmm...

[ManuJ]

Good news, but this is not the final approval.



https://theprint.in/defence/modi-govt-o ... re/730697/

CCS is final approval but it’s not a contract, hope that comes soon.

No, there will be another CCS approval after the RFP, selection, and contract negotiation stages that will approve the project cost and provide the budgetary support.

[nam]

Model Image of the radar from Ai21. If this model is taken at face value, there seems to be 1920 (160 X 12) TRM on the top. I

[KSingh]

CCS is final approval but it’s not a contract, hope that comes soon.

No, there will be another CCS approval after the RFP, selection, and contract negotiation stages that will approve the project cost and provide the budgetary support.

What other IDDM projects have we seen go through this? This CCS clearance is the clearance to procure not the project sanction afaik. RFP and selection for what? The project is already matured, what is there to select?

A few months ago it was cleared by DAC

The next step is contract signing and the actual work commencing

[SBajwa]

Question for experts

Will the Airbus 319 or 320 modified to have air to air fueling? (It exists in current Netra)

Since Airbus has much bigger range does it needs Air refueling?

[jamwal]

Even the much bigger Boeing 747 used by American President can be refuelled midair. These smaller Airbus can have the system if required. Human factor is likely to be the limiting point, not the possible time in air.

[Mort Walker]

Why would it need to rotate if its AESA. aren't the beams steered electronically

When you are Space, weight, power, cooling, constrained and yet still want to have the biggest antenna out there (to get the most performance) you can then chose to use both mechanical and electronic scanning so have one large antenna that combines the two to cover targets more efficiently. Advantage is that you get the greatest sectored performance and if you design they system well you can combine MS and ES functions, vary rotation speeds and can track certain targets using both (like tracking a cruise missile using both MS and ES and letting the track dictate mechanical rotation). The disadvantage of this is obviously that you are limited to revisit rates because it still takes several seconds for the antenna to rotate 360 degrees something that is done near instantaneously when electronically scanning.

also why can't balance beams provide 360 coverage of additional panels are embedded in fuselage, just thinking loud

Yes you can have disparate antennas that can be used to cover gaps. Thinking out loud, you will probably need a 5-6 ft S-band antenna in the nose to get something that begins to resemble similar to what you may be seeing in other sectors. You can chose a higher frequency radar but then performance will be more limited but better than not having anything at all.

Radar performance is the governing factor. A mechanically scanned antenna in azimuth may limit revist rates, but at the same time it may allow for better low velocity detection and better clutter rejection due to better beam resolution. It just depends on what the mission is. AESA has many advantages in terms of operational reliability and beam adaptability; however, there are times where you need a coherent circular beam that has about 1 degree or less beam width. If you need the latter, than AESA may be a limiting factor. If you can provide more power on a larger airframe, you can pack in more TR elements to overcome beam forming issues. Another approach is to move to C-band at near 5 GHz which has around a 5 cm wavelength, but there may be other RF issues in upconversion and downconversion.

[ManuJ]

What other IDDM projects have we seen go through this? This CCS clearance is the clearance to procure not the project sanction afaik. RFP and selection for what? The project is already matured, what is there to select?

Please read the news article in the original link.

The DRDO will now issue RFP seeking bids for modification for the six passenger aircraft. Since Airbus is the original equipment manufacturer (OEM), the firm is the frontrunner to bag the contract.