Sukhoi T-75 LTS (CheckMate)

[blaze016]

@VTOLicious and @Avimimus
Don't forget that the tail configuration acts as an ejector, drawing a mass flow of air thanks to the nozzle output. So those little trim/elevons are fed with enough airstream in cruise configuration and may even act in-lieu of thrust vectoring.

I was thinking much the same, but also wondering whether thrust vectoring responds fast enough, precisely enough for stabilising an unstable aircraft, as opposed to being used to drive deliberate change in pitch/roll/yaw, which isn't nearly as time sensitive. Anyone know the answer from existing thrust vectoring designs?

Absolutely, on this video, both at the beginning of the video (about 5 seconds in) and between 45 seconds and 1 minute you can see two types of thrust vectoring nozzles work quickly

That doesn't actually answer the question. If you watch the first couple of seconds of the video you'll see the Flanker's horizontal tails moving twice as fast in pitch as the nozzle can. It's almost a case of if you can see it move it's too slow. The FCS is assessing what to do to stop the aircraft departing due to instability on processing cycles of probably around 10ms. This is faster than a human pilot can process, and you need to have the controls respond just as fast as the FCS. We're talking very small, fast twitches of the controls on top of any manouevre being commanded.

And right after that, the shot from a camera placed between the engines looking at the nozzles, pay close attention to the way the nozzles move before the pilot stops the roll, they seem to be doing pretty quick and small movements. Maybe not quite like what you're saying, but I guess that depends on how much they need to deflect in order to keep everything nice and tidy. Then again that kind of "full nozzle" TVC is fairly slow through the entire range of motion. The other type that only moves the petals seems to be much faster, look at the 0:44 mark. Looks fast enough to me. But it doesn't seem that any of the engines that the LTS may use actually have that type of TVC. It looks like izdeliye 30 was planned to use the petal TVC but the (I think) real engine seems to use the "full nozzle" type.

I do doubt the feasibility of using thrust vectoring for control, and looking at it again you could be right. We'll see in 2023 I guess, I don't think this will be the design that flies anyway.

 

[VTOLicious]

Hmm, that aerodynamic layout still puzzles me.

The absence of horizontal tails in combination with those relatively little canted vertical tails is quite unique. I cannot recall any configuration out there with a comaprable wing / control surface layout. Even if those (presumably) split air brakes act as control surfaces as well I cannot imagine they would provide the same pitch control authority as full sized horizontal tails. Would it be viable without thrust vectoring?

Any thoughts?

X-32? It also relied on TVC. In comparison Checkmate actually has more pitch control potential, the fins are all-moving and it has the small trimmers that the X-32 lacks altogether. Could be all it takes in absence of a requirement to land on carriers (which is what drove the adoption of a h-stab in the F-32, IIRC).

I wouldn't claim X-32 was reliant on TVC. It had a highly swept delta wing with very large trailing edge control surfaces and huge ruddervators...
Anyways, imho CheckMate is quite different. The planform is actually closer to the proposed F-32, but without tailplanes!

 

[TMA1]

I have seen the videos where it looks like there is delay between the nozzles and horizontal slabs. I have also seen the airshow clips where you can clearly see the thrust vectoring working, particularly when the jet tail slides. I think they know the capabilities of this craft. It might be too early to dismiss TV as major factor of control in this new fighter.

 

[Trident]

Hmm, that aerodynamic layout still puzzles me.

The absence of horizontal tails in combination with those relatively little canted vertical tails is quite unique. I cannot recall any configuration out there with a comaprable wing / control surface layout. Even if those (presumably) split air brakes act as control surfaces as well I cannot imagine they would provide the same pitch control authority as full sized horizontal tails. Would it be viable without thrust vectoring?

Any thoughts?

X-32? It also relied on TVC. In comparison Checkmate actually has more pitch control potential, the fins are all-moving and it has the small trimmers that the X-32 lacks altogether. Could be all it takes in absence of a requirement to land on carriers (which is what drove the adoption of a h-stab in the F-32, IIRC).

I wouldn't claim X-32 was reliant on TVC. It had a highly swept delta wing with very large trailing edge control surfaces and huge ruddervators...
Anyways, imho CheckMate is quite different. The planform is actually closer to the proposed F-32, but without tailplanes!

Not really reliant, it is more like a Mirage-style tailless delta, true (with TVC as a "bonus"). However, as I said, Checkmate does have everything the X-32 has, plus all-moving fins (likely providing greater pitch control power than the rudders on the X-32) and rudimentary elevators. Or stated differently, while the elevators are smaller than the tailerons on the F-32, it has all-moving fins and possibly a less demanding pitch authority requirement to begin with (carrier ops). Either way it seems like a credible scheme to me.

Maybe LM found a way to combine both LWIR and MWIR:

Dual-band sensors exist (PIRATE for instance has LWIR for search and MWIR for identification), but I'm pretty sure EOTS is not one of them. It's mainly (MWIR-based) hardware re-packaged from the Sniper XR pod and with the software expanded to include an IRST function. And even with a dual-band sensor, the trade-off regarding the installed position of a unified system always remains.

 

[LMFS]

Supercruise 1,8 M? Range without external tanks 2900 km? It's magic plane?

No, just the magic of journalism

1.8 M is the max overall speed, someone probably just made a mistake there. As to the range, the plane is huge and should be able to carry A LOT of fuel, seems totally credible to me.

I wouldn't claim X-32 was reliant on TVC. It had a highly swept delta wing with very large trailing edge control surfaces and huge ruddervators...
Anyways, imho CheckMate is quite different. The planform is actually closer to the proposed F-32, but without tailplanes!

Agree. Still don't understand why some people are talking about the LTS as a delta wing... the wing is the same trapezoid shaped one of the Su-57 and the position re. CoG is also similar, why would it work as a delta wing, with elevons and all that? The plane just has an "unconventional" tail.

 

[XaHyMaH]

Hmm, that aerodynamic layout still puzzles me.

The absence of horizontal tails in combination with those relatively little canted vertical tails is quite unique. I cannot recall any configuration out there with a comaprable wing / control surface layout. Even if those (presumably) split air brakes act as control surfaces as well I cannot imagine they would provide the same pitch control authority as full sized horizontal tails. Would it be viable without thrust vectoring?

Any thoughts?

Those 'things' will be assisted by V-Tail and whole tail is a https://en.wikipedia.org/wiki/Pelikan_tail

And one more crazy theory.
While T-75 is surely a normal aerodynamic scheme, it's centerbody may have an S-shape foil and act as tailless scheme with elevons.

 

[Manuducati]

Hmm, that aerodynamic layout still puzzles me.

The absence of horizontal tails in combination with those relatively little canted vertical tails is quite unique. I cannot recall any configuration out there with a comaprable wing / control surface layout. Even if those (presumably) split air brakes act as control surfaces as well I cannot imagine they would provide the same pitch control authority as full sized horizontal tails. Would it be viable without thrust vectoring?

Any thoughts?

Those 'things' will be assisted by V-Tail and whole tail is a https://en.wikipedia.org/wiki/Pelikan_tail

And one more crazy theory.
While T-75 is surely a normal aerodynamic scheme, it's centerbody may have an S-shape foil and act as tailless scheme with elevons.

The closest match I can think of in therm of general aerodynamic configuration is the early 90's Northrop proposal for the MRF (MultiRole Fighter) program.

 

[Jackonicko]

@paralay
May this help refine the model?

View attachment 661464

This certainly seems to show that many of the drawings out there show tailfins that are too tall.

 

[XaHyMaH]

BTW. Jocker has a Lambda LERX

https://findpatent.ru/patent/184/1840518.html

 

[Geo]

A very informative article about modern Russian turbofans, including options for new Sukhois. In Russian.
https://silovik.org/советское-наследство-турбореактивн/

 

[VTOLicious]

Hmm, that aerodynamic layout still puzzles me.

The absence of horizontal tails in combination with those relatively little canted vertical tails is quite unique. I cannot recall any configuration out there with a comaprable wing / control surface layout. Even if those (presumably) split air brakes act as control surfaces as well I cannot imagine they would provide the same pitch control authority as full sized horizontal tails. Would it be viable without thrust vectoring?

Any thoughts?

Those 'things' will be assisted by V-Tail and whole tail is a https://en.wikipedia.org/wiki/Pelikan_tail

A Pelikan Tail is actually different:
https://www.secretprojects.co.uk/threads/boeing-jast-jsf-x-32-projects.2121/post-18031

...and let's not forget: Up to date no one officially confirmed that those "things" are indeed control surfaces, airbrakes, a combination of both...?

 

[flateric]

A very informative article about modern Russian turbofans, including options for new Sukhois. In Russian.
https://silovik.org/советское-наследство-турбореактивн/

In short - schoolboy takes YF120 performance chart from waybackmachine and describes how good it would be for NGAD.

 

[kaiserbill]

In short - schoolboy takes YF120 performance chart from waybackmachine and describes how good it would be for NGAD.

I agree with you on the comparative nature of the article, but I am quite interested in that model exhibited by Soyuz last year (2020) shown in the article.

I guess my question is... is Soyuz actively working on a developed model of the R79 engine?

 

[Anduriel]

In short - schoolboy takes YF120 performance chart from waybackmachine and describes how good it would be for NGAD.

I agree with you on the comparative nature of the article, but I am quite interested in that model exhibited by Soyuz last year (2020) shown in the article.

I guess my question is... is Soyuz actively working on a developed model of the R79 engine?

There were mention of R119-300 engine developed from R79 for Sukhoi aircraft. What are these precisely is unknown, both for aircraft and engine.

 

[Avimimus]

I wonder if they are still quietly working on getting that done, or whether all resources are directed to the stated MiG-31 replacement?

http://www.promweekly.ru/archive/kret/2021/KRET_3-2021.pdf
KRET seems to still be a firm believer

However, the theory of "pairing" does not work here, because there is a third machine - the super heavy MiG-31. A welded airframe made of steel (they are not made abroad) and a pair of powerful D-30F6 engines (unique in their aggregate characteristics) allow this interceptor to maintain a speed record among consumers - over 3000 km / h. To replace the MiG-31, an even faster MiG-41 is being developed, capable of speeds 4-4.3 times higher than the sound one. At the same time, judging by the statements of the UAC representatives, the corporation is determined to continue the development of light fighters as well.

I will probably have to wait a few days to a week later after the airshow for more new articles from promweekly.ru

The fuel costs... given their difficulty funding training hours historically for the Mig-31 more speed sounds like a questionable choice regarding specifications - unless it is intended to have most of them stay on the ground more often and use the speed to get on station faster (instead of patrolling) - something more like a SAM with a crew...

I could easily see (after checkmate) a lengthened Su-57 with more internal fuel and modified outer wings filling the Mig-31 role though (albeit it would be slower than the existing Mig-31 or even the Su-57 - unless they used new engines).

@VTOLicious and @Avimimus
Don't forget that the tail configuration acts as an ejector, drawing a mass flow of air thanks to the nozzle output. So those little trim/elevons are fed with enough airstream in cruise configuration and may even act in-lieu of thrust vectoring.

Then it's a deltas wing and the V-tail are also sur-elevated, what contributes to the pitch moment.

Interesting... hadn't thought of interactions with the airflow out of the engine! There is still the issue of what happens if there is an engine failure though.

 

[flateric]

I guess my question is... is Soyuz actively working on a developed model of the R79 engine?

From Soyuz 2020 annual report

Earnings - 3.78MUSD

The payroll of all employees of JSC AMNTK Soyuz as of 01.01.2020 amounted to 124 people, including:
- managers - 18 people, which is 14.5% of the total number. - specialists - 53 people or 42.7% of the total number - 11 employees - people or 8.9% of the total number
- auxiliary workers - 42 people or 33.9% of the total number
The number of men working at the enterprise was 107 people - 86.3% of the total number, women - 17 people or 13.7%.
110 people were admitted during the year.
The average number of all personnel in 2020 was 29 people, including 5 women.

Go figure yourself if that pitful shadow of Soviet engine maker living mostly by lease of property they got as inhertance is gonna produce something beyond laser printer made ignorant exhibition brochures.

 

[kaiserbill]

Thanks, but they are just a design bureau, not manufacturer I suppose. Their designs are produced elsewhere. The setup is a bit different to us used to a western combined engine designer and manufacturer I guess.
Is the R79 design property of Soyuz, or the State?
Is there a reason Soyuz is not part of the United Engine Company (UEC)?
Sorry for the questions, but it's interesting to outsiders.

 

[LMFS]

The closest match I can think of in therm of general aerodynamic configuration is the early 90's Northrop proposal for the MRF (MultiRole Fighter) program.

I would think this is essentially a MFI without canards. Now planes are unstable and TVC is fully developed, those canards would (maybe) be a plus for maneuverability and supersonic flight, but not mandatory as they would have been in the past.

BTW. Jocker has a Lambda LERX

Like MiG izd. 33

 

[JSTCVW09CD]

Thanks, but they are just a design bureau, not manufacturer I suppose. Their designs are produced elsewhere. The setup is a bit different to us used to a western combined engine designer and manufacturer I guess.
Is the R79 design property of Soyuz, or the State?
Is there a reason Soyuz is not part of the United Engine Company (UEC)?
Sorry for the questions, but it's interesting to outsiders.

Now it is a private firm and in 1990s, it was divided into 2 parts- one is design firm and the other is engine testing facility.

 

[XaHyMaH]

A Pelikan Tail is actually different:
https://www.secretprojects.co.uk/threads/boeing-jast-jsf-x-32-projects.2121/post-18031

Aerodynamically it's the same - a combination of horizontal and slanted control surfaces.

...and let's not forget: Up to date no one officially confirmed that those "things" are indeed control surfaces, airbrakes, a combination of both...?

If it looks like elevon, placed like elevon - it's probably an elevon ))

 

[VTOLicious]

A Pelikan Tail is actually different:
https://www.secretprojects.co.uk/threads/boeing-jast-jsf-x-32-projects.2121/post-18031

Aerodynamically it's the same - a combination of horizontal and slanted control surfaces.

...and let's not forget: Up to date no one officially confirmed that those "things" are indeed control surfaces, airbrakes, a combination of both...?

If it looks like elevon, placed like elevon - it's probably an elevon ))

Nope.
Time will tell.

 

[citizensnip]

 

[helmutkohl]

ooh very nice!
its like a modern day, stealthy, F-8 Crusader!! and we all love the crusader! in that dark grey-blue color, it reminds me of the French navy F-8s.

in any case how likely is this aircraft able to be navalized? is there enough room for a tail hook in the back?

 

[Scar]

© CRAS from Paralay forum

 

[helmutkohl]

lol glad they went with a Su-9 intake rather than a MiG-21. keep it within sukhoi!

 

[Anduriel]

lol glad they went with a Su-9 intake rather than a MiG-21. keep it within sukhoi!

That is actually MiG-21's intake too...

 

[helmutkohl]

lol glad they went with a Su-9 intake rather than a MiG-21. keep it within sukhoi!

That is actually MiG-21's intake too...

the radome looks a bit smaller no? unless its an early version of the mig-21

 

[Hydroman]

© CRAS from Paralay forum
View attachment 661562

Very nice, the joys of Photoshop.

 

[Archibald]

ooh very nice!
its like a modern day, stealthy, F-8 Crusader!! and we all love the crusader! in that dark grey-blue color, it reminds me of the French navy F-8s.

in any case how likely is this aircraft able to be navalized? is there enough room for a tail hook in the back?

That intake is so weird, tortured - and a split, for only one engine ?

Dead fighter designers from the 50's if they came back would say "that stealth thing may be advantageous, but it really results in ugly and tortured designs..."

 

[DWG]

Thanks, but they are just a design bureau, not manufacturer I suppose. Their designs are produced elsewhere.

To give some perspective,124 is slightly smaller than the team for Eurofighter FCS for most of the time I was on it, and that didn't include QA, HR, corporate management, nor production staff. flateric is right,124 for a design house that needs hardware design, software design (FADEC), advanced metallurgy and in-house prototyping isn't going to cut it.

 

[Avimimus]

A Pelikan Tail is actually different:
https://www.secretprojects.co.uk/threads/boeing-jast-jsf-x-32-projects.2121/post-18031

Aerodynamically it's the same - a combination of horizontal and slanted control surfaces.

Except that it probably isn't - since the elevons can deflect independently. That said, I can definitely see the analogy.

 

[paralay]

Design characteristics of the Fighter-75
weight
maximum 26240 kg
normal 19630 kg - 21220 kg
landing weight 12300 kg
curb weight 11840 kg
empty 11700 kg
of equipment 1290 kg
of airframe with chassis 5790 kg
fuel 7000 kg

load
A-A normal 2 RVV-MD + 3 RVV-SD (790 kg)
A-A maximum 2 RVV-MD + 2 RVV-BD + 4 RVV-SD (2380 kg)
A-S maximum 7400 kg
the range without PTB is 3000 km
the range at cruising supersonic is 1500 km
engine izd.30

It is interesting to deal with the maximum possible load 1. in fast compartments 2 RVV-MD 2 x 110 kg = 220 kg 2. in a huge theoretical maximum of 4 FAB-500 = 2000 kg there are four nodes under the wing, 7400 kg - 2000 kg - 220 kg = 5180 kg
5180 kg : 4 pcs = 1295 kg as an option, MBD3-U2T-1 with two FAB-500 on each

 

[overscan (PaulMM)]

These are Paralay's own estimates not official figures.

 

[Avimimus]

These are Paralay's own estimates not official figures.

Yes... it is important to make that clear, I think - otherwise we'll be seeing them for years!

Every time someone tried to update the Su-57 article to state that it had only one cannon, someone would revert it to say it had two!

 

[Colonial-Marine]

Yes... it is important to make that clear, I think - otherwise we'll be seeing them for years!

Every time someone tried to update the Su-57 article to state that it had only one cannon, someone would revert it to say it had two!

How did that whole myth of the Su-57 having two cannons even come about? From the outset it seemed obvious that it was going to have a single GSh-30-1 like the prior generation of Soviet/Russian fighters.

 

[LMFS]

These are Paralay's own estimates not official figures.

I have my comments to certain values, but in general it should not be too far off and I personally welcome the initiative and the contribution he makes...

 

[DWG]

Russia targets low cost, high performance with Su-75 Checkmate fighter
https://www.flightglobal.com/defenc...m_content=FG-INTERNATIONAL-FILLER-27072021-JM
"UAC chief executive Yuri Slyusar told those assembled that the single-engined jet – which had been earlier revealed as “Project Checkmate” – was “more than just a mock-up”. Instead, it is understood to be an engineering prototype for ground testing, including iron bird and copper bird functions."

"He notes that the name is a deliberate reverse of the digits on Sukhoi’s twin-engined Su-57 stealth fighter"

"His boss, Sergei Chemezov, chief executive of Rostec, says the “flyaway” price of each aircraft will be between $20 million and $30 million. UAC is targeting 300 sales."

"The aircraft will have five internal weapons bays and a weapons load of up to 7.5t."

5?

"it is believed to be considering a variant of the “Item 30” version of the NPO Saturn AL-41F1"

"Mikhail Strelets, the chief designer who heads the project at Sukhoi, says the Su-75 will be equipped with an active electronically scanned array radar capable of tracking 30 targets simultaneously and guiding missiles against six of them."

 

[TMA1]

ooh very nice!
its like a modern day, stealthy, F-8 Crusader!! and we all love the crusader! in that dark grey-blue color, it reminds me of the French navy F-8s.

in any case how likely is this aircraft able to be navalized? is there enough room for a tail hook in the back?

That intake is so weird, tortured - and a split, for only one engine ?

Dead fighter designers from the 50's if they came back would say "that stealth thing may be advantageous, but it really results in ugly and tortured designs..."

Agreed. It's why I am a 30 year old boomer and love the cold war designs. That said at least the ruskies give the boring stealth a bit of flair. Everybody else except China and Russia are making f22 facsimiles. I guess it is nice to see other design ideologies besides the western style still in existence.

Edit: had to correct the autocorrect

 

[LMFS]

"UAC chief executive Yuri Slyusar told those assembled that the single-engined jet – which had been earlier revealed as “Project Checkmate” – was “more than just a mock-up”. Instead, it is understood to be an engineering prototype for ground testing, including iron bird and copper bird functions."

The key here is to watch the aircraft's presentation in Russian and see what they are actually saying... it is just a pity that the captions are not as accurate as we would like to... but regardless, Slyusar pointed clearly at this plane and said it would be the one expected to fly in 2023.

"The aircraft will have five internal weapons bays

3 bays

"it is believed to be considering a variant of the “Item 30” version of the NPO Saturn AL-41F1"

Izd. 30 is not a version of AL-41F-1, and it has not been mentioned for this plane explicitly, I understood Slyusar as saying it was a possibility for the future and that the nozzle was in fact "transitional"... quite interesting, given we have seen it on the display unit of the Su-57E

 

[TMA1]

Is the guy referring to five potential attachment points for the three bays? Wonder if this could mean three attachments for center and one for the two side bays. If so it could potentially imply that su57 could have eight attachment points for A2A loadout as someone had mentioned earlier in this thread.