Nick_76Nick how is the composite going into the LCA ?? Is it the honeycomb type setup which we see or is it a monolithic type setup ?? for the fuesalage that is!!
If I remember correctly, its a combination of both…this is a pretty old article from 5 years back..
Dreams lighten in LCA
Sqn. Ldr. B.G. PrakashAdvanced composite units at NAL and HAL were established. Both have been instrumental in supporting HANSA, SARAS and the LCA. Prahlad says that bridging a technological gap – as in handling the composites – is more important than satisfying the design aspects. Assemblies with fasteners, bolts, rivets get replaced by monolithic composite components. The spin off is easily absorbable in space launch vehicles and guided missiles, where reusability and pilot’s lives are not issues.
Significant Achievement
The use of composites results in a 40 per cent reduction in the total number of parts: For instance, 3,000 parts in a metallic design would come down to 1,800 parts in a composite design. The number of fasteners has been reduced to half in the composite structure from 10,000 in the metallic frame. The composite design helped to avoid about 2,000 holes being drilled into the airframe. Though the weight comes down by 21 per cent, the most interesting prediction is the time it will take to assemble the LCA — the airframe that takes 11 months to build can be done in seven months using composites.
Involvement of British Aerospace
A component that has curvature, bend and sharp edges may look easy to be formed with composites. But its strength and stress-bearing capacity at certain points is difficult to measure and to improve upon. Tooling design is the most critical requirement in composite technology. The skin of the LCA measures 3 mm at its thickest with the average thickness varying between 2.4 to 2.7 mm. The skin needs to bear a force of 100 Newton per mm. What the designers initially achieved was just 40 N/mm. With some improvements it reached 60 N/mm. Interaction with BAe offered some solutions. BAe is reported to have achieved 160 to 180 N/mm which was a challenge. It came to light only later that they were working with skin thickness of 6 mm. This was a lesson well learnt when composites were used in the bulkhead and stiffener underneath the skin.
T – Pull
The T-Pull problem was another headache for the designers. T-pull occurs at skin and stiffener edge. It includes two forces: One force which acts perpendicular to a surface is referred to as ‘sigma z’. The inter-lamination shear stress the trme to assemble the LCA – the airframe that takes along the surface is the other. The flat top of a T-joint meshes with the surface of a composite panel. Adhesives hold them together. The ‘leg’ of the T joins the flat top not in a perfect mesh – but creates a triangular void at the junction. This is termed as the Bermuda Triangle. Forces tend to pull the leg away from the top; the initial design could withstand only 40 N/mm. An innovative introduction of a thin composite interface strip between the flat top of T and the surface improved the strength dramatically to 60 N/mm. From a basic design scheme it graduated into padded configuration and overlay configuration. Failure was expected at the joints – which did not happen.
On the fuel tank floor, horizontal and longitudinal stiffeners cross each other. At the point of crossing, the longitudinal members are cut out to allow the breadth-wise members to pass through. This process is intricate and special tooling was necessary. Stiffeners join the surface in T-joint and need to be perpendicular to the surface – at exactly 90 degrees!
Research and analysis are continuing to make the T-joint stronger. Adhesives and reinforcement are used to fill the void. Flex cores are used which not only look simple but also elegant. Stitches to bind the flat top of the T to the surface is another method. The recommendations of BAe helped and further progress is foreseen. A ‘duct dividing wall’ made of composites, which reduces the number of parts and fasteners, is another indigenous effort. It was conceived against existing norms. Complex tool is developed to work on an area measuring 3 m by 1 5 m made of composite. Baffle frame stiffener in fuel tank needs precision engineering.
Air Duct
The Air Duct is a monolithic piece that needs stiffeners. Generally stiffeners protrude outward or inward depending on the component. But the surface of air duct is to be smooth and protrusion of stiffeners cannot be outward lest it obstruct free airflow. So stiffeners are embedded and internal. According to Simha the consultant, one of the ‘two best parts’ designed is used where the air duct enters the fuselage, with four external and two internal stiffeners, which replaces nearly 30 metallic components. A conventional design could have been used. In the conventional sandwich design, two thin skins called face sheets of 0.3 mm to 1.5 mm thickness are separated by honeycomb struts made of aramid based nomex. The separated space of 10 mm to 20 mm is mostly hollow. Sandwich panels are used in under carriage door, hatches or panel covering the armament bay. Repeated failure was encountered at the inner skin of the air intake with the sandwich design, using metal or composite adopted until then. The other best part is the Y-joint in the floor of the fuel tank with longitudinal stiffeners along the body.
Y – Joint
The Y-Joint is an innovation in the airframe of the LCA where the air duct joins the floor of the fuel tank. Centre fuselage holds the fuel tank which is 2.5 m long. This part needs to handle hook stress and bending stress with the skin being 2.4 mm thick. A monolithic composite part that replaces several metallic pieces was developed. It merges with a counterpart at the bottom, which contains the fuel tank floor. Prevention of fuel leakage is of prime importance. Simha conceived of a small extension at the edge of the top piece, in a new design, which had to mesh with a similar receptacle in the bottom part in a Y-shaped joint. One arm of the Y runs to a length of 1.75 m along the fuel tank floor. No one was sure that it could be manufactured to required specifications. NAL helped. With stiffeners both inside and on the external surface, the secondary bonding technique was successfully used to a length of 1.75 m. The scientist who made this says: “One learns from nature. Branches of trees join the trunk usually in a Y-joint. It must be naturally strong.”
Fin and Torque Shaft
The fin for the LCA is a monolithic honeycomb piece. No other manufacturer is known to have made fins out of a single piece. The torque shaft for actuating the rudder is a challenge. It is built on additive process. The cost of manufacture reduces by 80 per cent from Rs 2.5 million in this process. This is contrary to a subtractive or deductive method normally adopted in advanced countries, when the shaft is carved out of a block of titanium alloy by a computerized numerically controlled machine. A ‘nose’ for the rudder is added by ‘squeeze’ riveting.
LCA has hats
Yet another innovative design is stiffener of hat section. It has a cross-section that resembles a hat in sequences, it endured the tests and worked well. A honeycomb sandwich piece measuring 400 mm in breadth was not reflecting the required strength to withstand shear forces. Other manufacturers have used similar designs. Within the breadth of 400 mm a hat like cross-section, six or seven in number, successively linked in sequence in the stiffener, is tried in the design. In fact about 30 per cent of the composite material is carved out from the original strip. Hollow portions are created. Yet the design proved capable of withstanding larger shearing forces. It is an optimisation of shape. Engineers use Finite Element Analysis in optimising. FEA computer software are available. Now, an engineer can develop new software based on this design. Autolay — the software used by designers in the project — is fondly mentioned.
Section 5435 and 8385
Composites are used in the inner skin at air intake on section 5435 of the front fuselage, at section 8385 of the rear fuselage and at the external skin of rear fuselage. The policy statement stipulates that small cutouts in the airframe are to be minimised; only large cut outs for access are acceptable. Where the straight stiffeners did not provide the required strength, flanged reinforcements were successfully tried. Benefits accrued in achieving improved buckling factor and consequently effected manageable stress concentration.
Lightning Strikes
When lightning strikes the LCA, four metal longerons stretching from end to end, afford protection. In addition, all the panels are provided with copper mesh. One out of five is ‘bonding’ bolt with gaskets to handle Electr-Magnetic Interference. Aluminum foils cover bolt heads while the fuel tank is taken care of with isolation and grounding.
Corrugated Composite and Test
Some components are of sheets that taper down from a thickness of 9 mm to 3 mm. Obviously, the lamination should dwindle without losing strength. A corrugated finish, which is meticulously achieved, is used. NAL has the only Non-Destructive Test facility in India using ultrasonic tests with frequency varying from 1 to 10 megahertz to test composites. It is needed at many stages in development. Result is in the form of colour images and is analyzed.
Indian Institute of Technology, Powai is involved in providing test boxes, which replace a few test panels. Ultrasonic based testing is necessary on composite surface, which does not show cracks but can have de-laminated layers. Dent shows up on composites though the design allows for barely visible damage to the skin, which may not grow. Moisture is absorbed by composite but the design takes this into consideration. A portable ultrasonic test gear is under development, which can be used in field formations.
SARAS is Thinner
The passenger aircraft under development, SARAS, has control surface that uses composite sheet of 0.6 mm thickness. Squeeze riveting used here is more sophisticated. Technology usable on a sheet with 3 mm thickness cannot be directly adopted.
Appropriate Technology
Plaster of paris is used to make moulds on which composite sheets of the required thickness including the taper are shaped. Surface of the mould needs to be absolutely plane, which is provided by smoothly machined granite tabletops on the workbench. Templates support the plaster block on both sides. The compound solidifies by normal sunlight. To prevent shrinking, solidifying compound from losing its surface grip on the template, screw and nut are inserted on the template. The nut acts as locking nut. Depending on the complexity, the number of screw holes increase. Appropriate technology is in use in the most sophisticated aircraft that this country has seen.
From a level of non-use, composites now form nearly half of the airframe, which carries 30 per cent of the total weight of the aircraft. At times, wealth of information gets poverty of attention – more so with the LCA. May the will of each Indian fly with it!
Nick_76My reply was to Victor’s: he said news about LCA is genuine …. But my view is no matter where the news comes from, internet, newspaper or horse mouth, you got to use your brain, otherwise, just take a look at all the LCA news for all these years.
I dont see where anyone here said dont use a brain. The need for a brain is obvious- whether Asian or Indian or Chinese or Thai. 🙂 But the issue is that information available for the LCA is in spades, and every little issue is catalogued, so going by that & saying rumours is uncharitable. If one was to be fair- the same could be said of programs everywhere which suffer from the same issue.
Now, you are talking about another point: program transparency. I absolutely agree LCA, India enjoys much better transparency compared to J10, China.
But, Let’s have a closer look at transparenc issue. First it’s for the general public. I do believe no matter in which country, military projects transparency is very limited in this regard. Compared to the whole project criteria, no matter it’s LCA or F22, the amount of information available for public consumption is only enough for propaganda purpose. It’s not enough for any external org. or person to do a serious technical assessment. In other words, you are only fed with what they want you to believe. And that’s why general public are always getting surprise after surprise and has to agree with budget rise again and again. Face it, ordinary Joe on the street is not capable to monitor any military project.
I would disagree here to some extent. The fact is that if you are in anyway associated with a respectable organization (& not from Pak / China – ie rivals), obtaining information on the LCA project in particular is far more easy vs most other projects.
Was the detailed information on the LCA’s flutter testing for propoganda? Is the detailed information available on some of the LCAs avionics available- including the architecture & actual details of the operational software, merely PR? I disagree- because I know of people who were actually concerned about the information being released & debating whether it needs to be curtailed, but its available anyways.
The issue of transparency is not meant for PR anyways beyond a point- its to allow the taxpayers to understand whats going on with public funds, and corrective decision making when mistakes are obvious. For instance, the recent Indo-US nuclear deal is a case in point. The GOI cannot state its position openly and is actually being deluged by attacks, information from many sources and criticism. But this is for the public good. They had to meet & agree about all the critique from the Indian scientific community & assure them of a fair say. Now if the entire process was opaque, the decision makers would be cut off from the public and do whatever they wished.
The situation is not perfect, a lot can be done to improve it- but overall, open information allows for better corrective measures.
And this leads to the second layer of transparency: Auditing. Believe me, China has General Auditing Committee as well. And couple of years ago, there’s a news report picture showing the director of the General Auditing Committee visiting China’s No1 Aviation Corp, (which is the holding company of most chinese fighter manufacturers), what the director was looking at was a board showing the major projects: J10, J11A, J11B and KJ2000.
See this is what you are not getting. Perhaps we didnt say it clearly or confused our message. Are those audit reports available to you? If they were- then I assure you, you would see all those delays, all those cost overruns and stuff based on the same in the media- which would of course be rumours etc. The point is India releases all this information.
Its very rare that anything is redacted. For instance tell me this:
How many radars of any particular type is the PRC going to procure? But from the Indian audit trail I can tell you the type and number and the competitors.
This has pros and cons – from the security perspective, but that is why you see so much doom and gloom about the Indian defence procurement as well, as compared to volume of information.
But, would you then give china credits on J10 because they do have internal audits? No chinese forumers gave a damn about it. Audit is only to make sure the whole project is not falling out of control dramatically, especially in financial terms, it’s not to gurantee J10 is able to handle a particular rival. If you take your LCA as an example you should see your CAG did not help much either.
Your chinese forumers dont give a damn about it, because it is not open to them. If it were, they would peruse it for details. Also the media would be eager to scoop it up & use it for a) sensationalism b) political purposes c) plain old reportage. By closing the audit process to publicity, the audit itself becomes reduced in terms of impact.
But thats the PRCs choice.
This topic reminded me a real joke happened in HongKong. After 1997 when the new airport was in use, once the new computer system for lugage management was down for a day or something, and the democratic party immediately requests the HK government to allow the elected legislative members (although only few, because others were all appointed by China) to form an investigation committee so that the “real” peopleo of HK could monitor and know what happened, but after several hours of initial meeting, they had to delegate the investigation to a professional committee because none of those elected politicians knew computer softwares. And the funny thing is, before 1997, the Queen appointed HK governor would ask the same professional guys to do the investigation, directly.
The Indian audits are by a) Beancounters b) Elected parliamentarians who call technical personnel to depose before them c) Company audits
So its a multistep process. For publically listed defence firms, they have to release yearly details of financial performance to product information. I prefer the open market approach myself, and thats what the Indian defence industry is moving towards.
So, my point is, all these transparency, democrocy, auditing are good to have. I am not against them. But, you have to remember, building a fighter jet is building a fighter jet, essentially it’s a science activity, all those good things are not the critical parts of a fighter project, especially the technical area. Those are political good things and they are meant to handle political issues. Don’t expect those good things to magically increase or decrease some technical capability.
Sure – i dont disagree. I am just pointing out that looking at media sensationalism of reportage or delays in the program and using those as examples of rumours is not accurate.
Nick_76J-10 is possibly still under initial operational testing, but no matter what it’s hard to argue J-10’s testing in much larger number is the same progress as a few LCA prototypes. Unfortunately Indian government usually likes to take her time to do everything in defense, like it or not. Sometime for valid reasons, other time not, but it’s slow nevertheless.
However comparing the technical performance or stating which one is better is purely speculation right now. It’s not “easy” to tell without more numbers (official or not). Eyeballing the airframe size doesn’t give enough precision to judge T/W ratio, not to mention the unknown drag and lift. Without these two fundamental figures, no one would have even the roughest parameters of flight envelope to any degree of certainty, much less the AoA / pointing ability, subsonic/supersonic performance, or energy-maneuverability. The radar, datalink, and weapons performance details are also unknown so what you get is unknown overall vs. unknown overall in air combat. Range cannot be guessed by external looks alone, the fuel consumption rate and fuel capacity are both needed. The large Su-27 has longer range than MiG-29, but there was the example of Boyd intentionally designed smaller F-16 to have longer range than F-15 at beginning.
The only thing that could be said with relative accuracy is the combat load comparison because that has high degree of direct correlation with physical size.
Oh, and anymore of the “this is obvious”, “details aren’t important”, or “I say it’s likely” stuff, I think we know what to ignore.
Excellent posts.
Nick_76It might serve you well in future to read and understand what is being said before making a reply.
That applies to you as well. So stop the faux outrage and speak politely. :rolleyes:
Harry seems unable or unwilling to determine which is the more capable aircraft between the J10 and FC1. I was merely pointing out how obviously easy it is to tell which of the two is superior even without this pointless obsession about ‘exact stats’.
If its that easy, put your money where your mouth is and come up with the exact stats to prove that its performance is indeed superior. But you dont have that do you? Quoting meaningless generics about how “obvious” it all is, doesnt count for nuts.
Most of us are willing to rise above this juvenile mine is bigger than yours obsession & live & let live. If you cant, then mores the pity.
Nick_76The Su-30MKI features composite materials as well AFAIK and is not a complete “metal monster”. The Su-37 was a single piece a modified Su-35, but it does not only included the AL-31FU TVC engines but also a non moveable throttle, side stick an seat inclined by 30° and french LCDs and HuD, as well as the N-011M PESA instead of the N-011 MSA used by the Su-35 and LINS+GPS. Some sources report about ELINT/SIGINT equipement for the Su-37 demonstrator. In fact the aircraft was reengined with conventionel AL-31F in 2000 and all non russian systems were removed and replaced by russian ones. Additionally the aircraft received an improved FBW system which increased the aircrafts agility without TVC.
The Su-37 contributed technologies for the Su-30MKI like the N-011M and the AL-31FP are finally a further developement of the AL-31FU.
BTW the Su-35 was as multirole capable as the Su-30MKI and also featured an rearward looking radar. If the Su-35 would enter production a lot of newer technologies would be integrated. The Su-30MKI however is a customized version including a lot of non russian avionics.
Sukhoi is now concentrating on the Su-27M2 aka Su-35(BM).
With 90% of the LCA composite, the MKI may also receive some more significant amounts of composite material for weight/ RCS reduction etc..
http://www.bharat-rakshak.com/IAF/Info/11BRD.html
Typos corrected:
Concealed in a discreet corner is a specialist section working on composite materials for the MiG aircraft. With carbon glass as the ingredients, the BRD team has developed composite exteriors for the wings and fins of the aircraft to replace heavier alloys and metals, thereby reducing in considers (considerable) amount weight of the aircraft and in the process, add(ing) tremendously to its speed and manoeuvrability.
Nick_76There’s one difference you’ve not mentioned: the USA is giving Pakistan weapons, while France & Sweden are selling weapons. And you propose sanctions against France & Sweden, but not the USA? Tell me, why do you treat them so differently?
Good point.
Nick_76Anyways, even without offically released specs, its easy to tell which of the two is superior. Engine thust, which is a give figure for both; using airframe size to judge weight (not to the exact kilo, but enough to tell which is the heavier), hence having a rough idea of range and/or payload; using images to compare the radome size etc, its all basic stuff, and why you would refuse to accept the blindingly obvious is most puzzling.
Then give the exact stats, if its so blindingly obvious. From aerostructures, components, subsystem performance, overall performance. I can similarly nitpick and point out holes in official data available.
Theres no refusal to accept anything, instead all thats being said is that there is no point in getting into a game of one upmanship. You can have the J-10, the Indians their LCA & either side can believe what they wish, but please do stay off the comparisons.
Nick_76Comparing LCA and J10 is indeed meaningless. I agree completely.
But, from an observor’s point of view, no matter who delievers the news, I always use my brain to analyse the news itself, rather than blindly believe it.
Sorry to say this, but Indian printed media’s news about LCA is not much more trust worthy than annonymous chinese internet rumors. Were those indian’s news correct, LCA should’ve been in service last decade, or atleast the LSP production should’ve started in 2004, or the order of 20 LCA should’ve been placed 2 years ago, or at the very least PV3 should’ve been flying in Feb 2006.
Just take a look at the recent LCA news as an example, “28 LCA will be inducted by 2007”, sorry, I would rather believe a rumor like “by Feb 2006 China produced 100 J10”.
The question was and is of program transparency. If someone wants to take a dig and say : ” Aha my bird is better, its got more pictures on it”, then please face the other side of the coin as well & not shift the goalposts!
Your contention would also ensure that programs like the JSF (how many times overbudget already?) or the EF (how many delays did it have?) or many others would also be classified as rumours or whatever.
The issue of open informatin has pros and cons. Every tiny defect is catalogued, mistakes are sensationalized – but it does serve as a check on the developers.
Besides the above is exactly why the oversight mechanism is necessary.
Lets take two hypothetical examples.
Paper A says that the LCA sucks, and IAF has ordered 40 Mirage 2000s instead. But the papers available at the parliamentofindia.nic.in website clearly show the opposite & then you know the report is BS.
The Sun claims that the EF is a flop because xyz weapon is not integrated. Questions in the Hansard (& the replies) rubbish that and say the opposite.
The PRC has its own way to deal with the issue & I am not mocking it, but to insist that one system is better than the other – well I disagree.
Nick_76Except that the engine orders were already delivered as per Salut. 37 orders of LCA isn’t fulfilled by far.
GDs statement was wrt the question was of program viability indicated via support. The 37 orders with 20 more options are more than the FC-1s at this point of time, and the GOI has committed itself to IOC and FOC which is sufficient to address that exact claim.
And somehow, all that still makes the LCA fly? I’m not interested with reports and bureaucracy, i’m interested on one simple thing, when LCAs are finally in IAF colors, insignia and unit numbers, in an IAF military base, and at least in enough number to make one squadron. All reports are worth their weight in paper until you can show me this happens.
Talk wrt the context please. GD made the claim that a) One is known thanks to the Pak Govt b) The other is known due to National Geographic.
Thats clearly and patently false.
You may not be interested in Indian reports and bureaucracy, but those reports and bureucracy act as oversight and ensure a proper feedback mechanism to ensure that the developers stick to their word. And contribute to overall program transparency which is more than either PRC fighter.
Nor are is the PAF in anyway, as open about its military procurement system or program critiques as India is, to tom tom them as an example as GD did. I would state that the PRC itself is more open than the Pak. side.
Nick_76If they were delivered and put into planes then it most certainly is. At the moment, we know there are only four prototypes.
Dont shift the goalposts. You said orders. In that vein 37 have been ordered, pure and simple.
There is far more world press coverage of the FC-1 than the LCA. We know exactly how many prototypes, the days of initial flights, etc. We even got taxing tests and assembly pictures.
The FC-1’s engine, radar (or lack thereof initially) and number of aircraft for its main customers were all public from the very beginning.
We even saw design changes like the DSI andd enlarged LERX in models months before we saw it on the live aircraft prototype 04.All this was chronicled in some of the largest and longest running threads on AFM. There were simply massive amounts of material on it.
Dont mistake PR for program transparency. For the LCA there are details ranging from its test pilots report on flutter tests, to Harrys detailed report one every aspect with info from HAL and ADA as well as audit and oversight reports to know whats what. In contrast, all you have are mostly photographs and press releases. Theres a world of difference between both programs in terms of program transparency.
Nick_76The J-10 is a viable aircraft since we KNOW that there are over 100 AL31FN engines delivered for it, we have no idea if the LCA is.
By the same standards, with 37 orders already, its clear that the LCA is a viable aircraft.
It is in prototype stage but is “rapidly nearing service.” Whereas Indians can quote National Geographic, FC-1 followers can quote the Pakistani government.
ROTFLMAO @ the spin. Indians can quote their own Govt, audit reports, test pilots reports and more besides on every detail of the project including access to the developers and meeting them in person. Please do inform us when you can do the same.
Nick_76Its not a question of merely IOC, but overall program transparency. If folks want to beat around the rhetorical bush about mine is bigger than yours comparisons, then they better be upfront & admit that they are limited in terms of information as well. If one makes categorical comments about technologies & performance & how one is better than the other, than pony up the exact evidence as well.
The problem is that the moment someone even raises these kind of topics, it becomes a shouting match. BTW, this kind of unseemly stuff is exactly what I had anticipated & asked for the mods to avoid by giving this silly thread a long deserved burial.
The Chinese can have their J-10 and the Indians their LCA. No point in dragging other through the muck saying which is better.
Nick_76A few days before the war, I would use AESA/MESA radar tech to send high bandwidth streaming video into the S-400 command van displays saying there are 200 free 10 day flight/hotel tour packages to Vegas. First come first serve for all S-400 operator techs. Just show up with a page from the S-400 operators manual as proof of I.D. Thats how you de-fang a stiff integrated air defense. :p
:rolleyes: 😀 😀
Nick_76Awesome info BIO!!
Nick_76The Phalcon is L Band. I’ll check up on band vs AESA modules and get back..:)
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