AMCA - Advanced Medium Combat Aircraft

[Spitfire IX]

So aren't we going to procude a JV engine with Rolls-Royce or Safran for AMCA? news reports that Kaveri R&D has again started to make it better.

Su-57 is a heavy category jet. We parted with Su-57 PAKFA project due to lack of ToT after funding contribution & disagreement on some design aspects. Russia itself has very few Su-57. Future of RuAF is a mystery. They may again target us as a "cash cow". Recently their AL-51 Isdelye-30 engine is making progress so they will give us AL-41 version to upgrade our Su-30MKIs.
Using Su-57 as a stopgap is debatable, but we need AHCA to replace our MKIs. And for that we need good engine for R&D. Either we can make a deal for AL-41 or with USA for engines of their F-15/16 - F110-PW-229, F110-GE-132 (offered on F-16-IN). or we need a JV engine not just for AMCA but for AHCA also.
BTW TFX-Kaan is currently using F110-GE-129.

The search for an engine developer has gone on for years. I would rule out an American OEM for TOT reasons. Even if the OEM agreed to it, that can be halted by the US Congress at any time. That leaves France and UK as possible partners with very advanced technical capability. My impression is that Russia lags far behind.

I imagine that the governments of France and UK would block the transfer of their most advanced technology to another country. I also think that RR and SAFRAN would limit technologies transferred. I presume that TOT is the biggest impediment to reaching agreement on a new engine for AMCA. It could be that India will not accept the limited TOT offered by RR and SAFRAN, making an engine deal with either impossible. Mind you, it was reported that India wanted 100% TOT for GE F414 licence production but accepted a lower level. Perhaps India will end up doing the same with a co-developed engine for AMCA

I have no idea what tech Russia would be prepared to transfer for joint development of an engine.

From what I hear, Turkiye is aiming to develop an engine to replace the GE F110 used in KAAN principally for the purpose of sovereignty. Developing a much more technologically advanced engine is not the primary objective.

 

[Bhartiya Sainik]

The search for an engine developer has gone on for years. I would rule out an American OEM for TOT reasons. Even if the OEM agreed to it, that can be halted by the US Congress at any time. That leaves France and UK as possible partners with very advanced technical capability. My impression is that Russia lags far behind.

I imagine that the governments of France and UK would block the transfer of their most advanced technology to another country. I also think that RR and SAFRAN would limit technologies transferred. I presume that TOT is the biggest impediment to reaching agreement on a new engine for AMCA. It could be that India will not accept the limited TOT offered by RR and SAFRAN, making an engine deal with either impossible. Mind you, it was reported that India wanted 100% TOT for GE F414 licence production but accepted a lower level. Perhaps India will end up doing the same with a co-developed engine for AMCA

I have no idea what tech Russia would be prepared to transfer for joint development of an engine.

From what I hear, Turkiye is aiming to develop an engine to replace the GE F110 used in KAAN principally for the purpose of sovereignty. Developing a much more technologically advanced engine is not the primary objective.

I forgot to ask a querry in any forum till date - Once a country gets a foreign engine as part of an imported jet, there are extra spares also i guess, so cant the scientists & engineers cut it half open & disect everything or unscrew whatever can be unscrewed & then make their own experiment engine ?? Does the engine maker posess the business right to track every engine, where is it, packed or stored, for which jet ??

Also, if Turkey with area 783,000+ sqm & population 86.2 million, can make their own future jet & engine with confidence then why cant we?

 

[Azaad]

The search for an engine developer has gone on for years. I would rule out an American OEM for TOT reasons. Even if the OEM agreed to it, that can be halted by the US Congress at any time. That leaves France and UK as possible partners with very advanced technical capability. My impression is that Russia lags far behind.

I imagine that the governments of France and UK would block the transfer of their most advanced technology to another country. I also think that RR and SAFRAN would limit technologies transferred. I presume that TOT is the biggest impediment to reaching agreement on a new engine for AMCA. It could be that India will not accept the limited TOT offered by RR and SAFRAN, making an engine deal with either impossible. Mind you, it was reported that India wanted 100% TOT for GE F414 licence production but accepted a lower level. Perhaps India will end up doing the same with a co-developed engine for AMCA

I have no idea what tech Russia would be prepared to transfer for joint development of an engine.

From what I hear, Turkiye is aiming to develop an engine to replace the GE F110 used in KAAN principally for the purpose of sovereignty. Developing a much more technologically advanced engine is not the primary objective.

From what I understand SAFRAN has already consented to developing a clean sheet design based on the M-88 core yielding 110-120 KN .

As an aside , they've already run tests on this long ago such that the F-5 upgradation program will also feature a brand new TF based on the same core which just goes to show the envelope to which SAFRAN can expand the M-88 core to.

What this means is it won't take them long to develop such a TF & get it tested for certification. Having said that, the only issue is the cost apart from issues related to IPR ( GoI wants the IPR to be vested with India) & royalty payments. This is Plan A.

Then again with the Kaveri program back on track & 49 KN / 85 KN in terms or Dry & Wet Thrust assured , we won't be surprised if one fine day we learn that GTRE has been tasked to develop a 110-120 KN TF on its own with the possibility of a consultancy to SAFRAN / RR. This is Plan C.

If the 85 KN Kaveri program begins its certification program from 2026 onwards we can be assured of a certification by 2031-32. This in turn means we could go in for an independent 120 KN TF program by 2032 with a date for somewhere in 2045 for final certification. In any case the AMCA Mk-2 isn't expected to be certified before 2040-42.

This may well follow the same path then as all other active 5th Gen FA programs as on date have taken except the F-22 which is to develop a clean sheet design for the TF while going in for a tried & tested one for the certification of the Fighter Aircraft much like what's happening with the Su-57, J-20 & to some extent with the F-35.

Once the FA is certified, newer iterations can fly with the clean sheet TF pending certification post which it'd enter mass production powered by this new clean sheet TF.

There's a certain logic behind what may seem madness today , as 5 th Gen + tech are expected to be powered by ACE / Variable Cycle TFs generating massive power ( I believe the RR TF powering the Tempest / GCAP has the turbine generating 1 MW of power ) .


It makes little sense then for GTRE to tie up with SAFRAN to develop a conventional 120 KN TF spending a king's ransom in the process which in any case the GTRE would master in a decade plus.

In my opinion the negotiations are stuck because we're asking for tech related to the new TF SAFRAN is set to develop for the Franco German FCAS program. That's Plan B. Take this information with a pinch of salt.

 

[Spitfire IX]

I forgot to ask a querry in any forum till date - Once a country gets a foreign engine as part of an imported jet, there are extra spares also i guess, so cant the scientists & engineers cut it half open & disect everything or unscrew whatever can be unscrewed & then make their own experiment engine ?? Does the engine maker posess the business right to track every engine, where is it, packed or stored, for which jet ??

Also, if Turkey with area 783,000+ sqm & population 86.2 million, can make their own future jet & engine with confidence then why cant we?

I believe that China has tried to copy Russian engine designs along the lines you suggest but the copies do not work as well as the original. Certainly if it is unknown why the components of an engine are as they are, taking an engine and its components apart will not teach you how to design a different engine.

Turkey is still a long way from producing a 29,000lb wet thrust engine to replace F110 in KAAN but is moving forwards in stages. It has a 6,000lb engine under test and is working on developing a 10,000lb wet thrust version. It may already have designed a 35,000lb wet thrust engine incorporating lessons learned from other engines developed but its development status is unknown publicly.

Why India could not make the Kaveri engine work, leading to the programme being halted, I do not know but the programme has been revived and could result in a replacement engine for Tejas Mk1A.

 

[Neil (नील/Нил)]

Why do Indian airplane designers consistently go for smaller air intakes when you know that you need more air intake to get more power?

Personally I think the selection of smaller air-intakes on the AMCA has more to do with maintaining the stealth characteristics of the airframe as smaller intake = less portion of the intake's interior components exposed = less RCS = better stealth. And the design is good enough to allow an adequate flow of air through the intakes to power the AMCA's engines, it's not too big nor too small for its intended purpose.

 

[Spitfire IX]

From what I understand SAFRAN has already consented to developing a clean sheet design based on the M-88 core yielding 110-120 KN .

As an aside , they've already run tests on this long ago such that the F-5 upgradation program will also feature a brand new TF based on the same core which just goes to show the envelope to which SAFRAN can expand the M-88 core to.


There's a certain logic behind what may seem madness today , as 5 th Gen + tech are expected to be powered by ACE / Variable Cycle TFs generating massive power ( I believe the RR TF powering the Tempest / GCAP has the turbine generating 1 MW of power ) .

It makes little sense then for GTRE to tie up with SAFRAN to develop a conventional 120 KN TF spending a king's ransom in the process which in any case the GTRE would master in a decade plus.

In my opinion the negotiations are stuck because we're asking for tech related to the new TF SAFRAN is set to develop for the Franco German FCAS program. That's Plan B. Take this information with a pinch of salt.

I take your point that it would be a mistake paying SAFRAN $5 billion plus to develop an engine unsuitable for use in a 6G aircraft. In my view it would be better to greatly increase funding to GTRE and to develop a 110kN engine in India - always assuming that GTRE is capable of doing such a thing. If GTRE could not fix the problems in Kaveri and needed SAFRAN to fix them, do they have the expertise required to design and develop a fast jet engine?

 

[Bhartiya Sainik]

Why do Indian airplane designers consistently go for smaller air intakes when you know that you need more air intake to get more power?

Deciding intake size & shape is not so easy. It depends on jet's role, speed required & other design parameters.

More air for more power is just 1 contributing aspect. A jet like MiG-25/31, F-15/22, etc may go beyond Mach 2.5 but inlet cross section area may have to be dynamically controlled as per aircraft speed bcoz airspeed at engine fan intake cannot be supersonic or shockwaves will destroy engine.
Before DSI (Diverterless Supersonic Intake), in some engines, intake ramps were used to reduce supersoic inlet-air speed to subsonic just before reaching fans.

As we see, the ramps reduces cross section & choke the airflow & then when area increases, then air speed decreases.
DSI intake doesn't have any ramps. The bump reduces cross-section & chokes the airflow. There are 2 types of shockwaves which reduce speed of air - Normal & Oblique.


In my limited IQ & knowledge IDK if we have any formula to calculate power & fuel required at any level, given the dimensions (fan intake area, engine length) & weight of engine. Engine thrust/weight ratio & fuel consumption varies. Given any engine with an inlet diameter, it is upto designer how much thrust can be squeezed out. Engineers either do not know that limit or it is above top secret.

The parameters which influence thrust & fuel economy of engine are all of its design parameters & operating conditions -
- Compression or Pressure ratio - how much air can be compressed
- with how many fan, low pressure, high pressure compressor stages.
- Air mass flow per second
- combustor design
- Turbine inlet temperature
- # of high & low pressure turbine stages
- Stator vanes control as per speed
- Afterburner design
- Bypass ratio
- fixed/variable cycle engine

In theory there is a formula F=Ma = M(Vout-Vin) where V is air velocity at intake & exhaust.
But practically, how fast will a jet go depends on
- airframe weight at the time
- engine design
- altitude (air density), friction force.
- airframe design producing certain amount of lift & drag due to friction & shockwaves.
- special feautures like shock compression lift.

2 same jets with different wing & fuselage design but with same # & type of engine(s) will have different performance.

Personally I think the selection of smaller air-intakes on the AMCA has more to do with maintaining the stealth characteristics of the airframe as smaller intake = less portion of the intake's interior components exposed = less RCS = better stealth. And the design is good enough to allow an adequate flow of air through the intakes to power the AMCA's engines, it's not too big nor too small for its intended purpose.

1st the engine, when new, is being tested in open-air, flight test-bed, tunnel & its performance at various throttle positions, altitude, speed is documented.
Then the cross section area of inlet is decided as per intended aircraft with 1 or 2 engines required. Some engines have many variants including export ones with slightly different dry & wet thrust. An engine may have 1 or 2 inlets as per airframe design. Gripen, Tejas MK2(MWF) - 1 engine, 2 inlets. F-18 E/F, TEDBF, AMCA - 2 engines, 2 inlets.
Then stealth treatment like geometric planform shaping, serated edges, etc, are done with testing, IF the jet is stealth. F-18 E/F, KF-21 Boramae, Gripen using F414 engine are not stealth, nor will the TEDBF, Tejas MK2(MWF) but AMCA will be.

 

[Azaad]

I take your point that it would be a mistake paying SAFRAN $5 billion plus to develop an engine unsuitable for use in a 6G aircraft. In my view it would be better to greatly increase funding to GTRE and to develop a 110kN engine in India - always assuming that GTRE is capable of doing such a thing. If GTRE could not fix the problems in Kaveri and needed SAFRAN to fix them, do they have the expertise required to design and develop a fast jet engine?

I reckon either RR or SAFRAN will serve the role of a consultant. After all there's a precedent . Both these entities were consulted at different points in time for different issues during the development of the Kaveri TF.

 

[scholar of war]

I forgot to ask a querry in any forum till date - Once a country gets a foreign engine as part of an imported jet, there are extra spares also i guess, so cant the scientists & engineers cut it half open & disect everything or unscrew whatever can be unscrewed & then make their own experiment engine ?? Does the engine maker posess the business right to track every engine, where is it, packed or stored, for which jet ??

Also, if Turkey with area 783,000+ sqm & population 86.2 million, can make their own future jet & engine with confidence then why cant we?

1)even if we do ebsd, xrd, sem, tem etc or any other techniques we can only find the composition of the material. But to make the engine we also need to find the manufacturing and fabrication techniques.

2) f 110 is a fourth gen engine with thrust to weigt ratio of 7 and turki are planning to make a 4th gen engine replacement while we are planning to make a 5 th gen engine with thrust to weight ratio of more than 9-10.

A hypothetical upscaled Kaveri engine with increased bypass ratio ia far superior to any hypothetical turki engine

 

[scholar of war]

I believe that China has tried to copy Russian engine designs along the lines you suggest but the copies do not work as well as the original. Certainly if it is unknown why the components of an engine are as they are, taking an engine and its components apart will not teach you how to design a different engine.

Turkey is still a long way from producing a 29,000lb wet thrust engine to replace F110 in KAAN but is moving forwards in stages. It has a 6,000lb engine under test and is working on developing a 10,000lb wet thrust version. It may already have designed a 35,000lb wet thrust engine incorporating lessons learned from other engines developed but its development status is unknown publicly.

Why India could not make the Kaveri engine work, leading to the programme being halted, I do not know but the programme has been revived and could result in a replacement engine for Tejas Mk1A.

Turki will easily make an F110 class engine with similar if not slightly worse thrust to weight ratio And slightly increased bypass ratio.

People always read only the thrust value but not the thrust to weight ratio value and bypass ratio value.


Any one can make engine of any thrust capacity but very few countries can make engine with thrust to weight ratio greater than 9.
Furthermore thrust of any engine can be increased by increasing bypass ratio.

F 110 class engine with thrust to weight ratio of 7 and bypass ratio of .7 is a vintage tech at this point, even f 404 is far superior technologically compared to it.

 

[Neil (नील/Нил)]

I expect the AMCA to be equipped with weopons and sensors similar to the ones used on the American F-35 and F-22, I am leaning more towards the F-35 though because even in design and weight category, it is very similar to the F-35 too if a comparison were to be made.

So let's talk about SPEAR-EW.

"SPEAR-EW is a new development which will carry out Suppression of Enemy Air Defence (SEAD) missions. Utilising a next-gen miniature Electronic Warfare payload provides both stand-in jammer and decoy capabilities."

The above is a quote from an MBDA article whose link is shared by me here.

SPEAR-EW | Air Dominance, TACTICAL STRIKE | MBDA

SPEAR-EW Air Dominance, TACTICAL STRIKE NETWORK ENABLED ELECTRONIC WARFARE CAPABILITY | Reduced overall mission costs and through life capability costs

www.mbda-systems.com

So in short, the SPEAR-EW is a stand off jammer, meaning in layman terms, you can think of it as a jammer on a cruise missile/glide kit.

Though in today's modern combat, fighter jets employ jamming tactics to able to suppress threats such as enemy EW, missiles fired by an adversary, the one problem with using jamming is that you can become an easy target for Anti-Radiation missiles, or missiles which can use capabilities such as HOJ mode, for e.g the American AIM-120 has a HOJ mode on it. Using a jammer can easily disclose your location to detection systems which may detect your position by detecting the electromagnetic waves emitted by your Jamming equipment.

And this is where SPEAR-EW can prove to be a game changer.
1. You can use it as a decoy to trick ARMs into changing their direction.
2. With the right materials, a great balance of technology and good economy of scale, you can produce many of these.

If the AMCA is going to be used in SEAD operations then if equipped with a system like SPEAR-EW, it can wreck havoc on enemy air defenses, the way that F-35 would be used in SEAD with SPEAR EW and a stealth missile like SCALP or JSM.

The concept of SPEAR EW is very clear: "A glide kit/cruise missile containing an onboard jammer, basically a stand off jammer, which will be cheap to produce and can be spammed at any enemy ADS to overwhelm it during SEAD ops, can be used for other purposes too".

Concept artwork to illustrate how F-35s and various European fighters would use SPEAR EW.


Fingers Crossed that the authorities at DRDO come up with something like this, I mean it's a very creative concept in my opinion and I am confident that it won't be difficult to make something similar in house to the SPEAR EW with our current technology.

 

[125mm_Smoothbore]

for amca ?

amca's internal weapon bay

 

[Bhartiya Sainik]

1)even if we do ebsd, xrd, sem, tem etc or any other techniques we can only find the composition of the material. But to make the engine we also need to find the manufacturing and fabrication techniques.

Yes that's true otherwise HAL after assembling many foriegn engines would have made many domestic engines by now. I guess we don't try to make even civil engine.

2) f 110 is a fourth gen engine with thrust to weigt ratio of 7 and turki are planning to make a 4th gen engine replacement while we are planning to make a 5 th gen engine with thrust to weight ratio of more than 9-10.
A hypothetical upscaled Kaveri engine with increased bypass ratio ia far superior to any hypothetical turki engine

Turki will easily make an F110 class engine with similar if not slightly worse thrust to weight ratio And slightly increased bypass ratio.
People always read only the thrust value but not the thrust to weight ratio value and bypass ratio value.
Any one can make engine of any thrust capacity but very few countries can make engine with thrust to weight ratio greater than 9.
Furthermore thrust of any engine can be increased by increasing bypass ratio.
F 110 class engine with thrust to weight ratio of 7 and bypass ratio of .7 is a vintage tech at this point, even f 404 is far superior technologically compared to it.

In my limited IQ & knowledge, after looking at publicly available diagrams & specs for numerous civil & military engines, no doubt that every Kg/Lb reduction is like a trophy. But looking at technical evolution & requirements, just looking at engine T/W ratio may be confusing actually. People use it to guess a new engine's properties & capabilities.

Typically, different static & moving parts of engine depending upon their required strength, temperature, pressure, are made of Aluminium, Steel, Titanium.
R&D to reduce weight, increase strength & performace allowed Kevlar, some secret alloys based on Nickel, Cobalt, Iron, Chromium, Yitrium, Tungsten, Molybdenum, Niobium, Tantalum, Zirconium, etc.

But the weight reduction has a limit & upcoming technology of variable cycle engine will add more weight, due to extra bypass sections, extra cooling equipment like heat exchangers, pumps, plumbing, etc.


Also, some engines like F-35's F-135 & f-22's F119 use more stage(s) of fixed exhaust vanes with secret ceramic-stealth alloys blocking the turbine blades & afterburner flame-holders. This reduces rear RCS but again adds weight.


F-22, YF-23, perhaps F-35 too, use "Transpiration cooling" where the nozzle has tiny perforations to induce compressed cooled air, meaning additional cooling equipment, again adding weight.
Google image search 'F-22 nozzle closeup" doesn't give zoom enough, but honeybees sticking to nozzles created news & exposed these cooling holes, LOL!


There is also debate on whether an adjacant component attached to engine should be included in its weight or not like TVC nozzle, cooling system, gearbox, etc.
Some say that only the parts inside the cylindrical body controlling the airflow should be part of weight. Some include external attachments like electronics & sensor boxes, plumbing for air, fuel, oil, coolant.
Some say that whatever engine company delivers, in or out of engine body, is part of weight.
The above 3 logic gives 3 different engine weights.

Different engines have different Afterburner capabilities. People usually consider wet thrust to be roughly 50% of 100% dry thrust, but it can range from 30%-72%. If F-22 dry/wet thrust is considered 116/156 KN then that's just 34% more, it is among the lowest . F-111B's TF-30-P-3, F110-GE-129 & 132 (used on Kaan, F-15/16), RD-93(MiG-29, JF-17) are among highest, produce 71-72% wet thrust.

Dry T/W ratio - MiG-25's R-15B-300 has T/W=3.06; F-22's F119 has 6.67; F-35's F135 has 7.67;
Wet T/W ratio - SEPECAT Jaguar's RRTA-MK2 T/W=4.09; F-22 has 8.97; F-35's F135 has 11.45;
NOTE- Above data for F-22 & F-35 considers their engines F119 to be 1.7 tons reported earlier, but now online data has changed to 2.2 tons for F119 & 2.9 tons for F-135 which will reduce their T/W ratio values.
Dry T/W ratio - F-22's F119 = 5.2; F-35's F135 = 4.47
Wet T/W ratio - F-22's F119 = 7; F-35's F-135 = 6.69

So it becomes difficult to compare engines only by their T/W ratio.

Like i mentioned earlier, the internal makeup of engine parts decide max dry & wet thrust.
NOTE-1 - Speed of air at engine fan intake has to be high sub-sonic.
NOTE 2 - Engine intake diameter can be limitedly increased to increase by-pass ratio. The rotaional speed has to be decreased so that fan-tip's tangential velocity is not supersonic.
NOTE-3 - Bypass air also contributes to thrust significantly, in fact, more than core air. It is not just for fuel-economy. But a military engine obviously cannot have high bypass ratio highly increasing the size of engine itself. plus it may require additional 3rd spool or geared turbofan, adding to weight.
NOTE-4 - Above 3 points means there will be a fixed upper limit on cylindrical volume of air entering the engine & the designer has to compress it max, heat it max & push it out as fast as possible, along with some bypass air.

In the end it is the airframe performance which matters. Total thrust / Airframe weight ratio matters more.

 

[fire starter]

Regarding infrared stealth here is the paper by ADA for active cooling of engine bay and nozzle for stealth aircraft.

Feasibility study of engine bay ventilation with intake air driven by ejector nozzle.


In this approach nozzle of engine will be covered by ejector inlet.

(PDF) Feasibility study of engine bay ventilation with intake air driven by ejector nozzle

PDF | Feasibility study of engine bay ventilation with intake air driven by ejector nozzle Abhijit Dhamanekar, Aishwarjya Gogoi ABSTRACT The present... | Find, read and cite all the research you need on ResearchGate

www.researchgate.net

 

[scholar of war]

Yes that's true otherwise HAL after assembling many foriegn engines would have made many domestic engines by now. I guess we don't try to make even civil engine.




In my limited IQ & knowledge, after looking at publicly available diagrams & specs for numerous civil & military engines, no doubt that every Kg/Lb reduction is like a trophy. But looking at technical evolution & requirements, just looking at engine T/W ratio may be confusing actually. People use it to guess a new engine's properties & capabilities.

Typically, different static & moving parts of engine depending upon their required strength, temperature, pressure, are made of Aluminium, Steel, Titanium.
R&D to reduce weight, increase strength & performace allowed Kevlar, some secret alloys based on Nickel, Cobalt, Iron, Chromium, Yitrium, Tungsten, Molybdenum, Niobium, Tantalum, Zirconium, etc.

But the weight reduction has a limit & upcoming technology of variable cycle engine will add more weight, due to extra bypass sections, extra cooling equipment like heat exchangers, pumps, plumbing, etc.
View attachment 1398

Also, some engines like F-35's F-135 & f-22's F119 use more stage(s) of fixed exhaust vanes with secret ceramic-stealth alloys blocking the turbine blades & afterburner flame-holders. This reduces rear RCS but again adds weight.
View attachment 1399
View attachment 1411
F-22, YF-23, perhaps F-35 too, use "Transpiration cooling" where the nozzle has tiny perforations to induce compressed cooled air, meaning additional cooling equipment, again adding weight.
Google image search 'F-22 nozzle closeup" doesn't give zoom enough, but honeybees sticking to nozzles created news & exposed these cooling holes, LOL!
View attachment 1412

There is also debate on whether an adjacant component attached to engine should be included in its weight or not like TVC nozzle, cooling system, gearbox, etc.
Some say that only the parts inside the cylindrical body controlling the airflow should be part of weight. Some include external attachments like electronics & sensor boxes, plumbing for air, fuel, oil, coolant.
Some say that whatever engine company delivers, in or out of engine body, is part of weight.
The above 3 logic gives 3 different engine weights.

Different engines have different Afterburner capabilities. People usually consider wet thrust to be roughly 50% of 100% dry thrust, but it can range from 30%-72%. If F-22 dry/wet thrust is considered 116/156 KN then that's just 34% more, it is among the lowest . F-111B's TF-30-P-3, F110-GE-129 & 132 (used on Kaan, F-15/16), RD-93(MiG-29, JF-17) are among highest, produce 71-72% wet thrust.

Dry T/W ratio - MiG-25's R-15B-300 has T/W=3.06; F-22's F119 has 6.67; F-35's F135 has 7.67;
Wet T/W ratio - SEPECAT Jaguar's RRTA-MK2 T/W=4.09; F-22 has 8.97; F-35's F135 has 11.45;
NOTE- Above data for F-22 & F-35 considers their engines F119 to be 1.7 tons reported earlier, but now online data has changed to 2.2 tons for F119 & 2.9 tons for F-135 which will reduce their T/W ratio values.
Dry T/W ratio - F-22's F119 = 5.2; F-35's F135 = 4.47
Wet T/W ratio - F-22's F119 = 7; F-35's F-135 = 6.69

So it becomes difficult to compare engines only by their T/W ratio.

Like i mentioned earlier, the internal makeup of engine parts decide max dry & wet thrust.
NOTE-1 - Speed of air at engine fan intake has to be high sub-sonic.
NOTE 2 - Engine intake diameter can be limitedly increased to increase by-pass ratio. The rotaional speed has to be decreased so that fan-tip's tangential velocity is not supersonic.
NOTE-3 - Bypass air also contributes to thrust significantly, in fact, more than core air. It is not just for fuel-economy. But a military engine obviously cannot have high bypass ratio highly increasing the size of engine itself. plus it may require additional 3rd spool or geared turbofan, adding to weight.
NOTE-4 - Above 3 points means there will be a fixed upper limit on cylindrical volume of air entering the engine & the designer has to compress it max, heat it max & push it out as fast as possible, along with some bypass air.

In the end it is the airframe performance which matters. Total thrust / Airframe weight ratio matters more.

Brother, I have also studied Gas Turbine Theory by Cohen and Rogers during my masters so please no need to explain everything from basics, thank you.

I know that all the parameters are interconnected and every engine is designed for specific operation envelope. I also know about engine cooling and variable-cycle engines.

Let's put simply why I am against the focus of thrust values for classifying engines:

1) It only gives info about the class of engine but no idea about the level of the tech behind it, for example, both P&W J58 and R-15 turbojets are 100 KN class engines but they are ancient tech and weigh more than 2.5 times compared to F414(another 100 KN class engine). Similarly, PW 2000 and F135 produce similar levels of thrust but one is a high bypass ratio turbofan for transport applications while the other is a state of the art low bypass turbofan for fighter aircraft.

2) Anyone can make an engine of any thrust value if they are willing to sacrifice weight and fuel efficiency Ex- General Electric GE 4 turbojet was designed to have a humongous thrust of 290 KN was designed in 1960s.

3) There are far more important parameters like turbine inlet temperature (TET) that give actual tech-level info. We also have parameters like specific fuel consumption and T/W ratio.

4) Comparing engines of different by-pass ratios is like comparing apples to oranges, people keep comparing engines like the F-414, EJ 200, M88 etc. with engines like the F-110.


In summary, we should only compare engines of similar by-pass ratios and of similar weight classes otherwise comparing different weight classes or different bypass ratio means nothing.

 

[scholar of war]

So it becomes difficult to compare engines only by their T/W ratio.


In the end it is the airframe performance which matters. Total thrust / Airframe weight ratio matters more.

1) T/W ratio is insufficient but T/W together with bypass ratio value gives a general idea.

2) Airframes are designed around an engine, not the other way around so there should be some metric to compare the engines. Planes with similar trust-to-weight ratios but with different bypass ratio engines will have radically different aerodynamic performance.

3) Airframe performance depends on far more factors than just T/W ratio for example Tu - 160 with a t/w ratio .37 is a supersonic bomber and can remain at supersonic speed for longer durations compared to planes with far better T/W ratio

 

[Bhartiya Sainik]

Brother, I have also studied Gas Turbine Theory by Cohen and Rogers during my masters so please no need to explain everything from basics, thank you.

I know that all the parameters are interconnected and every engine is designed for specific operation envelope. I also know about engine cooling and variable-cycle engines.

Wow! obviously i didn't know that. I am happy to interact with you. Now i can clear a lot of doubts with you. Don't take anyting personal. We all need to interact as if this is a F2F common gathering in our housing society or a formal seminar. I am very simple, ordinary, middle-aged, IT sr.sys.admin., i always hated PCM. Since my middle-school days in mid-1990s i just watched Discovery Channel, did internet search when it came & documented whatever i understood superficially. I'm religious minded, never use slangs. This is a forum, not 1on1 message/email, so everything is for everyone. We won't know anything until something is put here.

Let's put simply why I am against the focus of thrust values for classifying engines:

1) It only gives info about the class of engine but no idea about the level of the tech behind it, for example, both P&W J58 and R-15 turbojets are 100 KN class engines but they are ancient tech and weigh more than 2.5 times compared to F414(another 100 KN class engine). Similarly, PW 2000 and F135 produce similar levels of thrust but one is a high bypass ratio turbofan for transport applications while the other is a state of the art low bypass turbofan for fighter aircraft.

2) Anyone can make an engine of any thrust value if they are willing to sacrifice weight and fuel efficiency Ex- General Electric GE 4 turbojet was designed to have a humongous thrust of 290 KN was designed in 1960s.

3) There are far more important parameters like turbine inlet temperature (TET) that give actual tech-level info. We also have parameters like specific fuel consumption and T/W ratio.

Yes, i already mentioned those in another post.

4) Comparing engines of different by-pass ratios is like comparing apples to oranges, people keep comparing engines like the F-414, EJ 200, M88 etc. with engines like the F-110.
In summary, we should only compare engines of similar by-pass ratios and of similar weight classes otherwise comparing different weight classes or different bypass ratio means nothing.

Well, i agree if the bypass ratios are too different, but the end product is the airframe & we are specifically talking on fighter jets. Engine is just a small important ingredient of airframe.
Ultimately, World thinks about light/medium/heavy jets, not engines. And there is no clear boundary b/w the weight of jets or engines.
F-135 was earlier quoted 1.7 T & now 2.9 T, heaviest among currently operating fighter jets but F-35A(13.3 tons empty) is considered somewhat on medium side.
We consider LCA(6.56 tons empty) as Light using F-404 (1 ton), Tejas MK2 as MWF (7.85 tons empty), but USA considers F-16(8.57-12 tons empty) to be Light( LWF program) using F100-PW-229 or F110-GE-132 engine (1.7-1.8 tons).
So there is clearly no trend that light/medium/heavy engine goes into light/medium/heavy jet respectively. Then why to focus on engine T/W for comparison rather than on the jet T/W?

F 110 class engine with thrust to weight ratio of 7 and bypass ratio of .7 is a vintage tech at this point, even f 404 is far superior technologically compared to it

Ok, could you please elaborate on tech gap b/w F404 & F110? I'm low on the history part, being a civilian ethusiast i focus only on parameters. On Wiki i am reading that 1st variant started testing in 1981, 1st variants used on F-14, later versions -129/-132 used on F-15EX/K/SA/QA/SG, F-16 E/F. FADEC also started in 1970s. F-404 came in 1978, before F110 in 1981. Today every engine is expected to have FADEC, so what does F404 have extra that it makes F110 VINTAGE?

 

[Gutenmorgen]

Isn't the whole CATS programme mainly geared towards this kinda thing only. You can mount jammers, IR, decoys and other radars on expendable assets and 'send ahead' of your manned platforms (connected via a data link) which stay back in relative safety, essentially making them a command and control unit. Medium sized ones will even carry missiles. The unmanned assets can even guide the payload to the target, in theory.

Whats missing is a really long range standoff weapon. Astra mk 3 will give us some of the range but IMO if one is to make this kind of tactic into a doctrine, they should have two stage ammunitions (at least for A2A). The purpose of the first stage would be to just provide range as fast as possible, which can be dropped off after doing its thing, making the rest of the missile/ammunition lighter and as maneuverable as the current ones. The second stage can then function as a normal missile. It will make the payload heavier but doing it on your non expendable heavier manned assets is a lot more achievable than making your unmanned assets heavier and keeping them cheap.
This will help make your manned platfoms stay a lot behind and safe. Ofc, a reliable and safe data link will also be needed.
Without this (again IMHO), you would either have to depend on payloads carried by your unmanned assets which will have lower payload capacity due to smaller size, making them shorter in range, OR your manned assets will have to be a lot closer behind, making them more vulnerable to enemy fire.

In my mind, this should be the obvious progression before more reliably autonomous unmanned assets enter service which can be commanded from a ground station and just given missions to execute. For now this remains almost a stuff of sci-fi.

I expect the AMCA to be equipped with weopons and sensors similar to the ones used on the American F-35 and F-22, I am leaning more towards the F-35 though because even in design and weight category, it is very similar to the F-35 too if a comparison were to be made.

So let's talk about SPEAR-EW.

"SPEAR-EW is a new development which will carry out Suppression of Enemy Air Defence (SEAD) missions. Utilising a next-gen miniature Electronic Warfare payload provides both stand-in jammer and decoy capabilities."

The above is a quote from an MBDA article whose link is shared by me here.

SPEAR-EW | Air Dominance, TACTICAL STRIKE | MBDA

SPEAR-EW Air Dominance, TACTICAL STRIKE NETWORK ENABLED ELECTRONIC WARFARE CAPABILITY | Reduced overall mission costs and through life capability costs

www.mbda-systems.com

So in short, the SPEAR-EW is a stand off jammer, meaning in layman terms, you can think of it as a jammer on a cruise missile/glide kit.

Though in today's modern combat, fighter jets employ jamming tactics to able to suppress threats such as enemy EW, missiles fired by an adversary, the one problem with using jamming is that you can become an easy target for Anti-Radiation missiles, or missiles which can use capabilities such as HOJ mode, for e.g the American AIM-120 has a HOJ mode on it. Using a jammer can easily disclose your location to detection systems which may detect your position by detecting the electromagnetic waves emitted by your Jamming equipment.

And this is where SPEAR-EW can prove to be a game changer.
1. You can use it as a decoy to trick ARMs into changing their direction.
2. With the right materials, a great balance of technology and good economy of scale, you can produce many of these.

If the AMCA is going to be used in SEAD operations then if equipped with a system like SPEAR-EW, it can wreck havoc on enemy air defenses, the way that F-35 would be used in SEAD with SPEAR EW and a stealth missile like SCALP or JSM.

The concept of SPEAR EW is very clear: "A glide kit/cruise missile containing an onboard jammer, basically a stand off jammer, which will be cheap to produce and can be spammed at any enemy ADS to overwhelm it during SEAD ops, can be used for other purposes too".

Concept artwork to illustrate how F-35s and various European fighters would use SPEAR EW.
View attachment 1335View attachment 1336

Fingers Crossed that the authorities at DRDO come up with something like this, I mean it's a very creative concept in my opinion and I am confident that it won't be difficult to make something similar in house to the SPEAR EW with our current technology.

 

[Bhartiya Sainik]

1) T/W ratio is insufficient but T/W together with bypass ratio value gives a general idea.

The engines can be compared on not just (T/W ratio + Bypass ratio) but all other parameters.

The parameters which influence thrust & fuel economy of engine are all of its design parameters & operating conditions -
- Compression or Pressure ratio - how much air can be compressed
- with how many fan, low pressure, high pressure compressor stages.
- Air mass flow per second
- combustor design
- Turbine inlet temperature
- # of high & low pressure turbine stages
- Stator vanes control as per speed
- Afterburner design
- Bypass ratio
- fixed/variable cycle engine

2) Airframes are designed around an engine, not the other way around so there should be some metric to compare the engines. Planes with similar trust-to-weight ratios but with different bypass ratio engines will have radically different aerodynamic performance.

yes that's obvious - the engines inside an airframe weight category will certainly create differences in airframe peformance. And competing parties may win/loose based on engine. But like said above, engine metric are many.
In last 1 year gradually i have made a huge excel sheet of all current jet fighters mentioning their engine & airframe specs, basically the Wikipedia data, but i have arranged them in increasing airframe gross weight. The zoomed-out screenshot is just for prudence that i have done some preliminary homework.
If i sort the sheet based on T/W ratio &/or bypass ratio then the list will become random & staggered w.r.t. airframe size/weight bcoz the # of engines also differ.
Perhaps i need to make a separate engine comparison list.

3) Airframe performance depends on far more factors than just T/W ratio for example Tu - 160 with a t/w ratio .37 is a supersonic bomber and can remain at supersonic speed for longer durations compared to planes with far better T/W ratio

I already said similar thing in a different way

practically, how fast will a jet go depends on
- airframe weight at the time
- engine design
- altitude (air density), friction force.
- airframe design producing certain amount of lift & drag due to friction & shockwaves.
- special feautures like shock compression lift.

2 same jets with different wing & fuselage design but with same # & type of engine(s) will have different performance.

 

[fire starter]

Titanium alloys for amca.