LCA: News & Discussions - October 2016

Bala Vignesh · Post by **Bala Vignesh** » 07 Apr 2017 19:50

JayS wrote:
One option was, (which I have advocated previously and I rather like it) is to induct MK1 in A2A + limited A2G role and quickly move on to MK2 with full multirole capabilities.

This ideally would have been the way to go for the LCA!!!
It's been quite a learning session for me the last couple of weeks in this thread. There was always something new to learn!!!
Many thanks to all the contributors.

ramana · Post by **ramana** » 07 Apr 2017 20:10

Karan M wrote:btw, the fa-18 issue? minor problem of hypoxia only. f-22 also had it.

no problem. don't fly as much. or high. or this or that...

meanwhile our "desi products" are in news for "3-legged cheetah" while of course, these imports get fawning editorials in all the press and from rtd bigwigs talking about how they are "essential for superiority" vs TSPAF or PRC or whatever.

The US knows it has to fix those issues.
However in India the bigwigs can fart all they want about desi products and keep quiet about flaws in imports.

JayS., One factor we need to consider is the MoD and MoF * which are tardy in asking and releasing the funds. This causes the schedule crunch. Hence accelerated testing happens as they are still needed for achieving milestones.

* MoD delays in asking for funds and argues with the services and DRDO if those are needed. And then MoF claims budget priorities and allocates late and often less than asked for.
Reason is these worthies think the great white hope will swoop down and save India if push comes to shove.

ramana · Post by **ramana** » 07 Apr 2017 20:17

Just for my ignorance, how much does the Astra weigh?

Thanks, ramana

JayS · Post by **JayS** » 07 Apr 2017 20:21

ramana wrote:
Karan M wrote:btw, the fa-18 issue? minor problem of hypoxia only. f-22 also had it.

no problem. don't fly as much. or high. or this or that...

meanwhile our "desi products" are in news for "3-legged cheetah" while of course, these imports get fawning editorials in all the press and from rtd bigwigs talking about how they are "essential for superiority" vs TSPAF or PRC or whatever.

The US knows it has to fix those issues.
However in India the bigwigs can fart all they want about desi products and keep quiet about flaws in imports.

JayS., One factor we need to consider is the MoD and MoF * which are tardy in asking and releasing the funds. This causes the schedule crunch. Hence accelerated testing happens as they are still needed for achieving milestones.

* MoD delays in asking for funds and argues with the services and DRDO if those are needed. And then MoF claims budget priorities and allocates late and often less than asked for.
Reason is these worthies think the great white hope will swoop down and save India if push comes to shove.

Saar, we can reason somewhat with DRDO and IAF, but MoD is beyond that. No point in even discussing.

Imagine if MP was RM in 2001. Though JF was very supportive, I doubt he could have reconciled the two side like what MP achieved in 2015.

Zynda · Post by **Zynda** » 07 Apr 2017 20:29

ramana wrote:Just for my ignorance, how much does the Astra weigh?

Thanks, ramana

~155 Kg

ramana · Post by **ramana** » 07 Apr 2017 21:16

Good. Most likely Astra will get CCM role once its qualified.
Then don't want rhona/dhona about can't fit on LCA outer pylons.

Zynda · Post by **Zynda** » 07 Apr 2017 21:26

Ramana, per the poster from AI which was posted earlier in this thread, Astra can be used both for CCM as well as BVR engagements. But per tsarkar, the current weight qualification of LCA's outboard pylons are 150 Kg onlee.

Cain Marko · Post by **Cain Marko** » 07 Apr 2017 21:59

Karan M wrote:Comrade! We hab solution!

Future proof Arjun/future proof LCA. You decide.

We must trash all domestic products and buy this since it is Russian made, at once.

ramana · Post by **ramana** » 07 Apr 2017 22:22

Zynda, The IIR seeker version of Astra might not weigh 155 kg.

sankum · Post by **sankum** » 07 Apr 2017 23:21

Armed forces lost 48 aircraft, 21 choppers since 2011

Defence Minister Arun Jaitley, replying to another query, said the ADA is also developing MK-II version of LCA for the Navy with a higher thrust engine than the one used in MK-I version of Tejas.

“Final Operational Clearence (FOC) of LCA (Navy) MK II is likely to be obtained by 2023 for induction in Indian Navy and FoC for Air Force MKII is likely to be obtained by December 2025,” he said.

Cybaru · Post by **Cybaru** » 07 Apr 2017 23:53

sankum wrote:
Defence Minister Arun Jaitley, replying to another query, said the ADA is also developing MK-II version of LCA for the Navy with a higher thrust engine than the one used in MK-I version of Tejas.

“Final Operational Clearence (FOC) of LCA (Navy) MK II is likely to be obtained by 2023 for induction in Indian Navy and FoC for Air Force MKII is likely to be obtained by December 2025,” he said.

FOC a full year before the Mythical GripenNG! Nice!

brar_w · Post by **brar_w** » 08 Apr 2017 00:04

Cybaru wrote:
sankum wrote:
FOC a full year before the Mythical GripenNG! Nice!

That would be Planned FOC a year before Planned FOC..given the way most aerospace programs have been going of late around the world...

Cybaru · Post by **Cybaru** » 08 Apr 2017 00:19

brar_w wrote:
Cybaru wrote:
FOC a full year before the Mythical GripenNG! Nice!
That would be Planned FOC a year before Planned FOC..given the way most aerospace programs have been going of late around the world...

Yes, I noticed! Just wanted to highlight it nonetheless.

srai · Post by **srai** » 08 Apr 2017 06:11

Zynda wrote:Ramana, per the poster from AI which was posted earlier in this thread, Astra can be used both for CCM as well as BVR engagements. But per tsarkar, the current weight qualification of LCA's outboard pylons are 150 Kg onlee.

These new studies show the outboard pylon rating may be around 250kg.

shiv · Post by **shiv** » 08 Apr 2017 07:11

Let me ask a question based on two diametrically opposite statements made by various people:
1. Tejas outboard pylon was stressed only to 45 kg (or 60 kg?)
2. Tejas Navy undercarriage was over-engineered and can do with weight reduction in future iterations.

Now for years I have heard people tell me how marvellous modern computer modelling is and how very accurate estimates of load bearing ability can be arrived at by some mouse clicks and smart engineers. I know that and that is not the answer I am looking for, but I need to word my question carefully.

An outboard pylon that was designed for 45 (or 60) kg might possibly be able to take a greater load. I guess that "load" would mean both static loads where increasing weights are slung off that hardpoint till the something breaks - which is relatively easy. But dynamic loads as experienced in flight would ultimately have to be proven over a longer period of time - presumably by simulating wing stresses with increasing loads and testing for fatigue damage. To me - what this means is that when a hardpoint is "proven" to be able to withstand a 45 (or 60) kg load it does not mean that it cannot take anything higher. Unless it has been tested and proven that it breaks at 75 kg or that fatigue life becomes intolerably low at that higher load the designers/testers may not know the absolute maximum load that it can safely take.

Does anyone have any information about whether the LCA wing has been tested to breaking with heavier and heavier loads on the outboard pylon? Is there any information (article/video) where someone states that the outboard pylon can (for example) take a maximum of say 80 kg onleee and then phuttt!?

We know for a fact that the no one in ADA knew at exactly what load the undercarriage of the LCA Navy would go phutt. We only know that they realized that it was overdesigned. What information do we have that the outboard pylon was not overdesigned but instead honed to such great and accurate perfection that it would snap at loads greater than 45 (or 60?) kg?

In fact all these pretty pictures of outboard pylon carrying something in excess of 150 kg - or at least an R-73 indicate that the pylon can probably carry more. What evidence do we have in the form of statements, articles or videos that the weight carrying capacity of that pylon was "increased" by suitable strengthening as opposed to simply proving that it was over engineered in the first place and can actually carry more?

I put it to folks that without such information it would be unfair and inaccurate to respectively read the minds and intentions of past ADA designers/engineers.

I would like to know if anyone has come across any specific information related to these questions and preferably not general engineering books/college gyan handed down sneeringly by people with good teeth to non engineers.

Neshant · Post by **Neshant** » 08 Apr 2017 08:05

One thing i am sure of is the LCA will not crash anywhere near as frequently as aircraft designed by countries with Northern climates.

geeth · Post by **geeth** » 08 Apr 2017 08:30

I would like to know if anyone has come across any specific information related to these questions and preferably not general engineering books/college gyan handed down sneeringly by people with good teeth to non engineers.

That is what I was also trying to say. The wing is not a rigid structure. In fact it is quite flexible for the loading (both static and dynamic) it undergoes during a flight. There will be issues emerging in each flight regime which even the best designers would not be able to predict even with best computing power. Abd ADA engineers are novices so they are extra cautious..thats all. They are not sure hence cautious. If we had a few hot headed mavericks heading the design team, LCA would have crashed and project wound up long back. They have reached this far by reading books and observing others and occasional help from experts where available. Isnt it great?

For all you know, it may be possile to sling a 500 kg bomb at wing tip and fly. How many times and what speed and what damage to aircraft is the question.

This is a machine which has to fly for decades with a human being, overcome all adversaries and return to base safely everytime and remain as good as a new one.

It is not rocket science...something much more than that. If people dont realise it, you will continue to get boring posts vomiting undergrad gyan. That is also necessary,but repetition kills the dynamic interest.

Gyan · Post by **Gyan** » 08 Apr 2017 08:57

ramana wrote:Zynda, The IIR seeker version of Astra might not weigh 155 kg.

There is no indication yet of IIR aversion. The target weight of Astra was 155kg but it can be slightly heavier due to so many iterations & changes. So anything between 150-180kg.

ramana · Post by **ramana** » 08 Apr 2017 08:59

Shiv The ADA will gradually find out the limits of the LCA. So far they have calculated stresses and flight loads induced strains. Design margins will be 1.5 as pilot is involved.

shiv · Post by **shiv** » 08 Apr 2017 09:35

ramana wrote:Shiv The ADA will gradually find out the limits of the LCA. So far they have calculated stresses and flight loads induced strains. Design margins will be 1.5 as pilot is involved.

Sure ramana - and at the risk of belabouring the point let me do a hypothetical "backwards guesswork" on what might have been one ADA thought process.

In 1983 (or whenever the spec was frozen) they wanted X kilos total on inboard pylons - for dumb bombs etc. What did they want for outboard pylons? The only spec they had was ~50 kg for R-60. So they went ahead and designed a wing that would take a total load of all the pylons - i.e several thousand kg for inboard pylons and ~50 kg for outboard. Then they would have tested each of these for loads individually and collectively. They would certainly have proven the ability of the outboard pylon to carry 50 Kg + 50% extra safety margin. That is why they stated that it was ready to take the R-60.

But did they stop there because the design specs (of 50 kg+ 50% margin) were met or did they go ahead and test to destruction and did that testing to destruction prove that ~50 kg (+50% margin) was the absolute limit of the outboard pylon? In fact further testing may have shown that those outboard pylons can actually hold much higher loads up to 150 kg static and dynamic plus margins. We just don't have information to either confirm or deny that. Without such information everything is speculation. General gyan like "engineers will do this and software will do that" is pointless in this instance

shiv · Post by **shiv** » 08 Apr 2017 10:25

geeth wrote: For all you know, it may be possile to sling a 500 kg bomb at wing tip and fly. How many times and what speed and what damage to aircraft is the question.

Exactly. The 45 kg limit was never stated as being the absolute, final wing breaking limit. It was only equal to a design requirement. There may be design redundancy for higher loads that can be stated only after testing. That testing will be done only if it is necessary to prove a higher load. I think that is what has been done. Sitting here today and saying that 45 kg is the absolute limit for the outboard pylon may not necessarily be right.

JayS · Post by **JayS** » 08 Apr 2017 10:50

Well, I thought wing redesign due to increased pylon load on outboard pylon and the delay hence is a fact and accepted by all. Maybe Vina can provide the link to the old discussions if those posts are available still..? I dont remember those discussions perhaps because its before I started lurking here.

And so far I have not seen any report on STS testing for LCA. Its a pending work. Was planned for 2012 but didnt happen then.

Well that reminds me that one poster here posted chaiwalla info that fatigue life for gun integration (gun mounting structure perhaps) is already done and proven for LCA.

Zynda · Post by **Zynda** » 08 Apr 2017 12:05

JayS wrote: And so far I have not seen any report on STS testing for LCA. Its a pending work. Was planned for 2012 but didnt happen then.

What does STS mean?

Marten · Post by **Marten** » 08 Apr 2017 12:31

Structural test specimen.

srai · Post by **srai** » 08 Apr 2017 12:37

ramana wrote:Shiv The ADA will gradually find out the limits of the LCA. So far they have calculated stresses and flight loads induced strains. Design margins will be 1.5 as pilot is involved.

1.5 x breaking point is ideal as stated by the PM working on the HTT-40. But Indian designers, being inexperienced, have tended to be more cautious with their designs and over-engineer for safety. Closer to 2 x breaking point is more common. These things are proven with a static stress specimen. LCA has had a stress airframe and testing that for a long time now. Look at any LCA brochure and you will see it.

Other thing to point out is that even if an airframe/wing can carry more weight, the heavier loads, more Gs and speed will stress the airframe and engines more than normal usage. Things won't last as long.

shiv · Post by **shiv** » 08 Apr 2017 12:48

As long as the wingtip/outboard section of the wing can bear a heavier load it should be possible to keep the total stress on the wing roots within design limits by reducing the load carried on the inner pylons no?

srai · Post by **srai** » 08 Apr 2017 12:49

Marten wrote:Structural test specimen.

srai · Post by **srai** » 08 Apr 2017 13:36

Boeing-777 Wing being tested to breaking point. Breaks at 154%.

shiv · Post by **shiv** » 08 Apr 2017 14:42

Structural testing of HF 24 Marut

shiv · Post by **shiv** » 08 Apr 2017 20:29

srai wrote:These things are proven with a static stress specimen. LCA has had a stress airframe and testing that for a long time now. Look at any LCA brochure and you will see it.

Watch about 2 minutes from the point linked below. Two scenes even show an R-60 mounted on a LCA wing and being put through tests. I am sure the same tests were later repeated with the R-73 or whatever and I am guessing the wings stood up well. My guess that is
https://youtu.be/755G4aqQ9mk?t=406

srai · Post by **srai** » 08 Apr 2017 21:41

^^^
Good videos. Hadn't seen it in a while.

JayS · Post by **JayS** » 08 Apr 2017 21:53

shiv wrote:
srai wrote:These things are proven with a static stress specimen. LCA has had a stress airframe and testing that for a long time now. Look at any LCA brochure and you will see it.
Watch about 2 minutes from the point linked below. Two scenes even show an R-60 mounted on a LCA wing and being put through tests. I am sure the same tests were later repeated with the R-73 or whatever and I am guessing the wings stood up well. My guess that is
https://youtu.be/755G4aqQ9mk?t=406

FYI, the particular test they showed with R60 on is called Structural Coupling Test (The narrator mentions it in the list of test facilities he spell out). Its done to find out the frequency response of various airframe components so that those frequencies can be eliminated from the FCS's response using filters (basically FCS will ignore those vibratory motions) to avoid resonance or any other such issues.

Here is a paper from LCA team which nicely describes this.

nal-ir.nal.res.in/5026/1/INCAST_2008-117.pdf

It seems there are three main structural tests for LCA involving entire Airframe:
- MAST (Main Airframe Static Test)
- MAFT (Main Airframe Fatigue Test)
- SCT (Structural Coupling Test)

From this video we see that they have done SCT on the TD airframe in early 2000s for sure, and may be MAST/MAFT too. And from Broadsword blog, it is clear that these tests are repeated on early LSP series (Picture posted by srai above). Its not too much of a stretch of imagination to think that these must have been again repeated with late LSPs which are very close to production standard.

They must have done Design load tests but I highly doubt the Ultimate load test is done so far. I think its still pending.

PS: http://ajaishukla.blogspot.in/2008/03/h ... -test.html

Karan M · Post by **Karan M** » 09 Apr 2017 03:40

Is it 115km?

JayS wrote:
Karan M wrote:Rough estimate, 660 odd TRMs, each of around 7.9W peak power.
For reference: my post from October 2015
viewtopic.php?p=1922326#p1922326
Some infor on Uttam from my side. My knowledge of avionics is limited so asked only some simple questions. I was having general chat with a young lady there who works on the SW side and with a more senior guy for few minutes. Expressed my gratitude for working for the nation's progress.

- It has ~700 TR modules
- Expected range 150km for 2m2 target size.
- Weight of entire package is 110kg.
- GaAs based. No GaN so far. Earlier GaAs was procured from US, but they sanctioned it few years ago (may be 4yr ago?) After that, now we make GaAs TRMs in India.
- They have 3 prototypes so far and by end of the year it would be 6. some more might be built.
- All SW coding is done - all modes are covered - A2A, A2G, SAR etc. What's remaining is putting it on a Fighter and test/debug. But LDRE seemed very confident that they can fully qualify Uttam on LCA within 2yrs.
- Extensive ground testing done. They had done a Tech Demo project in the past where they built small AESA radar and flight tested it on helicopter. THey have run through entire dev cycle on that TD. That's what gives them confidence on Uttam now, they told me.
- Right now it can search for up to 100 targets, track 20 and target 1 at a time. There is no particular limitation to increase number for simultaneous targeting as they have ample reserve processing power. Right now its kept at 1 for the ease of testing/debugging.
- Cooling requirement is of 3.6kW. IIRC, LCA has heat exchanger qualified for 3.5kW already (IR may remember better, its from one of the tenders). So Uttam may need some minor changes on that front.
- A lot of experience from Netra AWACS is helping the Uttam project.

I have some pictures, one with a close up view of individual TR module. I am not sure if its OK to put that one on internet. I took similar pic for Rafale Radar as well. But I will put other pics soon. Not getting time to process the pics. Need to compress them for uploading somewhere.

srai · Post by **srai** » 09 Apr 2017 05:13

I have some pictures, one with a close up view of individual TR module. I am not sure if its OK to put that one on internet. I took similar pic for Rafale Radar as well. But I will put other pics soon. Not getting time to process the pics. Need to compress them for uploading somewhere.

BR upload page:
http://www.bharat-rakshak.com/media/main.php

JayS · Post by **JayS** » 09 Apr 2017 07:27

Karan M wrote:Is it 115km?

I didnt know before going to AI that Uttam specs say 115km. So i didnt ask for clarification. But I might have misheard "one fifteen" as "one fifty". However I did get it clarified it was for 2m2.

shiv · Post by **shiv** » 09 Apr 2017 07:42

JayS wrote: They must have done Design load tests but I highly doubt the Ultimate load test is done so far. I think its still pending.

It follows from this statement that accusing designers of lack of foresight and not planning for the future because the outboard pylon was qualified only for the R-60 at the outset is a conclusion that is both inaccurate and unfair. At best we lack the information to reach any such conclusion.

srai · Post by **srai** » 09 Apr 2017 07:51

^^^
For certification, 150% test is required. Things shouldn't break before that. How much more beyond that 150% things break at could be a continuing exercise. Useful for airframe optimization and weight reduction.

It's not a trivial exercise integrating new weapons. Lots of studies need to be performed in the airframe side of things using CAD, CFD, wind tunnel, separation studies, structural load and vibration testing. Given how much goes into integration, not at all difficult to see issues showing up and needing to rectified. Just another day in an engineer's work

shiv · Post by **shiv** » 09 Apr 2017 08:09

srai wrote:^^^
For certification, 150% test is required. Things shouldn't break before that. How much more beyond that 150% things break at could be a continuing exercise. Useful for airframe optimization and weight reduction.

The meaning of this statement is that If R-60 weighs 60 kg and the wing can withstand 90 kg - it will be qualified for R-60. That does not mean that it cannot be qualified for R-73. The R-73 of 100 kg has to be slung on and the wing tested up to 150 kg. If the wing is fine then R-73 gets a tick.

But just because R-60 is qualified it does not mean that designers did not have the foresight to create a pylon that can take heavier loads like R-73. That conclusion cannot follow from the available information

JayS · Post by **JayS** » 09 Apr 2017 09:02

But vina claims that someone from ADA confirmed on this thread that there was wing redesign due to switch to R73 missile. I have never seen this elsewhere though.

shiv · Post by **shiv** » 09 Apr 2017 09:25

JayS wrote:But vina claims that someone from ADA confirmed on this thread that there was wing redesign due to switch to R73 missile. I have never seen this elsewhere though.

I am not able to deny that - but in the absence of information we cannot reach conclusions about lack of designer foresight.

That apart - let me simply extrapolate and state my own viewpoint.

A wing that can take 1000+ kg inboard is certified for only 60 kg outboard. Either they have done destructive testing to establish this as unalterable fact, or they have not. If they have not - the logical course would be to test a wing to its limit, confirm that there is no redundancy in design, the wing simply cannot take more than 60 kg (+ margin) (or something inadequate) and then go ahead with wing redesign. As Geeth pointed out there was also the possibility of reducing inboard loads while increasing outboard loads.

We have no information that all this failed and that the wing had to be redesigned. That does not mean that it did not happen but without data we are only chasing windmills and getting into arguments about the foresight of designers. There is no need for that.