F-35 vs Su-30/35

The F-35 compared with other modern jets.
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ata

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Unread post09 Apr 2015, 15:56

eloise wrote:
AESA can transmit emissions by a proportion of it's total T/R modules number but it will always received reflected signal by all of them, thus the gain always remain the same


this is brilliant...
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Unread post09 Apr 2015, 22:37

hornetfinn wrote:No, what I meant was this:

1. If you fly at 10,000 m altitude and you look down more than 5 degrees from horizon, a target is definitely closer than about 100 km (actually about 114 km at sea level) or it would be below ground which is not good for aircraft.




ha ha ha -- indeed hornfin 'underground' not good for aircraft at all.
There are few flying devices that do well under those conditions, this is one but it can only fly there for a fraction of a second:

GBU-28-Statistics.png
Daddy why do we have to hide? Because we use VI son, and they use windows.
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Unread post10 Apr 2015, 03:27

sergei wrote:That seemed to me that this familiar graph

http://www.ausairpower.net/XIMG/FA-22A- ... 05-APA.png


IT is APA!!!!!

i know they have the tendency to reduce number related to F-35 and pump up number related to F-22 or Russian fighter, but in general the graph is not wrong, because it based on radar equation
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Unread post10 Apr 2015, 03:29

ata wrote:
:doh:

I would send you to the theory how AESA works and how it generates it's directivity pattern. Please, check how AESA gain depends of number of modules. It's not like 2 times less modules - two times less gain :D

go head, post it here and we will discuss it
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Unread post10 Apr 2015, 09:38

Okay...

First of all, to be precise, there can be separate transmit and receive beams especially in AESA radars using technique called digital beamforming. In many situations you can use one wide transmit beam and multiple simultaneous receive beams. My previous example of high elevation/depression angle using multiple beams, I actually meant using one wide transmit beam and several simultaneous receive beams to be used but left that out for simplicity reasons. This technique doesn't affect the receive path gain at all but lowers the transmit path gain depending on how much the transmit beam is broadened (so gain loss is definitely not squared). Also full transmit power can be used in the transmit beam so that’s not affected. This technique is used in many latest AESA radars as it allows much faster volume scanning or much longer dwell time (improves range and sensitivity) or even both. For example using 16 receive beams could search 4 times larger area of the sky AND give 4 times longer dwell times. Max range would still be shorter than using one narrow transmit beam and receive beam, but performance in clutter (for example look down situation against ground) would be better (dwell time is much more important than power there). Of course this method is restricted by the shape of the transmit beam, which is usually some type of ellipse (circular or flat in one axis).

Here is further reading about this method: http://web.mit.edu/jync/www/pdfs/Weberetal-2005.pdf

Another method is using several simultaneous transmit beams along with as many or more receive beams (as in above). This could be achieved using several methods, but in any case only part of the array T/R modules would generate one transmit beam. Basically the whole array would be divided into several small arrays with maybe few hundred modules. This would naturally reduce the gain and power in the transmit beam. However, there are very many radar tasks where maximal gain and power are not needed. Besides, the receive path gain is also not reduced because the whole array is used for receive.

So first method would see only gain decrease (compared to using only one beam for both transmit and receive) within the transmit beam but would be really useful only during volume search. Second one would see both gain and power decrease in all beams, but would be applicable to both searching and tracking. Increasing dwell time would take some of that back at the expense of scan area.

Both of these methods are applicable to any modern AESA radar using digital beamforming. Digital beamforming technology will also allow totally new capabilities for the radar, like extremely fast communications and EW capabilities. These capabilities have already been demonstrated by F-22 and F-35. Such capabilities are not available using PESA or MSA technology.
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Unread post10 Apr 2015, 10:23

eloise wrote:
ata wrote:
:doh:

I would send you to the theory how AESA works and how it generates it's directivity pattern. Please, check how AESA gain depends of number of modules. It's not like 2 times less modules - two times less gain :D

go head, post it here and we will discuss it


Post it here.... :D
First of all, before you started to troll sergei, you had to do the same. That way, how munny calculated max radar range is a point to ask for Nobel prize, but you didn't ask him for confirmation.
Secondly, this question is quite out of topic, isn't it?
Thirdly, because in Soviet Russia everything is for free then there is a link: http://journals.ioffe.ru/jtf/2013/10/p117-121.pdf - this article in Russian (I was not able to find the similar in English) and it describes the very basic single axis array and the way how to calculate it. Even if you don't know Russian, you can see it uses numerical methods (not sure it's a correct translation, but google says it is) or in other words modelling of resulting beam. So, I really didn't check if there is way to calculate approximate directional pattern as a function, but all we did in the past with Ku- and C- band antennas we did in the same way using special soft made by us (actually I believe it should be available some simple examples for MathLab, but I didn't check). It was only more complicated because of two axis.
Conclusion. I would be happy to hear anything about REAL F-35's antenna and how creating several beams could affect it's gain. It would be interesting to make a model for "ideal" F-35-like antenna, and if one day I'll do that, I'll let you know. But anyway, I would not expect gain loss better than 12-15 db for 7 beams. Maybe I'm wrong in numbers so, if any X-band experienced guy could correct me I'll be happy.
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Unread post10 Apr 2015, 10:42

hornetfinn wrote:Okay...

First of all, to be precise, there can be separate transmit and receive beams especially in AESA radars using technique called digital beamforming. In many situations you can use one wide transmit beam and multiple simultaneous receive beams. My previous example of high elevation/depression angle using multiple beams, I actually meant using one wide transmit beam and several simultaneous receive beams to be used but left that out for simplicity reasons. This technique doesn't affect the receive path gain at all but lowers the transmit path gain depending on how much the transmit beam is broadened (so gain loss is definitely not squared). Also full transmit power can be used in the transmit beam so that’s not affected. This technique is used in many latest AESA radars as it allows much faster volume scanning or much longer dwell time (improves range and sensitivity) or even both. For example using 16 receive beams could search 4 times larger area of the sky AND give 4 times longer dwell times. Max range would still be shorter than using one narrow transmit beam and receive beam, but performance in clutter (for example look down situation against ground) would be better (dwell time is much more important than power there). Of course this method is restricted by the shape of the transmit beam, which is usually some type of ellipse (circular or flat in one axis).

Here is further reading about this method: http://web.mit.edu/jync/www/pdfs/Weberetal-2005.pdf

Another method is using several simultaneous transmit beams along with as many or more receive beams (as in above). This could be achieved using several methods, but in any case only part of the array T/R modules would generate one transmit beam. Basically the whole array would be divided into several small arrays with maybe few hundred modules. This would naturally reduce the gain and power in the transmit beam. However, there are very many radar tasks where maximal gain and power are not needed. Besides, the receive path gain is also not reduced because the whole array is used for receive.

So first method would see only gain decrease (compared to using only one beam for both transmit and receive) within the transmit beam but would be really useful only during volume search. Second one would see both gain and power decrease in all beams, but would be applicable to both searching and tracking. Increasing dwell time would take some of that back at the expense of scan area.

Both of these methods are applicable to any modern AESA radar using digital beamforming. Digital beamforming technology will also allow totally new capabilities for the radar, like extremely fast communications and EW capabilities. These capabilities have already been demonstrated by F-22 and F-35. Such capabilities are not available using PESA or MSA technology.


Thanks for the article. I'll check it more precisely, but I got a general idea already. As I said I agree, it's not a point if AESA can create more than one beam. It can, of course. And I said there are several multi-beam radars already existing and used. And your article explains how to form those beams, which is good task itself. Moreover this article is referring to 8m diameter 200 kW S-band antennas which is.... well I believe it should be acceptable parameters even if working in multi-beam mode. Also I didn't understand what do they mean about 220 beams. From picture 6 it seems like they're using more beams to get higher Q value, which is not the same as create several beams to scan independently.
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Unread post10 Apr 2015, 12:45

ata wrote:
eloise wrote:
AESA can transmit emissions by a proportion of it's total T/R modules number but it will always received reflected signal by all of them, thus the gain always remain the same


this is brilliant...


Guys, too much sarcasm, too little discussion. If you put in doubt someone else’s opinion, you’ve got to explain what do you think is wrong with it, otherwise it adds nothing to your point. I know absolutely nothing about this technology, but I’m slowly learning the very basics. Because I have no opinion on my own, I just take in what you guys say, unless someone else clearly disproves it. So far, I have to admit, Sergei and Ata, you have to do better than that, because so far you are getting badly mauled. Dismissing opponents’ arguments and sources as unreliable do nothing for you if you cannot come up with anything more credible.
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Unread post10 Apr 2015, 13:43

shrimpman wrote:
Guys, too much sarcasm, too little discussion. If you put in doubt someone else’s opinion, you’ve got to explain what do you think is wrong with it, otherwise it adds nothing to your point. I know absolutely nothing about this technology, but I’m slowly learning the very basics. Because I have no opinion on my own, I just take in what you guys say, unless someone else clearly disproves it. So far, I have to admit, Sergei and Ata, you have to do better than that, because so far you are getting badly mauled. Dismissing opponents’ arguments and sources as unreliable do nothing for you if you cannot come up with anything more credible.


The problem is that you can only discuss with those who at least understands what is in the discussion topic.
Let start from :
"Assuming the power is being distributed equally across all 7 beams, and taking into account the low gain due to the heavily thinned array, it implies that the maximum detection range for those particular targets is in the 200 nm+ range. Potentially gives the APG-81 similar range to the Irbis-E unjammed and far better range in jamming conditions."
I was very surprised this mode of operation APG-81 in those conditions have been on the video.
The answer to me was the story of how can act AESA radar (which I already knew).
The question was not how it works but why it works that way right now.
Power allocation radar target tracking reduces the overall performance of the radar.
And I tried to get an answer why this is necessary if you have 7 the same type of opponents .
Sane responses were very few and without details.
P/S
In my view, the AESA radar APG-81 can work with these objectives simultaneously without loss of efficiency.
P/P/S While writing the answer to reproach ,I had the assumption in what situation this mode of operation is selected. 8)
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Unread post10 Apr 2015, 16:20

ata wrote:
Post it here.... :D
First of all, before you started to troll sergei, you had to do the same. That way, how munny calculated max radar range is a point to ask for Nobel prize, but you didn't ask him for confirmation.

no, i didn't try to troll anyone, in fact most of what i said until now are either back up by pictures, links or equation
and if you pay attention you will noticed that i didn't think or claim APG-81 have equal or better range than Irbis-e, i didnt ask mummy for confirmation of the way he calculate radar range either simply because i dont think F-35 need a long range radar to be effective, thus for me whether it really match irbis-e range or only match Zaslon-M range is not important
nevertheless i offered my opinion on how it may use seperate beam without reduced gain

ata wrote:Secondly, this question is quite out of topic, isn't it?

no


ata wrote:
Thirdly, because in Soviet Russia everything is for free then there is a link: http://journals.ioffe.ru/jtf/2013/10/p117-121.pdf - this article in Russian (I was not able to find the similar in English) .

ok i will try to put it in Google translate and come back when i understand it
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Unread post10 Apr 2015, 16:29

And Sergei can you posted the flight manual a few page ago here? and explain it?
( i cant see in the link, and cant read Russian either)
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Unread post10 Apr 2015, 17:31

Comparative evaluation of the maneuvering capabilities of the Su-27 tactical fighter F-15, F-16 and Tornado-G2

Objectives 1.
Identify at altitudes and speeds of possible reference dog-fight superiority and loss in our fighter maneuvering properties compared with enemy fighters.
Objectives 2.
Determine the most advantageous range of speeds and altitudes, ensuring full implementation of the maneuvering capabilities comparable aircraft.
Objectives 3.
Construct and analyze field ties and conducting air combat maneuvering.


Table Su-27 vs F-16A where + denotes advantage of the Su-27 and - the advantage of F-16a
The first column indicates the comparison criteria and range of heights and speed
The second column compares short energetic maneuvering
The 3 column compares to long-term steady maneuvering
The 4 column compares for acceleration and energy rate of climb
Attachments
Su-27vsF16.png
F16A.png
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Unread post10 Apr 2015, 18:55

So far, I have to admit, Sergei and Ata, you have to do better than that, because so far you are getting badly mauled. Dismissing opponents’ arguments and sources as unreliable do nothing for you if you cannot come up with anything more credible.


Ok, about "badly mauled" I want to say.
The tactical advantage of F-35 is based on three points: 1. Stealth tech 2. Sensors (both radar and optical) 3. Ability to work in a group with many different units. I have my 1 penny about each of them.
1. I've seen here several numbers about it's RCS, but no good information at all. What I mean "good information" - is very simple. It would be perfect to get 3D map of plane's RCS (which is obviously impossible) but at least I'd like to get it's MAX value, not only lowest possible number. For example F-35 has no protection or any shielding of it's engine, so from the back at least engine must be absolutely visible. I've seen here the picture where even F-22 with shielded engines has 20dB (!!!) higher RCS than in front direction. Only turbine blades should give us about 1 sq.m. It's absolutely clear that from the top or from the bottom it's RCS must be much higher than from the front direction. I've heard here about 0.001 sq.m. value. Ok, but what were the conditions of measurements? I've seen many graphs, is it modelling? If not, if those graphs based on measurements, then what is standard deviation? That's why I said "too many commercial" (by the way, I've found later sources of almost all the statements from this topic" and it's Lockheed and associated) and asked for more or less practical examples. I guess, F-35 is not that stealthy as Lockheed wants everybody to think. They maybe not lie, but they only sell the best numbers, and hide what is not that good.
2. Radar. Well, it's great radar, no doubts. I have just few words about LPI. Again, only one article here with simple technology explanation. Anyway, Lockheed statements only describe the distance of detection of enemy plane. And they declared that LPI "decrease probability to detect LPI source". But what about RANGE of that detection? In other words, what about range where Flanker will be able to detect LPI source? It's important, because signal received from the target (F-35 -> target -> back to F-35) is much-much lower than detected at target side (F-35 -> target). Yes, LPI decreases detection range (normal radar is like huge torch in the sky, while LPI is like normal lamp) but if it's like "detectable from 200 km", it would not help.
Optical sensors. Did you guys find somewhere what is the resolution of sensors? I've calculated and to resolve 5 meters diameter object at 50 km (object will take only 1 pixel, so, no recognition, no speed detection and it's absolutely ideal situation) it will require 15000x15000 sensor resolution to cover 90 degree (which is stated at Lockheed description). Well... it's possible of course, but it doesn't seem possible if we remember it's 10 years old sensor. And even today, this level of sensors are installed on satellites used for Google maps.
Moreover, I've never find those two statements used together - "system covers 360 degrees area" and "system is able to detect XX size object at YY distance". What I think, is that optical sensors have relatively low resolution which is only enough to create augmented reality for pilot, watch for ground targets, etc... And to "detect Flanker-size object at bla-bla-bla distance" it's using ZOOM. But zoom means "no 90 degrees of detection area", but the same kind of thing as Flanker and almost any modern jet in the world already have.
3. Working in group is not something unique. And gives the best result if every unit of group has it's own skill. I've seen Lockheed promo where F-35 is used to guide Hercules-based drone full of anti-radar missiles... I have no idea how they sell this science fiction to someone who pay the money, but F-35 (based on what I've said earlier has no special skill), it's a plane quite stealthy, quite fast, quite good. But it's not perfect in every of that.
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Unread post10 Apr 2015, 21:41

ata wrote:1. I've seen here several numbers about it's RCS, but no good information at all. What I mean "good information" - is very simple. It would be perfect to get 3D map of plane's RCS (which is obviously impossible) but at least I'd like to get it's MAX value, not only lowest possible number. For example F-35 has no protection or any shielding of it's engine, so from the back at least engine must be absolutely visible. I've seen here the picture where even F-22 with shielded engines has 20dB (!!!) higher RCS than in front direction. Only turbine blades should give us about 1 sq.m. It's absolutely clear that from the top or from the bottom it's RCS must be much higher than from the front direction. I've heard here about 0.001 sq.m. value. Ok, but what were the conditions of measurements? I've seen many graphs, is it modelling? If not, if those graphs based on measurements, then what is standard deviation? That's why I said "too many commercial" (by the way, I've found later sources of almost all the statements from this topic" and it's Lockheed and associated) and asked for more or less practical examples. I guess, F-35 is not that stealthy as Lockheed wants everybody to think. They maybe not lie, but they only sell the best numbers, and hide what is not that good.

the F-135 engine will only be visible if you managed to get directly behind the F-35 ( that is not very possible )
RCS from the top or bottom of F-35 will obviously higher than from front , however it not relevant because the only time you see F-35 directly from the top or bottom is in close range dogfight,
most other time your radar will look at F-35 frontal angle
about the pictures i posted, these are graph of F-22, YF-23 RCS scattering simulation if they was made purely from metal ( based on 3D model of the aircraft )
Image
other graph for RAM showed that RAM will reduce RCS by another 20-30 dBsm
Image.
Image
thus i make the conclusion that with shaping + RAM it not very hard to achieved frontal RCS around - 30dBsm to - 40dBsm in X band
if the simulation are acceptable accurate the value of 0.001 m2 for F-35 is achieved with angle of around 45 degree each side frontal
btw, most statement in this thread are not from LM



ata wrote:2. Radar. Well, it's great radar, no doubts. I have just few words about LPI. Again, only one article here with simple technology explanation. Anyway, Lockheed statements only describe the distance of detection of enemy plane. And they declared that LPI "decrease probability to detect LPI source". But what about RANGE of that detection? In other words, what about range where Flanker will be able to detect LPI source? It's important, because signal received from the target (F-35 -> target -> back to F-35) is much-much lower than detected at target side (F-35 -> target). Yes, LPI decreases detection range (normal radar is like huge torch in the sky, while LPI is like normal lamp) but if it's like "detectable from 200 km", it would not help
.
i already explained to you that LPI is achieved because enemy's RWR classifying AESA radar signal not as a radar signal but as background clutter ( not necessary because the signal is weak, but because they spread for a wide frequency and and dont have particular pattern)
and as explained before RWR can't generate fire solution again moving air target, thus even if the RWR on Su-35 detect and recognised APG-81, it still wont allow you to attack the F-35
ata wrote:Optical sensors. Did you guys find somewhere what is the resolution of sensors? I've calculated and to resolve 5 meters diameter object at 50 km (object will take only 1 pixel, so, no recognition, no speed detection and it's absolutely ideal situation) it will require 15000x15000 sensor resolution to cover 90 degree (which is stated at Lockheed description). Well... it's possible of course, but it doesn't seem possible if we remember it's 10 years old sensor. And even today, this level of sensors are installed on satellites used for Google maps.
Moreover, I've never find those two statements used together - "system covers 360 degrees area" and "system is able to detect XX size object at YY distance". What I think, is that optical sensors have relatively low resolution which is only enough to create augmented reality for pilot, watch for ground targets, etc... And to "detect Flanker-size object at bla-bla-bla distance" it's using ZOOM. But zoom means "no 90 degrees of detection area", but the same kind of thing as Flanker and almost any modern jet in the world already

F-35 have 2 optical sensor :
EOTS for long range = narrow Fov
DAS for short range = 360 degree Fov
F-35 likely use Apg-81 to detect Su-30/35

P/s: you have to stop with you double standards Ata, anything good related to F-35 and you instantly said it just advertising, anything good related to Su-30 and you instantly accepted it as the truth, that isnot a healthy attitude for arguing
Last edited by eloise on 10 Apr 2015, 22:00, edited 1 time in total.
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Unread post10 Apr 2015, 21:54

sergei wrote:Comparative evaluation of the maneuvering capabilities of the Su-27 tactical fighter F-15, F-16 and Tornado-G2

Objectives 1.
Identify at altitudes and speeds of possible reference dog-fight superiority and loss in our fighter maneuvering properties compared with enemy fighters.
Objectives 2.
Determine the most advantageous range of speeds and altitudes, ensuring full implementation of the maneuvering capabilities comparable aircraft.
Objectives 3.
Construct and analyze field ties and conducting air combat maneuvering.


Table Su-27 vs F-16A where + denotes advantage of the Su-27 and - the advantage of F-16a
The first column indicates the comparison criteria and range of heights and speed
The second column compares short energetic maneuvering
The 3 column compares to long-term steady maneuvering
The 4 column compares for acceleration and energy rate of climb

thanks , i will have a look at it
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