India AMCA Program

[Nilgiri]

Addendum to what I posted above:

Wing area vs MTOW for F-22 vs F-35 and HAL AMCA (provisional) for basic L/D comparison

i.e AMCA closer to ratio of F-22 here.

F-22 MTOW = 38 ton, wing area = 78, wingspan = 13.56, AR = 2.36
F-35 MTOW = 30 ton, wing area = 43, wingspan = 11, AR = 2.81
AMCA* MTOW = 25 ton, wing area = 55, wingspan = 11.13, AR = 2.25

Wave drag reduced by lower AR (supercruise at M 1.5+, given massive wave drag spike at mach 1 region), hence why F-22 AR compared to F-35

i.e F-22 more optimised to supersonic combat, F-35 subsonic and transonic.

http://www.stengel.mycpanel.princeton.edu/MAE331Lecture5.pdf

page 14

https://apps.dtic.mil/sti/tr/pdf/ADA377310.pdf

page 19

 

[Gessler]

Looks like work on the DAS prototype has begun...

The proof of concept for the sensor fusion software looks like it'll only have 2 sensors to begin with. The system would probably be integrated on the DRDO A319 FTB first...

...not unlike how F-35's EODAS was first fitted on the B737 FTB:

 

[Radonsider]

With 2 sensors wouldn't it be hard? Maybe just for testing

 

[Gessler]

With 2 sensors wouldn't it be hard? Maybe just for testing

Yes - just to get the sensor fusion working. Eventually it should have 6 apertures.

 

[Nilgiri]

https://twitter.com/i/web/status/1776483159460515896

 

[Afif]

https://twitter.com/i/web/status/1776483159460515896

As you know my knowledge in this domain is primitive. But how does DRDO finish CDR before even having an actual workable prototype? Don't you first need a tech demonstrator like YF-22, X-35 and KAAN today?

 

[Nilgiri]

As you know my knowledge in this domain is primitive. But how does DRDO finish CDR before even having an actual workable prototype? Don't you first need a tech demonstrator like YF-22, X-35 and KAAN today?

This is essentially the CDR for a prototype and tech demonstrator.

Just like those 3 you mention all would have had CDR done before fabricating the prototype.

X-35 for example had its CDR ~ 1998, fabrication over two years and first test flight in 2000.

The F-35 TD could then use this earlier CDR to get going in parallel while the CDR for the F-35 series production was constructed with the design feedback from all of this (I think in 2006 or some such year, I forget the year).

But there always has to be a CDR completed at some stage for there to be fabrication and assembly.

 

[Windchime]

As you know my knowledge in this domain is primitive. But how does DRDO finish CDR before even having an actual workable prototype? Don't you first need a tech demonstrator like YF-22, X-35 and KAAN today?

You are misunderstanding what a CDR actually is. Look up what the term "design review" means in system engineering. In terms of military acquisition, a lot of the countries base their processes on the US DoD practice, so I suggest you reading following link

https://aaf.dau.edu/aaf/mca/cdr/

Also, you are getting it the other way around. Manufacturing of any prototype follows a design review, not vice versa. That design review is typically critical design review, since you need to have finished most critical designs to build a representative prototype. A TD vehicle is not a premise for fighter development.

 

[Nilgiri]

Australia mil aviation history featured a summary look into the HAL AMCA.

 

[Gessler]

Good news for AMCA:

https://twitter.com/i/web/status/1791506329565339880

https://twitter.com/i/web/status/1791508456312324255

@Nilgiri

Information regarding the plan for the 50k-ton press was revealed in HAL's investors call.

 

[Spitfire9]

While there is no great urgency for AMCA Mk1 to get a licence production GE F414 deal arranged quickly, it is nearly a year since the MOU for such was announced and there is more urgency to get an engine deal finalised for Tejas Mk2 (and as a consequence, that will be the deal for AMCA Mk1, too). As time goes by India will simply have to accept whatever ToT GE is prepared to offer, won't it, to avoid delay in Tejas Mk2 being delivered to IAF?

Can a deal be done until the alleged Involvement of India in the Khalistan-related assassination is clarified? I wonder how long that will take.

What about the engine for AMCA Mk2 - is there any concrete progress on that?

 

[Zapper]

As time goes by India will simply have to accept whatever ToT GE is prepared to offer, won't it, to avoid delay in Tejas Mk2 being delivered to IAF?

I'm sure no country would be willing to offer ToT on the engine's hot core. Even during the Rafale offset deal, Snecma wanted to use their hot core instead. China spend billions in R&D, IP espionage, hiring Russian engineers for their WS series engine and it's unknown if the engine is capable to generate the required dry & wet thrust

 

[Spitfire9]

It is reported in Indian media that AMCA design is advancing

HAL Achieves Major Milestone in AMCA Stealth Fighter Development – Indian Defence Research Wing

idrw.org

If the design is not yet settled, is a completed prototype still possible (as HAL earlier said) within 3 years of CCS approval in March 2024?

Incidentally, I read elsewhere (Indian paper online) that there is a new proposal that production be undertaken through a company jointly owned by ADA and HAL. Has the SPV proposed been abandoned due to lack of interest from the private sector?

 

[JOYDEEPGHOSH]

6th Gen #NGAD Vs 5th Gen #F35 Comparison

6th Gen NGAD Vs 5th Gen F-35 Comparison

F-35 Vs. NGAD Concept Indian Air Force/IAF is happy flying 3rd Gen, 4th Gen, and 4.5++ Gen fighters like Mig-29/29K, Rafale/Ra...

rbt-defense.blogspot.com

 

[Bhartiya Sainik]

I was looking at some numbers a bit earlier:

F-22, 2xF-119 = 232kN

Using gross weight (roughly halfway between empty and MTOW) of 29.4 tons and dry thrust only
gives T/W of 232/(29.4x9.81) = 0.8

Equiv numbers for supercruise capable a/c:
Rafale ~ 0.68
EF ~ 0.76
Su-57 ~0.72
Gripen E/F ~ 0.82

When this is done for F-35A (not capable of sustained supercruise with most combat loads), the T/W number is ~0.60

Using Gripen x2 essentially (i.e T/W of 0.82 and keeping engine 414 the same too), we get weight supported as ~ 24 tons

So if combat loads for AMCA are well within this and parasitic drag (of 5th gen harsher aerodynamics compared to 4th gen) is mitigated sufficiently, then it should be able to supercruise in a number of commensurate configurations barring some potentially above this weight (and drag of external payloads in MTOW configurations).

We will have to see but nothing stopping a 2xF414 platform (w.r.t only their dry thrust) from supercruise if you keep the payload (T/W) and L/D characteristics within desired ranges for it.

Or has a more robust analysis of this been done somewhere?

You share very informative stuff.
I think we should use only IWB jets to compare with AMCA bcoz the IWB itself will add some weight. depending upon design.

On a light note, i think F-35 is an intentional blunder bcoz it is a JSF for export, unlike F-22 with export ban. F-35A although uses lifting body, has less wing area means lesslift, low sweep angle of leading edge means higher drag. F-135 engine currently most powerful but just 1 engine to reduce maintenance, reduces airframe T/W ratio also.

AMCA will use F414 bcoz of Indo-US business diplomacy perhaps. If we didn't have that also then we would have cracked a deal with French to use M-88 or with Russians to use RD-93.

I guess you already know about this graph on sonic drag

So ideally an aircraft should supercruise beyond Mach 1.8 at least. The danger zone is 0.9 to 1.5

Also, there is the "Whitcomb Area Rule" to shape a fuselage of jet to reduce the drag. Supersonic Area rue also there as per which the aircraft body need to be within the Sonic-Cone.

Different sources give different data on Supercruise
For example F-22,

F-22 Empty weight 19.7 T + 50% fuel 4.1 T + full IWB 8 AAMs 1.1 T = 24.9 tons
Airframe T/W ratio at 100% power = 2x(116 to 120.3)/9.8 /24.9 = 0.94 to 0.98

F-35A Empty weight 13.3 T + 50% fuel 4.15 T + 4 AAMs 0.6 T = 18.05 tons
Airframe T/W ratio at 100% power = 128.1/9.8 /18.05 = 0.72
But F-35 cannot supercruise due to multiple factors like lower wing sweep angle creating higher drag, etc.

AMCA empty weight 12 T + 50% fuel 3.25 T + 4 Astr MK3 SFDR 0.88 T = 16.13 tons
T/W ratio at 100% power = 2x58/9.8 /16.13 = 0.73
AMCA wing has higher sweep angle creating lesser drag.
So perhaps AMCA also would be able to supercruise at say M 1.2

When new engine with 75 KN dry thrust will be available then hopefully 6 AAMs will be carried.
T/W ratio at 100% power = 2x75/9.8 / (16.13 + 0.44) = 0.92
Then hopefully AMCA will supercruise around M 1.5+

 

[Bhartiya Sainik]

AGENDA - AMCA's SUPERCRUISE

Different people speculate AMCA to Supercruise b/w Mach 1.2-1.4 with F414 engines & Mach 1.5-1.6 with JV engine producing 75 KN dry thust.
> On one side we have Mother Nature's unbeatable laws of PCM putting limits of performance - higher drag, higher KE required, higher complexity design.
> On the other side we have global engineers pushing for Speed (both cruising & maximum) -
Turboprop -> Turbojet/fan -> Ramjet -> Turbo-Ramjet -> Variable cycle adaptive engine
> KE required increases as square of velocity, looks like panic, but comes from Calorific value of researched fuels with secret sauce & ingredients - small volume but big kick, especially after compression.
> Currently SuCr is attached to Turbo-jet/fan, considered an "overkill", inefficient, gimmick, etc by many as per Performance studies on engine types. Some would say it is war-time mode/feature which it is.
But if nations're already prepared to do it in war-time since 3 decades & will continue in future also then what can civillians do?

Supercruise provides ability to -
- launch weapons to have higher range w/o increasing IRS of jet.
- Intercept targets better.
- Evade enemy's weapon.

In peace time, fighter jets fly subsonic due to multiple reasons -
- Sonic booms disturbs residential areas.
- Fuel efficiency. Typically, less/more throttle means less/more fuel flow means less/more thrust/speed/distance flown.

Jet engines like Turbo-jet/fan have their efficiency boundaries but still since decades scientists & engineers are working on better airframe design & engine to use same amount of fuel but achieve higher thrust/speed/distance travelled.

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

If we take 3 Supercruising jets - F-22 (SuCr M 1.8), Rafale (SuCr M 1.4), EF-2000 (SuCr M 1.5) & their engines F119, M-88-2, EJ-200 & compare with F414 then it is very difficult to find governing reason resulting in max dry thrust bcoz there are many permutations & combinations of individual engine parts design & performance.
I created a graph, manipulating the values up/down to bring the graph lines closer to visually compare better:

We see that -
> Turbine inlet temp. is a very low slope line. It takes a dip with EJ-200.
> Inlet diameter, inlet area, engine weight, volume, air mass flow show identical increasing trend.
> But, Engine length, dry thrust, dry T/W ratio, dry T/Vol ratio, Bypass ratio take a dip with F414.
So the big dip in Bypass ratio might have impacted dry thrust & then dry T/W ratio, dry T/Vol. ratio. I wonder if engine length also influenced it.
> # of compressor & turbine stages take a dip with EJ-200. This could have affected compression ratio also.
> F119's # length, inlet dia/area, body volume, weight, air mass flow jumps obviously.
But # of stages, compression ratio, fuel SFC, take a BIG dip but impacting its dry T/W & T/Vol ratios
STILL its dry thrust is like DOUBLE.

Fuel consumption is measured in units like g/KN/s or lb/lbf/hr, called SFC or Specific Fuel Consumption. But different people can use different metrics like fuel used as per airframe weight, distance travelled, etc.

F-22's F119 engine's SFC with inlet dia. 100cm at 100% power (116-120.3 KN) is around 17 g/KN/s.
2 engines, so F-22 SFC is 34 g/KN/s at 100% power & Sup.Cr. Mach 1.5-1.8 (514.5-617.4 m/s).
So 3.94-4Kg/s fuel for covering 514.5-617.4 m/s or 128.6-156.7 m/Kg or 6.38-7.77 gm/m.
Empty weight 19.7 T + 50% fuel 4.1 T + full IWB 8 AAMs 1.1 T = 24.9 tons
Airframe T/W ratio at 100% power = 2x(116 to 120.3)/9.8 /24.9 = 0.94 to 0.98
Fuel per ton = (3,940-4,000)/24.9 = 158.23-160.64 gm/s/T.
50% fuel 4.1 tons while supercruise will be depleted in 1,025-1040 seconds or 17-18 minutes covering 527-642 Kms.


GE F-414 engine's SFC with inlet dia. 79cm at 100% power (57.8-61.83 KN) is 20.5-23.25 g/KN/s depending upon model. 75 KN JV engine is planned.
2 engines, so AMCA SFC will be 41-46.5 g/KN/s at 100% power.
So 2.37-2.87Kg/s fuel will be used.
AMCA empty weight 12 T + 50% fuel 3.25 T + 4 Astr MK3 SFDR 0.88 T = 16.13 tons
T/W ratio at 100% power = 2x58/9.8 /16.13 = 0.73
Fuel per ton = (2,370-2,870)/16.13 = 146.93-177.92 gm/s/T.
let's assume that with 0.73 T/W AMCA can also supercruise at M 1.2 (411.6 m/s).
50% fuel 3.25 tons while on supercuise will be depleted in 1,132-1,371 seconds or 18-23 minutes covering 466-564 Kms.
When new engine with 75 KN dry thrust will be available then hopefully 6 AAMs will be carried.
T/W ratio at 100% power = 2x75/9.8 / (16.13 + 0.44) = 0.92
Then hopefully AMCA will supercruise around M 1.5


Rafale's M-88-2 engine's SFC with inlet dia. 70cm at 100% power (50KN) is 22.14 g/KN/s.
2 engines, so Rafale SFC is 44.28 g/KN/s at 100% power & Sup.Cr. Mach 1.4 (480.2 m/s).
So 2.21 Kg/s fuel for covering 480.2 m/s or 217.28 m/Kg or 4.6 gm/m.
To go this extra 59 m/Kg-fuel Vs F-35, the SFC is increased from 20.3 to 22.14 g/KN/s.

EF-2000's EJ-200 engine's SFC with inlet dia. 74cm at 100% power (60 KN) is 21-23 g/KN/s.
2 engines so EF-2000 SFC is 42-46 g/N/s at 100% power & Sup.Cr. Mach 1.5 (514.5 m/s).
so 2.52-2.76 Kg/s fuel for covering 514.5 m/s or 186.41-204.16 m/Kg or 4.9-5.36 gm/m.

So we see that Rafale with empty design weight 8.5 T, 492 sqft clipped delta wing & 50KN engine can supercruise at M 1.4
but F-18E/F with empty design weight 14.5 T, 500 sqft. trapezoidal wing & 58 KN engine cannot due to 6T weight increase due to carrier-ops MLG & other things & higher drag wing.

 

[Bhartiya Sainik]

I mentioned about DRAG where people panic a lot. We should dive little more into it.

Drag are of many types

Some drag increase with speed & some decrease, but total drag increase.

That's why most people panic even before calculating. Why the world is pushing for increasing cruise & max speed?

The propulsion performace of Turbo-fan is limited around Mach 1.6 aspergraph below. Yet we see F-22 SuCr at M 1.8 with F119 engnes whose SFC is lowest 17 gm/N/s at 100% throttle. So there is definitely something(s) classified.

(File:Specific-impulse-kk-20090105.png - Wikimedia Commons)
(File:Gas turbine efficiency.png - Wikimedia Commons)

That means if military is persistent on SuCr then we civillians are stuck with something somewhere, perhaps with engine efficiency & drag graphs are bothering us too much, while there are structural factors also.

We should keep in mind that objective, priorities of military & civil jets are different.
MoD & Air force also have budget & SOP for peace time Ops incl. pre-planned routes, responses,flight altitude, speed kkeping in mind min. fuel expenses, maintenance & spares charges, etc.
But design focuses on war time performance also.

Let's look at the collage of drag, the highlighted part of graph in green color.
Real world is not ideal but full of resistance, losses, still as wing sweep angle increases, the drag decreases drastically.
Coefficient of drag Cd & Fd Force of drag are different, just like (Cf=u) coefficient of ground friction & (F=u.M.g) ground friction force.

So just like ground force equation (F - Mg = Ma), we need Flight equation of motion. As per the scope of forums, we common people enthusiasts don't need complex 3-axis equation including roll, pitch, yaw, like Navier-Stokes equation, etc. But this kind of forum has to go on for 1-2 decades at least.
Let's take a basic example of level flight. Make corrections/alterations where you like.

But for our low IQ minds, we need a simplified formula for overall drag - The Drag equation

Fd increases as square of Velocity, but
the Cd of swept wing jet is 0.02 +/-
Air density at cruise altitudes is < 1 Kg/M^3. At 30Kft it is 0.458, at 50kft it is 0.186

NOTE - Make corrections/alterations as required.
Drag Force Equation Fd = (1/2) (Air density X Cd X Cross Section Area X Velocity^2)
Air density @ 40,000 feet = 0.3 Kg/m^3
Coefficient of drag Cd for wing sweel angle around 50 degrees = 0.02
Speed let's consider Mach 1.2 (411.6 m/s, round down to 410 m/s) which is considered bad for SuCr
Cross Section Area of AMCA at wingtip level, let's say = 8 m^2

Fd = (0.3 X 0.02 X 8 X 410 X 410)/2 = 4,034.4 N = 4.034 KN
If 2 F414 engines together produce 2x58 KN = 116 KN dry thrust
then net thrust = T - Fd = 112 KN, it is like an engine with 56 KN dry thrust
It is analogous to 116 people are pulling something forward & 4 people are trying pull behind.
Net result is 112 pulling forward. This is simple theoretical level-flight example. I am curious to know actual values.

GE F-414 engine's SFC with inlet dia. 79cm at 100% power (57.8-61.83 KN) is 20.5-23.25 g/KN/s depending upon model. 75 KN JV engine is planned.
2 engines, so AMCA SFC will be 41-46.5 g/KN/s at 100% power.
So 2.37-2.87Kg/s fuel will be used.
AMCA empty weight 12 T + 50% fuel 3.25 T + 4 Astr MK3 SFDR 0.88 T = 16.13 tons
T/W ratio at 100% power = 2x58/9.8 /16.13 = 0.73
Fuel per ton = (2,370-2,870)/16.13 = 146.93-177.92 gm/s/T.
let's assume that with 0.73 T/W AMCA can also supercruise at M 1.2 (411.6 m/s).
50% fuel 3.25 tons while on supercuise will be depleted in 1,132-1,371 seconds or 18-23 minutes covering 466-564 Kms.
When new engine with 75 KN dry thrust will be available then hopefully 6 AAMs will be carried.
T/W ratio at 100% power = 2x75/9.8 / (16.13 + 0.44) = 0.92
Then hopefully AMCA will supercruise around M 1.5

Those who want deeper dive can include laws like conservation of momentum/energy/mass; equations of Navier-Stokes, Bernouli, Laplace, Euler, etc; Reynold's number, Critical Mach number, Stagnation pressure, etc, etc.

Practically the avionics computer of modern jet fighter is equivalent of compacted average Super-computer calculating many 3D equations every millisecond.
Computing power is measured in units like MIPS - Millions Instructions/Second & FLOPS - Floating Point Operations/Second).

So we see that real world physics will always have resistance but overall effect matters & as per that solutions or work-arounds are developed. Supercruise is war time feature & it will be used for reasons mentioned. The variable cycle engine will extend its usage.

 

[Bhartiya Sainik]

AGENDA - RAM (Radar Absorbent Material) for AMCA.

This is old news now. Our DoD organisations with some IITs have developed RAM paints, sheets named "Adrishya", "NiRaLa", etc, composite materials & working on geometric shaping starting with AMCA.
The RCS results would obviously be top secret.

There were some sheets also, somewhere on social media.

 

[Bhartiya Sainik]

@Nilgiri @Afif
I noticed that this website is putting its own icon on attached pics, especially skilled creation of others like 3D art, etc. Some pics are free to share as long as people maintain the credits, copyright watermark/owner's mark. Putting another mark could be seen as covetous, unethical, unprofessional, etc, impacting reputation of website.
This might even discourage new members.
Like some other forums, this website is also hosted in San Francisco by Cloudfare. This will make it easy for members to move on.

 

[Nilgiri]

@Nilgiri @Afif
I noticed that this website is putting its own icon on attached pics, especially skilled creation of others like 3D art, etc. Some pics are free to share as long as people maintain the credits, copyright watermark/owner's mark. Putting another mark could be seen as covetous, unethical, unprofessional, etc, impacting reputation of website.
This might even discourage new members.
Like some other forums, this website is also hosted in San Francisco by Cloudfare. This will make it easy for members to move on.

The watermark removes itself once the pic is hosted in-line with the post itself. See for yourself:

https://defencehub.live/attachments/1723049057708-jpeg.69992/

etc.

It (watermark during attachment process) is artifact from earlier issue on forum.