stealthflankerI’m still waiting.
stealthflankerI never said the RD-93 wasn’t a 4th Generation Engine! What are you smoking???
Then why bother quoting me there ? What are you trying to do ?
Do you think something off from my estimate ? Which part ? Cooling part ? Empty weight part ? Be clear. Just saying its like KFX or TFX is not clear nor even an intellectual attempt to start discussion.
stealthflankerThe J-31 is very similar to the TF-X or KFX in general concept. Basically an F-35 with two 4th Generation Engines.
and what makes RD-93 not being 4th generation engine ? Are you trying to make your estimates ?
stealthflankerSure it can as the Chinese are doing much of the development of the J-31. In addition it can be produced on a large scale and even exported. As for a total redesign of the Su-57 Russia doesn’t have the time nor the money to do so. Nor, will you find a source that say it is or will…..Yet, knock your socks off if you like.;)
Really. ?. well talking about source.. The only source i found the Russians redesign T-10 into T-10-17 Was Midland’s Famous Russian aircraft books. and That was written like decades after T-10-17 hit the sky.
Plus you haven’t tell yet n how actually J-20 or J-31 can fit into whatever Russian plan or their philosophy in production. How about starting from those first ?
stealthflankerSorry, the issues with the Su-57 can’t be resolved or it would have been redesigned. So, some need to come down to reality and admit it is dead. Other than being used as a “testbed” for a future 6th Generation Design or for Russian Propaganda! (likely both)
Either way it isn’t going to be produced on a large scale. Remember, Russia is the largest country on the planet. So, how many “Stealth Fighters” does it need to protect such a vast country. While, supporting the Russian Army and Navy!
Regardless, it all comes back to Russia no longer has a choice. Unless, it wants to be regarded on the world stage as a minor power…..:eek:
The problem is that None of those can be solved by buying J-31 or J-20. and hell we don’t even know how many would actually be procured and whether redesign would happen. Regarding redesign. It’s not like it’s an Alien concept to Russia anyway as demonstrated on how T-10 becomes T-10-17.
stealthflankerL M bumps = Magical bumbs
Sukhoi bumps = catastroffic bumps with barndoor RCS spikes…This **** never gets old.
Well as long as the bumps still there and it’s located on front. There will still be allegations and stuff.
But it never really touch the real question.. How big it is actually. What’s the magnitude. Or even how often it will be “looked” by radar. Or even, what limitations does it impose to the operation. and how Russian could handle it.
stealthflankerThe most important thing is how big ?. Plus i dont think Russian doesnt aware of it given Su-57 also have a full scale model test here.
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the “IRST bump” is obviously there and it will show up on the instrumentation radar. The best thing is that it will be replaced but for now maybe first batch will have it and accept whatever limitation it impose.
stealthflankerIt just need to be purchased in large amount. say 1000 or more to learning curve effect to take place. Nonetheless given mm Wave seeker of Brimestone. The baseline price will always be expensive. as we have clear trend of working in higher frequency means more precision, more precision means more special machinery required. The parabolic antenna of brimestone, is likely need special manufacture with tight tolerance and let’s not forget multi-mode-multi spectral approach it has. So yeah.
stealthflankerAnd you’re getting your figures for the J-31 where exactly?
That’s my what if estimate. Based on the kind of engine it has.
As seen it has 2 RD-93/WS-13 Which would mean it would be in about MiG-35 or F-18 in weight class. From there one can work out what kind of radar it has. The nose will likely accommodate an AESA with about 60-70 cm in diameter. I took the 60 cm one and then frequency assumption would be 11 GHz which should be reasonable. With that in mind finding the number of modules is the matter of assumption of antenna face filling. i took 90% There the value of 1452 Elements can be found.
Now we only need the cooling capacity of the array. Assuming MiG-35 weight class. It would have about 7.9 kW/sqm of cooling capacity. Finding the possible radiated power per element would then be only require the assumption of possible PAE Which i choose to be 33%. Should be reasonable for Class A Amplifier, (not the most efficient but the most linear with little to no corruption to frequency) The radiated power can then be found to be 6 Watt/ module.
The rest of estimates goes down with Radar Range equation.
stealthflankerThe one for J-31 i meant
The one for J-31 i posted in facebook was early version. the J-31 radar itself was of course 90%. But the other radar is not yet “normalized” to Pd 90%
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As you see only Irbis and APG-83 are normalized.
stealthflankerI think F-35 should have better cooling since it carry more fuel and apparently have bigger cooling vents,
Is your figure with Pd = 90 or Pd = 50?
Which figure ? The recent one i posted was mix. Only those having (R90) is 90%. Rest are taken from open source with no adjustment. Recently however i decided to cut down everything to 90% Detection probability to give a more “standardized” looks.
stealthflankerBut propagation path is changing in very moment, because geography change. How is possible to take a propagation path factor for all enviroments? each enviroment is diferent, so each enviroment have a unique propagaqtion path factor…is it not?
It is. Sea, ground have different electrical properties including the presence of vegetation and this have effects on propagation.
Exact solution however is not available. But approximate and estimates are available, which i am thinking to implement. You can see methods and calculations involved in determining path propagation factor in “Handbook of Computer Simulation, in Radio Engineering, Radar and Communications”
The main weaknesses in the method however is that it assumes uniform distribution of the environment. e.g “jungle all the way” There is no real method yet as far as i know that allows for multiple environment (say 100 km of sea then 10 Km land to radar station).
stealthflankerIIRC, F-35 and J-31 are roughly the same size with F-31 slightly thicker.
do you think their radar performer will be similar
Can’t really say. It’s eventually down to how much they spend on the cooling. Anyone having more excess cooling capacity will have better radar or more “headroom” to get better in the future.
I would say tho the current F-35 will have the processing and power aperture edge as it’s lot more mature and use state of the art module.
stealthflankerNot really an update. but as part of development i added a “result sheet” where one can review its radar specifications, and it has a graphical comparison with some known radars.
The idea is to create a “standarized” sheet one can simply block, copy-paste to paint then put it online or elsewhere to show its Radar.
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Since this calculator is basically for fighter aircraft radar. It is of course at the moment the available comparison “database” would be based on fighter radars too. All values of the comparison database has been “mercilessly” normalized to R90 or Detection range where the probability of target detection is 90%. So don’t freak out on why Irbis-E only have 223 Km of range vs 3m sqm. I assume the 350-400 Km range is 50% detection probability. Same goes for other radars.
In the future i would try working a way that can compare the radar in more “reasonable” value. As its clear that one cannot really compare AEW Radar with Fighter radar nor comparing X-band to VHF band at least directly. The system i am thinking of is to use Frequency as means of comparison. So when you input say X-band the sheet will display X-band Radars and maybe up to C-band. if you input S-Band it will display comparable radar system that works in similar band and so on. If one wish to compare S-band with VHF. Then i need to think a way to make a representative conversion factor for RCS.
As the calculator develops i might also try incorporating some signal processing element, and yes better multipath plus clutter. It will however have weaknesses and may rely on deep approximation and simplification of cases. However it should be good to know if say Pulse doppler is better than MTI in certain situation or vice versa. The main output of the process if i could implement it would be Improvement factor in dB which can later be used along with plot of SCR (Signal to Clutter Ratio) to determine if the processing managed to clear the clutter or not. The range however can no longer be directly computed. It has to be plotted and then range is found through skimming the graph when the signal energy exceeds clutter energy.
The sheet however will first compute free space range, then using that range as the “edge” of the plot and baseline for signal processing calculation.
stealthflankernow im curious if German have its own vision on what’s look alike. Or maybe it’s the one in Airbus Video. The engine would probably “hybrid” between whatever German learns with EJ-2000 and French M-88.
Given the vision of this aircraft. This might entail very sophisticated high bandwidth communication system. The front end would be the AESA radar with suitable waveform for the task. Air datalinking can occupy up to 33% duty cycle at the heaviest point, this might deny the radar to conduct search tho. So more realistic value should be bit lower maybe 10%. The required power would be small, only as high as needed to counter weather. It will have range to at least 200-250 km against typical fighter like Russian one to allow employment of Meteor at very long range if needed. For controlling UAV tho i would expect 3 faced arrays like Russian approach with Su-57. Should there only 1 nose array however that might constrain the employment of high bandwidth datalink but shuldnt be a problem given the UAV will likely always be at front.
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