AMCA - Advanced Medium Combat Aircraft (HAL)

[ersakthivel]

I have always been amused by the design philosophy of creating an unstable ac and than adding more and more contol surfaces to just to make it fly. Addition of these control surfaces add weight and consequently results in degradation of performance besides making the ac heavier. All you aerodynamics experts must remember the qudraple rule for designing an ac and need to know few basic facts about aerodynamics.

The vetted area of an ac and its wings matters the most for high speed ac as skin friction drag increases with increase in size and speed.
The design of airfoil (wing Planform) has direct bearing on the overall weight of the ac as the weight of the undercart increases and can be anywhere from 2.5% of MTOW to 4.5% of MTOW of the ac. This is what made LCA go beyond the design OEW. Infact the weight of undercart for a carrier based ac is 25% higher than a shore based ac. The CLmax of an airfoil is directly proportional to its sweep angle.
Now, we started LCA project with an aim to have a small light fighter. We used F-16XL as a baseline. The net result is that we have an ac which flies better than M2K but has control surfaces much bigger than that of M2k resulting in overall degradation of load carrying ability and also problems with C of P control. The control deflection for a tail less RSS delta has these problems.
Using movable LEVCONS in LCA will only add to these problems. My best suggestion is to make LCA positively stable design with maneuover margins kept between 5% to 1% like F-16 blk-52. AND ADD CRUCIFORM TAIL TO IT AS IT ALREADY HAS A FLAT RUDDER.

Mirage-2000 is the fighter that started the original RSS , low wing loading airframe design concepts of the tailless large wing weight , wing area delta.

The Mirage 2000 features a low-set thin delta wing with cambered section, 58 degrees leading-edge sweep and moderately blended root; area-ruled; two small canard wings, fixed, placed just behind the air intakes. The flight controls on the wings are: four elevons (+15/−30°), four slats.

In the 1982 summer, at the Farnborough Airshow, this machine displayed not only excellent handling capabilities, but also a full control at 204 km/h and 26 degree angle of attack.

This was totally unexpected in a delta-wing fighter, and proved how CCD controls were capable of overcoming the delta wing shortcomings related to poor low-speed control, while retaining the advantages, such as low-drag, low radar cross section, ideal high speed aerodynamics and simplicity, provided by the absence of horizontal tail surfaces


Its neutral point is in front of its center of gravity, giving the fighter relaxed stability to enhance maneuverability. It incorporated negative stability and fly-by-wire controls with four analog computers. An airbrake is fitted above and below each wing in an arrangement very similar to that of the Mirage III. A noticeably taller tailfin allows the pilot to retain control at higher angles of attack, assisted by the small strakes mounted along each air intake.

The mirage-2000 has low enough thrust line compared to CG., still it's designers went for RSS. WHY?

Doing away with the tail also results in a reduction of control surfaces and associated hydraulic loads for it.

F-16 blk 52 onwards became-------- maneuover margins kept between 5% to 1%----- as it bulged with repeated additions of hardware after every upgrades. So it may not be a good solution for tejas as it faces no such restrictions.

 

[lookieloo]

Why is everyone always talking about the LCA over here? Every time I see this thread getting bumped, I click hoping to see a new development on AMCA, only to get Rickrolled with more Tejas arguments.

 

[ersakthivel]

Why is everyone always talking about the LCA over here? Every time I see this thread getting bumped, I click hoping to see a new development on AMCA, only to get Rickrolled with more Tejas arguments.

You can always find that beating down LCA is a common agenda across all the threads here.Whether you go to Dassault RAFALE thread or PAKFA thread or J-20 thread or pretty much any other thread, you can always see people finding fault with LCA tejas.

So I reply to them in the vain hope that people won't do it further on any other thread.

 

[arnabmit]

AMCA Project on hold

Due to prolonged delays in the ambitious Light Combat Aircraft (LCA) project, the future plans for an Advanced Medium Combat Aircraft (AMCA) for the Indian Air Force (IAF) has been shelved temporarily.

The 'Tejas' LCA has taken 30 years already, at an escalated project cost of Rs 5,489 crore. Since the LCA project was sanctioned in 1983 at a cost of Rs 560 crore, the time overrun has resulted in a 10-fold increase in the project cost.

" The MoD has "put on hold" the AMCA project that is being spearheaded by Defence Research and Development Organisation's (DRDO) Aeronautical Development Agency (ADA). This decision has been taken in an effort to help ADA to focus all its energies to concentrate on completing the much-delayed LCA project," sources in MoD told FE.

"Since most of the capabilities of AMCA are expected to met by the 126 Medium Multi Role Combat Aircraft (MMRCA) and the Fifth Generation Fighter Aircraft (FGFA) in collaboration with Russia, the revival of the AMCA will be a well thought-out one," sources said.

The plan is to ensure that ADA meets its schedule of obtaining the Initial Operational Clearance (IOC) before July this year so that the IAF can take it for a spin. "However, LCA still lacks certain critical capabilities, including a reliable radar, and is deficient in at least 100 technical parameters, due to which it could take till December this year or early next year before it is ready for the IOC," sources added.

Says chief of IAF Air Chief Marshal NAK Browne: "The Mark-II version of the LCA is still four to five years away. The IAF has looked at 40 of the LCA Mark-I variant on the condition that Mark-II will have a more powerful engine. A contract has been signed between the DRDO and GE for this. That programme is still four to five years away."

At present, the IAF has placed an order for 40 LCAs Mk1 to raise two squadrons by 2016-17 with HAL which is the nodal agency for production of Tejas. But these will be delivered with the American General Electric F404 engines which provide only 80 Kilo Newton power.

Guess its official now...

 

[ersakthivel]

AMCA Project on hold



Guess its official now...

there is nothing official about reports that quote ,"unnamed defence ministry officials ".

In fact there are legion of false reports like this quoting unnamed guardian angels, which were proved not worth the paper they were written on.

No credible official will soil his name with such reporters.

AMCA is in design stage with funds released already. No manufacturing metal cut work is going to happen for the next two years atleast , So there is no way of authenticating whether work is being done or put on hold as mentioned in the "glorious unnamed official source report". Because most of the work now will be in simulation software and wind tunnel work. production activity will start only years later after all the design configuration is refined. So how can the reporter confirm that all this design works being stalled?

AMCA ASR definition itself was a ten year delayed enterprise. SO does the reporter wants it to be extended it to 12 year delay. The design team working on MK-2 improvements over mk-1 and the AMCA will be enirely different at different stage of their work.

You can judge the quality of report by the sentence that most of the capabilities of the AMCA will be delivered by the present MMRCA winner!!!!!!!!!!!

I wonder which capability? 5th gen stealth RCS and internal weapon bays?

Even the 5th gen FGFA is going to have an RCS much bigger than the AMCA. Chances are the FGFA will have far worse RCS than the controversial F-35.SO priority for AMCA which has the specified 5th gen RCS is more important than the so called delays of Tejas.

it has been repeated many times tejas has just 5 or 7 years excess development timeframe compared to RAFALE or TYPHOOON which also have similar tech levels as composites , Relaxed static stability FBW system and avionics.

SO the report is false on all the facts.

 

[santosh_g]

You can judge the quality of report by the sentence that most of the capabilities of the AMCA will be delivered by the present MMRCA winner!!!!!!!!!!!
I wonder which capability? 5th gen stealth RCS and internal weapon bays?

it seems reporter/unnamed defence ministry officials donno anything about 5th gen fighters. plus we will get screwed big time in future if ADA stops working on AMCA. After all we really cant depend on PAKFA completely and we can't predict how US behaves at times. They might sell F-35 to Paki's after ten years(and russians might sell PAKFA to china so that they can copy it and mass produce it ).better to get ready with much stealthier fighter than PAKFA n F-35 :thumb:

 

[Decklander]

@ersakthivel, There is a huge difference in having a low thrustline and a thrustline which passes below the CG of the ac. Just to explain you better,
have you ever played pool? What happens when you hit the ball on the centre, when you hit it on top and when you hit it on bottom?
Please explain and than I won't need to explain anything to you.

 

[ersakthivel]

@ersakthivel, There is a huge difference in having a low thrustline and a thrustline which passes below the CG of the ac. Just to explain you better,
have you ever played pool? What happens when you hit the ball on the centre, when you hit it on top and when you hit it on bottom?
Please explain and than I won't need to explain anything to you.

All low thrust lines simply has to pass below the Cg is my opinion.
There is no way for the thrust line of Mirage -2000 to pass on or above the CG.
It has to go below the CG.
Still Mirage went for CG behind CL RSS config. Why?

Well , when the ball is hit at the bottom the force passes through different vector. It is quite a simple thing.And the ball has the tendency to move in upward direction.


But that does not prevent the Cg which is in front of the Center of lift(in non- RSS configuration) from applying a nose down momentum opposing the effort of having a thrust line below CG config alone.



But Mirage also has a thrust line below the CG in the same way as F-16 XL is my opinion.

Is it right or wrong?

if it is right then why it went for the same RSS airframe opposed to simple thrust line which passes below the CG arrangement?

 

[binayak95]

Due to prolonged delays in the ambitious Light Combat Aircraft (LCA) project, the future plans for an Advanced Medium Combat Aircraft (AMCA) for the Indian Air Force (IAF) has been shelved temporarily.

The 'Tejas' LCA has taken 30 years already, at an escalated project cost of Rs 5,489 crore. Since the LCA project was sanctioned in 1983 at a cost of Rs 560 crore, the time overrun has resulted in a 10-fold increase in the project cost.

" The MoD has "put on hold" the AMCA project that is being spearheaded by Defence Research and Development Organisation's (DRDO) Aeronautical Development Agency (ADA). This decision has been taken in an effort to help ADA to focus all its energies to concentrate on completing the much-delayed LCA project," sources in MoD told FE.

"Since most of the capabilities of AMCA are expected to met by the 126 Medium Multi Role Combat Aircraft (MMRCA) and the Fifth Generation Fighter Aircraft (FGFA) in collaboration with Russia, the revival of the AMCA will be a well thought-out one," sources said.

The plan is to ensure that ADA meets its schedule of obtaining the Initial Operational Clearance (IOC) before July this year so that the IAF can take it for a spin. "However, LCA still lacks certain critical capabilities, including a reliable radar, and is deficient in at least 100 technical parameters, due to which it could take till December this year or early next year before it is ready for the IOC," sources added.

Says chief of IAF Air Chief Marshal NAK Browne: "The Mark-II version of the LCA is still four to five years away. The IAF has looked at 40 of the LCA Mark-I variant on the condition that Mark-II will have a more powerful engine. A contract has been signed between the DRDO and GE for this. That programme is still four to five years away."

 

[Decklander]

All low thrust lines simply has to pass below the Cg is my opinion.
There is no way for the thrust line of Mirage -2000 to pass on or above the CG.
It has to go below the CG.
Still Mirage went for CG behind CL RSS config. Why?

Well , when the ball is hit at the bottom the force passes through different vector. It is quite a simple thing.And the ball has the tendency to move in upward direction.


But that does not prevent the Cg which is in front of the Center of lift(in non- RSS configuration) from applying a nose down momentum opposing the effort of having a thrust line below CG config alone.



But Mirage also has a thrust line below the CG in the same way as F-16 XL is my opinion.
Is it right or wrong?

if it is right then why it went for the same RSS airframe opposed to simple thrust line which passes below the CG arrangement?

You go into combat with full bore. If you have CG ahead of the CP for a stable ac, the thrustline below the CG adds to the pitch up movement of the nose and gives you same kind of pitch up rate which you get in a RSS ac. Just calculate what will be the pitch up thrust added to the tail plane authority for an engine generating 98KN thrust with a downward tilt of its thrustline of 3*.
You will need to multiply the Sin3* with the thrust available.

 

[ersakthivel]

You go into combat with full bore. If you have CG ahead of the CP for a stable ac, the thrustline below the CG adds to the pitch up movement of the nose and gives you same kind of pitch up rate which you get in a RSS ac. Just calculate what will be the pitch up thrust added to the tail plane authority for an engine generating 98KN thrust with a downward tilt of its thrustline of 3*.
You will need to multiply the Sin3* with the thrust available.

The amount of lift produced is directly proportional to the wing area, and the engine thrust available for the weight of the fighter,
It won't change with thrust line arrangement alone.

The calculation you use is used to get the distance, The lift force won't change by SIn3* multiples is my opinion.

The 98 Kn thrust will generate only a fixed amount of lift, whatever be the position of thrust line with respect to CG.

Unless we have Cg behind the CL there (i.e RSS )is no way a simple Thrust line below the CG arrangement alone will counteract the nose down momentum of CG infront.

What is more important is the position of CL wrt to Cg not just that of thrust line.

You are yet to answer the question whether the Mirage-2000 's thrust line lies below the Cg or not?

Why I am asking it is the older mirage -lll were positive static stability platforms with the same thrust line below CG arrangement you are referring to. The Mirage-2000(RSS fighter with Cg behind the CL) evolved from the older mirage-lll for reasons of better maneuverability.

The following is the picture of MIRAGE-III , it certainly has thrustline below the CG as much as F-16XL has, you can't deny that . it is obvious. But it has positive static stability meaning the CL is behind the CG leading to nose down momentum ,

But Mirage-2000 below is an improvement over the MIRAGE-lll with the same wing arrangement resulting in lower thrust line below the CG, but with one major difference RSS(CL infront of the CG , giving a nose up momentum, same as that of tejas)

 

[Decklander]

The 98 Kn thrust will generate only a fixed amount of lift, whatever be the position of thrust line with respect to CG.Unless we have Cg behind the CL there is no way a simple Thrust line below the CG arrangement alone will counteract the nose down momentum of CG infront. What is more important is the position of CL wrt to Cg not just that of thrust line.
You are yet to answer the question whether the Mirage-2000 's thrust line lies below the Cg or not?
Why i am asking it is the older mirage -lll were positive static stability platforms with the same thrust line below CG arrangement you are referring to. The Mirage-2000(RSS fighter with Cg behind the CL) evolved from the older mirage-lll for reasons of better maneuverability.

I rest my case as you seem to have bcum dogmatic with hardly any knowledge of ac design stability. You are stuck on RSS without realising that the trend now has gone back to stable design as the need for ITR and STR are no more a factor with advent of all aspect missiles which like MICA can shoot down a target 180* behind while the ac is flying straight without the need to turn. You probably have not even heard of HMD guidance wherein the ac need not even use its ITR or STR.
Buddy, you are still in 2013 BC while the aircombat has moved to 2013 AD.

 

[Decklander]

The 98 Kn thrust will generate only a fixed amount of lift, whatever be the position of thrust line with respect to CG.Unless we have Cg behind the CL there is no way a simple Thrust line below the CG arrangement alone will counteract the nose down momentum of CG infront. What is more important is the position of CL wrt to Cg not just that of thrust line.
You are yet to answer the question whether the Mirage-2000 's thrust line lies below the Cg or not?
Why i am asking it is the older mirage -lll were positive static stability platforms with the same thrust line below CG arrangement you are referring to. The Mirage-2000(RSS fighter with Cg behind the CL) evolved from the older mirage-lll for reasons of better maneuverability.

The following is the picture of MIRAGE-III , it certainly has thrustline below the CG as much as F-16XL has, you can't deny that . it is obvious. But it has positive static stability meaning the CL is behind the CG leading to nose down momentum ,

But Mirage-2000 below is an improvement over the MIRAGE-lll with the same wing arrangement resulting in lower thrust line below the CG, but with one major difference RSS(CL infront of the CG , giving a nose up momentum, same as that of tejas)

Bro please do not teach me all about stability. I have flown ac which was not a RSS ac but an ac which used to transition from a basic stable to neutral to completely negative called the SEA HARRIER. Keep all this stupidity of M2K to yourself.

 

[Decklander]

You must learn to answer questions as you love to throw them up. Please reply to my last query.

 

[ersakthivel]

You must learn to answer questions as you love to throw them up. Please reply to my last query.

thrust is a physical force which generates lift. But Sin3* multiples relate to distance not force. How do you mingle both up?

 

[ersakthivel]

Bro please do not teach me all about stability. I have flown ac which was not a RSS ac but an ac which used to transition from a basic stable to neutral to completely negative called the SEA HARRIER. Keep all this stupidity of M2K to yourself.

The sea harrier is a sub sonic carrier based positive stability platform, What is it going to contribute to a discussion on thrust line and RSS airframe?
So you are not going to answer any questions regarding MIRAGE-lll vs MIRAGE-2000 and F-16 XL.
Doesn't matter.
When does Sea harrier achieve negative stability?

 

[Decklander]

The moment you rotate the nozzles for take off, the ac bcums negatively stable and also when you rotate nozzles to come for landing the ac is negatively stable. We take off and land with negative stability in all configurations except normal take off and landing which we very rarely do. I ejected from IN-619 seaharrier on 6Th june 1993 as the reaction control system failed during a 100/65 T/O. The ac departed completely.

 

[ersakthivel]

The moment you rotate the nozzles for take off, the ac bcums negatively stable and also when you rotate nozzles to come for landing the ac is negatively stable. We take off and land with negative stability in all configurations except normal take off and landing which we very rarely do. I ejected from IN-619 seaharrier on 6Th june 1993 as the reaction control system failed during a 100/65 T/O. The ac departed completely.

Are these flight profiles simply near stall or relaxed static stability?

 

[Decklander]

Sea Harrier has nothing like stall if using nozzles. We are certified to fly backwards at sppeds of upto 40Kts. Yes, you read it correct, FLY BACKWARDS SOMETHING WHICH EVEN HELOS ARE NOT CERTIFIED FOR. We cud generate much higher pitch up rates than RSS ac by use of Nozzles.

 

[ersakthivel]

RSS fighters pitch up with negative stability while their wings are fully aerodynamically efficient,
in close combat maneuvers at corner speeds, not while flying backwards.
Generating pitch up rates using nozzles(or just with thrust line below the Cg) is one thing ,
and sustaining it in close combat using the RSS enabled instability with CG behind the CL and all the while maintaining corner speeds is another thing.