LCA News and Discussions

[suryag]

where is IOC-2?

[Sagar G]

Wait for a few more months and it will happen.

[Lalmohan]

dont see why the probe has to be retractable...

[SaiK]

few things: cleaner visibility when not in use, and reduced drag (how much ever delta variation that may be). now tradeoff with the space & weight gain by not using one. i guess, the design will largely drive at using one.

[Lalmohan]

in a small aircraft, a retractable probe is a design problem - lots of aircraft have fixed probes
they can also aid situational awareness by providing a handy reference point

[SaiK]

are you saying.. that pic with requirement texts, shows a design problem?

[Sagar G]

^^^ I think he is saying the same thing which the Cobham guy said i.e. putting in a retractable fuel probe in an already tightly packed aircraft is going to be a design challenge.

[SaiK]

I agree, but which (constraints) were given ahead ... if cobham would not have analyzed the risks of committing to such a design, then they would not proceeded to work with Tejas team (if they have started designing it).

btw, in my definition of understanding:
problem : something roadblocked - redesign issues, and can't proceed further
challenge: something where a way is found but heavy constraints, doable on re-design.

[Sagar G]

Any design problem is a design challenge to be overcome so saar bhaavnaon ko samjho onlee

[SaiK]

slight correction: design challenge [previous state] can become a design [next state], if done correct. and if done wrong, it becomes design problem.

[Lalmohan]

have you chaps looked inside an aircraft's nose lately?

[Sagar G]

Only in photus, what's your point ??

[SaiK]

before someone jumps in, i want to say, there is no right or wrong design, but what is correct to the requirements. so if requirements are correctly specified, there exists least issues ahead. IMHO, only certain constraints can become challenges. beyond a point, there is no point cutting legs/clipping nails for already purchased shoe.

[ajay_hk]

For those wondering why PV1 is not being flown - details below: it was getting outfitted with EW systems!!

Posting in full as it might not get archived.

Finally, Tejas gets electronic warfare systems
Prashanth G N, Bangalore, Oct 16, 2013

DHNS:After eight years of research and postponement, India’s first indigenous light combat aircraft (LCA) Tejas, positioned at HAL Bangalore, has finally been fitted with electronic warfare (EW) systems.

Now, new test flights will happen with electronic warfare anytime during November or beginning of December. The 2,348 test flights of the LCA so far have not had electronic warfare. The new test flights will bring in new data and information for further development of the aircraft and the electronic systems.

Sources in the Defence Research and Development Organisation (DRDO) told Deccan Herald that the LCA Prototype Vehicle-1 (PV-1) has now been fitted with a radar-warning receiver, a radar-warning jammer, laser warner, missile-approach warner, emitter, and a flare dispenser. The systems are now undergoing ground trials with aeronautical engineers simulating multiple threats to the aircraft and then examining its response.

The results of the ground trials will help fine-tune the electronic systems for the actual test flights. The ground trials will take about a fortnight or a month. So, test flights will be held in mid-November or December.

Engineers and scientists working on the project say the radar receivers and jammers will track enemy signals from air and ground, while the emitter will watch out for missile launches from ground. Systems to track missiles from air and enemy aircraft will also be part of the LCA. The entire system has been developed by both Indian and Israeli engineers and scientists. is this Mayavi?

The fitment of the electronic systems has an interesting history. For almost eight years, a section of the aeronautical community has been resisting its fitment, anxious that the add-ons may cause a first crash, which has never happened so far in the LCA’s test-flight history. They have been very keen on securing the operational clearance, initial as well as final from the Indian Air Force, even if the LCA did not have the electronic system.

Their reasoning was that once the IAF certified it as operationally worthy, they would have a successful product to showcase to the world. Also, the LCA has had a perfect record of test flights and no one wished to risk an add-on on the LCA that had not been tried. The idea was to defend the ‘zero crash’ record.

This was made known sometimes explicitly to engineers and scientists working on the electronic systems, who, however, had been pressing for very long that the systems ought to be fitted and trials conducted to be able to fine-tune them. This difference of perception on the LCA persisted for long, and one consequence was, no vehicle or version of the LCA was identified for many years to fit the equipment. This caused delay of over five years in launching the electronic systems on the LCA and to questioning of the very purpose and objective of building the systems.

After haggling for over eight years, it has been finally decided to instal the electronic systems on the LCA prototype Version-1. But there’s a catch here. The PV-1 has not flown for very long and has been parked in the hangar with later versions of the LCA undertaking the test flights. The PV-1, which began flights in around 2001-02, has completed 242 test flights after which it has been grounded. Now, there is a bit of anxiety about how an aircraft that has not done flights for long will perform with the new electronic warfare systems.

The confidence, however, is that the aircraft may perform well because its health has been under check almost daily and every department concerned will certify that all parts of the aircraft are flight-worthy. Without this certification, the PV-1 will not be allowed to fly. But once it passes the certification, the LCA PV-1 will become the first vehicle to fly with electronic warfare systems.

[Karan M]

Seems to be a lot of misattribution about flight safety. India does have EMI/EMC testing capability and would do so. Simpler explanation is that the system is finally ready for advanced trials having been matured. The Israelis helped in the development of the jamming portion of the subsystem but the RWJ is locally produced. Have posted before (see my and pragnya's posts) on the same.
No, its not the Mayavi but as posted before the aptly named RWJ- Radar Warner Jammer, developed by DARE. A variant is being fitted to the MiG-27 Upg, whereas a more powerful version (replacing the jammers with AESA ones) is being fitted to the MiG-29 Upg. Limited info as of yet on what DARIN-3 will have.
The news about MAWS, LWS is interesting and new.

[SaiK]

How many of these LRUs are podded vs. integrated? good news by the way!

[suryag]

Ajai Shukla reported atleast three/four years ago that PV-1 was not being flown because it was being outfitted with EW equipment. During that time the consensus amongst Arm chair generals here was that it would be like F-18 prowler(part podded part embedded)

[Philip]

One can't understand what the reluctance was.Surely in the present day and age,a frontline combat aircraft without EW,etc. would be at a severe disadvantage against a 4th gen or even 3++ foe? The problem is that there is perhaps hardly any space left for adding vital components let alone an inflight refuelling probe.There was an interesting invention that a pilot is patenting,a drawer containing cockpit avionics which slides out as in a desk drawer.The time and effort spent in trying to repair/replace avionics in small cockpits resulted in his brainwave.What used to take a few hours now takes a few minutes.From various reports over the last few years one continuing problem with the LCA has been a lack of internal space .It was also said that every prototype flying differed internally and that there was no standardised LSP aircraft that could go into series production.Whether that issue has been resolved is a moot point.

Coming back to the original concept,as the late Air Cmde. Jasjit Singh has written,it was originally intended to be a light,low-cost incremental replacement for the MIG-21,meant for "battlefield support" of ground forces ,to be the "workhorse" of the IAF (Arun Singh),about 450 to have been planned for.The 3 key deficiencies in the MIG-21 were to have also been resolved.(more in the Ind.av. td.)The bulk of IAF ops was at low level and the air force was expected to engage the enemy at very low alts. and penetrate hostile air space at tree-top level.But as he says,the aircraft's std. was "hyped" into a fighter pilot's dream and we ended up making the same mistakes that were made with the HF-24.The LCA became a smaller version of the M-2000,"a jack of all trades,master of none".When we have MKIs,and MIG-29s,with UG versions of the MIGs and M-2000s in the pipeline,not to mention the Rafale,to handle longer range multi-role ops,why on earth are we now trying to shove in an inflight refuelling probe which will only delay further the introduction into service of the aircraft,which should be used primarily as a point defence fighter? From current trends,it will take another 4-5 years before a heavily redesigned MK-2 arrives in production.JS alsos says that HAL's design capability has been "emasculated" by the ADA under the DRDO.This explains why we hear of SAAB,Cobham and others getting involved (rather late in the day) of one aspect of the aircraft or another.

By then will the IAF want it when the MMRCA,and other upgraded Sukhois,far more capable aircraft will be in service and more modern aircraft with our rivals? HAL should get its production facilities for MK-1 up and running and a rate of far more than a measly 8 per year as has been mentioned.

[SaiK]

My main area of concern is reflected in what Dr. Saraswat was lamenting about.. we have a gap in production engineering and management of technology, that catching up there should be the drain for Mk-2 capabilities establishments.

Mk.1 must happen in parallel with Mk.2 for economies of scale production. Concurrent engineering just does not happen in the labs.

Perhaps we should not look ourselves like boeing or lm anytime soon (i mean by decades in measure).

[karan_mc]

if i remember correctly PV-1 will also be integrated with Kaveri engine , when ever that is ready

[Kersi D]

I will try. It was conceived in 1970's. I had the history once (2006?). I cannot pin the correct year now as i lost it. There was a mention of it in 1971 and probably culminated in 1973 or 74. This project is some 40 years old.

Edited (It was initially called Advanced strike aircraft. )

In the mid 1970s IAF ca,e with a concept to replace HF 24 Marut with DPSA, Deep Penetration Strike Aircraft. Nothing happened and we finally bought Jaguar

K

[Kanson]

And an old BR post:

SaurabhG

No Nandai<BR> According to the EconomicTimes. <P>The LCA was conceived in 1968 but was given the go-ahead only in 1983. <P> They are calculating 32 years from the year of conception, which was 1968, to the year of first test flight i.e 2000(begining 2001).<P>

Code: Select all

So, there is the approx birth of the LCA. (BTW, that BR thread, in 2001, on the LCA is very interesting. Not to speak of the old timers too.)

Now for the ref to the F-16C ...............................

Sirji, you know, MCA, with twin engine tailless delta wing was discussed from late 90's. Then we heard AMCA of various designs and latter changed the title to NGFA and lastly design studies were conducted for a new ASR and design studies were carried out for that. IF suppose when AMCA or NGFA or whatever be the name of the project comes to fructify, will it be right to say the project started in late 90?

It is the similar case for LCA. Pls hear it from the words of Chief Design engineer at that time(70's).

http://forums.bharat-rakshak.com/viewto ... 3#p1005373

Mr Pushpinder Singh sent an old article ” THE LOST DECADE”, of the 1970s, which appeared in the Nov – Dec 1990 issue of Vayu. The author, Mr Raj Mahindra, was former MD (Design and Development) at HAL. The article, written to mark the 50th year of Hindustan Aeronautics Limited, basically reviews the plans and projects that were considered and undertaken by HAL during the “lost decade and to speculate on what might have been had the powers-that-were persisted with the several opportunities that came up.”

We all hold opinions on HAL and its achievements, that is why this particular account, from within the establishment is of interest. One may agree or disagree with the contents, but there is no denying the fact that it makes for very interesting reading.

Without reproducing it in its entirety, I have paraphrased parts of it while resorting to direct quotes, wherever it was deemed appropriate. All italics and highlighting are mine.

The article begins with briefly recalling ASRs formulated at Air HQs in the 1970s, which discussed the gradual replacements for the MiG 21FL, Su-7, Hunter, HF 24, Canberra, the Vampire trainer and the aging transport fleet. These in turn were to be replaced by a single supersonic tactical airstrike aircraft (TASA), supersonic deep penetration aircraft, the AJT and versatile STOL transport aircraft respectively.

“In Hindustan Aeronautics Limited (HAL), the Indian Air Force, indeed the nation had an enormous reservoir of opportunity to meet the IAF’s requirements for most, if not all, its needs of the forthcoming generation from the mid-70s till the end of the century.” Till the 60s, HAL’s list of achievements boasted the HT-2, Pushpak, Krishak and Basant. The Kurt Tank led team also had the inducted into service HF 24 under its belt by the mid 60s. The search for a compatible engine, for the Marut, to match its superb design capabilities and which came to nought, was attributed to be “more due to lack of sustained Government/industry effort than technological reasons.” Once the Marut was consigned to history , the design and development team of the HAL were virtually jobless till the LCA project was launched in 1986. “Meanwhile, a great deal of experience, talent and time had been irretrievably lost.”

Aircraft design and development, according to the author, briefly comprises three distinct streams – where prototypes are built but not followed by series production, where prototype development is followed by production and operational deployment and thirdly where design studies, building of mock ups etc takes place without further follow up activity. “unfortunately, the last category was the fate of most of the efforts of HAL’s design teams in the lost decade of the seventies, a fact barely known to most and the real story, to just a few.”

During the period of the mid sixties an Advanced Projects Group, headed by the author, was assigned the task of focussing on and overseeing feasibility studies for likely military and civil aircraft.

This group initially conceived of the Ground Attack Fighter I (GAF I) powered by an M45 engine which was itself being developed as a joint venture between Bristol Siddeley and SNECMA and would have a radius of action of about 150 miles.

There was also a study made for a STOL transport cum freighter, as a civil airliner with a 100 seat capacity and also as a replacement for the Packet, Dakota and Caribou. The configuration was for using four Rolls Royce turbofan engines and another configuration powered by four turboprop engines.

“The design configuration was not only contemporary but had advanced features which were later seen to have been adopted by advanced aerospace companies in the West. Unfortunately, development work on this project was abandoned in favour of combat aircraft which had all the priorities. However, as later events unfolded, the tremendous efforts ………….did not succeed in persuading the Defence Ministry to launch full fledged design and development of even the combat aircraft …..”

In 1967, the Group took up studies for an interceptor – ground attack aircraft. The multi role F 4 Phantom was the role model of this study. The GAF II, as it was referred to, was put through wind tunnel tests and the “configuration presented a very good basis on which to launch a prototype development effort. It was, however, clear that a far more elaborate infrastructure would be required for HAL to develop and build a new generation fighter.”

In the event, an attempt was undertaken to fall back on the trusted Marut and a parallel design using the forward fuselage of the HF – 24 with some modification to its canopy contour was offered to the IAF. The aircraft would have a radius of action of 300 nm, maximum ordinance for a ground attack role with contemporary avionics. The study completed in 1970 envisaged induction into service by 1976. This did not apparently find favour and Air HQ issued a firm requirement for an Advanced Strike Aircraft (ASA). “The final configuration of the Advanced Strike Aircraft as proposed by HAL, met most of the essential requirements of the Indian Air Force. While evaluation continued for some time, approval for prototype development simply did not materialise.”

In 1973 there was an offer from Germany to jointly develop the HF 24 into the Hindustan Supersonic Strike Aircraft labelled the HSS 73 later to be known as the HF-73. This would retain the original mainframe, with radical changes to the fuselage, air intakes and the centre wing section. The cockpit was to be modified for better visibility, fuel capacity increased, and with a completely new avionics suite and powered by the Rolls Royce RB 199-34R engine would have a radius of action double that of the HF 24. “Eventually, this project had to be abandoned because, as some said, of non clearance of the RB 199 by the UK and Germany, the two partner governments involved in the engine development for the Tornado MRCA programme. Thus all efforts in developing an Indian combat aircraft had come to naught.”

Subsequently HAL took on a feasibility study for a small multi role passenger aircraft, the HAC 33. “A wind tunnel model was built but not tested as development funds, were once again, not approved.”

In the mid-70s, the IAF showed interest in development of an air superiority fighter. In 1974 HAL undertook designing and studying a configuration for the Air Superiority Fighter (ASF). The ASF 300 was considered with either an Indian GTX or a SNECMA engine. The configuration proposed by HAL, “even though it did not meet the ASR, could have provided a reasonable solution…..”

“At this stage the HAL design team, resilient as ever, projected a low cost HF-24-M53…….when compared with the ASF 300, was 2 tons lighter, and was comparable to the Jaguar for bomb carriage capability as well as penetration distance……….The combat capability offered through this configuration and the delivery schedules were not acceptable to the IAF, and therefore the work was discontinued.”

“How much disappointment does a man (or design team) need?”

There was yet another attempt made to redesign the dear old Marut and a detailed feasibility study was conducted for the next version, the HF 25. At an estimated cost of Rs 64 Crore at 1979 price levels, the HF 25 prototype was scheduled to be available in three years and induction into service was proposed seven years later, that is by 1986. “In spite of the low development cost of the project and low unit cost of the HF 25, the IAF showed preference for the Soviet MiG 23/27. The project was therefore discontinued.”

In 1980-82 design feasibility studies were undertaken for an Advanced Jet Trainer. The programme was disbanded as all available funds were diverted towards the Advanced Light Helicopter and the Light Combat Aircraft.

“It was not until 1986, thus, that the Ministry of Defence with its constituent departments encompassing the conceiver (Defence Research and Development Organisation) producer (Hindustan Aeronautics Limited) and operator (Indian Air Force) got its act together to clear the Light Combat Aircraft (LCA) project which has since been underway under the aegis of the Aeronautical Development Agency (ADA) which manages, funds and monitors the programme from its headquarters in Bangalore.”

[Pratyush]

^^^

The saddest words ever, "if only it was so". Come to mind reading the above article.

So many lost opportunities. If any of the combat aircraft proposal was approved. It would have enhanced aircraft design and developmental skills in the country.

Withe the result being, that when the LCA / or it comparable project was launched in the 80s. It may have entered service by the mid 90s. And if that, effort was taken forward, than, India may just have been flight testing its own FGFA.

[nits]

Finally, Tejas gets electronic warfare systems

After eight years of research and postponement, India’s first indigenous light combat aircraft (LCA) Tejas, positioned at HAL Bangalore, has finally been fitted with electronic warfare (EW) systems.

Now, new test flights will happen with electronic warfare anytime during November or beginning of December. The 2,348 test flights of the LCA so far have not had electronic warfare. The new test flights will bring in new data and information for further development of the aircraft and the electronic systems.

Sources in the Defence Research and Development Organisation (DRDO) told Deccan Herald that the LCA Prototype Vehicle-1 (PV-1) has now been fitted with a radar-warning receiver, a radar-warning jammer, laser warner, missile-approach warner, emitter, and a flare dispenser. The systems are now undergoing ground trials with aeronautical engineers simulating multiple threats to the aircraft and then examining its response.



The results of the ground trials will help fine-tune the electronic systems for the actual test flights. The ground trials will take about a fortnight or a month. So, test flights will be held in mid-November or December.

Engineers and scientists working on the project say the radar receivers and jammers will track enemy signals from air and ground, while the emitter will watch out for missile launches from ground. Systems to track missiles from air and enemy aircraft will also be part of the LCA. The entire system has been developed by both Indian and Israeli engineers and scientists.

The fitment of the electronic systems has an interesting history. For almost eight years, a section of the aeronautical community has been resisting its fitment, anxious that the add-ons may cause a first crash, which has never happened so far in the LCA’s test-flight history. They have been very keen on securing the operational clearance, initial as well as final from the Indian Air Force, even if the LCA did not have the electronic system.

Their reasoning was that once the IAF certified it as operationally worthy, they would have a successful product to showcase to the world. Also, the LCA has had a perfect record of test flights and no one wished to risk an add-on on the LCA that had not been tried. The idea was to defend the ‘zero crash’ record.

This was made known sometimes explicitly to engineers and scientists working on the electronic systems, who, however, had been pressing for very long that the systems ought to be fitted and trials conducted to be able to fine-tune them. This difference of perception on the LCA persisted for long, and one consequence was, no vehicle or version of the LCA was identified for many years to fit the equipment. This caused delay of over five years in launching the electronic systems on the LCA and to questioning of the very purpose and objective of building the systems.

After haggling for over eight years, it has been finally decided to instal the electronic systems on the LCA prototype Version-1. But there’s a catch here. The PV-1 has not flown for very long and has been parked in the hangar with later versions of the LCA undertaking the test flights. The PV-1, which began flights in around 2001-02, has completed 242 test flights after which it has been grounded. Now, there is a bit of anxiety about how an aircraft that has not done flights for long will perform with the new electronic warfare systems.

The confidence, however, is that the aircraft may perform well because its health has been under check almost daily and every department concerned will certify that all parts of the aircraft are flight-worthy. Without this certification, the PV-1 will not be allowed to fly. But once it passes the certification, the LCA PV-1 will become the first vehicle to fly with electronic warfare systems.

[NRao]

Sirji, you know, MCA, with twin engine tailless delta wing was discussed from late 90's. Then we heard AMCA of various designs and latter changed the title to NGFA and lastly design studies were conducted for a new ASR and design studies were carried out for that. IF suppose when AMCA or NGFA or whatever be the name of the project comes to fructify, will it be right to say the project started in late 90?

: ). At times I am my own enemy. I read 1968 as 1978. Actually it did germinate around 80-81ish and get formally approved in July of 1983.

History of NAL

[member_23360]

http://timesofindia.indiatimes.com/indi ... 356783.cms

BANGALORE: The naval variant of India's Light Combat Aircraft (LCA) is gearing up for carrier compatibility tests at the shore-based INS Hansa in Goa, according to sources in the Aeronautical Development Authority (ADA) which is developing the aircraft.

The first prototype completed its maiden flight on April 27, 2012.

The ADA has floated tenders inviting expression of interest (EoI) for the design, development, procurement, testing, integration, installation, commissioning and operation of shore-based telemetry facility, an essential component to test LCA-Navy. "The last date to receive EoIs is October 24," a source said.

LCA-Navy is the second Ski Take-Off But Arrested Recovery (STOBAR ) carrier-borne aircraft in the world, after the Russian deck-based aircraft. However, it'll be the only carrier-borne fighter aircraft in the light category.

A senior ADA official said a US Navy Carrier Suitability Test Team will audit the test findings and its experience in developing and maintaining carrier-borne aircraft will be useful.

Technical features

* Operate from aircraft carrier using Ski-jump Take off But Arrested Recovery. Aircraft gets airborne over a ski jump in about 200 m and lands in 90 m

* Derived from air force version, it's an agile war machine

* Flight control system augmented with Leading Edge Vortex Controller which aids reduced approach speeds for carrier landing

* Fuel dump system enables safe landing by reducing weight in emergencies after launch from carrier

[Austin]

I was reading an old Air International article which mentioned static instability for PAK-FA is reportedly 10% to 12% when compared to the 5% to 6% of SU27M/MKI and the neutral instability of basic SU27.

Do we know the static instability for LCA Mk1 and design goals for Mk2 ?

[SaiK]

no numbers, but it says very high
http://www.bharat-rakshak.com/IAF/downl ... diance.pdf

[SaiK]

http://www.scribd.com/doc/78345390/Appr ... -LCA-Tejas

The stability and control cycle is updated every 12.5 milli secs through highfidelity, rate and acceleration sensors and high rate control actuators. Tejas instability isdefined by ‘time to double amplitude’ and is one of the lowest amongst contemporary acin the world. Graph at Fig-2 depicts this value across a Mach vs altitude scale. Theregion from 0.5M to 0.7M and from 3Km to 8 Km is the zone of the highest instabilitywith time to double amplitude dropping to 200 milli secs. This implies that anydisturbance in pitch would cause an increase in amplitude by 32 times in a sec.

However, directional characteristics indicated the proverbial ‘cliff’ with a sudden drop inCn, CRM (Coefficient of Rolling Moment) and CYM (Coefficient of Yawing Moment) atapprox 250AoA as shown at fig-4 and 5. These phenomena require the High AoA trialsto be limited to 240(as shown in dotted line) until directional stability is bolstered andaugmented by rudder control up to an expected 26o. Currently the Tejas is flying to AoAlimits of 20oand 22onever exceed. Fortunately as shown in fig-6, the LCA hassignificant rudder authority (CYM-Del R) even up to 300AoA that will allow artificialstabilization in yaw at high AoA

[Austin]

Came across from board which quotes Eurofighter Static Instability at 8 %

[rajanb]

The TOI article above seems to be a case of DDMitis, methinks.

The ADA has floated tenders inviting expression of interest (EoI) for the design, development, procurement, testing, integration, installation, commissioning and operation of shore-based telemetry facility, an essential component to test LCA-Navy. "The last date to receive EoIs is October 24," a source said.

If the last date for EoI is 24 Oct (presumably this year) It is going to take some time for finalisation, selection, contract, install, test, yada yada. I have worked on the computers at HAL BLR in the telemetry section so have a fair idea of what goes on.

So lets not moan if delays take place because this article raises unnecessary hopes!

[SaiK]

austin, not sure on the units of measure.. we will have to call in gurus to first put the static stability formula in understanding and its units here first.. and figure out what measures we are talking - degrees of stability, directional, aoa/longitudinal, directional, lateral, ...?

paging all experts -- indranil, karan m, aoa-hakims, et al.

PS: in addition to news and discussion thread, we need only just news and links thread for such collections of articles. was there one earlier?

Suggestion: LCA - Articles & Reports - no analysis thread, just purely for reference of links and articles.

[Indranil]

Saik,

What you are asking is quite involved and will take me some time to explain. Unfortunately, currently I am a little short on time, so I will keep it short. I will use some jargon which I will enclose in quotes. If you are interested to know more, please read a little more about them.

A plane has a "neutral point" along its longitudinal axis. If your CG lies at this point, then the response of the aircraft to an angular disturbance is zero. If the CG lies in front, then the aerodynamic forces try to mitigate the angular disturbance. If the CG lies behind this point the aerodynamic forces aggravate the angular disturbance. The distance between the CG and the neutral point is called the "static margin". The larger the static margin, the more is the effect. The static margin is expressed in terms of % of the "mean aerodynamic chord". So this 8% for Eurofighter is its static margin.

Having said that the static margin for a plane is not fixed for different speeds. For example for the EF, the CG lies in front of the neutral point during subsonic flight. However for supersonic flight the neutral point moves forward (because the "center of pressure" moves backward) and ahead of the CG, making it a stable plane at supersonic speeds.

I don't know the static margin for LCA. But the way stability works is that it that the amplitude of oscillations grows or dampens in geometric progression. So if the amplitude of LCA oscillations double every 1/5th of a second, then in 1 second, it will be amplified by 2^5= 32 times.

[jahaju]

LCA-Tejas has completed 2349 Test Flights Successfully. (18-Oct-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-375,LSP1-74,LSP2-286,PV5-36,LSP3-162,LSP4-94,LSP5-220,LSP7-65,NP1-4,LSP8-31)

From

LCA-Tejas has completed 2332 Test Flights Successfully. (28-Sep-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-371,LSP1-74,LSP2-286,PV5-36,LSP3-157,LSP4-94,LSP5-220,LSP7-60,NP1-4,LSP8-28)

[srai]

^^^

Need to be on the watch for PV1-EW flight!

[jamwal]

I always thought that EW was an integral part of Tejas program. Now there is this news that no plane as ever flown with it This gives already reluctant IAF a huge stick to beat this program. Not saying that IAF wasn't aware of it.

Are these guys so unsure of their own capabilities or am I missing something about how planes are designed ? If plane crash was an issue, then how they'll fit the system on to later LSP models after testing it on the one which has been grounded for 8 frigging years ?
Something is really effed up

[srai]

This is the first time a fully integrated EW (warning, jamming, decoy and associated software/hardware) is being tested on a LCA platform. Various EW components have been tested out over the years as separate and partially integrated pieces. Some examples of this are various LCA test platforms sporting RWR (or something like it) on their tails and completing chaff/flare release trials in Goa and in recent training operational exercise.

[negi]

Well EW suite integration is a big deal the pace of the testing does not bother me; the way I see things fighter platforms today have more or less stagnated in terms of core capabilities (honestly if Tejas was a wee bit bigger it would have been pretty much in same class as any of the MMRCA contender and for anyone's first/second fighter that is as good as one can get); apart from the engine (there again not everyone makes their own ) , LPI and appropriate shaping of fuselage to reduce RCS below 0.0X m^2 all other areas are covered under the Tejas program so given our MIL industrial prowess and infra in this field it does not really hurt us if we are 10 years late because what we are doing is the hardest part . In fact I would say more than the LPI and low RCS thingy we need to just get one more piece right i.e. the engine and then we would have truly arrived on the big table.

[vic]

Does reference to emitter in LCA electronic warfare suite mean DIRCM?

[Karan M]

I always thought that EW was an integral part of Tejas program. Now there is this news that no plane as ever flown with it This gives already reluctant IAF a huge stick to beat this program. Not saying that IAF wasn't aware of it.

Are these guys so unsure of their own capabilities or am I missing something about how planes are designed ? If plane crash was an issue, then how they'll fit the system on to later LSP models after testing it on the one which has been grounded for 8 frigging years ?
Something is really effed up

You are mixing up things. EW in the LCA program was via the 8th pylon - "special pylon", which is where an external EW pod would be carried. Now, they are moving the EW system internal, which is always a challenge with a tightly packed design like the LCA. As matter of fact, even the Su-30 MKI cannot fit in an internal EW suite and can carry only wingtip mounted pods.

As regards the plane crashing stuff - thats a bit of hyperbole from the journalist. If you put in a powerful EW system within an aircraft, obviously there will be EMI/EMC concerns. But India does have the facilities and technical acumen to check this out. It would be more a case of don't gild the lily - i.e. dont focus on putting in an internal EW suite until and unless the customer asks for it, and sufficient engineering resources are available after more critical requirements have been met.