My PAK-FA analysis

[Mahakaya]

Good one. I firmly believe Migs must have a unique and proud soul. All it takes is a pair of sharp eyes and serious effort to resurrect it.

Thanks mate but I feel quite the opposite - if it were the 90s I would still get excited given my age and the times then!

 

[gambit]

Besides its just a prototype - I looked at your last post on FCS - very informative - Thanks for that - but i would still disagree that changes cannot be made - more so to the belly - cos the Photoshop images provided before the plane's release were quite similar to the real thing and they do show a frameless cockpit/canopy and the belly is very much blended showing smooth curves. Will be good to have ur thoughts on it!

Take a look at the conformal fuel tanks on the new F-16. Ever wonder why each tank is shaped that way? External changes should not be made 'willy-nilly', as we Americans say. Depending on the changes, it can have an adverse effect on flight behavior, let alone RCS, as explained below...

Edwards Air Force Base - Media Search

Benefield Anechoic Facility - Wikipedia, the free encyclopedia

Benefield Anechoic Facility (BAF) supports installed systems testing for avionics test programs requiring a large, shielded chamber with radio frequency (RF) absorption capability that simulates free space. This facility is located at the southwest side of the Edwards Air Force Base main base.

The BAF is an ideal ground test facility to investigate and evaluate anomalies associated with EW systems, avionics, tactical missiles and their host platforms. Tactical-sized, single or multiple, or large vehicles can be operated in a controlled electromagnetic (EM) environment with emitters on and sensors stimulated while RF signals are recorded and analyzed. The largest platforms tested at the BAF have been the B-52 and C-17 aircraft. The BAF supports testing of other types of systems such as spacecraft, tanks, satellites, air defense systems, drones and armored vehicles.

Because of the deflection behavior of both audio and EM signals, testing microphones, speakers, antennas and even entire aircrafts to assess their true responses and characteristics to impinging signals is extremely difficult and the results are problematic without full scale anechoic chamber testing. I will focus on EM testing for now, but it is not difficult to imagine the same for audio.

Inside BAF is an antenna transmit a pulse at the F-22, as pictured above, the pulse bounced off the aircraft and at this time three things occur...

The F-22, F-35 and the B-2 uses curves to exploit the 'creeping wave' behavior of EM waves on a curved surface...

Creeping wave - Wikipedia, the free encyclopedia

Creeping waves greatly extend the ground wave propagation of long wavelength (low frequency) radio. They also cause both of a person's ears to hear a sound, rather than only the ear on the side of the head facing the origin of the sound. In radar ranging, the creeping wave return appears to come from behind the target.

There will be a very small portion of the EM signal that bounced off the body and travels back to the receiver, this small echo is called 'specular reflection' and the main part of the signal 'creeps' along the curved body. As this portion of the signal 'creep' along the surface of the F-22's body, minute portions of it will also bounce off the surface as the aircraft is not a sphere. The third significant thing is that these secondary echoes will bounce off the walls of the chamber then bounce off the aircraft again...and again...and again...giving us false RCS value for the aircraft. So what BAF did was to line the walls of the chamber with absorbers, and do not bother asking me the absorbers' bandwidth, so that any 'creeping wave' echoes will be absorbed by the chamber itself, leaving us with only the INITIAL specular reflection -- true RCS.

Next...The aircraft will be tested outside on a 'radar range'...

This is testing the body's RCS when it is exposed to other EM sources, from cosmic background radiation to any stray television signals. Remember...Radar detection was discovered when radio signals were received distorted because of buildings, aircrafts and blimps overhead and even passing ships.

I have said it many times here and I will repeat -- NOTHING is 'invisible' to radar. The US never claimed so. What we claimed is that the body is extremely radar low observable. Radar detection is about finding objects as far away from one's position as possible. So being radar low observable mean by the time the aircraft is detected, it may be too close to one's position. Uncomfortably close if this is a hostile aircraft.

Anyway...Since we do not want to receive cosmic background radiation we filter this type of signal out. We can also filter out echoes from birds, clouds, rain mass, insect swarms, and even man made artifices like buildings. We classify what is filtered out as 'clutter'. The goal of being radar low observable is to have an RCS so low that the aircraft is classified as 'clutter' and you cannot made that determination unless you know how the aircraft will 'echo' first by itself and second when it is exposed to EM signals that you cannot control, such as cosmic background radiation or stray television signals. We can lower the 'clutter' threshold but then our scopes would be filled with so many points, aka 'suspects', that we would not know how to respond to all of them. So once again...The US is not claiming our fighters to be 'invisible', just that they are so low observable that your radars dismiss them as 'junk' or 'clutter'.

So does Russia or India have these testing facilities for the PAK-FA to determine its true RCS? This is why it is not sensible to argue that the PAK-FA's underside can just simply be smoothed out with some surface modifications. The F-117, F-22, F-35 and the B-2 will not have their external surfaces modified by additional antennas or vents or ducts until the modification is fully tested inside and outside of an RF anechoic chamber to see if the proposed modification will raise the aircraft out of the 'clutter' rejection region.

 

[Trichy]

T-50 is a trap for raping indian's money if it is not equipped with plasma stealth device .

ha ha ha

 

[Mahakaya]

Take a look at the conformal fuel tanks on the new F-16. Ever wonder why each tank is shaped that way? External changes should not be made 'willy-nilly', as we Americans say. Depending on the changes, it can have an adverse effect on flight behavior, let alone RCS, as explained below...


Because of the deflection behavior of both audio and EM signals, testing microphones, speakers, antennas and even entire aircrafts to assess their true responses and characteristics to impinging signals is extremely difficult and the results are problematic without full scale anechoic chamber testing. I will focus on EM testing for now, but it is not difficult to imagine the same for audio.

Inside BAF is an antenna transmit a pulse at the F-22, as pictured above, the pulse bounced off the aircraft and at this time three things occur...

The F-22, F-35 and the B-2 uses curves to exploit the 'creeping wave' behavior of EM waves on a curved surface...


There will be a very small portion of the EM signal that bounced off the body and travels back to the receiver, this small echo is called 'specular reflection' and the main part of the signal 'creeps' along the curved body. As this portion of the signal 'creep' along the surface of the F-22's body, minute portions of it will also bounce off the surface as the aircraft is not a sphere. The third significant thing is that these secondary echoes will bounce off the walls of the chamber then bounce off the aircraft again...and again...and again...giving us false RCS value for the aircraft. So what BAF did was to line the walls of the chamber with absorbers, and do not bother asking me the absorbers' bandwidth, so that any 'creeping wave' echoes will be absorbed by the chamber itself, leaving us with only the INITIAL specular reflection -- true RCS.

Next...The aircraft will be tested outside on a 'radar range'...


This is testing the body's RCS when it is exposed to other EM sources, from cosmic background radiation to any stray television signals. Remember...Radar detection was discovered when radio signals were received distorted because of buildings, aircrafts and blimps overhead and even passing ships.

I have said it many times here and I will repeat -- NOTHING is 'invisible' to radar. The US never claimed so. What we claimed is that the body is extremely radar low observable. Radar detection is about finding objects as far away from one's position as possible. So being radar low observable mean by the time the aircraft is detected, it may be too close to one's position. Uncomfortably close if this is a hostile aircraft.

Anyway...Since we do not want to receive cosmic background radiation we filter this type of signal out. We can also filter out echoes from birds, clouds, rain mass, insect swarms, and even man made artifices like buildings. We classify what is filtered out as 'clutter'. The goal of being radar low observable is to have an RCS so low that the aircraft is classified as 'clutter' and you cannot made that determination unless you know how the aircraft will 'echo' first by itself and second when it is exposed to EM signals that you cannot control, such as cosmic background radiation or stray television signals. We can lower the 'clutter' threshold but then our scopes would be filled with so many points, aka 'suspects', that we would not know how to respond to all of them. So once again...The US is not claiming our fighters to be 'invisible', just that they are so low observable that your radars dismiss them as 'junk' or 'clutter'.

So does Russia or India have these testing facilities for the PAK-FA to determine its true RCS? This is why it is not sensible to argue that the PAK-FA's underside can just simply be smoothed out with some surface modifications. The F-117, F-22, F-35 and the B-2 will not have their external surfaces modified by additional antennas or vents or ducts until the modification is fully tested inside and outside of an RF anechoic chamber to see if the proposed modification will raise the aircraft out of the 'clutter' rejection region.

Whoa quite a bit of information there- very very informative - understand ur point - but it also implies that the original was thrown out for the test flights before any such tests had taken place on the aircraft that we saw flying the other day - also since that is the US methodology does not mean there isnt another methodology equally good or bad! BASIC RULE OF SCIENCE AND ASSUMPTIONS!

However, I would agree with the doubt that Russia may not have such facilities, forget India (that I am sure of). But considering the lack of such facilities does not necessarily mean there are no alternative ways of testing!

Anyhow - Thanks a lot for your thoughts! really informative!

 

[albwd]

ha ha ha

Obviously you know nothing about Russians. I do hope you will find more to your "like".

 

[Mahakaya]

Obviously you know nothing about Russians. I do hope you will find more to your "like".

Don't worry buddy we have been trading with them for over 4 decades now so we know probably more than "your like" - anyways u should be happy with the J-11- u certainly did not let them rape you or should I say @ the risk of stating the obvious that you raped em!

 

[gambit]

Whoa quite a bit of information there- very very informative - understand ur point - but it also implies that the original was thrown out for the test flights before any such tests had taken place on the aircraft that we saw flying the other day - also since that is the US methodology does not mean there isnt another methodology equally good or bad! BASIC RULE OF SCIENCE AND ASSUMPTIONS!

However, I would agree with the doubt that Russia may not have such facilities, forget India (that I am sure of). But considering the lack of such facilities does not necessarily mean there are no alternative ways of testing!

Anyhow - Thanks a lot for your thoughts! really informative!

There are alternative ways and one way is to test parts of the aircraft individually in a small RF anechoic chamber then rely upon software to virtually assemble those parts.

Here are a couple visualizations on how a radar sees an object...

The human body is a complex body. Same for an aircraft or a ship. Anything that will allow a surface wave to emit an echo or a specular reflection is called a 'scattering point'. Against a background these scattering points would be in a cluster. Radar detection algorithms would note this cluster and display the cluster as a point of light or a spike on a scope. All you can do is hope that the software that does the virtual assembly is reasonably accurate.

 

[Mahakaya]

There are alternative ways and one way is to test parts of the aircraft individually in a small RF anechoic chamber then rely upon software to virtually assemble those parts.

Here are a couple visualizations on how a radar sees an object...

The human body is a complex body. Same for an aircraft or a ship. Anything that will allow a surface wave to emit an echo or a specular reflection is called a 'scattering point'. Against a background these scattering points would be in a cluster. Radar detection algorithms would note this cluster and display the cluster as a point of light or a spike on a scope. All you can do is hope that the software that does the virtual assembly is reasonably accurate.

Well so we agree on one thing that testing is possible and know that that such tests and various others are conducted throughout the testing phase of the aircrafts from Prototypes till the IoC (IOC - of course not in terms of any changes to the airframe).

Having said that >>>from an initial prototype onwards changes are quite possible and definitely do happen - which was my point by the end of it and that is all we are trying to say from the beginning. IT is only the FIRST PROTOTYPE - CHANGES CAN HAPPEN - However we should leave that upto the PAK-FA engineers to decide if they want to change anything or not!

Also - let me clarify that the Russians have already spent quite a bit on this plane - India has not released the funds right now - $10-12 billion on this can change quite a few things on this JET!!

 

[booo]

@gambit: from what I understood; the LO aircraft have very small RCS (like a bird) and is filtered out by the firmware as clutter. but... the clutter/birds wont be moving as fast as an airplane. so if we give the radar a firmware upgrade to show "fast moving clutter" on the radar, will the stealth of these planes be compromised?

 

[Myth_buster_1]

JF-17 does what is was supposed to do,

Provide Cheap, easy to maintain and advanced Multi role capable Fighter aircraft. At 15 million each , it does that.

Nope. JF-17 and LCA both started with a low cost plane to a mid cost plane as they will eventually evolve as also both air forces requirement have changes specially for Pakistan when IAF will toss 4 and 4.5 generation planes in large numbers.

Its not a make it whatever you want plane. It has it limitations and strong points.

Yes it is like that. thats the whole point of this project.

Making it a stealth aircraft would mean you have to completely change the aircraft. Completely change the plane.

Kindly read my post again. I clearly said "STEALTHY" not "STEALTH"! EF-2000 Rafale are stealthy not STEALTH. JF-17 can achieve some stealthy capability such as a work on nose like F-35 DSI that already it has and RAM coatings. This is just my opinion what i am going to say now.. JF-17 is by no means anywhere close to F-35 in terms of technology but JF-17 has some similarities in design and I am not trying to say JF-17 has a stealth design.
Both planes have a engine layout pretty much the same like one engine and two air intakes on the side not like Flanker or mig-29.

Take a example of PN F-22P which is a future development of type-053H3 and guess what it has stealth characteristics but still its not a stealth frigate but has a reduced RCS compared to type-053.
my point is. PAF may have something like a advance version of JF-17 after 150 orders are completed, it could be a stealthy variant but may not have 5th generation technology and most probably 4.5.

I would like to see PAK-FA like LERX on advance jf-17 variant.

You have spent good majority of the last few days arguing why the PAk-FA is not good.

DONT take my words out of context. I have given PAK-FA credit where it is due. Read the first post of this thread. And i will not just sit and watch indian fan boys run their mouth about how superior PAk-FA is and only comparable to F-22.

Even if you make the airframe stealthy , Get an advanced engine. Reduce IR and RCS and get an AESA radar. You still need to find a way to put an internal weapons bay on the plane.

If PAF "DO" have an intention like this, i am sure they could modify this plane without starting from "scratch" for instance wheels could be removed to the side like in F-35 and weapons bay could take place in the current position of wheels.

 

[Myth_buster_1]

reducing RCS can be achieved a number of ways, Majority of which punch up the price
And cost of Maintenance.

The rest wont give you a reduction enough to even be classified as Stealth. Your sending money reduce RCS, which not effect the planes survivability in anyway, at that point
Well they are better alternatives than the JF-17

Its totally impossible to make JF-17 "STEALTH" like a 5th generation fighter! however "stealthy" characteristic could be achieved to massively reduce current jf-17 RCS without changing the airframe entirely.

 

[Myth_buster_1]

My bad, the time frame should be around 2015. Its not about the service life, but about technology. The entire gamut of things in the MKI has to be upgraded. the technology being used right now is the same that was finalized in 2000.

Their could be "plans" or desire to upgrade 280 or so MKIs in 2015 but it is simply not gonna happen. Just use your common sense. Every equipment in any air force be it USAF completes its self life and then replaced by newer equipments and in some cases that poor equipment is squeezed out for more years out of it. However I do expect if such deal is finalized for advace MKI then we could possibly see them on newly produced MKIs in 2015-2017 depending on production line. The older MKI variants that were inducted hardly hardly a decade ago will first complete its life.

 

[saurabh]

Their could be "plans" or desire to upgrade 280 or so MKIs in 2015 but it is simply not gonna happen. Just use your common sense. Every equipment in any air force be it USAF completes its self life and then replaced by newer equipments and in some cases that poor equipment is squeezed out for more years out of it. However I do expect if such deal is finalized for advace MKI then we could possibly see them on newly produced MKIs in 2015-2017 depending on production line. The older MKI variants that were inducted hardly hardly a decade ago will first complete its life.

I hope you have heard the term MLU - mid life upgrade. Most of the FACs go through this process. It is not just to increase its life, but to enhance its capabilities. Like adding newly developed components. Su30mki is supposed to go through that process at around 2014. When it has finished HALF its life. It will be fitted with, like for eg. new Russian AESA.

 

[sancho]

Their could be "plans" or desire to upgrade 280 or so MKIs in 2015 but it is simply not gonna happen. Just use your common sense. Every equipment in any air force be it USAF completes its self life and then replaced by newer equipments and in some cases that poor equipment is squeezed out for more years out of it. However I do expect if such deal is finalized for advace MKI then we could possibly see them on newly produced MKIs in 2015-2017 depending on production line. The older MKI variants that were inducted hardly hardly a decade ago will first complete its life.

As gogbot tried to make you understand before:

Its an aircraft with a service life of 25-30 years.

MKI was inducted in 2000
2014-15 will be the appropriate time for an upgrade.(MLU)

100+ MKI set to be upgraded.

Common sense would indicate that it is time for Mid life upgrade.

There are negotiation about the upgrade already going on with Russia and Sukhoi:

Sukhoi upgrade on Antony Russia agenda

IN A move that will add even more teeth to its most modern fighter, the Indian Air Force is set to upgrade its fleet of Su-30MKI aircraft in a major modernisation effort that would give it a more powerful radar, newer avionics and better weapons, besides extending service life.
While the fighters are the newest in IAF’s inventory—they were bought in 1996—an upgrade to extend their capabilities will be discussed during Defence Minister A K Antony’s visit to Moscow next week for the ninth meeting of the India-Russia Inter Governmental Commission on Military Technical Cooperation.

“The Russian side has offered an upgrade of the aircraft with incorporation of the latest technologies during the major overhaul and this will come up for discussion,” Defence Ministry spokesperson Sitanshu Kar said.

The IAF is keen to get a more powerful radar for its fighters that will give it an increased detection range as well as the ability to fire longer range weapons. The IAF eventually wants the Su-30MKIs to have an Active Electonically Scanned Array radar, that is also one of the main requirements of the on going fighter trials to purchase 126 fighters.
The IAF is looking for an upgraded avionics package as well as extending the life span of the airframe and engines. Another component of the upgrade will be the installation of the Brahmos cruise missile on the Su-30MKI for land and naval attack missions.

The IAF is also keen on incorporating certain technologies being developed for the Fifth Generation Fighter Aircraft programme onto the Su-30MKI. The FGFA program will be discussed and India will impress on the need to keep with the deadline of inducting the next generation aircraft by 2017.

Sukhoi upgrade on Antony Russia agenda

And in some reports it is mentioned that 2 IAF MKIs are already in Russia for integration of Brahmos and the upgrade.

 

[Kinshuk]

Sir Growler,

Its MLU,

And sukhoi has reached its mid life, I mean by 2014 around it will, So the upgrade is necessary.