LCA News and Discussions

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Karan M
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Re: LCA News and Discussions

Postby Karan M » 23 Oct 2010 21:42

Kartik,

Superb find. Such motivated attacks on the LCA are not new. The last time around, it was so blatant that Domain-B had written a forthright article about the antics of these envelope experts. And this is one of the reasons, Indians should be very aware of these mischeif mongers, instead of bending over backwards awed by these "experts" command of mumbo-jumbo and attempts to selectively marshal data to claim anything and everything they want. As Goebbels said and now Shri Das are doing, "repeat a lie a hundred times and it becomes the truth".


Is it a co-incidence that this blatant attempt to shape opinion began when India ordered a higher power engine and firmed up plans to develop a world class LCA MK2, and when the program is picking up steam, Hardly.

As to how these worthies exploit the media..

http://www.domain-b.com/aero/20080218_duds01.html
.............
This compulsion to keep things under wraps can work against an organisation. It does, against the DRDO sometimes, because the DRDO is unable to rise to the bait and provide details to refute newspaper stories based on ignorance, bias or sheer motivation.

That these stories begin to fly around the time when a major aerospace or defence exhibition is held makes one wonder whether some of these reports are indeed motivated by a desire to please deep-pocketed global defence equipment companies that are desperate to sell their materiel to the Indian armed forces.

.......

A year ago, before the Aero India 2007 show in Bangalore in February, a series of articles referring to ''DRDO's duds'', run almost like a campaign, adorned the pages of a national daily, hammering the DRDO with some truths and some half-truths. This year, just before the DefExpo2008 in New Delhi, beginning 16 February, we see another attack on the DRDO for its supposedly miserable performance in developing the Light Combat Aircraft (LCA), the Tejas in another leading national daily.

A recent report in a leading national daily calls upon defence minister A K Antony to ''take a close look at the fighter which typifies all that is wrong with defence projects in India''. Then it proceeds to list ''all that is wrong with defence projects in India''.


"But that's not all. Intended or not, these campaigns end up drumming into our national psyche the stereotype of the inferior, shoddy, third-world DRDO versus technologically sophisticated Western aerospace companies."

.........

If India builds its own technology capabilities, who loses? It's the arms merchants of the world. So, come events like the DefExpo in New Delhi, they would love to have some mainline newspapers do some DRDO bashing. That can reinforce some myths about Indian R&D and help them sell some of their wares. But there is no reason we should fall for these ploys.

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Re: LCA News and Discussions

Postby Indranil » 23 Oct 2010 22:11

Neela wrote:Had the prof focused on just the delta wing part and the capabilities of the aircraft , it would have been received better. Instead the professor choses to be all over the place. And consider this : "If it is not a looker, it will probably not be a performer". Now what kind of argument is that?

Well Neela, "if it is not a looker, it will probably not be a performer" is a very valid statement for fighter jet design. By looker people mean a less draggy and clean airframe. He actually explains what he means by a looker if you read his article properly.
Neela wrote: Attributing the dorsal intakes to "inability" and "disinterest" - is that palatable? In the LCA video, P Subrahmanyam states the aircraft design and handling is exactly as the customer wanted.

I think you didn't understand what he was speaking of. He speaks of a Kfir like intake to be aesthetically more beautiful (and hence the comment "lack of interest"). If you were to be building your own plane. Would you now be very interested to make it look good in all aspects. He has no qualms about performance there.

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Re: LCA News and Discussions

Postby Austin » 23 Oct 2010 22:19

I think for a pilot and the way human mind perceives it "what looks good is good" , it reminds me of an interview of a test pilot involved in JSF program when he mentioned that Boeing JSF though was good but looked ugly and he did not get a good feeling looking at it compared to LM bird

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Re: LCA News and Discussions

Postby SaiK » 23 Oct 2010 22:26

Well, when it comes to role, it does not matter how it all started to be defined by scope, and slowly requirement changes creep up. This is all part of engineering and advancements. We can always switch role of "L" from light to lightening. What is more important is the concept of ensuring the capability of IAF for all its requirements and at the same maintaining our DRDO labs and HAL their maturity levels in dealing with staged and well planned changes.

It may appear in a ddm perspective that IAF keeps changing requirements. If they are doing so, then it should be a happier mood in DRDO labs since more work for them. They should focus on the deliverables.

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Re: LCA News and Discussions

Postby Vikram W » 23 Oct 2010 22:28

Critics are to engineers what dogs are to fire hydrants.

that said , we should remember that sometimes complaints and critics are our best form of feed back, especially if you have a very tight hierarchy full of yes men. LCA so far has been a glass half full ( The customer , IAF , has said it not me ) , and we should be able to learn from our mistakes rather than launch ad-hominem attacks on anyone who dare put a different opinion than ours.

yeah , go ahead firebomb me , but i'm just a sucker for free speech.

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Re: LCA News and Discussions

Postby Indranil » 23 Oct 2010 22:33

shiv wrote:I just heard from a young friend of mine. No he's no longer all that young. He has finally got a job in a major aero engine company in the US - which is what he always wanted to do. 17 years ago, in Bangalore, he was in GTRE working on the Kaveri. He used to say that the whole thing was a sham then as a young engineer. He must be 45 or 47 now. We must listen to young critics. If we allow them to grow old they become Prodyut Das types. But we don't. The criticisms of the young in India are shut out by the bureaucracy headed by Dr Pompous Trumpetwala, Padma Bhushan, Chief designer, Laser weapons dept, DRDO


It is a fact. I have many friends who are material researchers who worked as interns in one of these aero space PSUs while they were in IITs/RECs. Now they are doing their PhDs or working in big aero companies. They really look down up those projects. I often end up in verbal duels with them with me defending the projects and they dishing the attitude.

Also, I remember, when I was in Bangalore. The guy working next to me was the son of somebody placed quite high up in some lab of DRDO. I dont remember the exact time in 2008, but DRDO had a sling of achievements. I had asked him to convey my best wishes to his father. He had said his father feels that this place was utterly under-performing.

All them seem to have a problem with the attitude in those organizations. It seems creativity is curbed and one is brought down to just listen, nod, and act accordingly. Questioning something is a strict no-no.

Anyways don't start thrashing me for this post ... I am just echoing what I have heard so far from people who have some experience working in those organizations.

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Re: LCA News and Discussions

Postby Karan M » 23 Oct 2010 23:02

If you were actually working in one of those organizations, then you would have accurate information. Otherwise, you are one of the many who has heard from somebody who knows somebody who knew somebody whose father was. It is much better to actually talk to people who are there. The problem with talking to people who leave is usually their perception of the place changes as to when they are there. Few maintain objectivity. Human nature is as it is

For instance, that internship thing, is a big joke, frankly speaking, and the usual case in all companies. Many interns walk into an organization and feel they are owed the best projects, the fanciest work, the most interesting stuff. Reality is otherwise. It takes years to build up credibility, it takes years before others trust you and can treat you as dependable, and no, just because one is from IIT, II*, the world is not different.

I do run into people from across different Indian private companies to the PSUs' and of the Govt ones, so far, only a handful have had serious issues with their management or organizations and how they are run. The proportion as a percentage to the total is remarkably same.

BTW, your statement about "It seems creativity is curbed and one seems to be just listen, nod, and act accordingly." could not be more wrong especially where many of the defense labs are concerned. They are probably the handful of places in today's India where creativity still exists and is allowed to flourish thanks to the 9-5, process, process, process, culture not being used to hammer people nonstop.

In another thread, there is some report about some gizmo mentioned. The people in that team are all in their late 30s but are still in Govt employ because they are the only places where they can be respected as individual contributors and have absolute freedom to do what they want and define entire products and actually develop them. Their counterparts who went "private" have no longer got access to anywhere near that big picture. They are either managers in the private sector in engineering services leading teams of younger people (but getting paid heavily) or working on some code for a MNC which has offshored work to India. In short, you want to make something end to end, be in charge, the Govt labs are where you need to be. Very few Indian companies are even willing to invest in their people beyond the bare minimum.

This is not to say all places are the same. Some have flawed individuals in charge, others are lackluster and others have no work. In sum, the rough thumbrule I can find is this - the more work an organization has, the less time it has to while away, and people are usually occupied and productive. Over time, the flashy non performers also either leave or are left behind. But if theres little work, or the hiring policy is all wrong or limited by funding (making an engine, can only hire fresh from school engineers) then you have trouble. There will be little for them to do, and they will leave, and be very dissatisfied.

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Re: LCA News and Discussions

Postby Indranil » 23 Oct 2010 23:30

^^^ Glad to know that the perception portrayed to me is not correct.

P.S. I did not imply to say that IITians belong to a different world. :)

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Re: LCA News and Discussions

Postby Karan M » 23 Oct 2010 23:42

indranilroy wrote:Well Neela, "if it is not a looker, it will probably not be a performer" is a very valid statement for fighter jet design. By looker people mean a less draggy and clean airframe. He actually explains what he means by a looker if you read his article properly.


Sorry, but that is again, just a myth foisted onto people by slick marketing talk and the "Top Gun" stuff about uber cool super fighters. The Hawk (yes, the same plane we bought as an AJT) is considered to have "fatiguing maneuverability" when flown within its envelope. The US used Skyhawk aircraft as aggressors. What a looker..
http://www.warbirdalley.com/images/a4-02.jpg

Both could dogfight and defeat far superior "lookers".

In 1971, India's Su-7's flew through heavy ground fire and delivered substantial results, were they lookers? This is another bit of absolute rubbish in Das's articles, from his disparaging comments about intakes, where I doubt he has the foggiest idea of the intricacies of the LCA intake geometry and the trouble the designers went to, to shield the ducts, while he rah rahs the Gripen. To his great remark about APU inlet.

I think you didn't understand what he was speaking of. He speaks of a Kfir like intake to be aesthetically more beautiful (and hence the comment "lack of interest"). If you were to be building your own plane. Would you now be very interested to make it look good in all aspects. He has no qualms about performance there.


Who cares about aesthetic performance over functional utility? The Kfir, one crashed in South America recently and the Israelis have been waiting for a while to have somebody purchase them, apart from the Sri Lankans who picked up a few. A remade derivative of the Mirage, its thoroughly obsolete and what will happen when this "beautiful" Kfir goes up against one of those MiG-21 Upgrades with BVR missiles..

Meet the workhorse of the Vietnam war and the backbone of the USN fleet for a long time. Very pretty?
http://eatmypotato.com/wp-content/uploa ... hantom.jpg

What about this "aesthetically beautiful" aircraft?
http://www.smh.com.au/ffximage/2006/07/ ... x314,0.jpg

These guys clearly forgot about " make it look good in all aspects."

Das has written a lot of rubbish and tried to disguise it by covering it up with mumbo jumbo
Last edited by Karan M on 23 Oct 2010 23:48, edited 2 times in total.

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Re: LCA News and Discussions

Postby Karan M » 23 Oct 2010 23:47

indranilroy wrote:P.S. I did not imply to say that IITians belong to a different world. :)


Fair enough, but the II* institutes by virtue of peer pressure and what not, are only going to have a limited few stick around for the kind of low-medium, jobs the Govt provides. Hence, as far as I can state, for any organization or even for India to succeed, the challenge is to make the average guy/girl who graduates from any half decent college to be a productive contributor. Which is actually happening, but the more the better.

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Re: LCA News and Discussions

Postby Kartik » 24 Oct 2010 00:18

shiv wrote:Actually Prof Das argues that delta wings have inherent weaknesses that can only be addressed by FBW. Of course he has to "rub it in" by saying that even FBW only partially addresses the particular weakensses of the delta wing. Also he makes no mention of the advantages of the delta wing which can be Googled by anyone interested.

But the point Das seems to be making is that the choice of pure delta+ FBW ties the Indian designers down because they cannot do hack jobs that the Americans did by increasing the tail surface area of the F-16 (which I know nothing about) - simply because there is no space to ad a tail. According to Das, this disadvantage will manifest itself at a later stage when, for example more more pylons may have to be added - perhaps on a bigger wing which will mean rewriting of the entire code. The particular criticism he tags on to this is that the "advisers" that India has were changed from the French (who are the most experienced in pure deltas) to the Americans.

For example Das says "Oh pure delta is bad because it ties you down to FBW". Even if he is 100% correct in saying that delta may tie you down to FBW the original thought process may have been the other way around - i.e "We need a light FBW aircraft"

Having decided that the choices could have been various configurations including pure delta/double delta. If Das now asks "Why did they not anticipate all the things that I know now like the way the Americans hacked the F-16 because they wanted more pylons" I am sure the answer would be more kind to the LCA design team than Das is. But who is trying to answer it that way - i.e the way it actually panned out - with the choices they had back then. Who is defending the choice of delta wing which has its own inherent advantages? Nobody is doing that. Nobody is saying - even as a mere documentation of the history of Indian aviation design , why this choice was seen as appropriate. And after so many decades the "distinguished scientists" (Whom Das reserves special ire for) are all retired with their Padma Bhushans or whatever leaving the current LCA team to answer questions about decisions they made 2 decades ago.


Shiv, isn't the Gripen also a delta ? Did its wing size increase for its payload to go up from 4000 kgs to 5300 kgs to around 6000 kgs now ? see this pic. The Mirage-2000 had 6 hardpoints on its wings and the fuselage (2 under wings each, 1 centerline) and the Mirage-2000-5 bumped it up to 9 hardpoints. I've never read that it led to extensive re-doing of the FBW and delays as a result. Point being that it has been done in the past by other delta wing fighters and if the criticism is applied to the Tejas because it is a delta wing design, then it should be applicable to other delta wing fighters too. Maybe they were short sighted too and hence fools in the eyes of Mr Das ?

As always victory has a thousand fathers and defeat is an orphan. When the LCA is the most "Liberally Criticized Aircraft" in the world it hurts to hear a "Prof" throwing more stones. But what is required is not a dissing of the man himself but airing of alternative views.


Then I can ask- why does the Chinese FC-1 weigh 6500 kgs empty? Why does the Lockheed Martin -KAI T-50 Golden Eagle weigh 6680 kgs empty ?

Is it just the Tejas design that is overweight or does a nominal look around tell you that a design that carries 4000 kgs of external load and 2400 kgs of internal fuel and is designed to 8.5G/9G/-3G and to the much higher descent rates of military fighters, generally does weigh that much ? Even the Gripen A/B are 6800 kgs/7100 kgs as per a Flight test by Chris Yeo, who reviewed it for Flight Global.

I even searched on Flightglobal's archives and found old articles that were mentioning how the initial weight estimates for the Gripen were for 8000 kgs empty weight ! They had BAe designing the wing box and some other structures which obviously is a huge benefit since the biggest source of weight is the torsion box, ribs, spars and stringers. Who will challenge BAe's expertise in aircraft designing? They may have done a terrific job and saved a bunch of weight. Maybe we should have asked Dassault to design the aircraft for us as well in the name of time saving and that would've saved us a lot of this grief now..

are they all "F" grade designs ? Or has the man simply based his article on wikipedia figures (where they wrongly claim that the Gripen empty weight is 5500 kgs) and without adequate research blasted the Tejas ?

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Re: LCA News and Discussions

Postby Surya » 24 Oct 2010 00:48

Never be it said that a jingo cannot rebut the dodgy professor :)

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Re: LCA News and Discussions

Postby AJames » 24 Oct 2010 03:26

shiv wrote:Actually Prof Das argues that delta wings have inherent weaknesses that can only be addressed by FBW. Of course he has to "rub it in" by saying that even FBW only partially addresses the particular weakensses of the delta wing. Also he makes no mention of the advantages of the delta wing which can be Googled by anyone interested.


The prof is wrong. Relaxed stability (which requires FBW) improves performance of all aircraft, delta, canard, and aft tail configurations. With relaxed stability, drag is reduced, fuel efficiency improved, and maneuverability is improved. The very simple and obvious reason for this is that for aerodynamic stability, the wing and control surfaces have to be arranged in a way that requires permanent trim forces, and temporary turning forces during maneuvering that oppose the lift the wing is generating. This is worst on a delta, better on a canard and best on a aft tail configuration. This is the reason why all commercial civil airliners built currently use relaxed stability and FBW - it reduces fuel consumption and allows greater variance in center of gravity. Relaxed stability gives the best improvement in the case of a delta wing, which is not very maneuverable and sheds speed on turning more than the others without FBW, but a delta with relaxed stability can be as good as an aft tail with relaxed stability. The low aspect ratio of the delta will of course create more drag than a high aspect wing especially during turning, but the Mig 21, F15, and PAKFA are all aft tail aircraft with similar low aspect ratio wings.

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Re: LCA News and Discussions

Postby AJames » 24 Oct 2010 03:51

It is remarkable how close the wing plan of the LCA is to the PAK-FA (if you draw a straight line from the vortex flaps to the front wing tip). Stick a tail on it in the same proportions as the PAK-FA and you have a PAK-FLCA.

Image Image

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Re: LCA News and Discussions

Postby shiv » 24 Oct 2010 05:39

Kartik wrote:Then I can ask- why does the Chinese FC-1 weigh 6500 kgs empty? Why does the Lockheed Martin -KAI T-50 Golden Eagle weigh 6680 kgs empty ?


http://en.wikipedia.org/wiki/HAL_Tejas
The successes of the LCA IMO get covered up by falling for Prof Das's argument and looking at what the Chinese are doing. Wiki in fact has some things that should be thrown around as information liberally



The LCA is constructed of aluminium-lithium alloys, carbon-fibre composites (C-FC), and titanium-alloy steels. The Tejas employs C-FC materials for up to 45% of its airframe by weight, including in the fuselage (doors and skins), wings (skin, spars and ribs), elevons, tailfin, rudder, air brakes and landing gear doors. Composites are used to make an aircraft both lighter and stronger at the same time compared to an all-metal design, and the LCA's percentage employment of C-FCs is one of the highest among contemporary aircraft of its class.[52] Apart from making the plane much lighter, there are also fewer joints or rivets, which increases the aircraft's reliability and lowers its susceptibility to structural fatigue cracks.

The tailfin for the LCA is a monolithic honeycomb piece, an approach which reduced its manufacturing cost by 80% compared to the customary "subtractive" or "deductive" method, whereby the shaft is carved out of a block of titanium alloy by a computerized numerically controlled machine. No other manufacturer is known to have made fins out of a single piece.[53] A 'nose' for the rudder is added by 'squeeze' riveting.

The use of composites in the LCA resulted in a 40% reduction in the total number of parts compared to using a metallic frame. Furthermore, the number of fasteners has been reduced by half in the composite structure from the 10,000 that would have been required in a metallic frame design. The composite design also helped to avoid about 2,000 holes being drilled into the airframe. Overall, the aircraft's weight is lowered by 21%. While each of these factors can reduce production costs, an additional benefit — and significant cost savings — is realised in the shorter time required to assemble the aircraft — seven months for the LCA as opposed to 11 months using an all-metal airframe.[54]


The Indian government's "self-reliance" goals for the LCA include indigenous development of the three most sophisticated — and hence most challenging — systems: the fly-by-wire (FBW) flight control system (FCS), multi-mode pulse-doppler radar, and afterburning turbofan engine.[16] Although India has had a policy of strictly limiting foreign participation in the LCA programme, these are the only major LCA systems on which the ADA has had to invite significant foreign technological assistance and consultancy. Moreover, the engine and radar are also the only major systems for which the ADA has seriously considered substituting foreign equipment.

The ambitiousness of the LCA programme in terms of pursuing self-reliance in aviation technologies is illustrated by the fact that out of a total of 35 major avionics components and line-replaceable units (LRUs), only three involve foreign systems. These are the multi-function displays (MFDs) by Sextant (France) and Elbit (Israel), the helmet-mounted display and sight (HMDS) cueing system by Elbit, and the laser pod supplied by Rafael (Israel). However, even among these three, when the LCA reaches the production stage, the MFDs are expected to be supplied by Indian companies. A few other important items of equipment (such as the Martin-Baker ejection seat) have been imported. As a consequence of the embargo imposed on India after its nuclear weapons tests in May 1998, many items originally planned to be imported were instead developed indigenously .

Of the five critical technologies the ADA identified at the beginning of the LCA programme as needing to be mastered for India to be able to design and build a "completely indigenous" fighter, two have been entirely successful: the development and manufacture of advanced carbon-fibre composite (CFC) structures and skins and a modern "glass cockpit." In fact, ADA has had a profitable commercial spin-off in its Autolay integrated automated software system for the design and development of 3-D laminated composite elements (which has been licensed to both Airbus and Infosys).[16] These successes have gone mostly unnoticed in the shadow of the problems encountered with the other three key technology initiatives. Nonetheless, as a result of the accomplishments of India's domestic industries, presently about 70% of the components in LCA are manufactured in India and the dependence on imported components used would be progressively reduced in the coming years.[17]

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Re: LCA News and Discussions

Postby Indranil » 24 Oct 2010 06:49

AJames wrote:
shiv wrote:Actually Prof Das argues that delta wings have inherent weaknesses that can only be addressed by FBW. Of course he has to "rub it in" by saying that even FBW only partially addresses the particular weakensses of the delta wing. Also he makes no mention of the advantages of the delta wing which can be Googled by anyone interested.


The prof is wrong. Relaxed stability (which requires FBW) improves performance of all aircraft, delta, canard, and aft tail configurations. With relaxed stability, drag is reduced, fuel efficiency improved, and maneuverability is improved. The very simple and obvious reason for this is that for aerodynamic stability, the wing and control surfaces have to be arranged in a way that requires permanent trim forces, and temporary turning forces during maneuvering that oppose the lift the wing is generating. This is worst on a delta, better on a canard and best on a aft tail configuration. This is the reason why all commercial civil airliners built currently use relaxed stability and FBW - it reduces fuel consumption and allows greater variance in center of gravity. Relaxed stability gives the best improvement in the case of a delta wing, which is not very maneuverable and sheds speed on turning more than the others without FBW, but a delta with relaxed stability can be as good as an aft tail with relaxed stability. The low aspect ratio of the delta will of course create more drag than a high aspect wing especially during turning, but the Mig 21, F15, and PAKFA are all aft tail aircraft with similar low aspect ratio wings.


AJames. keep them coming. I find the Tejas compound delta difficult to understand. I can easily understand the cranked arrow formation, ogee delta. The canards are similar in functionality like the leading edge extensions of the cranked arrow design.

However, the Tejas wing is just opposite to all this. Please let me know (anybody for that matter) if my understanding is flawed at any point. But does the join between the two deltas actually become the point where the vortex is created. I can see that the Tejas does have vortex generators near the join in the form of the red strip (it was flagged here before by some posters as cracks). In between the bleed channel creates vortexes over the "inside" part of the wing. This is definitely a desirable characteristic which will considerably push up stall angles. Besides the stall will start at the wing root which is also desirable.

However, having the inside delta having a lower sweep angle, increases the AR which is not ideal for the manoeuvrability. Is this a tradeoff?

Also it doesn't work out well for the area ruling, right?

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Re: LCA News and Discussions

Postby Indranil » 24 Oct 2010 08:09

Also, I don't quite understand the correlation between the PakFA wing and the LCA wing.

In the Pakfa, the engines are housed more "inside the fuselage itself. So if you see if you extend the leading edge of the "primary" wing, it shall not cover the entire intake. They blended the trailing edge of the Lerx, to the root of the primary wing. Now the Lerx's leading edges had to be in the same sweep angle as the primary wing leading edge. THis is a stealth requirement. The join between the LERX tip and the inside of the "primary" wing is at the same sweep angle as the inside of the horizontal stabilator near the engine.

In this configuration the vortex generation would be at the join at the tip of the LERX. In that respect it is again same as the cranked arrow, rather than the LCA wing! Joining a line between the LERX tip and the "primary" wing tip makes a completely different wing design! It changes stall characteristics and the AR altogether.

Please fill in on what I am missing.

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Re: LCA News and Discussions

Postby vic » 24 Oct 2010 09:01

Prof something Failed to mention that FBW makes it easier to carry multiple weapon types in dissimilar arrangement.

Gripen Empty weight is more like 6800-7100kg and not 5500kg. The wing area is around 25-28 sq m + 5 sq m vs LCA 38sq m. Delta wing also allowed capacity to store more fuel while keeping the wing span short for Naval requirements

Also this lay jingo thought that slim tapered fuselage was for pushing aircraft to high Mach. When it was realized that High Mach is never reached in practical situation, it was given up (??)

Chinese Mig-21 clones had availability of only 25% and required major maintenance after 30 hours of flying. No wonder they went for Russian Engines in JF-17s. Why does Prof does not talk about the practical ssues like availibility and maintenance issues gen 2 aircraft and even early Mig-29s. Why did US give up F-14 which is loved by fanboys/critcs alike and keep ordering massive numbers of F-18s???
Last edited by vic on 24 Oct 2010 09:30, edited 2 times in total.

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Re: LCA News and Discussions

Postby shiv » 24 Oct 2010 09:16

I present to you an article full of aeronautical gobbledygook that makes no sense to me whatsoever but it sounds like it may refer to LCA also onlee.

http://pdf.aiaa.org/preview/1986/PV1986_1838.pdf

Comments?

Can anyone explain to me why the forward and inner part of the LCA's cranked double delta does not act like a canard?

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Re: LCA News and Discussions

Postby dinesha » 24 Oct 2010 09:24

DRDO to roll out own fifth-generation fighter
http://www.tribuneindia.com/2010/20101024/main4.htm
Chandigarh, October 23
While the indigenously developed Light Combat Aircraft, Tejas, is expected to receive operational clearance in the next two months and its induction into the IAF is scheduled for next year, the Defence Research and Development Organisation (DRDO) has embarked upon a project to develop its own fifth-generation fighter aircraft.

The proposed DRDO aircraft would be in the medium-weight (20-tonne) category and different from the joint Indo-Russian fifth-generation fighter that is on the cards, which is in the heavier 30-tonne category like the Su-30.


“The seed project for the new aircraft has started and is expected to be complete in about 18 months,” P.S. Subramanyam, Director, Aeronautical Development Agency (ADA), and head of the Tejas project, told The Tribune here today. The seed project would define the technical and operational requirements and lay out the broad concepts for developing the aircraft.

“Our proposed fighter would be a twin-engined aircraft in the category of the MiG-29,” Subramanyam said.

On the status of the Tejas project, Subramanyam said the aircraft trials for launching R-73 short-range anti-aircraft missiles and 1000 lbs bombs have been successful. “The 10 prototypes and pre-production variants have undertaken 1,450 sorties, which include about 200 with weapons,” he said.

The IAF has projected a total requirement for about 120 Tejas and 16 two-seater trainer variants for equipping seven squadrons, while the Navy wants 57 aircraft of this type.

The ADA is also looking at integrating the Israeli Python air-to-air missile with the Tejas to meet the IAF requirements, while the Navy wants it to examine the possibility of the Israeli Derby missiles that it already uses on the Sea Harrier. The Tejas’ avionics system, Subramanyam said, was open-ended so that weapon systems could be changed over seamlessly.

Of the 200-odd Tejas to be produced, each of which would cost Rs 200 crore, about 100 would be powered by the American General Electric 414 engine. Subramanyam said that a new project had been taken up for the development of the Kaveri engine in collaboration with French firm SNECMA that would meet the revised weight and flight parameters of the Tejas.

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Re: LCA News and Discussions

Postby vic » 24 Oct 2010 09:29

LSP-5 seems to be running pretty late, was it supposed to go up in June 2010?

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Re: LCA News and Discussions

Postby Vikram W » 24 Oct 2010 12:35

yep, it was supposed to be out in around July and was to be followed up "within a week" by LSP 6

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Re: LCA News and Discussions

Postby vina » 24 Oct 2010 12:39

And his point about Mig-29A having static stability and excellent maneuverability without FBW is pretty good


Hmm. I know I said I wont post very often. However, I spent the past few days on the 11th floor of Manipal Hospital changing diapers of a new born in a room directly overlooking Shivji's KGA Golf Course and bang at take off point of the HAL runway.. And anyway after cooing in the baby's ears and soothing him to the roar of LCAs take off , maybe it does behoove to post on this thread.

Haa. What the good prof doesn't say is HOW the Mig 29A and the SU-27s achieved their maneuver performance. There is no secret Russian Aerodynamic sauce there, but rather , it is achieved by massive excess installed thrust and huge sacrifices in payload and fuel fraction.

Now consider a similar plane with FBW and the closest analog, the F-16 A/B vs the Mig29 A/B . The F-16 because of its emphasis on FBW placed a massive premium on efficiency! Net result with the PW-100 engine @ 110 KN , you had a 600 mile radius fighter , much larger payload (approx 6T?) , more pylons (I think 2 more than the Mig 29A) and arguably better aerodynamic performance in certain parameters like roll and pitch rates and equal in stuff like sustained turn rate. The F-16 with it's small stubby wings, the elevators that didn't fight the wings with negative lift and the high bypass engines was ultra efficient. A small, efficient and brilliant package. To develop a full multi role version the F-16 C/D and later ones was from the F16A was a piece of cake . Yes, it needed a larger tailplane and a higher wing loading and stiffening of the skins of the F16, the last because it was a full monocoque design.

So chew on that you non FBW "old school" Mig 29A wallahs!. So what you basically had was point defense fighter with good A2A performance, ZERO A2G capability and persistence and range of the sort which wh*res would love from their Johns in terms of turning the most number of tricks where Wham! Bham! Thank you maam, would be most preferred. Despite such trade offs and a pure A2A optimization , the multirole F16 could largely match an in some regimes outperform the Mig29 in A2A! Real food for thought that eh?

Now what exactly had to be done to get the old Mig29 to the full multirole versions , namely the Mig29K and it's derivatives that they are fielding in the MRCA contest . Well whaddya know ! They put in a 4 channel FBW and made the plane unstable by moving the wings to the front, just like the F16 and put in all the systems and stuff for A2G! Err. they basically under the mold line fundamentally redesigned the aircraft.

Same thing with the Su-27 to the SU30 (FBW, canards etc) . The SU-27 and Mig29s were of similar design philosophies as the F-15 where A2A performance was got by excess thrust installed and zero A2G capability and a large size!.

Coming to the Jehaaj-e-Kufr, with one of the lowest wing loadings among the contemporary fighters, there is more than enough wing area to cater to a weight increase of another 2 tons still have the lowest wing loading.

And yes, like the Dassault Mirage, the LCA too is a semi moncoque design with the space frame taking most of the stress and skins very little , so a future payload increase will not result in increased skin thickness like in the F-16 result in huge weight bloat (compare Blk 52/60 with the early Blk10/15 to see the difference and the difference in weight bloat between the M2K-9 and the first M2Ks) .

So folks, dont worry, have curry. All is well (like in the 3 idiots movie) and things will be fine. Keep in perspective that the LCA is entering into the service as a full multirole version with LGB capabality and that even the BVR A2A will come later in FOC (dunno why, maybe the IAF wanted more A2G capability as a priority and feel that they have more than enough A2A capability extant maybe?) and then all the whines and pet peeves vanish away :lol: :lol: .

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Re: LCA News and Discussions

Postby Austin » 24 Oct 2010 13:20

The Achilles Heel of the original Mig-29 fighter was the old RD-33 engine , it was a real fuel guzzler and it impacted its airborne time , which made the recent AFM article on Mig-29A vs F-16 (Block 30 ) BFM which AndyB has posted some time back that the best way to defeat the Mig-29 was to avoid an engagement and keeping it airborne for longer time because it would quickly empty its fuel and will have to run home while F-16 could comfortably still stay airborne.

Beyond that Mig-29 was a great PD Air Superiority Fighter which was any thing but good in its job than what NATO and US could throw at in mid 80's , and its Sheml shot with maneuverability advantage over F-16 was a killer as later proved in many DACT conducted with the old Mig-29 in german air force.

The Su-27 has no such problem and the AL-31F was fuel efficient and gave it long leg and made a mince meat of F-15 when they visited US in early 90's , the MKI still proves that in many exercise , it shows that TSAGI knew what they knew

Both did not have A2G capability initially beyond the rudimentary ability to drop dumb bomb because the Soviets had Su-24 and Mig-27 to do that job , during those era much of the fighter in Soviet inventory were specialised for its role and were good in what they did against its potential cold war enemy.
Last edited by Austin on 24 Oct 2010 13:53, edited 1 time in total.

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Re: LCA News and Discussions

Postby negi » 24 Oct 2010 13:36

vina wrote:Haa. What the good prof doesn't say is HOW the Mig 29A and the SU-27s achieved their maneuver performance. There is no secret Russian Aerodynamic sauce there, but rather , it is achieved by massive excess installed thrust and huge sacrifices in payload and fuel fraction.

It is not correct , does all that huge T/W ratio make the Mig-25/31 maneuverable ?

The fulcrum and the flanker designs today are pretty much the benchmarks for maneuverability what were termed as fancy airshow maneuvers by the west and Unkil are now being aped by the Raptor and the SH.

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Re: LCA News and Discussions

Postby saps » 24 Oct 2010 13:53

[quote]does all that huge T/W ratio make the Mig-25/31 maneuverable ?[/quote]

Well how come no one is talking about the lifting fuselage design which ruskies and then yankies have moved onto....Gyani' ppl please elaborate.

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Re: LCA News and Discussions

Postby vina » 24 Oct 2010 13:54

negi wrote:It is not correct , does all that huge T/W ratio make the Mig-25/31 maneuverable ?

Lets get some facts here. Google Chaccha can be of help. Why dont you find the T:W ratio of the Mig25/31 vs the Mig 29 and Su-30 and also the T:W ratio of the F16 and F15 ?

The fulcrum and the flanker designs today are pretty much the benchmarks for maneuverability what were termed as fancy airshow maneuvers by the west


Yawn.. The "fancy airshow maneuvers" are just that. If you want the fanciest airshow plane, that will not be the SU-30 , but rather the SU-31 :rotfl: :rotfl: . BTW, just look for the pics of the SU-31 and see what a super dooper plane that is!

The question is really not about the maneuverability, but HOW that is achieved and WHAT they had to give up on the other side to get that performance level on one side.

Sorry folks. Facts are facts. Prof Pradyut da etc are fine. But the pre FBW age is gone the way of the dodo. Even the Rodina has given up on it. It would have been an incredible and terribly stupid mistake to get a non FBW plane into service for a plane designed in the 80s and 90s.

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Re: LCA News and Discussions

Postby negi » 24 Oct 2010 14:12

^ Yeah the foxbat has in fact a lower T/W ratio but omission on my part notwithstanding the T/W is not the only factor which contributes to maneuverability which is what I was trying to convey. Fancy airshow maneuvers might not be of any relevance in an actual air duel but what they do definitely show is the overall handling and maneuverability of the AC itself there are definitely no two ways about it; in fact that is why those Raptors in flying demos these days do those cobras or backflips all the time for that is the only amriki AC capable of doing it (may be SH too).

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Re: LCA News and Discussions

Postby Gaur » 24 Oct 2010 14:46

Have to agree with Negi here. Although the need of FBW cannot be stressed enough, there cannot be any doubt that Su-27's agility was unmatched at that time. Even with all the ridiculing of the Su-27 as an airshow plane by western analysts, their super duper F-22 seems to be doing exactly at airshows what Su-27 did decades before. Su-27's nearly limitless AOA can surely not be termed as airshow gimmick. Su-27 was originally designed to be an air superiority fighter and it excelled in that. It was arguably the most maneuverable aircraft of its time and its range was good for its role.

Though, of course, without fbw Su-27 could never have been transformed into Su-30MKI and Su-35s.

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Re: LCA News and Discussions

Postby shiv » 24 Oct 2010 17:06

Gaur wrote:Have to agree with Negi here. Although the need of FBW cannot be stressed enough, there cannot be any doubt that Su-27's agility was unmatched at that time. Even with all the ridiculing of the Su-27 as an airshow plane by western analysts, their super duper F-22 seems to be doing exactly at airshows what Su-27 did decades before. Su-27's nearly limitless AOA can surely not be termed as airshow gimmick. Su-27 was originally designed to be an air superiority fighter and it excelled in that. It was arguably the most maneuverable aircraft of its time and its range was good for its role.



Going back to the Prodyut Das article one finds that he is an equal opportunity critic.

His irritation with FBW shows in his article - but it is not criticism of the LCA. he says that FBW was touted as being needed for maneuverability (F-16) until the MiG 29 arrived, after which the FBW people started saying that FBW was needed for the exact opposite purpose - i.e to prevent over stressing the airframe.

The other very interesting criticism made regarding the single engine of the LCA hits out at the snake oil salesmen of the west who (like Indians) did not know how dusty and hazy Indian skies are with smog and how engines in Indian skies get battered by dust particles unlike the clear air of the temperate regions. There is a 24x7 cloud of volcanic dust over the matrubhoomi. Twin engines are just that much more reliable under these conditions. Note how the MiG 29 and the MKI are the only twin engined combat a/c of the IAF after the Canberra and the HF 24. Having said that I bet Das himself did not realise this when he was young. This information (smog over India doing things to engines) was something I heard in the 80s and 90s timeline and later from sources like my late cousin Suresh and Baldev Singh.I do not recall reading about it earlier. But kudos to Das for putting it in print so people outside the business also learn.

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Re: LCA News and Discussions

Postby NRao » 24 Oct 2010 18:12

His irritation with FBW shows in his article - but it is not criticism of the LCA. he says that FBW was touted as being needed for maneuverability (F-16) until the MiG 29 arrived, after which the FBW people started saying that FBW was needed for the exact opposite purpose - i.e to prevent over stressing the airframe.


(I have not been able to download that article, so have not read the entire thing.)

Having said that, a few general observations:
* software being touted first for maneuverability then to restrict it, is natural progression in software utilization. Happens all the time - even today.
* My recollection is that FBW/software was used to set the limits on the F-16. It did both, make it "maneuverable" (we called it make-a-brick-fly) and set the other extreme, where the pilot could not do anything he pleased now that he KNEW he had a brick that did plenty of tricks (which was over stressing the airframe)

Perhaps I have to read that article before I make more specific comments, but based on the above, I am not sure what his grip is.

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Re: LCA News and Discussions

Postby shiv » 24 Oct 2010 19:27

NRao wrote:
(I have not been able to download that article, so have not read the entire thing.)

Having said that, a few general observations:
* software being touted first for maneuverability then to restrict it, is natural progression in software utilization. Happens all the time - even today.
* My recollection is that FBW/software was used to set the limits on the F-16. It did both, make it "maneuverable" (we called it make-a-brick-fly) and set the other extreme, where the pilot could not do anything he pleased now that he KNEW he had a brick that did plenty of tricks (which was over stressing the airframe)

Perhaps I have to read that article before I make more specific comments, but based on the above, I am not sure what his grip is.


NRaogaru - what you say is right - but the tone I get from Das's words is one of criticism of design bureaus who sold "latest and greatest" to the world to make their packet and that was bought hook line and sinker by early LCA designers.

A lot of what Das writes is basically "If my aunt had a di*k she would have been my uncle" - but his description of that aunt is interesting.

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Re: LCA News and Discussions

Postby Gaur » 24 Oct 2010 20:20

shiv wrote:.......the tone I get from Das's words is one of criticism of design bureaus who sold "latest and greatest" to the world to make their packet and that was bought hook line and sinker by early LCA designers.

A lot of what Das writes is basically "If my aunt had a di*k she would have been my uncle" - but his description of that aunt is interesting.

Sir,
I seriously cannot understand how ADA could have "bought hook line and sinker" the argument made in favour of FBW. To be very basic, what was FBW originally touted for? To allow an aircraft with static instability to fly. So, do you think that the ADA aero engineers did not even know if a statically unstable aircraft would prove to be of worthwhile advantage? FBW would only come if you first design an unstable airframe. So, in its core, it was more of a matter of a physics and I think it very unlikely that ADA would have taken the trouble to design an unstable design (and ultimately freeze it) if they did not think it would not be worthwhile. It only makes sense. Why would ADA embark upon a much more difficult task if it believed that similar results can be obtained with much less effort.

All right, India had no experience with FBW but it did have some experience with aerodynamics through HF-24, Ajeet and various other wind models of proposals. It was not as if ADA just made a pretty looking drawing on paper and tried to make it fly. They would had obviously tried various designs (which by all accounts they did) and studied the pros and cons of all of them. One can very well say that HF-24 was designed by Kurt Tank, HAL's only aerodynamic change to Ajeet was adding a small control surface and all the rest of the proposes were paperwork (which would all "arguably" be true). So, perhaps one would question the LCA designers' ability to understand the aerodynamic effects of static instability. But if the designers could not figure that out, they had no business of creating even a wind tunnel model (no exaggerations here). And from the safety record of LCA, we can safely assume that the LCA designers were no twits. So, hopefully they could understand effects of static instability too.

Of course, aircraft design is a very difficult business where the results can be very surprising (eg: Su-27) but you cannot start a project if you do not have some level of confidence on your paperwork and simulations.

So, will the LCA benefit from FBW? May be, May be not.
But did ADA design a FBW aircraft just because the rest of the world touted it as the next best thing? Does not seem possible to me.

ADDED LATER: My layman understanding on FBW is this. Static instability (and in extension FBW) does not guarantee greater maneuverability. It simply gives a designer more freedom to design an aircraft. How the designers makes use of that is upto his skill. It may be totally possible that another set of designers may design under full constraints static stability and still produce a superior aerodynamic platform. So, FBW is an added option and it is up to the designers to decide whether they have the skill to utilize it or not.
Of course, for totally radical designs like the flying wing (which seems to be the new fashion at present), FBW becomes a necessity.
Last edited by Gaur on 24 Oct 2010 20:45, edited 1 time in total.

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Re: LCA News and Discussions

Postby shiv » 24 Oct 2010 20:39

Gaur wrote:
So, will the LCA benefit from FBW? May be, May be not.
But did ADA design a FBW aircraft just because the rest of the world touted it as the next best thing? Does not seem possible to me.



Going by Das, the LCA would not fly without FBW. I am sure it benefits a great deal. That is Das's biggest complaint. Das believes that the LCA would have been useless without FBW and developing that is what tied India down.

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Re: LCA News and Discussions

Postby Gaur » 24 Oct 2010 20:58

^^
Sir,
I think you misunderstood me. Of course LCA cannot fly without FBW as it is a statically unstable aircraft (how did that come into question?). So, in that sense it would certainly benefit from FBW. My argument was different.
Let me put it this way. Will LCA be able to fully utilize the potential of Static instability and perform as the designers hoped when they froze an unstable design? That is an answer only the people actively involved in the project can give.

However, you seem to have deviated from the point. Your said understanding of the author's belief was that the LCA designers just gulped the lie of the world regarding FBW. My post was regarding why I think that is highly unlikely.

So, whether " whether LCA would be useless without FBW" or "whether developing FBW tied india down or not" was not a topic at which my reply was directed at.

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Re: LCA News and Discussions

Postby shiv » 24 Oct 2010 21:14

Gaur wrote:
However, you seem to have deviated from the point. Your said understanding of the author's belief was that the LCA designers just gulped the lie of the world regarding FBW. My post was regarding why I think that is highly unlikely.


So you are telling me that you disagree with my understanding of what Das writes? I am fine with that. But what do you think Das means? What I think is irrelevant and what you think of what I think is even less relevant.

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Re: LCA News and Discussions

Postby Indranil » 24 Oct 2010 21:46

You guys are confusing what Prof Das said. He didn't speak out against FBW as a technology. He says that the weight of the equipments for FBW stays the same immaterial of the plane size. So a light plane takes a relatively higher penalty (weight gain percentage wise). However there are ample examples of planes designed in the past without FBW which were sufficiently maneuverable. Also given a light plane one enjoys a higher TWR (typically) and hence can overcome some limitations by not having the FBW.

As far as my understanding of his article goes, he wanted India to field a good and light fighter within 4-5 years since the inception of the plan, build up numbers and have the data to optimize/refine the airframe or a new airframe. Now we have a plane which is still not optimized and has not still been fielded. Also we are lacking numbers.

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Re: LCA News and Discussions

Postby shiv » 24 Oct 2010 21:53

Das is critical of the choice of a Delta wing because that made the use of FBW inevitable. Das implies that if the design had been a tailed delta or an aircraft with a tail it would have been more in keeping with the route that most aircraft designers of the world took, bar the French. And even the French stepped out of deltas after the Mirage 2000. Apparently deltas are good for high speed high altitude flight and are worse for slow and low altitude flight (and, although Das does not say this also demand high landing speeds if they are without FBW).

Das is also critical of pure deltas because he says they slow down in turns with the huge wing acting like an sail.

But what Das does not do is speak of the cranked double delta design which I thought makes a great deal of a difference. I don't know - but nobody is saying much about that.

Clearly there must have been some valid reasons why this design was chosen over others. There must have been some thoughts, choices and deliberation. Absolutely no information exists about that. Who conceived of the cranked double delta design? All this has taken place in the 1980s and is history. That history remains a mystery.

What is well known (from Wiki) is that India wanted to develop a "Light Combat Aircraft" while developing 5 critical technologies.
    FBW
    Composites
    Engine
    Glass cockpit
    Radar

The LCA was held hostage by FBW and engine. Das seems to claim that the FBW part need not have been as critically paralysing as it was had the original design for a "Light Combat Aircaft" not been a delta.

I have no way of knowing how right or wrong he is. But who knows? And who will tell?

Given that the design was frozen as a tailless cranked double delta the designers and developers have done well and their experience should be carried forward. But if mistakes were made in the 1980s that led to delays - let us know how those mistakes were made. Or let is know that no mistakes were made. Let us know if the ASR demanded specs that inevitably pointed to a delta design. It is a typically Indian phenomenon to not rake up old issues because some respected elder may be shamed. Is that what is happening here? We need not shame or curse anyone but I would like to know how and why why a "cranked double delta design was conceived?

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Re: LCA News and Discussions

Postby Rahul M » 24 Oct 2010 22:09

>> And even the French stepped out of deltas after the Mirage 2000.

not so. rafale. in fact worldwide there is a clear move towards deltas, EF, rafale, gripen, J-10.

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Re: LCA News and Discussions

Postby shiv » 24 Oct 2010 22:12

One of the bitter arguments that we had during the nuke yield discussions was the idea that nuclear bomb designs should have been peer reviewed as suggested by one of the critics. In fact this led to the question "Exactly how many nuke bomb designers does India have?"

The same question can be put about aircraft designers. Just how many successful, well known, experienced aircraft designers did India have in the 1980s? Of course, when India wanted a "Light Combat Aircraft" I can say with 20/20 hindsight that it would have been nuice if 2 or 3 teams with 2 or 3 different designs concepts for a Light Combat Aircraft were asked to build concept models and do feasibility studies to be studied by a peer group for selection.

But I suspect that just like nuclear bomb designers, combat aircraft designers in India were so few as to be counted n the fingers of one hand. And perhaps only one of them was heading the lab in charge - suppressing everyone else because his date of birth and his joining government service was earlier than others.

So one guy and his team probably thought of the tailless cranked delta. If there was opposition or if there were other designs we don't know. These questions are important for the future of aviation in india and must not be brushed under the carpet.

Ten years ago there was a concept picture for the MCA which was a flying wing IIRC. Now its shape has changed.

This was India's MCA back then:
Image

What is it now?

Does India have only one concept for each of these advanced designs. Is it not possible to think of 2-3 competing designs? Or do we just not have enough people? The latter may be the problem.
Last edited by shiv on 24 Oct 2010 22:19, edited 1 time in total.


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