Sukhoi T-75 LTS (CheckMate)

[Cannonfodder43]

https://twitter.com/x/status/1418513091055206401

View: https://twitter.com/qretaxyeta/status/1418513091055206401?s=19

 

[Mirage4000-5]

T-75

Startet to make a 3D model basing on this

 

[Ainen]

28 t MTOW 23.5 t low estimation MTOW, 12.5+7.5+7.5 = 27.5 t high estimation. Probably 25 t

There is an official number for MTOW, it is 18t.

 

[Acatomic]

"15 to 20 % more power than the F-35's engine" for the future engine.
Do the maths, that's about 49.5k to 51.5k pounds of thrust. Right...
Later of course the power of the new engine is supposed to be 40k lbs. Never mind that's actually less than the F135, but at least it sounds doable.

"16 to 17000 pounds empty weight"
Because typically, a fighters max. weight is double the payload, so empty weight is about max. payload. Right...

But it's only a bit silly, right? Methinks they don't know what they're talking about.

I guess empty weight is somewhere between 10 and 12 tons.

About the engine power.....well, when you put it like that, then numbers don't make sense........or maybe he was talking about specific power?

I don't know what to tell you about the empty weight, he didn't sound too sure about the empty weight, but later on in the video he did mention that the weight is a bit smaller than F-16 (@20:58 mark). He didn't say for which block/version of F-16, or if he meant empty weight or MTOW.

 

[Anduriel]

28 t MTOW 23.5 t low estimation MTOW, 12.5+7.5+7.5 = 27.5 t high estimation. Probably 25 t

There is an official number for MTOW, it is 18t.

There isn't. 18t was from earlier press leaks. Only official data is the one we had seen on presentation.
Plus there was no specification, is it MTOW or normal TOW. TASS said "взлетной массой до 18 тонн"

Источник: Ростех создает однодвигательный легкий сверхзвуковой истребитель-"невидимку"

Самолет будет развивать максимальную скорость полета более 2 махов

tass.ru

 

[Acatomic]

"взлетной массой до 18 тонн" -> takeoff mass up to 18 tons

But yeah, I would also like to see some other source other than that article.

 

[citizensnip]

3d model Sukhoi T-75

 

[Archibald]

Frack, I just had a visual orgasm. Who did that CGI ?

Didn't clicked on the link. Now I'm playing with it like a kid on Christmas day.
You've made my day !

View: https://www.youtube.com/watch?v=V5SF-h0GnBQ

More seriously: the final X-32 shape, if it had won JSF - from this very forum.

https://www.secretprojects.co.uk/attachments/jsf_cv_3view-jpg.17937/

 

[Geo]

3d model Sukhoi T-75

Nice. Thank you.

 

[LMFS]

There is an official number for MTOW, it is 18t.

7.4 t payload + fuel for 3000 km range is already close to 15 t. A light airframe for this size (10 t) + the payload means already 17.5 t... there is no way that is the MTOW, maybe NTOW.

3d model Sukhoi T-75

WOW... now that is a professional model. May you at least share with us some key dimensions you arrived to?

 

[helmutkohl]

There is an official number for MTOW, it is 18t.

7.4 t payload + fuel for 3000 km range is already close to 15 t. A light airframe for this size (10 t) + the payload means already 17.5 t... there is no way that is the MTOW, maybe NTOW.

3d model Sukhoi T-75

WOW... now that is a professional model. May you at least share with us some key dimensions you arrived to?

somewhat random
but how do you feel that until the unveiling.. you had one of the most accurate estimates/model of the next Russian stealth light fighter?
there were like a jillion whatifs from Paralay site, secretprojects, etc. but yours came closest

 

[kaiserbill]

I have seen payload sometimes described as fuel and weapons.
I would personally never use the term like that, and I have seen it used only rarely (as well as the term "useful load"), but there you have it.
Perhaps it's a translation thing?

Normal takeoff is usually the weight of fuel, weapons, and equipment in a normal envisaged role, and will differ between a strike or intercept role.

If we take the general maxim used in the past (I know things change as the decades go by) then the usual, general, rough rule of thumb was maximum weight was roughly double that of empty weight.
I know there have been exceptions to the norm.
Thus, 18t maximum weight implies an empty weight of 8 or 9t.
I doubt this, considering the internal bays and their doors and associated mechanisms, retractable inflight refuelling system, IRST, the inevitable growth of avionics and electronics...etc.

My 2 cents.

 

[kaiserd]

"15 to 20 % more power than the F-35's engine" for the future engine.
Do the maths, that's about 49.5k to 51.5k pounds of thrust. Right...
Later of course the power of the new engine is supposed to be 40k lbs. Never mind that's actually less than the F135, but at least it sounds doable.

"16 to 17000 pounds empty weight"
Because typically, a fighters max. weight is double the payload, so empty weight is about max. payload. Right...

But it's only a bit silly, right? Methinks they don't know what they're talking about.

I guess empty weight is somewhere between 10 and 12 tons.

About the engine power.....well, when you put it like that, then numbers don't make sense........or maybe he was talking about specific power?

I don't know what to tell you about the empty weight, he didn't sound too sure about the empty weight, but later on in the video he did mention that the weight is a bit smaller than F-16 (@20:58 mark). He didn't say for which block/version of F-16, or if he meant empty weight or MTOW.

If this airframe weighs less than an F-16 but has internal bays of the apparent size as stated above then it’s going to have a low fuel fraction, be relatively short range and with probably quite poor range/ payload performance.
That does not appear to be exactly in line with Russian airforce needs or doctrine, which also actually has relatively few aircraft left in need of near term replacement (especially if the Su-57 orders/ deliveries taken into account).
Hence appears it’s the alleged export customer that needs to drive times scales etc. because appears it’s home country won’t actually need or want it for decades.

 

[citizensnip]

 

[paralay]

 

[Archibald]

Oh will you stop this ? I only have one screen to use these pictures as screensavers !

This is aircraft porn ! Christmas in July.

Looking more closely at the intake, it strikes me as a mix of a) X-32 inverted CHIN intake b) F-105 Antonio Ferri's swept-forward side intakes and c) the F-18 LERX
It's amazing, the mix of CFD, stealth and aerodynamics there.

We need a composite word for Ferri-chin-LERX intake !

 

[Mirage4000-5]

3d model Sukhoi T-75

View attachment 661384View attachment 661388View attachment 661386

Were can I find the textures? I bought the model but I can’t open the textures

 

[Avimimus]

I have seen payload sometimes described as fuel and weapons.
I would personally never use the term like that, and I have seen it used only rarely (as well as the term "useful load"), but there you have it.
Perhaps it's a translation thing?

That makes a lot more sense. It gives it allows it to fill its internal weapon bays and gives it just enough fuel to achieve the stated range on internal fuel.

This would mean that external stores (if they are possible) would require a reduction in internal fuel... and drop-tanks would place the aircraft significantly above MTW... an weight creep might end up with a reduction in range.

 

[GARGEAN]

Only time I see payload as different than weapons mass is UAVs. And there payload is weaponry + modular sensor package (usually EOTS). Does anyone have exaplme of payload term including fuel?

 

[LMFS]

I have seen payload sometimes described as fuel and weapons.

I have not seen Russians do that, and in general I think it makes little sense. Fuel + ordnance of 7.4 t is totally mediocre and not something to boast about like UAC did.

Normal takeoff is usually the weight of fuel, weapons, and equipment in a normal envisaged role, and will differ between a strike or intercept role.

I think for the Flanker that was like 50 or 60% fuel and some AAM load. I think the Russians, true to their style, may be misleading us here. Empty weight is a very critical parameter to know from a plane, it allows to take a lot of conclusions about its true capabilities.

somewhat random
but how do you feel that until the unveiling.. you had one of the most accurate estimates/model of the next Russian stealth light fighter?
there were like a jillion whatifs from Paralay site, secretprojects, etc. but yours came closest

Thank you sir. I think that the big bet (a light, single engine fighter with ventral intake and big weapon bays for true multirole capability and big commonality with the Su-57) was proven right and that was a risky call made after thoroughly checking it in the model and against the feeling of the public community at that time, that feels good. Some design solutions like the tail are scarily similar, and the confusion in some media analysing your layout as if it was a real leak is surreal. So it is a very remarkable thing to experience for someone outside of the industry indeed...

 

[Geo]

We want more! And emirati! And vietnamese! And...... :-D

 

[zen]

Is this not needed by Russia?

Historically a lot of aircraft with relatively short range were developed and used by the USSR.

The use of PGMs obviate the need for massive amounts of bombs.

Besides which in non-LO operations with pylon mounted stores...
A fair amount of hardware ought to be lug-able by this design.

Arguably the prevelance of Flanker derivatives is partly a fluke product of timing and politics.

Historically Sukhoi developed quite a few modest ranged single engined aircraft that gave stalwart service to the USSR.

And as I've suggested this might well have been planned for from the beginning. Taking the harder task of the twin engined heavy fighter first knowing a lot of the effort would feed through to smaller single engined fighter.

 

[Avimimus]

I have seen payload sometimes described as fuel and weapons.

I have not seen Russians do that, and in general I think it makes little sense. Fuel + ordnance of 7.4 t is totally mediocre and not something to boast about like UAC did.

That is 41% of MTOW compared to 51% in the F-35A.

The F-35A is about 175% the size of the T-75, but dry weight for system (avionics, crew, etc.) won't be heavier... so I'd be unsurprised if a significant amount of extra empty weight in the T-75 isn't just basic systems weight (under this interpretation).

It is also worth remembering that its basic performance in terms of range and speed is claimed to be pretty equivalent to the F-35A (in spite of being claimed to be much smaller and cheaper to build).

 

[LMFS]

That is 41% of MTOW compared to 51% in the F-35A.

The F-35A is about 175% the size of the T-75, but dry weight for system (avionics, crew, etc.) won't be heavier... so I'd be unsurprised if a significant amount of extra empty weight in the T-75 isn't just basic systems weight (under this interpretation).

It is also worth remembering that its basic performance in terms of range and speed is claimed to be pretty equivalent to the F-35A (in spite of being claimed to be much smaller and cheaper to build).

You can check practically any 4G plane which is significantly smaller and see this does not make sense. For instance F-16, at least 3 m shorter fuselage and significantly smaller overall:
empty 8.5 t, fuel 3.2 t, payload 7.7 t, MTOW 19.2 t. Only the Gripen would be smaller, and it is not even in the same size category of the F-16 (see engine)

3.5 t fuel on a 11 t empty MiG-29 allows 1400 km range, the LTS is not smaller than that and makes 3000 km on internals... definitely 18 t is not MTOW.

 

[alejandro_]

Constructive feedback to Paralay's layout, with great respect and appreciation

> Seems a bit longer than actually is, therefore bays and engine seem smaller in the model than in the reality
> The nose and fuselage in the side view are thicker than in reality
> 5t fuel is probably too low for the 3000 km range in that size of plane
> The aircraft is designed for an AL-31 (izd. 117S, 117, 30) sized engine, not 25 t one.
> The big size of the bay and relatively high payload do not mean the plane needs to be 28 t MTOW. We could build an estimation as follows 10 (empty) +6 (fuel) +7.5 (payload) = 23.5 t low estimation MTOW, 12.5+7.5+7.5 = 27.5 t high estimation. Probably 25 t is a reasonable number. Someone with actual industry experience may say what weight savings a 8 g structure would mean.

Thoughts welcome!

I also thought that perhaps some structural weight was saved by limiting the g factor to 8.

In page 26 paralay provides the percentage of weapons with respecto to MTOW:

F-35А: 31750 – 13290 – 8278 – 100 = 10082 kg, weapons 8165 kg (26%)
F-15E: 211,5 + 91*4 + 431*12 + 2000*2 = 211,5 + 364 + 5172 + 4000 = 9747,5 kg (26.5%)

Similar data for EF-2000, also assuming that pilot weight is 100 Kg:

EF-2000: 23500 - 11000 - 4995 - 100 = 7405 Kg (31.5%)

Now, Dassault likes to boast that Rafale can perform missions carrying a ×1.5 loadout of it's own empty weight:

Rafale: 24500 - 9850 - 4700 - 100 = 9850 Kg (40,2%)

So LTS could potentially be comparable to Rafale.

(*) Rafale, by Andre Breand. ETAI (2019)

 

[Trident]

I have seen payload sometimes described as fuel and weapons.

I have not seen Russians do that, and in general I think it makes little sense. Fuel + ordnance of 7.4 t is totally mediocre and not something to boast about like UAC did.

Only time I see payload as different than weapons mass is UAVs. And there payload is weaponry + modular sensor package (usually EOTS). Does anyone have exaplme of payload term including fuel?

This is an established concept in the industry, but not commonly quoted. The correct terminology would be "useful load", i.e. anything that isn't dead weight, TOW - OEW = useful load = fuel + payload. Payload of course being literally "the load that pays", that weight which it is the aircraft's true mission to transport from A to B, while fuel is merely a facilitator and ultimately a cost: passengers in an airliner, weapons in a combat aircraft etc. This also accounts for the apparent disparity in the definition with UAVs, their task is to carry sensors into position for surveillance, so the ISR equipment counts as payload. Also makes sense in that like weapons in fighters, or cargo in freighters, what is carried varies depending on the objective of a given flight.

The concept of useful load is er... useful because it is indicative of the scope for trading fuel and payload (weapons, in our case) at a given TOW and of how efficient a design is - a large useful load relative to MTOW indicates low OEW.

For a fighter of this size and type, a useful load of 7.4t at a TOW of 18t would be very good, assuming 18t is not the maximum.

 

[Trident]

View attachment 661394View attachment 661395View attachment 661396

Fantastic!

A minor quibble: the cooling air scoops at the base of the fins have a leading edge swept in two planes for edge alignment:

 

[LMFS]

I also thought that perhaps some structural weight was saved by limiting the g factor to 8.

My view is that the plane is actually designed for the izd. 30, but they are not allowed to export it yet, so they are limited to the existing engines izd. 117S to 117, and maybe a new upgraded version with 16 tf. That matches the configurability of the plane and low min price. The 8 g is the element standing out (negatively) in the specs, together with the lack of an internal gun, both consistent with weight reduction, and the 16 tf engine probably the best workaround that they may come up with. If the plane was designed for those engines, they would have probably made it different (smaller, since 3000 km range is a lot of internal fuel) and not get a minus point because of that reduced overload capability. With the VKS it can be different, with an izd. 30 allowing a cannon and a 9 g structure I guess. Far fetched maybe, but IMHO makes a lot of sense, and we will see in the future whether it is right or not.

So LTS could potentially be comparable to Rafale.

It is not only Rafale, it is the same with F-16 for instance. The problem with Paralay's statistic is that it has a 50% error (26% predicted vs 40% real), that is not enough for making predictions. I like the idea and sometimes the method works, but many times it does not. This value cannot be calculated unrelated to the type of airframe, because the errors can be very big.

 

[alejandro_]

It is not only Rafale, it is the same with F-16 for instance.

I did think about the F-16, but then I remember a few years ago it had structural issues due to high loads. I do agree with you that the comparison is tricky, as very often the radio can depend simply on the weapons which are certified rather than the airframe design.

My view is that the plane is actually designed for the izd. 30, but they are not allowed to export it yet, so they are limited to the existing engines izd. 117S to 117, and maybe a new upgraded version with 16 tf.

There are a few candidates. According to Alexey Bulatov, Deputy Chief Designer of LTS, the engine will in the 14.5-16 t class.

Один двигатель и способность поразить шесть целей. Ростех представил истребитель Checkmate

Новейший однодвигательный истребитель поднимется в воздух в 2023 году

tass.ru

Regarding the G limit, it would be interesting to know what are the savings in weight by going from 9 to 8 G.

 

[kaiserbill]

I was going to post, but Trident has eloquently and succinctly explained it above...the term payload, useful load...etc.
Far more eloquently than I would have.

I have no dog in this fight btw, merely making an observation.
I will say though, that I strongly doubt 18t is the maximum takeoff weight of this aircraft. I would imagine it rather to be a typical (undisclosed mission) take off weight.
My opinion only.
Alejandro and LMFS: I had considered the 8g stat being a function of an aggressive weight reduction programme, but I'm not sure the landing gear the designers selected supports that, if you excuse the pun.

 

[Ainen]

smaller, since 3000 km range is a lot of internal fuel

I have serious suspicion that 3000km figure is indeed on internal fuel... with a soft tank in the main bay.

3.5 t fuel on a 11 t empty MiG-29 allows 1400 km range

We have 1 substantially more efficient engine here, on a (likely) much lighter airplane.
+Such short range wasn't the plan for the Mig-29 originally, it was the result of failure to develop necessary composite parts back in the late 1970s. It isn't a problem anymore (certainly not a problem on paper)

 

[Avimimus]

I'd assume that they'd be more interested in how long it can sustain a high gee turn while maintaining supersonic speed, rather than the absolute maximum gee load. For defence against BVR missiles the ability to sustain a turn is usually more important than the sharpness of that turn.

 

[Avimimus]

We have 1 substantially more efficient engine here, on a (likely) much lighter airplane.

+Such short range wasn't the plan for the Mig-29 originally, it was the result of failure to develop necessary composite parts back in the late 1970s. It isn't a problem anymore (certainly not a problem on paper)

Interesting!

 

[tequilashooter]

Is this not needed by Russia?

Historically a lot of aircraft with relatively short range were developed and used by the USSR.

The use of PGMs obviate the need for massive amounts of bombs.

Besides which in non-LO operations with pylon mounted stores...
A fair amount of hardware ought to be lug-able by this design.

Arguably the prevelance of Flanker derivatives is partly a fluke product of timing and politics.

Historically Sukhoi developed quite a few modest ranged single engined aircraft that gave stalwart service to the USSR.

And as I've suggested this might well have been planned for from the beginning. Taking the harder task of the twin engined heavy fighter first knowing a lot of the effort would feed through to smaller single engined fighter.

God I hope and pray that it is not even needed by the Russian's themselves if the modules are hand me down modules from an old 2009 radar. Going after F-35s with these aircrafts would be comparable to Poland doing a cavalry charge on German tanks. The purpose of the aircraft appeals more to export which is great idea since non-western countries have a lot of conflicts with each other.

 

[Trident]

We have 1 substantially more efficient engine here, on a (likely) much lighter airplane.

Not sure that's accurate in subsonic cruise (which is what gets you range), where the high specific thrust for supercruise would hurt propulsive efficiency of the Izd.30. Sure, with higher OPR and turbine inlet temperature, its thermal efficiency will be better, but bypass ratio (where the RD-33 will likely be somewhat higher) has a strong effect - I would expect at best the same cruise SFC.

As for weight, I can't honestly see Checkmate being lighter than 10.5t and it could easily weigh up to 12.5t. So very similar to the MiG-29 instead of much lighter.

+Such short range wasn't the plan for the Mig-29 originally, it was the result of failure to develop necessary composite parts back in the late 1970s. It isn't a problem anymore (certainly not a problem on paper)

Compared to contemporaries such as the Mirage 2000 and F-16 the MiG-29 has at least the same composite content in its structure. And no amount of composite was going to reduce its weight by the 2.5t required to get its fuel fraction with a fuel capacity of 3.5t into a more acceptable ball park. It was simply a kludgy (if admittedly good looking) design.

 

[LMFS]

There are a few candidates. According to Alexey Bulatov, Deputy Chief Designer of LTS, the engine will in the 14.5-16 t class.

Yes, that is what I mean. 117S is 14.5 tf, 117 is 15 tf, the supposed new version of 117 would be 16 tf.

Regarding the G limit, it would be interesting to know what are the savings in weight by going from 9 to 8 G.

Maybe we find some source somewhere... I can imagine the wings and their sustaining structure in the fuselage are very big and have very long force arms, and to increase their resistance against overload can mean a good amount of weight added to the plane.

I will say though, that I strongly doubt 18t is the maximum takeoff weight of this aircraft. I would imagine it rather to be a typical (undisclosed mission) take off weight.

I totally agree

Alejandro and LMFS: I had considered the 8g stat being a function of an aggressive weight reduction programme, but I'm not sure the landing gear the designers selected supports that, if you excuse the pun.

The landing gear and the g tolerance follow different requirements for different operational aspects that can be weighted differently. A beefed-up landing gear is not a huge contribution to weight, but it is critical for the employment of the plane from unprepared bases. Meanwhile, 8 g just means you must be a bit more careful turning.

I have serious suspicion that 3000km figure is indeed on internal fuel... with a soft tank in the main bay.

That would be +1 t fuel max (4.2 x 0.4 x 0.4 x 2 x 0.8). A MiG-29 needs 3.5 t for 1400 km, so this would be ca. 400 km range, making many simplifications.

We have 1 substantially more efficient engine here, on a (likely) much lighter airplane.

AL-31F family and RD-33 are similarly efficient. And how would you support that the plane is much lighter, given its dimensions, bays, equipment etc. We are talking here about a plane making twice as many km per l than the other, not about some 10-20% difference...

I'd assume that they'd be more interested in how long it can sustain a high gee turn while maintaining supersonic speed, rather than the absolute maximum gee load. For defence against BVR missiles the ability to sustain a turn is usually more important than the sharpness of that turn.

The issue is how long does a turn take, so the bigger the overload the better.

@Trident: the izd. 30 is apparently not in the menu for the LTS, at least not in the publicly known export version

 

[kaiserbill]

Alejandro and LMFS: I had considered the 8g stat being a function of an aggressive weight reduction programme, but I'm not sure the landing gear the designers selected supports that, if you excuse the pun.

The landing gear and the g tolerance follow different requirements for different operational aspects that can be weighted differently. A beefed-up landing gear is not a huge contribution to weight, but it is critical for the employment of the plane from unprepared bases. Meanwhile, 8 g just means you must be a bit more careful turning.

I think you misunderstood me.
I, as did Alejandro, wondered whether the stated 8g limit was a function of a very aggressive weight reduction programme.
The undercarriage shows that not to be the case, as do other components that appear to come from the Su-57.

A very aggressive weight reduction programme usually follows a path of every single component being subjected to specific design study, and re-study, to constantly shave weight. It also is likely that each component is specifically designed in a bespoke manner for just that platform, and unlikely to be a modification or re-use of existing components.

The components in question suggest this wasn't such an extreme priority.

The undercarriage has no effect on g obviously, unless the undercarriage is part of an overall strong, over arching weight reduction programme on all components.
So I use that as an indication that this was not a super priority, and that the idle thought I had could be discounted.

 

[Avimimus]

I'd assume that they'd be more interested in how long it can sustain a high gee turn while maintaining supersonic speed, rather than the absolute maximum gee load. For defence against BVR missiles the ability to sustain a turn is usually more important than the sharpness of that turn.

The issue is how long does a turn take, so the bigger the overload the better.

@Trident: the izd. 30 is apparently not in the menu for the LTS, at least not in the publicly known export version

My understanding is that repeated course changes are useful for kinematically defeating missiles (because most AAM/SAM have less average sustained thrust, and bleed energy faster in a turn due to needing a higher angle of attack). Because an aircraft going faster covers a larger distance, any change in course leads to a larger change in lead-course required for the intercepting missile to meet it... and this robs energy from the missile by forcing it to change course repeatedly.

So an aircraft going Mach 1.5 and pulling 8 gees can exhaust a missiles with a peak speed of make 4.5 pulling 20 gees... I recall one interview regarding the PAK-FA requirement stated that sustained supersonic manoeuvrability was a major requirement for defeating surface to air missiles.

So optimal subsonic turn times may actually be much less important these days than energy retention in a turn (in fact, I believe most modern WVR dogfighting techniques also focus on energy retention and position over maximising initial turn rates).

 

[paralay]

It is not only Rafale, it is the same with F-16 for instance. The problem with Paralay's statistic is that it has a 50% error (26% predicted vs 40% real), that is not enough for making predictions. I like the idea and sometimes the method works, but many times it does not. This value cannot be calculated unrelated to the type of airframe, because the errors can be very big.

• MiG-29: 18480 – 10900 – 3240 – 100 = 4240 kg, weapon 2220 kg (12%)
• MiG-35: 23500 – 12100 – 4800 – 100 = 6500 kg (27%)
• F-16: 21772 – 8910 – 3228 – 100 = 9534 kg (43.8% - weapons plus external tanks)
• Rafal: 24500 – 9625 – 4700 – 100 = 10075 kg, weapons 20 Mk82 bombs, 5000 kg (20%), (41% - weapons plus external tanks)
• Typhoon: 21000 – 11000 – 4223 – 100 = 5677 kg (27%)
• F-35A: 31750 – 13290 – 8278 – 100 = 10082 kg, weapons 8165 kg (26%), (32% - weapons plus external tanks, which are not present)
• F-22: 33906 – 19660 – 9367 – 100 = 4779 kg, weapons 2016 kg (6%)

 

[Archibald]

Amazing how the F-35 and Checkmate blueprints overlap...