LCA Tejas: News and Discussions

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Karan M
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Re: LCA Tejas: News and Discussions

Postby Karan M » 14 Feb 2015 20:17

Wow, Navy has managed to get themselves a significant design change!

Image

Image

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Re: LCA Tejas: News and Discussions

Postby Karan M » 14 Feb 2015 20:21


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Re: LCA Tejas: News and Discussions

Postby Karan M » 14 Feb 2015 20:28


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Re: LCA Tejas: News and Discussions

Postby Cosmo_R » 14 Feb 2015 20:54

The F-35 is supposed to let the pilot see 'through the floor' using exterior cameras. Wondering then why droop noses are needed if you can use cameras to see the carrier deck while landing. The A380 has nose wheel mounted cameras.

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Re: LCA Tejas: News and Discussions

Postby Karan M » 14 Feb 2015 21:13

Cameras can malfunction & std ones dont provide depth perception.

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Re: LCA Tejas: News and Discussions

Postby sankum » 14 Feb 2015 21:32

My maximum estimate for NLCA mk2 is MTOW of 16T from ski jump of a aircraft carrier if emergency rating thrust of 12T can be provided by giving ede enhancement to GE414 engine.

Empty weight 7T+ internal fuel 3.5T+ pilot/cannon ammo/chaff/flare/weapon pylon 0.5T+5t payload=16T MTOW.

Can anyone get exact figures from Aero India 2015.

Anyway the brochures are a pleasant surprise.

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Re: LCA Tejas: News and Discussions

Postby putnanja » 14 Feb 2015 21:32

Why did the IAF Mk-II version stuck at 13.7m while that of IN is 14.56? How the L/D ratio and aerodynamics affect the lengths of IAF & IN versions? The wingspan is bigger too for IN version. Is that due to levicons? The IN version is almost 1.36m more compared to mk-I while IAF version is 0.5 m more.

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Re: LCA Tejas: News and Discussions

Postby Karan M » 14 Feb 2015 22:20

Looks like for all the commentary/requirements mentioned, IAF didn't really work with ADA on significantly modifying the LCA. To be fair, that could be because they want a Mk2 fast.
Navy seems to be willing to take higher risks and commit to a product customized to their specific needs. That flight article also indicates the same.

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Re: LCA Tejas: News and Discussions

Postby Karan M » 14 Feb 2015 22:26

Clearly, Navy has said to heck with the MiG-21 sized dimensions constraints and asked ADA to meet expanded range, payload configurations. This is brilliant, though I (subjectively) dont like the raised cockpit of the N-Mk2.

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Re: LCA Tejas: News and Discussions

Postby Karan M » 14 Feb 2015 22:54

Better that way. JSF is perfect example of trying to force a common design on everyone and running into issues.

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Re: LCA Tejas: News and Discussions

Postby Karan M » 14 Feb 2015 22:59

In an ideal world, we should have taken the NLCA-Mk2 and AF'ized it. It will clearly be more capable than the AF version in several respects. Lower drag and more fuel. But I guess the IAF wants the plane fast.

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Re: LCA Tejas: News and Discussions

Postby brar_w » 14 Feb 2015 23:33

Karan M wrote:Better that way. JSF is perfect example of trying to force a common design on everyone and running into issues.


The largest issues with the JSF that have led to the most cost or time delays have been computing, sensor integration and software build/volume related. The weight saving measures were directed at the Beach version and therefore the efficiencies gained have positively affected all variants of the jet. The only slip up in terms of common design that stands out was the decision that was taken to accommodate the USN's demand for a larger bomb bay capable of carrying larger bombs (2000 lb bomb instead of 1000 lb bomb). The modeling done at that end was not thorough and no one thought to de-risk the fact whether a STOVL version could meet its critical weight targets while accommodating the larger payload needs. As it turned out the skunks designed a very good STOVL aircraft for a 1000 lb bomb bay capacity (1000 x 2, which had been the demand of the USMC and USAF since the JAST program started), something that the folks at Fort Worth had to fall back on post the re-design.

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Re: LCA Tejas: News and Discussions

Postby Karan M » 15 Feb 2015 00:13

Look brar_w, I don't want to waste your time and mine, with a slanging match. Its not merely time delays but the platform design itself which has come under severe criticism. What you are talking about is what those in the industry refer to as the execution part. That's a different issue when the requirements laid down in the beginning are messed up to begin with.

Its pretty well known by now what a boondoggle it was to combine three differing mission/user service requirements into a single platform which has all sorts of service imposed constraints including the Naval, Marine & AF ones and hence imposes baseline performance costs on the airframe across the board. A mini-F22 for the AF, some different fighter for the Navy & a third for the Marines may have been more expensive but may have ended up with better performance for each of the respective services. If you argue against this, then you are pretty much on the wrong side of every objective eval of the program. The outer mould line of the JSF-CTOL has been affected by the other two services putting constraints on size & other aspects.

Same applies here. Flawed requirements will lead to flawed decisions. Converting the LCA AF to LCA Navy had similar issues. And apart from taking something AF and making it naval, the AF's specs for the LCA were flawed in one critical aspect. LCA AF being constrained by MiG-21 form factor. This forced the designers to try and make a pocket fighter only to run up against physical constraints & now in Mk2, a 0.5m plug is being added. But even this is not sufficient for the Navy.

Navy is not seeking to go with these limited steps but has asked exactly for what it wants. AF is again going for something more conservative. Worst would be to take the LCA AF and try to convert it again into a LCA Navy Mk2. That's the point I am making. Make a conservative, one size fits all fighter and everyone will crib. Best to give the AF what they want & Navy what they want. I daresay, one day the AF may well adopt the LCA Navy Mk2 as an AF Mk3. That would be true irony!

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Re: LCA Tejas: News and Discussions

Postby srai » 15 Feb 2015 00:24

Karan M wrote:In an ideal world, we should have taken the NLCA-Mk2 and AF'ized it. It will clearly be more capable than the AF version in several respects. Lower drag and more fuel. But I guess the IAF wants the plane fast.


That would make it "MMRCA" category ... the IAF wouldn't want that now ;)

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Re: LCA Tejas: News and Discussions

Postby brar_w » 15 Feb 2015 00:39


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Re: LCA Tejas: News and Discussions

Postby Karan M » 15 Feb 2015 00:51

srai wrote:
Karan M wrote:In an ideal world, we should have taken the NLCA-Mk2 and AF'ized it. It will clearly be more capable than the AF version in several respects. Lower drag and more fuel. But I guess the IAF wants the plane fast.


That would make it "MMRCA" category ... the IAF wouldn't want that now ;)


srai, wicked, wicked. I think you might have laid your finger on a key point why some folks may not have wanted an upscaled LCA...but hey who knows, let the Navy do what it is doing and the IAF might get a chance to ask for a bit more. :)

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Re: LCA Tejas: News and Discussions

Postby Indranil » 15 Feb 2015 05:33

Woah! That LCA Navy Mk2 is a big surprise for me! But they have removed the compromises of converting an AF fighter to a naval fighter. They modified the internal structures so that the MLG is attached the way it should be not like the body builders arms like in Mk1. They have also made it retract straight up into a new fairing on the sides. This will free up internal space for more fuel. But this will also increase the wave drag. Therefore they lengthened the aircraft to overcome that. The increase in length meant the fin had to be made taller. The wing are had to be increased as the weight of the plane went up. Notice that the AF version does not need the extra fairing for the MLG, and no subsequent increase in length etc.

The interesting part is the extended trailing edge wing-body fairing. Are they going for F-16 styled airbrakes? This would also make sense. The current airbrakes create an uncommanded pitch up moment which is handled using the FBW. In the LCA Navy Mk2 this moment will increase as the airbrakes will be further away from the CG with the increase in the length of the plane.

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Re: LCA Tejas: News and Discussions

Postby Shreeman » 15 Feb 2015 05:56

Call it a different name and model. Separate the goals from Mk1. Like J11/J15? etc. Its a reasonable design.

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Re: LCA Tejas: News and Discussions

Postby shiv » 15 Feb 2015 06:31

Cosmo_R wrote:The F-35 is supposed to let the pilot see 'through the floor' using exterior cameras. Wondering then why droop noses are needed if you can use cameras to see the carrier deck while landing. The A380 has nose wheel mounted cameras.

Saar F 35 is vertical landing. Deck below needs to be seen. Yelseeyaay needs vision forward and sides and down for landing. F 35 not only has camera - but huge hole a large pankha blowing air down through a second hole in fuselage aft of murga-khadda

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Re: LCA Tejas: News and Discussions

Postby Indranil » 15 Feb 2015 12:25

I have just one complaint with that LCA Navy Mk2 design.

I feel there is some empty space just behind the cockpit. Probably, more fuel could have been packed in.

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Re: LCA Tejas: News and Discussions

Postby member_28108 » 15 Feb 2015 13:21

Probably some avionics modules will be crammed there

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Re: LCA Tejas: News and Discussions

Postby NRao » 15 Feb 2015 13:27

Trends are towards miniaturizing. Cramming would be a tmp solution. Few years down they should have more space in the LCA.

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Re: LCA Tejas: News and Discussions

Postby srin » 15 Feb 2015 15:52

indranilroy wrote:I have just one complaint with that LCA Navy Mk2 design.

I feel there is some empty space just behind the cockpit. Probably, more fuel could have been packed in.


Can they move the pilot seat a bit behind and above for better rear visibility and free up additional space in the nose for IRST ?

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Re: LCA Tejas: News and Discussions

Postby Karan M » 15 Feb 2015 19:52

that raised hump of a cockpit is an eyesore to be sure.
reminds me of an extreme version of this
http://upload.wikimedia.org/wikipedia/c ... _1967.JPEG

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Re: LCA Tejas: News and Discussions

Postby Karan M » 15 Feb 2015 19:55

srin wrote:
indranilroy wrote:I have just one complaint with that LCA Navy Mk2 design.

I feel there is some empty space just behind the cockpit. Probably, more fuel could have been packed in.


Can they move the pilot seat a bit behind and above for better rear visibility and free up additional space in the nose for IRST ?


looks like they want the pilot view to be as close as possible to the nose for better fwd visibility.

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Re: LCA Tejas: News and Discussions

Postby neerajb » 15 Feb 2015 22:43

I didn't get why they partially covered the canopy? They could have done something similar to Mig-29K/KUB i.e. just put a fuel tank/equipment in place of rear seat under the existing canopy. Are there any benefits of this approach?
Last edited by neerajb on 15 Feb 2015 22:44, edited 2 times in total.

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Re: LCA Tejas: News and Discussions

Postby Karan M » 15 Feb 2015 23:02

i think they are designing the trainer first & the single seater is a modified trainer. that back of the canopy (covered) is basically the second seat.

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Re: LCA Tejas: News and Discussions

Postby Viv S » 15 Feb 2015 23:58

Cosmo_R wrote:The F-35 is supposed to let the pilot see 'through the floor' using exterior cameras. Wondering then why droop noses are needed if you can use cameras to see the carrier deck while landing. The A380 has nose wheel mounted cameras.


That'll unfortunately be a 'head down' system. The image will be viewed on a 5" x 5" MFD; lower visual acuity coupled with loss of peripheral awareness is acceptable for carrier operations. They could develop something like the EODAS for the Tejas but it'll be a very long, very expensive process even if they tied up with an experienced contractor like Elbit. Would be more feasible for the AMCA.

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Re: LCA Tejas: News and Discussions

Postby Sancho » 16 Feb 2015 06:00

indranilroy wrote:Woah! That LCA Navy Mk2 is a big surprise for me! But they have removed the compromises of converting an AF fighter to a naval fighter.


Not really, since the NLCA will remain to be based on the AF trainer and even most of the MK2 changes, that infact are mainly required by IN (navalised engine with high thrust, additional fuel tanks...), will be based on the internal changes of the AF version too.

indranilroy wrote:They modified the internal structures so that the MLG is attached the way it should be not like the body builders arms like in Mk1.


Here as well, they have modified the internal structures of the MK2 (of both versions), to implement the new engines, the additional fuel tanks, which also is the reason for the 0.5m lengthening of the AF version, compared to the MK1 AF version. A similar increase is obviously needed for the NLCA, the question here however is, what is the base length of the twin seater MK1 and how many was added to it with the MK2 changes?
Note that all the older brochures of LCA MK2 and NLCA MK2 from Aero India 2011, base their specs on single seat varients for AF and IN, while we now now that the NLCA single seater is just a modified twin seater. That might explain why the AF varient remains with a height of 4.4m, while NLCA MK2 now is given with 4.64m.

The changes to retract the gears into the fairing is the main difference, that seems to be specific for the navy and we have discussed that some time back, when I asked why ADA / DRDO didn't redesigned the gearbay similar to what Saab did at the Gripen NG, since the main internal changes to integrate the new engine and additional fuel tanks are similar + it would had opened the chance for additional weaponstations.
Now they interestingly had done it, but "only" for the naval version and "without" any advantages to carry more weapons, which hardly makes sense, since they could had designed the AF version with the same fairing, but a lighter version of the naval gear. The AF would had benefitted from more fuel too and might also be able to free wingstations from fuel tanks, by the increased internal fuel + the centerline fuel tank. That also counters the increased drag of the fairing, since they don't need large external fuel tanks anymore, but now the AF MK2 might still dependent on 1200l fuel tanks in the strike role and remains to be limited to 7 weaponstations only.

indranilroy wrote:I have just one complaint with that LCA Navy Mk2 design.

I feel there is some empty space just behind the cockpit. Probably, more fuel could have been packed in.


The space is filled with avionics and a fuel tank below it:

http://picload.org/image/cpdlcll/np2rear.png

http://picload.org/image/cpdlcli/n-lcacross2.png

The problem of rear visibility should be obvious too as a shortfall of that design, but the bigger issue however is the question how much empty weight the final NLCA MK2 will have and how much that counters the thrust as well the useful payload during carrier take offs?

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Re: LCA Tejas: News and Discussions

Postby shiv » 16 Feb 2015 06:13

Just curious. How is it that people on BRF discover "design shortfalls" by simply looking at photos which are not noticed by either the test pilots or designers, and which on previous occasions have made BRFites ask the concerned people at Aero India only to be educated that all these "design shortfalls" are not really design shortfalls for the simple reason that ignorant judging from photos is a poor way of making such judgements and that there are good reasons for features being as they are

Everyone on here is an expert but no one has even seen an LCA live from close up. Exactly what is it that is being passed off as "intelligent discussion about design faults" on here? None of you ever had to pass an exam by simply sending in your photo and having it judged by an examiner who did not know the subject he was testing. So what makes this discussion anything more than trash on here?

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Re: LCA Tejas: News and Discussions

Postby Sid » 16 Feb 2015 06:20

^^^ same logic goes for people passing judgment when they see a pic of JF 17 and J 20!!

People never seem to question analysis passed on by reputed publications like Janes as well, which most of the time makes assumptions by looking a just pictures.

But this concept is called wisdom of crowd, which kindof works on discussion forums.

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Re: LCA Tejas: News and Discussions

Postby Indranil » 16 Feb 2015 06:33

Sancho wrote:
indranilroy wrote:Woah! That LCA Navy Mk2 is a big surprise for me! But they have removed the compromises of converting an AF fighter to a naval fighter.


Not really, since the NLCA will remain to be based on the AF trainer and even most of the MK2 changes, that infact are mainly required by IN (navalised engine with high thrust, additional fuel tanks...), will be based on the internal changes of the AF version too.

May be you are right. But does not look like it. Time will certainly tell.
Sancho wrote:
indranilroy wrote:They modified the internal structures so that the MLG is attached the way it should be not like the body builders arms like in Mk1.


Here as well, they have modified the internal structures of the MK2 (of both versions), to implement the new engines, the additional fuel tanks, which also is the reason for the 0.5m lengthening of the AF version, compared to the MK1 AF version. A similar increase is obviously needed for the NLCA, the question here however is, what is the base length of the twin seater MK1 and how many was added to it with the MK2 changes?
Note that all the older brochures of LCA MK2 and NLCA MK2 from Aero India 2011, base their specs on single seat varients for AF and IN, while we now now that the NLCA single seater is just a modified twin seater. That might explain why the AF varient remains with a height of 4.4m, while NLCA MK2 now is given with 4.64m.

The changes to retract the gears into the fairing is the main difference, that seems to be specific for the navy and we have discussed that some time back, when I asked why ADA / DRDO didn't redesigned the gearbay similar to what Saab did at the Gripen NG, since the main internal changes to integrate the new engine and additional fuel tanks are similar + it would had opened the chance for additional weaponstations.
Now they interestingly had done it, but "only" for the naval version and "without" any advantages to carry more weapons, which hardly makes sense, since they could had designed the AF version with the same fairing, but a lighter version of the naval gear. The AF would had benefitted from more fuel too and might also be able to free wingstations from fuel tanks, by the increased internal fuel + the centerline fuel tank. That also counters the increased drag of the fairing, since they don't need large external fuel tanks anymore, but now the AF MK2 might still dependent on 1200l fuel tanks in the strike role and remains to be limited to 7 weaponstations only.

I don't think that you have followed the LCA that closely. The current LCAs all versions are 4.4 mtrs high and 13.2 mtrs long. The Mk2 IAF will be 4.4 mtrs long and 13.7 mtrs long. Now they are extending the plane to make it more "fine". Adding a fairing "like you suggested" would beat the entire purpose. That is why, you don't see the fairing in the IAF Mk2 version. With the IN version, they have elongated the plane more to 14.56 mtrs. The increase in height of the fin is commensurate to the increase in length to 4.64 mtr.
Sancho wrote:
indranilroy wrote:I have just one complaint with that LCA Navy Mk2 design.

I feel there is some empty space just behind the cockpit. Probably, more fuel could have been packed in.


The space is filled with avionics and a fuel tank below it:

http://picload.org/image/cpdlcll/np2rear.png

http://picload.org/image/cpdlcli/n-lcacross2.png

The problem of rear visibility should be obvious too as a shortfall of that design, but the bigger issue however is the question how much empty weight the final NLCA MK2 will have and how much that counters the thrust as well the useful payload during carrier take offs?

I know how NP2 looks behing the seat. I was speaking of mk2 (space marked in red). Also, I don't think that the rear-visibility is any better or worse thanits contemporaries. The IAF has always got very high marks on cockpit visibility.
Image

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Re: LCA Tejas: News and Discussions

Postby Sid » 16 Feb 2015 06:49

^^ back seat of NP2 looks really cramped with LRUs and equipment.

Where does all this equipment go in twin seat version? Does this make single seat varient more capable then twin seat due to extra mission critical equipment it can carry?

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Re: LCA Tejas: News and Discussions

Postby shiv » 16 Feb 2015 06:57

Sid wrote:
But this concept is called wisdom of crowd, which kindof works on discussion forums.


"kind of works" is an accurate and honest assessment but it also indicates that the aviation discussion on BRF cannot be taken seriously. Given that people on BRF often assert that BRF is ahead of the curve or that BRF is a one stop knowledge shop, this "kinda works" assessment should serve as a warning for anyone who thinks he can actually learn right from wrong on the discussions on the military forum.

Not that I am hankering for them to return but we lost too many informed people because of too many fakin experts. BRF's loss is to its own detriment - but after one fake expert passes his gasment er judgement there is no stopping an entire herd of eggspurts from passing their gas on here - and this has now been happening on the aviation threads for about 7-8 years now - completely replacing some real stalwarts with inside knowledge who have simply moved on. Not that they are unhappy - they keep off because they know that BRF is now a fake expert forum. Gone are the days when a person would state that he might be mistaken. Nowadays no one is mistaken on BRF. What this means is that a real pilot, retired or in service is less likely to come on BRF and stay on BRF because he has to answer all our resident geniuses and aviation, aerodynamics, air warfare who know everything there is to know.

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Re: LCA Tejas: News and Discussions

Postby neerajb » 16 Feb 2015 08:00

Karan M wrote:i think they are designing the trainer first & the single seater is a modified trainer. that back of the canopy (covered) is basically the second seat.


Actually I was wondering why did they faired it over and not just paint half the canopy. But this pic posted by Sancho shows that the canopy is merely painted over.

Image

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Re: LCA Tejas: News and Discussions

Postby shiv » 16 Feb 2015 08:18

On the business of paper being pasted over canopy, "painted over" etc it appears to me that people who seem to know one heck of a lot about "design" don' t seem to have a clue about design iterations in complex systems. This is the kind of in depth knowledge that drives sales of fairness creams promising to convert SDRE to TFTA in one step.

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Re: LCA Tejas: News and Discussions

Postby shiv » 16 Feb 2015 08:22

Sid wrote:Where does all this equipment go in twin seat version? Does this make single seat varient more capable then twin seat due to extra mission critical equipment it can carry?

Yes sir. You got that 100% right. More fuel, more avionics more stuff. 1 less pilot and seat.

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Re: LCA Tejas: News and Discussions

Postby Philip » 16 Feb 2015 10:02

Shiv,latest Vayu has a feature on the LCA,in the website . AM PR has much to say .Lots of info about progress,timeframes for Mk-1/2,etc. and challenges that lie ahead.2 decades to achieve planned production. We most likely won't be there when the run is complete!

Ps.Can you give me a "tinkle"-you have my no or e-mail yours to me.

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Re: LCA Tejas: News and Discussions

Postby Kartik » 16 Feb 2015 11:13

indranilroy wrote:Woah! That LCA Navy Mk2 is a big surprise for me! But they have removed the compromises of converting an AF fighter to a naval fighter. They modified the internal structures so that the MLG is attached the way it should be not like the body builders arms like in Mk1. They have also made it retract straight up into a new fairing on the sides. This will free up internal space for more fuel. But this will also increase the wave drag. Therefore they lengthened the aircraft to overcome that. The increase in length meant the fin had to be made taller. The wing are had to be increased as the weight of the plane went up. Notice that the AF version does not need the extra fairing for the MLG, and no subsequent increase in length etc.

The interesting part is the extended trailing edge wing-body fairing. Are they going for F-16 styled airbrakes? This would also make sense. The current airbrakes create an uncommanded pitch up moment which is handled using the FBW. In the LCA Navy Mk2 this moment will increase as the airbrakes will be further away from the CG with the increase in the length of the plane.


Surprise for me as well..last AI-’13, the length of the LCA Navy Mk2 was stated as being the same as that of the IAF LCA Mk2. I was aware that the new fairing would be added to accommodate the landing gear and that the wings would get pushed out for that, but this additional length is a positive surprise. The wing area increasing was also not something mentioned then, so it’s quite clear that the design has progressed much more since then.

Like KaranM, I’m not pleased with the canopy design. A smaller canopy, like that seen in brochures of the LCA Navy Mk2 from AI-’13 would be a better approach, unless it was coming in the way of area ruling concepts.

Your observation on the possible F-16 style split airbrakes is also the same as mine- will see if I can get that answered at this AI, if I do get to go.

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Re: LCA Tejas: News and Discussions

Postby Karan M » 16 Feb 2015 11:24

vikrant wrote:
Karan M wrote:i think they are designing the trainer first & the single seater is a modified trainer. that back of the canopy (covered) is basically the second seat.


Actually I was wondering why did they faired it over and not just paint half the canopy. But this pic posted by Sancho shows that the canopy is merely painted over.

Image


Painted over, or is that an insert in place of the acrylic/composite typically used for the canopy? I think its a quick way to get the NLCA Mk1 out of the door without having to a detailed redesign of the rear portion of the trainer cockpit. Perhaps same method is being applied for the NLCA Mk2. Use the trainer design as the standard and the single seater follows thereafter with the rear portion of the two seat cockpit filled up with avionics and covered up (albeit with a single piece canopy and only the front seat. But overall looks and everything else the same. No change in aerodynamics etc & approximately the same weight allocated for the second seat.


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