- Joined
- Jul 5, 2024
- Messages
- 459
- Likes
- 2,062
DRDO and PSU's
- Thread starter 125mm_Smoothbore
- Start date
- Joined
- Jul 5, 2024
- Messages
- 281
- Likes
- 973
was looking for this place
In context of ground test run of HAL Warrior and it "lack" of stealth shaping and serrations, it could be that they will be added for the in-production vehicles and they wanted to fly & test out the "simpler" version first. But, it's possible that what I had been saying about the "fall" in importance of shapes and "rise" in importance of the materials (RAM, RAS, paints/coats) in stealth vehicles going forward is starting to happen.
Why would a designer pay the aero-dynamic penalties of "stealth-shaping" when some materials can give a -20dB (99%) reduction over a broadband C,X and Ku band and -10dB (90%) over the whole range of 38GHz band of frequencies?
So, low drag more manuverable designs with newer materials will be just as stealthy as older less kinematic performance designs with shaping.
I usually post about RAMs. But I have been reading up on Thermal Barrier Coatings (TBCs) lately.
I always wondered is there a limit to how much rising the Turbine Entry Temp (TeT) can increase performance and if there was an upper limit to it. In the CAPS talk, GTRE director talked about
"gas adiabatic temp of hydrocarbons in air". I looked into it, turns out 2220 deg K (1950 deg C) is the gas adiabatic temp of hydrocarbons in air. So, there is no point in hitting temp above this ~2000 deg C is the highest temp a gas turbine aero-engine needs to achieve.
In that context, I saw a research going on in IIT Patna where they realized a TBC which survives something near 2000 thermal cycles at 1800 deg C (2073 deg K) with no major problems (like spallation). There was also an interesting work on a bond-coat less TBC (lighter) with CNTs which also shows 48 cycles at 1800 degC.
Why would a designer pay the aero-dynamic penalties of "stealth-shaping" when some materials can give a -20dB (99%) reduction over a broadband C,X and Ku band and -10dB (90%) over the whole range of 38GHz band of frequencies?
So, low drag more manuverable designs with newer materials will be just as stealthy as older less kinematic performance designs with shaping.
I usually post about RAMs. But I have been reading up on Thermal Barrier Coatings (TBCs) lately.
I always wondered is there a limit to how much rising the Turbine Entry Temp (TeT) can increase performance and if there was an upper limit to it. In the CAPS talk, GTRE director talked about
"gas adiabatic temp of hydrocarbons in air". I looked into it, turns out 2220 deg K (1950 deg C) is the gas adiabatic temp of hydrocarbons in air. So, there is no point in hitting temp above this ~2000 deg C is the highest temp a gas turbine aero-engine needs to achieve.
In that context, I saw a research going on in IIT Patna where they realized a TBC which survives something near 2000 thermal cycles at 1800 deg C (2073 deg K) with no major problems (like spallation). There was also an interesting work on a bond-coat less TBC (lighter) with CNTs which also shows 48 cycles at 1800 degC.
Armenia to tow Indo-French artillery gun system
India and France have developed the Trajan 155 mm towed artillery gun system. Armenia has chosen this system for its forces. Several subsystems of the gun were developed in India. Deliveries will happen in the coming months. Armenia is also getting Pinaka multi-barrel rocket launchers and Akash...
"The artillery system has been tested by the Indian Army and has met all qualitative requirements, including operations in varied terrains - from marshy plains to high-altitude cold deserts. However, it was not ordered by the Army after an earlier procurement plan was abandoned."
Why no ATAGS?Armenia to tow Indo-French artillery gun system
India and France have developed the Trajan 155 mm towed artillery gun system. Armenia has chosen this system for its forces. Several subsystems of the gun were developed in India. Deliveries will happen in the coming months. Armenia is also getting Pinaka multi-barrel rocket launchers and Akash...economictimes.indiatimes.com
View attachment 21998
"The artillery system has been tested by the Indian Army and has met all qualitative requirements, including operations in varied terrains - from marshy plains to high-altitude cold deserts. However, it was not ordered by the Army after an earlier procurement plan was abandoned."
- Joined
- Jun 30, 2024
- Messages
- 778
- Likes
- 8,416
Wish they could give a figure for the size of this order.
- Joined
- Jul 6, 2024
- Messages
- 308
- Likes
- 2,266
- Joined
- Sep 29, 2024
- Messages
- 2,235
- Likes
- 11,759
France is Armenia's only Great Power patron.
As in they take open panga with Aliyev, Putin and Erdogan for Armenia's sake, We only supply them weapons.
Such a joint venture means both their friendly countries are happy
- Joined
- Sep 29, 2024
- Messages
- 2,235
- Likes
- 11,759
View: https://x.com/AdithyaKM_/status/1879721518361710951
Army chief throws weight behind ALH, says it will remain workhorse
Aayein?
- Joined
- Jul 1, 2024
- Messages
- 1,189
- Likes
- 6,465
BDL will give contract to KSSL for seeker assembly in a few weeks, number should be available there.
last time it was 1000 kits.
- Joined
- Jul 2, 2024
- Messages
- 470
- Likes
- 1,312
Let's try to understand few points. Sorry if i'm wrong, do correct me as required :
> There are some rules of nature which simply can't be bypassed, at least not with present tech.
for example perpendicular wing of F-18 gives high lift but also high drag but bad for RCS.> The aerodynamic penalty" of 1st-4th gen jets is higher than stealthy 5gen jets bcoz the the former hangs the weapons outside exposed to air resistance, while later hides the weapons behind serpentine intake(s).
You can check this post on AMCA where i've used 19 screenshots, some into a collage, to understand basics of aerodynamic, drag, shaping.
At this time with basic knowledge i would guess AMCA's Supercruise with F414
> 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...
Perhaps Yes, between Mach 1.2 to 1.4Agenda - supercruise
Can AMCA SUPERCRUISE with F414?
YesSHOULD AMCA supercruise withF414?
> 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...
> So we see that we dont live in a loss-less world. Ground vehicles have high friction, sea vessels & subs have big resistance by dense water & pressure. Similarly air provides its own challenges of friction & sonic barriers what we call "aerodynamic penalty". But for a particular speed the air friction/resistance/drag < liquid friction/resistance/drag < solid friction/resistance/drag.
On ground we write equations like (F - uMG = Ma). "u" the co-efficient of friction can be different as per terrain & some people panic by seeing/hearing about friction force, but ultimately the gross engine power has to propel the vehicle as desired, be it bike or MBT.
Similar equations are there as per fluid dynamics for both sea & aerial vehicles. There is Cd or coefficient of Drag. Some people panic by seeing its graph & values but ultimately the gross jet power has to propel the jet as desired & designed.
> Certain wing shapes try to minimize RCS but also give lift like diamond, cropped diamond, compound delta, cranked arrow or lambda, etc.
> Hence the tech evolution of more powerful engines & clever shaping have already overcome the "aerodynamic penalty" yet having low RCS.
> Now which "older less kinematic design with shaping" stealth jet you are comparing with?
> After so many experimental & prototype design around the world also, there is no perfect formula for creating perfect combat jet. Somethings have to be prioritised more over other aspects. Saving pilot's life & costy assets means prioritising stealth.
> 99% RCS reduction may not be enough. 99% of what intial value? The RCS of 4gen jets:
Initial models of F-16, a light jet - 4 sqm
Later models with composite body - 1 sqm down to 0.1 sqm
20 Dbsm ~ 100 sqm (B-52)
10 Dbsm ~ 10 sqm (big 4gen fighter)
0 Dbsm ~ 1 sqm (small 4gen fighter)>>>>100%
-10 Dbsm ~ 0.1 sqm (composite body 4gen fighter w/o shaping TODAY) >>>>>10% (90% reduction)
-20 Dbsm ~ 0.01 sqm (composite body 4gen fighter with RAM w/o shaping TODAY)>>>>> 1% (99% reduction)
-30 Dbsm ~ 0.001 sqm (F-35, composite 5gen body with shaping+RAM in 1990s)>>>>100%
-40 Dbsm ~ 0.0001 sqm (F-22, composite body 5gen with shaping+RAM in 1990s)>>>>10% (90% reduction)
N/6G prototype tested TODAY after 30 years since 1990s ~ ??
N/6G IOC jet after 5-10 years from TODAY, 40 years since 1990s ~ ??
So, our claim/achievement 0.01 sqm with RAM w/o shaping TODAY = 100x 0.0001 sqm with RAM & shaping in 1990s
If we use shaping+RAM then we might get further 10x or 90% reduction = 0.001 sqm like F-35.
But if NGAD R&D manages to get further 10x reduction to 0.00001 sqm or -50 Dbsm then our shaping+RAM RCS 0.001 sqm = again 100x 0.00001 sqm of NGAD
I looked at public data of all fighter jet engines & found highest TIT (Turbine Inlet Temp.) of F-35's F135 engine to be 2260 K or 1980 C. But there are other contributing factors as well - OPR, BPR, fuel type, fuel-air mix ratio, combustor design, turbine design, mixer design, etc
- Joined
- Jul 1, 2024
- Messages
- 31
- Likes
- 156
Armenia to tow Indo-French artillery gun system
India and France have developed the Trajan 155 mm towed artillery gun system. Armenia has chosen this system for its forces. Several subsystems of the gun were developed in India. Deliveries will happen in the coming months. Armenia is also getting Pinaka multi-barrel rocket launchers and Akash...
View attachment 21998
"The artillery system has been tested by the Indian Army and has met all qualitative requirements, including operations in varied terrains - from marshy plains to high-altitude cold deserts. However, it was not ordered by the Army after an earlier procurement plan was abandoned."
assemble in france .....build the components in india and sell it to ukraine
- Joined
- Jul 6, 2024
- Messages
- 308
- Likes
- 2,266
This does not include 26K crores sanctioned for 52 spy sats,if we add that then the total budget is 61.7K crores,some of the budget here is for infrastructure as well, so govt is willing to spend money, if the govt is willing to spend this much money in space sector, why aren't they releasing money for jet engines & Test Facilities?? Who is at fault here ??
View: https://x.com/TitaniumSV5/status/1879872737965142344
View: https://x.com/TitaniumSV5/status/1879872737965142344
>Well, what I understood, you are comparing a generic stealth aircraft vs 4th gen.Let's try to understand few points. Sorry if i'm wrong, do correct me as required :
> There are some rules of nature which simply can't be bypassed, at least not with present tech.
> The aerodynamic penalty" of 1st-4th gen jets is higher than stealthy 5gen jets bcoz the the former hangs the weapons outside exposed to air resistance, while later hides the weapons behind serpentine intake(s).
You can check this post on AMCA where i've used 19 screenshots, some into a collage, to understand basics of aerodynamic, drag, shaping.
At this time with basic knowledge i would guess AMCA's Supercruise with F414
Perhaps Yes, between Mach 1.2 to 1.4Agenda - supercruise
Can AMCA SUPERCRUISE with F414?
YesSHOULD AMCA supercruise withF414?
> 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...
> So we see that we dont live in a loss-less world. Ground vehicles have high friction, sea vessels & subs have big resistance by dense water & pressure. Similarly air provides its own challenges of friction & sonic barriers what we call "aerodynamic penalty". But for a particular speed the air friction/resistance/drag < liquid friction/resistance/drag < solid friction/resistance/drag.
On ground we write equations like (F - uMG = Ma). "u" the co-efficient of friction can be different as per terrain & some people panic by seeing/hearing about friction force, but ultimately the gross engine power has to propel the vehicle as desired, be it bike or MBT.
Similar equations are there as per fluid dynamics for both sea & aerial vehicles. There is Cd or coefficient of Drag. Some people panic by seeing its graph & values but ultimately the gross jet power has to propel the jet as desired & designed.
> Certain wing shapes try to minimize RCS but also give lift like diamond, cropped diamond, compound delta, cranked arrow or lambda, etc.
> Hence the tech evolution of more powerful engines & clever shaping have already overcome the "aerodynamic penalty" yet having low RCS.
> Now which "older less kinematic design with shaping" stealth jet you are comparing with?
> After so many experimental & prototype design around the world also, there is no perfect formula for creating perfect combat jet. Somethings have to be prioritised more over other aspects. Saving pilot's life & costy assets means prioritising stealth.
> 99% RCS reduction may not be enough. 99% of what intial value? The RCS of 4gen jets:
Initial models of F-16, a light jet - 4 sqm
Later models with composite body - 1 sqm down to 0.1 sqm
20 Dbsm ~ 100 sqm (B-52)
10 Dbsm ~ 10 sqm (big 4gen fighter)
0 Dbsm ~ 1 sqm (small 4gen fighter)>>>>100%
-10 Dbsm ~ 0.1 sqm (composite body 4gen fighter w/o shaping TODAY) >>>>>10% (90% reduction)
-20 Dbsm ~ 0.01 sqm (composite body 4gen fighter with RAM w/o shaping TODAY)>>>>> 1% (99% reduction)
-30 Dbsm ~ 0.001 sqm (F-35, composite 5gen body with shaping+RAM in 1990s)>>>>100%
-40 Dbsm ~ 0.0001 sqm (F-22, composite body 5gen with shaping+RAM in 1990s)>>>>10% (90% reduction)
N/6G prototype tested TODAY after 30 years since 1990s ~ ??
N/6G IOC jet after 5-10 years from TODAY, 40 years since 1990s ~ ??
So, our claim/achievement 0.01 sqm with RAM w/o shaping TODAY = 100x 0.0001 sqm with RAM & shaping in 1990s
If we use shaping+RAM then we might get further 10x or 90% reduction = 0.001 sqm like F-35.
But if NGAD R&D manages to get further 10x reduction to 0.00001 sqm or -50 Dbsm then our shaping+RAM RCS 0.001 sqm = again 100x 0.00001 sqm of NGAD
I looked at public data of all fighter jet engines & found highest TIT (Turbine Inlet Temp.) of F-35's F135 engine to be 2260 K or 1980 C. But there are other contributing factors as well - OPR, BPR, fuel type, fuel-air mix ratio, combustor design, turbine design, mixer design, etc
My comment was in context of HAL Warrior. It's obvious a 4th gen with weapons hanging outside will get more draggy than a 5th gen which is "clean". But, say a 4th gen carries it weapons,payload, other protrusions (ex : Air Data Systems, etc) inside but dosen't use the aligned sharp edges, faceted surfaces, etc, as much then said 4th gen (probably, not 4th gen anymore) will face lower drag than a 5th gen which uses those. I am no aerodynamics expert, but what I understand, 5th gen with smaller diamond wings also have lift and pressure recovery problems as well.
As you said, they tried to mitigate it with more powerful & efficient engines, but using these engines in these new designs that leverage "materials" more than "shape" will get even better performance.
>Now, as you said everything is a trade, I just think, the trend in stealth fighters going forward will be the following:
Don't use stealth shapes as much in the jet, Instead leverage materials to get the stealth
So, you get a stealthier jet which is more aerodynamically better (a super manuverable stealth jet)
Then, we need to rely on TVCs less (which have their own issues, even the future fluidic TVCs)
>Now, coming to the RCS reduction thing. -XdB (X is any value) is the standard reporting convention. It's not 99% reduction of a given RCS value. It's 99% absoprtion of incoming radiation. So, think of it as a flat plate which absorbs 99% radar waves. When applied on jets, it would be much better as an aircraft is not a flat plate. Plus, all these are thin single layer RAM, they improve dramatically with multilayering.
>I would also urge you to not take those RCS values of globalsecurity.org very seriously, 99% absorption is very difficult for radars to detect today (& for quite sometime in the future) at useful ranges. They would still be some shaping needed but quite less than what used to be the case. So, applying these materials in the aircraft will get you much better RCS reduction -> through just the normal shape of a aircraft & multilayering probably close to the values you are quoting. And, will get even better with "some" stealth shaping.
>Besides F22 or even F35 don't have broadband absorbers like these, they are usually optimized for
X-band and a few other bands with different abosrbers for different bands. The metamaterial tech was invented in 2008-2009 and took off recently. (Usually, F35 fanboys post about a Lockheed patent about CNTs absorbers, but it dosen't say what they think it does. I sort of prempted any F35 fanboys)
>As for the F135 engine, I still think that's a fanboy estimate of TeT, but it's well known that aero-engines are reaching the "gas adiabatic temp of hydrocarbons in air". GTRE director mentioned in CAPS event as well. That means, there is no point in increasing TeT much beyond this. Ofcourse, pumping more oxygen will raise the gas adiabatic temp of hydrocarbons in air, but how much more oxygen can be cramped into the combustor in a vehicle flying through air? At the adiabatic temp, the entire generated heat is converted into work theoretically.
> Maybe that's why folks are trying to change the fuel (H2,etc are active research areas), electro-gas turbines which run the compressor and turbine at different speeds, lighter materials for engines, etc, will continue giving dividends for gas turbine going forward.
Latest Replies
-
Indo US Relations- shade2
-
Indian Politics and Democracy
- Miss Firing
-
Indian Navy Developments & Discussions
- Ayan Barat
-
DRDO and PSU's
- Ajax
-
Cricket- SKC
-
Jokes Thread- Baseplate
-
Indian Army: News and Updates
- Soldier35
-
Sinking State of Bangladesh: Idiotic Musings
- Miss Firing
