Maury Markowitz
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I must have missed it earlier in the thread - what is the hexagonal object on the bottom in front of the weapon bay?
Sukhoi T-75 LTS (CheckMate)
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AleDucat
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Well, guessing by the fact there are no laser turrets on the top and bottom like there are on the Su-57, I guess they mean they could add more to the system? There are many laser defense systems in Russian service, they were one of the first if not the first early adopter of them IIRC, but the Su-57's laser turrets are unique as they also have imaging functions as well apparently.
Judging by phrasing, it's probable that they would add laser defense functionality onto the system, as for landing, no idea, something similar perhaps to how the Su-57 has one of it's short range missile bays equipped with a forward looking thermal imager, apparently for landing and low level flight. Though I think it also provides general observation as well, as Su-57 lacks the imaging sensor next to the OLS compared to the Su-35.
In all honesty it's kind of a strange setup in general for Su-57 and the LTS, especially compared to the conventional and straightforward Su-35 setup when you look at documentation for the systems in general.
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I think you probably need to see the original Russian to get a sense of the intent, maybe just that you can add extra sensors for FLIR/situational awareness, not just targetting. ROSTEC need to get a better translator/English speaker for their tweets, it's not the first time I've noticed mangled English and they're doing themselves no favours.
The Ministry of Defense may consider the purchase of Checkmate fighters under the GPV
Deputy Prime Minister Yuri Borisov pointed out that foreign customers are always interested in whether the native armed forces take the equipment they offer for export.
tass.ru
Deputy Prime Minister Yuri Borisov pointed out that foreign customers are always interested in whether the native armed forces take the equipment they offer for export.
Минобороны может рассмотреть вопрос закупки истребителей Checkmate в рамках ГПВ
Вице-премьер Юрий Борисов указал, что иностранные заказчики всегда интересуются, берут ли родные вооруженные силы ту технику, которую предлагают на экспорт
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The Ministry of Defense may consider the purchase of Checkmate fighters under the GPV
Deputy Prime Minister Yuri Borisov pointed out that foreign customers are always interested in whether the native armed forces take the equipment they offer for export.
Минобороны может рассмотреть вопрос закупки истребителей Checkmate в рамках ГПВ
Вице-премьер Юрий Борисов указал, что иностранные заказчики всегда интересуются, берут ли родные вооруженные силы ту технику, которую предлагают на экспорт
This is a good path. as yes someone like say..Indonesia always interested in stuff being mass produced or in the owner country's standard. the only exception is Su-27SKM.
buying goods already proven tried and true in the origin country is kind of good scheme that most if not all of the bugs are worked out and a steady stream of parts, experienced training are available.
LMFS
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As usually, the government does not want to paint the military into a corner with regards of the LTS, but it is clear from the beginning that the plane has been designed with the VKS in mind and in agreement with them. Such an effort as developing a new fighter and not taking advantage of it in the interests of the country's defence, that simply makes no sense.
Do we have an RCS estimate for the Su-75? When I saw it, I was immediately thinking the Russians were aiming for a fighter capable of killing the F-35 in a stealth vs stealth fight. While the inlet design is quite disappointing, it still has the tail configuration of a YF-23. On paper, the Su-75, barring the issue with the inlet, is purer stealth than the J-20, the Su-57, and even both the F-22 and F-35.
How is it "purer stealth" than the J-20? If anything, the J-20 looks stealthier than anything Russia has ever created. Comparing it to the American planes are even more pointless.
No tail elevator. Just a V-tail, like with the YF-23, which was known to be stealthier than the YF-22.
If you're pointing at the weird inlets in the back, you have similar bay / engine cooling inlets on the underside of the F-35's wings.
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It makes sense for the Russians, have a low-stealth multi-role heavy fighter in the Su-57, complement it with a high stealth lightweight fighter like the Su-75. The Su-57 does the dogfighting, the Su-75 acts as its eyes and ears as well as a missile carriage for BVR.
Remember, the F-35 isn't a fully stealth-optimized design. The bumps on the underside create RCS spikes at certain angles and azimuths, while, like the Su-75, the auxiliary air-inlets on the underwing create RCS spikes as well, which at least can be heavily treated by RAM.
The F-35 is a strike fighter that relies more on its stealth and sensors, with the F-35B being restricted to 7 G and the F-35C being restricted to 7.5 G. But if the aircraft relies on its stealth and sensors (i.e, BVR specialist), you can beat it in that arena, especially when you consider that stealth design isn't that hard; just get a flying dorito like the Hopeless Diamond and slap RAM on it. The challenge is balancing stealth with maneuverability, payload, and range, but if you want to sacrifice those factors just to beat the F-35 in stealth-land, it's not that hard to do so.
If you come up with the tail wing as your only justification for "purer stealth" or whatever that means, I should first ask you about what an "impure stealth" would be and also gotta tell you that its not that simple to say that the Checkmate has better low observability characteristics just because it has less tailwing because on the flipside it has the nose mounted (non-stealth) IRST that non of the American and Chinese counterparts you've mentioned have.
Furthermore there are some cues of J-20 at least trying to mimic what the Americans are trying to do with F-35's avionics which is not the case for the Russians.
Care to elaborate? Seems a bold claim, considering the dearth of confirmed information on the J-20 avionics suite in particular, and from what superficial examination of imagery can offer, no such disparity emerges.
He's talking about the apparent EODAS / EOTS system on the J-20.
@Maro.Kyo
The perfect stealth shape is some sort of diamond. The more you deviate from it, the less stealthy you are. Every additional wing platform, every additional bump, etc, adds to RCS.
Pure stealth was roughly solved with the original Lockheed demonstrator. The challenge is more to add payload, range, speed, maneuverability etc.
On the tail shape stuff, when you compare the YF-23 to the F-22, the YF-23 has no LERX and a V-tail. The F-22, in contrast, has LERX, V-tails, but also a tail elevator. The addition of the tail elevator adds another surface to the plane, whose emissions end up being reflected into the main wing and from there back into the original emitter.
Applied to the Checkmate, what you see is that there's a LERX from the underbay inlet, but there's no vertical stabilizers. It is, based on the layout, "purer" stealth than the F-35 or F-22 for this layout. If the proposed JH-XX ever comes online, it'd also be purer stealth by adopted a V-tail only layout as opposed to canards + main wing + tail on the J-20.
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Of course, the devil's in the details. The design of the intake is questionable, as are the tailfin intakes. The rear of the main wing shows lazy planform alignment, although thankfully it's on the rear of the main wing, not the front. Someone ought to do an RCS study on the Checkmate so we can have an idea of exactly how stealthy it is / can be.
paralay
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Text on the drawing
LTS Light Tactical Aircraft
side view 29.45 m2
top view 80.54 m2
front view 6.48 m2
volume 49.72 m3
wing area 58.2 m2
average aerodynamic chord
center of mass
LTS Light Tactical Aircraft
side view 29.45 m2
top view 80.54 m2
front view 6.48 m2
volume 49.72 m3
wing area 58.2 m2
average aerodynamic chord
center of mass
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excellent
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paralay
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RSC ~ 0.2 m2 like the F-117
Claiming that it's "uber-low-RCS" is a bit of a strawman. I'm simply stating that with the right design and parts, it could be a stealthier aircraft than the F-35. That's to say, something in the range of 2-5 dBsm advantage over the F-35 in terms of minimal RCS. "Uber-low-RCS" design implies XLO; i.e, closer to purported NGAD than simply having a YF-23 vs YF-22 advantage over the F-35.
I am more interested in rumors on what the Russians are planning for the Checkmate; the Su-57, compared to other 5th gens, places significantly less priority on stealth than the American 5th gens or even the Chinese 5th gens. A complementary fighter intended to cover the Su-57's stealth weakness is to be expected, since if the Su-57 can't get into WVR, it can be deployed with something that can.
@paralay
Problem is that the Russians and Americans use different measurements of RCS. The Americans claim the F-22 is a -40 dBsm aircraft, which is likely true for its minimal RCS. The Russians claim it's a -10 dBsm aircraft, which is more likely to be an average of its total RCS. Correspondingly, the Su-57 is claimed to be a -4 dBsm aircraft and you're claiming, presumably from Russian sources, that the Checkmate is designed to be a -7 dBsm aircraft.
Well not only EODAS-like system but other sruff like directional highspeed datalink as well as CNI suite with 4 pi steradian coverage, potentially SDR as well. Those suggest that the J-20, at least hardware-wise is able to try doing what F-35 can.
I wouldn't go beyond that because I'm not much of an expert regarding the software capabilities of the Chinese and am pretty sure the public inofrmation regarding those matters are also scarce, compared to that of F-22 and F-35 which are surprisingly, more public than what one would initially think.
Anyways back to Checkmate, if you already know so well, I'm not sure why you got to talking about anything "on paper" in the first place, as you already know that anything "on paper" doesn't really add up to convert into reality. Also obviously, a flying wing is practically the most optimal design for stealth, especially broadband. But back to the reality, the biggest thing we could learn from the ATF program was the fact that both the YF-22 and YF-23 suffice to fullfill USAF requirements. It's probably true what the NG engineers were and are claiming, that the YF-23 was harder to find, but it was not a difference that could turn the deal.
Most importantly, you would already know that stealth is not just how a plane looks like. From this perspective I am doubtful anyone else other than the Americans are able to do what they've ultimatley achieved with F-35's avionics. I'm not going to argue that the Russian engineers are just as much talented as their "western" counterparts but it is also hard to argue that the Russians would have a hard time bringing similar systems in terms of sophistication and capability out of their pocket all things considered.
And therefore it is very hard to agree on your opinion of the Checkmate being able to match F-35 in terms of its "stealth" and acting as a F-35 killer.
Acatomic
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I wonder if that means that if you have KOEPS-75, you lose the ability for self (laser) defence? Or they found a way to integrate laser defence into (and this is highly speculative) KOEPS-75?
Acatomic
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Oh, they would make a nice NATO aggressor squad for Russians to practice onThe Ministry of Defense may consider the purchase of Checkmate fighters under the GPV
Deputy Prime Minister Yuri Borisov pointed out that foreign customers are always interested in whether the native armed forces take the equipment they offer for export.
Минобороны может рассмотреть вопрос закупки истребителей Checkmate в рамках ГПВ
Вице-премьер Юрий Борисов указал, что иностранные заказчики всегда интересуются, берут ли родные вооруженные силы ту технику, которую предлагают на экспорт
Acatomic
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Let's be objective here. OLS on Su-57 and Checkmate (specially when not in use) does have RCS treatment. There are some RCS penalties but they're nowhere near as big as some people are trying to portray.
As for what gives you a bigger RCS penalty, OLS or moving tails on F-35? IMHO tails bring a bigger penalty.
Flying wings aren't perfect stealth shapes either; they're still one step removed from a flying diamond but have better aerodynamic characteristics. They called it a "hopeless diamond" for a reason; i.e, the design was closer to a missile than an aircraft.
As far as the rest of the discussion, you're discussing sensors and avionics, which was NOT the RCS question originally proposed. My impression is that Russian avionics are usually more primitive than Western or even Chinese avionics. The Su-57, notably, does not feature an EODAS suite like the F-35, but rather employs a IRST.
Thing is, avionics can be upgraded relatively easily by swapping out parts. Airframe design, on the other hand, is more set in stone.
The MiG-29 series is not a good example because it had a carrier-capable version, a FBW version, and a substantially upgraded version with TVC. The Su-27 family, on the other hand, saw a strike derivative (Su-30), a carrier derivative (Su-33), a fighter-bomber version (Su-34), and a substantially upgraded version (Su-35) featuring TVC and probably the best PESA radar on an air superiority fighter.
The interest in the shape, contrary to @overscan (PaulMM) pooh-poohing shape analysis is more that, the details can be fixed. Let's say the Su-75 is not strong RCS; Paralay's 0.2m RCS claim puts it below the F-22 and likely below the F-35 as well. But, however, if the RuAF makes orders, if the InAF makes orders, the Su-75 can be what the Su-57 is not, that is to say, a live program that makes money for the Russian MIC and is worth investing in.
Take a look at the J-20, as an example. It is relatively stealthy, probably VLO in certain angles, but it has design flaws that limit its stealth. The ventrals, for instance, were things that wall-climbers were hoping could be removed, but ended up on both the prototype and the production model. Part of the issue is the immaturity of Chinese engines; the aircraft was intended for the WS-15, but it's still making do with WS-10s. If WS-15s reach maturity and reliability, come with TVC (as wall-climbers are reporting), then the ventrals are no longer needed. The basic aerodynamic design of the J-20 can actually remove many parts that dampen its stealth (but not the canards, which are too fundamental to its aerodynamic scheme), with powerful TVC engines compensating for aerodynamic shortfalls, but that's a question of how much development the J-20 sees.
If we apply the same analysis to the Su-75, even if the Su-75 is not stealthy now, especially since they're trying to reach a 30 million cost target, the basic aerodynamic design has very high potential in terms of stealth. If I'm saying the devil's in the details, the details can be changed if the program shows success and the RuAF / export customers are willing to put up with higher costs / engine-reliant performance in return for greater stealth.
The same applies to the avionics. a Su-75 derivative whose relation to the Su-75 is the same as that of the Su-35 vs the Su-27 is going to see better avionics. There might be no design for EODAS (which requires apertures, which could explain the better range of the Su-75 vs the F-35, the Su-75 simply replaces space allocated for EODAS with fuel tanks), but data-linking Su-75s can achieve a comparable effect.
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Come to think of it, does anyone have a radar aperture measurement for the Su-75? For comparison purposes, the F-15's 950mm, the F-22's 925mm, the Flankers are 1000mm, the F-35, Eurofighter, F-18 are 700mm, the Rafale's 600mm, and the F-16's 660mm. The choice of intake on the Su-75 is going to make it hard to get a large radar aperture.
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I took an estimate from @paralay 's chart, which will probably need updating as time goes on. 1.14 diameter on the radome, which on a 75% scaling factor gives 856 mm and on a 80% scaling factor gives 912 mm.
I'm suspicious because the intake design (half-cowl) suggests the radar should be much smaller, but this is pretty huge. The radar diameter should be about 29% larger than on the F-35, implying 29% greater range, all other factors being equal (which they're not). The radar size is roughly equivalent to that of an F-22.
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LMFS
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And who says the EODAS is a superior solution to a 360 deg IRST that, on top of allowing way better optics, integrates DIRCM and has a smaller footprint on the plane?
As far as I know, Su-35 already has all around IR apertures BTW
Well, again - how do you figure all that, considering so little information is available on the systems aboard either of these aircraft, but especially the J-20 that you're so sure of has all these features?
Funnily enough, since you picked data links as an example, I can give you evidence that the Su-57 does in fact have these capabilities.
View: https://twitter.com/krakek1/status/1405574727675039744
Now, for the J-20... *
* Not necessarily saying it doesn't have all this, just making the point that it's at best unconfirmed right now, while for the Su-57 we actually have decent evidence - so claiming it's the other way round is a brave thing to say.
Unless you know what kind of RCS treatment has been done to which extent, you can't say much about it. Also having an RCS treatment on its rear end for RCS reduction when not in use doesn't really sound all that useful considering the fact that Checkmate would seriously need its IRST in operation when fighting low-rcs objects and needs higher track resolution.
Also, reiterating you, as for what's a bigger drawback in terms of RCS, a planform aligned and RAM/RAS covered wing doesn't really sound all that much of a disadvantage relatively to a bulging structure right at the front of the aircraft, fully exposed.
Obviously there's a reason why I used the word "practically".
Well, you're the one who came up with the argument of Checkmate being a plane with "aiming for a fighter capable of killing the F-35 in a stealth vs stealth fight". In such case, its obviously important to consider the avionics. Also even when assuming that Checkmate's avionics system is highly open, plug-and-play structure, having that possibility is one thing where as actually realizing said capabilities is another.
I'm deeply sorry to be only able to tell you that such information are the ones I obtained from non-English speaking forums, where few of the forum members could speak Chinese and regularly go deeper into the topic of Chinese weaponry than simply browsing Chinese websites but rather digging for Chinese research papers. Since I haven't saved all those individual threads and documents, I can't present my evidence on the notice and therefore you could simply ignore my argument as worthless. The choice is yours.
But I've got to tell you that the Chinese are indeed trying to mimic the Americans. Acquiring 3d airspace track image using real time optical detection and IFF interrogation for example. Their effort in the data fusion sector is quite impressive for that matter. There are a lot more to talk about as well but I'll talk about that on other notice if possible on other threads since this is a Checkmate thread. I know that the Su-57 has S-111N coms system which you have mentioned but that doesn't go much further than what I've mentioned. If the Russians are utilizing a fully integrated CNI system embedded on complete IMA comparable to Pave Pace is rather my question. From my knowledge I don't think anyone has done that other than the Americans and potentially the Chinese, although the Chinese system would probably be inferior.
Well, there is more than one way to implement an IMA, which is nowadays used in a wide variety of aircraft, including many business jets and airliners such as the 777, A380, 787 and A350. Rafale also deploys an IMA and so does Gripen NG in a rather novel way - this isn't such a unique feature as you seem to think it is.
As for the Su-57, have fun with this:
Yes, well IMAs were in use ever since the 90s and I know that, but I seriously doubt that the Gripen or Rafale IMA would have the same sophistication comparable to the Pave Pace architecture. There are obviously a distinct difference between JIAWG and Pave Pace although both of them are "IMA".
Well, there is more than one way to implement an IMA, which is nowadays used in a wide variety of aircraft, including many business jets and airliners such as the 777, A380, 787 and A350. Rafale also deploys an IMA and so does Gripen NG in a rather novel way - this isn't such a unique feature as you seem to think it is.
As for the Su-57, have fun with this:
As for the Russian IMA structure that you have informed me of, I really appreciate it. Thank you.
Acatomic
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OLS RCS reduction has been done in X band and it's sufficient to reduce detection range of opponents radar - lower then that of OLS's detection range.
paralay
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The nose of the LTS corresponds to the nose of the Su-57, so the N036 radar can be installed there
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EODAS's selling point is that you have constant all-azimuth / all-angle monitoring of assets around you. That's how the F-35 gets away with poor rear visibility. Moreover, EODAS is usually paired with an EOTS that presents strong frontal surveillance / tracking. On the F-35, the EOTS is designed for air-to-ground missions, on the J-20, it's designed for air-to-air. Of course, I've mentioned that the EODAS on the F-35 and J-20 is going to detract from usable airframe volume, since unless you're satisfied with a simple fixed lens, you're going to have to put optics, large sensors, and so on onto each EODAS port.
In other words, I see EODAS vs no-EODAS as a trade-off in terms of usable volume and weight. EODAS + EOTS is superior to IRST in terms of capability.
@Maro.Kyo
Regarding designing an F-35 killer, I think the main selling point is the radar aperture size on the Su-75. It's 25% larger by diameter, which translate to, all other aspects being held equal, 25% greater range.
The information Paralay is suggesting, alongside the Russian figures for the F-22's RCS, suggest that the Su-75 is half as stealthy as the F-22, which would translate to roughly a 19% increase in detection and tracking range. With the larger radome, and assuming the Russians don't drop the ball on the AESA, the Su-75 only needs to be within the same inferiority to the F-35 for the Su-75 to have a radar detection range advantage vs the F-35.
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Of course, in reality:
-The American micromissiles (SACM, but more importantly MSDM) are a gamebreaking change to missile capabilities and portend an end to BVR combat, stealth or no stealth. Micromissiles that can effectively track and destroy enemy missiles (and @LMFS , this is where EODAS is superior to IRST) are game-changing. The Russians have very small dogfight missiles (such as for the Su-57's side bays) that are working toward to that direction, but the Chinese have nothing.
-The minimal RCS of the F-35, according to some Chinese studies in the 10 GHz band, is -50 dBsm. This is for a metallic model without RAM. This level of stealth design is extremely hard to compete with.
IIRC when I did measurements for the Su-57, it's roughly a 1.2-1.3 m diameter radome, arguably larger than that on the J-20. Your diagram of the LTS / Su-75 shows a substantially smaller nose.
paralay
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AFIK - Ventral fins are usually added to the aerodynamic design to provide yaw stability at high mach numbers to prevent supersonic departure, although they may also be useful for yaw stability at high AOA. Not sure how TVC, at least as implemented on the F119 and Su-30/-35/-57 (2D vector only, although differential roll control can provide some yaw input on the Sukhois), allows the removal of the ventrals. At a minimum, you would require full 3D TVC for active yaw control.
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