ADA Tejas Mark-II/Medium Weight Fighter

[ersakthivel]

Slightly Older but Interesting interview with Air Marshal Philip Rajkumar (retd)
FORCE Nov 2010

'There Will Be Design Changes in LCA Mk-2 and all Design Changes will Lead to a Weight Penalty'
Air Marshal Philip Rajkumar (retd)

In your opinion what are the shortfalls the LCA could be facing currently because of an underpowered engine?

Lack of engine power leads to lack of performance. The main shortcoming would probably be in manoeuvring flight and the ability to take off with the required load from runways in hot and high conditions. There will be increase in time to climb to height and it won't accelerate as fast. So the Indian Air Force (IAF) in its wisdom has said that they are not happy with the performance of the LCA with its current engine. One of the points mentioned is that the sustained turn rate has been lower than specified. One must understand that the performance parameters laid down in the Air Staff Requirement (ASR) have been arrived after a lot of debate in Air Headquarters. I don't understand the argument of reducing the payload to meet performance. The IAF requires a certain level of performance to be delivered for the payload that is being asked for. Engine power is important and having arrived at the conclusion that thrust on the current GE-404 engine is insufficient, it is the GE-F-414 that has been chosen.

Now thrust is proportional to fuel consumption and increased thrust will lead to increased fuel consumption which will have a bearing on mission performance. Having a more powerful engine does not automatically increase performance.

What changes will the choice of a new engine require for the LCA Mk-2?

With regards to the LCA Mk-2 there will be design changes and all design changes will lead to a weight penalty. The outcome of this design exercise that ADA is undertaking on the LCA Mk-2 is yet to be seen. The LCA Mk-2 will have a slighter longer fuselage and may carry more fuel as well. Will the weight go up, will they add more fuel, will the aircraft be able to offer the performance demanded by the IAF with an engine offering more thrust and higher fuel consumption are questions I cannot answer, as these details have not been made public. We could however use this opportunity to lengthen the fuselage, look at the wave drag to improve aerodynamics, put a wider chord on the wings to generate more lift, etc. However, this would then essentially result in a new aircraft but it will be a more capable aircraft and this is a good opportunity to do so. The slightly larger LCA Mk-2 can also include essential operational equipment without which the LCA Mk-2 will not be able to fulfill its operational role. These changes would lead to increase in the All Up Weight (AUW) and result in the LCA Mk-2 being different from Mk-1 by 25 per cent.

By when do you see these changes being completed and the LCA Mk-2 taking to the air with the GE-F414 engine?

I will be extremely happy if the LCA Mk-2 flies by 2015 and all these changes are completed in the next five years. If they are changes in chord of wing and length of fuselage, then the FCS will also need changes. All these would again require flight testing, though not as extensive as that of the LCA Mk-1. This will require a flight test schedule that will take 2 to 2.5 years in my opinion. The LCA Mk-2 would then attain operational capability by 2018 and enter operational service with the IAF by 2020. If we can achieve this, it would be commendable.

Is it also time to review the role of the LCA in IAF, considering it will be operating next to the Su 30 MKI and MMRCA followed by the FGFA?

The LCA will be a frontline fighter capable of protecting itself and carrying out a useful strike role. But its theatre of operations will depend on the threat levels it will face. If we develop the LCA Mk-2 with the necessary Electronic Warfare (EW) and countermeasure dispensing capability, I don't see why it cannot be used in any theatre of war. Given our geographical size and the need to face two fronts, we still need numbers with the IAF talking about 40 squadrons. The LCA will be the 3rd tier after the Su-30 MKI/FGFA and MMRCA. The IAF says that they will take 40 LCA Mk-1 aircraft and those aircraft are important for the simple reason that it will enable both ADA and HAL to obtain spares consumption data as to how many maintenance hours are required per flying hour. This data can be accumulated by using the LCA Mk-1 over this decade to put product support in place. The hope is that by the time the LCA Mk-2 is ready to enter service; all these problems would have been ironed out. The LCA Mk-1 could also be used to create an Operational Conversion Unit (OCU) if required to feed pilots into the system as the IAF will be inducting large numbers of aircraft over the next two decades. The LCA Mk-1 will serve the IAF extremely well for at least the next three decades.

What needs to be done to improve performance and reduce the weight of the LCA?

The way to go about increasing the LCA's performance is by reducing its drag and weight including structural weight but this is a long drawn out exercise. The entire aircraft has to be instrumented so we can measure the loads existing in flight and then compare the data with design loads that have been catered for. A particular part of the structure could have been made too strong and another part too weak. So we have to perform a structural optimisation exercise that usually results in reduction in weight. The aerodynamic optimisation will lead to some configuration changes. Unfortunately our aeronautical institutions from the days of the HT-2 have never undertaken the task of measuring the aerodynamic loads during flight and optimising the structure. We did not do it for the 'Marut' or the 'Kiran'. I have always maintained that performing a structural optimisation exercise is the way to go. I am told that it is a time consuming exercise, but we have to start from somewhere. There is no easy way out. You can also reduce weight by looking at the Line Replaceable Units (LCA), Head-Up Displays (HUD), and Mission Computers etc.

Will the selection of the GE-F414 benefit any of the competitors in the MMRCA contract for the IAF?

The aircraft using the GE 414 engine in the MMRCA competition are the F/A 18 Super Hornet and the Gripen. If they factor in this development it will definitely benefit as the cost of acquisition of these aircraft would come down a little bit. Certainly if the GE 414 is made in India it will bring down the cost of that acquisition, maybe by about 10 per cent.

Do you see the Snecma-Kaveri engine entering service in the LCA?

I definitely do not see the Snecma-Kaveri engine powering either the LCA Mk-1 or Mk-2. However LCA Mk-1 will be used as a flying test bed to put the engine through its paces, before it enters service. However we have to develop the Snecma-Kaveri engine because we cannot call ourselves an aeronautical power in any sense of the word unless we have our own engine. As we speak the Kaveri engine is getting ready to fly in Russia which will give us an enormous amount of confidence. After the 100 hour programme we will have a significant amount of data. With the French coming in the Kaveri will now become a reality and it will get test flown on the LCA airframe at some point of time. My estimate is that this will happen sometime between 2015 and 2018, once we sign on the dotted line. That is the engine that the MCA will be designed around and it will power this aircraft.

What needs to be done to ensure that MCA flies with an Indian engine?

The first thing that needs to be done is to complete the 100 hour Flying Test Bed (FTB) programme on the existing Kaveri engine. That is an essential pre condition. The data generated from the 100 hour FTB programme, will enable us to communicate much better with the French as we would have flown an engine, compared to the static test beds so far. We will also be able to extract more out of the French if this is done. The next is to develop this engine as soon as possible and put this in a flying test bed and keep it ready by the time the MCA gets designed. If we get our sums right then we can fly the MCA with an Indian engine between 2020 and 2022. This will also require a large number of designers and currently there is a serious manpower constraint in the design bureaus of HAL, ADA and elsewhere. You just have to look at the number of projects ongoing currently, HAL is now developing the LCH, LUH another helicopter in the 10 tonne class followed by programmes for the LCA, MCA, FGFA, Multirole Transport Aircraft (MTA), Intermediate Jet Trainer (IJT), Hindustan Turboprop Trainer (HTT-40) followed by upgrades for Jaguar, Mig-29, Mirage 2000, etc. All this, requires a large number of designers working concurrently as these programmes are being run side by side.

You should also factor in the recomendations by CEMILAC ,

http://drdo.gov.in/drdo/pub/dss/2009/main/2-CEMILAC.pdf

Converting metal components into composite: Weight reduction
is an important activity in an aircraft program to improve
the performance. Use of high performance composite material
can considerably reduce the weight of the components
and preserving the structural integrity. The airframe of
Tejas has already undergone one cycle of weight reduction
prior to Prototype Vehicle series, which resulted in a weight
saving around 350 Kg. It is felt that some of the components
like slat doors, casing & mounting of LRUs and rear fuselage
bulkheads and pylons can be converted into composite.
This will give further weight reduction.
Co-cured co-bonded wing: LCA wing components have
been manufactured separately and joined together using
rivets, fastener and sealant. In the proposed co-cured cobonded wing, the bottom skin, ribs and spars are cured
together. This has advantage from reduced part count as
well as weight saving. The weight saving is mainly due
to the eliminations of sealents and fasteners associated
components. Further, the wing is expected to have improved
s

which details substituting composites for engine mountings that will reduce further weight and the ADA chief's interview that percentage of composites in LCA mk-2 will go up to 60 percent. SO weight reduction efforts to counter the additional fuselage length and fuel load is already initiated .ADA chief himself has said that LCA mk-2 will exceed mk-1 by 40 percent in performance specs. only time will tell.

Some one needs to put what is the original ASR of LCA mk-1 . IS there any document pertaining to that?As far as I know the following is the most authoritative document on LCA TEJAS mk-1's specs from the following link,


http://www.tejas.gov.in/featured_articles/air_marshal_msd_wollen/page02.html

The LCA is tailless with a double-sweep delta wing. Its wing span is 8.2 m, length 13.2 m, height 4.4 m. TOW clean 8.500 kg, MTOW 12500kg. It will be super-sonic at all altitudes, max speed of M 1.5 at the tropopause. Specific excess power and g-over load data has not been published. Maximum sustained rate of turn will be 17 deg per sec and maximum attainable 30 deg per sec. Funds have been sanctioned for a Naval LCA. PD and studies in critical technology areas have commenced. The aircraft will be powered by a Kaveri engine (more information follows) and is to operate from the Indian Navy's Air Defence Ship, under construction. Launch speed over a 12 deg ramp is 100 kts; recovery speed during a no flare deck landing, using arrester gear, is 120 kts. Take off mass 13 tonne, recovery mass 10 tonne. Most stringent requirements are that the airframe will be modified: nose droop to provide improved view during landing approach; wing leading edge vortexes (LEVCON) to increase lift during approach and strengthened undercarriage. Nose wheel steering will be powered for deck maneuverability.

To date it has done mach 1.6 at high altitude and has achieved the same top speed of MIG-29 and SUKHOI in indian skies by going past the 1350 km per hour mark in hot skies in GOA, in a powerless dive from 4 km to sea level in a flutter test. SO wave drag did not stop it from achieving it's sea level top speed either.So as per the following link from CEMILAC

http://drdo.gov.in/drdo/pub/dss/2009/main/2-CEMILAC.pdf

One of the major out come of sea level trial of Tejas
is that the drag of the aircraft is high such that the aircraft
could not reach the supersonic Mach number at sea level.
The components contributing for the maximum drag rise
has been identified and improvement methods were worked
on.

CEMILAC recommended nose cone plug extension as a remedy for smoothening the sudden increase in cross section from x=5000 mm to x=6000 mm along fuselage. But surely there are other ways that can be used to overcome this problem by gradually increasing the cross section in place of sudden increase, which would not be visible to naked eye,without recourse to nose plug extension

So by attaining the same top speed in Indian skies as that of SU-30 MKi and Mig-29 , I suppose these wave drag problem has been overcome ,

or if you have opinion to the contrary you can please post

Sure the longer length of MK-2 will lead to much better aerodynamic performance. But that doesnot preclude the possibility of Tejas mk-1 having resolved it's wave drag problem due to sudden increase in cross section from 5 meter to 6 meter mark along the fuselage.

which explicitly states that corrections are underway to reduce the wave drag , which means the wave drag problem has been overcome or how could Tejas mk-1 attain same speeds as MIG-29 and Sukhoi in Indian skies in GOA?


Also it has exceeded the 17 deg STR by performing a vertical loop in Aeroindia 2013 in 20 seconds same as RAFALE.It gives you a rough STR of 18 deg per sec.This 20 second loop is done well within the partially opened flight envelope with still 15 percent of the top performance soec yet to be tested.

The Max take off weight is 12 .5 ton as per MSD WOLLEN's article. Now even with the MTOW of 13.5 ton tejas mk-1 seems to have exceeded all the parameters laid down in that ASR means it is a credible achievement not a short fall in performance. Note this increase in weight of 1 ton is due to the higher weight higher launchin stress inducing longer range BVR requirements which were added to specs after the TD-1 flew.


the Tejas mk-1 now has the ability to fire any higher range BVR with this increased wing weight of 1 ton which was tagged later and still manages to surpass all the specs in the ASR with just 6G partially limited flight envelope means it has clearly gone past all the specs listed in the original ASR by fair margin. STR is obsolete in today's dogfight because of high off boresight HMD assisted WVR missiles. What is most important is having high ITR which is vital in missile dodging maneuvers and obtaining the first firing solution with quick nose pointing ability.
But tejas seems to have done well in this spec because it naturally has the lowest eingloading lower than the Mirage and higher TWR than mirgae.

So is there another revised IAf ASR present , whose conditions the LCA mk-1 cannot meet or what?

 

[ersakthivel]

Reign of Naval aviators

Other than the MIG-29s the Indian Navy has no alternatives in sight which has much higher RCS and dated design with no composites and very costly to buy and maintain if we take into account the lifecycle cost and import of spares along with constant upgrades all in foreign currency .That's why it is spending money on LCA mk-2.

But IAF has no need, and it has no concern about very costly imported fighters to buy and maintain if we take into account the lifecycle cost and import of spares along with constant upgrades all in foreign currency for almost the same operational capability if we take into account the increased performance of mk-2 .And their interests are always "well served " foreign fighters.That's why they are not shelling out even a nickel for tejas .becuase all of the excess expenditure for foreign fighters can be masked under the head national defence preparedness..

 

[Bhadra]

Let us test that machine over Depsang (DBO) ..if it fails scrap the whole thing..

 

[ersakthivel]

Tejas goes past speed of 1,350 kmph in tests : India, News - India Today

The aircraft went past its ultimate speed of 1,350 kmph on December 7 in Goan skies when it took off from Indian Navy?s INS Hansa base," Cmdr Rohit Varma, project director (flight test), National Flight Test Centre, told reporters here.
He said that this is the fastest speed ever achieved by an Indian made fighter aircraft.
The aircraft also passed flight flutter test after diving from four kilometres height and later taking off at 900 metres close to sea level.

 

[ersakthivel]

Let us test that machine over Depsang (DBO) ..if it fails scrap the whole thing..

After scrapping this machine which machine can deliver DBO to us , you are free to specify.....

 

[Austin]

To date it has done mach 1.6 at high altitude and has achieved the same top speed of MIG-29 and SUKHOI in indian skies by going past the 1350 km per hour mark in hot skies in GOA, in a powerless dive from 4 km to sea level in a flutter test. SO wave drag did not stop it from achieving it's sea level top speed either.So as per the following link from CEMILAC

Are you sure that Mig-29 and Su can do just Mach 1.6 ? Both aircraft have variable geometry intakes and can go well above Mach 2.

Tejas is restriced to M 1.6 as it has fixed intakes.

 

[Decklander]

If you do a bit of research on aircraft design for low weight and low drag plan forms, you will find that LCA is the worst design for a light weight fighter. Also the sweep angle of this ac is the main problem for it being over weight. A tailless delta with sweep angle of 53* is probably the worst design that one shud look to put on a carrier. Large sweep on a delta plan form needs higher and taller oleos for undercarriage to be able to land at AOA which they need. It also results in a higher weight of wing. The trapezoidal wing with leading edge sweep higher than rear edge sweep gives lightest wing with lowest drag and least possible movement of CofP with AOA and Mach no.

Also the best sweep angle for a fighter for carrier ops is between 40*-46*. Su-30, Mig-29, Rafale, F-18, F-14 & Su-33 have sweep angles within this limit. This sweep angle also results in need for shorter landing gears and low approach angles with far superior fwd visibility.
I have very serious doubts if we will ever have a full fledged carrier based LCA. We might have just 1-12 of them as trainers. N-LCA DESIGN IS AN UNFIT DESIGN FOR CARRIER OPERATIONS.

 

[Austin]

ersakthivel , Regarding Tejas Mk2 we need to wait and see till that fighter is in metal and flies and there is enough data on it , P Rajkumar is a old hat on Tejas so he knows the pro and cons when it comes to Tejas.

Right now the focus should be to get the IOC and FOC on Tejas Mk1 and see how it proceeds ......every one is keenly watching it.

 

[ersakthivel]

Are you sure that Mig-29 and Su can do just Mach 1.6 ? Both aircraft have variable geometry intakes and can go well above Mach 2.

Tejas is restriced to M 1.6 as it has fixed intakes.

I was referring to the top speeds at sea level.
It is a known fact that MIG-29, SUKHOI and LCA all have the same top speeds at sea level of around 1350 km per hr (around mach 1.1) in hot humid indian skies which does significantly reduces the top speed of fighters opposed to colder climes.

Not the top speeds at altitude ceiling. At service ceiling the LCA mk=1 is supposed to have a mach 1.8 top speed , present one demonstrated is mach 1.6.

The mig-29 and sukhoi have higher service ceiling where air speeds are naturally higher for the same aerodynamic contraption due to lower drag.But tejas has lower service ceiling.

The same type of inlet is being planed for Tejas mk-2 , whose top speed is stated to be mach 2 at service ceiling. So will ADA achieve the top speed of mach 2 for tejas mk-2 with the same inlet design with just 10 mm higher dia?

 

[Austin]

Never come across any official data that claims Top Speed at Mach 2 for Tejas Mk2 ....since it has fixed intake it will be around ~ M 1.6-1.8

If its Top Speed at sea level then yes the data is correct.

 

[ersakthivel]

If you do a bit of research on aircraft design for low weight and low drag plan forms, you will find that LCA is the worst design for a light weight fighter. Also the sweep angle of this ac is the main problem for it being over weight. A tailless delta with sweep angle of 53* is probably the worst design that one shud look to put on a carrier. Large sweep on a delta plan form needs higher and taller oleos for undercarriage to be able to land at AOA which they need. It also results in a higher weight of wing. The trapezoidal wing with leading edge sweep higher than rear edge sweep gives lightest wing with lowest drag and least possible movement of CofP with AOA and Mach no.

Also the best sweep angle for a fighter for carrier ops is between 40*-46*. Su-30, Mig-29, Rafale, F-18, F-14 & Su-33 have sweep angles within this limit. This sweep angle also results in need for shorter landing gears and low approach angles with far superior fwd visibility.
I have very serious doubts if we will ever have a full fledged carrier based LCA. We might have just 1-12 of them as trainers. N-LCA DESIGN IS AN UNFIT DESIGN FOR CARRIER OPERATIONS.

It has double delta with lesser sweep at the wing root and larger sweep later . This design's purpose is to delay the onset of flow separation vortices at the wing root during high AOA and lower speeds ,and to do away with some of the undesirable low altitude handling problems of pure deltas, it effectively combines some functions of canards with no force couplingcomplex handling issues relating to canards.

 

[Decklander]

It has double delta with lesser sweep at the wing root and larger sweep later . This design's purpose is to delay the onset of flow separation vortices at the wing root during high AOA and lower speeds ,and to do away with some of the undesirable low altitude handling problems of pure deltas, it effectively combines some functions of canards with no force couplingcomplex handling issues relating to canards.

I am very well aware of the complete design of LCA. Pls go thru the details of YF-23 also in your spare time. The effective sweep angle of a trapezoidal wing is the difference between leading edge sweep and trailing edge sweep. so A trapezoidal plan form with 42* LE sweep and 21* TE sweep will have same charactersticks which a wing with sweep angle of 21* will have.
My post was not about LCA as such but about it being used as a carrierborne fighter. It is no doubt a great design but IMHO, unfit for deck ops and ops from unprepared/grass strips.

 

[p2prada]

LCA wasn't designed for the carrier from the get-go.

I don't really know why the Navy was suddenly interested in the carrier. As a conversion unit or LIFT, Mk1 is more than enough for the job and that's what it will be used for. I don't really get the point of Mk2 when Mig-29Ks were ordered in sufficient numbers for the two carriers. Any opinions here?

IMHO, if there are weight increases in LCA Mk2, then the Navy will simply reject the aircraft.

 

[Decklander]

LCA wasn't designed for the carrier from the get-go.

I don't really know why the Navy was suddenly interested in the carrier. As a conversion unit or LIFT, Mk1 is more than enough for the job and that's what it will be used for. I don't really get the point of Mk2 when Mig-29Ks were ordered in sufficient numbers for the two carriers. Any opinions here?

IMHO, if there are weight increases in LCA Mk2, then the Navy will simply reject the aircraft.

Actually, HAL sold the idea to IN and IN true to its colors, went for this domestic industry product. But now it is very clear that N-LCA will be a trainer only with hardly any combat potential. But it will provide a huge tech boost to HAL/India.

 

[p2prada]

The navy has always picked the right stuff for the budget they have to work with. Would be really interesting to know the final decision for any new N-MRCA requirement.

LCA has come down to becoming an industrial winner rather than providing a capability boost to the force. My stand has always been to junk Mk1, induct just 20 for the AF apart from the 6 for the Navy, at least get 4 squadrons of Mk2s for AF and help HAL build up a maintenance and industrial database for an indigenous fighter.

The Navy can induct 8 Mk2s for training purposes. That will give HAL/ADA enough experience before progressing to a "real" carrier aircraft.

Once the 20 Mk1s finish all their development and support operations, they can be moved or converted to Conversion units once the Mk2s are inducted. Pilots being trained on LCAs before moving to FGFA or Rafale will be a big boost to the training curriculum and the quality of the pilots.

A brilliant option would be to participate in the American tender for trainers with the LCA trainer. They have a requirement for 350 aircraft followed by an option to increase it to 1000+. They are currently using F-16s to train pilots on battle space management and navigation before progressing to the F-22 and F-35. Getting that contract would make LCA an astounding success, and would make us an export nation to boot.

 

[p2prada]

USAF releases draft T-X KPPs

The KPPs include a requirement for the prospective aircraft to have an operational availability of no less than 64.7%. It must also be able to sustain 6.5Gs for no less than 15 seconds using no more than 15 degrees nose low attitude at 80% fuel weight between an altitude of 10,000 and 20,000 feet.

Key system attributes (KSA) include the ability to attain a minimum of 7.5G and an onset rate of 3Gs per second. The USAF wants the T-X to be able to attain at least a 12° per second instantaneous turn rate with a sustained turn rate of 9°. It should also be able to conduct angle-of-attack maneuvering at greater than the 20° angle-of-attack. It also needs to have enough fuel for visual range dogfighting and it needs to be able to make dry contacts with an aerial refueling tanker. Other KSAs for the T-X aircraft include having simulated radars, data-links, radar-warning receivers, situational awareness displays and a full glass-cockpit similar to the Lockheed Martin F-22 Raptor and F-35. The T-X must also have the ability to simulate a wide range of air-to-air and air-to-surface weapons including the AIM-120 and Small Diameter Bomb onboard.

The training package must also include networked weapon system trainers (WST), operational flight trainers (OFT), and unit training devices (UTD). The whole system must be able train new students who will eventually fly the F-22.

The simulations must provide visuals equal to 20/20 human vision and must also provide physiological cues to the student. "The WST and OFT shall provide a simulated sense/perception of motion using Combat Edge/G-Suit inflation representative of that which would be experienced in the aircraft at respective maneuvering G-force; as well as a dynamic motion seat," the USAF document reads.

The LCA Mk1 trainer alone should surpass all these requirements and still be cheap enough. Most of the operational stuff like radars can be removed to make the LCA significantly cheaper. Saab is probably thinking of offering Gripen. The Korean T-50 is already taking part.

 

[Kunal Biswas]

Tejas MK2 comes with a better engine, There is should be no issue with Weight when there are few changes in its dimensions only..

Besides Tejas MK1 are better armed / situation awareness than MIG-29 for CAP duties so does it has Anti-ship role and can mount variety of ASM unlike MIG-29..

Tejas MK1 are very effective so does MIG-29..

 

[ersakthivel]

Actually, HAL sold the idea to IN and IN true to its colors, went for this domestic industry product. But now it is very clear that N-LCA will be a trainer only with hardly any combat potential. But it will provide a huge tech boost to HAL/India.

I read somewhere in this forum that you have sent a fighter design of your own to the HAL and received some reply for that. I really appreciate the effort you put in for that. As a designer you must have been very confident of your design to prove it's mettle in the battlefield regardless of the reply from HAL.

In the same way designers of Tejas too must have been very confident of their design. Isn't it? They set out to achieve four very important technological capabilities in the country,

1. Dynamically unstable flight profile fighter that is controlled totally by Flight control software based on Fly by wire tech.

2. Mastering the composite tech,

3. Development of in house open architecture based avionics ,weapon stores system and mission computer along with many important sub systems like OBORG,RWR, indigenous EW suit,

4. Producing a world class radar jet engine .

You should appreciate the fact that they have achieved remarkable progress in some of the above fields and not so remarkable progress in rest as you can easily expect with a complex project of this kind.

In jet engine department they have a working K-9 that produces 10 percent lesser wet thrust even though up to the mark in dry thrust, the radar has been put together with Israeli back end processor from ELTA 2032.

You must measure this magnitude of achievement by comparing it to the fact the country has not produced in numbers even a decent 2nd generation fighter to date.

All this against the strong IAF desire for just another monkey version of MIG-21 like junk.The design team rightly decided that pandering to the IAF's tech blind tunnel vision of a a better Mig-21 is just like a one night affair opposed to the development of LCA which is a lasting relationship cultivated across hundreds of universities and research labs across the country cultivating the ecosystem of aeronautic research development , design and production transforming india into one of the major technological power with critical self reliance in sensitive and closely guarded field of fighter design.

For example no one come forward to help the ADA in worldwide search for consultancy when it comes to fly by wire tech. Even an experienced manufacturer like SAAB crashed the first prototype due to fly by wire issues and went to seek the help of US firms for their grippen.. But the FCS of tejas is praised by each and every one of the test pilots for emergency free 2000 test flights. Now the world grudgingly accepts Indian ability in this critical field.

So I am simply astounded by your statement that LCA is the worst design for any small light weight fighter, Well you are entitled to have such a base opinion of ADA as many other people have of ADA, but do you think Dassault which gave design consultancy for Tejas as also such an incompetent design house to recommend the world's worst fighter design for ADA? Well IMHO that is really stupendous judgement to make.
AFAIK ADA went for low wing loading platform , not low drag platform as many misconceived posters are posting here.

ADA went for most beneficial lift to drag ratio platform which is optimized for carefree unstable handling in the all important transonic flight regime.Many people put a magnifying glass to look at the small ant in the form of higher drag in tejas due to it's large wing. Bt they shut their eyes to the giant elephant called beneficial lift to drag ratio that is critical for high alpha trans sonic maneuvers .

You advised to me to read up on YF-23 in my spare time. You too can have a look at F-16 XL to understand the beneficial lift to drag ratio of the compound or cranked delta wing form that was first tried on it.Despite the higher drag the fighter performed much better than the lesser drag lower sweep version of the normal F-16.it is a universally acknowledged fact that needs no research in spare time .All the details in the following link.

The Revolutionary Evolution of the F-16XL

Ofcourse this design calls for higher wing weight as that of Mirages. But it gives it much lower wing loading in the form of better ITR and better nose pointing ability to have a quicker firing solution for high off boresight WVR missiles combined with HMDS suit.

This design naturally gives the tejas lower STR than the lesser swept wing fighters you mention. But no one can out turn a missile in sustained turn.And the advent of high offboresight WVR missiles has made this parameter not as important as the higher ITR that is the natural out come of the high wing weight low wing loading design of tejas.

The sweep angles for Tejas's wing are the outcome of the mirage like performance asked by IAF,not some arbitrary design assumption by ADA. The wing of tejas is not just a combination of two simple sweeps as you said.

The cranked part near the fuselage is at a different angle to the higher swept wing part near the tip. It is a cranked and compound type arrangement.

The wing has a twist at wing root and mounted in a slightly angular plane on the fuselage opposed to normally horizontal plane arrangement that is normally done.

All this were the result of complex CFD studies done in the computer labs of IIT delhi and validated in extensive wind tunnel testing of the scale model. There are CFD images on the net that detail the huge beneficial lift inducing vortices attached to the upper crank of the delta wing.This is the exact job done by canards in canard delta planforms.


The cranked and compound wing form of tejas achieve the same purpose of the canards without disturbing the aerodynamic efficiency of the wing by ensuring fresh air stream undisturbed by canards at all fligh profiles ,all the times and eliminating the need for extra power hungry and weight causing canards according to ADA. Also it avoids complex issue like force coupling that can be dangerous to the fighter leading to flat spin in some extreme flight profiles and uncontrollable oscillation that caused the crash of the grippen prototype while landing. Carefree canard operation also increases the RCS of the fighter.

I am as an aircraft designer you too would have gone through all the design disciplines. I can understand your contempt for HAL for not accepting your well thought out design. But don't do ADA what the HAL did to your design.

Important consideration in fighter design is the aerodynamic performance of the wing in trans sonic flight profile in which the fighter flies most of the time opposite to fancy topspeeds which will consume all the fuel in minutes .It cannot be based on the sole criteria of the last generation of career based simple delta fighter design's sweep angles.

However according to Navy needs the mk-2 is going to get higher power engines and levcons especially for carrier landing and suitable modifications in FCS using this LEVCONS. LEVCONS also don't disturb the fresh airstream as they fuction as part of the wing oppose to the independent functioning of canards. I think Indian Navy has some faint idea regarding the operational suitability of the fighter on a carrier before sinking in 1000 crores into the project.Once it takes off from carrier it must also fight in the air so we cannot base everything on the ease of carrier landing.

And you can show some belief on the design team initially led by KOTA HARINARAYANA to deliver a better than junk fighter to Indian Navy.The following link will give you some idea regarding the persona of KOTA HRINARAYANA

http://tejas.gov.in/featured_articles/dr_kota_harinarayana/page01.html

 

[ersakthivel]

LCA wasn't designed for the carrier from the get-go.

I don't really know why the Navy was suddenly interested in the carrier. As a conversion unit or LIFT, Mk1 is more than enough for the job and that's what it will be used for. I don't really get the point of Mk2 when Mig-29Ks were ordered in sufficient numbers for the two carriers. Any opinions here?

IMHO, if there are weight increases in LCA Mk2, then the Navy will simply reject the aircraft.

Navy knows much better than that.They are no fools to sink 1000 crores voluntarily without being asked by ADA and HAL.navy thinks levcons along with much powerful engine will give mk-2 enough performance boost for carrier ops considering the dated versions of MIG-29s and Harriers they are operating as carrier fighters that are at the end of the product lifecycle with no scope for further upgradation opposed to brand new tejas that is just starting it's development lifecycle.

If it shows Mirage like performance even with half of mirages combat load the navy will be well served by tejas mk-2.No one is lining up to sell navy a brand new tailor made fighter they want with any useful capacity over mk-2.Even if they do ,the development cost they will ask alone will be more than the cost of the few squadrons of fighters they need.

 

[ersakthivel]

Never come across any official data that claims Top Speed at Mach 2 for Tejas Mk2 ....since it has fixed intake it will be around ~ M 1.6-1.8

If its Top Speed at sea level then yes the data is correct.

There are auxillary air intakes added to the LSP-7 and 8 which are the actual production version to increase the airflow when needed after extensive design studies.
The LCA attained mach 1.6 before these aux intakes.
We need to see how much it will help in attaining much better top speed.