where is the link??? anyway i think this is not from a valid source.. i'm posting here from Aero India 2009 . its from BR forum posted by prasad..
Huge amount of work has gone on and the pace is absolutely amazing... there is a huge amount of updates from teh last time i saw it in IRSI 07.... amazing pace of work... ppl at CABS are obviously not sleeping.
Anyway, the source for the info I'm putting below are the lecture by CABS Dir and AEW head Dr. Christopher, the person at the Embraer stall, and my 45 minute interrogation (after a CLAP and IFF by the other party) of the AEW project scientist at the stall....
1. Podded vs Conformal Array Antenna:
This argument negates most of Prasun's points, and comes straight from the director:
Conformal antenna:
- Large EMI and loss
- Cooling is required... more power reqts and more size also. Also increases maintenance and failure rate.
- Reduced space in fuselage.
- no windows - increased operator fatigue.
- Maintenance and secrecy - maintenance of the aircraft and overhaul will require removal of the Active Antenna Array Units (AAAU) to maintain secrecy, which becomes extremely difficult for a conformal array.
Additionally, a conformal array would require a huge amount of aerodynamic restructuring and reengineering - not a great idea.
The advantage of course is that the load on the airframe is less and the range does increase some more. However,the conformal nature does remove some amount of fuel that can be placed, so there is indeed a tradeoff.
Podded Antenna:
- Loss and EMI is minimal, which means a far better performance.
- Cooling can also be accomplished extremely easily, with ram-air cooling, which reduces the weight penalty.
- More space in the fuselage for equipment and/or operator cabins.
- More space and windows also means taht the operators are less fatigued and stressed, a major factor in their performance.
- Secrecy is also maintained, since it is much easier to remove the AAAUs.
However, the obvious penalty is in terms of airframe strengthening and load, which necessitates additional control surfaces.
Based on all these aspects, the
IAF decided to use the Emb-145 and the podded antenna. Note that CABS was not the decider here, and only provided the inputs and consultation for the decision.
The TR modules were initially planned to be procured from a foreign nation (no points for guessing who), but they were denied, so DARE (under Dr. Revankar's gp) developed the indigenous 8-TR TRMM for the primary detector and the 4-cell TRMM for the IFF. These have been patented, and are in fact better than the one we originally wanted. So kudos to indian expertise!!
The Antenna is a kevlar composite cladded, and has been tested. Additionally, bird hit tests of the antenna itself have been carried out, and are successful.
As of now, a 2-cell truncated version of the array (the array will finally contain 10 cells) has been fully ground tested for performance, and some truly amazing things have been noted, which I will come to later.
The flight testing of the antenna will be done by Embraer within a year or two, and they will have the full version ready within a few months (6 max). The aircraft will be ready in a year, and Embraer will start integration.
Now, an amazing aspect that hasn't been noted is that this sensor will also have a limited elevation coverage of 10-17 degrees, which i think does not exist on other present day AEW radars. This will allow the radar beam to continue to point in the same direction even if the aircraft goes into a bank or a turn.
Another point that has come out from the truncated antenna tests have been the azimuthal coverage - the nominal value of 60 deg has been exceeded, and they have obtained full performance upto 75 deg, with no loss of range - thus, the array can definitely be pushed up to 300 deg, if not more. Further coverage will result in a loss of range (unspecified - it was mentioned that this will be known with further tests, but also that the exact range or value wasn't open info).
There will be 5 operators with 7 crew rest seats - operator comfort has obviously played a large role in the design.
I suspect that the system may be named "Jatayu", based on the comments made by the session Chair, who invoked that story to talk about our mythology for eye-in-the-sky (after mentioning how the chinese love to say that they were the first at everything, and use their legends to substantiate those claims).... anyway, Jatayu is a beautiful and evocative name, and I do hope they name it so.
Coming to the
info from Embraer
The Platform that has been chosen isn't the R-99A variant (
Embraer R-99 - Wikipedia, the free encyclopedia) of the Emb-145, which is a optimized AEW platform, but the Emb-145 itself. This is apparently because the Indian radar is much bigger and heavier than anything the Brazilians have developed the R-99A for, including their own radar, and due to the larger power requirements.
Thus, the Indian version will be completely optimized, and they will optimize the Emb-145 for our use. This includes the
addition of an extra APU to supply the power needed.
The Person at the Emb stall did mention that our AEW would be far higher performance than their own AEW or anything close, but due to the increased load, will have a larger aerodynamic and range penalty (which he didn't specify since tests are still being conducted) than the normal R99. Since the R99A has the Erieye radar which Pak will get (on a turboprop of course), we can be happy that even our own radar will be far better than anything they have.
The AEW stall at AI:
Extremely interesting info obtained... they are using special, high performance cables to connect the TRMMs to the primary radar antenna. The cables are quite expensive and are imported (and patented). however, i will not add any more due to security considerations, just to be on the safer side.
The truncated radar itself is far more complete than 1 year ago, when it was somewhat like an empty shell with TRMMs placed.
When asked why we didn't go in for a 360 array like on the Israeli G550 AEW, which has a nose and tail radar for 360 coverage, the person mentioned that it was unnecessary, since the radar performance was already nearing that range and coverage, and would only add more weight to an already large platform without much of an advantage... hence, a calculated decision was taken. He pointed out that the nose was not a radome like on combat aircraft but a moulded, metal or composite nose, and would need extensive refitting to add a radar inside, which would add cost, weight and aerodynamic testing as well. Additionally, the threat axes would be covered by the present radar quite effectively, and thus these additions would be unnecessary.
The individual TR modules (8 of which are in a single TRMM) have a power of 65W, but have been overpowered to 75W without problems... this will be valuable for the flight commanders to illuminate Low observable targets. It also points to the amount of adaptability that the radar has built in-to it, which should make us proud.
Additionally, the radar can have different pulse widths (again, I will not specify) to detect and investigate close formations and provide better resolution. more adaptability right there.
The TRMMs and antenna array have been developed by CABS and DARE. LRDE has made the processing units and integration boxes. Additionally, there is a mission data recorder, which records everything - screenshots, radar data, voices, mouse clicks, etc etc etc and stores it for later "post-mortem" and debriefing analysis. This can also be sent to the ground centre by the comm link for real time planning. The bitrates, I wont mention, probably because it is sensitive.
However, when asked about using the radar to communicate, as a directional, high-bitrate data link, he mentioned that it was possible (the americans have achieved datarates of around 248 MBps from their radars) and could be done by the radar, but would be seen as to whether it would really be useful.. However, he was quite enthusiastic in that it could be achieved easily if required.
Inter-operability and data link wouldn't be a problem. The data link would be Israeli, but the format and technique of transfer would be completely indian (ie, until a completely indian data link was developed), and would ensure complete secrecy without any issues. This would be easily achieved.
The model shown this time was also salient in the amount of details as compared to those 1 year ago, which were quite rough... note the satcom comm. systems which form the bulge just behind the cabin doors - something not seen on the older models.
The operability of the AEW will also be at a lower level than the Phalcon.... the Phalcon will work at teh strategic level, while our plane will operate at a sub-theatre level to provide round the clock coverage quite effectively... the operating pattern will be Phalcon-AEW-Phalcon-AEW.... teh phalcons will patrol a large area, while the AEW will provide continuous coverage to plug the gaps and aid the forces in that area.
When asked if we were also looking at a JSTAR type performance, he mentioned that it would not be in this version, but could be in a later update, if the weight permitted. Overall, I got the impression that they have definitely tried to put everything that the Phalcon has into the AEW&C without too much weight penalty, and adding any more large sensors or modes may not be advisable.
However, wrt the ASP project, the AEW project is far far ahead, and is completely different, in that, while the ASP was a simple surveillance platform, and could not any NCW and combat control that the AEW will do. Additionally, the AEW will be a complete system, and is highly effective, even giving a level of accuracy that may be able to guide missiles to aerial targets without the launch aircraft being required to switch on their own radars.....
overall, an extremely potent machine, entirely undeserving of any brickbats that it is getting.