Tejas Mk.2: News & Discussions - 25 February 2018

John
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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby John » 27 Mar 2018 07:53

SaiK wrote:From Mk1 dhaaga:

MTOW : 16,200 kg (35,715 lbs)
Uttam : Design is complete. Next month testing a previous version of the indigenous radar.

Any word on Empty weight?

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby SaiK » 27 Mar 2018 08:24

You have to decipher from:

It will carry a more powerful engine and weigh almost 20 per cent heavier than Tejas
.

Around 7,500 kgs perhaps.[WAG]

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Indranil » 27 Mar 2018 11:19

That MTOW number is not even close ;-). If they increase thrust by 10%, can't see how they will increase the clean take off weight by more than 10%. So that's roughly 1 more ton. Even if they increase payload by 1 ton, that brings MTOW to 15,500 kgs. I think MTOW will be closer to 15 Tons.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Singha » 27 Mar 2018 11:38

how agile do people think the rafale will be in this config ?
Image

the EF tried to demo its chutzpah in a similar config in farnborough 2010 and was constantly using afterburners to get its turns going...not sustainable

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby JayS » 27 Mar 2018 12:18

Indranil wrote:That MTOW number is not even close ;-). If they increase thrust by 10%, can't see how they will increase the clean take off weight by more than 10%. So that's roughly 1 more ton. Even if they increase payload by 1 ton, that brings MTOW to 15,500 kgs. I think MTOW will be closer to 15 Tons.


NLCA MK2 was to have 16.5T MTOW, as per what I was told in AI-2017. AF version can also have MTOW in the ballpark. We know it can lift quite a bit. Obviously performance would take a hit in fully loaded condition and full MTOW may not be possible from all airfields and under all the conditions, and would not be needed for majority of the use cases, but that should not stop them from certifying MK2 for higher MTOW. For once they will have good brochure figures. :wink:

Its one of my pet wish to see MK2 certified for 5T max load out. :mrgreen:

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Singha » 27 Mar 2018 12:30

I think for tier1 static targets SAAW with dual and triple rack will pack the punch of the aasm/sdb type weapons, backed up with heavier warheads and range of garuda and garudamma for bigger SAM bubbles.

lesser static targets and moving targets of opportunity will merit CCIP bombs and LGBs

with accuracy improving , the need for large 2000lb will be a niche meant for deeply buried targets.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby kit » 27 Mar 2018 13:27

Apparently, the UTTAM is a scaleable beam radar similar to the NORTHROP GRUMMAN SABR meaning it can be modified and upgraded (more TRMs increased range) to fit different platforms .. hugely significant for Indian military

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Indranil » 27 Mar 2018 14:50

JayS wrote:
Indranil wrote:That MTOW number is not even close ;-). If they increase thrust by 10%, can't see how they will increase the clean take off weight by more than 10%. So that's roughly 1 more ton. Even if they increase payload by 1 ton, that brings MTOW to 15,500 kgs. I think MTOW will be closer to 15 Tons.


NLCA MK2 was to have 16.5T MTOW, as per what I was told in AI-2017. AF version can also have MTOW in the ballpark. We know it can lift quite a bit. Obviously performance would take a hit in fully loaded condition and full MTOW may not be possible from all airfields and under all the conditions, and would not be needed for majority of the use cases, but that should not stop them from certifying MK2 for higher MTOW. For once they will have good brochure figures. :wink:

Its one of my pet wish to see MK2 certified for 5T max load out. :mrgreen:

I expect empty weight to be around 7 to 7.2 tons. Clean take off weight to be around 10.5 tons. Even with 5 tons of payload, you would have an MTOW of 15.5 tons.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby JayS » 27 Mar 2018 15:42

Indranil wrote:
JayS wrote:
NLCA MK2 was to have 16.5T MTOW, as per what I was told in AI-2017. AF version can also have MTOW in the ballpark. We know it can lift quite a bit. Obviously performance would take a hit in fully loaded condition and full MTOW may not be possible from all airfields and under all the conditions, and would not be needed for majority of the use cases, but that should not stop them from certifying MK2 for higher MTOW. For once they will have good brochure figures. :wink:

Its one of my pet wish to see MK2 certified for 5T max load out. :mrgreen:

I expect empty weight to be around 7 to 7.2 tons. Clean take off weight to be around 10.5 tons. Even with 5 tons of payload, you would have an MTOW of 15.5 tons.


with say 7.2T empty weight, clean TO weight should be around 11T no..? as of now its 9800kg. Adding 700kg fuel, and some weight gain on airframe, it should go close to 11T, I think. So 16T MTOW possible, give of take some..?

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby SaiK » 27 Mar 2018 17:42

Singha ji, they improved the agility by adding the LERX later in 2013.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby sohamn » 27 Mar 2018 23:01

SaiK wrote:Singha ji, they improved the agility by adding the LERX later in 2013.


If Tejas goes full ethernet in its network interface then they can shave few hundred kilos in weight. Turns out that copper wires are one of the heaviest individual components in an aircraft. Not sure, why ADA is not thinking of an Ethernet-based network akin to AFDX

https://en.wikipedia.org/wiki/Avionics_Full-Duplex_Switched_Ethernet

Ethernet will also improve reliability and easier detection of fault and ease of maintenance. And the best part is that everyone knows ethernet based network so tech skills are easily available. So this same reason, automobiles are completely switching to Ethernet-based networks instead of CAN or LIN or FlexRay.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Haridas » 28 Mar 2018 08:45

^^^ Contrast Ethernet versus MIL-STD-1553:::: Dhara aur Kshitij kaa antar

Copper wire based MIL-STD-1553 signalling has given way to Fiber optic based communication MIL-STD-1773 that has multitudes of other advantages including EMP.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Neshant » 28 Mar 2018 13:20

Differential signalling on copper lines has reasonable noise immunity - though its slow.
It takes quite a lot to damage a copper line physically to a point the signal no longer gets through.
Not sure how robust fiber optic lines are in a military system.

They are fast and light weight, no doubt and perfect for video based applications with multiple, heavy data feeds.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Singha » 28 Mar 2018 13:40

i think not just bandwidth and weight saving, but a single fiber can replace many bundles of individual copper cables.

a commercial plane using copper wires would be 10-20km of cable for sure
Image

like this
Image

using limited runs of fiber it might be possible to have more protection in a fighter than masses of copper wires all over.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Bart S » 28 Mar 2018 16:43

Neshant wrote:Differential signalling on copper lines has reasonable noise immunity - though its slow.
It takes quite a lot to damage a copper line physically to a point the signal no longer gets through.
Not sure how robust fiber optic lines are in a military system.

They are fast and light weight, no doubt and perfect for video based applications with multiple, heavy data feeds.


Other than the bend radius needing to be respected, there is no other real issue with fiber reliability vis a vis copper. In fact a lot of commercially available fiber cables are designed with a lot more toughness built in than the average copper cable, there are cables that are heat/water resistant, rodent bite resistant, designed for being laid directly in the ground without a protective conduit for outdoor applications, etc.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Dileep » 28 Mar 2018 18:23

There will be fiber optics on MK2, way beyond what you imagine.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby shiv » 28 Mar 2018 19:17

Dileep wrote:There will be fiber optics on MK2, way beyond what you imagine.

Hmmm Dileep. That's interesting - if I read between the lines

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Zynda » 28 Mar 2018 20:13

Probably FBL among other things...also I would think there would be reduction in wire bundle/harness thickness going from Copper to Fiber...it may be small but probably significant for a small aircraft like Tejas. Along with better positioning of LRUs/Electronic bay racks in Mk.2 fuselage for accessibility, space management should see some improvement.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby suryag » 28 Mar 2018 20:51

Dileep sir for long I have been thinking about applicability of FBWireless, did quite a lot of study on available literature on applicability to aircrafts and give my own long background on wireless I believe it can be done, what am I missing here ?

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby pravula » 28 Mar 2018 21:03

suryag wrote:Dileep sir for long I have been thinking about applicability of FBWireless, did quite a lot of study on available literature on applicability to aircrafts and give my own long background on wireless I believe it can be done, what am I missing here ?


lag, jamming

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby srin » 28 Mar 2018 21:04

Would FBL be lighter than FBW and help Tejas shed some weight ?

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby suryag » 28 Mar 2018 21:06

What if someone guarantees lag and against jamming ? One thing possibly is that the radios inside the airframe need to operate at -60c and possibly at 80c this Tamb leads to Tjunc numbers that have not been achieved with CMOS till date, is that the reason ?

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Singha » 28 Mar 2018 21:29

perhaps interference from offensive and defensive EW RF equipment like that garpun bal radar interfering with the radio command link of shtil missiles?

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby suryag » 28 Mar 2018 21:39

SIngha sir the airframe could have a thin wrap of active shielding material(ala faraday cages). This FBWi would be for all sensors actuators within the airframe I.e., we are creating a small femto cell network. External RF comms should be unaffected.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Singha » 28 Mar 2018 22:51

some details why its not considered yet

https://aviation.stackexchange.com/ques ... -practical

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby sohamn » 28 Mar 2018 23:05

The biggest benefit comes in developing a network like a LAN based ethernet, where one single cable runs across the aircraft ( with a backup / redundant LAN also available ). Every single device has an IP and the LAN also has a switch that helps connect the devices and a router that can help communicate with other fighters nearby. This architecture would have the biggest benefit since the current coax/copper cable requires a hub and spoke architecture where everything including the FBW is connected to the central computing unit and hence the current architecture is very heavy.

Typically the average weight of automotive cabling is around 100 kg ref http://theinstitute.ieee.org/resources/standards/fewer-wires-lighter-cars

And via the use of Ethernet in vehicles there are approximate weight savings of around 30 kgs. So just imagine for an aircraft it would be much more since there is quadruple redundancy in most fighter jets and cabling is much more complex.

More details on the automotive internet can be found here - https://support.ixiacom.com/sites/defau ... aper_1.pdf

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby pravula » 28 Mar 2018 23:45

Now-a-days ethernet is hub/spoke by defn. There is no single cable that every one plugs into / splices. There used to be an old wired protocol that would let you use one single cable, but it was highly inefficient (you basically get all the drawbacks of a wireless connection and drawbacks of wired too)

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Eric Leiderman » 29 Mar 2018 00:09

Singha wrote:some details why its not considered yet

https://aviation.stackexchange.com/ques ... -practical


Just a noob question, With quadriple fly by wire why can't one or two of them be wireless, where by you get the weight saving and the reliability of a wired system.

If system is jammed it shuts down and you have the back up of the wired system.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Kartik » 29 Mar 2018 01:44

Dileep wrote:There will be fiber optics on MK2, way beyond what you imagine.


Recall seeing that in earlier Tejas Mk2 proposals. Good to know that it is planned still.

The weight of the cabling on the on the Tejas is supposed to be ~400 kgs or so. If that could be reduced by a couple hundred kilos, it would be good for lowering the empty weight.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Dileep » 29 Mar 2018 06:09

There are multiple roles for fiber on board.
1. Data acquisition system
2. Mission and Display system
3. Fiber Optic Sensors
4. Flight control (the least priority)

1 and 2 will happen in MK2 most likely.

Apart from weight saving, there is space saving too. There is pretty little space to pull cables, and the operators need to literally bend over backwards to manage the cabling.

Fiber do have its disadvantage as well. The end to end reliability is often LOWER because of the optoelectronics at either end.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Singha » 29 Mar 2018 07:22

in the Mk1A thread it is said the Tejas has 40km of cables on board. thats a lot. weight savings will be big if they can combine the data carried by multiple cables .... because additional weight of the optical modules at both ends have to be +added ...
things have been getting smaller....back in 2012 the CFP on the left was as big as a cellphone and heavier in weight , now CFP4 is pretty small.

Image

there is also a "breakout" mode of operations. like you can use a 40Gbps optic module but have 4 octupus wires hanging out and connect 4 x 10Gbps at the other end. this is pretty routine now. same for 100->10x10. it was a rage a jasba for 40->4x10 and 100->10x10 back in 2012 when i was working in that area on new boards including "combo" boards like 100 + 40....because most customers could not fill a 40/100 pipe back in those days our long haul lines in india were at 10gbps (and in cheen 40gbps) so they wanted to split into bite size 10gbps chunks and use in different directions.

this one is fiber cable but there is also light blue colour copper variant.

Image

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Neshant » 29 Mar 2018 11:17

I doubt we are going to be seeing fiber optic bundles on MK2.
The electronics would have to be redesigned so the transceivers on LRUs can accommodate fiber optic signalling.
That means the electronics would have to be re-validated.
Its not difficult but the issue is TIME.

Maybe we will see a fiber optic network on board as an addition to the existing network. This is to enable high speed external payload interconnects that can be added later (e.g. recon payloads, FLIR.. etc).

AMCA might see a few fiber bundles if indeed it is to have automated 360 coverage & associated smarts.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Singha » 29 Mar 2018 11:29

each LRU expects to see electrical signals over copper wires. perhaps a special LRU could take a single fiber as Rx and split it all out into current copper electrical tx'es so that no other LRU will need to change.

it will ofcourse need retest.

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Haridas » 29 Mar 2018 20:55

suryag wrote:SIngha sir the airframe could have a thin wrap of active shielding material(ala faraday cages). This FBWi would be for all sensors actuators within the airframe I.e., we are creating a small femto cell network. External RF comms should be unaffected.

1. Wireless in lieu of cable will be disastrous because enemy will detect you first, it doesn't take much to sniff even a minor leak at freq > 10mhz. At GHz it's worse.
2. Faraday cage, you don't know how difficult it would be to engineer a military rated one that will leak not once and last 30 years. I hope you saw the recent pic of rough uneven panel on Mig21.


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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby ragupta » 29 Mar 2018 21:42



Excerpt:
"...The order for Mark 2 will be placed once HAL understands what all capabilities IAF wants in the aircraft..."

So IAF does not know what capabilities they want in LCA Mk2?

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby RoyG » 29 Mar 2018 22:05

ragupta wrote:


Excerpt:
"...The order for Mark 2 will be placed once HAL understands what all capabilities IAF wants in the aircraft..."

So IAF does not know what capabilities they want in LCA Mk2?


If you watch the interview of NS, you can clearly see that there is no vision to really build a homegrown and self sustaining MIC either at the top or by the airforce. It's a sad state of affairs. I can guarantee that there will be piecemeal orders overtime and we'll lag consistently behind the curve as global technology advances. As far as licence assembly goes, at least the gov has made it a more efficient process. I think her heart is in the right direction but it will take some time for the culture to change especially at HAL. She could barely hold in her anger :lol: .

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Haridas » 30 Mar 2018 11:14

ragupta wrote:


Excerpt:
"...The order for Mark 2 will be placed once HAL understands what all capabilities IAF wants in the aircraft..."

So IAF does not know what capabilities they want in LCA Mk2?

HAL is as skeptical of goal post move by IAF, (as IAF was of getting 3 legged cheetha from HAL), so want IAF to call out in writing. IMHO very fair and professional method/request

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Trikaal » 30 Mar 2018 11:58

Seriously, get IAF to write down all the requirements on a stamp paper now! Just Kidding. On a serious note, I don't see IAF shifting goalposts too much with Mk2 provided HAL meets the deadlines decided at the start of the project. Seriously, get HAL to write down their deadlines on a stamp paper too :rotfl:

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Re: Tejas Mk.2 News & Discussions: 25 February 2018

Postby Austin » 30 Mar 2018 12:00



When ever they quote sources and unnamed officials for defence related news , these news are just fake ones or lifafa , stop believing them if they are not quoting the name of offical


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