AMCA News and Discussions

Singha · Post by **Singha** » 16 Feb 2013 07:40

I hear its being whispered the meteor aam will need costly changes to fit within the JSF ,because the americans design their weapons bays to fit american weapons only.

keeping such things in mind and if the shape and size of the internal bay is frozen (freeze it early), we should build ourself a working example on the ground and fit dummy rounds of each and every missile and PGM for trials. secondly bolt it below a HS748 or EMB and do weapons release trials well before the AMCA even flies.....if we are pinning hopes on compact new weapons coming for PAKFA we should obtain samples from Rus and test them as well.

gnair · Post by **gnair** » 16 Feb 2013 08:31

Two things wished for the MCA that may be futuristic in value are:

1) If the vertical stabilizer is the size that it is, then every opportunity should be taken to fill it up with fuel, to optimize on endurance.
If it could be done on the civilian side of things, (B-747, 777-300, A-340) there is no reason why it can't be feasibility studied on the military end. And
2) The Central weapons bay has to be a quick plug and removal system, for an array of weapons that have been pre-defined, planned and stacked for the mission profile. eg. a load out of 4-6 missiles is pre-stacked in a tray. The tray is on a ammo cart. The cart gets rolled out to the under-belly and the whole pre-stacked, wired up weapons tray is loaded up in minimal quick turn around time, rather than the traditional piece by piece mounting of individual ordnance. In effect the weapons bay becomes a plug and play interchangeable LRU with its own built-in self test feature.

gnair · Post by **gnair** » 16 Feb 2013 08:54

indranilroy wrote:My questions are of a different kind ... why are the edges rounded on the stabilizers?

By the way, I did not like the AMCA design initially, but it is starting to grow on me .

Speculating more than anything else at this time:
edges could be rounded because of better manufacturing efficiency, could be less static build-up thereby avoiding a bunch of static wicks, better IR signature and possibly less accumulation in high precipitation/icing conditions.

SaiK · Post by **SaiK** » 16 Feb 2013 09:32

If we integrating stores from various countries, it is important to keep it modular in the marketing sense. I already see potential market for LCA.. so if we need to make a killing it is important, that selling the stores integration modules, and packages basically programmable and plugin mode so that countries pay us for the services and cost incurred in our R&D. modularity also helps in AMCA. LCA++ versions to test AMCA techs is vital for both LCA and AMCA.

Singha · Post by **Singha** » 16 Feb 2013 09:33

The vertical fins of su30mkk are claimed to have fuel tanks....

vasu raya · Post by **vasu raya** » 16 Feb 2013 09:39

For the said SEAD/DEAD role of the AMCA in the critical initial days one would expect that they fit the Sudarshan Chakra (Brahmos-H recently unveiled) and some ARMs in the internal bay.

Indranil · Post by **Indranil** » 16 Feb 2013 09:59

gnair wrote:
indranilroy wrote:My questions are of a different kind ... why are the edges rounded on the stabilizers?

By the way, I did not like the AMCA design initially, but it is starting to grow on me .
Speculating more than anything else at this time:
edges could be rounded because of better manufacturing efficiency, could be less static build-up thereby avoiding a bunch of static wicks, better IR signature and possibly less accumulation in high precipitation/icing conditions.

Then why do the wings have sharp tips?

Indranil · Post by **Indranil** » 16 Feb 2013 10:15

gnair wrote:Two things wished for the MCA that may be futuristic in value are:
2) The Central weapons bay has to be a quick plug and removal system, for an array of weapons that have been pre-defined, planned and stacked for the mission profile. eg. a load out of 4-6 missiles is pre-stacked in a tray. The tray is on a ammo cart. The cart gets rolled out to the under-belly and the whole pre-stacked, wired up weapons tray is loaded up in minimal quick turn around time, rather than the traditional piece by piece mounting of individual ordnance. In effect the weapons bay becomes a plug and play interchangeable LRU with its own built-in self test feature.

First their is a fundamental engineering question. Is the time of rearming the plane the bottleneck of its turnaround time.
Second, is it possible to build a tray which is low weight, low volume and yet doesn't deform during high G turns and weapon ejections.

member_20292 · Post by **member_20292** » 16 Feb 2013 10:30

Joey

1 yes. Check gripen
2 yes. New concept . Costs time money. Question is that are you ready to build 1000s of these canvas with weapons to the tight tolerances required of f22 type fighters ?

GeorgeM · Post by **GeorgeM** » 16 Feb 2013 11:08

Looking at the pics - front view and the iso view, it almost seems like some kind of conformal fuel tanks are 'built in'
Also the nose kind of resembles LCA-IN type, stooped and sharper drop.

Indranil · Post by **Indranil** » 16 Feb 2013 12:10

mahadevbhu wrote:Joey

1 yes. Check gripen
2 yes. New concept . Costs time money. Question is that are you ready to build 1000s of these canvas with weapons to the tight tolerances required of f22 type fighters ?

Well Chandler,

1. Grippen checked: Under ideal circumstances like fuel truck standing by refueling time is 7 minutes. Rearming time is 10 minutes. So, if rearming times goes to 0, you will still be saving 3 minutes. By the way red eyed pilot would kiss your hand for the seven minute gap you graciously granted him between missions and hoping that the time on the MTBF clock (which on the Gripen) is 7.2 hours.

2. I don't think you understand the complexity. The tray is dead weight and dead volume. So it has to be minimized. Yet you are asking it to do the following contradictory things:
a. To carry 500 kg bombs, each of which either push against the ceiling at 1.5 Tons or pull the ceiling at 4.5 Tons. Also imagine the point where this tray attaches to the body. It is pushing or pulling between 4 Tons to 12 Tons (assuming to bombs and 2 Astras from -3Gs to 9 Gs). Oh! and by the way the ejection system (atleast on the F-22) creates a force upto 40 G.
b. Do not deform. Because, ejection of arms from internal bays is dependent air flow inside the internal bay. If the missile does not eject, it might be a catastrophic.

For you reference the AVEL system on F-22 is made of very high grade aluminium and yet each one of them weigh 50 kgs.

member_20292 · Post by **member_20292** » 16 Feb 2013 20:37

Elementary my dear Joey.

2. I don't think you understand the complexity. The tray is dead weight and dead volume. So it has to be minimized. Yet you are asking it to do the following contradictory things:

I can tell you that there are composites that will, on doing the requisite RnD, be developed to those specs. Google graphene and carbon nanotube composites. Carbon nanotubes, individually, are orders or magnitude more (insert material strength property here) as compared to steel.

a. To carry 500 kg bombs, each of which either push against the ceiling at 1.5 Tons or pull the ceiling at 4.5 Tons. Also imagine the point where this tray attaches to the body. It is pushing or pulling between 4 Tons to 12 Tons (assuming to bombs and 2 Astras from -3Gs to 9 Gs). Oh! and by the way the ejection system (atleast on the F-22) creates a force upto 40 G.
b. Do not deform. Because, ejection of arms from internal bays is dependent air flow inside the internal bay. If the missile does not eject, it might be a catastrophic.

^^^ Sure, and I am sure that the specs required for such a device would be pretty demanding.

At the same time, I can promise you that it will be done in some time....materials science is a growing field.

negi · Post by **negi** » 16 Feb 2013 21:12

shiv wrote:Its not about composite fins. See the image below. All supersonic and near supersonic aircraft have tailfin leading edges that are swept back like their mainwings - mostly far more so than the AMCA model. Why?

Not only that in case of jet trainers or fighters it is required that at least 50% of the wet surface of the V fin remain outside of the wake from H fins (for spin recovery) hence they are usually placed in front of the H fins. I don't see that in that model in particular. All twin tail jets have their V fins placed in front of their H fins by a significant margin. See the hornets, fulcrums, flankars and even raptor and PAKFA they all have twin V tail config and are in front of their H fins a big margin. The model in Kanson's pic has them like that. Btw one reason why AMCA's V tail fins are bigger than other twin tail 5th gen fighters is they are not all moving but have conventional rudders.

Indranil · Post by **Indranil** » 16 Feb 2013 22:58

mahadevbhu wrote: I can tell you that there are composites that will, on doing the requisite RnD, be developed to those specs. Google graphene and carbon nanotube composites. Carbon nanotubes, individually, are orders or magnitude more (insert material strength property here) as compared to steel.

Graphene and carbon nanotubes have been around for long time now. Yet nobody has used them for providing hardpoints. Probably the orders of magnitude are not enough

mahadevbhu wrote: At the same time, I can promise you that it will be done in some time....materials science is a growing field.

Nothing to say against such a broad and sweeping statement.

member_20292 · Post by **member_20292** » 16 Feb 2013 23:33

.....in which he gracefully exits the argument....

gnair · Post by **gnair** » 18 Feb 2013 04:33

Then why do the wings have sharp tips?[/quote]
@indranilroy:
All trailing edges are sharp aren't they. They usually end as a part of the airfoil. Whether it is the stabilizer or the wing, they end with a very blade like form. I haven't seen anything out there that has a thick, blunt sort of cut-off. The only one I've heard about recently with a thicker, blunt cut off, is a new design they've incorporated in the PC-12NG, with their vertical stabilizer trim tab. Apparently it helps with adverse-yaw, and better deflection during the take off regime. PC-12's are centrifugal single engine turbines with a large prop, and the design will have to deal with that fact of life, despite the slap-on vortex generators placed along various critical areas of the air flow.

gnair · Post by **gnair** » 18 Feb 2013 04:49

Singha wrote:The vertical fins of su30mkk are claimed to have fuel tanks....

Wow, that's news!
So it does confirm that the plumbing is indeed feasible, on one of ours going forward. Too bad though the MKI doesn't have it but the MKK does and it's not even listed as of now, on future upgrades. Auxiliary fuel can always be used for engine start-up and taxi and the residue fed to the main tanks, just in case there are COG or stability concerns in combat flight mode.
With the MCA vertical stabilizer fixed+rudder rather than all-moving, maybe it's in the works, who knows!

SaiK · Post by **SaiK** » 18 Feb 2013 06:59

mmm.. how did you all come to a confirmation and feasibility? where is the data?

Singha · Post by **Singha** » 18 Feb 2013 07:24

Read the wiki entry on su30mkk. Its mentioned 280kg of fuel tanks between the two rudders.

SaiK · Post by **SaiK** » 18 Feb 2013 08:15

okay, so it is easy to blow up the rear of MKK by targeting the fins.

just getting a psychological advantage., actually it is a good thing to have. dunno if AMCA can have such arrangement, as it has move the additional weights when it yaws.

shiv · Post by **shiv** » 18 Feb 2013 08:28

Singha wrote:Read the wiki entry on su30mkk. Its mentioned 280kg of fuel tanks between the two rudders.

Between the rudders is different from inside the tailfins.

Indranil · Post by **Indranil** » 18 Feb 2013 11:00

gnair wrote: All trailing edges are sharp aren't they. They usually end as a part of the airfoil. Whether it is the stabilizer or the wing, they end with a very blade like form. I haven't seen anything out there that has a thick, blunt sort of cut-off. The only one I've heard about recently with a thicker, blunt cut off, is a new design they've incorporated in the PC-12NG, with their vertical stabilizer trim tab. Apparently it helps with adverse-yaw, and better deflection during the take off regime. PC-12's are centrifugal single engine turbines with a large prop, and the design will have to deal with that fact of life, despite the slap-on vortex generators placed along various critical areas of the air flow.

I was speaking of the wing tips. Not the trailing edges. I know what an aerofoil looks like

.

OT
Also, a blunt trailing is not as uncommon as you think. Infact it is used on both commercial and military planes.

A blunt trailing edge is used for higher efficiency and better control. In very layman's terms, this is because in a conventional aerofoil, the airstream from the top and bottom of the airofoil have to join at exactly the trailing edge. This does not happen in practice because the air are flowing in different angles. This leads to flow separation before the trailing edge and hence variable control. So by using a blunt trailing edge, you give a small area behind the edge where the flows can join and the flow does not separate before the trailing edge. It is also easier to build and structurally more sound.

SaiK · Post by **SaiK** » 20 Feb 2013 08:12

http://www.spsaviation.net/exclusive/?i ... tion-Dream
The obvious evolutions are clear: low-observable shape and airframe materials, extensive use of carbon composites, internal weapons bays, low bypass low-emission engines, modular internals, etc. The deeper you go, the more complicated and revolutionary the plans actually become.

Scientists will be working towards getting the mechanical gyros and accelerometers, standard on the Tejas, to evolve on the AMCA into fibre-optic gyros, ring laser gyros and MEMS gyros.

AMCA proposes to sport a distributed architecture with smart sub-systems.

Data communications on the AMCA’s processing modules will be through a high-speed fibre channel bus, IEEE-1394BSTD. The connectivities will be switched by means of a multiport switching matrix, with data speeds of 400 MB/second.

AMCA is almost certain to have integrated radio naviation systems, where all burdens earlier borne by analogue circuits will be carried out by digital processors.

AMCA commander will have the ability to plan attack strategies, avoidance tactics, retreat strategies and evasive strategies for himself and his partners in the air

SaiK · Post by **SaiK** » 20 Feb 2013 08:50

from the global review blog :
http://3.bp.blogspot.com/-Se8AtEJSl6I/U ... 289%29.jpg
Vamana Garuda

http://2.bp.blogspot.com/-5vVHicCGeac/U ... 5%2529.jpg
Air superiority config

http://3.bp.blogspot.com/-61jO6zx4gQ4/U ... 6%2529.jpg
SEAD

http://2.bp.blogspot.com/-ynFiuelGYCY/U ... 7%2529.jpg
Max external load

http://1.bp.blogspot.com/-zIPlHdzGH64/U ... 4%2529.jpg
General Char

chiru · Post by **chiru** » 20 Feb 2013 08:52

gnair wrote:Two things wished for the MCA that may be futuristic in value are:
1) If the vertical stabilizer is the size that it is, then every opportunity should be taken to fill it up with fuel, to optimize on endurance

when i posed the question - why are you not considering all moving V. stabilizer? to a high ranking gentleman at the ADA stall he said the same
1)they have some material constraints for those kind of loads &
2)they want to have fuel tanks in them

gnair · Post by **gnair** » 20 Feb 2013 09:27

chiru wrote:Two things wished for the MCA that may be futuristic in value are:
1) If the vertical stabilizer is the size that it is, then every opportunity should be taken to fill it up with fuel, to optimize on endurance

when i posed the question - why are you not considering all moving V. stabilizer? to a high ranking gentleman at the ADA stall he said the same
1)they have some material constraints for those kind of loads &
2)they want to have fuel tanks in them

Thanks for the feedback there Chiru.
A stuck servo motor in an all-moving V.stab may mean abandoning ship. Where as in the traditional lay out, there may be half a chance, with one rudder providing adequate yaw, to get home. (assuming that all control surfaces are electric driven for the MCA)

member_20296 · Post by **member_20296** » 20 Feb 2013 09:53

It might look a dumb question but wanted to know, what will be effects on a fighter plane if its wing edges on side and behind are jagged like eagle wings ? Will it give higher agility ?

SaiK · Post by **SaiK** » 20 Feb 2013 10:24

if it can be a controllable slat, yes. i am sure what triggered you that thought.. must be the vamana garuda one.

member_20296 · Post by **member_20296** » 20 Feb 2013 10:35

That's True SaiK my friend

lot to learn from nature

SivaVijay · Post by **SivaVijay** » 20 Feb 2013 10:59

^ The global review blog... Is that a fan boy wet dream or does it have any grain of truth to it? The last image says supercruise at max speed :O

Indranil · Post by **Indranil** » 20 Feb 2013 11:03

Raghuraj wrote:It might look a dumb question but wanted to know, what will be effects on a fighter plane if its wing edges on side and behind are jagged like eagle wings ? Will it give higher agility ?

No. They are used by birds to improve lift and lower drag by reducing wing tip vortices. In principle they are the same as the wingtip fences, blended winglets or the raked wingtips in the commercial jets, gliders etc. When you start to go transonic or higher speeds, the airflow changes and these wingtip devices are not as effective anymore.

Indranil · Post by **Indranil** » 20 Feb 2013 11:05

SaiK wrote:from the global review blog :
http://3.bp.blogspot.com/-Se8AtEJSl6I/U ... 289%29.jpg
Vamana Garuda

http://2.bp.blogspot.com/-5vVHicCGeac/U ... 5%2529.jpg
Air superiority config

http://3.bp.blogspot.com/-61jO6zx4gQ4/U ... 6%2529.jpg
SEAD

http://2.bp.blogspot.com/-ynFiuelGYCY/U ... 7%2529.jpg
Max external load

http://1.bp.blogspot.com/-zIPlHdzGH64/U ... 4%2529.jpg
General Char

This is fanboy stuff. So take this with a pinch of salt.

The youtube video that this is derived from said that a lot of attention was paid to detail. But frankly, I don't agree with them.

Singha · Post by **Singha** » 20 Feb 2013 11:06

shiv wrote:
Singha wrote:Read the wiki entry on su30mkk. Its mentioned 280kg of fuel tanks between the two rudders.
Between the rudders is different from inside the tailfins.

you have not read the wiki entry.

shiv · Post by **shiv** » 20 Feb 2013 14:34

Singha wrote: you have not read the wiki entry.

I have read it now. The fuel is stated to be inside the rudders, not between them. Since there are two tailfins I thought "between the rudders" is the huge space between them where the tail end of the fuselage offers a potential space for fuel.

The Wiki entry is ambiguous, because technically the "rudder" is the hinged movable airfoil at the back of the tailfin. I can understand the tailfin having integral tanks but not the rudder. It would be like having tanks in flaps or ailerons as opposed to integral wing tanks

Lalmohan · Post by **Lalmohan** » 20 Feb 2013 16:59

you also wouldn't want a fuel line coming out of a moving part

SaiK · Post by **SaiK** » 20 Feb 2013 19:39

http://forums.bharat-rakshak.com/postin ... &p=1413473

can that emphasize that it is not a low-bypass that is the problem, and as discussed by a few here?

shiv · Post by **shiv** » 21 Feb 2013 06:18

F-22 tailfins look as broad (and silly to my ignorant eyes) as AMCA model
http://www.youtube.com/watch?feature=pl ... aB5bIdksi8

vina · Post by **vina** » 21 Feb 2013 11:47

shiv wrote:F-22 tailfins look as broad (and silly to my ignorant eyes) as AMCA model
http://www.youtube.com/watch?feature=pl ... aB5bIdksi8

Every numbskull who dumps on the LCA program has to be forced to look at this video atleast 20 times.
If folks who basically invented FBW and implemented in a couple of dozens of airframes before this, can go and crash a plane like that with pilot induced oscillations (not to talk of Gripen crashes with a proven ready made FCS from the F-16, the Eurfighter crashes etc), and put that in perspective the LCA program and what a bunch of lowly dhoti clad SDRE scientists and engineers have managed to do in FBW/FCS, especially when they are doing it for the very first time, it puts everything in perspective.

member_20292 · Post by **member_20292** » 21 Feb 2013 13:14

^^^^

and I don't recollect any of these videos coming up about the LCA Saar.

Kudos...Indian scientific research people. Bravo.

shiv · Post by **shiv** » 21 Feb 2013 14:34

vina wrote: crash a plane like that with pilot induced oscillations (not to talk of Gripen crashes with a proven ready made FCS from the F-16, the Eurfighter crashes etc),

http://www.youtube.com/watch?v=k6yVU_yYtEc