LCA News and Discussions

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RKumar
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Re: LCA News and Discussions

Postby RKumar » 14 Sep 2010 14:49

Praise for HAL Tejas from dragon, views from otherside of boarder...

http://www.sinodefenceforum.com/world-a ... -4721.html

They also admit about couple of J-10 crashes ... would say fair discussion except normal de-railing of thread in between.

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Re: LCA News and Discussions

Postby RKumar » 14 Sep 2010 15:50

Marten wrote:RKumar, why link to such forums here?


I did not know that this forum is banned in India or on the BR. If that is the case please share with me.

Marten wrote:Do you really care what folks in China think about the Tejas?

Why we should not care about China? When they are the biggest threat to India today. Are you feeling bad that enemy is appricating Tejas?

Marten wrote:As far as one can see, Bingo is jumping around fingering the poor Chinese on that forum, and doing it systematically too!

rkumar wrote:would say fair discussion except normal de-railing of thread in between

You see, read and process what you want to sense. I see that you and I have totally different point of view but at the end we both care about our nation.

And I dont want to de-rail this thread. Admins please delete this post and other post if you feel like. If link to that forum is banned then I can also delete these myself.

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Re: LCA News and Discussions

Postby P Chitkara » 14 Sep 2010 16:40

What implications does the AOA of 28 degrees have for Tejas? MKI, F-18 etc have almost double the AOA of Tejas.

Moderators may move it to noobie forum if this question doesent belong here.

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Re: LCA News and Discussions

Postby Juggi G » 15 Sep 2010 04:19

India Sets Dec. 27 Deadline For Tejas IOC
Aviation Week
The LCA chief said that an additional 20 Tejas aircraft are on the way, bringing the total to 40.

The First 40 will be MK-1s,
While the Next 86 will be Mk-2s, with a New Powerplant.
The Indian Navy is Projected to Receive 56 of the Aircraft,
while 16 Trainers also will be Delivered.


Sources say the limited series production vehicle (LSP-5) is expected to fly very soon, with the LSP-6 (an experimental platform), LSP-7 and LSP-8 following suit.

“The engine ground run for LSP-5 is over, and we may conduct the first flight after sorting out some last-minute teething issues,” a source said.

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Re: LCA News and Discussions

Postby Kartik » 15 Sep 2010 05:22

RKumar wrote:They also admit about couple of J-10 crashes ... would say fair discussion except normal de-railing of thread in between.


There are 3 known J-10 crashes to date. But it is never mentioned almost, a by-product of the very tightly controlled media. And after all, the image of a product is only as good as the media coverage it gets. if you cover all the bad reports, issues, problems and only highlight the best, people over time start having a mythic faith in the quality of the product. For instance, it has taken years to get over the horrible publicity that the Osprey recieved for its developmental cost and accidents.

Rest assured that when (and it will as it has with any other fighter although I pray to God it doesn't) a LCA crashes, there will be the kind of media attention and media bashing that even an F-22 or B-2 crash will not bring. The usual garbage about "delays", "over budget", "IAF not happy", "not indigenous enough" and so on will start pouring out from every 3rd rate DDM journo along with headline grabbing titles like "another Widow maker or Flying Coffin in the making?"

That is what India has come to. Low grade and even rubbish levels of journalism that specialise in peddling sensationalism.

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Re: LCA News and Discussions

Postby shiv » 15 Sep 2010 06:06

Kartik wrote:
RKumar wrote:They also admit about couple of J-10 crashes ... would say fair discussion except normal de-railing of thread in between.


There are 3 known J-10 crashes to date. But it is never mentioned almost, a by-product of the very tightly controlled media. And after all, the image of a product is only as good as the media coverage it gets. if you cover all the bad reports, issues, problems and only highlight the best, people over time start having a mythic faith in the quality of the product. For instance, it has taken years to get over the horrible publicity that the Osprey recieved for its developmental cost and accidents.

Rest assured that when (and it will as it has with any other fighter although I pray to God it doesn't) a LCA crashes, there will be the kind of media attention and media bashing that even an F-22 or B-2 crash will not bring. The usual garbage about "delays", "over budget", "IAF not happy", "not indigenous enough" and so on will start pouring out from every 3rd rate DDM journo along with headline grabbing titles like "another Widow maker or Flying Coffin in the making?"

That is what India has come to. Low grade and even rubbish levels of journalism that specialise in peddling sensationalism.


Words of wisdom Kartik. But it is tied up with the low self image that Indians have about all that is Indian. You name the subject. be it aviation, deterrence, governance. India is not good enough is the cry. This often passes for patriotism.

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Re: LCA News and Discussions

Postby tsarkar » 15 Sep 2010 12:55

Since the trainer is flying well, why don’t we manufacture only trainers for the first 40? Most of IAF’s operational flying on other aircraft during peacetime is operational training for which high end performance is not required. Save airframe hours on other combat aircraft by using Tejas trainers for this activity. Intensively use these 40 trainers the same way the 18 SU-30K were used.

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Re: LCA News and Discussions

Postby P Chitkara » 15 Sep 2010 13:15

That may be one of the reasons the program is not taking anything that remotly resembles a risk and we have a far superior aircraft - for the original requirements.

At the end, it may work out beautifully for us, isnt it? The galss is 90% full, waiting for it to be completly full. :)

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Re: LCA News and Discussions

Postby Philip » 15 Sep 2010 13:18

I think with so many prototypes and LSPs flying thus far without any mishap (touch wood),orders recd. for 40+ MK1s,the thought of any rethink about the LCA should be dismised from mind even if there is (God forbid) any glitch.One must only wait for the re-engined MK-2 to complete its trials ,which will be neccessary becaue of any fuselage modifications no matter how small,before the entire programme can achieve "supersonic" production before the entire programme,erfecting the naval LCA will be a great step forward.With a large succesful IN order in hand,one could even see the possibility of exports to countries who also operate small carriers.

For a long time there has been the Q why an LCA trainer was not developed earlier,as our trainer shortage is well known.There is also a huge international market for jet trainers which can also be used for COIN and limited strike/GA roles.Italy is achieving much success with its new attack trainer and even the Sino-Pak Karakorum trainer has been exported.Hd it been developed earlier,we wouldn't have needed the additonal Hawks.

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Re: LCA News and Discussions

Postby Juggi G » 16 Sep 2010 03:11

Indian LCA Undergoing Sea Trials
Aviation Week
Indian LCA Undergoing Sea Trials
Sep 15, 2010

By Anantha Krishnan M.
BENGALURU, India

India’s Tejas Light Combat Aircraft is currently undergoing sea trials at NAS Hansa, at Dabolim in Goa.

This is part of Tejas’s out-of-station flight-test plan, with pilots from the Bengaluru-based National Flight Test Center performing high angle-of-attack (AOA) maneuvers.

A source tells AVIATION WEEK that Tejas will undergo parameter identification (PID) and sea-level flutter vibration tests, with an all-external stores (bombs, fuel tanks, missiles) configuration.

“The PID is done [with] latest software version of the digital flight control computer being developed by the Aeronautical Development Establishment,” the source says. “There are many system integration checks and weapon modes to be tested. We need to check some more sea-level performance points in high-AOA mode.”

The Tejas took part in earlier trials at NAS Hansa, during which it fired a missile, and will undergo extensive weapon testing next month. A large contingent of engineers, scientists, pilots and ground crew are in Goa for the trials, which will continue until next week.

Five Tejas aircraft from the flight line are expected to participate in the sea trials.

“Radar assessment at sea level for air-to-air and air-to-sea mode will also be tested,” the source says. “The Tejas will be flown at different altitudes and Mach numbers, while the flutter test will be done with various external configurations.”


The trials are critical for the Tejas program, which is moving toward completing all pre-initial operational clearance requirements.

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Re: LCA News and Discussions

Postby Kartik » 16 Sep 2010 04:14

P Chitkara wrote:What implications does the AOA of 28 degrees have for Tejas? MKI, F-18 etc have almost double the AOA of Tejas.

Moderators may move it to noobie forum if this question doesent belong here.


yaar, go back a few pages and read about that..I've already pointed out that the Gripen and Rafale have 28 deg AoA max. All this double shouble AoA business is really getting tiring now. Operational AoA limits are very different from some high AoA test where a spin parachute will be attached to allow for the fighter to recover after it has stalled.

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Re: LCA News and Discussions

Postby Kartik » 16 Sep 2010 04:59

Philip wrote:For a long time there has been the Q why an LCA trainer was not developed earlier,as our trainer shortage is well known.There is also a huge international market for jet trainers which can also be used for COIN and limited strike/GA roles.Italy is achieving much success with its new attack trainer and even the Sino-Pak Karakorum trainer has been exported.Hd it been developed earlier,we wouldn't have needed the additonal Hawks.


Primarily because till the LCA single seater TD-1 and TD-2 had flown (which were the ADA's main mandate for a combat fighter, not a trainer), there was no guarantee that the program would even continue further. It was TD-1 and TD-2's successful completion of flight tests that allowed the money to be released for the PVs and gave the IAF and GoI the confidence to give the go-ahead for further development as well as creation of trainer and naval variants..in that time, since the early 2000's, they've pretty much developed 3 versions side-by-side with the LCA, LCA trainer and the N-LCA.

your question regarding the LCA Trainer being used to overcome the trainer shortage can be answered using the chicken and the egg question..can the chicken be sold in the market or satisfy your family's own hunger before the egg is hatched ?

It wouldn't have been possible to get the LCA Trainer into service ANY FASTER than the LCA single seater air force version unless the IAF would accept a trainer that had an envelope that was still left unexplored and we know what the IAF's position on this would've been. Anyway, the fact that DRDO is setting up a commercial arm like Antrix of ISRO, to market and export indigenous weapons is heartening news and is vital for India's aerospace industry to truly become world class..once business and foreign customers become a focus point, quality, timelines, product support, all of the alleged bogey points of the DRDO will automatically have to be sorted out.

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Re: LCA News and Discussions

Postby archan » 16 Sep 2010 09:38

libraguy wrote:Any idea what was it today morning around 9:10
Sounded like quite a few fighters taking off within a min or so

Please see your PM inbox, and respond. Thanks.

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Re: LCA News and Discussions

Postby shiv » 16 Sep 2010 09:53

tsarkar wrote:Since the trainer is flying well, why don’t we manufacture only trainers for the first 40? Most of IAF’s operational flying on other aircraft during peacetime is operational training for which high end performance is not required. Save airframe hours on other combat aircraft by using Tejas trainers for this activity. Intensively use these 40 trainers the same way the 18 SU-30K were used.


I suspect that dedicated trainers with supersonic capability are most useful only for that "type". ie MiG 21U is most useful for MiG 21 and Tejas trainer is most useful for Tejas. A general "advanced" trainer in this day and age comes with software capability to emulate different types of aircraft and is designed from concept stage to do that. I don't think the Tejas trainer has been designed to do anything other than train for Tejas.

Just my guess..

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Re: LCA News and Discussions

Postby vina » 16 Sep 2010 11:18

I don't think the Tejas trainer has been designed to do anything other than train for Tejas.


True. But I do think that EADS made an offer , now that their MAKO trainer is canned to use the Tejas trainer into a full fledged trainer with that broader capability you were alluding to, including jt marketing , development and sales to 3rd parties.

Dont know if India will bite, given that we have invested in the Hawk AJT.

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Re: LCA News and Discussions

Postby tsarkar » 16 Sep 2010 11:34

shiv wrote:
tsarkar wrote:Since the trainer is flying well, why don’t we manufacture only trainers for the first 40? Most of IAF’s operational flying on other aircraft during peacetime is operational training for which high end performance is not required. Save airframe hours on other combat aircraft by using Tejas trainers for this activity. Intensively use these 40 trainers the same way the 18 SU-30K were used.


I suspect that dedicated trainers with supersonic capability are most useful only for that "type". ie MiG 21U is most useful for MiG 21 and Tejas trainer is most useful for Tejas. A general "advanced" trainer in this day and age comes with software capability to emulate different types of aircraft and is designed from concept stage to do that. I don't think the Tejas trainer has been designed to do anything other than train for Tejas.

Just my guess..


Shiv & Vina, I referred learning and practicing concepts like CAP, close combat, strike, interdiction, CAS, etc, and not simply type training.

Presently, these are conducted post type conversion, and lot of type airframe hours are used up learning and practicing these concepts.

What I meant was replicating the Fiza’ya SOP of teaching these concepts and honing them on A-5 and F-6/F-7 before moving on to Mirage and F-16. They have been doing this for years, and IMO, its a very effective strategy.

We can train these concepts in Tejas Mk1, that doesnt require bleeding edge performance, and save airframe hours of the seasoned combat fleet.

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Re: LCA News and Discussions

Postby Lalmohan » 16 Sep 2010 13:47

networked mission simulators
hell of a lot cheaper than airframes

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Re: LCA News and Discussions

Postby Arya Sumantra » 16 Sep 2010 15:10

Kartik wrote:Rest assured that when (and it will as it has with any other fighter although I pray to God it doesn't) a LCA crashes, there will be the kind of media attention and media bashing that even an F-22 or B-2 crash will not bring. The usual garbage about "delays", "over budget", "IAF not happy", "not indigenous enough" and so on will start pouring out from every 3rd rate DDM journo along with headline grabbing titles like "another Widow maker or Flying Coffin in the making?"

That is what India has come to. Low grade and even rubbish levels of journalism that specialise in peddling sensationalism.


So why not conduct deliberately a "Destructive Test" and (label it the same with prior publicity) for unexplored part of the envelope and unexplored weight shavings? Since it is a destructive test it was intended to crash to begin with. So journalists and their paymasters cannot say anything !

Take the plane to a great height and then explore it incrementally in steps to the extremes of the envelope. The moment it fails, the pilot ejects using safety seat and parachute. Due to the great altitude of such a test, there is ample time for test pilot to eject safely.

Same way for weight shavings (and this one could be expensive), create prototypes with gradually more and more weight shaved off its various parts like undercarriage i.e. reduced overengineering and test them to destruction at high altitude and test-pilot escape. We might actually be able to save the tested prototype as well with parachute mechanism like one explored for HPT32.

When we don't have experience like aerospace majors we create the databank the hard physical way.

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Re: LCA News and Discussions

Postby JTull » 16 Sep 2010 16:00

Arya, A pilot is not a monkey (with due respect to animal lovers here) that can be asked to deliberately eject from a fighter. There are inherent risks involved and should be used as a last resort. Morever, AFAIK even if everything goes as expected after 2-3 ejections in a career the pilot could be grounded forever. Nothing to do with his ability but the potential life-threatening risks of another potential ejection in case of emergency.

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Re: LCA News and Discussions

Postby Surya » 16 Sep 2010 16:10

Ejections cause trauma to the body with high G forces


Vertebrae compression for one although many a times its temp

some pilots get medically grounded after that.

So its not a trivial thing

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Re: LCA News and Discussions

Postby Pratyush » 16 Sep 2010 16:18

^^^ Regarding the LCA crashes and the lack thereof. If the design was sound and the integration of various components was perfect. There is no reason why it should crash. Also, the ADA must have been very conservative in conduct the flight tests. Every variable tested and similated in the wind tunnel before the actual in flight test took place. So it is tribute to the meticulus pnanning by the ADA that no crashes have taken place in the test programe.

No reason why we should wish for an accident today. Just to destroy the perfect record of the LCA.

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Re: LCA News and Discussions

Postby Gaur » 16 Sep 2010 16:20

Arya Sumantra,
:shock:
I do not mean to sound condescending but I am seriously finding it difficult how one can suggest these ideas? Was this supposed to be a joke?

The aircraft designers have a fairly good idea regarding the limits of the a/cs. However, aircraft designing is a risky process and the aircraft may sometimes behave in unexpected ways. The development of Su-27, Gripen etc are a testament to this fact.
So, the hope is always that the aircraft will perform according to the the predictions of the designers but there are so many factors involved that no one can be 100% sure. So, the aircraft's limit is tested in incremental basis. If ADA were to announce that they were doing an intentional "destructive testing", what will ADA do if all goes well during the tests and the a/c does not suffer any malfunctions? Crash the aircraft anyways? Do you have any idea regarding the time and effort to build a new prototype?
Your post also suggests that the aircraft should be used to perform maneuvers even beyond the predicted flight envelope and see if it can do it. Well, the chances of an a/c to do that will be next to nothing. And if by some chance it would be able to some of the maneuvers beyond its projected envelope, there would be no guarantee that the a/c would not crash doing that same manuever next (or 10th) time. So, your idea would yield nothing except for the loss of aircraft and probably the pilot too.
You think that it is safe to eject at high altitudes? Nothing can be further from the truth. The combination of factors (g-force, orientation and the motion of aircraft to name a few) make it very dangerous to eject at any altitude. The pilot is always facing the risk of permanently disabling injury or worse while ejecting. And on top of that, you want the pilot to eject while the aircraft is performing extreme maneuvers?

And as for your advice regarding shaving off the weight, it is now becoming difficult for me to believe that I am reading this for real. The aircraft is over engineered because it has to withstand the stress of being flown for thousands of hrs over the period of 30-40 years. Sure, you can shave of 1000kgs and flow it for number of tests and maybe nothing would go wrong. But what guarantee would you have that the aircraft would be able to withstand the stress after even one decade.

And you want to use parachute on a 5700 kg aircraft nosediving at supersonic speeds or perhaps facing a spin? Well, good luck with that.

I mean no disrespect but I would suggest that you give such suggestions at newbie thread. There is no shame in that. When in doubt, even many respectable and knowledgeable oldies post queries there.

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Re: LCA News and Discussions

Postby Arya Sumantra » 16 Sep 2010 19:55

Gaur wrote:I mean no disrespect but I would suggest that you give such suggestions at newbie thread. There is no shame in that. When in doubt, even many respectable and knowledgeable oldies post queries there.


Reply posted in Newbie thread

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Re: LCA News and Discussions

Postby Kartik » 16 Sep 2010 21:52

Arya Sumantra wrote:So why not conduct deliberately a "Destructive Test" and (label it the same with prior publicity) for unexplored part of the envelope and unexplored weight shavings? Since it is a destructive test it was intended to crash to begin with. So journalists and their paymasters cannot say anything !

Take the plane to a great height and then explore it incrementally in steps to the extremes of the envelope. The moment it fails, the pilot ejects using safety seat and parachute. Due to the great altitude of such a test, there is ample time for test pilot to eject safely.



if you've written this tongue in cheek then fine, otherwise its quite a ridiculous idea in itself. Hardly worth discussing, far less implementing. No test will ever be carried out knowingly putting the life of the crew at risk. There is inherent risk always, but with a stated goal of taking the aircraft past its limits and crashing it ? Never.

Same way for weight shavings (and this one could be expensive), create prototypes with gradually more and more weight shaved off its various parts like undercarriage i.e. reduced overengineering and test them to destruction at high altitude and test-pilot escape. We might actually be able to save the tested prototype as well with parachute mechanism like one explored for HPT32.

When we don't have experience like aerospace majors we create the databank the hard physical way.


Some of it is already done this way. For instance, with composite panels there will be plenty of sample/ coupon testing being carried out to determine failure limits and develop allowable material data.

What is way too expensive and time consuming is to create a prototype and "test them to destruction" with a possible loss of crew life as well (since you cannot guarantee that it won't fail at a critical time). IMHO, you need some real world experience to know that these things are not feasible and will not be done.

BTW, Spin tests are carried out with spin parachutes that may give the pilot valueable time to try and recover from the spin and then discard the parachute..but the HPT-32 type parachute which brings the aircraft down to the ground is not feasible for testing.

They will cautiously explore the corners of the flight envelope (low speed and low altitude, low speed and high alt, high speed and low alt and high speed and high alt) and eventually it will be there by the time the Tejas reaches FOC in 2012.

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Re: LCA News and Discussions

Postby shiv » 17 Sep 2010 05:59

Arya Sumantra wrote:
Take the plane to a great height and then explore it incrementally in steps to the extremes of the envelope. The moment it fails, the pilot ejects using safety seat and parachute. Due to the great altitude of such a test, there is ample time for test pilot to eject safely.


1) Ejections invariably cause some spine damage.
2) After a crash it is impossible to tell exactly which part of which component failed - i.e to reconstruct the cause of the crash So a destructive test may fail to give any info.

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Re: LCA News and Discussions

Postby P Chitkara » 17 Sep 2010 12:32

I met a retired Air Commdr who in his younger days had to eject from a Mig-21. He said he was lucky to be able to ever fly again. His flying status was restored after more than a year of the ejection.

Ejecting form an aircraft is much more serious than it looks.
Last edited by P Chitkara on 17 Sep 2010 13:04, edited 1 time in total.

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Re: LCA News and Discussions

Postby Lalmohan » 17 Sep 2010 12:52

typically, due to vertebral compression, the pilot will shrink by 3-4 inches in height

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Re: LCA News and Discussions

Postby vcsekhar » 17 Sep 2010 14:48

Lalmohan wrote:typically, due to vertebral compression, the pilot will shrink by 3-4 inches in height

Thats a bit of an exaggeration :)
I have met a couple of guys who ejected from their fighters and they did not report any loss of height :wink: Yes, they did suffer from spinal compression and it took a long time for them to get back to flying.
Also, there is a hard limit on the number of times you can eject, once you are past that you are not allowed to fly fighters.

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Re: LCA News and Discussions

Postby Lalmohan » 17 Sep 2010 14:52

vcshekshar, it is what i was told by some serving air force pilots... but possibly effects vary and either way the spine is damaged/weakened

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Re: LCA News and Discussions

Postby shiv » 17 Sep 2010 15:37

The spine consists of bone cylinders filled with sponge-like bone which can get crushed by extreme compression. At the very least there are micro-fractures that heal over several weeks. Significant overt fractures can occur - but "loss of hight" of several cm is only at the instant of extreme upward acceleration. The spine springs back to normal - but major fractures at that stage can cause a permanent loss of height of a few cm.

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Re: LCA News and Discussions

Postby Lalmohan » 17 Sep 2010 15:44

i was told that individuals had to undergo traction treatment etc., to be brought back to normal

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Re: LCA News and Discussions

Postby shiv » 17 Sep 2010 16:08

Lalmohan wrote:i was told that individuals had to undergo traction treatment etc., to be brought back to normal


If there is permanent damage traction will not help. In some instances traction helps in relieving compression of nerves and reducing pain after which here is a period when the person walks about with some sort of brace. Unlikely that any of these people ever go back to fighter flying- though transport and helos are a possibility.

Having said that, all ejections cause some damage, but all ejections do not lead to serious damage.

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Re: LCA News and Discussions

Postby vcsekhar » 17 Sep 2010 16:25

Something to add here... there is a significant difference in the way the old Mig21 seats were designed as compared to the some of the western or newer russian seats.
I was told that if you ejected out of a Mig21, the experience was like a bomb went off under you and you were violently thrown out of the cockpit and the likely-hood of a injury was higher. If however you ejected out of a modern seat (for ex the harrier seat) the experience was like you were pushed up very fast by a rocket motor (the seat does have a small rocket motor) so the chances of injury were much lower (relatively).

All ejections come with significant risks and cannot be taken lightly. And all the pilots have to go through a battery of physiological tests to get back to flying.

Just my 2 Cents.

chandrasekhar


shiv wrote:
Lalmohan wrote:i was told that individuals had to undergo traction treatment etc., to be brought back to normal


If there is permanent damage traction will not help. In some instances traction helps in relieving compression of nerves and reducing pain after which here is a period when the person walks about with some sort of brace. Unlikely that any of these people ever go back to fighter flying- though transport and helos are a possibility.

Having said that, all ejections cause some damage, but all ejections do not lead to serious damage.

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Re: LCA News and Discussions

Postby Kartik » 18 Sep 2010 04:38

I'm surprised and rather frustrated that till date no single article has appeared detailing all the changes that are planned on the Tejas Mk2 in anything more than just the most generic fashion..all we have upto now is hearsay on the increase in the size of the intakes, improved aerodynamics (how, none of us jingos know), possible increase in wing surface area (span maybe?) and the possible addition of an AESA radar..what else ? What other improvements in avionics, cockpit, weapons, datalink, EW suite, countermeasures, etc. ? there is no real data on all this and its been more than a year since the Mk2 was announced..heck we've not even seen any CAD or line drawing that illustrates these changes ! developing 2 separate engine bays (and possibly intakes) for the F-414 and Ej200 may be alright for the preliminary stage when the engine has not yet been selected, but the complete silence on all these issues is really really frustrating.

ADA does identify 1 single person on their website as being the head of the Tejas Mk2 development team, so it would be nice if Ananth Krishnan or Ajai Shukla did a detailed report on the changes that are planned for the Mk2 and showed some schematics of how different it may look..Now that they have a Bangalore Defence Journo Forum in place, maybe more jingos can look to join it and take advantage of the access to DRDO. There is enough masala and meat in all the LCH, ALH, LCA programs to keep a serious aero-journo occupied for a good deal of time simply collating all the information and producing a sort of developmental history of these products..unfortunately, no one seems to be doing it in India..if only Harry were still around with his superb ACIG.org series or articles that explored things in such great depth..:(

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Re: LCA News and Discussions

Postby Wickberg » 18 Sep 2010 05:15

Just a question...

If the LCA mk2 needs "improved aerodynamics" does that mean that the MK1 design was faulty?

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Re: LCA News and Discussions

Postby Arya Sumantra » 18 Sep 2010 05:21

Since folks have chosen to beat the same point which I modified in my subsequent post (in newbie thread at someone’s instance), here I re-quote myself
Ok I will take it that I goofed up on Test-pilot ejection at extremes of envelope part and my apologies to all pilots. But how technically challenging it is to program an auto-pilot into doing the same, that is - repeating a specific manouever with incrementally increased aggressiveness ? And doing this over an uninhabited area like the ocean airspace.

We already have shore based facility in goa. How challenging is it for an autopilot to take off into marine airspace and conduct pre-programmed manouevers in increments till failure? In this day and age when unkil is converting F-solah into drones, drdo is working on long endurance UAVs and Chetak is being converted into NRUAV, it is no longer a science-fiction.

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Any testing on ground is based on loading conditions that YOU THINK applies on the structure based on simulated conditions and your ability to replicate that with point loading. A destructive test replicates testing under realistic conditions. Any person no matter how much an expert at FEM knows that there is significant difference in results with simulations and realistic conditions. The data obtained from unmanned destructive tests will help finish remaining manned trial flights for certification with much more audacity and in shorter time.

Shiv wrote: 2) After a crash it is impossible to tell exactly which part of which component failed - i.e to reconstruct the cause of the crash So a destructive test may fail to give any info.

Sir ji, think about real-time data that would have been transmitted back before that. Retrieving the failed specimen intact is only one part. The different parts of the airframe structure can be patched with sensors somewhat similar to a health monitoring system on MKI and real-time data on stress state at extremities of envelope be transmitted to the ground testing crew. More realistic data about loading conditions than simulations.

Gaur wrote:Sure, you can shave of 1000kgs and flow it for number of tests and maybe nothing would go wrong. But what guarantee would you have that the aircraft would be able to withstand the stress after even one decade.

Agreed that a single-use destructive test tells more about ability to withstand the load one-off rather than fatigue behavior.
For fatigue studies, a destructive test need not be finished in one flight. It only means flying until failure- whenever it happens. The plane under test can return back to replenish fuel and maintenance of all things EXCEPT the airframe such as engines, subsystems etc and return to flying under high stress envelop extremes. This would be an accelerated fatigue test to estimate airframe lifetime but in realistic conditions.
Frankly it would not matter if the fatigue life of an indigenous airframe was say 5 years less than an import. As long as we could determine how much its lifetime is, we could replace the airframe with newer one. It surely wouldn’t cost an arm and a leg like the imports.

Kartik wrote:What is way too expensive and time consuming is to create a prototype and "test them to destruction"….

That’s because you are thinking about absolute costs of prototype and NOT how much the time lost(till now & future) will cost in terms of alternative purchases, delay in induction etc

Kartik wrote: They will cautiously explore the corners of the flight envelope (low speed and low altitude, low speed and high alt, high speed and low alt and high speed and high alt) and eventually it will be there by the time the Tejas reaches FOC in 2012.

This isn’t about only MK1 and its residual testing. The reason this is important is because we have MK2 as well in pipeline which being a different plane will have to start testing from scratch. Surely no one’s enthusiastic about waiting as long for its testing all over again.

By conducting meticulously planned unmanned destructive tests of MK2 verifying extremities of the envelope, the subsequent manned flight trials with within-envelope manouevers can be conducted at very high frequency to finish certification in shorter time.

JMT

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Re: LCA News and Discussions

Postby Arya Sumantra » 18 Sep 2010 05:24

Wickberg wrote:Just a question...

If the LCA mk2 needs "improved aerodynamics" does that mean that the MK1 design was faulty?


Does Grippen having better aerodynamics mean Viggen and Draken were "faulty"?

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Re: LCA News and Discussions

Postby Kartik » 18 Sep 2010 05:31

Wickberg wrote:Just a question...

If the LCA mk2 needs "improved aerodynamics" does that mean that the MK1 design was faulty?


I'm not sure if faulty is the way to describe it. But they're taking the chance to improve upon the existing aerodynamics.

The way you put it, the Gripen NG is "improved" because the C/D is faulty ? or the C/D was done because the A/B was faulty ?

Don't bother to troll here.

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Re: LCA News and Discussions

Postby shiv » 18 Sep 2010 07:54

Arya Sumantra wrote:
Shiv wrote: 2) After a crash it is impossible to tell exactly which part of which component failed - i.e to reconstruct the cause of the crash So a destructive test may fail to give any info.

Sir ji, think about real-time data that would have been transmitted back before that. Retrieving the failed specimen intact is only one part. The different parts of the airframe structure can be patched with sensors somewhat similar to a health monitoring system on MKI and real-time data on stress state at extremities of envelope be transmitted to the ground testing crew. More realistic data about loading conditions than simulations.


Arya Sumantra it doesn't work that way. You idea is good - it may be for the future. Currently it is not feasible.

I was very close to my cousin late Wingco Suresh when he set up the Military Flying Accident database in HAL (in the 90s). He and another (now retired) civilian whom I know well used to leave town and visit the site of every IAF crash and do the investigation. I got a fairly clear idea of how difficult it is to pinpoint the cause of a crash even after all possible data is present. At that time I was writing software to help diagnose obscure abdominal pain - being a doctor with some programming knowledge. I wanted to see if the same structure of the expert system could be applied to investigation of flying accidents.

If the pilot survives - fine. If not you have a dead body and a burnt and badly damaged aircraft. You don't know if the flight control software failed, whether it was a bird hit, or whether an engine blade separated, or whether a fuel line was clogged, or whether a structural component failed, the pilot became disorientated or what. Aircraft are very very complex systems. You cannot monitor every structural component, engine blade and washer, valve or pump for failure.

I presume you have read this accident investigation story on BR that show the complexity of figuring out what went wrong.
http://www.bharat-rakshak.com/IAF/Histo ... aguar.html

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Re: LCA News and Discussions

Postby sumshyam » 18 Sep 2010 09:03

LCA-Tejas has completed 1428 Test Flights successfully. (17-Sep-10).


* (TD1-233,TD2-305,PV1-242,PV2-165, PV3-229,LSP1-59,LSP2-158,PV5-17, LSP3-14,LSP4-6)


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