PAK FA, T-50: News #1

TR1 wrote:Well, it is disturbing that the Greek planes were not able to lock on to THIS:

http://farm2.static.flickr.com/1320/5153694464_61b5943315.jpg

http://farm2.static.flickr.com/1164/5143854162_b2a2304d2a.jpg

To put lightly I am more than skeptical over F-22 supposed IR coverage. Square nozzles and fancy materials don't magically make the signature go away.

I doubt the origins of this photo. and the second one looks like a missile not a plane.

anyway, where is this image from?

Google. You can look around and find plenty of photos of F-22 being looked at through various IR gear. For example, civilian IR gear at airshows. If they get such an image, one wonders what modern IRST sees. And no, there is no "airshow" IR mode.

TR1 wrote:Google. You can look around and find plenty of photos of F-22 being looked at through various IR gear. For example, civilian IR gear at airshows. If they get such an image, one wonders what modern IRST sees. And no, there is no "airshow" IR mode.

No need to be cynical.

two things.

First in airshows the plane is very close. IR diminishes with range, and second, it may not be in "weapons" rated spectrum. i.e. missile seekers may not work in that frequency.

I'll look into it. But something is too good to be true here.

You can't separate the 800km/h fly from the other flies. The reason? you have to process in the CPU all the flies that the radar picked up and find the one that travels at 800km/h. Want to guess how many flies the radar would pick at a range of 60 miles ? It would make the process so slow it is useless.

Sorry, but you are wrong.

A moving object that is hit by a radio wave (ie radar beam) distorts that beam by creating a doppler shift in the wave that can be used to determine the speed and direction of the target in relation to the radar.

Most look down radars use doppler shift to ignore all objects that are not moving on the ground. It also ignores objects moving less than about 120km/h so that it doesn't pick up cars on the motorway.

The doppler shift on the return signal can be used for clutter rejection so the signal with no doppler shift is moving away from the aircraft at the same speed the aircraft is flying. Objects returning a doppler shift equivalent to the flight speed of the aircraft with the radar or 120km/h in either direction towards or away from the aircraft can be eliminated from the display and will not be processed at all. That leaves targets moving fast enough to be missiles or aircraft.

To search for a target with the RCS of a fly you need a lot of power and a large antenna and set your clutter rejection to 100km/h. There are no real insects that can fly at 100km/h so anything you detect will be a stealth aircraft. The only problem is the small reflective surface means you need a powerful signal and a large antenna to collect the target information.

The best solution is long wave radar that is not effected by the stealth aircraft shape that does not see an F-35 as an insect size target. In IR frequencies as well as in visible light frequencies the F-35 is an F-35 sized target...

IRST is fantastic, it doesn't give you tracking vectors though.

The angular tracking information from an IRST is much better than radar. What it doesn't give is range, but with such a precise angular tracking capability it means your can steer your radar antenna directly at the target and give it a 20kW ping to get range info, or you can get precise angular info and with a wingman 100m or 1km beside you use his angular info in real time to triangulate range.

What I mean is that even when the IRST targets a heatsource, it doesn't know the target's vector which means it cannot provide a targeting solution to the missile, i.e. the missile may fly the wrong path to the target while the target is turning or moving away such as the missile shot is useless. A radar would tell you this because it knows the target is flying away and it can calculate the range, the IRST cannot.

Only Active radar homing missiles need range information, because they need to know when to turn on their seekers to guide for the terminal phase of the intercept.

An IR guided missile does not need range information... it just needs to see the target, and if you are tracking them with IRST then it is likely the target is within range of the R-27ET.

The missile wont know the distance to the target, but it will fly towards the target. It will fly straight so the target will appear to move in its field of view if it is heading left or right or up or down so a modern missile will detect this movement and then manouver to fly ahead of where the target is moving... ie where the aircraft is moving to rather than where the aircraft is at the moment. This means that the missile will by flying an intercept course rather than a tail chase course and will be much harder to evade.

Further more I mentioned in a previous post that the IRIS-T missile on the greek F-16s with JHMQS could not get a lock on the rear end of an F-22. Now that is impressive and disturbing at the same time.

Disturbing that an ancient F-16 could get on the tail of an F-22 and could have shot it with its cannon, but instead wasted time trying to get missile lock?

Sounds like the IR seeker of IRS-T is rubbish to me. Modern IR sensors in AAMs don't require an intense heat source to get a lock...

Of course there are many innovations like letting part of a cold air from the inlet of a engine flow around engine reducing its temperature and at the end mixing it with hot exhaust but rally that does little to effect modern day IC systems.

As you picture shows TR1, not much is gain on heat field with its flat nozzles. I bet more contributions is by blocking radar waves bounce from certain angles.

The flat nozzles are about radar waves and a slight increase in mixing cold air with hot.

The point is that any turbofan engine has hot air and cold bypass air going through it.

Modern IR sensors can detect cold objects as well as hot objects and are not designed to chase the hottest thing they can see.

BTW those photos of the F-22 were clearly taken during takeoff when the aircraft is in full AB.

First, the Greek F-16s are not ancient, they are blk 52+ with JHMQS and integrated combat suite.

Second, the IRIS-T is one of the best missiles around. It was superior to all versions of the aim-9 before the X.

Second, still on the fly, I don't agree. RADARs operate on the principal of rejecting a vast amount of returns essentially everything with a very small trace. The reason is that in a typical cone, with a range of say 100Km the radar will pick up an enormous amount of returns.
The radars do not identify targets based on dopler effect, they identify targets based on return signal strength. That means that first the processor identifies a large RCS (i.e. mountain) and then it decides if it is a mountain by checking its doppler effect.

If the reverse is to be true the processing power of the radar to identify and then buffer and then classify/ track a fly sized object is mind boggling.

RADARs operate on the principal of rejecting a vast amount of returns essentially everything with a very small trace. The reason is that in a typical cone, with a range of say 100Km the radar will pick up an enormous amount of returns.
The radars do not identify targets based on dopler effect, they identify targets based on return signal strength. That means that first the processor identifies a large RCS (i.e. mountain) and then it decides if it is a mountain by checking its doppler effect.

If the reverse is to be true the processing power of the radar to identify and then buffer and then classify/ track a fly sized object is mind boggling.

A radar directed downwards will get most of its signal returned by the ground and everything on the ground.
That is the problem with downward looking radar.
Some types of radar need to be able to see the ground so they stitch the return signal together to make a lattice of the ground.
Terrain avoidance radars for instance would be pretty useless if they ignored the ground as clutter.
A weather radar on the other hand is interested in moisture in the air and has no interest in looking down at the ground.
The AESA radar of a Mig-35 scanning for ground targets on the other hand wants to see specific things on the ground... flat metal surfaces, moving objects etc etc.

The obvious problem is clutter rejection. For a terrain avoidance radar the ground is not clutter, so returns with a doppler shift equivalent to the speed of the aircraft the radar is mounted on is not rejected, but the terrain at the level of the aircraft and above is the real interest of the system so it doesn't have to process all returns.

A look down radar scanning for flying targets or threats like enemy fighter aircraft, or enemy cruise missiles will not see such small targets if it doesn't do something about the radar returns from the ground.

Originally... without modern processing power, they simply used the doppler effect of a moving object on the radar signal, so everything that is moving above a threshold speed is captured and processed and displayed on a screen.

In fact the US military things the North Koreans plan to use An-2 transports to drop paratroopers in South Korea and will use the An-2s very low speed capability to be stealthy as a pulse doppler look down radar would remove an An-2 flying at 60km/h as clutter and it wouldn't appear on a fighters look down view. If they changed the clutter rejection settings then they would start seeing cars on motorways and birds appear on their radar screens.

With modern processing the radar return can be recorded or used as a snapshot and can be compared with earlier or later records or snapshots and anything moving can become the centre of attention. They use the same method to find new asteroids.

The point is that to actually use its supercruising performance an F-22 and for that matter an F-35 will not be flying low where even trash fire can hit them and ruin their stealth, they will be flying high where no other birds or insects are.

I am not for a moment suggesting detecting stealth aircraft is trivial and easy, but it is hardly impossible either.

BTW regarding your comments about heat not being visible from long distances... heat is heat, so if the IRST of the Mig-35 can detect an aircraft at 50km then that means any aircraft... stealthy or not.

The Russians are developing all new missiles for the PAK FA, which will likely include IIR guided missiles.

IIR guided missiles don't just see hotspots, they form an image of the target like a thermal imager. Such a missile will have a thermal signature library in an onboard database so it could be fired at a group of enemy aircraft and select its own target based on target priority.

Very much like the Brimstone missile except it uses MMW radar as an active sensor.

If the reverse is to be true the processing power of the radar to identify and then buffer and then classify/ track a fly sized object is mind boggling.

As I said, using doppler shift the computers in the radar system only process the data that gets to them. Things (radars can't distinguish mountains from the ground BTW) that are moving in relation to the general background noise get processed.

In a ground attack radar then signals from large flat metal surfaces or moving targets will stand out, but for searching for air targets a radar will not be interested in object return signal strength because they know there are aircraft and cruise missiles will small RCS.

Radars are man made and are optimised for the threats the designers anticipate.

In the past radars might reject return signals that are weak because the opponents haven't had stealth aircraft so there is no need for it.

Really, if your fear is Turkish F-35s then I think your best bet will be a combination of S-400 and a stealth cruise missile of your own to take out F-35 airbases.

Spending an enormous amount of money on PAK FAs... well no disrespect, but do you think the US would sell F-35s to Russia or Belarus?

Despite good relations with Greece, you are still part of NATO which is a military organisation.

GarryB wrote:A moving object that is hit by a radio wave (ie radar beam) distorts that beam by creating a doppler shift in the wave that can be used to determine the speed and direction of the target in relation to the radar.

Most look down radars use doppler shift to ignore all objects that are not moving on the ground. It also ignores objects moving less than about 120km/h so that it doesn't pick up cars on the motorway.

The doppler shift on the return signal can be used for clutter rejection so the signal with no doppler shift is moving away from the aircraft at the same speed the aircraft is flying. Objects returning a doppler shift equivalent to the flight speed of the aircraft with the radar or 120km/h in either direction towards or away from the aircraft can be eliminated from the display and will not be processed at all. That leaves targets moving fast enough to be missiles or aircraft.

Not bad, but a bit of an oversimplification of everything that goes on. I may come back and expound on some things a bit later on. For one thing, doppler notch is a significant problem with any doppler processing system, although it's usually far more irritating to fixed emitters like SAM radars.

If anyone wants to get smart on radar theory, here's two superb reference sources:

Introduction to Airborne Radar, by George Stimson: explains all of the basics behind radar workings and signal processing and examines everything from an airborne perspective. Here's a link to the table of contents, index, and a sample chapter: http://www.scitechpub.com/Explore/9781891121012_Stimson.pdf

Introduction to RF Stealth, by David Lynch Jr: way more technical, way more math-oriented, but explains a great deal about LO design. Goes into LPI radar design and performance in significant depth as well.

GarryB wrote:To search for a target with the RCS of a fly you need a lot of power and a large antenna and set your clutter rejection to 100km/h. There are no real insects that can fly at 100km/h so anything you detect will be a stealth aircraft. The only problem is the small reflective surface means you need a powerful signal and a large antenna to collect the target information.

The best solution is long wave radar that is not effected by the stealth aircraft shape that does not see an F-35 as an insect size target. In IR frequencies as well as in visible light frequencies the F-35 is an F-35 sized target...

To find an LO target you need, typically, an assload of power and a smaller wavelength. Power is really the key here, because if you aren't going to get a lot of energy reflected back to the emitter, you need to make sure what comes back will be interpretable at a militarily useful range. Large wavelengths ignore traditional FCS-band LO treatments like serrated edges, but there are ways to defeat those as well.

GarryB wrote:The flat nozzles are about radar waves and a slight increase in mixing cold air with hot.

The 2D nozzles were a combination of rear-hemisphere LO considerations, and the originally proposed inclusion of thrust reversing capability for short-field performance.

Not bad, but a bit of an oversimplification of everything that goes on.

Of course it is my friend. This is not RADAR101, and I only know this stuff at a fairly superficial level anyway, but I know enough for a very basic understanding.

And to be sure the people at Sukhoi and Mig know this stuff a lot better than any of us.

To find an LO target you need, typically, an assload of power and a smaller wavelength. Power is really the key here, because if you aren't going to get a lot of energy reflected back to the emitter, you need to make sure what comes back will be interpretable at a militarily useful range. Large wavelengths ignore traditional FCS-band LO treatments like serrated edges, but there are ways to defeat those as well.

You sure you meant smaller wavelength if longer wavelengths defeat shaping like serrated edges and thin coatings of RAM?

I agree that when you get to very short wavelengths like visible light the F-22 is F-22 sized and not really stealthy at all.

GarryB wrote:You sure you meant smaller wavelength if longer wavelengths defeat shaping like serrated edges and thin coatings of RAM?

I'll expound on this tomorrow or Saturday.

You are talking to a New Zealander... tomorrow IS Saturday...

...and I am sitting sweating in shorts and a t-shirt in the middle of summer!

Infrared image video of F-22 flying at Farnborough air show.

Air International April 2012

PAK-FA Update

http://www.mediafire.com/?k4lkyuyv9p7tmnk

Austin wrote:Air International April 2012

PAK-FA Update

http://www.mediafire.com/?k4lkyuyv9p7tmnk

Excellent find.

So we have first problems appear on PAK-FA

1. Structural cracks T-50-1 and vertical stabilizer cracks T-50-1/2/3

2. T-50-3 equipped with AESA N036, RWR, electrooptical jammer ??, IRST, decoys.

3. Izdeliye 30 will have 18 ton of trust in afterburner mode and 11.5 ton in dry mode - MASSIVE.

4. Izdeliye 30 - first production 2016.

EO Jammer = DIRCMs... basically a laser dazzler to block optical and IR seekers.

It is better to find cracks and structural problems now than later because there is time to fix them.

It is important to note these aircraft are likely made of new materials so they will be learning a lot from this experience.

... and imagine fitting these new engines to a bog standard Su-27... 11.5 ton thrust in dry mode should mean near full AB performance without AB...

I rather doubt the airframe will handle higher flight speeds, but extra thrust will certainly greatly improve acceleration and weapon load.

Also keep in mind that the PAK FA will be a smaller aircraft than an Su-27.


Thanks for posting Austin.

Someone to explain us the differences between the role of Su-35 and PAK-FA in Russian air force?

George1 wrote:Someone to explain us the differences between the role of Su-35 and PAK-FA in Russian air force?

PAK-FA is not even in serial production, let's not get ahead ourselves with roles.
But both are primarily air superiority aircraft.

The Su-35 was seen as a stopgap aircraft that could fill the roles a 5th gen stealth fighter was not needed for.

It could also be used to introduce many of the technologies being developed for the PAK FA and increase aircraft numbers with commonality of systems so more parts were produced to introduce economies of scale to reduce costs of purchase and maintainence.

Another feature of the Su-35 is that it will become the export option for countries they are not prepared to sell the PAK FA to.

How does Su-35 stack up against the F-35. If it is near by even 80% then a wise third world nation like Indonesia, Malaysia or Egypt should go for Su-35s for roughly 60M odd vrs $100M for F35s. If Plasma stealth is further tuned by the Russians, then Su-35 can be a world beater in its class.

victor7 wrote:How does Su-35 stack up against the F-35. If it is near by even 80% then a wise third world nation like Indonesia, Malaysia or Egypt should go for Su-35s for roughly 60M odd vrs $100M for F35s. If Plasma stealth is further tuned by the Russians, then Su-35 can be a world beater in its class.

No offense, but asking how much, percentage wise, a plane stacks up against another plane is pretty ridiculous, and won't get a serious answer.

No serious plans for plasma stealth on the Su-35 in any case.

The primary feature of the F-35 is stealth.

All that sensor fusion stuff... the Su-35 will have the same.

The question comes down to what level of stealth will the F-35 in the export model.

The Su-35 has flight range, speed, payload options, and price advantages over the F-35, but at the end of the day a country like the UK or Australia would never even consider seriously buying an Su-35.

For Indonesia and indeed in BRICS countries there is certainly going to be a lot of interest in later model Flankers... India has Su-30MKI and FFGA, China is interested but needs to decide whether it can meet Russias conditions not to copy and proliferate... South Africa is a possibility I guess though not a traditional direct Russian client, and Brazil might want the political ties that are created by buying US gear more than it wants a useful plane... lets face it... Brazil and South Africa really don't need expensive fighters.

Saudi, UAE, Israel and Turkey are going to load up on F35s. This makes Syria, Iran and Iraq natural clients for Su-35s.

Su-35s can also have potential in countries like Argentina which has tensions with UK and it was mentioned recently that 4 EFTs stationed at Falkland Islands can single handily take out major chunks of obsolete Argentine Air Force.

It would be stupid for Brazil to buy anything else than Su-35s. Such actions are not good for calling something an alliance like BRICS. On paper stuff needs to be put into real world actions also.

First of all BRICS is an economic grouping and fairly loose at that.

Second need does not equate with what you actually get.

Russia doesn't just sell anything to anyone and I rather doubt they will want to risk selling to Iraq.

With the economic sanctions on Iran they probably couldn't afford to buy Su-35s and considering all the time they have had to buy Russian gear and have not bothered I don't see that changing any time soon.

Iran bought some Su-24s and really only bought Mig-29s to make up numbers with those that escaped from Iraq to get support contracts for all their Migs.

Now if the Iranians put in an order for 200 Su-30s or Su-35s to replace their F-14s then the Russians might be interested.

I rather doubt Argentina can afford a military powerful enough to take on the UK again, though certainly 100 Su-35s with 200km range RVV-BD missiles plus RVV-SD and RVV-MD missiles would make them very very capable opponents for the British... at the end of the day the Argentinians have little in terms of a Navy to counter the British SSNs which would make sea based support of an invasion or occupation force costly.

Ironically the Lada class sub was designed specifically for short range hunting of enemy SSNs and it has a powerful armament and sonar suite... half a dozen of them would really test the British navy.

The problem is that the cost for Argentina would outweigh the benefits and their economy would collapse under the weight of such military purchases.

GarryB wrote:South Africa is a possibility I guess

I wouldn't necessarily agree, given that they just recently spent the money to replace the Cheetah fleet with Gripens. Gripen might not have huge legs but it certainly suffices for the air defense role in the area. Not that the Su-35 wouldn't be able to do the job as good or better, but I think the chances of a South African buy have came and went. Now, if you want to talk 15 years from now, and if Russia ever gets a single-engine JSF equivalent flying about, then they might be a good potential buyer if they can be convinced that they have a requirement for LO.

I agree with most of what you are saying, which is why I said SA is only a possibility.

I think however if they can start to sort out some of their problems like unemployment and crime that they have huge potential to grow and I would expect rather than buying off the shelf they might try something a bit more ambitious and try a joint development project.

A single seat light fighter program that includes a range of countries led perhaps by Mig has some potential as long as it does not get too expensive.

Of course if they leave it too long then an UCAV might be a better program.

What type of missiles/guided bombs can be carried in PAK-FA internal weapons bay?