LCA News and Discussions

Katare · Post by **Katare** » 11 Mar 2012 21:28

me too......i still can't get to front page

pralay · Post by **pralay** » 11 Mar 2012 22:17

tejas wrote:OT but is anyone else having a problem accessing BR via http://www.bharat-rakshak.com? I have had to search for BR via google then directly go to the forum via the google provided link.

yes,
the link http://bharat-rakshak.com is down for more than past 24 hours.
The main website is down.
I check the DNS and found that this forum is however on another server so is working fine.

Cain Marko · Post by **Cain Marko** » 11 Mar 2012 23:11

it's bad news for the LCA programme all-round.

From the NLCA article above.

BS! Why is it bad news all round? Didn't the LSP 7 just fly? And these problems can be licked - making a naval fighter out of such a small frame was never going to be easy....

SaiK · Post by **SaiK** » 11 Mar 2012 23:44

I am wondering why it is not possible to have worthiness pre-certification during design phase itself. We have enough data to show it is worth or not. I understand the difficulties in building one, but I can't understand the difficulties in preventing some shape or design earlier, so that it can save millions of moolahs, and plus customer confidence and billion hearts sinking low. This is a high visibility project right?

Minds with the right questions should be allowed to build prototypes.. and do small scale worthiness tests. If it is all about weight, then one can also think about T:W aspects of certifications as well. Intelligent designs can help reduce weight, but may require advanced engineering setup.

I think, we have not really established core areas of metallurgy and combustion science and test facility good enough.

Indranil · Post by **Indranil** » 12 Mar 2012 03:04

I have had this question for a long time now and could not find an answer myself, so throwing it out there:

Why is there a gap in the upper part of the engine exhaust and the fuselage? Click the image to view it more clearly.

Gripen and F-18 using the same engine do not have this gap.

LCA TDs/PVs used to have some extra exhaust channels near the exhaust (totally 4 of them, metallic in colour) but did not have the gap between the exhaust and the fuselage.

{Quick fact: Notice the wing body blending used to continue till the end of the fuselage in the TD. It was chopped up to stop earlier in the PVs and continued in that form till LSP-5}

Does anybody know what pupose does the gap in the fuselage and the upper part of the engine exhaust serve? And specifically why is it only the upper side is uncovered?

S_Prasad · Post by **S_Prasad** » 12 Mar 2012 06:48

The "Gap" that you are talking only appears on the top side of the enine exhaust, if you magnify the picture you can see that the bottom part of the exhaust blends nicely without any "Gap" into the body. Also I suppose that the top part doesn't have the "Gap" but it is some sort of cover (like the washer we put on screws to close the gaps)

Indranil · Post by **Indranil** » 12 Mar 2012 07:09

S_Prasad wrote:The "Gap" that you are talking only appears on the top side of the enine exhaust, if you magnify the picture you can see that the bottom part of the exhaust blends nicely without any "Gap" into the body.

Isn't this what I said:

indranilroy wrote: Does anybody know what pupose does the gap in the fuselage and the upper part of the engine exhaust serve? And specifically why is it only the upper side is uncovered?

S_Prasad wrote: Also I suppose that the top part doesn't have the "Gap" but it is some sort of cover (like the washer we put on screws to close the gaps)

No sir, that is not the case ... the gap on the top vs 'no gap' at the bottom is clearly visible on any LSP. Also that this feature was not present in the TDs and the PVs is clearly visible.

shiv · Post by **shiv** » 12 Mar 2012 08:13

indranilroy wrote:I have had this question for a long time now and could not find an answer myself, so throwing it out there:

Why is there a gap in the upper part of the engine exhaust and the fuselage? Click the image to view it more clearly.

Are you referring to the gap between the afterburner nozzle and the rear part of the base of the tailfin (which ends at the orange parachute housing cap)?

That gap is to allow movement (expansion) of the afterburner nozzle when the afterburner kicks in. In the other aircraft the nozzles are well behind.

vina · Post by **vina** » 12 Mar 2012 08:33

Hmm. From the TD to the latest LSP 7, the rear seems a little different. In the LSP 7, it looks like that the rear has been extended by around 1.5 ft or so, with a tapering section from where the rear ended in the LTD and PV earlier to the start of the after burner "petals". So the talked about "plug" in the rear , with the continuation of the strake all (you can see a new metal plug) that ended rather abruptly extending all the way to the rear and ending in a fine section.

Together with the intake in the spine and the plug in the rear (and if someone can compare the nose of the TD/PV with LSP 7, the nose now is probably more 'fine' as well now, I think), it looks like some amount of aerodynamic refinement has happened been worked into the LSP 7.

With the engine being shifted rearwards, I wonder what they did with the internal space that got liberated. More fuel perhaps ?

Hallelujah! . No wonder the LSP 7 took this long (in addition to the plumbing issues). This would have required quite a bit of rework along with recalibrating the FBW software for the changed CG etc.

Sid · Post by **Sid** » 12 Mar 2012 09:26

No Shiv, he is talking about this gap. Same thing was bothering me too.

Looks like due to frequent updates to plane for testing, they do not put back everything (unless it actually required to be in there

)

Cain Marko · Post by **Cain Marko** » 12 Mar 2012 09:40

Wah Indranilji kya tez nazar hai - sharp eyes you got amigo!

A very laymanish guess (also fantasy I s'pose) based on peewer lahori laagicks, from yours truly fwiw:

The gap allows for ahem, air cooling thereby providing reduced heat signature from the engine exhaust. Also, it is on the top part of the engine because heat travels upwards (hence the top part of the engine is hotter onlee, and requires more cooling, wot?)

Btw, other LSPs too show this gap, does it have anything to do with the IN20 engines that are only on the LSPs?

Having shared my illiterate two bits about aircraft design, I now look forward to some illuminating posts from resident gurus. Kartiksaheb anpanyas amantran ahe, kuthey gelat?

CM

Cybaru · Post by **Cybaru** » 12 Mar 2012 09:52

Are you sure the engine has moved around ? The petals/fairings in one are closed while in the other pic are open. The open and closed positions may be causing the length to seem different ? Perhaps it is just an illusion ? Maybe kosher to compare early prototypes with petals closed in versus the one in flight.

Gurneesh · Post by **Gurneesh** » 12 Mar 2012 09:59

There is nothing different in LSP7 from the rest apart from those more streamlined things (dunno what to call them) at the rear.

Here is a PV2

We can see the same step on the top half of the engine plus the longer rear (as compared to TD pics shown above).

Here is side profile of LSP4 which shows the same step profile and longer rear, but lacks the extended rear things (??) that LSP7 has and of course the intake is different.

So, the only visible changes from LSP5 to LSP7 should be the APU cooling and the extended things (??).

Indranil · Post by **Indranil** » 12 Mar 2012 10:09

CM sahab, please let go of the 'ji' for me.

I am not saying that this is a new feature of LSP7 ... it has always been then on LSPs. Infact, one can see the clear transition in PV2 from the all covered to the 'topless design:
Before:

After(becoming shameless in the company of LSPs):

May be the answer to my question lies in this picture. The bottom side of GE404 definitely could not have been left open like the top.

Then the question changes to why is that gap required? Be rest assured that it is not for heat signature reduction. It could be for heat exchange and hot air rising up will play a insignificant role when air is travelling around something at near or over the speed of sound

.

Cain Marko · Post by **Cain Marko** » 12 Mar 2012 10:36

^ My guess is that the IN-20 engines, which started only with the LSPs are to be blamed for utter disregard for modesty. Although of course Tejas is a buff guy and can therefore bare a bit without as much shame (not to sound sexist or anything).

Cain Marko · Post by **Cain Marko** » 12 Mar 2012 10:39

vina wrote:Hmm. From the TD to the latest LSP 7, the rear seems a little different. In the LSP 7, it looks like that the rear has been extended by around 1.5 ft or so, with a tapering section from where the rear ended in the LTD and PV earlier to the start of the after burner "petals". So the talked about "plug" in the rear , with the continuation of the strake all (you can see a new metal plug) that ended rather abruptly extending all the way to the rear and ending in a fine section.

Together with the intake in the spine and the plug in the rear (and if someone can compare the nose of the TD/PV with LSP 7, the nose now is probably more 'fine' as well now, I think), it looks like some amount of aerodynamic refinement has happened been worked into the LSP 7.

With the engine being shifted rearwards, I wonder what they did with the internal space that got liberated. More fuel perhaps ? Hallelujah! . No wonder the LSP 7 took this long (in addition to the plumbing issues). This would have required quite a bit of rework along with recalibrating the FBW software for the changed CG etc.

Vinaji, pardon the layman eyes, but I see absolutely no difference between the rear of LSP 1, 2, 3 etc and 7. How do you figure that the engine has moved further back?

Kartik · Post by **Kartik** » 12 Mar 2012 11:51

Cain Marko wrote:Wah Indranilji kya tez nazar hai - sharp eyes you got amigo!

A very laymanish guess (also fantasy I s'pose) based on peewer lahori laagicks, from yours truly fwiw:

The gap allows for ahem, air cooling thereby providing reduced heat signature from the engine exhaust. Also, it is on the top part of the engine because heat travels upwards (hence the top part of the engine is hotter onlee, and requires more cooling, wot?) Btw, other LSPs too show this gap, does it have anything to do with the IN20 engines that are only on the LSPs?

Having shared my illiterate two bits about aircraft design, I now look forward to some illuminating posts from resident gurus. Kartiksaheb anpanyas amantran ahe, kuthey gelat?

CM

CM, mee ithe aahe..mee resident expert toh nahi, pan mee pan stumped aahe regarding why there is a gap. I don't see any particular reason for that..I initially thought that perhaps it has something to do with the F-404IN20 engine as opposed to the F2J3 but I did start comparing LSP-2 onwards to see if this gap existed back then or not and this gap has existed on LCA variants, even going back to PV-3 (KH2005). Perhaps and I may be totally wrong here, the reason is that the first few LCAs were designed keeping the Kaveri in mind and the F-404 was meant to be an interim fit, but as the Kaveri was delinked from the LCA program, the fuselage diameter near the nozzle was increased to accomodate the F-404 better.

PV-3 had the gap and it flies with the F-404-F2J3

LSP-2 had the gap and it too flew with the F-404-F2J3

LSP-3 (KH2013) has the same gap and it flew with the F-404-IN20..so we can guess that its not the increased length of the IN20 over the F2J3 that may have caused that gap.

And the relative position of the air brake with respect to the rudder line seems exactly the same as it is for LSP-7..a 1.5 ft increase would've been noticeable.

So I don't believe that the length of the LSP-7 has been increased since that is a major change and there is no real evidence that points to any length increase. There have been aerodynamic refinements done for sure such as the refining of that abrupt edge near the aft wing root, but doesn't seem like its a length increase.

ArmenT · Post by **ArmenT** » 12 Mar 2012 12:12

You know what, I thought LCA's tail numbering scheme was KH-XXXX where KH = Dr. Kota Harinarayana and the XXXX = the year of first flight (i.e. KH-2001, KH-2003, KH-2004 etc.). How come the latest bird says KH-2017. Did they change the numbering scheme or did they expect it to fly in 2017 when they first painted on the tail #?

Sid · Post by **Sid** » 12 Mar 2012 12:12

Early model LCA used to have 4 vents just ahead of engine exhausts.

These vents were smoothed out in later model. Maybe to compensate for those vents, this space was left out.

kmkraoind · Post by **kmkraoind** » 12 Mar 2012 13:01

Does the air goes from air brake vents to cool the engine? and let the loop complete with opening with the gap, if so, why only upper half of engine.

suryag · Post by **suryag** » 12 Mar 2012 13:25

Flight test update

LCA-Tejas has completed 1795 Test Flights successfully. (09-Mar-2012).
(TD1-233,TD2-305,PV1-242,PV2-215,PV3-334,LSP1-69,LSP2-200,PV5-36,LSP3-46,LSP4-46,LSP5-68,LSP7-1)

from

LCA-Tejas has completed 1790 Test Flights successfully. (06-Mar-2012).
(TD1-233,TD2-305,PV1-242,PV2-214,PV3-333,LSP1-69,LSP2-199,PV5-36,LSP3-46,LSP4-46,LSP5-67)

shiv · Post by **shiv** » 12 Mar 2012 14:32

Question: Do the grey areas have avionics?
http://2.bp.blogspot.com/-rMlqq_B9Hj4/T ... 0/lap3.JPG

Lalmohan · Post by **Lalmohan** » 12 Mar 2012 14:44

yes in some cases, though aren't the greys composite panels?

Gurneesh · Post by **Gurneesh** » 12 Mar 2012 20:33

carbon fiber is usually black. Those look like unpainted metal alloy panels (more evident in the larger pic of static side view). Must be the stuff that they changed after it had already been painted with primer.

Nikhil T · Post by **Nikhil T** » 12 Mar 2012 22:31

LCA Navy runs into trouble with CEMILAC: Ottawa News Reporter

One of the variants of India’s new fighter aircraft is running into some problems. The Guardian newspaper is reporting that the naval version of India’s first indigenous fighter — the Light Combat Aircraft (LCA-Navy) — has not been able to obtain the certification needed to make its debut flight because of structural issues.

More from the Guardian:
The Centre for Military Airworthiness and Certification (CEMILAC) refused the certification saying the structure of the aircraft needed rectifications. The debut flight was initially slated to take place by the end of 2010, but was delayed. The US Navy and the European consortium, EADS, are being consulted to rectify the problems.

The two most important features that require rectifications are the landing gear and special controls. The weight of the landing gear needs to be reduced. The movement of the Levcon (leading edge vortex control) too has to be reduced. A Levcon is a small wing ahead of the main wing of the aircraft, at the edge, and is required to have a controlled movement. These features distinguish the naval version from the Indian Air Force’s LCA.

Edit: Adding the referenced Sunday Guardian link.

SidSom · Post by **SidSom** » 13 Mar 2012 08:11

^^^ Does this mean that the News Tarmak007 promised will be significantly delayed......

PratikDas · Post by **PratikDas** » 13 Mar 2012 08:19

Nikhil T wrote:LCA Navy runs into trouble with CEMILAC: Ottawa News Reporter

Edit: Adding the referenced Sunday Guardian link.

Isn't it amusing that the LCA finds mention in popular media in lands far and wide all of a sudden? Typical

.

andy B · Post by **andy B** » 13 Mar 2012 09:27

Saar, one quick question onlee….IIRC Tejas has something like 45% to 50% composite use in its overall bodywork/panels. So if the composite usage is so high then do the composites get painted in the yellow primer as well???? I realize that the dielectric panels always have that grayish color just not sure what specific color if any the composite panels have….

P.S on successful flight of NP1 I put forth a proposal to have a lal chix display in GDF (do note however that this may need to be sneaked behind the back of nefarious Bengali breaperi.)

Kailash · Post by **Kailash** » 13 Mar 2012 11:47

andy B wrote:Saar, one quick question onlee….IIRC Tejas has something like 45% to 50% composite use in its overall bodywork/panels. So if the composite usage is so high then do the composites get painted in the yellow primer as well???? I realize that the dielectric panels always have that grayish color just not sure what specific color if any the composite panels have….

++1 to that. Surface composite cover should be way above 40-50% per claims. Also are composite also fastened using rivets? could still see a plenty of them on the skin.

prabhug · Post by **prabhug** » 13 Mar 2012 12:10

PratikDas wrote:
Nikhil T wrote:LCA Navy runs into trouble with CEMILAC: Ottawa News Reporter

Edit: Adding the referenced Sunday Guardian link.
Isn't it amusing that the LCA finds mention in popular media in lands far and wide all of a sudden? Typical .

"First they ignore you, then they laugh at you, then they fight you, then you win."
- Mahatma Gandhi

suryag · Post by **suryag** » 13 Mar 2012 12:37

yepp if they are talking about you(even if they are dissing you), it means you are worth talking about

suryag · Post by **suryag** » 13 Mar 2012 14:17

Flight test update

LCA-Tejas has completed 1796 Test Flights successfully. (12-Mar-2012).
(TD1-233,TD2-305,PV1-242,PV2-215,PV3-334,LSP1-69,LSP2-200,PV5-36,LSP3-46,LSP4-46,LSP5-69,LSP7-1)

from

LCA-Tejas has completed 1795 Test Flights successfully. (09-Mar-2012).
(TD1-233,TD2-305,PV1-242,PV2-215,PV3-334,LSP1-69,LSP2-200,PV5-36,LSP3-46,LSP4-46,LSP5-68,LSP7-1)

vina · Post by **vina** » 13 Mar 2012 16:06

Can someone who is good with photoshop/whatever post a plan view (ie view from top) and side view of the TD and LSP/PV next to each other, ie, the plan view of TD next to plan view of LSP and same for side view (preserving scale of original dimensions etc). Or better still, if you can overlap the two (ie plan of LSP on plan of TD and side view of LSP and side view of TD).

It will be good to see what the changes are. Obviously, there is a "plug" in the TD vs LSP in the rear. It will be good to see what other changes were there. Obviously, the LSPs incorporate the improvements /learnings from the TD program. The engine is obviously further to the rear in the LSPs over the TD and would have needed control law changes , which were obviously made/developed and I wonder what else. I am willing to bet the LSPs have greater internal fuel than the TD (2300kg ?) . This and the other goodies packed in, could explain the increase in the empty weight to the current 6500kg from the TD stage I think. That is a good 800 to 1000 kg weight increase than earlier budget.

Dimensions wise, it does seem that the LSP is marginally longer ( 1 reckon by 0.5 to 0.75 m) than the TD.

andy B · Post by **andy B** » 13 Mar 2012 16:52

arrreee bhava...te bhag te bhag....chakka udala ki...shittya vajav shittya....enjoy onlee...

Data point...check out the helmet at the end not sure if thats the Dash kit from Elbit but looks pretty nifty onlee.

member_20163 · Post by **member_20163** » 13 Mar 2012 17:26

Awesome Andy - Fantastic - I am going to watch it over and over again... Thanks

Kanson · Post by **Kanson** » 13 Mar 2012 17:50

andy B wrote:Saar, one quick question onlee….IIRC Tejas has something like 45% to 50% composite use in its overall bodywork/panels. So if the composite usage is so high then do the composites get painted in the yellow primer as well???? I realize that the dielectric panels always have that grayish color just not sure what specific color if any the composite panels have….

We often hear this 45 - 50 figure for composite % used. Does it by weight, volume or surface area? It is by weight.

What is the figure for surface area in %? It is 90 & above.

At manufacturing site, these panels look grey/black, like the exposed area of LSP 7 without any primer.

Singha · Post by **Singha** » 13 Mar 2012 17:55

the aam pylons are very hefty now. could double rack a couple of AASM on each inshallah.

that split AC type thing behind the cockpit seat also looks new...OBOGS?

MN Kumar · Post by **MN Kumar** » 13 Mar 2012 18:47

Couple of questions from the video:

At 2:35 mnts is that a Cannon?
Can someone id the HMDS?

A very cool video. I saw it after take off around whitefield. The engine noise was quite different from regular LCA roars. This looked pretty smooth.

prabhug · Post by **prabhug** » 13 Mar 2012 19:08

Can somebody comment on the length taken to take off on the LSP7 ? I see some confidence with pilot not checking lot of things as in the previous ones.

Kartik · Post by **Kartik** » 13 Mar 2012 19:32

That is the Gsh-23 cannon and the HMDS is the Elbit DASH