Sukhoi T-75 LTS (CheckMate)

[icyplanetnhc (Steve)]

The duct is a flexible shape, while the engine is not. It is smaller in diameter, and has no ancillaries or need to provide access for maintenance and exchange as the engine does. I did the effort of checking layouts in 3D and came to a design basically identical to the LTS, there is no way of achieving such slender fuselage and reduced cross section with weapon bays parallel to the engine, it simply does not work, by a wide margin. Much less if the engine is as big as the F135.

I understand the LHA constraint, but if you notice the position of the engine, it is like two-three meters to the front compared to how it could be without surpassing the current length of the plane, and very much unlike in planes like LTS, JAS-39 or F-16 which are designed for outstanding aerodynamics. So I conclude that the main factor was the STOVL requirement, in the sense of getting the main engine's thrust as close as possible to the CoG. This, together with the need of the lifting fan behind the cockpit, forced the bays to the sides of the engine and ultimately placed a cap on the dynamic capabilities of the plane. IMHO

The diffuser section in front of the engine should have a circular cross section to minimize distortion for at least a duct diameter's length worth, ideally more. I would say that it's not the STOVL requirement itself that forced a short fuselage on the F-35, but when combined with other requirements, particularly the Navy's. The original ASTOVL/CALF design, which only had CTOL and STOVL variants, was a canard delta, and the overall length was considerably closer to the fuselage length. When Navy requirements for carrier recovery were factored in, it was one of the major reasons that the configuration changed to a wing-tail design, with the stabilitors extending well behind the fuselage. That said, all these factors and requirements shouldn't be viewed in isolation, as some of the canard delta configurations during JAST/JSF did extend some control surfaces well behind the fuselage. In any case, fineness ratio itself isn't something to be designed around, it's a fallout of the aerodynamic design as a whole, and there's also the fact that even without three-stream technology, the F135 isn't quite making full use of the F-35's inlet.

Back to the LTS, towards the end of the Cold War, it appears that Soviet air arms had an institutional aversion to single-engine tactical fighters, which carried into the Russian Air Force. Let's see if this has been shaken off.

 

[Dragon029]

Randomly found on Fb, I've tried to reverse search the picture expecting to find the original source and better resolution, without success.

I don't know the source but this larger version was posted on Reddit yesterday or the day before:

 

[jeffb]

 

[tequilashooter]

2026 sounds like it sure is going to be a magical year in profit for the LTS and Amur rockets if as advertised.

 

[helmutkohl]

^ thanks for that image

here are some more overlays I've made by pasting two of the same pics over each other


Overlap by engine


By wing



By radome tip


By cockpit. it seems the Su-75 has a slighty larger cockpit

 

[paralay]

@paralay
Did you manage to refine your estimations of cross sectional area for Su-57 and Su-75?

http://www.paralay.ru/paralay_tab.xls

 

[Scar]

The more i look at this project, the more i love it. Smartest weapon system, after T-34, IL-2 and MiG-21. The level of unification on equipment, technologies and whole parts of the airframe migrated from Su-57 delivers orgasm to my inner project(-budget)-manager. Pray for it to be realized ASAP.

 

[TMA1]

Given that the duct diameter isn't much smaller than the engine diameter, and the inlets run over the weapon bays, I wouldn't consider the weapon bay placement to be the factor. The F-35's lower fineness ratio has more to do with the fuselage length, which was limited by the deck lifts of LHAs, combined with the very high fuel fraction and weapon bays sized for 2,000 lb ordnance. The LTS isn't constrained in this regard, which can allow for a more slender design, although it's also sized for an AL-41F1-sized engine which is considerably smaller than the F135, which actually doesn't make full use of the F-35's inlet flow (inlet flow was increased in 2005 during SDD, and the F136 would have made full use of it).

The duct is a flexible shape, while the engine is not. It is smaller in diameter, and has no ancillaries or need to provide access for maintenance and exchange as the engine does. I did the effort of checking layouts in 3D and came to a design basically identical to the LTS, there is no way of achieving such slender fuselage and reduced cross section with weapon bays parallel to the engine, it simply does not work, by a wide margin. Much less if the engine is as big as the F135.

I understand the LHA constraint, but if you notice the position of the engine, it is like two-three meters to the front compared to how it could be without surpassing the current length of the plane, and very much unlike in planes like LTS, JAS-39 or F-16 which are designed for outstanding aerodynamics. So I conclude that the main factor was the STOVL requirement, in the sense of getting the main engine's thrust as close as possible to the CoG. This, together with the need of the lifting fan behind the cockpit, forced the bays to the sides of the engine and ultimately placed a cap on the dynamic capabilities of the plane. IMHO

The Su-57 is intermediate size compared to what the original heavyweight fifth generation fighter, the MFI, was supposed to be.

And yet the capacities are not worse, well, maybe the top speed, but not payload or range, as far as I know. The progress in systems technology allowed them to do pretty much the same with a smaller airframe. By the beginning of XXI century, the MFI concept had already been surpassed in so many ways it needed replacement.

It's a similar situation where the F-35 is considered to be the "light" fighter compared to the F-22, yet the F-35A's empty weight is similar to the F-15C's.

Yes, the weight and size creep from 4th to 5th gen makes it necessary to re-evaluate what a light fighter is. I would say the challenge after the F-35 was to proof that a "light" fighter could be designed around the same engine of the "heavy" brother. And that is a tough challenge, once we see that the LTS with current engines can only afford an 8g airframe with no internal cannon to keep its TWR up there with the best. Most other manufacturers had to settle for a twin engine 5G fighter, only Lockheed could afford a single engine design thanks to a monster engine like the F135, and still they could not keep it the size of the F119.

The Su-35 was originally a Sukhoi-initiated effort meant for export, but after struggling to find export customers, the Russian Defense Ministry decided to procure it. I'm not calling it a "crazy adventure", but simply that the impetus didn't come from the Defense Ministry, similar to the case with the Su-35. Not that it's necessarily a bad thing.

Yeah, MoD allow themselves to be convinced by the industry quite often. In the case of the Su-35, the reason was also the need to bridge the 4th - 5th gen gap. This was also needed for the VKS, hence why I doubt also in this case, that there was not a basic common understanding between MoD and MIC about the expediency of making the effort of designing and fielding an almost new plane. For VKS it had the additional advantage of providing a very much needed B plan in case the PAK-FA program suffered delays and setbacks, as any complex program normally does. Come 2018, Borisov could afford to bluff that they had no problem buying further the Su-35 and shortly thereafter we had the news of a 76 units deal for the Su-57 with 20% price reduction from the original quotes. This leverage would not have been there without the Su-35...

I remember when the checkmate was unveiled and everyone got a kick out of how close your LMFS model was to checkmate. Seriously good work, m8

 

[Scar]

I don't know the source but this larger version was posted on Reddit yesterday or the day before:

Please, can you provide the link to r/ where you found this photo? Thank you in advance.

 

[GARGEAN]

MoD simply does not want to paint themselves into a corner by promising anything before the product is mature enough

Good joke when talking about Russia tbh.

 

[emile1211]

This Layout was concieved decade ago by Chinese Enthusiast.

 

[Scar]

This Layout was concieved decade ago by Chinese Enthusiast.

Have some similar elements, but very different, overall. Northrop paper project MRF-54E has much more of similarity.

 

[LMFS]

The diffuser section in front of the engine should have a circular cross section to minimize distortion for at least a duct diameter's length worth, ideally more.

Yes, that section is like 1 meter long, but the duct itself is a highly flexible element regardless. LTS, F-35 or F-22 are all good examples of that.

The original ASTOVL/CALF design, which only had CTOL and STOVL variants, was a canard delta, and the overall length was considerably closer to the fuselage length.

I am not very knowledgeable about those, but the Lockheed model I've seen has the engine displaced to the front and no apparent possibility of placing the bay in at the optimal location because of that engine position and the fan.

In any case, fineness ratio itself isn't something to be designed around, it's a fallout of the aerodynamic design as a whole

I assume the reduction of cross sectional area and optimization of supersonic drag are among the absolutely top criteria for designing a fighter and should be kept present from the very beginning when selecting a layout, because they will deeply impact every performance parameter of the plane, propulsive needs, fuel consumption, payload and so on. It is not surprising to me that both X-32 and F-35 resulted in very thick planes and both had bays at the sides of the engine when they had the same STOVL requirements resulting in engines taking the center of the fuselage.

Back to the LTS, towards the end of the Cold War, it appears that Soviet air arms had an institutional aversion to single-engine tactical fighters, which carried into the Russian Air Force. Let's see if this has been shaken off.

I have never seen anything official about this, but Borisov mentioned something along those lines recently. I can understand such concerns on naval fighters or when your military is cutting corners in maintaining the fleet, like in the 90's in Russia, but prior to that they had many and very successful single engine planes. Added to current engine reliability and huge economic savings, I don't think any real reason exists not to have light single engine planes in the VKS.

http://www.paralay.ru/paralay_tab.xls

Thank you paralay, I think 8.5 vs 7.2 sqm is maybe a bit off... Previously you had like 10 sqm for the Su-57 right?

Good joke when talking about Russia tbh.

Why? They are normally reluctant to commit to new proposals until the developer has managed to bring them to fruition and thoroughly demonstrated its properties and tactical usefulness, like the BMPT recently. You can argue sometimes they have to swallow equipment they don't like, but at least they try not to be used as useful idiots for exercises in happy engineering, and that is fully correct IMO. Even with the Su-57 they did not order until they saw everything they needed at the prices they wanted, and that was their own program...

 

[paralay]

The midsection of the Su-27 is 4.18 m2, the front view area is 10 m2.

We can assume the midsection of the Su-57 and LTS Front view area:
Su-57 - 9.34 m2 (according to another drawing 8.5 m2), midsection - 9.34 m2 * 0.418 = 3.9 m2
LTS - 7.29 m2, midsection 7.29 m2 * 0.418 = 3.05 m2, but this is not accurate, of course

 

[LMFS]

Some quotes from TASS' special, specially interesting are the ones from Strelets regarding Syria and the joint operation of Su-57/75 and drones, all relevant to understand its potential use in the VKS

Analysis of the results of the use of strike aircraft systems in Syria has shown that the capabilities of heavy twin-engine aircraft systems are redundant to perform most tasks
-------
Today, the trend towards the unification of the fleet of aircraft is gaining strength in the world. Due to the large degree of interproject unification, the joint use of Su-57, Checkmate and unmanned aerial vehicles can form an optimally balanced fleet for various tasks with minimal operating costs and high combat potential.
-------
When creating the aircraft, the designers paid special attention to maintaining a rational balance between proven technical solutions and breakthrough technologies, capabilities and cost of the machine. Thanks to this, Checkmate received a unique combination of flight characteristics, combat effectiveness at an affordable price and low cost of flight hours

Mikhail Strelets, Chief designer of LTS

The aircraft was initially created as a platform for a whole family of aviation complexes. We are planning to create an optional manned and unmanned modification of the aircraft.

The unmanned modification is not just a fashion statement. We are already at an early stage of the project laying in it ample opportunities for use in the framework of network-centric military operations. The aircraft will be able to exchange information and target other aircraft systems and unmanned aerial vehicles. The use of unmanned versions of the machine will allow, among other things, to implement new tactical techniques

Yuri Slyusar, General Director of UAC

The modern conflict is not just a confrontation between planes and tanks. Today, first of all, it is the struggle of the economies. To gain the upper hand, you need to use resources more rationally than your opponent does, respond asymmetrically, and be more effective

Bekhan Ozdoev, Industrial Director of the Arms Cluster of Rostec Corporation

Как устроен первый российский однодвигательный истребитель - в спецпроекте ТАСС

На рынке боевой авиации представлены десятки современных образцов боевых самолётов. Однако у Checkmate есть возможность опередить конкурентов и стать одним из основных продуктов российского оборонного экспорта

su-checkmate.tass.ru

 

[GARGEAN]

Why?

Because media part of russian MoD is an absolute junk with insane amount of stupid claims, especially in regards of timelines.

 

[Scar]

Because media part of russian MoD is an absolute junk with insane amount of stupid claims, especially in regards of timelines.

The Holy Truth been said. Amen

 

[tequilashooter]

Depends, its like that one time i saw in a thread how every user was against the thought of the su-57 having internal hypersonic air to ground weapons than all of a sudden everyone did a complete 180 when they decided to reveal its name later, good times. Seems that "media part" was right so immediately discarding everything as BS is something I wouldnt do assuming if lessons were learned or not. So far the behavior of this board got a little better since no one immediately has thrown doubts or got pissed at the thought of the S-550(will make a thread soon of it until some characteristics are disclosed) as of yet or other insane projects like the Yakroma radar operating in 4 different bands so kudos to that.

 

[LMFS]

Because media part of russian MoD is an absolute junk with insane amount of stupid claims, especially in regards of timelines.

Media part can be as stupid as you want, the important part is that the policies and performance of Russian MOD and MIC are head, shoulders and waist above the international standard. They exercise one thing called risk management almost to perfection and that is making a real difference in the international balance of power.

 

[kaiserd]

Because media part of russian MoD is an absolute junk with insane amount of stupid claims, especially in regards of timelines.

Media part can be as stupid as you want, the important part is that the policies and performance of Russian MOD and MIC are head, shoulders and waist above the international standard. They exercise one thing called risk management almost to perfection and that is making a real difference in the international balance of power.

Sounds like an enthusiastic fan.
Or employee copying a script.

 

[tequilashooter]

Size comparison of LTS and F-35 just for the fun of it.

 

[TMA1]

This Layout was concieved decade ago by Chinese Enthusiast.

That is pretty rad but it doesnt look like the checkmate. Scar is more on the money as far as Northrop's layout goes(sukhoi seems to have gone along similar trends to those of northrop/grumman). Frankly there aren't a lot of layouts you could achieve in order to keep rcs low, have two side bays and one belly bay, and all packaged in a single engine design. I think the f-35 and checkmate is about as small as you can make a single engine fighter with those kinds of requirements. One thing I love about checkmate is the elegant air intake and ducting wrapping around the lower sides of it's belly in between the side and belly bays. A chin intake with double serpentine ducting. It is so cool. Also thinking about the f-35. As much as I dont like it aesthetically or ideologically, the fact that engineers pulled off a three branch aircraft/concept which included stovl capability is astounding.

Edit: had to reword a goofy sentence I wrote

 

[LMFS]

Sounds like an enthusiastic fan.
Or employee copying a script.

I better don't tell you what you sound like right now

@Saber
Do you have any argument at all? I am not talking about media, I am talking about MOD not committing money to a program or a buy before they see it is viable or mature enough. There are tons of such examples

 

[icyplanetnhc (Steve)]

I am not very knowledgeable about those, but the Lockheed model I've seen has the engine displaced to the front and no apparent possibility of placing the bay in at the optimal location because of that engine position and the fan.

ASTOVL/CALF configuration 140 (JAST/JSF predecessor) is a canard delta with the engine placement considerably less forward.

Yes, that section is like 1 meter long, but the duct itself is a highly flexible element regardless. LTS, F-35 or F-22 are all good examples of that.
...
I assume the reduction of cross sectional area and optimization of supersonic drag are among the absolutely top criteria for designing a fighter and should be kept present from the very beginning when selecting a layout, because they will deeply impact every performance parameter of the plane, propulsive needs, fuel consumption, payload and so on. It is not surprising to me that both X-32 and F-35 resulted in very thick planes and both had bays at the sides of the engine when they had the same STOVL requirements resulting in engines taking the center of the fuselage.

The duct wouldn't be substantially smaller in cross section than the engine, even in the diffuser section behind the throat, as during takeoff and low subsonic conditions, a substantial part of the duct in front of the IGVs should be relatively uniform in cross section. Again, it's not necessarily the cross section area itself (although the 2,000 lb class weapon bays certainly added to that), but the fineness ratio due to the length constraints that make the F-35 stubbier. The Su-57 also has weapon bays that run parallel to the engines, and in fact it was specifically designed for that to address what Sukhoi consider to be one of the biggest limitations of the F-22: insufficient payload.

And, no, fineness ratio is not what to design an aircraft around; it's a very important factor, but just one of many that goes into the overall configuration and shaping in order to meet mission requirements. Wave drag is also affected by the volume distribution (area ruling), presence of shockwave interferences.

 

[TMA1]

The duct is a flexible shape, while the engine is not. It is smaller in diameter, and has no ancillaries or need to provide access for maintenance and exchange as the engine does. I did the effort of checking layouts in 3D and came to a design basically identical to the LTS, there is no way of achieving such slender fuselage and reduced cross section with weapon bays parallel to the engine, it simply does not work, by a wide margin. Much less if the engine is as big as the F135.

I understand the LHA constraint, but if you notice the position of the engine, it is like two-three meters to the front compared to how it could be without surpassing the current length of the plane, and very much unlike in planes like LTS, JAS-39 or F-16 which are designed for outstanding aerodynamics. So I conclude that the main factor was the STOVL requirement, in the sense of getting the main engine's thrust as close as possible to the CoG. This, together with the need of the lifting fan behind the cockpit, forced the bays to the sides of the engine and ultimately placed a cap on the dynamic capabilities of the plane. IMHO

The diffuser section in front of the engine should have a circular cross section to minimize distortion for at least a duct diameter's length worth, ideally more. I would say that it's not the STOVL requirement itself that forced a short fuselage on the F-35, but when combined with other requirements, particularly the Navy's. The original ASTOVL/CALF design, which only had CTOL and STOVL variants, was a canard delta, and the overall length was considerably closer to the fuselage length. When Navy requirements for carrier recovery were factored in, it was one of the major reasons that the configuration changed to a wing-tail design, with the stabilitors extending well behind the fuselage. That said, all these factors and requirements shouldn't be viewed in isolation, as some of the canard delta configurations during JAST/JSF did extend some control surfaces well behind the fuselage. In any case, fineness ratio itself isn't something to be designed around, it's a fallout of the aerodynamic design as a whole, and there's also the fact that even without three-stream technology, the F135 isn't quite making full use of the F-35's inlet.

Back to the LTS, towards the end of the Cold War, it appears that Soviet air arms had an institutional aversion to single-engine tactical fighters, which carried into the Russian Air Force. Let's see if this has been shaken off.

"fineness ratio itself isn't something to be designed around"

Excuse my ignorance as I am a layman, but it certainly could be something you'd design an aircraft around if you wanted a stealthy supercruiser, especially if you'd be expecting the aircraft to still supercruise with export engines.

 

[icyplanetnhc (Steve)]

Excuse my ignorance as I am a layman, but it certainly could be something you'd design an aircraft around if you wanted a stealthy supercruiser, especially if you'd be expecting the aircraft to still supercruise with export engines.

No, the mission and requirements should drive the shape, not the other way around. Based on the requirements for acceleration, cruise, etc. the aircraft's geometry and propulsion would be designed and refined/iterated until the system as a whole meets the requirements. Fineness ratio has a major effect on wave drag characteristics but it's also certainly not the only one. Certainly, if your requirements place a strong emphasis on supercruise, fineness ratio may be a greater driving factor, but again it's the aircraft as a whole that has to meet a set of requirements.

Now, given that the LTS isn't a Russian Defense Ministry program of record, Sukhoi may have greater leeway in designing the aircraft around their desired characteristics that may not necessarily have to strictly adhere to a set of government requirements put in writing.

 

[TMA1]

Dont fight eachother. LMFS is bro tier and has always been helpful on the forums I've seen him on. He loves russian kit. I do too. He isnt reading from a script. I also like your posts, Kaisard, and you too, saber. Been a long time lurker and I love this site. Has something special about it. So dont be too angry at eachother.

ffs I feel like the stereotypical annoying little broski right now.

 

[overscan (PaulMM)]

If you designed a fighter purely for supercruise it'd probably look something like this:

(Nathan Kirshbaum early ATF design for Grumman)

That's a fineness ratio to be proud of....

 

[Rhinocrates]

Latest Images Of Russia’s Checkmate Fighter Shows Us Just How Big It Really Is (Updated)

Russia has billed the Checkmate as a light fighter, but that isn't really the case.

www.thedrive.com

Scroll down and...

Now, as if the marketing behind the Checkmate couldn't have gotten any weirder, there is now a Checkmate fragrance!

 

[tequilashooter]

Dont fight eachother. LMFS is bro tier and has always been helpful on the forums I've seen him on. He loves russian kit. I do too. He isnt reading from a script. I also like your posts, Kaisard, and you too, saber. Been a long time lurker and I love this site. Has something special about it. So dont be too angry at eachother.

ffs I feel like the stereotypical annoying little broski right now.

nahh theres no fighting if there was you would see posts get removed The only thing I run comparisons off of this aircraft is just needing a radar improvement, range, stealth, weapons, costs of the aircrafts seem good. I still have disagreements with LMFS on is the su-57s 2nd stage engine and proposals of engines for next gen aircrafts, but I dont think those arguements in past experiences were bad, it just that there are certain users which I am not going to say whom start going off with personal attacks when they have a disagreement. What you see here is actually very mild.

 

[LMFS]

The duct wouldn't be substantially smaller in cross section than the engine, even in the diffuser section behind the throat, as during takeoff and low subsonic conditions, a substantial part of the duct in front of the IGVs should be relatively uniform in cross section.

It is not about cross section of the air duct (which nevertheless has not ancillaries, cooling, thermal insulation or access needs), it is about the constraints a fixed shape like the engine places in the internal distribution of volumes. An air duct can be shaped to conform to other non flexible volumes, while engines or weapon bays cannot. If you place the engine between the bays you get a massive cross sectional area as a result. You just need to take the F-35 or X-32 and analyse them, it is fairly obvious to see what the minimum needed dimensions are.

Again, it's not necessarily the cross section area itself, but the fineness ratio due to the length constraints that make the F-35 stubbier.

If you plane is shorter than others and you make it also thicker, you are going to end up with bad supersonic drag. On the other hand, your propulsion needs to be sized not for your Cd, but for your overall drag at the end of the day, so overall cross sectional area indeed is relevant.

The same length with another engine position would have resulted in a totally different result. See some similarities in the engine position below? (agreed the Yak is an even more extreme example)



Consider the F135 being placed right in line with the trailing edge of the elevators in the picture below (thanks to paralay) and no lifting fan, a weapon bay of the same length of the current ones would be created right at the centerline of the plane in front of the engine, resulting in much smaller cross sectional area, improved fineness ratio and quite likely better area ruling. Of course there would be interference with the air duct, that is why a ventral intake is the leanest option for such layout. To me it seems very hard to dispute that STOVL is indeed behind the very particular internal distribution of elements in the F-35.

The Su-57 also has weapon bays that run parallel to the engines, and in fact it was specifically designed for that to address what Sukhoi consider to be one of the limitations of the F-22: insufficient payload.

The Su-57 is a twin engine plane, in such situation placing weapon bays in line (unlike the parallel ones in the F-22) between the engines is actually the best layout, because it creates a bay space of ca 10 m length and 1.25 m width with is much longer and thinner than it would be if the bays were shorter and in front of the engines. The frontal section of the aircraft has two contributing elements that cannot be avoided, engines/intakes and cockpit. The Su-57 places the bays right in line with the cockpit, at essentially no expense in terms of cross sectional area. So it gets a minimally bigger transversal area than the F-22 (which has a very compact fuselage) with much increased bay space and way bigger intakes.

And, no, fineness ratio is not what to design an aircraft around; it's a very important factor, but just one of many that goes into the overall configuration and shaping in order to meet mission requirements. Wave drag is also affected by the volume distribution (area ruling), presence of shockwave interferences.

Yes, that is why my wording was about supersonic drag as a whole. Like said above, we are talking about similarly sized planes with similar internal volume needs determined by engine size, fuel capacity and weapon bay volume. If you distribute the elements along the longitudinal axis instead of the transversal one, you get at the same time less cross sectional area and better fineness ratio. So you improve both performance factors at the same time for a way better final result. The difference in propulsive power vs speed for the two planes is a clear evidence that what I say is indeed in line with the reality.

 

[TMA1]

Dont fight eachother. LMFS is bro tier and has always been helpful on the forums I've seen him on. He loves russian kit. I do too. He isnt reading from a script. I also like your posts, Kaisard, and you too, saber. Been a long time lurker and I love this site. Has something special about it. So dont be too angry at eachother.

ffs I feel like the stereotypical annoying little broski right now.

nahh theres no fighting if there was you would see posts get removed The only thing I run comparisons off of this aircraft is just needing a radar improvement, range, stealth, weapons, costs of the aircrafts seem good. I still have disagreements with LMFS on is the su-57s 2nd stage engine and proposals of engines for next gen aircrafts, but I dont think those arguements in past experiences were bad, it just that there are certain users which I am not going to say whom start going off with personal attacks when they have a disagreement. What you see here is actually very mild.

Alright. Thanks homie.

Latest Images Of Russia’s Checkmate Fighter Shows Us Just How Big It Really Is (Updated)

Russia has billed the Checkmate as a light fighter, but that isn't really the case.

www.thedrive.com

Scroll down and...

Now, as if the marketing behind the Checkmate couldn't have gotten any weirder, there is now a Checkmate fragrance!

I hope it is legit. Ruskies are so weird. You slav, you win.

 

[icyplanetnhc (Steve)]

It is not about cross section of the air duct (which nevertheless has not ancillaries, cooling, thermal insulation or access needs), it is about the constraints a fixed shape like the engine places in the internal distribution of volumes. An air duct can be shaped to conform to other non flexible volumes, while engines or weapon bays cannot. If you place the engine between the bays you get a massive cross sectional area as a result. You just need to take the F-35 or X-32 and analyse them, it is fairly obvious to see what the minimum needed dimensions are.
...
If you plane is shorter than others and you make it also thicker, you are going to end up with bad supersonic drag. On the other hand, your propulsion needs to be sized not for your Cd, but for your overall drag at the end of the day, so overall cross sectional area indeed is relevant.

The same length with another engine position would have resulted in a totally different result. See some similarities in the engine position below? (agreed the Yak is an even more extreme example)
...
Consider the F135 being placed right in line with the trailing edge of the elevators in the picture below (thanks to paralay) and no lifting fan, a weapon bay of the same length of the current ones would be created right at the centerline of the plane in front of the engine, resulting in much smaller cross sectional area, improved fineness ratio and quite likely better area ruling. Of course there would be interference with the air duct, that is why a ventral intake is the leanest option for such layout. To me it seems very hard to dispute that STOVL is indeed behind the very particular internal distribution of elements in the F-35.

You're solely focused on the fuselage cross section without considering the overall cross section that can be highly affected by wing placement and other factors that goes into package, which was a point I've been hinting at. This is ASTOVL/CALF configuration 141B, one of the earlier configurations that would lead into Lockheed's JSF design.



Notice with the canard delta how much more to the rear the placement of the wings are, as well as how much closer the nozzle is to the trailing edge of the wings, without nearly as much of the empennage extending behind. What this enabled was for the part of the wing with the greatest span, and thus largest contribution to cross section, be placed behind the weapon bays. Currently, the F-35's weapon bays coincide with the wingtips, which is likely driven by a wing tail configuration (lowest risk for Navy's carrier recovery) combined with other factors such as length constraint from LHAs. It's the combination of all factors, rather than STOVL by itself, is what contributes to the F-35's rather large cross section.

That said, a canard delta configuration is not necessarily immune to these problems, as it was not refined/iterated into a final design where we would know where everything is placed. But being singularly focused on weapon bay and engine placement misses the bigger picture of other factors that go into packaging.

But as I've said, it's mission and requirements that drive configuration, shape, and overall design. Scrutinizing the specifics of a particular component placement in isolation is frankly rather pedantic. There's also the fact that the LTS hasn't flown yet, and has somewhat lower payload capacity (two 700 kg weapons in the main bay, compared to two 2,000 lb (900 kg) weapons (the stations are actually rated for 2,500 lb) in the F-35A/C), and that the F-35 is not drag limited at Mach 1.6 even with the F135 that doesn't make full use of the inlet; I doubt maximum speed will be pushed beyond that even with enhanced engines, there isn't the requirement or the practical need to do so.


Unspecified F-35 variant envelope

The Su-57 is a twin engine plane, in such situation placing weapon bays in line (unlike the parallel ones in the F-22) between the engines is actually the best layout, because it creates a bay space of ca 10 m length and 1.25 m width with is much longer and thinner than it would be if the bays were shorter and in front of the engines. The frontal section of the aircraft has two contributing elements that cannot be avoided, engines/intakes and cockpit. The Su-57 places the bays right in line with the cockpit, at essentially no expense in terms of cross sectional area. So it gets a minimally bigger transversal area than the F-22 (which has a very compact fuselage) with much increased bay space and way bigger intakes.

That's a...very optimistic interpretation. Just to apply your own arguments, the F-22's weapon bays are right in line with the intake, after which the inlets snakes upwards and inwards to become inline with the cockpit/front fuselage, also resulting what you've just argued for the Su-57, with just about as much applicability, i.e. very little. "Way bigger intakes"? Nope. I'm getting a difference of about 5% in terms of frontal capture area from official diagrams, which is within the margin of measurement error. Mind you, in propulsion terms, 5% is not insignificant, but the actual flow field the inlets see will be different from a head on view, and given the functions that the inlet flow serves in addition to propulsion, frankly this difference is not worth noting, and I'm not even sure why it's being invoked as some kind of obvious benefit.

 

[aonestudio]

View: https://www.youtube.com/watch?v=dkboS0Fxcws

https://twitter.com/x/status/1459560131797164033

View: https://twitter.com/Rostec_Russia/status/1459560131797164033

 

[TMA1]

I want it. There is something so cluelessly dorky and based about ut.

 

[tequilashooter]

despite the long range of the aircraft and flights per cost, has the fuel capacity on it been disclosed yet?

 

[Dragon029]

Please, can you provide the link to r/ where you found this photo? Thank you in advance.

Here it is.

 

[aonestudio]

https://twitter.com/x/status/1459753490025107457

View: https://twitter.com/MuxelAero/status/1459753490025107457

 

[red admiral]

If you distribute the elements along the longitudinal axis instead of the transversal one, you get at the same time less cross sectional area and better fineness ratio. So you improve both performance factors at the same time for a way better final result. The difference in propulsive power vs speed for the two planes is a clear evidence that what I say is indeed in line with the reality.

But longer aeroplanes have more skin friction drag and mass so its hardly clear. Design is all about trade offs and without crunching the numbers its really difficult to make definitive judgments.

It also depends what constraints you're working to. e.g. the basically straight and relatively short intake duct on Su-57 is very different from the highly convoluted longer intake duct on F-22

 

[TR1]

Sounds like an enthusiastic fan.
Or employee copying a script.

I better don't tell you what you sound like right now

@Saber
Do you have any argument at all? I am not talking about media, I am talking about MOD not committing money to a program or a buy before they see it is viable or mature enough. There are tons of such examples

MOD is infamous for borderline bankrupting shipyards with their promises, late payments, and (to add insult) lawsuits over timelines they themselves caused.
There are many many other examples.