LCA news and discussion

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Re: LCA news and discussion

Postby Natt » 16 Feb 2010 14:55

putnanja wrote:
sohamn wrote:That's because the pilot in the naval LCA need better forward visibility while landing and take off from an aircraft carrier.


What will the additional space behind the pilot in N-LCA be used for? additional fuel? The image on Shiv Arror's blog has lot of space behind the pilot

The space will indeed be used for additional fuel and some avionics.
Here s an excerpt form ajai shukla's blog.
"The twin-seat Tejas is also important for the Indian Navy. The naval version of the Tejas, which will operate off aircraft carriers, will be based on the Tejas trainer; it’s higher cockpit allows the pilot a view of the carrier landing deck while descending steeply to land. In the naval Tejas there is no second cockpit; its place is taken by an extra fuel tank and some avionics."

http://ajaishukla.blogspot.com/2009/11/ ... ainer.html

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Re: LCA news and discussion

Postby KrishG » 17 Feb 2010 22:24


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Re: LCA news and discussion

Postby Craig Alpert » 17 Feb 2010 23:21

^^ Space can hold roughly ~ 400-500 t/r m's!

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Re: LCA news and discussion

Postby SaiK » 17 Feb 2010 23:33

they may have to use conformal to either side of LCA for another 200 odd each. Still does not cross 700-800 t/rs.

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Re: LCA news and discussion

Postby NRao » 17 Feb 2010 23:46

Craig Alpert wrote:^^ Space can hold roughly ~ 400-500 t/r m's!


Approx 578 slots.
Last edited by NRao on 18 Feb 2010 10:20, edited 1 time in total.

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Re: LCA news and discussion

Postby suraj p » 18 Feb 2010 00:50

mukul_chou wrote:
Rahul M wrote:mukul, the LCA has "no" air intake in that configuration, I wonder how the engine works ! :lol:

on a more serious note, the scoop is blocked, you won't want a little birdie to make it its home would you ?

Thanks for your info. I always believed that is not an air intake until I see this
http://i843.photobucket.com/albums/zz352/20enlightened1/d5751392.jpg


Image
that pic is from Ajai Shukla's LCA page. Take a look at the intake with LCA's gluteus maximus and latissimus dorsi exposed.

Will that in-take be a preparation for new engine configurations! (except that the new engine is not decided)

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Re: LCA news and discussion

Postby negi » 18 Feb 2010 01:13

Its a slotted array and slots != T/R modules on an AESA .

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Re: LCA news and discussion

Postby Craig Alpert » 18 Feb 2010 02:17

negi wrote:Its a slotted array and slots != T/R modules on an AESA .

I stand correced. My apologies for the blunder :oops:
Any guesses on how many t/r modules can they achieve on MKII using an ASEA with the same Radii??

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Re: LCA news and discussion

Postby sanjaykumar » 18 Feb 2010 02:27

That is one impressive beast.

Interesting that there are so many engineering types represented by females in India. Much more so than in the West (other than Russia).

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Re: LCA news and discussion

Postby k prasad » 18 Feb 2010 03:01

Craig Alpert wrote:
negi wrote:Its a slotted array and slots != T/R modules on an AESA .

I stand correced. My apologies for the blunder :oops:
Any guesses on how many t/r modules can they achieve on MKII using an ASEA with the same Radii??


Yes.... MMR is not an AESA, but as Negi mentioned, a slotted waveguide array.

although I need to mention here that the slotted waveguide antenna itself need not mean that its not an AESA. If you look at our AEW&C, it uses a slotted antenna, where the feeds come from & go to the TRMs. Note that these TRMs are quite large & heavy (abt 1 kg each).

However, the US have made their AESAs much smaller thanks to their superior MMIC technology, which makes the brick type TRMs redundant, and allows all the TRM parts to be fit into a really tiny tile that fits on the front of the panel. They used bricks only on their 1st gen AESAs. Read Carlo Kopp's analysis of the Zhuk AE for a great analysis of this stuff. But yes, we are at least 10-15 yrs behind the Khan AESA technology, but that doesn't mean we can't get the same radar performance with the older gen tech.

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Re: LCA news and discussion

Postby Khalsa » 18 Feb 2010 04:47

I don't think anyone seriously answered this but what is duct at the base of the tail fin used for ?

Image

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Re: LCA news and discussion

Postby jimit » 18 Feb 2010 05:46

Khalsa wrote:I don't think anyone seriously answered this but what is duct at the base of the tail fin used for ?

Image


I think it is for APU

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Re: LCA news and discussion

Postby Khalsa » 18 Feb 2010 07:15

Thank you

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Re: LCA news and discussion

Postby karan_mc » 18 Feb 2010 07:20

Image

what are this white patches on the wing surface of the tejas ? hope the paint is not getting ripped off

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Re: LCA news and discussion

Postby shiv » 18 Feb 2010 08:41

karan_mc wrote:Image

what are this white patches on the wing surface of the tejas ? hope the paint is not getting ripped off


Not sure why you hope that it's not paint getting ripped off. Paint can get ripped off and would call for repainting.

However I am guessing that this is not paint because it is the only picture that shows this among hundreds of photos and live sightings of these aircraft - of which there are only a handful. I suspect it is reflections of the sun from areas of the plane in a digital image that has been taken with the sun above and in front (and to the left) of the camera - for which the camera has either compensated for the brightness of the sky or the photo has been retouched digitally.

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Re: LCA news and discussion

Postby marimuthu » 18 Feb 2010 08:55

karan_mc wrote:what are this white patches on the wing surface of the tejas ? hope the paint is not getting ripped off


This flight has been instrumented to study the aerodynamic and stress datas

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Re: LCA news and discussion

Postby Cain Marko » 18 Feb 2010 09:17

Craig Alpert wrote:
negi wrote:Its a slotted array and slots != T/R modules on an AESA .

I stand correced. My apologies for the blunder :oops:
Any guesses on how many t/r modules can they achieve on MKII using an ASEA with the same Radii??



AFAIK, the late BHarry did mention that the nose of the Tejas was a bit on the large size. IIRC, an array of 650-700mm could find its way there. That would be larger than the Solah, Gripen and Rafale. Of course, cooling requirements and constricted space might mean smaller AESA for Tejas.

CM

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Re: LCA news and discussion

Postby Venu » 18 Feb 2010 09:35

karan_mc wrote:what are this white patches on the wing surface of the tejas ? hope the paint is not getting ripped off


Perhaps, someone has pasted the wall poster of a latest movie starring Puneet or arvind on its wings. After all, HAL engineers are also movie going fans :wink:

On a serious note, if you look at the pacth patterns, they can be observed along the edges of the wings.

IIRC, There is a tejas which has red tapes sticked all over its wings to study aerodynamic and stress data.( as here)

Patches might have been created when these tapes were removed peeling the paint off with them.

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Re: LCA news and discussion

Postby steve » 21 Feb 2010 16:13

Image
Image

Guys take a look at the above LCA Specifications (especially Dry Weight) AT HAL stall as part of DEFECE EXPO 2010 which is running now in New Delhi.The Dry Weight of LCA has gone down from 6500 KG ( figure given at AERO INDIA 2009 to 5680 kg now at DEFECE EXPO 2010) . Did they do some thing to bring down the LCA's dry weight?

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Re: LCA news and discussion

Postby vina » 21 Feb 2010 17:55

steve wrote:Guys take a look at the above LCA Specifications (especially Dry Weight) AT HAL stall as part of DEFECE EXPO 2010 which is running now in New Delhi.The Dry Weight of LCA has gone down from 6500 KG ( figure given at AERO INDIA 2009 to 5680 kg now at DEFECE EXPO 2010) . Did they do some thing to bring down the LCA's dry weight?


Yawn.. Zimble onlee. Old brouchure being shown at DefExPo 2010. The new super duper hot shot fresh off the oven Tejas will be around 6500kg dry weight onree.

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Re: LCA news and discussion

Postby jamwal » 21 Feb 2010 18:55

Image

This picture I took in IITF 2009 of LCA display in HAL section. Empty weight is 5685 KG.
Take off and landing distances in both displays are different though. 1700m and 1300m? :?:


The black/transparent pod in background is EL-8251 Escort Jammer Pod in IAI stall. I'll upload the picture soon
Last edited by jamwal on 21 Feb 2010 20:37, edited 1 time in total.

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Re: LCA news and discussion

Postby SaiK » 21 Feb 2010 19:34

shiv wrote:
karan_mc wrote:http://beta.thehindu.com/multimedia/dyn ... 29102g.jpg

What are this white patches on the wing surface of the tejas ? hope the paint is not getting ripped off
.. it is reflections of the sun from areas of the plane in a digital image that has been taken with the sun above .. retouched digitally.

Could it be another angle to the surface quality factor? :mrgreen:

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Re: LCA news and discussion

Postby Bheem » 21 Feb 2010 20:28

Incidentally LCA Mark-2 pics have not surfaced in this Def Expo!!!!!!!!!!!!!

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Re: LCA news and discussion

Postby jamwal » 21 Feb 2010 20:36

http://4.bp.blogspot.com/_Dc2Wx4jR9F8/S ... MG2802.JPG

and

http://1.bp.blogspot.com/_Dc2Wx4jR9F8/S ... MG2801.JPG

EL-2851 Pods
Can this be used on LCA or any other plane in Indian inventory ?

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Re: LCA news and discussion

Postby Wickberg » 21 Feb 2010 20:39

jamwal wrote:http://1.bp.blogspot.com/_Dc2Wx4jR9F8/SxKldW3HK_I/AAAAAAAAAoU/nNbiDdLtOcA/s1600/Image050.jpg[/img]

This picture I took in IITF 2009 of LCA display in HAL section. Empty weight is 5685 KG.
Take off and landing distances are different though. 1700m and 1300m? :?:


The black/transparent pod in background is EL-8251 Escort Jammer Pod in IAI stall. I'll upload the picture soon


It´s not just the landing and take off distances that looks very unimpressive. How are you suppose to make a naval LCA with such a long take off? Is the combat radius just 300 km?! That´s even below MiG-21 capability...
Last edited by Rahul M on 21 Feb 2010 22:26, edited 1 time in total.
Reason: don't quote posts with images.

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Re: LCA news and discussion

Postby shiv » 21 Feb 2010 21:40

SaiK wrote:Could it be another angle to the surface quality factor? :mrgreen:



Yes. This is exactly what I thought.

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Re: LCA news and discussion

Postby jamwal » 21 Feb 2010 22:00

Takeoff distance in this pic is 1300m

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Re: LCA news and discussion

Postby putnanja » 21 Feb 2010 22:24

Take off distance is more because the aircraft is more heavily loaded with fuel and weapons. When landing, the fuel would be spent, so the landing distance is less.

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Re: LCA news and discussion

Postby Rahul M » 21 Feb 2010 22:27

Wickberg wrote:It´s not just the landing and take off distances that looks very unimpressive. How are you suppose to make a naval LCA with such a long take off? Is the combat radius just 300 km?! That´s even below MiG-21 capability...

pretty sure those figures are with full combat load, not just a couple of token A2A missiles which is what most aircraft brochures show.

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Re: LCA news and discussion

Postby sohamn » 21 Feb 2010 22:29

Even with full combat load 300kms is too short. The figures that are shown makes it look quite inferior.

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Re: LCA news and discussion

Postby Jagan » 21 Feb 2010 22:32

putnanja wrote:How are you suppose to make a naval LCA with such a long take off?


Isnt that for "On the ground"?

On a carrier at full steam into the wind, the run should be shorter. though not short enough for unassisted TO's I would guess.

With a catapult launch it should be doable.

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Re: LCA news and discussion

Postby putnanja » 21 Feb 2010 22:33

Jagan, you quoted my name, but it wasn't me who made that statement :)

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Re: LCA news and discussion

Postby Rahul M » 21 Feb 2010 22:36

Jagan wrote:
putnanja wrote:How are you suppose to make a naval LCA with such a long take off?


Isnt that for "On the ground"?

On a carrier at full steam into the wind, the run should be shorter. though not short enough for unassisted TO's I would guess.

With a catapult launch it should be doable.

ski-ramp.

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Re: LCA news and discussion

Postby Rahul M » 21 Feb 2010 22:37

sohamn wrote:Even with full combat load 300kms is too short. The figures that are shown makes it look quite inferior.

how so ? you have the figures for other fighters ?

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Re: LCA news and discussion

Postby Rahul M » 21 Feb 2010 22:43

for those interested in an aerodynamic analysis of the LCA's range/payload performance.

http://mach-five.blogspot.com/search?up ... -results=7

scroll down to the bottom of the page for the april 12 entry.
Image

Image

Image

Image

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Re: LCA news and discussion

Postby Wickberg » 21 Feb 2010 22:52

Rahul M wrote:
sohamn wrote:Even with full combat load 300kms is too short. The figures that are shown makes it look quite inferior.

how so ? you have the figures for other fighters ?


Well, LCA is often compared to another light weight fighter, the Gripen. The A/B/C/D version of that has a combat radius of 800 km, the Gripen NG have one that is +1300 km. So compared to those numbers 300 km seems a bit strange....

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Re: LCA news and discussion

Postby Wickberg » 21 Feb 2010 22:57

Rahul M wrote:ski-ramp.



Still, 1700 meters seems very long, most fighters can take off fully loaded within 1000 meters. I´ve seen a fully loaded Gripen taking off in 400 meters on a road base. 1700 meters is what a large commercial jet needs when it´s carrying tourists to Thailand. The numbers on that fact sheet must be totally wrong...

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Re: LCA news and discussion

Postby Kartik » 21 Feb 2010 23:43

Cain Marko wrote:AFAIK, the late BHarry did mention that the nose of the Tejas was a bit on the large size. IIRC, an array of 650-700mm could find its way there. That would be larger than the Solah, Gripen and Rafale. Of course, cooling requirements and constricted space might mean smaller AESA for Tejas.

CM


CM, the nose diameter is 650mm..unless you manage to push the antenna really far behind (and that is difficult on the LCA because there is very little space behind the radome) you won't be able to fit a 650mm antenna itself. My guess would be a 600-625 mm antenna diameter depending on how much the size of the back-end instruments will be.

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Re: LCA news and discussion

Postby Rahul M » 21 Feb 2010 23:52

Well, LCA is often compared to another light weight fighter, the Gripen. The A/B/C/D version of that has a combat radius of 800 km, the Gripen NG have one that is +1300 km. So compared to those numbers 300 km seems a bit strange....
combat radius of 800 km with what load-out and flight profile ? if you have the details I'll be very thankful.

The numbers on that fact sheet must be totally wrong...
the numbers do look very iffy to me, especially with no details available. but who am I to argue with OEM info-boards, assuming it is one.

btw, the graphics I've posted above is from an aero engn whose work is very reliable, the figures are within 10% of actual ones, usually much less.

check this out for landing distance. this is the first flight back in 2001, the take-off run starts at 2:34 and it is airborne by 2:52, in 18 seconds.
assuming 220 kmph to be the take-off speed (typical of fighters) 110 kmph (30.55 m/s) is the avg speed in take-off run the take-off distance comes to about 550 metres.
[youtube]njjABo08KCM&feature=PlayList&p=097D08329CD6A3DB&playnext=1&playnext_from=PL&index=1[/youtube]

btw, they have LERX planned for the NLCA to reduce take-off and landing speeds.

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Re: LCA news and discussion

Postby Wickberg » 22 Feb 2010 00:12

Rahul M wrote:
combat radius of 800 km with what load-out and flight profile ? if you have the details I'll be very thankful.

the numbers do look very iffy to me, especially with no details available. but who am I to argue with OEM info-boards, assuming it is one.

btw, the graphics I've posted above is from an aero engn whose work is very reliable, the figures are within 10% of actual ones, usually much less.

check this out for landing distance. this is the first flight back in 2001, the take-off run starts at 2:34 and it is airborne by 2:52, in 18 seconds.
assuming 275 kmph to be the take-off speed (typical of fighters) and 250 kmph to be the avg speed in take-off run (which estimate is firmly on the higher side, for the acceleration on the first flight is positively 'easy going'. but let's ignore that) the take-off distance comes to about 1250 metres. the actual distance should be lower, I don't see how it can be higher as given in the info-board. strange indeed.

btw, they have LERX planned for the NLCA to reduce take-off and landing speeds.


The loadout is 2 RBS-15, 2 Mavericks, 2 Sidewinders and a central tank. Fully loaded, the flight profile is low-low-low. It has always been an requirement for Swedish fighters to be able to attack harbors in the Baltic, flying as low as possible to avoid radar as long as possible. Back in the days of the cold war the official radius numbers for the Viggen/Draken/Lansen etc were reduced because the Swedish Airforce did´nt want Sovietunion how far the aircrafts could actually reach. After 1991 the real numbers were released, it was actually up to 25% higher then what SAAB had told the public.

A take off distance of 1250 meters is still a lot for a fighter. Compare that video to this of a Gripen landing/taking off from a road base...

http://www.youtube.com/watch?v=QJQKCUjcslM


Edit: The flight profile may be low-low-high


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