Radar - Specs & Discussions

brar_w · Post by **brar_w** » 21 Feb 2015 02:20

Cybaru wrote:You can have upto 9 Aux tanks in the cargo bay in the 737. It can fly upto 11000 KMS non stop in that config. It is plenty enough. If the engines don't produce enough power an APU or two can be added. There is enough room for everything in the 737 sized platform.

For the E-10 sensor the 737 for both the Raytheon proposal and the Northrop proposal could support the power growth requirement provided in the RFI. The sensor power came from the Honeywell turboshaft engine located in the cargo bay (T55-GA-715).

SaiK · Post by **SaiK** » 21 Feb 2015 02:22

10x2 + 30x4 + 22x2
https://twitter.com/livefist/status/568 ... 81/photo/1

Mort Walker · Post by **Mort Walker** » 21 Feb 2015 02:31

I can't tell if this new AWACS is passive or AESA design. The 20 tons in addition includes the weight of the radome and equipment. The maximum load on 767-300 is about 180 tons and A330-300 is about 240 tons. This is probably why DRDO is looking at the A330 or 767. My guess is that if the airframe is mostly composites, it may be more difficult to mount a radome.

Mort Walker · Post by **Mort Walker** » 21 Feb 2015 02:34

brar_w wrote:
Cybaru wrote:You can have upto 9 Aux tanks in the cargo bay in the 737. It can fly upto 11000 KMS non stop in that config. It is plenty enough. If the engines don't produce enough power an APU or two can be added. There is enough room for everything in the 737 sized platform.
For the E-10 sensor the 737 for both the Raytheon proposal and the Northrop proposal could support the power growth requirement provided in the RFI.

Northrup did the original E-3 and E-8 and Raytheon did the sensor suite on the P-8. Of the two companies, Raytheon is the better, but US defense procurement sometimes tries to balance awards so that there is enough competition.

brar_w · Post by **brar_w** » 21 Feb 2015 02:43

Mort Walker wrote:
Northrup did the original E-3 and E-8 and Raytheon did the sensor suite on the P-8. Of the two companies, Raytheon is the better, but US defense procurement sometimes tries to balance awards so that there is enough competition.

Raytheon was the incumbent with years of experience through the P-3. Northrop did not partner with a prime, nor bid as a prime for the P-3 replacement program, they concentrated their resources on the unmanned maritime market. Boeing & Northrop has similar experience with the E-3, E-2 and E-8. Northrop and Raytheon split the bid 50:50 for the radar development for the E-10 family. The sensors that eventually survived the program cancellation are flying on the Global Hawk and the Northrop owned G550 aircraft. Raytheon has teamed with Lockheed Martin for the Jstars recap competition. Given both sensors are likely to perform much better than the sensor they are replacing it would most likely come down to SI and who has a better solution. Boeing has been left by itself unless it tries to negotiate something with Northrop Grumman.

Mort Walker · Post by **Mort Walker** » 21 Feb 2015 02:52

Boeing isn't really in the sensor or radar business and will work with either company as it does today. Without knowing all of the details of the E-10, my guess is that half the sensor suite went to Raytheon and the other half to Northrup. It is possible Boeing may have gotten the user displays stations.

brar_w · Post by **brar_w** » 21 Feb 2015 02:59

Mort Walker wrote:Boeing isn't really in the sensor or radar business and will work with either company as it does today. Without knowing all of the details of the E-10, my guess is that half the sensor suite went to Raytheon and the other half to Northrup. It is possible Boeing may have gotten the user displays stations.

Developing an aircraft and competing for a formal program of record is much more complicated then simply developing a sensor. Only the SI can bid as a prime, and as a result has to bear the most amount of risk and ultimately take home the largest share of the profit. Systems integration is the defining factor if both sensors exceed performance. Northrop is bidding as a System integrator for its offer for the JSTAR recap using a sensor that it developed as a prime (along with raytheon acting as a junior partner). Raytheon did not have any sensor of its own for Australia's Project Wedgetail. They were to tie up with Elta and Integrate the Phalcon sensor on an Airbus Narrow-body. The E-10 se sensor was a joint effort by NG and raytheon but the ownership was Northrop's since it was the prime for that program. They did it together to avoid a costly competition and to pool IRAD resources. Raytheon has not bid as a prime and would rely on Lockheed Martin to act as the SI on their bid. Boeing is left without an exclusive partner therefore would have to offer a SI proposal along with the battle management components. Raytheon has no direct experience in the E-3 or E-8 market that has been controlled by the Boeing/Northrop team for decades. The sensor tech lead for the AWACS family was with Westinghouse which is now Northrop Grumman. Unless Raytheon develops a sensor on its own from scratch they have NO sensor to offer for the E-3 recap program that would follow the E-8 recap sometime between 2020 and 2025.

For most of these competitions the Pentagon has largely let the SI/Primes decide on whom to pick as the sensor supplier. The USAF would not pick Northrop's SI and BM system plans and a sensor from Raytheon (or vice versa)..They pick the best overall product that is a part of the bid. In the case of replacing the JSTARS, both sensors are already in the air and are well understood, it boils down to which Prime has the better (quality and affordability) SI and BMC2 plan. There won't be (and hasn't been for a while) a formal sensor-showdown/fly-off because the real challenge is in integration, and BMC2 concepts given the technology at the sensor level is in production and not in some lab.

Mort Walker · Post by **Mort Walker** » 21 Feb 2015 04:35

brar_w,

Thanks for the information. Northrop's radar division, formerly Westinghouse in Baltimore, was selected for the original E-3 in the early 1970s. Raytheon in Massachusetts also bid on the E-3 radar, but didn't get selected for a variety of reasons. I agree that developing an aircraft and competing for a formal program is more complicated than sensor development. However, treating a radar as just another airborne sensor is misleading as it is the reason for an AWACS. I'm not discounting the importance of the intense work that goes in to SI and BMC2 implementation. In the case of the IAF, the DRDO is doing the SI with a BMC2 plan and radar, but much of the funds, outside of the aircraft, will most likely be spent on integrating just the radar. It is a challenge.

brar_w · Post by **brar_w** » 21 Feb 2015 05:27

The market is not large to sustain 2 OEM's. Going ahead, that could change but Raytheon has yet to give any hint of competing with a product of its own (E-3 recap). The last time proposals were sought (For the RAAF project) Raytheon chose to work with an Elta project and integrate it on an Airbus. Certainly they can do a clean sheet sensor, but most of the development would have to come from internal funding. As far as selecting a sensor, in the JSTARS recap case, both sensors are largely developed and have been demonstrating their capability to the USAF for some years now. They are both expected to exceed the performance requirement. The only interesting thing is that Northrop does not want to tie up with Boeing and has intentions to bid solely for everything from the sensor to the integration and management tasks. Raytheon has not competed in this but for the JSTARS they have a sensor that it developed thanks to USN's funding for the AAS it is largely similar although Northrop has been developing software and algorithm for GMTI tasks for decades and the JSTARS is relevant to that end. The USAF has also to decide whether they want an L Band (USAF and eventually RAAF requirement) or a UHF band AESA like the Navy for harder to detect targets (cruise missiles and stealthy aircraft). The Maritime market is Raytheon's domain (given their P-3 and P-8 heritage) while the Airborne AEW is Northrop's to loose. This extends to the sensor-craft like embedded, conformal apertures..Almost all of that *hush* *hush* research has gone to Northrop thanks to its ability to integrate advanced vehicle designs along with electronics and sensors.

Each company brings its own perspective and expertise. Virtually every advanced airborne radar integration contract of the USAF (AESA) has gone to Northrop and the sensor craft proposals were a big big win for them (most likely flying on the RQ-180 now), whereas Raytheon has been first to reach Gallium Nitride TRL milestone (with northrop not far behind). Northrop has also exceeded performance for its Fighter based AESA's till date while Raytheon has struggled to meet DOTE expectations for the Super Hornet AESA. Of Late Raytheon has won some major contracts thanks primarily to its major push into Gallium nitride that in part was due to tech investments made on the back of not being selected by winning 5th generation primes (Boeing and Lockheed Martin).

In case of the IAF bird, its a first attempt to do the sensor and SI on such a large scale and it is wiser to start off with a wide body and scale down rather then start off with a smaller platform and running into challenges.

Gyan · Post by **Gyan** » 21 Feb 2015 08:05

I think we should go for IL-76 solution but stock up on spares.

Cybaru · Post by **Cybaru** » 21 Feb 2015 08:13

we will probably end up ordering the remaining two on il-76. I wonder if there will be a follow on order for EMB145. Perhaps they should another round of 3 to be delivered in the next two years followed by a new common platform after that.

Dennis · Post by **Dennis** » 21 Feb 2015 11:29

Notes on the AEW projects from the CABS stall:

The AEW radar on the Embraer has a range >450 km for 5 sq.m targets. A total of 8 operator stations. First one done with most tests and will be handed over in June. All tests are done for 5, 2, and 1 sq.m targets.

The AWACS-India project will use the same basic AAAU design with some modifications in a fixed dome housing. Range >600 kms for 5 sq.m targets. >11 operator stations and provision for multiple crews. Parametric studies are being conducted on whether a triangle layout with 3 AAAUs or a square layout with 4 AAAUs is the optimum solution in terms of performance, cost and weight. As of now, it appears that the square layout maybe the one chosen.

Once the antenna design has been completed and realized, then CABS will choose the platform on which the antenna will be mounted. It will be 4-5 years before this can happen.

Karan M · Post by **Karan M** » 21 Feb 2015 13:44

Incredible. That means even LO targets of 0.01 mtr sq class developed by the PRC will be detectable at decent ranges by these platforms.

Karan M · Post by **Karan M** » 21 Feb 2015 13:45

No reason btw why the IAF shouldnt order another 3 AEWC asap.

rohitvats · Post by **rohitvats** » 21 Feb 2015 15:00

Karan M wrote:No reason btw why the IAF shouldnt order another 3 AEWC asap.

Pehle Rafale de do....

(ducks for cover!)

RKumar · Post by **RKumar** » 21 Feb 2015 18:50

Karan M wrote:No reason btw why the IAF shouldnt order another 3 AEWC asap.

I was expecting 7 more units.

rohitvats wrote: Pehle Rafale de do.... (ducks for cover!)

Difficult and troubled purchase but munna is crying without any end in sight. Either GoI swallow bitter pill and sign the deal or munna is going to get a slap from parent

Cybaru · Post by **Cybaru** » 21 Feb 2015 19:16

Dennis wrote:Notes on the AEW projects from the CABS stall:

The AEW radar on the Embraer has a range >450 km for 5 sq.m targets. A total of 8 operator stations. First one done with most tests and will be handed over in June. All tests are done for 5, 2, and 1 sq.m targets.

The AWACS-India project will use the same basic AAAU design with some modifications in a fixed dome housing. Range >600 kms for 5 sq.m targets. >11 operator stations and provision for multiple crews. Parametric studies are being conducted on whether a triangle layout with 3 AAAUs or a square layout with 4 AAAUs is the optimum solution in terms of performance, cost and weight. As of now, it appears that the square layout maybe the one chosen.

Once the antenna design has been completed and realized, then CABS will choose the platform on which the antenna will be mounted. It will be 4-5 years before this can happen.

Dennis,

Thank you for sharing.

Couple of quick questions for you.

1. Any idea for how long these birds manage to stay in air?
2. Any follow on order for EMB145? - CABS Awacs seems to be 4+X number of years away.

8 operators is pretty good. Did they have a model of internal layout?

Karan M · Post by **Karan M** » 21 Feb 2015 23:08

Mort Walker wrote:I can't tell if this new AWACS is passive or AESA design. The 20 tons in addition includes the weight of the radome and equipment. The maximum load on 767-300 is about 180 tons and A330-300 is about 240 tons. This is probably why DRDO is looking at the A330 or 767. My guess is that if the airframe is mostly composites, it may be more difficult to mount a radome.

The new AWACS is an AESA as are all new DRDO radar programs. The LLTR, MPR, AWACS, LRTR-Mk2, LCA FCR etc & the AEW&C and now AWACS radar.

Karan M · Post by **Karan M** » 21 Feb 2015 23:10

rohitvats wrote:
Karan M wrote:No reason btw why the IAF shouldnt order another 3 AEWC asap.
Pehle Rafale de do.... (ducks for cover!)

Hey, I didn't ask for 10.

Those 3 AEW&C should cost as much as only a handful of those Rafales..the R&D costs are paid for.

Karan M · Post by **Karan M** » 21 Feb 2015 23:12

Mort Walker wrote:
Karan M wrote:The DRDO radar is an AESA. The design is likely to be a new one. Its not one of the older MSAs with a large TWT/s or other conventional arrangements.
Are you certain? AESA has limitations of beam width resolution. If I were designing a system, I would want at least 1/2 degree beam width. The antenna may be phased in azimuth and elevation scanning.

Fairly certain, IAF wants AESAs across its platforms & they come with significant advantages over PESAs, not least of which is reliability (graceful degradation). The resolution would be per IAF QSR - raid assessment is fairly decent per reports in the DRDO AESAs. The advantages that these systems bring, have had the IAF ask for a whole sale transition to active radars. Haven't seen any RFI/RFP in recent year/s, mention standard radars & the vendors have also shifted more or less wholesale to AESAs.

JTull · Post by **JTull** » 21 Feb 2015 23:42

Karan M wrote:Incredible. That means even LO targets of 0.01 mtr sq class developed by the PRC will be detectable at decent ranges by these platforms.

Tracking these 0.01 SqMtr targets can be a pain though. With super cruise it might be even more difficult. Depends on how many emitters are slaved to track each potential target. Sensor fusion with IRST might help. We don't have our own stealth aircraft to calibrate these so this will be a long learning curve.

Karan M · Post by **Karan M** » 21 Feb 2015 23:55

The advantage of AESAs (ESAs for that matter) is that they can adapt their dwell times because of the amazing speed at which the beam can be positioned. In short, if you have multiple high priority targets which need more attention, with a MSA, you can only attempt to track closely spaced ones, because the entire antenna needs to be repositioned. With AESAs, you can revisit these targets again & again. Of course, it depends on power, beamwidth, PRF, and frequency band too. But generally, high power, properly implemented AESAs can be useful for tracking LO targets. As regards not having our own stealth aircraft - you don't need stealth aircraft to calibrate. Currently our Lakshya fly with Lunenberg lenses to simulate typical opponent aircraft RCS (in short they artificially boost aircraft RCS). Similarly we can develop targets with low RCS. Clearly, facilities and capabilities/access to same exist, though they are little talked about. Recent AMCA video shows AMCA model in RCS testing as well. LRTR was noted as being able to detect 0.1 Sq Mtr at 600 km. Point is development of sword & shield goes hand in hand, and our biggest advantage is that all these systems are developed within the same overall cluster of labs & organizations which share data & cooperate (As versus political bickering in some other MICs & cross sharing/patent rights issues occur and Govt has to step in). In India, DRDO develops a BM, its also working on SAMs capable of targeting similar systems and then knows how to develop advanced BMs able to dodge BMD and then enhanced BMD likewise and so forth.

Mort Walker · Post by **Mort Walker** » 22 Feb 2015 00:05

For reference in square meters of RCS:

Mig21 = 3
Su27 = 15
F16 = 5
B1B = 1
Rafale = 1
F35 < 0.1

Mort Walker · Post by **Mort Walker** » 22 Feb 2015 00:13

Karan M wrote:The advantage of AESAs (ESAs for that matter) is that they can adapt their dwell times because of the amazing speed at which the beam can be positioned. In short, if you have multiple high priority targets which need more attention, with a MSA, you can only attempt to track closely spaced ones, because the entire antenna needs to be repositioned. With AESAs, you can revisit these targets again & again. Of course, it depends on power, beamwidth, PRF, and frequency band too. But generally, high power, properly implemented AESAs can be useful for tracking LO targets. As regards not having our own stealth aircraft - you don't need stealth aircraft to calibrate. Currently our Lakshya fly with Lunenberg lenses to simulate typical opponent aircraft RCS (in short they artificially boost aircraft RCS). Similarly we can develop targets with low RCS. Clearly, facilities and capabilities/access to same exist, though they are little talked about. Recent AMCA video shows AMCA model in RCS testing as well. LRTR was noted as being able to detect 0.1 Sq Mtr at 600 km. Point is development of sword & shield goes hand in hand, and our biggest advantage is that all these systems are developed within the same overall cluster of labs & organizations which share data & cooperate (As versus political bickering in some other MICs & cross sharing/patent rights issues occur and Govt has to step in). In India, DRDO develops a BM, its also working on SAMs capable of targeting similar systems and then knows how to develop advanced BMs able to dodge BMD and then enhanced BMD likewise and so forth.

It is a trade off. You can distinguish LO targets, but how well can you discern against clutter? Especially small, slow moving targets near the ground?

SaiK · Post by **SaiK** » 22 Feb 2015 00:14

AMCA < 0.05 [intended]

Cosmo_R · Post by **Cosmo_R** » 22 Feb 2015 00:15

JTull wrote:....
Tracking these 0.01 SqMtr targets can be a pain though. With super cruise it might be even more difficult. Depends on how many emitters are slaved to track each potential target. Sensor fusion with IRST might help. We don't have our own stealth aircraft to calibrate these so this will be a long learning curve.

That's why if the MMRCA deal falls through. An off the shelf order of ~60 JSF makes tactical sense. We get to learn tactics and techniques and to be able to develop countermeasures some 810 years ahead of the PAK/FA/FGFA it it ever gets going.

Karan M · Post by **Karan M** » 22 Feb 2015 00:25

Mort Walker wrote:
Karan M wrote:The advantage of AESAs (ESAs for that matter) is that they can adapt their dwell times because of the amazing speed at which the beam can be positioned. In short, if you have multiple high priority targets which need more attention, with a MSA, you can only attempt to track closely spaced ones, because the entire antenna needs to be repositioned. With AESAs, you can revisit these targets again & again. Of course, it depends on power, beamwidth, PRF, and frequency band too. But generally, high power, properly implemented AESAs can be useful for tracking LO targets. As regards not having our own stealth aircraft - you don't need stealth aircraft to calibrate. Currently our Lakshya fly with Lunenberg lenses to simulate typical opponent aircraft RCS (in short they artificially boost aircraft RCS). Similarly we can develop targets with low RCS. Clearly, facilities and capabilities/access to same exist, though they are little talked about. Recent AMCA video shows AMCA model in RCS testing as well. LRTR was noted as being able to detect 0.1 Sq Mtr at 600 km. Point is development of sword & shield goes hand in hand, and our biggest advantage is that all these systems are developed within the same overall cluster of labs & organizations which share data & cooperate (As versus political bickering in some other MICs & cross sharing/patent rights issues occur and Govt has to step in). In India, DRDO develops a BM, its also working on SAMs capable of targeting similar systems and then knows how to develop advanced BMs able to dodge BMD and then enhanced BMD likewise and so forth.
It is a trade off. You can distinguish LO targets, but how well can you discern against clutter? Especially small, slow moving targets near the ground?

The present crop of AESAs including fighter ones (latter inc. 3 deg beamwidth or above) all claim to be able to track these sort of targets. Anyhow, a decent enough bearing and range estimate is all that is required to either vector in fighters or shoot missiles (from aforesaid fighters) which then have their own dedicated seekers to finish the end game. IMHO, A 7 mtr *2 mtr dia antenna array as on the CABS AWACS should have decent enough resolution to get this sort of job done. The reliability factor is also a big deal because after all, I bet most of the older gen AWACS would need to be grounded if one of those expensive transmitters conked out and a replacement had to be brought in.

brar_w · Post by **brar_w** » 22 Feb 2015 00:40

Mort Walker wrote:For reference in square meters of RCS:

Mig21 = 3
Su27 = 15
F16 = 5
B1B = 1
Rafale = 1
F35 < 0.1

While the requirements of the F-35 RCS have never been made public it had been acknowledged at the time of the competition that the overall goal with the JSF was to produce a at par or slightly inferior RCS number to the F-22 at a fraction of the cost from a sustainment perspective. The goal as documented by the Aviation week article titled " JSF reflection is Golf Ball-Sized" from Feb. 1999 ( by David Fulghum) cited the number to be 0.001 sq. meter for the frontal aspect of the aircraft.

The Publication claimed :

The overall goal of the JSF program is to produce an aircraft with a slightly larger radar signature than that of the new F-22 Raptor at a fraction of the cost. Its radar cross section (RCS) is to be only -30 dB. when looking at the front quarter of the aircraft. That means the overall radar visibility of the aircraft has been reduced to 0.001 sq. meter through the use of shaping, construction materials and skin coatings. An equivalent signature is the radar reflection from a perfectly electrically conducting metal sphere the size of a golf ball.

Fast forward to today - the USAF's top decision maker for tactical fighters has openly stated that the F-35 has a better RCS then the F-22A. While in the past Lockheed and the Joint Program Office was mum on this claiming only that the RCS measurement throughout the testing process has resulted in a superior number compared to the requirement (better) they have since come out publicly as well in claiming that it is the stealthiest aircraft they have ever designed. In fact, they made the statement again just two days ago. This is in part due to the design's evolution and the applications of the F-22 - lessons learned especially in manufacturing to very high tolerances as well the general advance in resilient coatings that were not available for the F-22 (Fiber Mat)..The F-35 also does not have a mach 1.7+ Supercruise performance or the ability to go supersonic in dry thrust at sea level. That makes the job much easier.

Mort Walker · Post by **Mort Walker** » 22 Feb 2015 00:47

Transistor banks and high power microwave tubes are very reliable. Both the U.S. and USSR worked out reliability issues by the late 1970s and neither country has given up on power tubes for defense applications. A 3 degree beam width is not desirable for a surveillance radar IMHO. You can work out the trigonometry at various ranges to see how wide your beam width is. Like I said you make trade offs in design. You may get detection, but velocity and target distinction is also important. In any case, DRDO has probably made the design trade offs. I think a lot of our discussion here is like blind men describing an elephant from the parts we touch.

Mort Walker · Post by **Mort Walker** » 22 Feb 2015 01:02

brar_w wrote:
Mort Walker wrote:For reference in square meters of RCS:

Mig21 = 3
Su27 = 15
F16 = 5
B1B = 1
Rafale = 1
F35 < 0.1
While the requirements of the F-35 RCS have never been made public it had been acknowledged at the time of the competition that the overall goal with the JSF was to produce a at par or slightly inferior RCS number to the F-22 at a fraction of the cost from a sustainment perspective. The goal as documented by the Aviation week article titled " JSF reflection is Golf Ball-Sized" from Feb. 1999 ( by David Fulghum) cited the number to be 0.001 sq. meter for the frontal aspect of the aircraft.

The Publication claimed :

The overall goal of the JSF program is to produce an aircraft with a slightly larger radar signature than that of the new F-22 Raptor at a fraction of the cost. Its radar cross section (RCS) is to be only -30 dB. when looking at the front quarter of the aircraft. That means the overall radar visibility of the aircraft has been reduced to 0.001 sq. meter through the use of shaping, construction materials and skin coatings. An equivalent signature is the radar reflection from a perfectly electrically conducting metal sphere the size of a golf ball.
Fast forward to today - the USAF's top decision maker for tactical fighters has openly stated that the F-35 has a better RCS then the F-22A. While in the past Lockheed and the Joint Program Office was mum on this claiming only that the RCS measurement throughout the testing process has resulted in a superior number compared to the requirement (better) they have since come out publicly as well in claiming that it is the stealthiest aircraft they have ever designed. In fact, they made the statement again just two days ago. This is in part due to the design's evolution and the applications of the F-22 - lessons learned especially in manufacturing to very high tolerances as well the general advance in resilient coatings that were not available for the F-22 (Fiber Mat)..The F-35 also does not have a mach 1.7+ Supercruise performance or the ability to go supersonic in dry thrust at sea level. That makes the job much easier.

Which is why I used less than 0.1 m^2 since we don't know what it is. The number of -30 dB is in units dBsm. I am a bit leery of specs when fighter aircraft have a lower RCS than a butterfly.

brar_w · Post by **brar_w** » 22 Feb 2015 01:11

Mort Walker wrote: Which is why I used less than 0.1 m^2 since we don't know what it is. The number of -30 dB is in units dBsm. I am a bit leery of specs when fighter aircraft have a lower RCS than a butterfly.

LOL..I am only going by what has been claimed and published..To be on the safe side, may as well say that the F35's RCS is less then 1 sq m

Again a dated report (2011 article citing a 2005 report) that does not account for what the ACC boss claimed and Lockheed corroborated.

According to November 2005 reports, the US Air Force states that the F-22 has the lowest RCS of any manned aircraft in the USAF inventory, with a frontal RCS of 0.0001~0.0002 sqm, marble sized in frontal aspect. According to these reports, the F-35 is said to have an RCS equal to a metal golf ball, about 0.0015 sqm, which is about 5 to 10 times greater than the minimal frontal RCS of F/A-22

Much has been improved between the design of the F-22 and the F-35. The F-35 doors for landing gear and equipment, as well as control surface, all have straight lines. The F-35 does not require "saw tooth" openings to divert RF energy. One reason the openings on the F-35 are straight lines is reported to be embedded electrical wires near the edges which interfere with RF signals. The F-35 RAM is thicker, more durable, less expensive and, being manufactured to tighter tolerances compared to that of the F-22. The tighter tolerances means less radar signal can penetrate openings and reflect back to its source. The newer RAM is more effective against lower frequency radars, and maintenance should cost about a tenth that of the F-22 or B-2. Some forms of RAM have electrical plates or layers within the layers of carbon composites.

.

Karan M · Post by **Karan M** » 22 Feb 2015 01:13

Re: the reliability part, because operational conditions would really affect the items. As late as the 90's, western fighters had TWTs conk out after a hundred odd hours of operation (and these were the best ones). AESAs brought in a sea change.

Re BW, was looking around the usual sources Janes etc. Modern FCRs operate with a 3 deg beamwidth but in fact wide variability. Highly capable (in that its been constantly modernized), PAVE series has 2.2 deg. BW. SPY series on naval platforms has around 2 degrees as well. In short, very high resolution radars are niche (1 deg BW radars were x band ones with a range of few nm).. reasonably sized surveillance radars fielded on tactical platforms, mobile trailers (unlike the huge ones above!) make do with much more liberal BWs and are useful enough to direct other assets to the fight to close out the issue. Erieyes - beamwidth (in azimuth and elevation) is 0.7 degrees and 9 degrees, would be similar to ours. The only radars with sub-one degree BWs or even the one degree level are fixed, static tracking radars used for calibration & missile flight testing etc on ranges. In short, everyone seems to be managing with a wide range of BWs.

Mort Walker · Post by **Mort Walker** » 22 Feb 2015 21:42

brar_w wrote:
Mort Walker wrote: Which is why I used less than 0.1 m^2 since we don't know what it is. The number of -30 dB is in units dBsm. I am a bit leery of specs when fighter aircraft have a lower RCS than a butterfly.
LOL..I am only going by what has been claimed and published..To be on the safe side, may as well say that the F35's RCS is less then 1 sq m

Again a dated report (2011 article citing a 2005 report) that does not account for what the ACC boss claimed and Lockheed corroborated.

According to November 2005 reports, the US Air Force states that the F-22 has the lowest RCS of any manned aircraft in the USAF inventory, with a frontal RCS of 0.0001~0.0002 sqm, marble sized in frontal aspect. According to these reports, the F-35 is said to have an RCS equal to a metal golf ball, about 0.0015 sqm, which is about 5 to 10 times greater than the minimal frontal RCS of F/A-22

Much has been improved between the design of the F-22 and the F-35. The F-35 doors for landing gear and equipment, as well as control surface, all have straight lines. The F-35 does not require "saw tooth" openings to divert RF energy. One reason the openings on the F-35 are straight lines is reported to be embedded electrical wires near the edges which interfere with RF signals. The F-35 RAM is thicker, more durable, less expensive and, being manufactured to tighter tolerances compared to that of the F-22. The tighter tolerances means less radar signal can penetrate openings and reflect back to its source. The newer RAM is more effective against lower frequency radars, and maintenance should cost about a tenth that of the F-22 or B-2. Some forms of RAM have electrical plates or layers within the layers of carbon composites.

I think you're misunderstanding what I'm saying and even what the literature is saying. BTW, your link doesn't work.
The RCS of the F35 has been stated as -30 dBsm to less than -40 dBsm. This is head on. A side profile will yield a different result which may be many times as much. Yes, RAM does help and most of it inhibits detection from ground based L band radar. The specifications given for public consumption typically come from testing aircraft in an anechoic chamber using a transmitter with horizontal polarization and testing across a set of frequencies. The best results make it to AW&ST and other propaganda.

We will never know what it is in practice when detection is trying to be done with an airborne platform such as an AWACS that may be using a wide frequency range and different polarization transmission. Now, that said, I am not discounting the great importance of stealth technology.

On a side note. Much of this work is very technically complicated and neither the USAF or USN has the resources to evaluate it, nor are the program management offices technically competent to understand it. The USAF and USN then go about hiring 3rd party companies to evaluate the work of the contractor. It leads to very high costs of a weapon system. This can not be a model for any one else.

brar_w · Post by **brar_w** » 22 Feb 2015 21:55

I think you're misunderstanding what I'm saying and even what the literature is saying. BTW, your link doesn't work.
The RCS of the F35 has been stated as -30 dBsm to less than -40 dBsm. This is head on. A side profile will yield a different result which may be many times as much.

I am not stating that it isn't the best case frontal RCS in fact both the articles mention that explicitly. You could go and confirm with the author of the avWeek article by contacting him.

http://www.google.com/url?sa=t&rct=j&q= ... 5890,d.eXY

There is absolutely no evidence to confirm any of the RCS mentioned by yourself or to confirm that they are in fact anything other than best case - frontal RCS measures (B-1 etc).

The specifications given for public consumption typically come from testing aircraft in an anechoic chamber using a transmitter with horizontal polarization and testing across a set of frequencies. The best results make it to AW&ST and other propaganda.

You can have your own set of theories but the fact still remains that no where has there been any mention of this NOT being anything other frontal RCS. Every link that has claimed this, has explicitly stated that this is the frontal best case RCS. Even the old Janes articles form the late 90's to early 2000's mention this (too lazy to look the up now). There has been absolutely no effort by anyone concerned, either with the program or the OEM to actually claim that the best case RCS measurement is anything but that and no one has tried to imply that it is an all aspect RCS for the aircraft.

The number that was released to AvWeek and subsequently to other media sources was the KPP at the time of the competition. They aren't going to be dumb enough to publish extensive RCS modeling and prototype testing results. They have since not said anything to update what was said about the KPP other then that it was bettered and the later claims that the F-35 is stealthier than the F-22A.

That much is known. However, anyone can seek any sort of detailed information about any specification or claim and choose not to believe something until they are given full unrestricted, declassified access to testing. That is fine as long as it is applied to other programs as well. In that way we cannot claim that the B-2 is VLO.

We will never know what it is in practice when detection is trying to be done with an airborne platform such as an AWACS that may be using a wide frequency range and different polarization transmission. Now, that said, I am not discounting the great importance of stealth technology.

There are multiple aircraft, ground based sensors, radar ranges and chambers that measure the entire spectrum of the RF signature. For the F-35 post DR vehicle this has taken over 3 years to actually explicitly document and compare to the KPP. This is why there is a lag in reporting form the time the KPP's were disclosed (again, best case frontal) to the time the senior ACC officials (such as the head himself) claiming that it has not only beaten the KPP's but exceeds the stealthiness of the F-22A.

Stealth technology is as much bout design as it is about finding out the RCS and optimal signatures against various threats. There is an industrial scale effort in the background that manages that.

On a side note. Much of this work is very technically complicated and neither the USAF or USN has the resources to evaluate it, nor are the program management offices technically competent to understand it. The USAF and USN then go about hiring 3rd party companies to evaluate the work of the contractor. It leads to very high costs of a weapon system. This can not be a model for any one else.

A directorate has existed for over a decade that oversees operations of service owned assets (some open, other secret) and brings in expertise from the academia from time to time to refine the process. Gone are the days when OEM's had exclusive access to their own facilities and expertise and the services relied upon them or contracted them on a case by case basis (as was done during the Have Blue testing).Other RCS facilities have been under government/service control for over 5 decades. .Like everything else the process is always a mixture. Even basic design and refinements are done by the OEM under the management of the larger program manager led team. This doesn't apply just to stealth, RCS etc but also to the basic engineering concerned with the aircraft. Prototype radars are mostly classified but in the past have been custom ordered by the services for their own ranges. Sometimes as in the case of the Lockheed developed VHF radars, it was purchased by lockheed martin after the USAF was done with it so that it could include it in its own company based projects..Other than that, RCS management post testing has been successfully incorporated at the squadron and AEF level since the induction of the F-22. Each aircraft's signature is tracked, monitored and maintained and fed into a database. While relying on a small set of experts was the norm 20 years back, expertise, testing protocols and physical testing hardware has since proliferated to multiple devisions both in the industry and special services run setups.

I'll leave it at that !

As far as it being a model for anyone else - That depends whether anyone else is looking to undertake projects on that scale or not. The stealth infrastructure (and this involves all the testing, evaluating and documenting abilities in addition to the capability to design and produce stealthy designs) exists at the level because there have been investments made since the 70's (in fact earlier) to develop this capability and to maintain a lead over near peer threats with this capability. You can dissect this and write a paper on how to do it better if you please but that would involve access to a lot of things which I seriously doubt exists with anyone outside of the DOD or industry. Btw, there is next to NOTHING known about radar-range modernization and the R&D efforts in the classified budget for complex RCS testing beyond the investments made for the F117 and B-2 systems. One would be naive to think that they haven't ordered custom-prototypes using advanced AESA radars over the last decade when they have spent close to 100 Billion on the USAF classified budget alone in that time frame

Mort Walker · Post by **Mort Walker** » 23 Feb 2015 00:03

Karan M wrote:Re: the reliability part, because operational conditions would really affect the items. As late as the 90's, western fighters had TWTs conk out after a hundred odd hours of operation (and these were the best ones). AESAs brought in a sea change.

Re BW, was looking around the usual sources Janes etc. Modern FCRs operate with a 3 deg beamwidth but in fact wide variability. Highly capable (in that its been constantly modernized), PAVE series has 2.2 deg. BW. SPY series on naval platforms has around 2 degrees as well. In short, very high resolution radars are niche (1 deg BW radars were x band ones with a range of few nm).. reasonably sized surveillance radars fielded on tactical platforms, mobile trailers (unlike the huge ones above!) make do with much more liberal BWs and are useful enough to direct other assets to the fight to close out the issue. Erieyes - beamwidth (in azimuth and elevation) is 0.7 degrees and 9 degrees, would be similar to ours. The only radars with sub-one degree BWs or even the one degree level are fixed, static tracking radars used for calibration & missile flight testing etc on ranges. In short, everyone seems to be managing with a wide range of BWs.

The TWTs in fighter aircraft are subject to much more vibration, space limitation, power supply limitations, and redundancy. For fighter aircraft an AESA design is highly desirable. Scaling it up to for a full blown surveillance radar is not a good example IMHO because there is space for larger tubes and larger power supplies with redundancy. What fails in power tubes like TWTs and klystrons are the needed power supplies for building up a high voltage pulse for 1 MW (or greater) of RF power, and or the power supply for power tube beam focusing solenoid. For an AWACS you could use a solid state transmitter or power tubes. Power tubes have the advantage of creating nice shaped narrow pulses on the order of tens of nano-seconds to resolve targets within 10 meters if needed. Some solid state designs can do this too depending on transmission frequency, but they are heavy too.

AESA has come a long way in the last couple of decades and for the DRDO AWACS it may indeed be a good design choice. Looking at the new DRDO radome, it appears to be 10 m wide by 2 m height. I'm speculating that it has four panels and may be able to generate a relatively narrow beam width (< 1 degree) if frequencies of 5-9 GHz are used. This would be ideal as it would limit water vapor attenuation. It explains why they are looking at the 767 or A330 airframes.

brar_w · Post by **brar_w** » 23 Feb 2015 00:20

^^ I'm unable to recollect the source but somewhere there was a mention that AESA would be the choice for a future RuAF radar. The USAF was developing an AESA for the E-3 replacement, and is going to do the same for the future as well. There seems to be a unanimous opinion around the world (among OEM's offering solutions and services/customers demanding them) with everyone looking to develop such hardware looking towards an AESA solution irrespective of the budget or cost involved.

Mort Walker · Post by **Mort Walker** » 23 Feb 2015 01:24

^^^The idea is to get enough energy on target. Using a fast scanning pencil beam, even a lower power radar can deliver more power density and make not just detection, but provide better velocity information. An AESA solution may be ideal for airborne platforms, but there isn't enough information in the public domain yet about beam width and target resolution using AESA. Given the proliferation of stealth, I suspect the DRDO has been able to design the new AWACS with < 1 degree beam width; and one that can change polarization as well from horizontal, vertical and circular.

brar_w · Post by **brar_w** » 23 Feb 2015 03:02

Mort Walker · Post by **Mort Walker** » 23 Feb 2015 07:06

brar_w wrote: I am not stating that it isn't the best case frontal RCS in fact both the articles mention that explicitly. You could go and confirm with the author of the avWeek article by contacting him.

http://www.google.com/url?sa=t&rct=j&q= ... 5890,d.eXY

There is absolutely no evidence to confirm any of the RCS mentioned by yourself or to confirm that they are in fact anything other than best case - frontal RCS measures (B-1 etc).

You can have your own set of theories but the fact still remains that no where has there been any mention of this NOT being anything other frontal RCS. Every link that has claimed this, has explicitly stated that this is the frontal best case RCS. Even the old Janes articles form the late 90's to early 2000's mention this (too lazy to look the up now). There has been absolutely no effort by anyone concerned, either with the program or the OEM to actually claim that the best case RCS measurement is anything but that and no one has tried to imply that it is an all aspect RCS for the aircraft.

The number that was released to AvWeek and subsequently to other media sources was the KPP at the time of the competition. They aren't going to be dumb enough to publish extensive RCS modeling and prototype testing results. They have since not said anything to update what was said about the KPP other then that it was bettered and the later claims that the F-35 is stealthier than the F-22A.

That much is known. However, anyone can seek any sort of detailed information about any specification or claim and choose not to believe something until they are given full unrestricted, declassified access to testing. That is fine as long as it is applied to other programs as well. In that way we cannot claim that the B-2 is VLO.

I mentioned less than 0.1 square meter for the F-35 because we really don't know what it is. Yet, you ridiculed the idea stating that we might as well say the F-35 is less than 1 sq m.
See your statement:

brar_w wrote:LOL..I am only going by what has been claimed and published..To be on the safe side, may as well say that the F35's RCS is less then 1 sq m

When you see values that suggest the F-35 and F-22 have a lower RCS than an insect, it raises questions a lot of questions. Namely the methodology as to how testing was done and how it was sold off.

brar_w wrote:There are multiple aircraft, ground based sensors, radar ranges and chambers that measure the entire spectrum of the RF signature. For the F-35 post DR vehicle this has taken over 3 years to actually explicitly document and compare to the KPP. This is why there is a lag in reporting form the time the KPP's were disclosed (again, best case frontal) to the time the senior ACC officials (such as the head himself) claiming that it has not only beaten the KPP's but exceeds the stealthiness of the F-22A.

Stealth technology is as much bout design as it is about finding out the RCS and optimal signatures against various threats. There is an industrial scale effort in the background that manages that.

I was talking about the specification for RCS for advertisement purposes. Typically, much is done in terms of near and far field measurements along with extensive testing prior to IOC.

brar_w wrote:A directorate has existed for over a decade that oversees operations of service owned assets (some open, other secret) and brings in expertise from the academia from time to time to refine the process. Gone are the days when OEM's had exclusive access to their own facilities and expertise and the services relied upon them or contracted them on a case by case basis (as was done during the Have Blue testing).Other RCS facilities have been under government/service control for over 5 decades. .Like everything else the process is always a mixture. Even basic design and refinements are done by the OEM under the management of the larger program manager led team. This doesn't apply just to stealth, RCS etc but also to the basic engineering concerned with the aircraft. Prototype radars are mostly classified but in the past have been custom ordered by the services for their own ranges. Sometimes as in the case of the Lockheed developed VHF radars, it was purchased by lockheed martin after the USAF was done with it so that it could include it in its own company based projects..Other than that, RCS management post testing has been successfully incorporated at the squadron and AEF level since the induction of the F-22. Each aircraft's signature is tracked, monitored and maintained and fed into a database. While relying on a small set of experts was the norm 20 years back, expertise, testing protocols and physical testing hardware has since proliferated to multiple devisions both in the industry and special services run setups.

I'll leave it at that !

As far as it being a model for anyone else - That depends whether anyone else is looking to undertake projects on that scale or not. The stealth infrastructure (and this involves all the testing, evaluating and documenting abilities in addition to the capability to design and produce stealthy designs) exists at the level because there have been investments made since the 70's (in fact earlier) to develop this capability and to maintain a lead over near peer threats with this capability. You can dissect this and write a paper on how to do it better if you please but that would involve access to a lot of things which I seriously doubt exists with anyone outside of the DOD or industry. Btw, there is next to NOTHING known about radar-range modernization and the R&D efforts in the classified budget for complex RCS testing beyond the investments made for the F117 and B-2 systems. One would be naive to think that they haven't ordered custom-prototypes using advanced AESA radars over the last decade when they have spent close to 100 Billion on the USAF classified budget alone in that time frame

The various service directorates have existed for decades that cover all aspects of electromagnetic performance. Of course billions have been spent. More often than not, most of these facilities are operated by various contractors to the program offices, and then another set of contractors to monitor progress. Even places like MIT - Lincoln Laboratories is in the game. It's all about the funding flow, defense contractor corporate and middle class welfare. It is a huge and expensive bureaucratic empire. Most of these fellows in these directorates are technically incompetent and you see all sorts of crazy billing like $230/hour for radar engineering expertise from various contractors. Yes, some of it is absolutely essential to learn the technical lesson once, but repeatedly is ridiculous.

Hobbes · Post by **Hobbes** » 23 Feb 2015 07:34

rohitvats wrote:
Karan M wrote:No reason btw why the IAF shouldnt order another 3 AEWC asap.
Pehle Rafale de do.... (ducks for cover!)