LCA: News & Discussions - October 2016

[Gyan]

Let's post positive suggestions on how to accelerate induction of LCA. ESPECIALLY MK-1A

[nirav]

Gyan ji, hope the LCA flies half the MKI hours ... its still a win at 30 hours per year right ?

[tsarkar]

The stencilling looks phoren and the 1" x 1" is suspicious. Indian Stds are SI units - not imperial units

There is a Patent Number stenciled too that takes away any hopes of Chinese style reverse engineering.
This is the famous UK Chemring dispenser that is made in Nagpur
http://www.defencenews.in/article/Made- ... tain!-2690

[GShankar]

@JayS, I saw your post. Asked the query, will update once I hear something back.

[tsarkar]

What is the total number 123 or 103 or 83? (Not counting till lsp)

20 Mk1 IOC ordered 2006
20 Mk 1 FOC ordered 2010 - delivery until 2020
83 Mk1A as per SOP 2018 ordered 2016 for delivery from 2020-2026
Mk2 will be produced from 2026 onwards.
Mk 2 will be developed and productionized from 2018-2026, which is a very reasonable 8 years.

Total 123 which is equal to the peak size of Jaguar fleet in IAF service.

There are sufficient orders - 20 IOC + 20 FOC + 80 Mk1A - to fine tune production.

I have my doubts about LCA orders. It has "intent" for 120 for sure, but it has firm orders of only 40, is what I believed until now. Recently Tejas FB page Admin stated that there are in fact only 20 orders placed so far.

From GoI itself http://pib.nic.in/newsite/PrintRelease. ... lid=146717

As of now, IAF has placed order in 2006 for 20 Tejas aircraft in IOC configuration and another 20 aircraft in FOC configuration in 2010.

PS - To realistically set expectations before someone starts crying on "delayed" delivery of Mk1A to SOP 2018 standards, then kindly note that as per plan production of Mk1A will start from 2020 and go until 2026, a good four+ years from today.

[tsarkar]

http://indiatoday.intoday.in/story/manh ... html48,000 crores / 83 = Rs 578 Crores per plane. = $88 million per plane. Something doesnt add up.

X/Y is not the right calculation.

Typically proposal notes in GoI also contain 1. Infrastructure (or modifications to infrastructure). In Naval Terms that may include extending jetties for large ships like Vikramaditya or Jalashwa or increased depth and frequency of dredging the seabed 2. Fast moving spares 3. Ground Handling Equipment 4. Weapons & Stores like jettisonable EFT 5. Staffing costs for new units - that over & above salary and housing might include a KV school for kids of personnel or a small market for groceries & FMCG in the residential area

Since we do not know what is included and what is not, X/Y wont give the accurate figure.

PS - What we know is that simulators are included in the approved funding

[tsarkar]

Anyways there is another thing I am scared to put up here, because if some IAF brouchure reading types come across it, it will mean another change in the current MK1 !

You certainly have high airs about yourself. The IAF folks have much better things to do than read your or my posts.

The IAF - like any operational organization - wants proven mature technology - like the Dassault Analogue FBW system for Tejas to simplify development cycle. However, ADA went for Digital FBW system.

http://www.thehindu.com/thehindu/2003/0 ... 811200.htm

The decision to adopt a digital FBW system added considerably to the development process. This was only partly accounted for (perhaps by about 18 months) by the curtailment of Lockheed Martin's critical assistance. To lament that if Dassault's offer of an analogue system in 1988 had been accepted the flight test programme could easily have been completed by now will be to cry over spilt milk. On the other hand, the LCA's quadruplex digital FBW system is what the world's most advanced aircraft currently use and an analogue system may already have been a prime target for replacement. By way of analogy, the F-16 replaced analogue with digital controls while morphing from its original A/B form to the much more capable F-16 C/D in the 1990s.

When I had earlier pointed this out to you, you then ranted that IAF is a dinosaur not supporting development of cutting edge technology like Digital FBW system. And now you do an about turn speculating IAF will demand More Electric Architecture to delay Tejas.

You at that point of time also posted giving example of P&W Geared Turbo Fan and how Airlines are supporting development of new technology by ordering P&W GTF for Airbus 320 neo. However, with the shaft bending/flexing issues, airlines including Qatar & Indigo have refused to take delivery, proving operational organizations prefer stability over cutting edge technology.

So make up your mind where you stand - on one hand you curse IAF for choosing the stable but analogue Dassault FBW system and on the other hand you curse IAF by speculating it might specify new and unproven technology like More Electric Architecture.

FWIW, its developers like ADA who pitch for new technology - like digital FBW system for Tejas.

And ADA has gone beyond More Electric Architecture to Electro Optic Architecture! Refer here
http://aviationweek.com/defense/new-des ... t-aircraft

A brief list of the ambitious technologies that India’s Aeronautical Development Agency (ADA) hopes to equip the AMCA with includes a panoramic active matrix cockpit, triplex fly-by-light electro-optic architecture, serpentine air intakes to suppress radar signature and an optic-fiber-based digital flight control computer

Now, fly by light is an extremely nascent technology that even F-35 doesnt use and few experimental aircraft like a NASA F-18, Gulfstream 550 and Eurocopter EC135 tried as per this 2014 research paper here https://etd.ohiolink.edu/!etd.send_file ... ion=inline

Despite its low stage of maturity anywhere in the world, ADA has put it as a AMCA feature to be developed. No prizes for guessing the risk and time it would take to make this technology operationally stable.

So please be honest, Vina, and in light of the fact that digital FBW took time to develop, among other things, STOP BLAMING IAF for delays it had nothing to do with! Its like blaming Indigo and Qatar Airways for delay in A320 neo entering service!

[JayS]

What is the total number 123 or 103 or 83? (Not counting till lsp)

20 Mk1 IOC ordered 2006
20 Mk 1 FOC ordered 2010 - delivery until 2020
83 Mk1A as per SOP 2018 ordered 2016 for delivery from 2020-2026
Mk2 will be produced from 2026 onwards.
Mk 2 will be developed and productionized from 2018-2026, which is a very reasonable 8 years.

Total 123 which is equal to the peak size of Jaguar fleet in IAF service.

I have my doubts about LCA orders. It has "intent" for 120 for sure, but it has firm orders of only 40, is what I believed until now. Recently Tejas FB page Admin stated that there are in fact only 20 orders placed so far.

From GoI itself http://pib.nic.in/newsite/PrintRelease. ... lid=146717

As of now, IAF has placed order in 2006 for 20 Tejas aircraft in IOC configuration and another 20 aircraft in FOC configuration in 2010.

PS - To realistically set expectations before someone starts crying on "delayed" delivery of Mk1A to SOP 2018 standards, then kindly note that as per plan production of Mk1A will start from 2020 and go until 2026, a good four+ years from today.

I corrected myself to 40 orders in one of the later posts somewhere. Its just FB page admin had said 20, so I had second thoughts.

Just nit-picking in bolded part, the contract not sighed still, is it? DAC approval doesn't mean contract for orders signed, just proposal to buy cleared. Yet to get clearance from CCS.

[tsarkar]

^^ Yes Sir, since DAC is chaired by RM (Raksha Mantri) and CCS is chaired by PM where RM proposes, unless things are really wrong, like national financial crisis, it usually gets CCS approval.

[JayS]

^^ Yes Sir, since DAC is chaired by RM (Raksha Mantri) and CCS is chaired by PM where RM proposes, unless things are really wrong, like national financial crisis, it usually gets CCS approval.

M not worried it will get stuck. Ball in ADA/HAL's court firmly for MK1A now.

[shiv]

Here is what AM (retd) Rajkumar wrote about the CLAW development for Tejas

[tsarkar]

As I quoted Dr. Tamilmani, mid air refueling was added because work was done on Mirage 2000, Jaguar, AEW&C (that was never designed for A2A refuelling by Embraer) and ADA was confident on being able to do it in a short timeframe.

Already replied about having it designed in, vs squeezing in something later. Jag an M2k were already plumbed for mid air refueling. AEW&C is anyways a custom modification from the stock airframe. Not too difficult to add that into such a large airframe. Totally different case with the Tejas.

So you think IFR was a late IAF requirement, and that is delaying induction. Refer the following images


That is a mockup from an Aero India in late 90’s early 2000’s. Most likely Aero India 1998. It shows Inert/Live Matra BGL, Sea Eagle, Super 530D and Matra Magic II. All those weapons were current then and obsolete now. Those weapons certify the vintage of the event when the photo was taken. Guess what? Tejas has IFR probe


This is one of the oldest Tejas images around for 20+ years. Old timers will remember. It refers to MMR & GTX Kaveri. Guess what? It shows IFR probe


This is dated 2002. And it has IFR probe.

Tejas always had internal plumbing for IFR.

And going by your twisted logic, its less time consuming to add IFR plumbing to Embraer AEW&C but very time consuming to add IFR to Tejas.

And following are CAG reasons for delay in IOC

http://cag.gov.in/sites/default/files/a ... 7_2015.pdf

Page 51

The reasons pointed out in the EC meetings were mainly delay in snags analysis, slow recovery of aircraft from rectification, shortage of critical LRUs at flight hangar, aircraft being used as test rigs, large number of unproductive sorties2, production quality issues affecting flight safety, nonavailability of aircraft in the correct SOP.

Though to be fair, snag analysis takes time. If one knows what is wrong, there would be no snag in the first place?

And those who think IAF ASR was unobtanium, please consider this Page 50

Thus, in the absence of FTS, technical life of LCA could not be determined
and ADA/HAL had to obtain concession at the time of IOC (December 2013)
from Air HQ which limited the life of airframe to 1000 hours as against the
ASR specification of more than 3000 hours.

Technical Life of MiG-21Bis – 2400 Hours
source http://www.bharat-rakshak.com/IAF/Aircr ... Bison.html

Technical Life of Jaguar IS/IM– 3000 Hours
Technical Life of Jaguar IB – 6000 Hours
source http://www.acig.info/CMS/index.php?opti ... 3&Itemid=1

Technical Life of F-16 – 8000 Hours
Source https://www.flightglobal.com/news/artic ... me-375914/

So was IAF ASR specification of 3000 hours for Tejas unreasonable? No, its in MiG-21/Jaguar range and nowhere close to F-16.

And IAF gave a waiver of airframe life of 1000 hours.

That @200 hours a year is just 5 years.

Hope this dispels the notion of IAF ASR being unreasonable and unrealistic.

And the waiver dispels notion of IAF not being supportive

Let me also point out a few things more than Arup Raha Harrumphed about recently as "improvements "

Asked for provision of growth for AESA. Asked for higher fuel load and range, asked for airborne refuelling,asked for IR tracker, asked for internal SPJ (they had already done the Bison upgrade by then, they knew that an SPJ was needed), asked for higher thrust engine. IF they had done that at the start of FSED phase, the LCA that would have come out would have the mould line of the proposed MKII right from the beginning and NOT the current Mk1 version! There would have been a fuselage stretch for extra room for equipment and fuel, aero refinements to match that ask and you could have fielded a version with a normal radar like the MK1 but with an airframe that incorporated the stuff you wanted , you have got a right sized airframe and not come and Harrumph and try to derail the program at the last minute saying oh, I want an INTERNAL SPJ! Where the hell were you guys at FSED stage , when the plane is basically getting re-engineered?

Your harrumphing is complete fiction and dishonest.

Nowhere has ACM Raha said these things.

IR Tracker was never ever there, whether in original ASR or in Mk2 specifications. And like I mentioned earlier, because Litening has superior FPA and hence better resolution than Russian OLS, IAF including Sukhoi pilots use it for A2A. And based on IAF experience, the Israelis are introducing new A2A modes in Litening.

Why cant people simply accept that everyone worked in best interests and it took the time it needed.

[vina]

The IAF - like any operational organization - wants proven mature technology - like the Dassault Analogue FBW system for Tejas to simplify development cycle. However, ADA went for Digital FBW system.

You want to troll, well, I can troll too. So let me do so by highlighting exactly the same article you posted with a different emphasis.

http://www.thehindu.com/thehindu/2003/0 ... 811200.htm
The decision to adopt a digital FBW system added considerably to the development process. This was only partly accounted for (perhaps by about 18 months) by the curtailment of Lockheed Martin's critical assistance. To lament that if Dassault's offer of an analogue system in 1988 had been accepted the flight test programme could easily have been completed by now will be to cry over spilt milk. On the other hand, the LCA's quadruplex digital FBW system is what the world's most advanced aircraft currently use and an analogue system may already have been a prime target for replacement. By way of analogy, the F-16 replaced analogue with digital controls while morphing from its original A/B form to the much more capable F-16 C/D in the 1990s.[/b/]

When I had earlier pointed this out to you, you then ranted that IAF is a dinosaur not supporting development of cutting edge technology like Digital FBW system. And now you do an about turn speculating IAF will demand More Electric Architecture to delay Tejas.

Rewritten as..

As I pointed to you earlier, IAF insists on being stuck in an age of a technology dinosaur and insists on reinvent an already obsolete system, which is not directly applicable from the M2K to the LCA (even if we got it from Dassault, who were not willing to do the development of the digital system with us as they preserved it as "crown jewels" for in development Rafale) a system that would be incredibly hard to modify and maintain and radically different from the skill base of the world that went fully digital across industries in the late 70s and early 80s .

Atleast please understand what you are writing before pulling out random stuff and posting. The FCS was a critical factor, the timeline was baked into the project plan, the nuke tests delayed it etc. But that has NOT been the key reason for delays. The FCS along with the composites have been a smashing success and it is the primary reason why you are able to field a plane comparable to the Gripen C/D (tech level of F16 BLK 52 or better ) TODAY and not an oboselete black box from the M2K analog system and if you need to reprogram the control laws in that for any reason, GOD save you. That skill would be SO rare to find and indeed terribly difficult to do.

[vina]

FWIW, its developers like ADA who pitch for new technology - like digital FBW system for Tejas.

And ADA has gone beyond More Electric Architecture to Electro Optic Architecture! Refer here
http://aviationweek.com/defense/new-des ... t-aircraft

You do realise that what they are talking about is replacing the data bus with an optic bus , instead of the usual electric bus ? That has Nothing to do with the elctro hydrostatic actuators. The only thing is that the signalling to the actuator will be via optical means and indeed, the actuator itself can be the hydraulic kind that we have at present or the "more electric" ones that are in use in F35 and A380!

[nirav]

From what I remember of Sh. Arup Raha's press conference post the declaration for Mk1A, he said the IAF will take as many LCAs as HAL can give(manufacture). Wasnt any 'harrumphing' whatsoever then nor in his test flight of the LCA when the man was simply beaming post the flight !

a start has been made with the 20+20+83. Need to see how quickly HAL can get the birds off its line.

[tsarkar]

^^ No one is denying that despite the high risk, the Digital FBW turned out OK, and despite LM & Dassault doing it the same time. And hopefully the flight envelope of Tejas to max AoA will be achieved before FOC.

And Mirage-2000 and F-16A/Bs are flying quite well with analogue FCS around the world, with Greek Mirage 2000 with analogue FBW shooting down Turkish F-16s with analogue FBW with MLUs upgrading them to digital systems, so no one, including Pakistanis buying third hand F-16s are stuck anywhere.

The ability of a Tejas/Mirage 2000/F-16 to pitch or turn is limited by the ability of its actuators, and not the databus or flight control computer. So while digital is more reliable than analogue, it doesn't give the ability to pitch or turn better since the actuators are the same. So for an IAF or PAF, the technical superiority of one against the other doesn't matter. Which is why Pakistan is buying third hand F-16A/B with analogue systems over possibly digital J-10 / JF-17

Which is also why Qatar or Indigo are not taking delivery of A320 Neo. They need an engine that can move passengers cheaper and if possible over longer ranges. If geared turbofan is not able to do it cheaply or reliably, then they give damm about the technology. Typically on taking delivery they're obliged to pay, so they're not taking delivery and the planes are lined up at Airbus factory.

And given that full Tejas flight envelope hasn't still been opened up (AoA remaining as Dr Tamilmani said), it probably wasn't worth the investment of time.

Operational organisations like IAF, Indigo, Qatar Airways, PAF give a damm to technology unless it delivers significant (business) outcomes.

What is dishonest is your blaming the time taken to develop it as well as the resultant flight testing duration - that is still not completed - on fictitious IAF requirements.

What is extremely offensive is your pomposity -

Anyways there is another thing I am scared to put up here, because if some IAF brouchure reading types come across it, it will mean another change in the current MK1 !

As is your complete utter dishonesty in attributing false statements to ACM Raha

Let me also point out a few things more than Arup Raha Harrumphed about recently as "improvements "

Asked for provision of growth for AESA. Asked for higher fuel load and range, asked for airborne refuelling,asked for IR tracker, asked for internal SPJ (they had already done the Bison upgrade by then, they knew that an SPJ was needed), asked for higher thrust engine. IF they had done that at the start of FSED phase, the LCA that would have come out would have the mould line of the proposed MKII right from the beginning and NOT the current Mk1 version! There would have been a fuselage stretch for extra room for equipment and fuel, aero refinements to match that ask and you could have fielded a version with a normal radar like the MK1 but with an airframe that incorporated the stuff you wanted , you have got a right sized airframe and not come and Harrumph and try to derail the program at the last minute saying oh, I want an INTERNAL SPJ! Where the hell were you guys at FSED stage , when the plane is basically getting re-engineered?

[vina]

As is your complete utter dishonesty in attributing false statements to ACM Raha

Reading comprehension problems ? Can you re-read what I wrote?

[shiv]

That is a mockup from an Aero India in late 90’s early 2000’s. Most likely Aero India 1998.

This was Avia India 1993 - the first ever show

[Indranil]

tsarkar sahab and vina, You both are on the edge. Let's tone it down.

tsarkar sahib, you are right. Not all delays can be ascribed to IAF. But some can be. For example Cmde Mao is a very practical man. He just wants to use Harrier's Derby adapters on the Tejas. IAF wants custom designs. These spread a already strained team even thinner.

During Rajkumar sahab, Atre sahab, and Hariharan sahab, ADA did really really well. ADA did chose to go with contemporary technologies of the late 1990s, underestimated the challenge, and therefore promised unrealistic timelines. But did they take more time than required, I differ vehemently on that with you. I am student of development of the aircrafts around the world. I think the bunch at ADA did a stellar job considering what they had at their disposal. They kind of pulled together a miracle like WWII western design bureaus.

However, I have not been a big fan of the LCA management in the last 5-7 years. Before this time it was a bunch of scientists chasing a crazy dream. Now, it's a fragmented team going through its jobs. Heads of those teams delay or accelerate progress for best timings to get maximum recognition. May be we can talk over chai some day.

But here are some encouraging facts:
1. The complete envelop of the aircraft has been opened. The expansion of envelop to 26+ degrees is beyond what was originally envisioned as the slow speed handling of the aircraft is better than expected. At 24 degrees AoA, the minimum speed of LCA is just over 200 knots. That is why you saw those commentators go oohs-and-aahs when Tejas demonstrated its shortest radius turns. If they go to 26 degrees, the slowest speed is going be below 200 knots. That's turboprop territory.
2. IAF is extremely happy with Tejas's takeoff, landing, subsonic agility and maneuvering capabilities. IAF has complaints about its maintainability which is being addressed in the 1As.
3. IAF has set clear priorities: They want BVR firing (guided by the MMR) and IFR probe first (will be completed next month). Gun-firing is next. It will happen next year. They don't expect anything to go wrong. It worked well on ground. it should be smoother in the air.

P.S. The limits of the envelop are dictated by the control authority of the surfaces, not the actuators themselves.

[Pratyush]

Now that my major peeve is taken care of and we have the ACM on record that the IAF will take as many as can be produced. I call on the MOD to insure that HAL deliver enough LCA to meet up with the IAF s requirements in terms of replacement of 21 & 27, in the given time frames.

Please make it happen.

[JayS]

@JayS, I saw your post. Asked the query, will update once I hear something back.

OK. Thanks.

[JayS]

During Rajkumar sahab, Atre sahab, and Hariharan sahab, ADA did really really well. ADA did chose to go with contemporary technologies of the late 1990s, underestimated the challenge, and therefore promised unrealistic timelines. But did they take more time than required, I differ vehemently on that with you. I am student of development of the aircrafts around the world. I think the bunch at ADA did a stellar job considering what they had at their disposal. They kind of pulled together a miracle like WWII western design bureaus.

The first proposal itself was rather stupid. In 1985 ASQR were issues and induction in 1994 was envisioned. Even with 3rd gen metal bird with manual control 9 years was too less time for design from scratch. Who did that was a different question. But I would say all stakeholders were equally clueless about the development efforts.

[rohitvats]

The first proposal itself was rather stupid. In 1985 ASQR were issues and induction in 1994 was envisioned. Even with 3rd gen metal bird with manual control 9 years was too less time for design from scratch. Who did that was a different question. But I would say all stakeholders were equally clueless about the development efforts.

Sorry, but it is important to pin-point problems created by each stakeholder to ensure that the same are not repeated during the next project.

It was the R&D establishment which got carried away by wanting to design and develop everything in-house. And greatly under-estimated the challenges. Something which came to bite-us in the back.

IAF had objected to most of the proposal - from technologies being sought to be developed to the timeline projected. It seems no-one in the R&D establishment was bothered about the impact of delays on the operational preparedness of the IAF. The weapon system and the MIC is means to an end - not an end in itself.

It is fashionable on BRF to use the term 'iterative development' - but it is used very selectively. Whenever a delay in IOC or FOC is attributed to the a/c not able to meet a particular requirement, out comes the argument about iterative development. Of how IAF should accept the fighter as it is while more capabilities are added in later-on. But the moment you turn around this argument and question the R&D establishment's decision to development cutting edge technologies de novo and its serious impact on timeline, we've arguments about catching up on technology and all that. And we've the same mistakes being repeated again.

[Pratyush]

Rohit, in the same light, we can also say that non development of marut follow ups put us in a position where everything had to be developed in house again. For LCA. The object now should be to make sure that the lessons learned are retained and are not abandoned in favour of an easy solution.


To everyone I say let's focus on the future of the program as the issues that plagued this program have been overcome to a large extant.

Let's figure out how the IAF can make it the mainstay of the fleet and how it can be done by 2025.

[tsarkar]

But some can be. For example Cmde Mao is a very practical man. He just wants to use Harrier's Derby adapters on the Tejas. IAF wants custom designs. These spread a already strained team even thinner.

Indranil, I'm not aware of any pylon adaptor issue, so would request you to amplify.

Also, Commodore Mao is heading NFTC (National Flight Testing Center), so his job profile is flight testing systems, not identifying which systems to use, that would be the job of Commodore Balaji & team.

ADA did chose to go with contemporary technologies of the late 1990s, underestimated the challenge, and therefore promised unrealistic timelines. But did they take more time than required, I differ vehemently on that with you. I am student of development of the aircrafts around the world. I think the bunch at ADA did a stellar job considering what they had at their disposal. They kind of pulled together a miracle like WWII western design bureaus.

No denying that.

But programs require time-benefit analysis. A start from scratch program will take time. Reusing existing technology saves time.

Its a choice program management need to make.

However myths needs dispelling - like IAF insisted digital FBW. No it didnt.

Other myth perpetrated here was that analogue FBW lacked capability like separate regimes for A2A or A2G and that pilot had to constantly monitor his flight envelope.

To dispel that myth, I posted test pilot report of Mirage 2000 FCS system http://www.icas.org/ICAS_ARCHIVE/ICAS19 ... -4.5.1.pdf Page 5

...the pilot selects a "COMBAT" or "HEAVY LOADS" configuration on a switch which connects such gains so as to limit the aircraft load factor to a set value...

Digital FBW systems anywhere didn't add any tranformational capability over analogue systems, what they added was much improved reliability, maintainability and incremental capability.

Take the example of P&W GTF with shaft flexing/bending issues on A320 neo that not one airline is taking delivery of. One workaround was running the engine on ground for a few minutes. However, given steep airport fees and the need of airport & airlines to accommodate maximum amount of flights per day, airlines are not accepting that workaround.

Yet no one is blaming airlines for 1. unachievable requirements or 2. being dinosaurs not promoting technical development by refusing to accept A320 neo.

P.S. The limits of the envelop are dictated by the control authority of the surfaces, not the actuators themselves.

The ability of a Tejas/Mirage 2000/F-16 to pitch or turn is limited by the ability of its actuators, and not the databus or flight control computer. So while digital is more reliable than analogue, it doesn't give the ability to pitch or turn better since the actuators are the same.

Let me quote a practical example here.

The computer may compute very precise instructions for the actuator based on data crunched from air data sensors, altimeter and pilot inputs.

The quad redundant network may send the instruction onward and the feedback backward very fast and efficiently.

However, if the actuator can move only 2 degrees a millisecond, and if instructions are like 5 instructions a millisecond, then the actuator cannot execute the instructions fast enough. (both numbers hypothetical)

Two things can happen depending on how the system was designed - a backlog of instructions will build up for the actuator. If the actuator executes one action after other, it will lag actual situation, which has potentially negative consequences.

Alternately, the actuator may start skipping instructions, that too has potentially negative consequences.

I actually faced this problem in real life. I work for a large corporation and my customers are large enterprises. One of them complained that my industrial automation solution (one of the best of breed in industry) is not managing the systems right. We put our best R&D engineers at work and after a lot of effort discovered that more than one instruction/microsecond caused the system to skip the subsequent instruction(s), and there needs to be a gap of one microsecond between instructions for the system to execute it.

Which is why aircraft FCS are designed around the capacity of the actuator to execute the instruction. That is the limiting factor, and not the capacity of computer to generate instructions and the capacity of databus to carry instruction/feedback rapidly.

Hope that explains

[JayS]

The first proposal itself was rather stupid. In 1985 ASQR were issues and induction in 1994 was envisioned. Even with 3rd gen metal bird with manual control 9 years was too less time for design from scratch. Who did that was a different question. But I would say all stakeholders were equally clueless about the development efforts.

Sorry, but it is important to pin-point problems created by each stakeholder to ensure that the same are not repeated during the next project.

It was the R&D establishment which got carried away by wanting to design and develop everything in-house. And greatly under-estimated the challenges. Something which came to bite-us in the back.

IAF had objected to most of the proposal - from technologies being sought to be developed to the timeline projected. It seems no-one in the R&D establishment was bothered about the impact of delays on the operational preparedness of the IAF. The weapon system and the MIC is means to an end - not an end in itself.

It is fashionable on BRF to use the term 'iterative development' - but it is used very selectively. Whenever a delay in IOC or FOC is attributed to the a/c not able to meet a particular requirement, out comes the argument about iterative development. Of how IAF should accept the fighter as it is while more capabilities are added in later-on. But the moment you turn around this argument and question the R&D establishment's decision to development cutting edge technologies de novo and its serious impact on timeline, we've arguments about catching up on technology and all that. And we've the same mistakes being repeated again.

Sure its important to do root cause analysis. But there is limited factual data available, so it goes into hypotheses and conjuncture regime for most. I, personally would not want to blame either IAF or R&D establishment without proper info. In fact I have never argued much on LCA project from this period. I have always argued regarding things post 2001. So I keep away from these discussions. Others are free to engage and I would be all ears. So I evaded that part saying its a different question.

I have always wondered why the 9yr time frame was put in first place. I can make hypotheses based on some assumptions (such as they expected far more help from US that what actually was received) but I don't think its worth putting here.

Iteration based development is somewhat different thing. If IAF had given certain ASRs, should those be achieved in one shot or in stages - that is iterative development. Every other AF accept home-grown aircrafts in tranches. This is not a outlandish expectation. But yes, the plan has to be on table right from start and not an afterthought at 11th hour.

Agree on repeating same mistakes. We should have started parallel technology programs for AMCA post 2001. We have done zilch. Now AMCA will have issues with technology maturity. Even now a separate tech demo of LO LCA could be launched, but there is no funding even for argent programs. The blame squarely lies with GOI which neither had a vision nor will to fund such programs. Even today RnD funding is peanuts.

[JayS]

Other myth perpetrated here was that analogue FBW lacked capability like separate regimes for A2A or A2G and that pilot had to constantly monitor his flight envelope.

To dispel that myth, I posted test pilot report of Mirage 2000 FCS system http://www.icas.org/ICAS_ARCHIVE/ICAS19 ... -4.5.1.pdf Page 5

...the pilot selects a "COMBAT" or "HEAVY LOADS" configuration on a switch which connects such gains so as to limit the aircraft load factor to a set value...

Digital FBW systems anywhere didn't add any tranformational capability over analogue systems, what they added was much improved reliability, maintainability and incremental capability.

But that discussion was regarding Swing-role, whether swing-role and multi-role are same things or not. And it was never "digital vs Analogue". I do not remember anyone raising that point from that discussion.

Though I agree that whether M2K had digital or analogue it would not have changed its capabilities by any significant amount.

Take the example of P&W GTF with shaft flexing/bending issues on A320 neo that not one airline is taking delivery of. One workaround was running the engine on ground for a few minutes. However, given steep airport fees and the need of airport & airlines to accommodate maximum amount of flights per day, airlines are not accepting that workaround.

Yet no one is blaming airlines for 1. unachievable requirements or 2. being dinosaurs not promoting technical development by refusing to accept A320 neo.

Actually Airliners don't gives two hoots to technology. All they care is how much is SFC and DOC. For them whoever gives lesser number, they go there. No one expects them to support tech development or anything like that. But an AF is not in the same league. World over all AFs accept aircrafts in limited capabilities in tranches and they are far more involved into the design process and tech development. I have never seen any airline funding a technology development project so far. But AFs do. IAF better have an institutional capability in design/development of aircraft systems. In their own reply to CAG over why they were not involved in LCA project before 2006, they said our expertise is in operationalizing and using a platform, not designing. This will not take them too far if they want to own design project a la USAF. IMO they should go for it.

The ability of a Tejas/Mirage 2000/F-16 to pitch or turn is limited by the ability of its actuators, and not the databus or flight control computer. So while digital is more reliable than analogue, it doesn't give the ability to pitch or turn better since the actuators are the same

Which is why aircraft FCS are designed around the capacity of the actuator to execute the instruction. That is the limiting factor, and not the capacity of computer to generate instructions and the capacity of databus to carry instruction/feedback rapidly.

Hope that explains

Whereas in principle you are right, what IR said is also correct. The envelop is *mainly* defined by the maximum forces the control surfaces can provide, not really the rate by which you can deploy control surfaces. So just having faster actuator will not increase AoA for example. But in some cases having a faster actuator could help in dealing with certain instabilities, but generally those happen in transonic regimes which fall in the middle of the envelop. So in a traditional sense it does not affect the envelop, but if you consider roll rate or pitch rate vs Mach number as an envelop then actuator could come into picture. Note, "could" since one must also consider how the aircraft responds to the given input. If the aircraft response is slower than your actuation rate then of coarse actuators will not be the bottleneck - and this is the case in most of the envelop points. IMO, actuation speed is less of an importance than flight control capabilities while envelop is fixed. However in certain cases limit on actuation speed could make some configurations impractical. But this will be resolved in conceptual design itself.

[geeth]

The blame squarely lies with GOI which neither had a vision nor will to fund such programs. Even today RnD funding is peanuts.

THAT in jist is the reason for majority of problems caaried on from Nehru era. Mo institutional build up, allocating funds for sustaining what is already built on, setting up world class institutions and R&D facilities, entrusting responsibility in the hands of talented people instead of psycophants, doind the right things to retain talent, inculcating a sense of pride in desi products, curbing the extra territorial authority of babus, allocating sufficient funds AND giving freedom to scientific community to spend that money, employing 'go getters' to steal technology ....the list is long. It is not the actuator or canopy or engine or the designers behind it who are at fault. It is the lack of a 'mai baap' in most of the institutions that is making them mostly inefficient. There was a glimmer of hope when Kalam was around. He started many things, even if they were ambitious. But there were many others including Jaichands who were putting a lot of hurdles. With the right kind of support from necessary quarters and curbing of activities of non-interested parties, things will mprove. It has to.

[vina]

Other myth perpetrated here was that analogue FBW lacked capability like separate regimes for A2A or A2G and that pilot had to constantly monitor his flight envelope.

Classic "myth" building. Both the F16 A/B and M2K had /have "carefree" handling, and the pilot doesnt need to monitor envelope in whichever mode. No one posted otherwise.

Digital FBW systems anywhere didn't add any tranformational capability over analogue systems, what they added was much improved reliability, maintainability and incremental capability.

Anyone who knows anything about programming / computers/electronics will tell you that programming and building a digital system is FAR easier than an analog system and that extends to maintenance. You CANNOT take the FCS from the M2K and pop it into the LCA without changes. Each plane has a custom programmed FCS. It would have still needed entire reporgramming (at analog level, sorry, no writing ADA/whatever code, compiling and executing and testing out on a simulator and doing debugging. No sir. You are far better off doing it in digital and that is what they did and by the time the LCA was on the drawing board, the entire electronics industry had moved to digital. Contrary to what you surmise, digital is ACTUALLY easier and less painstaking and easier to do , rather than re-invent the wheel and it is not a rip from M2K and drop into LCA for analog either.

Actually Airliners don't gives two hoots to technology. All they care is how much is SFC and DOC. For them whoever gives lesser number, they go there. No one expects them to support tech development or anything like that.

Oh. Absolutely wrong. The major airlines are deeply involved in development with major manufacturers. No manufacturer builds anything without strong feedback loops and close working with major airlines. Things like range, fuel burn, MTOW , landing wts, cargo, capacity everything is done with airlines. If the B747 was developed with United as the lead, today, most planes are designed in consultation with major one like Singapore, ANA, Emirates , BA, Lufthansa etc. They sign up for the initial planes with the understanding that the first models rolling off the assembly lines might NOT meet the promised performance gurantees including fuel burn , range etc. Case in point, B 787 and Air India (AI got those at lower than usual prices becuase of the risk involved and also got compensation on performance shortfalls). See, the commercial world isn't stupid either when it comes to new planes. Sure if you are buying the 100 th plane that is rolling off the line, your risks are far lower, you end up paying a higher price and you get no extra guarantees on the performance as any shortfall would have been addressed. Any plane that doesnt meet the targeted performance fails in the market (MD11 for eg, could never meet it's fuel burn targets and was quickly moved out of passenger to cargo roles and MD itself got sold to Boeing).

Whereas in principle you are right, what IR said is also correct. The envelop is *mainly* defined by the maximum forces the control surfaces can provide, not really the rate by which you can deploy control surfaces. So just having faster actuator will not increase AoA for example. But in some cases having a faster actuator could help in dealing with certain instabilities, but generally those happen in transonic regimes which fall in the middle of the envelop. So in a traditional sense it does not affect the envelop, but if you consider roll rate or pitch rate vs Mach number as an envelop then actuator could come into picture. Note, "could" since one must also consider how the aircraft responds to the given input. If the aircraft response is slower than your actuation rate then of coarse actuators will not be the bottleneck - and this is the case in most of the envelop points. IMO, actuation speed is less of an importance than flight control capabilities while envelop is fixed. However in certain cases limit on actuation speed could make some configurations impractical. But this will be resolved in conceptual design itself.

We had an entire series of discussion with sampling rates and Nyquist limit and actuator freq etc and some pretty good posts by a couple of Electrical Engineers here. Take it from me. For an aircraft (within the design envelope), you will NEVER hit the actuator limit. It is a red herring. Why ? The actuator is actually just an active damping system. Now if you have actuator limitation, you would INCREASE the damping in the system so that it is well within the acutator limits.

In Inglees, what it means is that you would decrease the degree of instablity (ie, move the wing backwards towards the CG) and for a rocket you would increase the fin area (in the bottom) to make it more stable. This is a pure design choice, given the speed of the control system and the response rate. If you have a faster and more repsonsive one, you can decrease damping and make the vehicle more efficient (like American and Russian rockets in the cold war early stages. The americans had superior computers and controls and had more efficient rockets, Russian rockets were bigger and heavier.. the Russians retorted as if we were going to carry the rocket on our backs..)

[tsarkar]

But that discussion was regarding Swing-role, whether swing-role and multi-role are same things or not. And it was never "digital vs Analogue". I do not remember anyone raising that point from that discussion.

Swing role & multi role are all enabled by the flight control system. This was the discussion flow

How many of our fighters can be reconfigured mid-air for various roles like change from A2A role to A2G role like LCA can?? Anyone knows??

Probably none. What we have are "legacy" fighters that dont have the "control configured vehicle" features of the Tejas. The Jags and Mirages wont have them as wont the SU-30. They were simply not designed that way and our upgrades wont touch their FCS and critical flight controls that would remain a black box. You will have to push mechanical switches after they land to reconfigure them for the next mission.

The USP of Mirage 2000 was that it was IAF's first fighter with FBW. Vina was wrong that Mirage 2000 FBW lacked on-the-fly swing role capability when he wrote the above, as the Mirage 2000 FBW description indicates.

The analogue vs digital debate came when Vina called IAF a dinosaur and called the analogue FBW obsolete.

As I pointed to you earlier, IAF insists on being stuck in an age of a technology dinosaur and insists on reinvent an already obsolete system, which is not directly applicable from the M2K to the LCA (even if we got it from Dassault, who were not willing to do the development of the digital system with us as they preserved it as "crown jewels" for in development Rafale) a system that would be incredibly hard to modify and maintain and radically different from the skill base of the world that went fully digital across industries in the late 70s and early 80s .

While digital significantly improves reliability, it doesn't improve the pitch or turn rates over an analogue system.

And as for Vina's view of "incredibly hard to modify and maintain and radically different from the skill base of the world", guess what, HAL is modifying the Mirage 2000 with its own systems as shown here.



Guess its crystal clear who has reading comprehension problems.

[tsarkar]

M2K had /have "carefree" handling, and the pilot doesnt need to monitor envelope in whichever mode. No one posted otherwise.

Well, you yourself posted otherwise on Page 7 of this forum

What we have are "legacy" fighters that dont have the "control configured vehicle" features of the Tejas. The Jags and Mirages wont have them as wont the SU-30. They were simply not designed that way and our upgrades wont touch their FCS and critical flight controls that would remain a black box. You will have to push mechanical switches after they land to reconfigure them for the next mission.

http://www.icas.org/ICAS_ARCHIVE/ICAS19 ... -4.5.1.pdf Page 5

When the plane was fitted with heavy external loads, it became obvious that the pilot no longer "felt" these loads : the aircraft behaved as in clean configuration...

...Engineers in charge of structure stress analysis began to feel restless with fear that limit load would be often exceeded....


...the pilot selects a "COMBAT" or "HEAVY LOADS" configuration on a switch which connects such gains so as to limit the aircraft load factor to a set value...

[JayS]

Actually Airliners don't gives two hoots to technology. All they care is how much is SFC and DOC. For them whoever gives lesser number, they go there. No one expects them to support tech development or anything like that.

Oh. Absolutely wrong. The major airlines are deeply involved in development with major manufacturers. No manufacturer builds anything without strong feedback loops and close working with major airlines. Things like range, fuel burn, MTOW , landing wts, cargo, capacity everything is done with airlines. If the B747 was developed with United as the lead, today, most planes are designed in consultation with major one like Singapore, ANA, Emirates , BA, Lufthansa etc. They sign up for the initial planes with the understanding that the first models rolling off the assembly lines might NOT meet the promised performance gurantees including fuel burn , range etc. Case in point, B 787 and Air India (AI got those at lower than usual prices becuase of the risk involved and also got compensation on performance shortfalls). See, the commercial world isn't stupid either when it comes to new planes. Sure if you are buying the 100 th plane that is rolling off the line, your risks are far lower, you end up paying a higher price and you get no extra guarantees on the performance as any shortfall would have been addressed. Any plane that doesnt meet the targeted performance fails in the market (MD11 for eg, could never meet it's fuel burn targets and was quickly moved out of passenger to cargo roles and MD itself got sold to Boeing).

Range, payload, SFC, DOC - these are only Objectives or restrictions on design, and airlines do not care what technology it is being achieved with. Do you think Some airliners went with GTF because it technologically next logical thing?? No because it offers better economy over current two spool engines. GE had to commit +2% better economy to sell their LEAP engines and they are struggling there. They are working on their own GTF now, so is RR. Last time I checked no airline is funding this tech development programs for RR or GE. Putting money on performance and on technology are two different things. Also airliners get compensated for shortfalls or delays because there are contractual obligations. Like the above GE contract where they promised +2% over whatever GTF can do. If they can't achieve it they have to compensate Airliner for their loss. Agreed airliners take risks while ordering new aircraft, but then its because it gives them an edge over the competitors and the risk is well considered and its pure business. They don't put faith in new technology, rather they put faith in an OEM's ability to deliver on promised numbers. PW was working for 30yrs on GTF, ever heard any Airliner funding their research on GTF?? In fact all the commercial OEMs are heavily supported by governments for RnD apart from some of their own money.


If this is supporting technology development then IAF also does the same - give requirements and ask ADA/HAL to make it anyhow.

[vina]

Well, you yourself posted otherwise on Page 7 of this forum

what you are quoting out of context. What I wrote was about swing role /multi role / whatever you call it that it. This is not carefree handling within the envelope as defined by the config of the plane at that moment!

You seem to have a habit of mixing things up and quoting out of context. Again you are trolling here , so let me just respond by highlighting the "operative" part of what I wrote that you quoted .

What we have are "legacy" fighters that dont have the "control configured vehicle" features of the Tejas. The Jags and Mirages wont have them as wont the SU-30. They were simply not designed that way and our upgrades wont touch their FCS and critical flight controls that would remain a black box. You will have to push mechanical switches after they land to reconfigure them for the next mission.

http://www.icas.org/ICAS_ARCHIVE/ICAS19 ... -4.5.1.pdf Page 5

snip.....the pilot selects a "COMBAT" or "HEAVY LOADS" configuration on a switch which connects such gains so as to limit the aircraft load factor to a set value...

So where in any of this is anyone implying that the M2K is like the Mig29/Mig21 etc where the pilot has to keep a watch on the envelope or he will get into trouble ?

[vina]

Range, payload, SFC, DOC - these are only Objectives or restrictions on design, and airlines do not care what technology it is being achieved with.

Well, you have to be credible and show HOW your promise will be achieved and they will examine the risks and chances of success with that.

Do you think Some airliners went with GTF because it technologically next logical thing?? No because it offers better economy over current two spool engines.

They went with it because the physics support it, they would have seen demonstrator and plus the big name of P&W would have given them the confidence to risk their business on it. Note, here too, the airlines are taking a big risk on a radical technology jump. They too are supporting tech development and indeed in some cases putting their very EXISTENCE in line, even if the support is not directly with cash up front for R&D . But support they do, including inducting early bug ridden versions and supporting it through incremental development in the promise of preferential access and differential pricing later on when everything is fixed.

If this is supporting technology development then IAF also does the same - give requirements and ask ADA/HAL to make it anyhow.

IAF never seems to induct anything made locallyother than a fully baked product.. equivalent to buying the 100th sample rolling of the assembly line. That is what they do when they go abroad and import fighters . That some of them are half baked and bug ridden and needs significant efforts later on to support bring them upto scratch is a different story.

[Karan M]

Vina is right. That image supports his POV. To add capabilities to the Mirage 2000, HAL has to add its own mission computing system above the standard system. Next, this is mission avionics, not flight control which remains a black box for HAL. And the LCA digital system remains a generation ahead and is the basis for everything from Rustom to AURA.

[Indranil]

I don't know about Rustom Karan. But I agree with you. In hindsight, the digital FBW has turned out to be one of the best decisions taken. LCANavy, Mk1A, Mk2, AMCA, Aura, nothing would be possible without it.

[Kartik]

And those who think IAF ASR was unobtanium, please consider this Page 50

Thus, in the absence of FTS, technical life of LCA could not be determined
and ADA/HAL had to obtain concession at the time of IOC (December 2013)
from Air HQ which limited the life of airframe to 1000 hours as against the
ASR specification of more than 3000 hours.

Technical Life of MiG-21Bis – 2400 Hours
source http://www.bharat-rakshak.com/IAF/Aircr ... Bison.html

Technical Life of Jaguar IS/IM– 3000 Hours
Technical Life of Jaguar IB – 6000 Hours
source http://www.acig.info/CMS/index.php?opti ... 3&Itemid=1

Technical Life of F-16 – 8000 Hours
Source https://www.flightglobal.com/news/artic ... me-375914/

So was IAF ASR specification of 3000 hours for Tejas unreasonable? No, its in MiG-21/Jaguar range and nowhere close to F-16.

And IAF gave a waiver of airframe life of 1000 hours.

That @200 hours a year is just 5 years.

I hope you realise that the lack of a FTS is what restricts it to a sub-optimal 1000 hours. It is nowhere near the actual airframe limit. I've had a conversation once with a rather senior person who was among the first few that worked on composites in ADA on the LCA, and as per that gentleman, the intended fatigue life was much more than 3000 hours. He didn't go into a specific number, perhaps because he must've been aware that they hadn't yet tested it as yet.

But HAL has to get the FTS up and ready and must complete the fatigue testing before the first SP reaches 1000 hours. No more excuses. This is way too important.

[JayS]

I don't know about Rustom Karan. But I agree with you. In hindsight, the digital FBW has turned out to be one of the best decisions taken. LCANavy, Mk1A, Mk2, AMCA, Aura, nothing would be possible without it.

Not to forget RTD.

If they had gone for 3 channel digital + 1 channel analogue as per Dassualts suggestion, wouldn't ADA had to work more for every change. modifying both digital and analogue channels. Whereas now its all digital and arguably easier to deal with. The main reason for keeping analogue channel as back-up was less confidence on digital channels.

[Rishi Verma]

However, if the actuator can move only 2 degrees a millisecond, and if instructions are like 5 instructions a millisecond, then the actuator cannot execute the instructions fast enough. (both numbers hypothetical)

Two things can happen depending on how the system was designed - a backlog of instructions will build up for the actuator. If the actuator executes one action after other, it will lag actual situation, which has potentially negative consequences.

Alternately, the actuator may start skipping instructions, that too has potentially negative consequences.

I actually faced this problem in real life. I work for a large corporation and my customers are large enterprises. One of them complained that my industrial automation solution (one of the best of breed in industry) is not managing the systems right. We put our best R&D engineers at work and after a lot of effort discovered that more than one instruction/microsecond caused the system to skip the subsequent instruction(s), and there needs to be a gap of one microsecond between instructions for the system to execute it.

Which is why aircraft FCS are designed around the capacity of the actuator to execute the instruction. That is the limiting factor, and not the capacity of computer to generate instructions and the capacity of databus to carry instruction/feedback rapidly.

Hope that explains

Sir unfortunately it doesn't explain it.

You have a point to make but I must point out factually incorrect verbage. Fudging philosophy is ok, fudging engineering isn't.

1) flight control system is a classic pipelined feedback control system and none of two things you say will happen (instructions will keep getting "accumulated" or actuator will "skip")

2) simply put in a flight control system, there is an input (control command + pilot input), output (gain + actuator response), and feedback from sensors about aircraft status

3) based on the slowest responding unit (let's say actuators), the pipeline "ticks" are spaced (let's say every one second)

4) system stability depends on NEVER "accumulating" or "skipping" commands, system gain, and feedback attenuation.

5) system gain also is reduced if the actuator responds one or more ticks later, which is allowed

6) the other example at your work place where the micro was faster so skipping instructions has nothing to do with a pipelined control system

So the example you cited does not explain the point you were trying to make.

[Karan M]

I don't know about Rustom Karan. But I agree with you. In hindsight, the digital FBW has turned out to be one of the best decisions taken. LCANavy, Mk1A, Mk2, AMCA, Aura, nothing would be possible without it.

IR, LCA FBW is basis for all FVW designs by ADA and parallel orgs, is what I meant. The DFCC on LCA is also the basis for many more programs.

Unfortunately the mistaken belief is still being propagated that analog FBW was easier tban digital. In what sense? It would have taken a huge amount of testing to implement and IAF would be yelling from the rooftop about how LCA was obsolete before induction and non upgradeable. Plus as if Dassault would gave handed us the tech on a platter.