LCA News and Discussions

SaiK · Post by **SaiK** » 26 Jun 2013 18:07

still, it does not qualify as a technical answer for which we have to wait for the experts to arrive.

JayS · Post by **JayS** » 26 Jun 2013 19:15

^^^ I am not an expert, but Will try and test my knowledge here.

Levcon were introduced in NLCA for catering its low-speed-high-AoA STOBAR requirements. Levcon work similar to LERX (e.g. F-18). It produces a leading edge vortex over the wing at high AoA. Due to this a low-pressure zone is created over the upper surface of the wing which adds to the overall lift as well as it delays the stall. So, with levcon/LERX an aircraft can produce higher lift at given AoA (Note: in the higher AoA region only) and can achieve higher critical AoA, in turn reducing the stall speed. This helps in STOBAR obviously. To me it seems easiest fix for the problem without measure design changes.

Same is not required for AF version. So why put additional weight?? yes, one wonders it would increase high-AoA characteristics on LCA too. In this CEMILAC paper (drdo.gov.in/drdo/pub/dss/2009/main/2-CEMILAC.pdf‎) It is mentioned that:

Leading Edge Controller (Levcon) is an secondary control surface located at the leading edge of the wing
and the fuselage. The Levcon is initially planned in LCA Navy for the low landing speed capability and other cruise
performance. An important requirement of a fighter aircraft is the Sustained Turn Rate (STR). The fighter variant of
Tejas is not meeting the STR requirement of ASR. The STR is a strong function of the aerodynamic efficiency. From
the wind tunnel results it was found that the Levcon produce higher L/D (Fig. 17). A detailed study to implement Levcon
in fighter and identification of other design constraints is under progress.

But nothing heard of it afterwards. May be ADA must have felt it unnecessary.

I vaguely remember to have read that the Levcon on NLCA is snapped to 3 settings 10, 20, 30 deg. And its deflection is +30 and -20 deg. Can anybody confirm if this is true.

member_26965 · Post by **member_26965** » 26 Jun 2013 19:41

LEVCONS on NLCA is for low landing speeds, better control and hence aids visibility while carrier landing. This is defined use and not what Levcon general definition is. LCA AF has not use for it.

suryag · Post by **suryag** » 26 Jun 2013 20:58

Let me give my expert opinion here, the levcon is for aesthetic purpose and it is on N-LCA because someone complained LCA was not brawny enough

suryag · Post by **suryag** » 26 Jun 2013 21:04

Flight test update

From

LCA-Tejas has completed 2228 Test Flights Successfully. (24-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-142,LSP4-85,LSP5-187,LSP7-47,NP1-4,LSP8-13)

to

LCA-Tejas has completed 2234 Test Flights Successfully. (25-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-144,LSP4-85,LSP5-188,LSP7-48,NP1-4,LSP8-15)

pralay · Post by **pralay** » 26 Jun 2013 22:23

6 test flights a day is looks nice. I wish they had managed such rate earlier.

ramana · Post by **ramana** » 26 Jun 2013 22:28

Well when are the real milestone flights being conducted?

Wake penetration test etc?

Without knowing the objectives of those flights ti become a numbers statistics watch.

We dont even know how many combined flight hours all thse flights are?
Long ago there were some notional goals for number of flight hours before IOC.

But still greatful for the updates/data being provided!

We can get an idea from the configurations of
LSP-3,7 & 8 which seem to be the only ones flying at incremental flights of one to two.

fanne · Post by **fanne** » 26 Jun 2013 22:34

So from memory LSP-3 is where MMR is (don't know if later versions have them or not). I would speculate it is for Radar testing (or could be anything). LSP-7 and LSP-8 is near production standards so weight saving, CLAW tunning, how various componenents work etc would be going there. Don't know if any of these are for exapnding the flight profile. I believe PV-3 was used for that. LSP-6 is ofcourse spin test.

suryag · Post by **suryag** » 27 Jun 2013 01:11

All birds after LSP3 have the radar and CMDS <pure speculation>Most likely radar testing in different modes and different target locations and range</pure speculation>

member_23651 · Post by **member_23651** » 27 Jun 2013 01:39

nileshjr wrote:^^^ I am not an expert, but Will try and test my knowledge here.

Levcon were introduced in NLCA for catering its low-speed-high-AoA STOBAR requirements. Levcon work similar to LERX (e.g. F-18). It produces a leading edge vortex over the wing at high AoA. Due to this a low-pressure zone is created over the upper surface of the wing which adds to the overall lift as well as it delays the stall. So, with levcon/LERX an aircraft can produce higher lift at given AoA (Note: in the higher AoA region only) and can achieve higher critical AoA, in turn reducing the stall speed. This helps in STOBAR obviously. To me it seems easiest fix for the problem without measure design changes.

Same is not required for AF version. So why put additional weight?? yes, one wonders it would increase high-AoA characteristics on LCA too. In this CEMILAC paper (drdo.gov.in/drdo/pub/dss/2009/main/2-CEMILAC.pdf‎) It is mentioned that:

Leading Edge Controller (Levcon) is an secondary control surface located at the leading edge of the wing
and the fuselage. The Levcon is initially planned in LCA Navy for the low landing speed capability and other cruise
performance. An important requirement of a fighter aircraft is the Sustained Turn Rate (STR). The fighter variant of
Tejas is not meeting the STR requirement of ASR. The STR is a strong function of the aerodynamic efficiency. From
the wind tunnel results it was found that the Levcon produce higher L/D (Fig. 17). A detailed study to implement Levcon
in fighter and identification of other design constraints is under progress.
But nothing heard of it afterwards. May be ADA must have felt it unnecessary.

I vaguely remember to have read that the Levcon on NLCA is snapped to 3 settings 10, 20, 30 deg. And its deflection is +30 and -20 deg. Can anybody confirm if this is true.

Thanks Nilesh, exactly I also thought that Levcons could be used as canards(ala PAK FA). The snippet you quoted hints that it might affect STR in positive way, but for that they had to do some tests. Now it could be time constraint too, because adding levcons and using them canards would have been used, would mean rewriting of flight control s/w and revalidation of the same. Which would have delayed LCA MK 2, which might be unacceptable to stake holders

SaiK · Post by **SaiK** » 27 Jun 2013 03:06

If one goes by previous reports, the focus areas should be
- A2G / SAR, with various clutter model
- BVR / max range yet done.. waiting for Astra integration
- have we covered WVR non-heat seeker types?, that needs cuing and guidance /not fire&forget types.

what else was on the Mk-1 profile?

symontk · Post by **symontk** » 27 Jun 2013 06:50

two days back I saw the Avro hack too flying

Indranil · Post by **Indranil** » 27 Jun 2013 06:59

nileshjr wrote:^^^ I am not an expert, but Will try and test my knowledge here.

Levcon were introduced in NLCA for catering its low-speed-high-AoA STOBAR requirements. Levcon work similar to LERX (e.g. F-18). It produces a leading edge vortex over the wing at high AoA. Due to this a low-pressure zone is created over the upper surface of the wing which adds to the overall lift as well as it delays the stall. So, with levcon/LERX an aircraft can produce higher lift at given AoA (Note: in the higher AoA region only) and can achieve higher critical AoA, in turn reducing the stall speed. This helps in STOBAR obviously. To me it seems easiest fix for the problem without measure design changes.

Same is not required for AF version. So why put additional weight?? yes, one wonders it would increase high-AoA characteristics on LCA too. In this CEMILAC paper (drdo.gov.in/drdo/pub/dss/2009/main/2-CEMILAC.pdf‎) It is mentioned that:

Leading Edge Controller (Levcon) is an secondary control surface located at the leading edge of the wing
and the fuselage. The Levcon is initially planned in LCA Navy for the low landing speed capability and other cruise
performance. An important requirement of a fighter aircraft is the Sustained Turn Rate (STR). The fighter variant of
Tejas is not meeting the STR requirement of ASR. The STR is a strong function of the aerodynamic efficiency. From
the wind tunnel results it was found that the Levcon produce higher L/D (Fig. 17). A detailed study to implement Levcon
in fighter and identification of other design constraints is under progress.
But nothing heard of it afterwards. May be ADA must have felt it unnecessary.

I vaguely remember to have read that the Levcon on NLCA is snapped to 3 settings 10, 20, 30 deg. And its deflection is +30 and -20 deg. Can anybody confirm if this is true.

You are right on all accounts here, the purpose of levcons and their current settings. Also I agree that the Levcon can be used for better STR (if the need arises and the priorities allow time). They can be easily strapped on later.

There is some confusion about the STR achieved by LCA Mk-1. The CEMILAC paper (and many other commentators) said that it falls short of the ASR. But recently there was confirmation that LCA did achieve the STR specified by the ASR. There is a possibility that the requirement was diluted.

ranji wrote:LEVCONS on NLCA is for low landing speeds, better control and hence aids visibility while carrier landing. This is defined use and not what Levcon general definition is. LCA AF has not use for it.

The bolded part is wrong. if you have higher AoA your nose obstructs the view more. That's why they had to droop the nose. Also, the defined use can be extended. When you have the hardware, why not use it.

suryag wrote:Let me give my expert opinion here, the levcon is for aesthetic purpose and it is on N-LCA because someone complained LCA was not brawny enough

Right

member_26965 · Post by **member_26965** » 27 Jun 2013 08:11

indranilroy wrote:
ranji wrote:LEVCONS on NLCA is for low landing speeds, better control and hence aids visibility while carrier landing. This is defined use and not what Levcon general definition is. LCA AF has not use for it.
The bolded part is wrong. if you have higher AoA your nose obstructs the view more. That's why they had to droop the nose. Also, the defined use can be extended. When you have the hardware, why not use it.

Node droop, and extended use is not unrelated to current situation. Aircraft landing at lower speeds, good control over aircraft and visibility for pilot is defined by ADA. It will be good to stick to it instead of hypothesis.

Indranil · Post by **Indranil** » 27 Jun 2013 10:00

ranji wrote: Node droop, and extended use is not unrelated to current situation. Aircraft landing at lower speeds, good control over aircraft and visibility for pilot is defined by ADA. It will be good to stick to it instead of hypothesis.

Sorry boss, you have lost me. I see keywords strung in a sentence which does not make any cogent sense to me.

JayS · Post by **JayS** » 27 Jun 2013 11:16

AnantS wrote: Thanks Nilesh, exactly I also thought that Levcons could be used as canards(ala PAK FA). The snippet you quoted hints that it might affect STR in positive way, but for that they had to do some tests. Now it could be time constraint too, because adding levcons and using them canards would have been used, would mean rewriting of flight control s/w and revalidation of the same. Which would have delayed LCA MK 2, which might be unacceptable to stake holders

I am trying to dig out more technical info on this. I am sure ADA must have considered application of LEVCONs even for LCA in early stages as they considered canards. I am trying to speculate what could be the rationale behind ADA's decisions. So take it with a pintch of salt.

There is a profound difference in what is called as "Canards"(classically, its a fore-plan (vis-a-vis a tail plan) to counter the negative lateral stability of the wing and avoid deep stall apart from many other advantages) and "LEVCON" (which is basically a LERX device but its like a slat). Canards produce their own lift and also leading edge vortices in case they are close-coupled with the wings. Where as LEVCONs increase the lift based on leading edge vortices as well as change in camber much like slats.

Measure advantages with LEVCON is they are snap-fitted with the wing leading edges. No, trailing or side edges so no downwash. Less drag as compared to canards and also less RCS. Plus in normal flight you can simply put it in neutral and no side effects, no trim losses. Unlike canards which can be useful in the whole AoA range LEVCONs are effective only in high AoA ranges. Also a canard produces significant lift and so a significant pitching-up moment. For an already unstable plane this increases the amount of trimming efforts even further. OTOH, LEVCONs produce minimal pitching up moment (They basically increase the effective lift of the wing itself and thus minimal change in position of Center of Lift). LEVCONs are simple to position as well, does not hamper visibility of the pilot, and do not take much space either. Their main role it to increase th ease at which the plane can take-off and land. Canards can have rather larger usability. So i think, ADA must have chosen the simpler solution rather than something like canards to address NLCA's issues. And the associated side-effects (increased drag, reduced RCS, additional weight, added complexity in FCS, additional testing requirements etc) might have tilted the scale away from LEVCONs for AF version of LCA.

A request: Can anybody get this paper from somehow?? http://arc.aiaa.org/doi/abs/10.2514/6.2008-336 Its from ADA guys. Looks like it contains the details of LEVCON for NLCA. It would be great to read this one. Anyone??
Some more papers: http://link.springer.com/content/pdf/10 ... -6_181.pdf
http://arc.aiaa.org/doi/abs/10.2514/6.1996-2501

suryag · Post by **suryag** » 27 Jun 2013 11:26

Flight test update

From

LCA-Tejas has completed 2234 Test Flights Successfully. (25-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-144,LSP4-85,LSP5-188,LSP7-48,NP1-4,LSP8-15)

to

LCA-Tejas has completed 2235 Test Flights Successfully. (25-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-144,LSP4-86,LSP5-188,LSP7-48,NP1-4,LSP8-15)

member_26965 · Post by **member_26965** » 27 Jun 2013 11:34

indranilroy wrote:Sorry boss, you have lost me. I see keywords strung in a sentence which does not make any cogent sense to me.

Ditto, what you say is absolutely beyond my comprehension.

JayS · Post by **JayS** » 27 Jun 2013 13:41

indranilroy wrote: You are right on all accounts here, the purpose of levcons and their current settings. Also I agree that the Levcon can be used for better STR (if the need arises and the priorities allow time). They can be easily strapped on later.

Indranil, could you please explain what is the use of LEVCON with upward (+30) deflection?? Downward deflection of -20deg is obviously for STOBAR which increases lift. Can't think of use of upward deflection.

vasu raya · Post by **vasu raya** » 27 Jun 2013 14:40

Believe the Tejas in yellow primer is for testing the new Radome, since it was accompanied by a Jag, most likely its the air to ground mode of the radar that is being calibrated. Radome performance was in question for IOC-2.

Indranil · Post by **Indranil** » 27 Jun 2013 16:35

nileshjr wrote:
indranilroy wrote: You are right on all accounts here, the purpose of levcons and their current settings. Also I agree that the Levcon can be used for better STR (if the need arises and the priorities allow time). They can be easily strapped on later.
Indranil, could you please explain what is the use of LEVCON with upward (+30) deflection?? Downward deflection of -20deg is obviously for STOBAR which increases lift. Can't think of use of upward deflection.

Actually, downward deflections are +ve and upward positions are -ve. The upward deflection is for drag enhancement (You probably guessed it, but didn't believe it

)

Wind tunnel tests on 1:15 scale LCA Airforce model with LEVCON 0 deg, 10 deg, 20 deg and 30 deg in 1.2m tunnel

Abstract
Wind tunnel tests were carried out on 1:15 scale flow-through model of LCA with different leading edge slat angles and different levcon angles to see the effect of control devices at different Mach numbers. Wind tunnel tests were carried out by using Twin Roll Model Support system to achieve the higher angles of attack. Tests were carried out in the Mach number range of 0.3 to 1.60 and side slip angles of 0 deg, +2.5 deg and +-5 deg. Reynolds number based on mean aerodynamic chord varies from 4.0 to 9.60 million depending on the Mach number. Tests were conducted with different leading edge slat deflections viz., zero, half an full slat combinations with different Levcon angles 0 deg, 10 deg, 20 deg and -30 deg. Results indicate that, Levcon (0 deg, 10 deg and 20 deg)with zero slat configuration shows change in lift slope around a=10 deg, where as with half and full slats do not show any variation in the range of angle of attack tested. Levcon (0 deg, 10 deg and 20 deg) in combination with leading edge slats of zero, half and full decrease the axial force and drag characteristics with incidence. Levcon (-30 deg) configuration assessed as a drag enhancing device gives rise to higher axial force and drag component.

Also, your research in the working of the Levcon is going in the right direction. Please accept my compliments for doing your research before posting. Unfortunately, it has become rare at BR these days. But don't ask anybody to post a link to those papers. It is illegal to host them or circulate them personally.

JayS · Post by **JayS** » 27 Jun 2013 19:21

indranilroy wrote: Actually, downward deflections are +ve and upward positions are -ve. The upward deflection is for drag enhancement (You probably guessed it, but didn't believe it )

Also, your research in the working of the Levcon is going in the right direction. Please accept my compliments for doing your research before posting. Unfortunately, it has become rare at BR these days. But don't ask anybody to post a link to those papers. It is illegal to host them or circulate them personally.

Ohh..I was thinking what on earth made ADA have 30 deg upward deflection. Now it makes sense. Downward is positive. As for the upward deflection is concerned, its clear that it increases drag. So is is used as air-breaks?? And I am guessing it does not affect Lift much in this config. I am still a little unclear on how this is used in flight.

Regarding the papers, you are right technically. But i wouldn't mind somebody who has access to them read them and give a overview here.

Ethically speaking I see those papers as "National Treasure" to which we Indians should have free access. But look at the irony, that I can very easily download such reports from NASA/NATO repositories. But for our own reports have to try harder.

Anyways, Thanks for the link, from that I found out where NAL reports are kept. But still the reports are not freely available. I hope Indian research labs publish reports (removing any critical data) for aam junta to be found easily. And if you know such repositories, please share. I hate banging my head on AIAA's door for accessing our own "National Treasure".

Sagar G · Post by **Sagar G** » 27 Jun 2013 19:25

nileshjr wrote:A request: Can anybody get this paper from somehow?? http://arc.aiaa.org/doi/abs/10.2514/6.2008-336 Its from ADA guys. Looks like it contains the details of LEVCON for NLCA. It would be great to read this one. Anyone??
Some more papers: http://link.springer.com/content/pdf/10 ... -6_181.pdf
http://arc.aiaa.org/doi/abs/10.2514/6.1996-2501

The first paper is from 08 and the third one from 96, what I don't understand is why are we allowing the Americans to take a peek into our programs ??? Both these articles are not available in DSJ so if some Indian wishes to read them then he has to pay the Americans for that !!!!! Can someone explain why is it so ???

Though I found this Computational Fluid Dynamics in Aerospace Industry in India

Victor · Post by **Victor** » 27 Jun 2013 19:58

Sagar G wrote: what I don't understand is why are we allowing the Americans to take a peek into our programs ??? Both these articles are not available in DSJ so if some Indian wishes to read them then he has to pay the Americans for that !!!!! Can someone explain why is it so ???

That's because the Americans must have threatened to activate kill switches on the LCA's engines (GE F404 & 414) if we don't share all of the LCA's secrets with them. The best way to comply without seeming like sellouts is to post it in a science journal website where any request from non-Americans (CIA/NSA/DIA/TFTA only) can be denied. The easily available pdfs like the one you have provided are put out to feed disinformation to the paki net squads who do 24/7 photochor all over the web like their brudder chinese.

ramana · Post by **ramana** » 27 Jun 2013 20:17

What about IDSA reports which used to be available free are now charged by Routledge!

NRao · Post by **NRao** » 27 Jun 2013 21:11

so if some Indian wishes to read them then he has to pay the Americans for that !!!!!

Or ask the authors for a copy. The Journals should not mind that - or at least they never used to mind that.

Alternatively the authors can publish the paper in an Indian journal.

Or check with your local/college library, they may (mine does) have access to such journals.

Kartik · Post by **Kartik** » 28 Jun 2013 10:41

vasu raya wrote:Believe the Tejas in yellow primer is for testing the new Radome, since it was accompanied by a Jag, most likely its the air to ground mode of the radar that is being calibrated. Radome performance was in question for IOC-2.

how can you surmise that? A new radome can be tested on any of the existing prototypes, even if they have been painted.

Kartik · Post by **Kartik** » 28 Jun 2013 10:42

ranji wrote:
indranilroy wrote:Sorry boss, you have lost me. I see keywords strung in a sentence which does not make any cogent sense to me.
Ditto, what you say is absolutely beyond my comprehension.

that really reflects badly on you ranji..Indranil has to be one of the most effective communicators on BRF. I don't believe you'll find anyone else on BRF agreeing with you.

suryag · Post by **suryag** » 28 Jun 2013 11:30

Ranji - btw IRji is a very respected poster here and no offence to your posts either but let us not be condescending towards one another.

BTw Livefist carrying AC's interview on LCA

http://www.livefistdefence.com/2013/06/ ... -full.html

The first two to three full-rate production LCA Tejas Mk.1 fighters for the Indian Air Force will roll out HAL's production facility in Bangalore in December, marking a major milestone in the trouble's programme's final leg. The aircraft will be the first of an order of 40 placed by the IAF of the Mk.1 variant slated to enter squadron service by the end of next year.

In an exclusive interview to Livefist, the DRDO's new chief Dr Avinash Chander, said, "I feel very confident that LCA is within a visible range for production start. The target is that production should start this year. We should see two-three aircraft rolling out this year itself."

After taking over as the DRDO's new chief last month following years at the Advanced Systems Laboratory (ASL), where he found renown as the spearhead of the Agni strategic missile programme, one of the first things that Dr Chander did in his new capacity was fly down to Bangalore and chair a series of meetings with officials from the Aeronautical Development Agency (ADA), CEMILAC, National Fight Test Centre, HAL and the handful of other agencies involved in the development and certification of the LCA Tejas. His message was simple, yet clear: the air force, and indeed the country, would not wait any longer than the end of next year for the Mk.1. He told them, in no uncertain terms, that the next 18 months needed to be the fight of their lives. No excuses. Tejas needed to leave the DRDO stable, he impressed, because there were bigger, more challenging aircraft to build for the IAF. The DRDO, he told them, simply couldn't be stalled with the programme any longer.

With over 2,200 test sorties on the board, the Tejas has 140 hours of test flying left before it achieves the second phase of its initial operational clearance (IOC-2), indicates Dr Chander, a special set of test points deferred from the first in January 2011. "The residual tasks are quite minimal. Some weapon release trials we have to do, some modifications we have done need to be tested. The radar has to be tested for operations. A total of 140 hours are planned in the next few months for IOC-2. With that the aircraft will be cleared for production."

Final operational clearance (FOC)), the final step before induction into an IAF squadron, is set for November-December 2014. "We will complete the FOC by 2014 end. There are some issues when you touch the boundaries of performance, which have been identified and come out only during flight test. Those will be rectified. For FOC, there will be a variety of weapons, all weather clearance."

Right about the time that the Tejas Mk.1 achieves IOC-2, two more naval prototypes will roll out, followed by a first flight before the end of the year. "The test facility is getting ready. I am confident that the LCA Navy will be on schedule," says Dr Chander. The first prototype, which took off in April last year, hasn't flown for nearly a year now, with the platform's undercarriage undergoing a major re-design with the help of EADS as a technological consultant.

"The safety record of the Tejas during testing has been absolutely superb. No other aircraft has this record," Dr Chander says with pride.

The new DRDO chief has asked for an update every alternate day on the LCA programme, and will be briefed by his special team entrusted with keeping things on track over the next 18 months.

vasu raya · Post by **vasu raya** » 28 Jun 2013 12:40

Kartik wrote:
vasu raya wrote:Believe the Tejas in yellow primer is for testing the new Radome, since it was accompanied by a Jag, most likely its the air to ground mode of the radar that is being calibrated. Radome performance was in question for IOC-2.
how can you surmise that? A new radome can be tested on any of the existing prototypes, even if they have been painted.

It doesn't preclude other aircraft carrying the new radome, the yellow primer suggests that its either a brand new aircraft or a revised one like say LSP-3 being brought to the latest standard. The likelihood of either test path sporting a new radome is higher, if a new radome is indeed being tried out. Being close to IOC-2, its time and there was a hint as well in the news of trying out a new radome in the test program.

The Jag as a chase aircraft was about air to ground mode of the MMR (terrain nav is not IOC critical) and here the guess is the Tejas MMR has had issues with its A2G mode, part of it being performance of the radome in ground clutter resolution, its a guess.

member_26965 · Post by **member_26965** » 28 Jun 2013 14:49

Kartik wrote:that really reflects badly on you ranji..Indranil has to be one of the most effective communicators on BRF. I don't believe you'll find anyone else on BRF agreeing with you.

Must be. If I don't understand what he said, I don't understand. He is hypothesizing vs what ADA specifically said. Why Slower speeds and better control won't aid to visibility. I hope he can post facts instead of relying on his communication skills.

JayS · Post by **JayS** » 28 Jun 2013 16:59

ranji wrote:
Kartik wrote:that really reflects badly on you ranji..Indranil has to be one of the most effective communicators on BRF. I don't believe you'll find anyone else on BRF agreeing with you.
Must be. If I don't understand what he said, I don't understand. He is hypothesizing vs what ADA specifically said. Why Slower speeds and better control won't aid to visibility. I hope he can post facts instead of relying on his communication skills.

Could you please explain what exactly you mean by visibility and how "Slower speeds and better control" would aid visibility??

One thing is certain, drooping nose improves visibility in front while landing at high AoA.

Singha · Post by **Singha** » 28 Jun 2013 17:59

livefist

With over 2,200 test sorties on the board, the Tejas has 140 hours of test flying left before it achieves the second phase of its initial operational clearance (IOC-2), indicates Dr Chander, a special set of test points deferred from the first in January 2011. "The residual tasks are quite minimal. Some weapon release trials we have to do, some modifications we have done need to be tested. The radar has to be tested for operations. A total of 140 hours are planned in the next few months for IOC-2. With that the aircraft will be cleared for production."
.............
Right about the time that the Tejas Mk.1 achieves IOC-2, two more naval prototypes will roll out, followed by a first flight before the end of the year. "The test facility is getting ready. I am confident that the LCA Navy will be on schedule," says Dr Chander. The first prototype, which took off in April last year, hasn't flown for nearly a year now, with the platform's undercarriage undergoing a major re-design with the help of EADS as a technological consultant.
.............
The new DRDO chief has asked for an update every alternate day on the LCA programme, and will be briefed by his special team entrusted with keeping things on track over the next 18 months.

member_26965 · Post by **member_26965** » 28 Jun 2013 18:04

nileshjr wrote:Could you please explain what exactly you mean by visibility and how "Slower speeds and better control" would aid visibility??

One thing is certain, drooping nose improves visibility in front while landing at high AoA.

I am merely quoting ADA. The Nose droop dimension was added by the 'respected guy.' It is his responsibility to reply to my query since he claimed what I typed of ADA was wrong. He also hypothesized that LERX can be expanded, which was not specific to the original question why LCA IAF does not has a LERX / LEVCON.

Kartik · Post by **Kartik** » 28 Jun 2013 18:05

vasu raya wrote: It doesn't preclude other aircraft carrying the new radome, the yellow primer suggests that its either a brand new aircraft or a revised one like say LSP-3 being brought to the latest standard. The likelihood of either test path sporting a new radome is higher, if a new radome is indeed being tried out. Being close to IOC-2, its time and there was a hint as well in the news of trying out a new radome in the test program.

The Jag as a chase aircraft was about air to ground mode of the MMR (terrain nav is not IOC critical) and here the guess is the Tejas MMR has had issues with its A2G mode, part of it being performance of the radome in ground clutter resolution, its a guess.

it could just be that LSP-8 is still flying without any paint. The new radome could be retrofitted on any of the existing LSP or even PV prototypes, it isn't much of a hassle.

I didn't get what you mentioned in the second para. Just having a chase aircraft doesn't imply that the A2G modes of the MMR-Elta2032 were being tested.

krishnan · Post by **krishnan** » 28 Jun 2013 18:06

The radar has to be tested for operations....

first official confirmation of radar integration

Singha · Post by **Singha** » 28 Jun 2013 18:35

radar is the highest power draw electrically in the plane. I think it tests the plane electrical distribution system under stress condition. cant be as simple as a household power supply checking with a screwdriver tester and fluke device for sure.

JayS · Post by **JayS** » 28 Jun 2013 19:27

ranji wrote:
nileshjr wrote:Could you please explain what exactly you mean by visibility and how "Slower speeds and better control" would aid visibility??

One thing is certain, drooping nose improves visibility in front while landing at high AoA.
I am merely quoting ADA. The Nose droop dimension was added by the 'respected guy.' It is his responsibility to reply to my query since he claimed what I typed of ADA was wrong. He also hypothesized that LERX can be expanded, which was not specific to the original question why LCA IAF does not has a LERX / LEVCON.

@ranji
All he meant that, not necessarily the advantages of LEVCON are restricted to the given reasons by ADA. ADA might have chosen LEVCON for STOBAR requirements but other uses can always be exploited once you have the hardware in place. Theoretically speaking, LEVCON could boost performance on AF LCA. Even ADA knows this and they have definitely thought about that, which is clear from the CEMILAC paper i quoted few posts back. Its not just LEVCON but LEVCON + wing has to be considered together, so what works for one may not work for other wing.

In fact PAK-FA incorporates LEVCONs for improving maneuverability despite being AF version and the LEVCONs on PAKFA are quite big as compared to NLCA.

LEVCON ==> increased AoA, reduced landing speed, increased controlability (in NLCA)
Nose Droop ==> to mitigate visibility issue due to higher AoA for carrier landing

@others

If LEVCON helps in carrier landing, won't it be helpful in reducing approach speed for AF version, thus reducing landing distance and/or eliminating need of chute breaking?? It also would help in low-speed maneuverability, theoretically, wouldn't it?? Well ADA must have good reasons not to keep LEVCON for at least LCA MK2 AF version. May be they are not as effective just like canards were not for LCA. I wonder why?? JMT

Indranil · Post by **Indranil** » 28 Jun 2013 21:02

All, thanks for your kind words but please don't waste space and time defending my posts.

Ranji, I think you were prejudiced while reading my posts. I request you to read them again. Also, with all due respect, I don't think you have understand what ADA wrote as well. Please consider reading them as well.

nileshjr wrote: @ranji
If LEVCON helps in carrier landing, won't it be helpful in reducing approach speed for AF version, thus reducing landing distance and/or eliminating need of chute breaking?? It also would help in low-speed maneuverability, theoretically, wouldn't it?? Well ADA must have good reasons not to keep LEVCON for at least LCA MK2 AF version. May be they are not as effective just like canards were not for LCA. I wonder why?? JMT

Of course having LEVCON's on the AF version will lower the approach speed. But is it required? I don't think that the Levcons can obviate the drag chute (the levcons will lower the approach speed by about 5-15 knots).
For reasons why ADA did not go for the levcons even on Mk2 is long.
1. Slower speed handling of AF version is not required.
2. The cranked arrow wing of LCA along with the long twist at the wing join gives it similar characteristics to that of a close coupled canard design (albeit not a movable one). I will leave you to learn about that wing design (Hint 1. Do consider the F-16XLs wing. Hint 2: understand how the twist aids in merging the wing and the tail plane. You will love the research.)
3. The CL of the LCA's wing itself keeps rising till 35 degree AoA.
4. The limiting factor is the yaw control authority. The rudder gives good control authority till 24(22?) degrees. But it can be artificially stabilized till about 26 degrees (FOC objective).
5. Therefore adding levcons won't make the plane much more agile. It will definitely allow better slow speed handling.
6. It is very complex non-linear study of how the levcons along with slats could aid in better control. It has been reported in the paper I cited. I am not privy to more information.

vasu raya · Post by **vasu raya** » 28 Jun 2013 21:10

Kartik wrote:it could just be that LSP-8 is still flying without any paint. The new radome could be retrofitted on any of the existing LSP or even PV prototypes, it isn't much of a hassle.

I didn't get what you mentioned in the second para. Just having a chase aircraft doesn't imply that the A2G modes of the MMR-Elta2032 were being tested.

LSP-8 can possibly have new radome and its not insignificant that Jag is used as a chase aircraft. Did the poster say that even the Jag was in yellow primer? possibly a Darin 3 upgrade with a MMR. With Tejas Mk1 and Jaguar having the same MMR, the latter platform becomes a reference not to mention its A2G role.

Approaching IOC-2 the tests they would consider are focused such as testing the new radome for attenuation issues and fixing the known problem with A2G mode of Tejas.