LCA Tejas: News and Discussions

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LCA Tejas: News and Discussions

Postby Indranil » 11 Feb 2015 02:51

Link to last incarnation of this thread

=============================================================
Background articles on HAL Tejas (LCA)

_____________________________________________
Excellent overview of Tejas, from the developer itself.
http://www.tejas.gov.in/
_____________________________________________


1. Wikipedia entry on Tejas

2. Remembrance of Aeronautical Matters Past (Brief history of India's Aerospace Industry)

3. All the articles at BR page on LCA.

4. ACIG Exclusives on Tejas

5. Good background on project, a bit dated.

6. Harry's Radiance of the Tejas article

7. Approach to High Angle of Attack Testing of Light Combat Aircraft [LCA] Tejas

8. Aircraft Performance Improvements-A Practical Approach

9. ADA overview on LCA, including interviews of test pilots, a peak inside the R&D labs and rare footage.



10. Air Commodore KA Muthana, Indian Air Force [IAF], Technology Director [Flight Test], speaking at the Aero India 2013 Airshow Seminar. Critical Lessons Learnt From The Design And Development Of India's Light Combat Aircraft [LCA] Tejas.



11. Capt. Maolankar India's Naval Light Combat Aircraft [LCA-Navy] - unique features & flight testing.




Newbies beware ! If you make ignorant remarks, you could be grilled by gurus to test your LCA knowledge from these pages !
And, if you come out deficient..............(you would do better not to find out !)
:twisted:

Please stay on topic.

That means :
a> No comparison with aircraft A,B or C.
b> No half-baked suggestions to improve LCA like "add a laser gun"/"merge DRDO with ISRO " etc etc.
c> NO whining.

======================================================

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Re: LCA Tejas: News and Discussions

Postby Prem » 11 Feb 2015 03:32

Please watch it manoeuvring At 8*43,

Last edited by Prem on 11 Feb 2015 03:41, edited 1 time in total.

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Re: LCA Tejas: News and Discussions

Postby srai » 11 Feb 2015 03:39

This deserves to be posted with new thread starter for the LCA.

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Re: LCA Tejas: News and Discussions

Postby srai » 11 Feb 2015 05:12

Good reference at the beginning on new LCA thread (from Aero India 2013):

Kartik wrote:Attended my first Aero India this Saturday. I won’t describe the difficulties in getting into the show, but once I did, it was quite alright. The highlight for me was the conversations I had with Cmde Jaydeep Maolankar, Test Pilot of the Tejas program and Cmdr Sukesh Nagaraj (Deputy Project Director, NLCA). I was lucky to spot Mao sir alone and walked up to him, introduced myself and spoke of my association with BRF and then we had a conversation on the Tejas program for half an hour..he was incredibly frank, friendly, didn’t hold back any facts and only left when he got a call from someone..here are the salient points of our conversation, some of which we already know but am listing it anyway.

- Tejas LSP6 is the platform on which the spin chute will be integrated but it’s not here as yet. Will get done before FOC.
- Tejas Mk1 has achieved the IOC AoA limit of 22 deg and they will go a couple of degrees further in tests, when the spin chutes are integrated on LSP6. This is to ensure that they know that the airplane is safe even at higher alpha although the FBW will restrict it to the AoA limit for FOC for service pilots (which is higher than 22 deg, but he didn’t say how much)
- Mao Sir scoffed at the suggestion that the engine was choking at higher alpha. He said there is no such thing, but rather because it was designed initially for the Kaveri’s airflow and had to redesign it for the F-404. They have already tried various intakes on the LCA, with/without spring mounted doors on the intakes.
- Tejas MK2 will get an approx 10mm increase in diameter for the increased air flow requirement of the F-414 (Cmdr Sukesh Nagaraj confirmed this as well). Too small a difference to be visible to the naked eye for us jingos. The spring mounted doors may also be bigger if needed
- When asked about the STR and ITR rates of the Tejas, he simply smiled and said “it’s enough, let me put it that way”. When I queried him further, asking about the ASR that the IAF had set based on the Mirage-2000 and MiG-29’s STR and ITR, his smile vanished and he got serious. He said that when people look at 10 different brochures and come up with requirements, without looking at whether meeting all those requirements is even possible for ANY one fighter, they set themselves and the program up for failure. He was very frank about this, stating that even those brochure specs were just that- brochure specs that even those famed fighters sometimes don’t meet. But they were taken as benchmarks anyway and then, without even bothering to look at the technological base in India, the ASR was prepared.
- He was full of praise for the handling of the Tejas. It’s a true delight to fly and both he and Grp Cpt Suneet Krishna have tremendous confidence in the aircraft itself. He said that they both push the aircraft to its current limits without any worry since the FCS is very good. He did mention that they didn’t push the Tejas Mk1 to its limits at the airshow but just wanted to display that it is maneuverable enough.
- When I asked him whether the Navy fully backs the NLCA program, he laughed and said “I’m here, aren’t I?”. So all in all, it appears that the IN is backing the program fully
- NP1 hasn’t flown more than 4 flights because they’re re-designing some of the structures on board. This is the additional strengthening required for handling the thumping that is a carrier landing. The landing gear is being re-designed since its overweight and NP2 is going to fly soon.
- I brought up the point he made at AI-2011 about how the Tejas should’ve started as a carrier variant and then gone on to the IAF variant. He seemed genuinely happy that someone had remembered that point of his and described the main issue with the NLCA NP1. The issue as he described it was that the LCA didn’t have a central keel to pass the structural loads to, something he said that the AMCA won’t face since it’s a twin engine fighter. This meant that they had to put new attachment points which aren’t the ideal solution and result in the bulky appearance of the current landing gear.
- I was going to ask him about the AMCA naval variant and he said that currently there is no plan for it.

At this point he had to leave and I was disappointed since I hadn’t gotten to discussing anything about the Elta 2032/MMR, Litening LDP and the weapons on the Mk1 such as the Derby/Python V/R-77/Astra and Sudarshan..


Kartik wrote:Next, I went to the ADA stall and just asked aloud if anyone could talk to me about the Mk2. A gentleman in a suit stepped up and said “Yes, what do you want to know about it? Which one, the IAF Mk2 or the Navy Mk2?” and I said “IAF Mk2” and he laughed and said “oh, you disappointed me, I was hoping you’d say Navy Mk2”..:D Turned out, it was Cmdr Sukesh Nagaraj, Deputy Project Director of the N-LCA program..I was blown away by this gentleman. Here was one of the top decision makers of the Tejas program and he was warm, friendly, forthcoming and genuinely interested in talking about the program without even asking me what my background was (till much later in my conversation). He was an engineer on the Sea Harrier, having served on the Viraat. Said he was rookie when Cmde Maolankar commanded the squadron. The salient points of the conversation with him were:

- The Tejas Mk2 is being lengthened by 0.5m only and not 1m as that big gasbag Prasun Sengupta was fibbing about. We really ought to never take him seriously at all. The reason cited were CG change primarily.
- F-414 was primarily an IN requirement. It turns out that the IAF was fine with the F-404IN20 engine on the Mk1. They jumped on the IN’s requirement for a higher thrust engine and requested the IAF Mk2 variant.
- The fuselage on the Mk2 will be slightly wider as well due to the larger diameter of the F-414 engine. This will be used to put onboard additional fuel
- The widening of the fuselage will push out the wings a bit, thus increasing wing span. Otherwise no increase in wing span as such. It doesn’t need it, since the wing area is massive already
- Additional fuel will be required primarily to offset the additional weight (he said approx. 200 kg additional) and higher SFC of the F-414 engine. So, it appears that the Tejas Mk2’s range may not go up significantly over that of the Mk1.
- He confirmed that the intake size will go up by approx. 10 mm for the Mk2.
- There is a LOT of work that is required to be done due to engine change. This is something jingos must keep in mind since jingos keep asking if this or that engine can be used or not on a platform..pumps, motors, fuel supply lines, nearly everything associated with the engine requires re-design due to an engine change due to higher fuel flow rates for a larger engine and the different specs of the power generation on board. Plus, the higher weight means localized structural strengthening as well, all of which takes time
- N-LCA will be an out and out 9G fighter. He was categorical about this.
- NP1 trainer doesn’t have a radar- the radome is used for carrying avionics. He said he was more interested in the NP2 since it was the first fighter and was going to carry the same radar as that on the Sea Harrier. I tried to quiz him on this because the Elta 2032 on the Sea Harrier is not the same as the Elta 2032/MMR on the Tejas Mk1, but he didn’t stop what he was saying.
- NP2 is basically similar to the NP1, but with the rear seater’s canopy painted over (he said that! I asked if it was faired over and he said no, just painted over). The rear seater’s space will carry avionics (that were put into the radome on the NP1) and additional fuel tank.
- NP1’s LEVCONS will be initially having 3 positions- 10 deg, 20 deg and 30 deg, just like flap settings. I tried to ask him if the LEVCONS would be just lift generating surfaces or that they could be used as additional control surfaces by the FBW FCS to increase turn rates but he said that they were primarily required for higher lift when landing and taking off
- They’re working on the hands-free take-off for the N-LCA. He said that it was no big deal and they’ll do it for sure
- Mk2 is to get bigger MFD displays, but he said that even the ones on the Mk1 are actually good and possibly adequate
- One piece of news that will get some jingos happy- he said that he has asked CSIO Chandigarh to develop a frameless HUD instead of the current one. It’ll feature higher FoV and its easier to view through since there is no frame obstructing the pilot’s view.
- DASH HMDS from Elbit for the N-LCA as well. I had initially thought they’d go with the Thales Top Owl-F as on the MiG-29K
- Just as I suspected, I asked him if the current drop tank is transonic- he confirmed that it is. A supersonic tank is being developed to carry about 200 gal. (~750 ltrs)
- Also confirmed that there is nothing wrong with the centerline fuel tank – since we almost never see Tejas Mk1 carry a centerline fuel tank in place of the innermost wing pylon drop tanks. If required, Mk1s can carry drop tank on the centerline station also
- Regarding IFR, it is Cobham that is going to work on it. Asked if it’s a fixed probe, retractable or semi-retractable, it was confirmed to be semi-retractable, like that on the MiG-29UPG. I asked about the lack of internal volume on such a small fighter for even a semi-retractable probe and he said that its going to be a small probe, and they’ll manage to find the space for it
- No OBOGS on Tejas Mk1 or NP1. It’ll be there from Mk2 onwards. Designed by DEBEL and certified by CEMILAC
- Regarding the landing gear, he said it was 1600 kgs over the Tejas Mk1’s landing gear weight initially!! They designed it per MilSpec which was too conservative. Also, in addition to the general Factor of Safety that is needed for Ultimate Loads, they added another Factor of Safety of 1, for a total of 2.5 because it was being done for the first time in India and they were concerned about the design..and used maraging steel which was heavy.
- He clearly said that before the NP1 first flight, none of the OEMs even believed that this program had any future and no one cooperated with them when asked for help. Then, when NP1 flew, they were interested in helping out.
- US Navy is now consulting with them on where to reduce weight, what other materials to use. All the leg work is done here itself though, and no work is being done by foreign OEMs. They are confident of shaving off 1000 kgs and bringing it to 600 kgs over the LCA AF version’s landing gear weight for the N-LCA
- On the N-LCA Mk2 they will change the position of the landing gear and bring it more towards the wing/fuselage joint. The landing gear will then retract into a fairing for that. That will also free up space in the fuselage for additional fuel
- Regarding radar, he said that they are pretty confident about it. The reason is that they’re using the same Elta 2032 as on the Sea Harrier! Since they’ve already qualified that radar for the Derby, he was pretty confident about the Derby on the N-LCA. Asked about the Python-V he said that it’s the R-73 that’ll be the WVR weapon..when I asked him how come the Python V was shown on the mockup outside, he said it’s just a mockup. Wasn’t very clear about this
- Shockingly about the radar, when I asked about what increased range one might get with the Elta 2032 since the diameter of the antenna on the N-LCA will be bigger than that on the LUSH SHar, he replied that there is no increase in range, its more than sufficient..I asked him specifically again that “really same detection range?” and he said yes. Again not very clear about this
- When quizzed about AESA for the N-LCA Mk2, he said that for now it’s the same Elta 2032 and Cmde Mao had recently even gone to Israel to test the radar that will be used on the N-LCA Mk2. Here, he mentioned that “if you get anything from Israel, just take it. Their equipment is very good”. Then went on to mention how the Barak was tested on the Viraat and was successful on its very first trial with 2 missiles fired. The first hit the target and the second hit its debris!
- He confirmed that the anti-ship missile for the N-LCA is going to be the Kh-35E, similar to the MiG-29K. Laughed when recollecting how poor the Sea Eagle was as an AShM.
- Primary role envisaged for the N-LCA is that of CAP and Fleet Defence, replacing the Sea Harrier. He was quite dismissive about the P-3C Orion threat (jokingly saying that to shoot that down, a gun is enough!:P), but was primarily concerned about the cruise missile and anti-ship missile threat to the Carrier. But he mentioned that a Carrier Battle Group consists of several rings of protection for the carrier, and that the carrier will get warned about any possible airborne threat several hundred kms before it even approached it. With that much warning, a N-LCA could dash to the edge of the fleet and take on the threat.
- When I asked him if shooting down sub-sonic anti-ship missiles with on-board missiles was a possible scenario for the N-LCA, he replied in the affirmative
- When he mentioned this, I asked him how good the Elta 2032 was with regards to dealing with sea clutter and he said that its very good.
- NP2 is currently already going through integration tests. Will likely fly in June or July if no issues are found.
- NP1 has given them a lot of data for how the platform behaves in 4 flights itself
- Said how the LCA is designed as per the Test Pilot’s recommendations- whatever they want, ADA/HAL give it to them. He said let the IAF get the Rafale and then ask for these small changes and then they’ll figure out just how hard it is to get anything they want. On the N-LCA, we can integrate whatever we want, and for the entire lifetime of the fighter. Easier upgrades will be available since everything is known about the aircraft to the designers

I had to leave at this point since my friend who I’d met after 6 years was in a hurry to leave so we could escape the impending traffic snarl. Thanked the Cmdr profusely and got his card as well. I asked for some other brochures on the Mk2 and he said that he could give me a soft copy of it. To date, I’ve never had so much come from a single conversation at any airshow or business show. Very competent fellows are working on these programs. They need our support and encouragement. Those who are constantly piling it on them, with negative reports are basically doing this nation a great dis-service. Criticize the organization perhaps for its failings, but those who are working on these programs are to be commended and encouraged.


Looking forward to latest updates from Aero India 2015!

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Re: LCA Tejas: News and Discussions

Postby Yagnasri » 11 Feb 2015 08:23

One set of words "what ever they want, HAL/ADA give it to them". Hope the babus and their boss MP note that.

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Re: LCA Tejas: News and Discussions

Postby tushar_m » 11 Feb 2015 08:30

The one thing i want to point out is that LCA Navy with a single nose wheel would mean its not designed to be catapulted from INS Vishal !!!!(speculating)

F-18 rafale etc all have double nose wheel which is favorable for catapult launch.

The only reference i could find for any aircraft that uses separate nose wheels for different versions is F-35.(not comparing just giving examples).

here are the examples

http://defense-update.com/wp-content/up ... ing960.jpg

http://upload.wikimedia.org/wikipedia/c ... asp_(LHD_1).jpg

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Re: LCA Tejas: News and Discussions

Postby brar_w » 11 Feb 2015 09:34

The Charlie JSF requires that arrangement (two wheel) to straddle the cat kit. The wheels are the same although the tires are different from the Beach or the A. Overall a relatively simple modification.

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Re: LCA Tejas: News and Discussions

Postby putnanja » 11 Feb 2015 09:39

From Shiv Aroor's blog PART 2: The Four 'Fixes' After LCA Navy's Ski-Jump Flight

...
Two areas the team is focusing on fixing with all its resources:


1. The Control Law and Flight Control System (FCS) Software needs additional coding and updating to handle the higher performance of the platform. "This will enable extracting the best performance of the aircraft in a safe manner as the margins are progressively reduced," say sources on the team.

2. The second take-away was mechanical, and just as crucial: the NP1's nose landing gear extension routine was faster than predicted or expected. Sources on the team confirm that, "Minor modifications to the nose landing gear are in progress and would be available on the aircraft by end Jan 15."

3. Another lesson learned, according to team sources, is that design teams will need to be "even more pragmatic in keeping margins as excess reserves get compounded and could lead to load exceedence."

4. The team is also considering excessive airspeed to be something to look out for. "While on first appearances, excessive airspeed appears to be harmless, it could aggravate aircraft control problems if flight control failures are encountered," team sources said.

...

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Re: LCA Tejas: News and Discussions

Postby Shreeman » 11 Feb 2015 10:13

^^^ The perfection in the art of writing words without actually conveying any information. Can someone decypher what might be actually meant here? Digital control laws are apprpximations and can always be improved. I am not sure what 2,3,4 even mean. What is not worKing, what is the goal, how would it be achieved?

edit -- from elsewhere, a nice bichhar,
Image

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Re: LCA Tejas: News and Discussions

Postby sattili » 11 Feb 2015 11:57

Shreeman wrote:^^^ The perfection in the art of writing words without actually conveying any information. Can someone decypher what might be actually meant here? Digital control laws are apprpximations and can always be improved. I am not sure what 2,3,4 even mean. What is not worKing, what is the goal, how would it be achieved?


Shreeman ji, let me take a stab at it from a layman perspective. Indranil or other aero gurus can provide more accurate interpretation.

From a project management perspective any unexpected outcome other than the designed/planned one is a risk. It could be either positive or negative. This is what PMI defines positive risk as:

Code: Select all

 Positive risk is the chance that your objectives will produce too much of a good thing. Positive risks are deemed as undesirable despite being positive at face value.

Coming to NP1 SBTF test results I infer that:

#2 - NP1 nose landing gear extended/opened up faster than anticipated. This could pose risk to the aircraft stability hence they will modify the landing gear to have more controlled extension regime aka slow down its opening.

#4- NP1 achieved higher speed during the ski-jump take off than anticipated. What they are saying is this would appear positive on the face value, however this might pose risk for controlling the aircraft incase of scenarios where some flight systems might have failed.

#3- This is infact what I tell all my PMs, don't pad your estimates so that you err on the positive side. We need to stay in a narrow margin on either side of the design goal. This is very critical in Aerospace industry as anything uncontrolled whether its positive or negative is undesirable. So the design engineers need to tighten up their estimates.

Sorry if I didn't make any sense at all :)

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Re: LCA Tejas: News and Discussions

Postby Shreeman » 11 Feb 2015 13:30

Thank you, Sattili. It does help.

For #4, numbers have been reported before. Now the throttle controls (unless its automatic take off) the thrust, speed. Are they going to try to take off at less than full throttle? Also, NP2 (minus pilot2, ejection seat 2, displays, electronics, life support) will be considerably lighter. What does this mean for NP2? Given that take off numbers were public already, why not just provide a target instead of the mumbo jumbo?

For #3, what are we talking about -- 5% or 20%? What is load exceedance? And when does it occur?

#2 seems so minor, I wonder why it made the list at all. Did the main carriage just drop down in one shot? And I am still hoping for some sense of what #1 entails, I thought with FOC being talked of openly, at least IOC type control would be available for NPs too. Does this point to the whole incorporation of levcons aspect that has been left out so far?

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Re: LCA Tejas: News and Discussions

Postby shiv » 11 Feb 2015 13:57

putnanja wrote:From Shiv Aroor's blog PART 2: The Four 'Fixes' After LCA Navy's Ski-Jump Flight
3. Another lesson learned, according to team sources, is that design teams will need to be "even more pragmatic in keeping margins as excess reserves get compounded and could lead to load exceedence."


...
[/quote]
Conversation with Maolankar in Aero India 2011: The landing gear was made to withstand descent rates far greater than necessary and was therefore heavier. Because it was heavier and designed for heavier bangs the actual fuselage frame to which it was attached was also thicker and heavier than and the actuators etc were also bigger and heavier. That is how excess safety margins get compounded. If they could find out exactly how much strength is "just enough" they could cut down landing gear weight and that would lead on do decreasing the weight/strength of all the things associated with the landing gear.

At that time they did not know exactly how much was optimal, and how much was too much

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Re: LCA Tejas: News and Discussions

Postby Shreeman » 11 Feb 2015 14:00

^^ Are they talking about redesigning the mechanism or just how it operates up/down now?

I have seen pictures of landing gear test rigs and tailhook test rigs. It cant be 2x overdesigned after all that testing.

edit -- the consensus appears to be a redesign of the mechanism based on real observations. That could be a time costly exercise.
Last edited by Shreeman on 11 Feb 2015 14:21, edited 1 time in total.

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Re: LCA Tejas: News and Discussions

Postby Karan M » 11 Feb 2015 14:11

It can be, if you are inexperienced and nobody wants to risk a crash, so everything gets padded.

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Re: LCA Tejas: News and Discussions

Postby shiv » 11 Feb 2015 14:39

Shreeman wrote:^^ Are they talking about redesigning the mechanism or just how it operates up/down now?

I have seen pictures of landing gear test rigs and tailhook test rigs. It cant be 2x overdesigned after all that testing.

edit -- the consensus appears to be a redesign of the mechanism based on real observations. That could be a time costly exercise.

Weight. Thickness tolerances load bearing etc/. No consultant would share the info.

I can't recall the figures Maolankaar quoted but it was something like "We did not know whether to design the gear to with stand a maximum of X meters per sec descent or less than that. For safety there was overdesign leading to an excessively heavy landing gear and also an excessively strong frame to take the loads of the extra safety margins of high descent rate. If descent rate could be less then everything can be lighter - but no one shares the info

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Re: LCA Tejas: News and Discussions

Postby negi » 11 Feb 2015 17:34

^ Yep a Mig29k cracked it's spine while landing because it engaged the arrestor with nose a bit too high and then landed too hard on it's nose wheel and cracked the fuselage where LG meets the fuselage.

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Re: LCA Tejas: News and Discussions

Postby vishvak » 11 Feb 2015 18:06

shiv wrote:
Shreeman wrote:^^ Are they talking about redesigning the mechanism or just how it operates up/down now?

I have seen pictures of landing gear test rigs and tailhook test rigs. It cant be 2x overdesigned after all that testing.

edit -- the consensus appears to be a redesign of the mechanism based on real observations. That could be a time costly exercise.

Weight. Thickness tolerances load bearing etc/. No consultant would share the info.

I can't recall the figures Maolankaar quoted but it was something like "We did not know whether to design the gear to with stand a maximum of X meters per sec descent or less than that. For safety there was overdesign leading to an excessively heavy landing gear and also an excessively strong frame to take the loads of the extra safety margins of high descent rate. If descent rate could be less then everything can be lighter - but no one shares the info

Weren't extra features of security and excessively strong frame with extra safety margins designed for exactly that - extra safety margins. The lean and mean landing gear therefore should not become a part of problem instead of part of solution, in which case, logically, the earlier landing gear would be a much better choice. Why would the plane have to change descent rate to be suitable for the landing gear when the landing gear already designed could handle it well already.
From link
..
Basic design changes required to suit the carrier operations are strengthening of aircraft structure and Landing Gear, Arrester Hook, improved engine, enhanced aerodynamic performance and incorporation of special metal/material. A host of other systems like the Leading Edge Vortex Control (LEVCON) surface fitted at the front end of the aircraft wing operated by a concealed rotary actuator with aerodynamic profiling to ensure low landing speed, good controllability and better vision for the pilot. The feature of launch and recovery onboard Carrier at high sink rate of 7.1 rn/sec, flareless landing with engine to full throttle till arrested by deck cable impose five times of loading on Main Landing Gear as compared to the IAF version.

All done already inhouse, gentlemen!

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Re: LCA Tejas: News and Discussions

Postby Indranil » 11 Feb 2015 18:28

putnanja wrote:From Shiv Aroor's blog PART 2: The Four 'Fixes' After LCA Navy's Ski-Jump Flight

...
Two areas the team is focusing on fixing with all its resources:


1. The Control Law and Flight Control System (FCS) Software needs additional coding and updating to handle the higher performance of the platform. "This will enable extracting the best performance of the aircraft in a safe manner as the margins are progressively reduced," say sources on the team.

2. The second take-away was mechanical, and just as crucial: the NP1's nose landing gear extension routine was faster than predicted or expected. Sources on the team confirm that, "Minor modifications to the nose landing gear are in progress and would be available on the aircraft by end Jan 15."

3. Another lesson learned, according to team sources, is that design teams will need to be "even more pragmatic in keeping margins as excess reserves get compounded and could lead to load exceedence."

4. The team is also considering excessive airspeed to be something to look out for. "While on first appearances, excessive airspeed appears to be harmless, it could aggravate aircraft control problems if flight control failures are encountered," team sources said.

...

Good guesses so far. But no, they are talking of something else.

#2. The landing gear of aircraft operating from a aircraft carrier has two major problems. 1. It has to absorb a lot of compressive stress when the aircraft comes in to land. 2. During take off, it has to handle a sudden expansion when the aircraft leaves the ship. This is especially true when working off the skijump as the aircraft does not generate enough lift to support its weight. So one moment it is supporting the whole weight of the aircraft, immediately after leaving the ramp, there is no weight. So the landing gear expands violently. This is known to have created problems on the Harrier for example where the nose landing gear has just fallen off. So they have to make sure that this rate of exapnasion stays under tolerance.

#3. They are actually speaking of the FBW. If you keep too much margin, the commands to the control surface are not correct. On the next control cycle, you have to compensate for this error. This has a way of compounding itself over control cycles, where you start giving the signals for larger and larger deflections. At some point of time, you will exceed the load bearing capability of the hydraulics which move these surfaces.

#4. I don't understand this one completely, but I think this is about safety procedures when things go wrong. Excess speed may create challenges to those procedures.

All-in-all, I did not like this 3 part series. I did not learn anything extra from what Tarmak had expressed in one report. That's okay, at least he did not deride the project for no reason.

Shreeman wrote:edit -- from elsewhere, a nice bichhar,
http://i.imgur.com/pLEYag3.jpg

That is nice! Although, they wouldn't have taken off after that.

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Re: LCA Tejas: News and Discussions

Postby shiv » 11 Feb 2015 18:52

indranilroy wrote:
Shreeman wrote:edit -- from elsewhere, a nice bichhar,
http://i.imgur.com/pLEYag3.jpg

That is nice! Although, they wouldn't have taken off after that.

Why? It's meant for carrier take offs - to attain full power before the "chocks" come off

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Re: LCA Tejas: News and Discussions

Postby Raman » 11 Feb 2015 19:02

I think #4 is about the airspeed during take off. Since this this is completely under automatic software control, sudden gusts, control surface failures, etc. will have to be compensated for by the flight control computers. If the air-speed is too high, the consequent reactions and forces go up by the square of velocity, everything happens much faster and there isn't much altitude to play with. Hence, the air-speed needs to be kept within margins as opposed to rocketing off the deck as fast as possible.

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Re: LCA Tejas: News and Discussions

Postby shiv » 11 Feb 2015 20:05

vishvak wrote:Weren't extra features of security and excessively strong frame with extra safety margins designed for exactly that - extra safety margins. The lean and mean landing gear therefore should not become a part of problem instead of part of solution, in which case, logically, the earlier landing gear would be a much better choice. Why would the plane have to change descent rate to be suitable for the landing gear when the landing gear already designed could handle it well already.!

I can only say what I understood from what Maolankar told me in 2011 before NLCA flew He said the landing gear was probably too strong and therefore too heavy. He did not say that the earlier LCA landing gear was adequate so I cannot comment on that. if you know that to be a fact, there is obviously some information missing because of a disconnect between what you said and what Maolankar said. He only said that the exact strength required was not clearly known and the "compounding effect" was vital because (to use an example - shaving 15 kg off the landing gear would allow the shaving off of maybe another 100 kg from the frame and other structures) These are not the figures he quoted - they are representative of what he said

No mention was made of "changing descent rate". I presumed that descent rate cannot always be controlled exactly and sometimes the plane will bang down hard because of a downdraft combined with an upward lurch of the carrier at the point of touchdown - so the gear has to be strong enough to account for odd exigencies.

Perhaps someone should talk to these people at Aero India next week - I am the wrong person to clear doubts

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Re: LCA Tejas: News and Discussions

Postby jahaju » 11 Feb 2015 20:16

PART 3: The Official LCA Navy Mk.2 Wishlist

The focus on sensor and weapon capability demonstration will be on NP2."

The Mk.2 aims to sport the in-development L-273/Uttam (the project name, incidentally, revealed first on Livefist) active array fire control radar being put together by the DRDO's Electronics & Radar Development Establishment (LRDE). According to official literature, the radar, intended to also be retrofitted on the Mk.1 aircraft that enter service, modes include air-to-air multi-target detection and tracking, multi target air-to-air combat mode, high resolution raid assessment, high Resolution air-to-ground mapping (SAR mode), air to ground ranging, real beam mapping, doppler beam sharpening, ground moving target indication and tracking and terrain avoidance. In air-to-sea mode, sea search and multi target tracking, range signature and inverse synthetic aperture radar will apply. But that's just the radar.

The the No.5 prototype NP5 will be a Mk.1 twin-seat trainer prototype, the construction of which has already begin at HAL. The NP5 was proposed to save time and as a risk mitigation exercise using existing resources and funds.

The MoD is now all set to clear the third and fourth prototypes, NP3 & NP4, both to be single-seat fighter prototypes of the LCA Navy Mk.2, incorporating all airframe and platform changes, including aft fuselage changes to house the new, larger and more powerful General Electric F414-GE-INS6 turbofan engine. Team LCA-N sources confirm that there will be changes in most sections of the airframe.
Last edited by jahaju on 11 Feb 2015 20:19, edited 1 time in total.

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Re: LCA Tejas: News and Discussions

Postby Indranil » 11 Feb 2015 20:18

shiv wrote:
indranilroy wrote:That is nice! Although, they wouldn't have taken off after that.

Why? It's meant for carrier take offs - to attain full power before the "chocks" come off

They will do it when they return in March. ADA is too risk averse. They will not make another flight till they have changed the LG, software etc. to where they are completely comfortable.

Raman wrote:I think #4 is about the airspeed during take off. Since this this is completely under automatic software control, sudden gusts, control surface failures, etc. will have to be compensated for by the flight control computers. If the air-speed is too high, the consequent reactions and forces go up by the square of velocity, everything happens much faster and there isn't much altitude to play with. Hence, the air-speed needs to be kept within margins as opposed to rocketing off the deck as fast as possible.

That is kind of what I guess too.

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Re: LCA Tejas: News and Discussions

Postby Karan M » 11 Feb 2015 20:27

If LRDE gets all those modes onto the radar, true gamechanger across platforms & upgrades.

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Re: LCA Tejas: News and Discussions

Postby putnanja » 12 Feb 2015 00:12

LCA-MkII specs from tarmak's twitter handle @writetake

Image

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Re: LCA Tejas: News and Discussions

Postby Khalsa » 12 Feb 2015 00:34

FROM THE SIDE
Image

FROM THE BACK

Image

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Re: LCA Tejas: News and Discussions

Postby PratikDas » 12 Feb 2015 00:39

putnanja wrote:LCA-MkII specs from tarmak's twitter handle @writetake

Image

^^^ Interesting that it doesn't mention in-flight refueling capability

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Re: LCA Tejas: News and Discussions

Postby Khalsa » 12 Feb 2015 00:41

negi wrote:^ Yep a Mig29k cracked it's spine while landing because it engaged the arrestor with nose a bit too high and then landed too hard on it's nose wheel and cracked the fuselage where LG meets the fuselage.


We do it Top Gun Eestyle and still nothing breaks.
https://vine.co/v/MThEVdEZ9eE

Excellent video that displays some of the forces that come into play when a Mig-29 gets arrested although the rear wheels touched first so this is a damn good landing.
Last edited by Khalsa on 12 Feb 2015 07:01, edited 2 times in total.

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Re: LCA Tejas: News and Discussions

Postby shravanp » 12 Feb 2015 00:45

noobie pooch. Is N-LCA going to go for folded wings in future?

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Re: LCA Tejas: News and Discussions

Postby Sid » 12 Feb 2015 00:58

They are practically swapping everything in MK II!! Why?? No way in hell MK Ii can have FOC before 2025 with all these changes.

It will have same skin but new soul.

This should have been called Super LCA, noy MK II. Even damn Typhoon only recently started to drop LGBs, yet they make it look like they they have fired photon torpedoes.

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Re: LCA Tejas: News and Discussions

Postby Indranil » 12 Feb 2015 01:15

skekatpuray wrote:noobie pooch. Is N-LCA going to go for folded wings in future?

Baba, how many times has this got to be repeated? The answer is no.

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Re: LCA Tejas: News and Discussions

Postby shravanp » 12 Feb 2015 02:18

indranilroy wrote:
skekatpuray wrote:noobie pooch. Is N-LCA going to go for folded wings in future?

Baba, how many times has this got to be repeated? The answer is no.


Sorry saar...I missed it.

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Re: LCA Tejas: News and Discussions

Postby putnanja » 12 Feb 2015 02:29

for the technical gurus here, how much improvement does a 0.5m plug make to the aerodynamics of the LCA? It doesn't seem to be much.

I believe one of the plans for Mk-II is also to rearrange the stuff inside to use the space optimally, as things have changed since Mk-I was finalized.

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Re: LCA Tejas: News and Discussions

Postby Viv S » 12 Feb 2015 06:02

Sid wrote:This should have been called Super LCA, noy MK II. Even damn Typhoon only recently started to drop LGBs, yet they make it look like they they have fired photon torpedoes.


Actually its been able to drop LGBs since 2008 (austere Litening III retrofit on the T1s). The P1E upgrade on the other hand was the final stage of integration after which the aircraft could employ upto six LGBs in a single pass, with a variety of fusing options and programmable trajectories.

But nitpicks aside, you're right. The Tejas Mk2 is a rather thorough refresh of the system and FOC before 2025 is far from a given. The Mk1 can perform the majority of typical missions performed by the air force from day one with a precision strike capability that took the Eurofighter and Rafale close to a decade to incorporate.


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Re: LCA Tejas: News and Discussions

Postby putnanja » 12 Feb 2015 09:47

Video of NLCA-NP2 first flight, posted on Tejas FB...


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Re: LCA Tejas: News and Discussions

Postby Prasad » 12 Feb 2015 10:39

Sweet video from tarmak including NP-? takeoff from SBTF! I don't have to tell you to watch in HD.


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Re: LCA Tejas: News and Discussions

Postby srin » 12 Feb 2015 11:46

I didn't see air-brakes deployed upon landing in NP-2. Have they shifted the air brakes like they wanted to, or have they removed it in the LCA Navy completely ?

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Re: LCA Tejas: News and Discussions

Postby sooraj » 12 Feb 2015 11:58

any details on the equipments on the second seat!

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Re: LCA Tejas: News and Discussions

Postby srai » 12 Feb 2015 14:51

putnanja wrote:Video of NLCA-NP2 first flight, posted on Tejas FB...



In hindsight, this should have been LCA's first design. This would have allowed 1 airframe design to cater to all needs with minor mods for the IAF, IN and trainer variants.


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