LCA Tejas: News and Discussions

shiv · Post by **shiv** » 23 Aug 2016 06:57

I recall reading that the F-16 always carried wingtip missiles/dummies precisely to reduce up/down bending stress on the wings - that is to say - every flight without missiles would cause the wings to bend upwards much further due to lift generated before returning to normal and this stress was reduced by continuously carrying wingtip loads.

Frankly I will have to check Gokul uncle to see if the latest block F 16s still do that

JayS · Post by **JayS** » 23 Aug 2016 16:46

^^ Shiv, I would believe that very easily. wingtip missiles are suppose to help both structurally as well as aerodynamically. In structural terms, it not only helps in static lift load relieving but also dynamic loads such as flutter are reduced, reduced wing twist ityadi ityadi..

indranilroy wrote: Question. Suppose I want to hang a heavier engine from the same wing, will the wing need strengthening or not? Consider only the weight of the engine.

Short answer -
Yes it will but not by large % as compared to whole wing weight. Since only local strengthening is required. Thus I said, it may not be justified to go for wing redesign.

Long answer-
For a airliner a wing with heavier engine will have more relief at the wing root which is much more significant. Of coarse the heavier engine will demand local strengthening but that would be a small increase in the weight of the wing. For the lifting wing this actually gives more relief. Also since the wing is designed for max manoeuvring load already which is quite huge (3.5 times MTOW for airliner) some increasing in engine weight will not have any affect on the main wing structure. Only locally one has to do some strengthening which will be small fraction of weight of the total wing weight.

Now since for an airliner since the engine is always there it will be taken into account for ultimate load design. Whereas in Fighter since weapons may or may not present the design is done for clean config (Only CCM present, thus they will always carry at least dummy CCMs) which is worst case scenario than with weapons. Of coarse again local strengthening is needed and its more critical here since we are designing for 9G. (Generally pylon load will be taken by one rib which transfers it to the wing spars. The weight is hung by a link to this rib. This local structure will be beefed up).

I hope I am clear enough. I would like to add that this is general case, in most probability this is going to be valid. But specifically for LCA there might be something that I do not know which make this explanation invalid.

SaiK · Post by **SaiK** » 23 Aug 2016 17:19

Lockheed, Wem to set up $318m weapons integration facility for Tejas in India http://www.airforce-technology.com/news ... ia-4986034

I still don't understand these
- what is LM's role?
- weapons integration of what types?
- why do they need 350 acres of land?

Gagan · Post by **Gagan** » 23 Aug 2016 18:38

Who doesn't want a nice big track of land, specially if it comes at a sarkari lease for pennies hain ji?

LM can be a consultant if HAL, MoD agrees and finds it useful, but I don't think that LM will get to manufacture the LCA. Maybe a DDM goof up - LM may have said, they'll supply machinery, processes to help set up a line ityadi

Indranil · Post by **Indranil** » 23 Aug 2016 20:37

I think we are saying the same thing. Aren't we?

JayS wrote: Short answer -
Yes it will but not by large % as compared to whole wing weight. Since only local strengthening is required. Thus I said, it may not be justified to go for wing redesign.

Long answer-
For a airliner a wing with heavier engine will have more relief at the wing root which is much more significant. Of coarse the heavier engine will demand local strengthening but that would be a small increase in the weight of the wing. For the lifting wing this actually gives more relief. Also since the wing is designed for max manoeuvring load already which is quite huge (3.5 times MTOW for airliner) some increasing in engine weight will not have any affect on the main wing structure. Only locally one has to do some strengthening which will be small fraction of weight of the total wing weight.

Now since for an airliner since the engine is always there it will be taken into account for ultimate load design. Whereas in Fighter since weapons may or may not present the design is done for clean config (Only CCM present, thus they will always carry at least dummy CCMs) which is worst case scenario than with weapons. Of coarse again local strengthening is needed and its more critical here since we are designing for 9G. (Generally pylon load will be taken by one rib which transfers it to the wing spars. The weight is hung by a link to this rib. This local structure will be beefed up).

I hope I am clear enough. I would like to add that this is general case, in most probability this is going to be valid. But specifically for LCA there might be something that I do not know which make this explanation invalid.

indranilroy wrote:
JayS wrote:Though one more point to keep in might (not sure how relevant it is in LCA's case) that stores relieve wings from high lift loads and thus actually help wing structure to be less stiff and lighter.
Stiffness: yes. Strength: no. Lighter: I don't think so. If this was so, then hanging more weights from hardpoints would make wings lighter. Why would people not do so? It is a win-win.

I agree with you that the savings from redesigning the wing may not be greater than few 10s of kgs and may not worth be it.

Indranil · Post by **Indranil** » 23 Aug 2016 20:53

Hakim,

There are multiple reasons for always carrying a wingtip pylon. Most important of which is to reduce wing bending moments and hence increase the fatigue life of the upper wing skins, mainspar etc. But there are other reasons too:
1. Decrease turnaround times: Although taking a pylon on or off is easy, one has to run complete checks which increases the turnaround times greatly. Combat turnarounds in 45 minutes are certainly not possible. So they leave them on most of the times. For example if you see pictures of the A-10s they are almost always carrying empty pylons. I read somewhere that this is not the practice with the RAF aircraft. They prefer to save the flight hours of the pylons. To decrease the turnaround times, they keep the pylons attached to the load (say wing tank), saving on one set of tests.
2. Wingtip pylons help reduce wingtip vortices, thereby decreasing induced drag. They do increase profile drag, primarily through interference drag. This however is generally less than the reduction in induced drag.
3. They increase roll-inertia adding stability. Remember the modifications suggested for IJT. On the Cessna-twins, the wingtip tanks were called "stabila-tip tanks".

JayS · Post by **JayS** » 23 Aug 2016 21:11

Just wanted to highlight, hanging weight blow wing will make the wing lighter overall. But for Fighters the weapons load is not considered for ultimate strength design point (Only for local structure it will matter). For airliners I am sure they do consider engine weight and it does help reduce wing weight. (I discussed this with my colleague who is structural engg and he agrees with this too. But I will ask another one who has worked on wing structures in past).

PS: From wiki page: https://en.wikipedia.org/wiki/Podded_engine

Placing engines on the wing provides beneficial wing bending relief in flight. The further the engines are away from the fuselage the greater the wing bending relief so engines buried in the wing root provide little relief. Almost all modern large jet airplanes use engines in pods located a significant distance from the wing root for substantial wing bending relief. The pods are in front of the wing to help avoid flutter of the wing which, in turn, allows a much lighter wing structure.

geeth · Post by **geeth** » 23 Aug 2016 23:15

Whathappens to the wing loading when ALL the weight of the fuel and the engines and tons of ice in winter which all act downwards with ZERO lift just before take off?

Let us move on..enough of over simplification about aircraft design.

rahulm · Post by **rahulm** » 24 Aug 2016 07:11

PART 4

RADAR: There isn't much faith that LRDE will deliver. LRDE Is coy and secretive and not very engaging. Their POV is: give us your specs and wait. There is no progress reporting and dialogue. Both the organisation and the radar are a black box.

When I mentioned UTTAM, I got blank looks - they had never heard that name. When I mentioned the Israeli India radar JV I got the same blank and don't care looks. I spent some time talking up LRDE's radar achievements and explaining that miniaturising is a non trivial task. There was some sympathy but no appetite. I think a more transparent engagement model will go some way In establishing trust.

In contrast, the end user and HAL camaraderie appears to be good.

The end user is happy with the Israeli kit installed. The 2032 is well liked and familiar. The Derby and Python integrate well. They are looking forward to having the 2052.

The sense I got, and I could be wrong, was there isn't much knowledge about and enthusiasm for the LRDE radar. I feel, it might be a long journey before we see Tejas with a desi radar.If LRDE have cracked the radar nut they certainly are keeping it hush hush. Maybe, LRDE skunk works might surprise.

The Cobham Quartz radome has been installed on 2 aircraft and the performance compared to the desi radome with the 2032 is appreciable - and I am being polite here. I don't want to get specific on this topic but the desi radome needs more work.

The desi radome design is quite different from contemporary western and Russian designs. Are there any public domain pic of the desi radome internals?

JayS · Post by **JayS** » 24 Aug 2016 09:06

^^Great to know the improvement due to new radome is "Appreciable". The communication gap between desi orgs is alarming though.

disha · Post by **disha** » 24 Aug 2016 10:45

^^ RahulM'ji - by denying knowledge one can stave off leaks too. Is it possible that is the case for LRDE.

PratikDas · Post by **PratikDas** » 24 Aug 2016 12:26

So it seems that Tejas' cataract has been removed and a new Cobham lens is giving 20/20 vision. Great news.

JayS · Post by **JayS** » 24 Aug 2016 12:30

^^ Possible but clearly the lack of communication is making people indifferent towards LDRE. That's not a good sign. You don't need to tell sensitive data always to keep people in the loop, I believe. Timely updates sanitized from any sensitive info can definitely be shared with ADA/HAL/IAF.

Dileep · Post by **Dileep** » 24 Aug 2016 12:46

With DRDO units, if you hear nothing, then nothing is there to hear.

sanjayc · Post by **sanjayc** » 24 Aug 2016 19:27

Tejas grounded in Bhopal, AAI officials remain mum
http://www.hindustantimes.com/bhopal/te ... XRlrO.html

vnms · Post by **vnms** » 25 Aug 2016 00:20

Going out on a limb here and assuming that the cockpit door was jammed in open position.

ranjan.rao · Post by **ranjan.rao** » 25 Aug 2016 04:31

^^why is grounded used here Has it been disqualified to fly further until notice..and what do they expect AAI officials to tell them about it, DCNS style detailed info. and yes it has to have a reference to the "unparalleled pride and happiness for Modi"

shiv · Post by **shiv** » 25 Aug 2016 07:48

Folks, I hate to use the term but I will use it anyway. "Please introspect" is what i want to say.

half the time on this forum we know and curse print and electronic media for reporting absolute bullshit. the other half we get our chaddis in a twist because we believe reports from those same media.

That LCA report is from some guy standing outside the tarmac and speculating. What we do on BRF is the same thing that reporters do, except that we don't publish as a news medium.

I tend to disbelieve all media reports initially. Any given report could be true or could be false. Never take any report at face value. Media are under pressure to make money by attracting attention, which is what prostitutes also must do to survive

pushkar.bhat · Post by **pushkar.bhat** » 25 Aug 2016 10:08

sanjayc wrote:Tejas grounded in Bhopal, AAI officials remain mum
http://www.hindustantimes.com/bhopal/te ... XRlrO.html

This looks like a case of sour grapes reporting. Perhaps Shri Mujeeb Faruqui, Hindustan Times, Bhopal wanted a dekho at the LCA but was blocked so he filed a grounded report.

navneeet · Post by **navneeet** » 25 Aug 2016 10:48

link from a vernacular paper. It seems the pilot is a Bhopali, and would take off after a night halt

http://epaper.bhaskar.com/detail/?id=10 ... view=image

navneeet · Post by **navneeet** » 25 Aug 2016 10:53

Following up the story.. due to some technical problem take off postponed.

http://epaper.rajexpress.in/Details.asp ... d=67791024

sanjayc · Post by **sanjayc** » 25 Aug 2016 11:03

Translation ^^^

Tejas suffered a tecnical fault in Bhopal during take off and couldn't depart for Bangalore.

The aircraft returned from the runway back to the airport. It had arrived in Bhopal on Tuesday and had to leave same afternoon to Bangalore. However, due to inclement weather, it was not give permission to fly by the ATC. It was thereafter decided that the plane will leave the next day.

On Wed, when it began running on the runway, its engine developed a fault. It was immedaiately brought to the old airport and a team of engineers from airforce was called. The engineers said the fault could be recitifed only by late night. The plane will now take off for Bangalore on Thu morning.

Will · Post by **Will** » 25 Aug 2016 11:46

Even if it developed a fault whats the big deal? Its a machine and can develop a fault. Super duper foreign maal dont develop faults? What was the availability of the su-30 again?

Kashi · Post by **Kashi** » 25 Aug 2016 12:21

Will wrote:Even if it developed a fault whats the big deal? Its a machine and can develop a fault. Super duper foreign maal dont develop faults? What was the availability of the su-30 again?

It was an engine fault, the most foreighn of all the foreighn maal in Tejas.

JayS · Post by **JayS** » 25 Aug 2016 12:45

pushkar.bhat wrote:
sanjayc wrote:Tejas grounded in Bhopal, AAI officials remain mum
http://www.hindustantimes.com/bhopal/te ... XRlrO.html
This looks like a case of sour grapes reporting. Perhaps Shri Mujeeb Faruqui, Hindustan Times, Bhopal wanted a dekho at the LCA but was blocked so he filed a grounded report.

Looks like that's the case

Read this para from the farticle:

Photographers were not allowed to enter the airport to click photos of the LCA, which was a matter of “unparalleled pride and happiness” for Prime Minister Narendra Modi’s on the day of its induction.

Note how NaMo was brought in for no damn reason.

deejay · Post by **deejay** » 25 Aug 2016 13:45

Kashi wrote:
Will wrote:Even if it developed a fault whats the big deal? Its a machine and can develop a fault. Super duper foreign maal dont develop faults? What was the availability of the su-30 again?
It was an engine fault, the most foreighn of all the foreighn maal in Tejas.

Sirs, these are regular events. Journo got what he wanted. No problems with Tejas. Please can we drop this nonsensical report.

Indranil · Post by **Indranil** » 25 Aug 2016 20:47

Deejay,

Have you seen the HTT40 or IJT flying regularly off late. Any more sightings of Saras. Please reply in the Indian military aviation thread. Thanks.

Khalsa · Post by **Khalsa** » 26 Aug 2016 01:51

Seriously are we going to report every time the mechanic spills 10 ml of Oil on the tarmac or on the body of a/c
WTH is going on in with press reporting

Wait I know the answer... we are moving from a world of deep, well articulated articles to click baits.

Dileep · Post by **Dileep** » 26 Aug 2016 06:50

The final qualification flight of the radome was yesterday. Full range and some more to spare!! The old one was HALF range onlee.

Another data point is, one of the problems faced with the refueling pod is, its potentially putting its shadow into the radar beam. No further information sought/made available.

Sid · Post by **Sid** » 26 Aug 2016 08:56

Dileep wrote:The final qualification flight of the radome was yesterday. Full range and some more to spare!! The old one was HALF range onlee.

Another data point is, one of the problems faced with the refueling pod is, its potentially putting its shadow into the radar beam. No further information sought/made available.

Excellent news. But it's a surprise to know desi radome was lacking by 50%, but I hope they will use it as a learning.

sum · Post by **sum** » 26 Aug 2016 09:45

^^ Was this our first attempt at a radome?

tsarkar · Post by **tsarkar** » 26 Aug 2016 13:22

sum wrote:^^ Was this our first attempt at a radome?

NAL has supposedly developed the Sea Harrier & Jaguar IM radomes for same Elta 2032 radar that successfully cued Harpoon(s) during a recent test. Though given the small numbers of both fighters, the radomes could've been built in the labs.

Dileep wrote:one of the problems faced with the refueling pod is, its potentially putting its shadow into the radar beam.

I guess you meant probe.

The position is odd, if the Jaguar was the final configuration, and in a limited estate aircraft like Tejas, fitting the plumbing and radar LRUs would be a tight affair.

Mockups and initial setups were more conventional

Wonder what caused moving it from the conventional position to the nose position.

Whatever the case, lots of CFD analysis and test flights would be required.

rohitvats · Post by **rohitvats** » 26 Aug 2016 13:28

Dileep wrote:The final qualification flight of the radome was yesterday. Full range and some more to spare!! The old one was HALF range onlee. Another data point is, one of the problems faced with the refueling pod is, its potentially putting its shadow into the radar beam. No further information sought/made available.

Thank you, and rahulm, on these data points.

These snippets of information about radome and radar are a lesson for BRFites. I remember there was much chest-beating and R&D when the news about radome surfaced. Every one went hammer and tongs at IAF for playing truant and downplaying the significance of the issue. It was claimed to be another example of uncooperative IAF stymieing induction of a domestic product.

Same case with radar - if you believe SM chatter by usual suspects, it would seen that Uttam is just around the corner.

It is important that we don't jump the gun on issues till we know the complete picture. At least don't start name calling the IAF when full facts are not known.

Dileep · Post by **Dileep** » 26 Aug 2016 16:22

Some more "speculations":

1. Aero India 17 is likely have the trainer giving rides to people who matter. SPs will fly demos.
2. The customary static display plane may allow some important visitors to sit in it. (I sincerely hope I could convince them that I am indeed worthy of that treat

)
3. The Mark-2 Avionics suite would give goosebumps to jingoes. I hope the full details finds a place on the infoboard at AI-17. A demo setup of the Mark-2 Glass cockpit is highly likely be there.

sum · Post by **sum** » 26 Aug 2016 16:30

These snippets of information about radome and radar are a lesson for BRFites. I remember there was much chest-beating and R&D when the news about radome surfaced. Every one went hammer and tongs at IAF for playing truant and downplaying the significance of the issue. It was claimed to be another example of uncooperative IAF stymieing induction of a domestic product.

As always, i guess the truth is in between.

If we just go by BRF, DRDO is the cutting edge pioneer delivering world beating products one after the other whereas if i talk to few services folks ( even "desi friendly" IN folks), the kind of stories about few of the products ( claimed as succesfully inducted) are hair-raising and sad to hear.

So, its a grey area and neither black or white, IMHO

shiv · Post by **shiv** » 26 Aug 2016 16:55

rohitvats wrote:
It is important that we don't jump the gun on issues till we know the complete picture. At least don't start name calling the IAF when full facts are not known.

What! I am reporting you to admins for trying to close down BRF

JayS · Post by **JayS** » 26 Aug 2016 17:35

^^

What will jingos on BRF do until the picture gets cleared?? That takes many years sometimes. BR was down 2 months and it was painful just at that..

Karan M · Post by **Karan M** » 26 Aug 2016 19:12

rohitvats wrote:
Dileep wrote:The final qualification flight of the radome was yesterday. Full range and some more to spare!! The old one was HALF range onlee. Another data point is, one of the problems faced with the refueling pod is, its potentially putting its shadow into the radar beam. No further information sought/made available.
Thank you, and rahulm, on these data points.

These snippets of information about radome and radar are a lesson for BRFites. I remember there was much chest-beating and R&D when the news about radome surfaced. Every one went hammer and tongs at IAF for playing truant and downplaying the significance of the issue. It was claimed to be another example of uncooperative IAF stymieing induction of a domestic product.

Same case with radar - if you believe SM chatter by usual suspects, it would seen that Uttam is just around the corner.

It is important that we don't jump the gun on issues till we know the complete picture. At least don't start name calling the IAF when full facts are not known.

Uttam status is detailed in DRDO Annual Report in specifics.
So we don't need to jump the gun or otherwise, based on SM chatter. Annual Report/s, Partner vendor reports (eg Astra above) do have details.

https://blog.mygov.in/ebooks/drdo/DRDO_ ... ml#page/50

In specific, a prototype test unit is in trials & has been equipped with A2A modes. This is pretty much the same approach as taken on the AEW&C test program. The next step will be to have a fully populated array & then the ground test bed will be used to fully debug the radar & derisk it to the extant possible, then a flying test bed will follow. Either on the DO228 they got approval for or one of the LCA prototypes.

Previously, the MOD Annual Report also carried a report on Uttam & its progress.

But at the very least, I would estimate (FWIW), that a fully engineered variant of Uttam on a FTB to a decent level of maturity is at least 5 years away. Then operational trials will take at least another 3-4 years.

The Russians, delivered a Bars Mk1 in 2001 - it took till 2014 IIRC for them to finally meet IAF specifications!!

Of course we are not starting from scratch this time around, with the AEW&C program being a very useful technology generator, but still, we are several years away (IMHO) from fielding operational AESAs for fighters.

However, given the sheer disaster that is the TOT driven procurement process, and the shenanigans of some of the vendors who renege on their deals, I would not be surprised if Uttam ends up becoming the real choice even for the LCA Mk1A. QRSAM & Maitri come to mind.

I hope that does not turn out to be the case, and the EL/M-2052 or whatever in-between AESA is chosen does come to be acquired.

Uttam can always be developed further for the AMCA - or variants developed for other IAF fighters.

Karan M · Post by **Karan M** » 26 Aug 2016 19:22

sum wrote:
These snippets of information about radome and radar are a lesson for BRFites. I remember there was much chest-beating and R&D when the news about radome surfaced. Every one went hammer and tongs at IAF for playing truant and downplaying the significance of the issue. It was claimed to be another example of uncooperative IAF stymieing induction of a domestic product.
As always, i guess the truth is in between.

If we just go by BRF, DRDO is the cutting edge pioneer delivering world beating products one after the other whereas if i talk to few services folks ( even "desi friendly" IN folks), the kind of stories about few of the products ( claimed as succesfully inducted) are hair-raising and sad to hear.

So, its a grey area and neither black or white, IMHO

Almost all "inducted" equipment - whether domestic or foreign, needs a period of service, before its debugged and consistently shown to be soldier (aka operational environment proof).

The sad fact is that while some folks especially in the media, constantly complain & whine about domestic programs worrying whether they ever came good and then reinforce a perception about the local items even in users who become wary, the reality is that its our expensive "proven" imports which often languish for want of spares & operational effectiveness is zilch! The much touted Israelis, French - never mind the Russians - have all delivered duds after duds, only to be rewarded with more follow on orders.

The basic issue is that when we go back to have the vendor fix these duds - whether they be missiles for the AF or the Army's MBRLs or tanks or RAWS super secret gizmos - the vendor laughs, points to the fine print, asks for more money to fix those issues and the items languish in sheds or storage. While BRF talks up these capabilities and the fact these imports had to be somehow made because domestic capabilities were not "mature" or overpromised.

In contrast, most of the Indian programs which were initially acclaimed to be "duds" end up being patiently fixed and then deliver.
One of the sonars for instance, berated for holding up the IN's modernization, ended up allowing the IN to outperform a western "leader" in exercises.

The Indra radars in their first batch had performance, serviceability issues. A decade and a half thence we have many of our own radars in production, deployment which are clearing service trials.

The intent should be to focus on the long term & keep at it. Not flashes in the pan and rushing for imports which end up being operationally compromised (Scorpene saga), complete procurement disasters (Gorshkov, T-90, MiG-29K) or otherwise.

The number of imports which have "delivered" can literally be counted on one hand.. as systems get more complex, imported units also warrant a harder look as to whether they have actually performed beyond the brochures!

Which is not to say DRDO has cleared all the hurdles and everything is hunky dory. There are still glaring areas where we need to establish a proven consistent capability of inducted, performing, proven systems.

There are a list of programs mentioned here & we need to appreciate both the positives and the challenges ahead.
https://blog.mygov.in/ebooks/drdo/DRDO_ ... Report.htm
For instance, huge progress in making our own EO systems and integrated TI type systems. However, we currently don't have a fab for the crucial heart of the device, the IR matrix, so we remain dependent on that from the French and the Israelis..We are lagging in UAVs, in propulsion, in some key areas where multiple programs have yet to make their mark. But persistence is key.

NSTL took ages to deliver its torpedo & countermeasure programs but they have finally cleared IN trials. In short, persistence, & long term involvement from the services and clear support, funding from the Govt does pay off.

The issue then is not of service orders, but plain and simple, technological and infrastructural challenges which are yet to be overcome. Service interaction, while not ideal across all programs has definitely picked up.

On the plus side, we are not paying through our nose for the integrated unit. So it goes...

Karan M · Post by **Karan M** » 26 Aug 2016 19:28

sum wrote:^^ Was this our first attempt at a radome?

In a nutshell, yes.
The radome was from DRDL & an older design, made per the original MMR specs, even prior to the Israelis stepping in. The program was likely given to them because the NAL effort to make radomes had not started by then (they went on to make the radomes for EL/M-2032 and ESM programs with a dedicated lab/LSP production capability). NAL has moved onto FSS programs & other advanced radomes are in development. DRDL itself has moved onto newer radome designs for the missile programs (all the seeker equipped missiles have radomes). The Cobham order was clearly given to minimize further delay in the Tejas program by developing a new radome, but the capability/experience now exists to take up such projects in the future.