LCA News and Discussions

[Katare]

This makes it half the expected cost of MRCA in development budget of LCA only and if 200 LCA (IAF/IN) are built it'll cost another Rs30k corer. Not a tiny budget,

Whatever the cost may be, LCA program woud keep atleast 80% of the money in India creating local jobs. If $15b purchases save 27000 jobs in USA, how many jobs will be crated in India for the same amount?

What is better option? 250 LCAs along with a full production line for emergency situation or 126 MMRCAs?

Rama, What is the point of stating obvious? You know the answers! You should be happy that an Indian domestic program could turn out to be much bigger than the largest procurement we are attempting right now.

[Jayram]

Apropos nothing - but here's a little titbit. I was searching for info on "clean" and "dirty" configurations and I found a pdf containing technical info - most of which I could not understand - but what I did see was the finding that slinging a weight under the wing of a Tornado actually increased the fatigue life of the wing. The explanation was that the wing was much more stressed (bending up a lot more?) when it had no stores so carrying some weight was beneficial. Maybe that is why the Tejas is always seen carrying a mijjile under each wing?

This may be due to increase in flutter in absence of weight and any damping due to a weight would actually cause the flutter effect to decrease and thus increase fatigue life.

[geeth]

Apropos nothing - but here's a little titbit. I was searching for info on "clean" and "dirty" configurations and I found a pdf containing technical info - most of which I could not understand - but what I did see was the finding that slinging a weight under the wing of a Tornado actually increased the fatigue life of the wing. The explanation was that the wing was much more stressed (bending up a lot more?) when it had no stores so carrying some weight was beneficial. Maybe that is why the Tejas is always seen carrying a mijjile under each wing?

The reason could be due to following conditions.

Take for eg., one sq.Metre area at the tip of one particular wing. If the lift produced by that wing at that particular one sq.Metre area is (say) 300 kg (upwards) and acting through the centre of area. Now you hang a missile of 150 kg weight at the centre of this one sq.Metre area. Assume the distance to wing root as 3 Metres.

The effective shear force is (300-150) = 150 kg upwards at the point of sling
Bending moment = 150x3 = 450 kg-metre

The respective figures for a clean configuration would be 300 kg up and 300x3 = 900 kg-metre.

The same effect is there when you fill the wings with fuel and sling engines under the wing. HOWEVER, the designers are aware of these advantages and design the wings accordingly, to save weight.

[Indranil]

^^^ I don't think that would be the right physics for 2 reasons. Please correct me where I am wrong.

1. The body of the plane is not tethered. so if the wing created more lift, it will lift the body higher, rather than generating a greater strain. Look at the physics on the force diagram of the fuselage. There is lift by the wing and weight. It's net upward acceleration is (L-Mg)/M, where M is the mass of the fuselage. Also at altitude the lift almost equals the weight of the plane.

2. With all due respect, the above explanation might hold good for a level flight. What about turns? At 4Gs the equation would become the opposite. The lift generated will remain the same. But the centripetal force of the missile will now be pulling much harder!

I can only speculate now (Shivji I will be very grateful if you point me to a pdf).

I think it is got to do more with the arc that the wing makes when in flight. By slinging the a weight at the end, one makes the wing more level. This decreases the dihedral and eases the strain at the wing fairings. Also it will greatly dampen the amplitude of flutter. Imagine a metal strip tethered at one end. You can easy make this sheet buzz. However, when you put it between two tethers. it is harder (it will still flutter, but the harmonics and amplitude will be different). For a wing which has depth this flutter has an fatigue effect at every join along the wing. Obviously a lesser amplitude has huge benefits.

P.S.
Just thinking aloud here. I was thinking whether the benefits are wing specific. I see this tactic being employed on Delta wings almost often. However the same is not true for Su-30, Mig-29, F-15, F-14, F-15. However, the Panavia Tornado has a high aspect ratio wing! So I am not sure.

[aditya.agd]

Replace as many mig-21s as possible with LCA Mk1. I would assume that LCA is little better than MIg21 on atlleast 'safety of pilot' point of view.

[Indranil]

I don't think that the LCA has completed the weapons testing or high AoA tests. I think the IAF would need atleast that much before it starts a mass exodus of the Mig-21/Mig-27.

[shiv]

I can only speculate now (Shivji I will be very grateful if you point me to a pdf).

http://ftp.rta.nato.int/public//PubFull ... 015-09.pdf

[geeth]

^^^ I don't think that would be the right physics for 2 reasons. Please correct me where I am wrong.

I was responding to a specific case quoted by Shiv in simple layman's terms. Please refer Page 14 of PDF link provided by Shiv.

Calculating the fatigue load is a complicated process and involves a clear understanding of the full flight envelop of the aircraft and the materials used to make it.

'Buffeting' caused by the flow over aircraft is still more complicated, because the structure may behave differently at subsonic, transonic and supersonic regime of the flight, and is not something which can be easily explained away. Any elementary books on flight dynamics will give an idea about the loads acting on aircraft.

[Indranil]

Geeth sahab,

I don't mean to challenge you. But I feel the explanation was not right. Think about the wing join. If you want to lift the fuselage at certain acceleration you have to apply a force of MA in the direction of intended acceleration. This force will be provided by the strain at the wing join. This would not change whether we add any weights underneath the wing! For example if you are flying level, the two wing joins should provide a total upward force of Mg where M is the mass of the fuselage. It doesn't change if the wing has pylons or not.

I read the paper and Shiv sir said and I would recommend it to anybody who is interested in understanding structural aspects of a plane. There is lot of generic information.

I feel my speculation was not very far off. Actually the paper (as you rightly pointed out on Page 14) summarizes as follows:

As indicated, for the Tornado the wing root bending moment is 11% less carrying outboard stores than for the clean wing without stores.

As you can see, this is not about the strain passed to the wing to the fuselage because of lift. It is the bending which matters. Please consider the case where they consider the difference between putting the missile on the outboard pylon rather than the inboard pylon. According to your explanation, there should be no difference. But the researches find a difference of 7%.

I think the import of the paper as something completely different. The paper discusses the deviation from design life because of operations. For example if the plane was designed for a certain for a certain front fuselage weight, and we suddenly add weight in upgrades, the life would change. If the wings were designed to carry atleast wingtip missiles, it is not good if the plane flies "clean" or vice-versa. The researchers try to bring out how operational life could greatly vary from design life if the "intended" role is not followed.

[Austin]

AW&ST LCA Limits

[Gaur]

^^
Austin Sahab,
Why not post the link instead of a screengrab? That would be much more convenient for all of us.

[shukla]

CTTC, Bhubaneswar to produce certain Control System components for LCA
Machinist

The Central Tool Room & Training Centre (CTTC), Bhubaneswar has been identified by Aeronautical Development Agency (ADA) as the production centre for the bulk production of Fuel and Environmental Control System components for Light Combat Aircraft (LCA). The Center for Military Airworthiness & Certification (CEMILAC) selected CTTC for successful absorption of manufacturing technology of these components, after assessing for bulk production capability. The components have been validated through special tests on the components manufactured by CTTC.

Shri PS Subramaniam, PGD (CA), Director, ADA and Dr K Tamilmani, CE, CEMILAC, jointly issued the certificate to Shri Sibasis Maiti, General Manager, CTTC, to recognise as the production centre for manufacturing of Fuel and Environmental Control System components of LCA in the presence of Shri Satyananda Mishra, Information Commissioner, Govt of India. The design and development of the Fuel and Environmental Control System components was done by Aeronautical Development Agency (ADA) in association with Government Tool Room and Training Centre (GTTC), Bangalore.

[Austin]

^^
Austin Sahab,
Why not post the link instead of a screengrab? That would be much more convenient for all of us.

Hahaha , Well you wish and you get it

http://www.zinio.com/reader.jsp?issue=416146354&e=true

[geeth]

I don't mean to challenge you. But I feel the explanation was not right. Think about the wing join. If you want to lift the fuselage at certain acceleration you have to apply a force of MA in the direction of intended acceleration. This force will be provided by the strain at the wing join. This would not change whether we add any weights underneath the wing! For example if you are flying level, the two wing joins should provide a total upward force of Mg where M is the mass of the fuselage. It doesn't change if the wing has pylons or not.

For simple calculations, you can take the half wing as a cantilever beam (except for parasole wings) and put the lift force as distributed load acting upwards and the weight of missile as concentrated load acting down. If you look at the aircraft from the front, the lift force acting up would exert a bending moment in the clockwise direction at the left wing root and a counter-clockwise bending moment will be exerted by the under slung missile load, thereby nullifying part of the bending moment exerted by lift force. In actual design, lot many more parameters like torsion loads, dynamic loads etc will also come into picture. This is most elementary calculations you can see in books like Timoshenko & Young.

As you can see, this is not about the strain passed to the wing to the fuselage because of lift. It is the bending which matters. Please consider the case where they consider the difference between putting the missile on the outboard pylon rather than the inboard pylon. According to your explanation, there should be no difference. But the researches find a difference of 7%.

I haven't said anything differently. If you sling the missile at 2 Metres (in-board) from wing root, the nullifying bending moment will be only 300 Kg-M (150x2) instead of 450 kg-M when you sling it at 3 Metres (outboard). Therefore, slinging the missile outboard reduces the overall stress at wing root for this particular case.

[shiv]

Has this been posted before?
http://www.youtube.com/watch?v=bT_R1FRo_Rw

[Rahul M]

yes saarji, many times. came out around AI09. but I think it should go in the opening post too.

[neerajb]

Has this been posted before?
http://www.youtube.com/watch?v=bT_R1FRo_Rw

Thanks for sharing Shiv. At 05:15 the video says External Stores - 4000 Kg, Empty weight - 6500 Kg and Take-Off clean - 9500 Kg. Now if we assume that the increase in new take off clean to 9800 Kg from 9500 Kg is purely because of increase in empty weight ( rest of the stuff remaining the same), The empty weight comes to around 6800 Kg.

Cheers....

[Indranil]

Geeth Sahab,

My humblest apologies. You and I are peaking of the same thing. I didn't realize you were also speaking of the bending, when you were clearly doing so.

I know that it is way more complicated than this but it is interesting that while writing my explanation I was also thinking of a cantilever bridge "tethered" at two ends.

[Indranil]

Can we start a good discussion on inlet design of the LCA. I implore the hugely knowledgeable guys out there who have stopped posting on BR and I am sure who are still lurking around to please please bliss this corner again.

I see the JF-17 in the air and it is doing the high AoA with considerable ease. Its inlet (just the entry looks more constricted than the LCA. It has no bevel either. If anything it is beveled back wards. Then why is the LCA inlet thought to be choking at high AoA. Something to do with the ducts inside?

It would be nice if we stick to exact details and not speculate. We had a good discussion about the wings. Let's decipher the inlets this time.

I can spot a few differences though
1. The inlet seems taller than that of the LCA.
2. From the front view it looks like two lobes one at the top and another at the bottom. Since the inlet follows the body contours, the upper lobe is not directly above the lower lobe. Does this have a role to play?

[Kartik]

In relation to a previous discussion on the Ultimate and Limit loads to which the LCA would've been designed- here is further proof that 150% of the limit load is generally all that any aircraft will be designed to unless special reasons exist for going above or below that figure.

article link

DATE:22/11/10
SOURCE:Flight International
Fatigue cracks raise questions about key decision in F-35 redesign
By Stephen Trimble

Questions raised over 2004 weight-saving decision to switch key F-35 structures from titanium to new aluminium alloy

Lockheed Martin has discovered fatigue cracks on an aluminium bulkhead inside a ground test aircraft for the short take-off and landing F-35B variant after 1,500h of durability testing.

Among the possible causes is a test malfunction, a manufacturing error or a design flaw, Lockheed says. As the durability test airframe, BH-1 was being subjected to forces simulating aerodynamic loads the airframe would experience over two lifetimes, or 16,000h. The fatigue cracks were revealed by a special inspection within the first one-tenth period of the testing cycle.

Until now, Lockheed's ground tests to verify the strength and safety of the F-35 structure had progressed smoothly. In June, for example, the CTOL AG-1 airframe completed static testing that proved the airframe can survive 13.5g loads, or 150% higher than Lockheed's required limit of 9g.

And some things to keep in mind when we talk about weight reduction..it has to be done carefully not willy nilly.

As the investigation continues, questions will be raised about a key decision in the 2004 redesign. As part of a broader strategy to reduce airframe weight, Lockheed decided to switch from titanium to a new Alcoa alloy - 7085 - for the load-bearing bulkheads.

For Alcoa, Lockheed's decision was an industrial coup. Designed for a wing spar in the Airbus A380, the 7085 alloy had received its first military customer. Three years later, in May 2007, an Alcoa executive touted this success in a briefing to financial analysts.

"The aircraft [F-35] was overweight. They needed significant weight reductions," Alcoa Power and Propulsion president Ray Mitchell said. "They were trying to do it with a two-piece solution. We were able to, with our proprietary alloys, offer them a single piece solution that would be lighter weight and greater strength. So they redesigned this entire part of the airplane and didn't lose time."

[Prem Kumar]

what an absolute moron this rajat pandit is, or should I say paid hack. so 560 crores in 1983 has same value as 17000 crores in 2010 and with 2 new derivative projects added ?

how about inflation rate of INR since that time or the fact that the rupee went at 10 to a $ at the time.
the smear campaign against LCA and in favour of gripen continues using the unscrupulous lowlifes in the media.

When I first joined BRF, I used to think DDM stood for "Desh Drohi Media", given the number of hatchet jobs they put out. Maybe that wasnt too far off the mark.

[SaiK]

NLCA: the LEVCONs will also increase controllability at high angles of attack AoA.

high-energy air-flow along the tail fin to enhance high-AoA stability.

The wing-shielded, side-mounted bifurcated, fixed-geometry Y-duct air intakes have an optimised diverter configuration to ensure buzz-free air supply to the engine at acceptable distortion levels, even at high AoA.
http://www.museumstuff.com/learn/topics ... ub::Design

more :
http://www.csirwebistad.org/aesi/pdf/ft ... _TEJAS.pdf

check other links from the museum stuffs! that I can't get to - timeout error.408

[Kartik]

Can we start a good discussion on inlet design of the LCA. I implore the hugely knowledgeable guys out there who have stopped posting on BR and I am sure who are still lurking around to please please bliss this corner again.

I see the JF-17 in the air and it is doing the high AoA with considerable ease. Its inlet (just the entry looks more constricted than the LCA. It has no bevel either. If anything it is beveled back wards. Then why is the LCA inlet thought to be choking at high AoA. Something to do with the ducts inside?

It would be nice if we stick to exact details and not speculate. We had a good discussion about the wings. Let's decipher the inlets this time.

I can spot a few differences though
1. The inlet seems taller than that of the LCA.
2. From the front view it looks like two lobes one at the top and another at the bottom. Since the inlet follows the body contours, the upper lobe is not directly above the lower lobe. Does this have a role to play?

The FC-1 originally did have an intake splitter plate. They ran into some problems during the first series of flight testing and then went into a serious design modification phase.

They basically used their academic and industrial espionage activities (LM collaborated with Universities in the US for work on the DSI intakes) to get information on the DSI (Diverterless splitter intake) intake design and applied it on the FC-1. Before that, no Chinese, heck no non-US aircraft had been designed with the DSI intake and the only for-production aircraft that was supposed to feature it was the F-35. The F-16 inlet was modified and tested with the DSI intake with no noticeable loss of power throughout the flight envelope and instead around 2% gain in some profiles. This was LM's proprietary piece of work and the Chinese implemented it on an aircraft they intended to put into production- no test examples, no experimenting with some other testbed, etc. Coincidence ? I beleive not.

Anyway, the espionage aspect aside, they also included the Super Hornet style LERX and IMO, that is the reason we see those vortices flowing off so well on the JF-17 that performed in the very humid conditions at Zhuhai. And that is crucial for the high-alpha maneuvers- the ability of the wing to continue to generate lift without stalling suddenly.

Even before that, keep in mind that the FC-1 essentially uses EXACTLY the same planform as the F-16, a wing shape that was known to be a good performer. You can test it yourself- take an F-16 in plan view and a FC-1 and hide their forward fuselage and LERX and you can barely tell the difference between the two. There have been reports indicating that the PAF faked a crash report and in fact transferred an F-16 airframe to the Chinese to help them in reverse engineering it. There is no doubt that this would've been useful in gaining an insight into what to look for in the various structures, how bulkheads, ribs, stringers, spars, longerons, panels, fittings, etc. could be designed (not that they didn't know earlier, but taking apart a superb airframe like the F-16 would be very different from taking apart a MiG-21, from which the original FC-1 design flowed and which was the Chinese technological level back then). At the very least, it gives you a starting point of a fighter that you know is a very sound design. If you replicate it even to 70%-80% effectivity, you'll not be doing so bad.

The reason I'm telling this is that the first Grumman originated designs for the FC-1 (Super 7 back then) showed a distinct lineage with the MiG-21. I have a picture at home from an old Flight International that showed the Grumman Super 7 design back then compared to the J-7. It had MiG-21 style delta wings and a very MiG-21ish fuselage. The only difference was the radome was sharp instead of being ogival and intakes were side mounted. The FC-1's fuselage shape is still very similar to that of the MiG-21 (just as the LCA's fuselage takes a lot from the Mirage-2000). But at some point in the mid-1990s when Pakistan joined the program, they would've had a chance to inspect and study the F-16 and gain an insight into how well its wing shape worked compared to the J-7 or J-7Gs. an F-16 transfer must have happened or else Chinese were given very close inspection of PAF F-16s to use that as the baseline for their joint FC-1 project.

Anyway, back to the DSI- it is not a must-have since even the other designs either in work in the early to late 2000s (like the T-50 Golden Eagle, PAK-FA, AMCA, Japan's fifth gen fighter mockup, South Korea's planned KFX-2, etc.) don't feature this type of inlet.

The FC-1's maneuverability seems decent enough for it to be a valid threat to us. But its roll response is distinctly sluggish compared even to the F-16. Not to mention the Mirage-2000, Gripen and even the LCA (which from videos seems to have nearly 250+ deg/sec roll rates) which benefit from lower wing loading. That means its instantaneous turn rates will definitely be slower than the LCA..the LCA's sustained turn rates may be lower than the FC-1's due to its large delta wing. But those things are common between two other types also- the Mirage-2000 and the F-16. They simply lead to different tactics during missions with the Mirage hoping for a slash and run type attack using its higher instantaneous turn rate advantage initially, as versus the turning knife fight that the F-16 hopes to get into due to its ability to turn sustained better without losing so much energy.

the FC-1 being a relatively simpler FBW fighter than the LCA, its testing would've been easier and its envelope must have been fully explored by now, which allows for high Alpha flights and higher G maneuvers. Nevertheless, compare it to a Gripen and it doesn't stack up at all not even from an airshow performance aspect. So the JF-17 is not suddenly the gold standard to be compared to, even though kudos to the Chinese for being able to develop 2 different aircraft simultaneously. It’s a sign of how big a threat they will be in the coming decades as an aerospace power. The Pakis just too k the ride along and now want to hog the glory despite having not a single part of the FC-1 designed by themselves. They only did one thing- keep the design specs achievable and give the program full-hearted support, unlike the IAF. It does wonders to the morale of the designers, it really does. Something India will NEVER be able to do for sure.

And another thing- keep in mind also that the FC-1's basic design weight was in response to a 8G load factor- i.e it can withstand 8 Gs limit loads and not 9 Gs like most other contemporary fighters. Empty weight wise, it weighs as much as an LCA although it was designed for 1 G less load factor. The only one I can think of is the MiG-29K which is limited to 8Gs or so due to the wing being the folding type. When the time comes for weight reduction, if the IAF accepts a 8 G limit load designed fighter, the LCA will be easily able to shave off 300-400 kgs off its primary structures.

Sorry my post seems to have gone all over.

[Karan M]

^^

No, its an excellent post, like most of the ones you make.

I believe even STR will be pretty ok for the LCA and upto original ASR's or even better once the MK2 comes out. Even in the present version, with an ELBIT DASH helmet, and Python-V missiles, the LCA will be a very capable fighter in WVR.

The Python 5 capabilities are discussed here:
http://www.youtube.com/watch?v=nWG2PkwKiaQ

Basically, whats happening here is the incoming fighters use HMD to cue their Python5's and escape the entire turning fight scenario, while the opponents try for a conventional approach, get into the merge scenario, and get hammered.

The reason I am bringing this up as it complements your post. Normally, one crucial aspect that is often missed though is the avionics aspect. I was reading up on these two aircraft, and it amazes me as to how the PAF has accepted a few of these type, going so far as to start up a squadron, tom tom its capabilities, when it is actually in several respects lagging the Tejas MK1. This either points to the PAF being supremely pragmatic (take whatever is possible) and of course, their own pitiful situation, tough talk apart, with aircraft that are mostly obsolete bar a handful of F-16s and upgraded Mirage 3/5s. And even those Mirages will need to be replaced.

The fact that they tried so much for a French solution, only to go Chinese when there was no other option, and the French were providing everything, from glass cockpit, to controls, to radar, mission avionics, really does not speak well for the overall sophistication of Chinese industry. In contrast, if we look closer home, IAF, a tough as they come customer, is actually replacing import items with local ones.

The JF-17's combat capabilities, whether the Paks., admit it or not, has taken a beating, with weapons and avionics fits going from worldclass items sourced from France to "acceptable" or "whatever exists" from China. Now the Chinese are no walkovers, but when your first export customer, ends up looking abroad for a majority of combat critical avionics, it does say something. From a probable good helmet sight, to a good radar (RDY3), other electronic gizmos and the very sophisticated Mica missile combination, they are going to simpler systems across the board. The SD-10 missile, per what I have read so far, basically has a more powerful motor than the original R-77 missile, but its electronics are an unknown quantity, and I do have doubt's whether it is all it is cracked out to be. Now a larger plane, J-10 can cram larger systems (radar with a larger dish) but light fighters actually need very weight and performance optimized systems where every bit of technology helps.

[andy B]

^^^ Karthik not at all...its a great informative post please keep em coming.

[SaiK]

Awesome post Kartik.

[Singha]

did the french deal not happen due to french objections (unlikely) or money issues?

[Kartik]

Thanks Karan, andy and Saik.

[Indranil]

I think I conveyed myself wrong here. I didn't to establish the JF-17 as the new standard. I know better . The JF-17 obviously looks like a Mig-21/F-16/F-18. Whatever be the source, they have got a good plane (aerodynamics wise).

I was only kick starting a discussion on the inlet design. I am trying to understand why LCA intakes would work at high AoA/ or why not! JF-17 is just one example. Please feel free to add other examples and details on how it is related to the LCA intake etc etc.

Sai sahab, that CSIR link is failing on me too .

Can we get a diagram of LCA intake to start with?

[geeth]

Though not specific to LCA, this paper gives some ideas about design of air intakes for different types of aircrafts.

http://www.scribd.com/doc/24418180/Stud ... aft-report

[aditya.agd]

Thanks Karthik for that detailed analysis. That helped me to understand the adversaries better.

However, I have one question. How does MK1 compare to JF-17 and other new Chinese planes?

[SaiK]

Can we get a diagram of LCA intake to start with?

goto page 1 on this thread and check out shiv's post.


BTW, your AoA quests seems to be getting into AoI (inlet).

[rad]

I join Kartik`s opinion where he says that the wing design of the jf-17 was lifted and put on the jf-17. and added lerx of the f-18 and the intakes of the f-35 The wing planform seems too identical to be an original design.
Moreover when the f-16 is a classic design success ,why waste time in reinventing the wheel ? when there is a
ready made f-16 waiting to be copied. We should understand that at one point of time pakistan was treated as a pariah in the international world and nobody would deal with it especially during the time of the kargil war . During These low times when it was under sanctions . they had all the time in the world to let the chinese engineers have a thorough detailed look , they would have taken measurement to the micron level and designed a mainbody around the wing which is simpler . We should also understand that the chinese are very very good in copying technology , we have to give them credit for that ,sadly we dont have that capability or the guts to do so .They copied the su-30 and the russians dint have the guts to take action ,In fact i hear that they are willing to sell them the su-35 as well !!. They copied every successful russian weapon including the smerch rocket and its launcher and sold it to pakistan , they claim it is as good or better. They are also copying the s-300 missile system and and it wouldnt be long before they sell it it to the pakistanis, They handed over complete tomahawk cruise missiles to china when some of them fell in pakistan territory during the afghan war.
10 years later the chinese made them the babur missile and handed it over to them immensely gaining from the technology . Industrial espionage is a forte with the chinese and every chinese student that works in hitech labs in universities around the world will come home and do the same thing.It seems the west has sold its soul to the chinese for money , they will regret it .
The jf-17 has a FBW channel in pitch only which is good enough for optimum turning performance, all they have to do is to roll and pull hard and let the computers do the work. They are also working on the full fly by wire version ie in all 3 axis . It wont be long before a mk2 version with all this starts flying . I think it is prudent to go that way by building sophistication step by step in to the airframe . Seeing the video of the f-17 i would say that it has a good turning performance and there is a video where it is being compared to a f-16 in a turn etc . We should also understand that the Israelis sold them all the tech of the Lavi fighter in including the avionics thats why they have similar lcd displays on the jf-17. if one would look into old popular science magazine where they had a report on the Lavi it would be clear .
They have some unique weapons like the ws-6 glide bomb which is inertial and gps guided giving them a stand off cheap weapon, we dont seem to have an equal to that . We dont seem to have a ready medium range missile integrated either. I do believe the LCA would be better in roll and instant turn rate and with a better engine improve the sustained turn. I really dont know if classic dogfights will take place all the time like in the 71 war given that both sides have AWACS to guide them for a missile shot . It would be wise to treat the jf-17 equal in all respects in avionics , We could have an edge is in the EW scenario with the help of the Israelis . The jf-17 seems to have every system incorporated or under design what we propose to do on our LCA.

rad

[Vivek K]

So what has stopped us from adding exisiting successful solutions to the LCA?

[Indranil]

Sai sahab,

You got it right ... I am trying to understand the design of the LCA intake and have a broad understanding of why it should/should not work at high AoA.

[Kartik]

I think I conveyed myself wrong here. I didn't to establish the JF-17 as the new standard. I know better . The JF-17 obviously looks like a Mig-21/F-16/F-18. Whatever be the source, they have got a good plane (aerodynamics wise).

I was only kick starting a discussion on the inlet design. I am trying to understand why LCA intakes would work at high AoA/ or why not! JF-17 is just one example. Please feel free to add other examples and details on how it is related to the LCA intake etc etc.

Sai sahab, that CSIR link is failing on me too .

Can we get a diagram of LCA intake to start with?

I'm afraid that based on open source information you cannot just sustain any detailed conversation on the (possible) issues with the LCA's air intakes, such as whether or not there are issues with compressor surge at high alpha or inadequate airflow or not and why it is happening. Unless you or someone else has any in-depth knowledge of the LCA's inlet and air-passage design and access to data (which anyway cannot be discussed on open forums), you would just be guessing.

I mean how would someone not associated with the program and the intake design know what amount of CFD analysis went into that design and what issues (if any) were seen? Or how does someone not associated with the test program know what is holding them back from high alpha tests as of now (aside from Ajai Shukla's claim that it has a chance of flame out at high alpha, there is no information on this). It will be quite like the blind men touching various parts of the elephant and trying to ascertain what it looks like based on that. It might end up misleading more than enlightening.

I'm afraid you cannot get any real details on this unless someone has an in-depth interview and conversation with those associated with the LCA program.

I hope Gp Cpt Hari Nair could convince one of the test pilots (even HAL) to talk about the status of the LCA's flight tests, its progress and possible issues. Could our moderators ask him by sending him a message? These are the times when I really really wish that BRF had its own publication (even if only internal) where BRF members would get press accredition and be able to seek out ADA officials and have their interviews. The content could be much more specific and balanced than what our current crop of defence journos like Shiv Aroor, Ajai Shukla, etc produce..Ananth Krishnan unfortunately doesn't look to go into the technical details in his interviews.

[Indranil]

Ya that is right .

I would love press cards for one more thing. I love photography and have invested quite heavily on cameras and lenses ... If only I could get closer to those planes, I could get good pics for BR. Anyways, seems like that won't happen either .

That aside, Shiv sir it would be interesting to know what your birdie who seems to be knowledgeable about the Kaveri thinks about LCA's intakes.

Chacko can you dig deeper about this with somebody?

Has there been any official release that the LCA intakes would be modified on Mark II for want of higher AoA. I read somewhere that they will have to modify it for the new engines.

[shiv]

Comparison of the LCA, J-10 and JF-17 in airshows
http://www.youtube.com/watch?v=gX4W-goLSIo

[shiv]

Indranil I will certainly ask my birdie when I meet him next but I am not at all sure how BRF reached the conclusion that changes in the intake. if any, would be needed for the specific purpose of improving high AoA performance. Is that a musharraf-retrieved assumption?

[suryag]

LCA Tejas technology developemt - 2/2

At 7:53 in this video, what do the various colours flying of the wing signify ?