Sukhoi T-75 LTS (CheckMate)

[overscan (PaulMM)]

The movable bits next to the engine look like split airbrakes rather than general control surfaces.

 

[LMFS]

The movable bits next to the engine look like split airbrakes rather than general control surfaces.

That function today is fulfilled by the canted tails in the Su-57 and the rudders in the Su-35, don't know to what extent that would need to be changed in the LTS. Granted that, without H-stabs, the tails would create a pitch effect besides acting as air brake, but can it be compensated by other control surfaces? If those trimmers or air brakes do in fact deflect like elevators, then they can be combined with the tails for braking and other purposes. I tend to think they have, like other control surfaces today, several functions.

That one interview with Rostec official said LTS will use first stage engine from su57 program, which made the relatively fast development of the whole plane possible.

But they talked also about having options between 14.5 and 16 tf. That means, izd. 117S, 117 and a new, until now not clearly mentioned version of the 117 with increased thrust. And then, izd. 30 with 18 tf would be the other option. That is a lot to chose from, and that can explain that the plane is configurable and that very low prices and different specs are mentioned.

 

[Silencer1]

After 30 years of secret development, fictional "MiG-37 Ferret E" evolved into the Suhkoy LTS.
Inlets and number of engines have been reconsidered, as well as overall jet-black paint in favor of cheerful pixel camouflage.
Source of picture https://www.rocketpunch.biz/completed-italeri-72-mig-37b-ferret/.

 

[kaiserbill]

I seem to recall a while back that a thrust vectoring engine with serrated petals was displayed in a factory in the Su-57/PAKFA thread.
At the time, there was confusion, as it was agreed that this wasn't the engine that was to be the final choice for the Su-57..the izd.30.

Does anyone else recall that?

I wonder if this is the platform that engine was targeted at?

 

[Dr.Snufflebug]

I seem to recall a while back that a thrust vectoring engine with serrated petals was displayed in the Su-57/PAKFA thread.
At the time, there was confusion, as it was agreed that this wasn't the engine that was to be the final choice for the Su-57..the izd.30.

Does anyone else recall that?

I wonder if this is the platform that engine was targeted at?

That was a Salyut engine IIRC, unrelated to the Saturn 30 etc, and it is quite visibly different with way more petals and so on

This one looks like the 30 nozzle that was seen in static tests and in-flight on T-50LL.

 

[Deino]

 

[kaiserbill]

I seem to recall a while back that a thrust vectoring engine with serrated petals was displayed in the Su-57/PAKFA thread.
At the time, there was confusion, as it was agreed that this wasn't the engine that was to be the final choice for the Su-57..the izd.30.

Does anyone else recall that?

I wonder if this is the platform that engine was targeted at?

That was a Salyut engine IIRC, unrelated to the Saturn 30 etc, and it is quite visibly different with way more petals and so on

This one looks like the 30 nozzle that was seen in static tests and in-flight on T-50LL.

Thanks.
Yes, I think I recall it was a Salyut product, and there was confusion about which platform it was intended for.
Thanks for the clarification.

 

[Anduriel]

Good view of nosewheel. Look's like it's indeed slightly off-axis to accomodate EOTS.

 

[kaiserbill]

Top view.

 

[Dr.Snufflebug]

Same LED panel that later T-50/Su-57 frames have on the front gear strut too.

It's not crazily off-axis but I still wonder about the weight distribution. Or you reckon that the EOTS and its supporting internal electronics would offset that? Sounds unlikely to me.

edit: Top view looks super sleek. I also noticed that the aforementioned LED landing light is in fact positioned such that it is dead center on the fuselage axis when the gear is deployed. So I guess it folds somehow? I'm willing to admit that certain details here appear quite more thought-out than I initially thought.

 

[Scar]

This EOTS annoying me more and more. Unnecessary, costly and affecting landing gear.

 

[sferrin]

View attachment 661222

Looks like the McD/NG JSF entry had a baby with the X-32.

 

[DWG]

the only two happy 5th gen aircraft

via girchenko twitter

This jet... exudes a smugness I have never seen before. Now there are two of them.

HUE HUE HUE HUE!!

Three if you count the revised inlet projected for the F-32 - https://www.thedrive.com/the-war-zo...ked-like-if-lockheed-lost-the-jsf-competition

 

[Trident]

the opposite for me. I am amazed by the reuse even seemingly of wings and vvertical stabilizers and many other bits. It is extremely clever and it is obvious at this (granted very early) stage of development that it is aerodynamically sound and seemingly functional. Sukhoi isn't full of idiots by any stretch. It is also very lovely. So I totally disagree with you. I think this, with typical flaws along the way, will succeed, and that this was a good first step.

Yes, I've started to wonder about the wings as well - they aren't actually as big as one might think on the Su-57, much of the area comes from the truly enormous centroplane. So, as jeffb mentions, we could potentially have commonality in forward fuselage & cockpit (including equipment & avionics), wings, fins, main weapons bay, landing gear and engine. It's stunning to contemplate that such a high proportion of primary structure from an aircraft *twice* the size could come together into a coherent and even fairly elegant design! I can't think of a recent example that would quite match this feat - even the F-35 squaring of the circle would begin to look downright plain in comparison. Of course, this approach must inevitably lead to a certain weight penalty (a purpose-designed landing gear for a 20 ton aircraft is going to be lighter than something optimized for a 40 ton aircraft).

The more I think about it, the more things start to make sense, though in some instances it apparently led to superfluous complexity being also carried over. Going for a single trailing edge flaperon as I've thought about for the Su-57 would give a similar degree of simplification to the Pelikan tail I considered earlier while retaining commonality.

The movable bits next to the engine look like split airbrakes rather than general control surfaces.

Like the F-16? There's no indication in close-up photos that they are split into upper/lower halves in the same way, and given the generally very detailed representation of other moving parts I doubt that's something which would have been simplified. They may play a role in airbraking though to counter any pitch-up or pitch-down tendency when the other control surfaces are splayed out differentially to create drag.

 

[Dr.Snufflebug]

The Su-25 also has split "clamshell" airbrakes, albeit on the wingtips.

There is a discernible split in these, but it doesn't appear that "engineered".

 

[DWG]

The movable bits next to the engine look like split airbrakes rather than general control surfaces.

That function today is fulfilled by the canted tails in the Su-57 and the rudders in the Su-35, don't know to what extent that would need to be changed in the LTS. Granted that, without H-stabs, the tails would create a pitch effect besides acting as air brake, but can it be compensated by other control surfaces? If those trimmers or air brakes do in fact deflect like elevators, then they can be combined with the tails for braking and other purposes. I tend to think they have, like other control surfaces today, several functions.

I'd have thought they're on the small side for air brakes, especially if you're toeing the tails in or out as a primary airbrake. OTOH as control surfaces they do potentially give you a second axis for driving the fuselage in pitch in addition to the wing-mounted control surfaces (and thrust vectoring if fitted), and optionally in roll/yaw if they can function differentially. There's some potential similarity to the inline-triplane concept Sukhoi were pushing with the canard equipped Su-27s, but IMO the moment-arms are too short for that to be really effective. At minimum they probably allow some trimming of the fuselage pitch vector separately from the flight-path vector.

 

[Trident]

I seem to recall a while back that a thrust vectoring engine with serrated petals was displayed in a factory in the Su-57/PAKFA thread.
At the time, there was confusion, as it was agreed that this wasn't the engine that was to be the final choice for the Su-57..the izd.30.

Does anyone else recall that?

I wonder if this is the platform that engine was targeted at?

Could be that Salyut was aiming for Checkmate with that mystery engine, the fact that Sukhoi ultimately chose Saturn once more not withstanding. This is of course a rational decision from a commonality point of view, but unless it gets Izd. 30 it would leave the aircraft with an increasingly obsolete engine. Salyut's 15.5tf AL-31FM3, with its essentially wholesale replacement of legacy turbomachinery (3-stage blisk LPC, 6-stage HPC) and temperature increase to >1800K, would otherwise be the preferable option.

edit: Top view looks super sleek.

The camera lens plays a role here too, but in aircraft with this kind of fuselage configuration plan view is often the most flattering angle. Even the X-32 looked pretty good from above!

 

[Acatomic]

This EOTS annoying me more and more. Unnecessary, costly and affecting landing gear.

The way I understood yesterday's presentation is that the price of $25-$30 million is for a base configuration.

So if you don't need EOTS then you just don't buy it.

Better?


Like a lot of things that came from Su-57 I believe EOTS also came from somewhere / another program.
My bet is it came from S-70 Okhotnik:

 

[DWG]

This EOTS annoying me more and more. Unnecessary, costly and affecting landing gear.

OTOH, if you want to challenge the F-35 in the export market, it's probably essential. The inlet design is going to make positioning more difficult than for side-intake designs, but I can't help thinking that you could have put them inline with EOTS ahead of gear and still worked the internals of both into the split ducting.

Incidentally it just struck me that the IRST ball is still off-centreline, and we're now two design generations on from the Su-27 variants where it had to be moved off the centreline to create space for the refuelling probe.

 

[Trident]

Two other thoughts that have occurred to me: first, in the same way as the 5 AAM load (implying 3 MRAAMs in the main bay) has implications that read across back to the Su-57, so could the internal laser designator. Second, if this thing hits Mach 1.8 - 2.0 with a fixed intake and the same engine, might that indicate that there is something to the rumours of the Su-57 with its variable intakes being *very* fast indeed? Or at least, that it supercruises extremely fast, if its top speed isn't far in excess of Mach 2.0 (think Concorde, where supercruise was essentially the same as top speed, limited by materials).

 

[DWG]

So, as jeffb mentions, we could potentially have commonality in forward fuselage & cockpit (including equipment & avionics), wings, fins, main weapons bay, landing gear and engine. It's stunning to contemplate that such a high proportion of primary structure from an aircraft *twice* the size could come together into a coherent and even fairly elegant design! I can't think of a recent example that would quite match this feat

I'm not sure re-use is quite that extensive, but there's the reported sourcing of the Su-27IB/Su-34 nose from izdeliye 54 as a precedent https://www.secretprojects.co.uk/th...s-izdelije-54-tactical-bombers.419/post-81820

And of course there's the Fisher P-75....

ETA: and EAP used a Tornado aft-fuselage and fin (which is why Typhoon has a single tail rather than the initially planned twin-tail) and the RB199. Though that was due to German funding shenanigans which meant MBB dropped out of building a composite aft fuselage, rather than being a design choice. In fact it was initially assumed the first 20 (or more?) Eurofighters would have RB199s, but EJ200 completed development early enough that wasn't needed.

 

[FighterJock]

The EOTS is annoying me as well, why design the plane with the landing gear to of-Center like the Su-25. Sukhoi Should have put the EOTS system to the rear of the radar without affecting the landing gear. I hope that come the full production variant Sukhoi gets this sorted out.

 

[Ainen]

Sukhoi Should have put the EOTS system to the rear of the radar without affecting the landing gear. I hope that come the full production variant Sukhoi gets this sorted out.

Space in the nose is limited. It's already very long as it is.

 

[Trident]

I'n bit sure re-use is quite that extensive, but there's the reported sourcing of the Su-27IB/Su-34 nose from izdeliye 54 as a precedent

That's actually a pretty good example that I admittedly hadn't considered, but falls far short of the scale seen here and of course only the Su-34 ever saw the light of day. While we're at it, the same forward fuselage also found its way onto MiG's Izd. 7.01 interceptor, which of course makes it notable for actually crossing the OKB boundary.

And of course there's the Fisher P-75....

"recent" Else various WWII or Korean War Twins/Zwillings come to mind. Although that brings us onto the Stratolaunch Roc, with its extensive reuse of 747 components (cockpit section, landing gear, engines, various avionics and equipment). But even that doesn't quite match Checkmate/Su-57, and of course is a one-off. It's also not what I'd call elegant

ETA: and EAP used a Tornado aft-fuselage and fin (which is why Typhoon has a single tail rather than the initially planned twin-tail) and the RB199. Though that was due to German funding shenanigans which meant MBB dropped out of building a composite aft fuselage, rather than being a design choice. In fact it was initially assumed the first 20 (or more?) Eurofighters would have RB199s, but EJ200 completed development early enough that wasn't needed.

Tornado and EAP/Typhoon are pretty similar in size though, and as you note it was only an improvised solution for a one-off demonstrator, not intended for mass production.

The EOTS is annoying me as well, why design the plane with the landing gear to of-Center like the Su-25. Sukhoi Should have put the EOTS system to the rear of the radar without affecting the landing gear. I hope that come the full production variant Sukhoi gets this sorted out.

It does kind of insult your sense of aesthetics, but I'll cut it some slack for recalling the ultra-cool XF8U-3

 

[FighterJock]

Sukhoi Should have put the EOTS system to the rear of the radar without affecting the landing gear. I hope that come the full production variant Sukhoi gets this sorted out.

Space in the nose is limited. It's already very long as it is.

Sukhoi should have made the fighter a little bit longer to start with and no one would know the difference.

 

[Firefinder]

Sukhoi Should have put the EOTS system to the rear of the radar without affecting the landing gear. I hope that come the full production variant Sukhoi gets this sorted out.

Space in the nose is limited. It's already very long as it is.

Sukhoi should have made the fighter a little bit longer to start with and no one would know the difference.

So long as it doesnt effect landing or ground rolling performance it unlikely to be an issue. People can live with the slight off work.

 

[tequilashooter]

Wish I somehow managed to fool Sukhoi in that airshow that I am some kind of foreign official that is interested in buying it. I am sure they are given more exclusive content on the aircraft like modules used for EW system, radar being used, additional features on aircraft that we currently dont get info on in this forum. Some customers blow their money on things like nothing on products and some customers would like to know more details on what their purchasing and considering there are only money tight customers that the U.S. can barely give a shit about sanctioning they need more details before making purchases. I doubt any user here with the info disclosed now would say shut up and take my money on wanting to purchase this so the sales might be low or if any at all.

 

[stealthflanker]

Su-25 live happily with offset nose landing gear too BTW.

 

[BLACK_MAMBA]

ETA: and EAP used a Tornado aft-fuselage and fin (which is why Typhoon has a single tail rather than the initially planned twin-tail) and the RB199.

The choice wasn't made because they used a Tornado rear fuselage. BAe did studies regarding the two options and found no massive difference that favoured one over the other. MBB wanted two tails though due to their high-alpha "obsession" and as they were to build the rear fuselage so twin tails was selected. When funding etc was pulled and they couldn't do the rear fuselage BAe went with a Tornado single tail which worked well enough. Later they revisited the subject before Typhoon finilisation and decided on a single tail due to the twins offering no real major advantage but requiring a more complex and heavier structure, higher drag etc. EAP might have helped prove the concept, but they didn't go with the single tail just because the EAP had one. The idea was around before then

 

[Manuducati]

The EOTS is annoying me as well, why design the plane with the landing gear to of-Center like the Su-25. Sukhoi Should have put the EOTS system to the rear of the radar without affecting the landing gear. I hope that come the full production variant Sukhoi gets this sorted out.

Then it would probably affect the airflow to the engine, due to the diverterless design.

 

[TR1]

 

[TomcatViP]

Very bad. This is not what we were given to see yesterday.

 

[Archibald]

So, as jeffb mentions, we could potentially have commonality in forward fuselage & cockpit (including equipment & avionics), wings, fins, main weapons bay, landing gear and engine. It's stunning to contemplate that such a high proportion of primary structure from an aircraft *twice* the size could come together into a coherent and even fairly elegant design! I can't think of a recent example that would quite match this feat

I'm not sure re-use is quite that extensive, but there's the reported sourcing of the Su-27IB/Su-34 nose from izdeliye 54 as a precedent https://www.secretprojects.co.uk/th...s-izdelije-54-tactical-bombers.419/post-81820

And of course there's the Fisher P-75....

ETA: and EAP used a Tornado aft-fuselage and fin (which is why Typhoon has a single tail rather than the initially planned twin-tail) and the RB199. Though that was due to German funding shenanigans which meant MBB dropped out of building a composite aft fuselage, rather than being a design choice. In fact it was initially assumed the first 20 (or more?) Eurofighters would have RB199s, but EJ200 completed development early enough that wasn't needed.

Waaaait... the Su-34 nose comes from a late development of the T-4 ? That's amazing. Missed that on this forum back then. Thank you !

 

[Archibald]

Su-25 live happily with offset nose landing gear too BTW.

So does the Whartog, for that matter: GAU-8 didn't left much room in the nose centerline... so the nose wheel went to the side. I only realized this when building the Italeri 1/72 in 1998... still have it.

 

[Dr.Snufflebug]

The landing gear offset has negligible effect on weight and balance.

I take it the in-flight pic with the Su-57 is a photoshop?

It's gonna put a dent in several figures, when things add up, I mean, if there is a slight "skew" that has to be compensated for by the FCS or so, inducing a tiny bit of drag...

There probably isn't an imbalance though, my guess is that they thought of it. Just how is the question, the EOTS itself probably doesn't do it on its own.

Where was the "sidebay gun" supposed to go? Starboard or port? Is it a self-contained unit, or could there be an internal magazine available for that configuation?

Just throwing things out there...

 

[TomcatViP]

Honestly the impact is very minor. See how any plane can land back with assymmetrical ordonnances.

The only slight annoying effect for the pilot is on the ground with more tyre drag on one side.

 

[Dr.Snufflebug]

Honestly the impact is very minor. See how any plane can land back with assymmetrical ordonnances.

The only slight annoying effect for the pilot is on the ground with more tyre drag on one side.

Occasional asymmetrical ordnance is one thing, built-in asymmetry another. The Su-25 was mentioned, but it has a huge offset gun that warrants it, balances it out neatly.

The Sea Vixen had its entire cockpit off-axis, because putting the WSO/radar guy in tandem was impractical. He had to have his dark lair somewhere, and the inlet ducts etc were in the way behind the cockpit. So a side-by-side solution was the way to go. It was balanced.

Other visually asymmetric designs were in fact carefully balanced as well, the crazy Arados spring to mind. Or some of Burts creations.

So my question was, and remains, what balances it out?

 

[overscan (PaulMM)]

ETA: and EAP used a Tornado aft-fuselage and fin (which is why Typhoon has a single tail rather than the initially planned twin-tail) and the RB199.

The choice wasn't made because they used a Tornado rear fuselage. BAe did studies regarding the two options and found massive difference that favoured one over the other. MBB wanted two tails though due to their high-alpha "obsession" and as they were to build the rear fuselage so twin tails was selected. When funding etc was pulled and they couldn't do the rear fuselage BAe went with a Tornado single tail which worked well enough. Later they revisited the subject before Typhoon finilisation and decided on a single tail due to the twins offering no real major advantage but requiring a more complex and heavier structure, higher drag etc. EAP might have helped prove the concept, but they didn't go with the single tail just because the EAP had one. The idea was around before then

Like everything its a tradeoff. There was no "massive difference". Twin tails weighed a bit more, and required much more careful positioning with respect to vortices etc. Whether you believed it was a worthwhile trade depended on how important low speed high-alpha was to you. BAE was not convinced it was worth the weight. MBB was. The choice was reexamined after EAP and BAE won the argument again. With different requirements the choice could have gone the other way. The Typhoon is more akin to the F-16 than the F-18 (optimised for higher speed agility and low energy bleed).

Back to Checkmate. I'm not sure why people are so concerned about the offset nose gear?

 

[flanker]

It has a refuelling probe:

LMAO, that's the original refueling probe from T-50 which was changed on later airframes. Did they outright cannibalized some of old ground airframes of T-50 to make this thing?!

vs

Yeah, it's looking more and more like they have used a lot. I think the Radome on the new aircraft is at least made in the same way as the one in this picture - you can see the fore-aft triangular section shapes in the moulding.

Take a look at the right hand high res image in this post:

https://www.secretprojects.co.uk/threads/sukhoi-lts-checkmate.37538/post-471176

As soon as i saw the profile of the radome and the general shape i got reminded of this infamous radome on T-50S2. I do wonder if it is *exactly* the one... Looks awfully close indeed.

 

[BLACK_MAMBA]

As soon as i saw the profile of the radome and the general shape i got reminded of this infamous radome on T-50S2. I do wonder if it is *exactly* the one... Looks awfully close indeed.

I don't think consensus was reached at the time either. That radome disappeared the moment we saw pictures of the completed airframe where it was fitted with one that has the sharp edges you would expect and as was fitted to the prototypes. It must be some sort of temporary part to cover, add weight or dimensions although a reasoning for it escapes me.

It does however add to the conclusion that this mock-up was clearly built using Su-57 prototype/structural test airframe spares.