Tejas Mk.1 & Mk.1A: News & Discussions: 23 February 2019

[Kartik]

SP-21, 22, 23 and 24 to be delivered by March 2020 to No.18 ‘Flying Bullets’ squadron. Should see the re-raising of No.18 Squadron perhaps early next year with those 4 jets.

SP-25 to SP-36 to be delivered by March 2021. So the assembly line will be able to produce 12 Tejas jets in 2020-21 timeframe. Perhaps they may have additional capacity and may be assembling the Tejas Mk2 prototypes concurrently.

Indranil, Tejas Mk1A prototype will likely be a modified LSP Tejas Mk1, right? If the contract signature happens by this year end, should take about half a year for the modified Mk1A prototype to fly? That should be by end of 2020. I’m hoping there is no production lull since very high, almost 90% commonality exists between Mk1 and Mk1A. So the same line can continue to produce the fuselage and wings while the flight testing goes on to certificate the Mk1A.

[srai]

^^^
There’s also 8 LCA Mk1 Trainer FOC and another 8 or so Mk1 Trainers as part of 83 Mk1A deal. FOC for trainer variant was supposed to come through sometime by now. Comes to around 16 airframes for trainers.

[srai]

Great news about the gun ! I was under the impression it wasn't in the FOC. And hadn't heard any news of the air testing of the gun.

Gun wasn’t part of FOC. The integration effort is ongoing last we heard. IMO, probably 2-years away.

PV-3 -> ground firing ~2014/2015

LSP-7 -> ground firing ~2016/2017 [no news of firing in flight as of yet] It was imminent around June 2017 but news stopped after that point. Next development was that it wasn’t part of FOC.

[srin]

Great news about the gun ! I was under the impression it wasn't in the FOC. And hadn't heard any news of the air testing of the gun.

Gun wasn’t part of FOC. The integration effort is ongoing last we heard. IMO, probably 2-years away.

PV-3 -> ground firing ~2014/2015

LSP-7 -> ground firing ~2016/2017 [no news of firing in flight as of yet] It was imminent around June 2017 but news stopped after that point. Next development was that it wasn’t part of FOC.

So, the report posted in previous page is wrong ? Reposting from the link ...

Among the key features that have been added to improve the performance are: air-to-air refueling probe, Gsh-23 mm gun, pressure refueling with three drop tank configuration, integration of 725 and 450 liters of drop tank, improved wing navigation lamp, in-flight wind mill relight, tandem pylon and zoom climb to name a few.

[srai]

^^^
Lot of news is copy and paste stuff. Although AK is one of the reliable reporters, I wouldn’t just go by one news article. Let’s see if more news outlets report on it.

At this point not likely ... unless the LCA test team have been doing gun testing in secret ...

Also, that 450-liter external tank is news to me. Haven’t seen or heard of that one before. I mean there was a detailed study for a supersonic tank 450 liter vs 710 liter. The latter was the one chosen and displayed in the recent AeroIndia.

[Indranil]

Indranil, Tejas Mk1A prototype will likely be a modified LSP Tejas Mk1, right?

Correct

[nam]

Given that we have a LSP flying with Uttam, technically MK1A is already flying!

If Uttam get's it foot in the door instead of 2052, then the biggest pending item would SPJ (& Derby int with Uttam?) and the issues it might create with our radar. However that should not stop HAL from starting production, as SPJ will not effect the LCA structure.

We have a backup in Astra, if Derby becomes a problem.

[Picklu]

Gun wasn’t part of FOC. The integration effort is ongoing last we heard. IMO, probably 2-years away.

PV-3 -> ground firing ~2014/2015

LSP-7 -> ground firing ~2016/2017 [no news of firing in flight as of yet] It was imminent around June 2017 but news stopped after that point. Next development was that it wasn’t part of FOC.

So, the report posted in previous page is wrong ? Reposting from the link ...

Among the key features that have been added to improve the performance are: air-to-air refueling probe, Gsh-23 mm gun, pressure refueling with three drop tank configuration, integration of 725 and 450 liters of drop tank, improved wing navigation lamp, in-flight wind mill relight, tandem pylon and zoom climb to name a few.

Aero gurus can correct me if i am wrong but this (at around 6 min mark of the video) is a zoom climb & Tejas executed this in 2016 itself in Bahrain; the entire extended low level flight over runway was to gain kinetic energy for the climb

[Austin]

What is going on with the Indian Tejas?

https://hushkit.net/2019/09/19/what-is- ... ian-tejas/

[JayS]

^^Another opinion piece with half baked info.

[Cain Marko]

Where is the bigger order for the mk1 from the IAF? this is seriously aggravating.

Even now DRDO Director is hoping that the contract would be signed within this FY - which ends in March - full 6 months away. The RFP for Mk1A was issued in Dec 2017. Even if we sign the contract in March 2020, it will be 28 months to seal a contract. Ridiculous!

Every single thing in our defence moves at glacial speed.

No sir, I'm actually peeved that there were no extra orders for the mk1 itself - foc standard, not the mk1a. There is definitely room for additional 1-2 sqds.

[SaiK]

https://twitter.com/Amitraaz/status/117 ... 48865?s=19

Uttam on LSP2

[Prasad]

He's just rehashing what i said.

[Cain Marko]

Not sure if this was discussed here before or if this man's info is accurate but interesting bits include

Uttam has demonstrated detection of 1msq target at 105km but will be capable of up to 160km with more power.

Can track 100 targets simultaneously

Currently has about 750 trms.

https://youtu.be/Im2ajJtRSdE

There is also a little table that compares it to the rbe2 and klj series towards the end.

[JayS]

So, the report posted in previous page is wrong ? Reposting from the link ...

Aero gurus can correct me if i am wrong but this (at around 6 min mark of the video) is a zoom climb & Tejas executed this in 2016 itself in Bahrain; the entire extended low level flight over runway was to gain kinetic energy for the climb

That is indeed zoom climb. But Baharin Airshow performance was with a special FCS version which opened up the envelop more than what was certified for operation Jets at that time i.e. IOC. It would have been a work in progress that time and ADA/NFTC might have had enough confidence to go with it just for Airshows where very experienced TPs are executing a carefully orchestrated ballet.

But in operational usage zoom climb could be much more than this. The Pilot could go supersonic just after TO before starting the climb. This is useful for quickly reaching high altitude to intercept bandits for Operational Readiness jets.

Thinking allowed - The mode itself could have much more than what meets the eye. There could be tweaks needed to various systems so higher climb rate than the max rated steady climb rate can be executed without issues, e.g. Fuel and hydraulic system, Engine. The Engine FADEC could have a special mode with bumped up T4 for a short while to get slightly more thrust for fastest climb to altitude to reduce time to intercept high altitude flying aircrafts. The fuel system may need tweaks to manage fuel flow from various tanks properly.

[nam]

Seeing the Uttam reminds me of the Cope India 2004, where the Khan commenator kept saying, it was one side because the trump card of F15, it's AESA FCR was not used!

I could only wonder the amount of laugh it would have generated, if we said India will have it's own AESA FCR prototype, with it's own TRM ready for flight testing in 12 years!

And here we are. All done by a sarkari agency, which had been called every name under the sun.

[Picklu]

Aero gurus can correct me if i am wrong but this (at around 6 min mark of the video) is a zoom climb & Tejas executed this in 2016 itself in Bahrain; the entire extended low level flight over runway was to gain kinetic energy for the climb

That is indeed zoom climb. But Baharin Airshow performance was with a special FCS version which opened up the envelop more than what was certified for operation Jets at that time i.e. IOC. It would have been a work in progress that time and ADA/NFTC might have had enough confidence to go with it just for Airshows where very experienced TPs are executing a carefully orchestrated ballet.

But in operational usage zoom climb could be much more than this. The Pilot could go supersonic just after TO before starting the climb. This is useful for quickly reaching high altitude to intercept bandits for Operational Readiness jets.

Thinking allowed - The mode itself could have much more than what meets the eye. There could be tweaks needed to various systems so higher climb rate than the max rated steady climb rate can be executed without issues, e.g. Fuel and hydraulic system, Engine. The Engine FADEC could have a special mode with bumped up T4 for a short while to get slightly more thrust for fastest climb to altitude to reduce time to intercept high altitude flying aircrafts. The fuel system may need tweaks to manage fuel flow from various tanks properly.

Thanks JayS. Particularly the last paragraph is very illuminating, what makes it worthwhile to spend time on BRF.

[Indranil]

Jay,

Operationally, that scenario hardly ever arises. Imagine the TWR required to fly through Mach barrier while in a climb. And then at the end of the climb the fighter has to make a supersonic turn in the vertical plane.

Typically, the pilot would climb quickly, return to level flight at high altitude and then quickly go supersonic thereafter.

[Aditya_V]

Only way it makes sense is bogie is right above and give maximum momentum to the AAM to get the bogie at altitude

[nachiket]

Jay,

Operationally, that scenario hardly ever arises. Imagine the TWR required to fly through Mach barrier while in a climb. And then at the end of the climb the fighter has to make a supersonic turn in the vertical plane.

Jay mentioned going supersonic as quickly as possible after takeoff before starting the climb. But then the aircraft will bleed airspeed during the climb and not be flying supersonic by the time it reaches the desired altitude. Not sure how it helps. It would be much easier to accelerate to supersonic speed after climbing in the thinner air at a higher altitude than the dense air closer the the ground just after takeoff.

[Picklu]

My understanding is that gaining height using pure aerodynamics takes more time and that's where zoom climb comes into picture.

So the aircraft will go supersonic at low level immediately after take off and then use the higher speed and aerodynamics to gain height quickly. It will loose speed in the process but will be able to gain that back fast at the thinner air. The flight pattern would essentially be a sigmoid curve where the gain in speed happens in the initial and end horizontal portions of it. The vertical portion is steeper than whats possible purely by aerodynamics due to kinetic assist from the initial higher speed.

Would like to be corrected if I am wrong.

Also, another use case is to use zoom climb to go beyond the max ceiling which is not possible by pure aerodynamics. I understand U2 flights were challenged successfully in that manner by regular fighters.

[Karan M]

Not sure if this was discussed here before or if this man's info is accurate but interesting bits include

Am not sure where he got the 105 km claim from. There was a DRDO seminar where people were struggling to make out whether it was 115km or 105km or 150 km .. most likely the last. 150km vs 2 sq mtr is our std target.

[JayS]

Jay,

Operationally, that scenario hardly ever arises. Imagine the TWR required to fly through Mach barrier while in a climb. And then at the end of the climb the fighter has to make a supersonic turn in the vertical plane.

Jay mentioned going supersonic as quickly as possible after takeoff before starting the climb. But then the aircraft will bleed airspeed during the climb and not be flying supersonic by the time it reaches the desired altitude. Not sure how it helps. It would be much easier to accelerate to supersonic speed after climbing in the thinner air at a higher altitude than the dense air closer the the ground just after takeoff.

Correct. In zoom climb you trade off KE for PE to achieve higher climb rate than what can be achieved in sustained powered climb. Jet engines find it much easier to give max possible thrust at given altitude at lower altitudes than at higher altitudes. Hence one can extract max energy out of the engines at low altitude at higher rate and then trade it off for height in climb.

IR,

Vertical turn in supersonic flight should not be too difficult. it need not be 8-9G, but fighters are rated for 5-6G typically at supersonic speeds. Besides the plane will quickly lose speed to go subsonic again, but in those precious few seconds it would have climbed a few '000 ft easily. Also it will be useful for lightly loaded configurations only. Interception is the ideal one I feel.

Gripen has something called Tiger Start, which allows it to TO from -40C completely cold start within 90sec. I wonder if LCA has something like this too. Though we don't have a very pressing need to have such mode.

[JayS]

Not sure if this was discussed here before or if this man's info is accurate but interesting bits include

Am not sure where he got the 105 km claim from. There was a DRDO seminar where people were struggling to make out whether it was 115km or 105km or 150 km .. most likely the last. 150km vs 2 sq mtr is our std target.

Wa have Uttam Poster from Aero India saying 150km. But no target size mentioned, but likely 2m2 which is the standard for us, as you have mentioned.

[Kartik]

Since when did 2 m2 become the standard fighter target RCS? It was always 5 m2 earlier.

[Haridas]

Not sure if this was discussed here before or if this man's info is accurate but interesting bits include

Uttam has demonstrated detection of 1msq target at 105km but will be capable of up to 160km with more power.

Can track 100 targets simultaneously

Currently has about 750 trms.

https://youtu.be/Im2ajJtRSdE

There is also a little table that compares it to the rbe2 and klj series towards the end.

Significantly higher voltage GaN transistors are now becoming available that IMHO would increase TRM power output by 2 to 3 times. Thus the Uttam range will only continue to go up from where it is now.

With Uttam on LCA, there is pressing need for matching longer range AAM.

[sajaym]

So my understanding is that a ‘Zoom climb’ is a flight profile is used during special situations by pushing the aircraft to it near extremes. Such a flight profile might usually be flown by highly experienced pilots who are able to execute all the required actions to the T, to get the desired result. A regular pilot trying to execute this maneuver might not get the desired result at the desired moment – which would be disastrous. Hence, introducing the ‘Zoom Climb’ mode. Here now any pilot on an ORP takeoff just needs to press a button and the FCS executes the Zoom Climb to perfection, to give Pakis another kick ASS (Abhinandan Style Shootdown). Brilliant! Shows the extent to which we can innovate with homegrown products.

[Haridas]

So my understanding is that a ‘Zoom climb’ is a flight profile is used during special situations by pushing the aircraft to it near extremes. Such a flight profile might usually be flown by highly experienced pilots who are able to execute all the required actions to the T, to get the desired result. A regular pilot trying to execute this maneuver might not get the desired result at the desired moment – which would be disastrous. Hence, introducing the ‘Zoom Climb’ mode. Here now any pilot on an ORP takeoff just needs to press a button and the FCS executes the Zoom Climb to perfection, to give Pakis another kick ASS (Abhinandan Style Shootdown). Brilliant! Shows the extent to which we can innovate with homegrown products.

Well then why flat rate the engine?

[Aditya_V]

This Flat rating was a utopian concept which the IAF put to GTRE with people like Suresh Kalmadi, who then as Rajya Sabha member tried to get the LCA programme cancelled. People like him would have used their service period to get themselves networked in the Airforce/ Defence forces/ MOD eco systems- trying to undo what 99% of Defence forces are doing.

https://www.drdo.gov.in/drdo/pub/npc/20 ... ay2016.pdf

Tejas, and its May 17 flight, is the result of over 30 years of work and through those three decades, the plane’s engineers endured unending taunts and even threats of imprisonment. Dr V.S.Arunachalam, a former scientific adviser to the defence minister and chief of DRDO remembers the
day they almost lost the plane.
“At one meeting in 1991, chaired by then Defence Minister Sharad Pawar, MP Suresh Kalmadi, said we should be sent behind bars because he had found large-scale misappropriation of funds. But Ratan Tata, who was invited to the meeting along with other industrialists had a contrary opinion.
Tata told the minister that we had chosen the best technology and if for some reason the government wished to scrap the project, the Tata Group would take over and make the aircraft themselves. Pawar then decided to support us as many others had agreed with Tata,” he says.

[Aditya_V]

From Anatha Krishnan on Twitter

https://twitter.com/writetake/status/11 ... 1597745152

#Tejas FOC variants to have a-to-a refueling probe, Gsh-23 mm gun, pressure refueling with 3 drop tank config, integration of 725\450 L drop tank, improved wing nav lamp, in-flight windmill relight, tandem pylon\zoom climb.

while 725 Liter is a Subsonic drop tank, is the 450 Liter a subsonic or supersonic drop tank?

Has the IAF developed any PGM's or Bombs which can be delivered/ dropped or even carried at Supersonic speeds or these are all restricted to subsonic speeds so our strike missions are all restricted to subsonic speeds?

If there are no such BOMBS/ PGM's which can be carried or released at Supersonic speeds are supersonic drop tanks restricted to long range CAP or intercept missions. For the Mig 21 it was really needed due to its short legs but do other aircraft require supersonic drop tanks on Intercept missions unless we are going to intercept aircraft over enemy territory?

[srai]

^^^
Is this 450L tank new addition?

Then there is a 710L supersonic tanks as well.

[Aditya_V]

Yup this 450 Liter tank has come out of the blue, all previous reports talk of a centerline 710 L supersonic tank and 725 Liter subsonic centerline tank and 1200 Inner wing pylon and 800L midboard wing pylon tanks.

[Haridas]

Not sure if this was discussed here before or if this man's info is accurate but interesting bits include

Uttam has demonstrated detection of 1msq target at 105km but will be capable of up to 160km with more power.

Can track 100 targets simultaneously

Currently has about 750 trms.

https://youtu.be/Im2ajJtRSdE

There is also a little table that compares it to the rbe2 and klj series towards the end.

Significantly higher voltage GaN transistors are now becoming available that IMHO would increase TRM power output by 2 to 3 times. Thus the Uttam range will only continue to go up from where it is now.

With Uttam on LCA, there is pressing need for matching longer range AAM.

I see that Integra Tech has now 100-150V GaN RF transistors (@20watt/mm^2 ), that will give 3-4 times power of current GaN devices. So compared to GaS TRM modules the Uttam power could scale up on power by 10 times (about 3 time range increase). So IAF & DRDO should plan for properly matched armory.

Not to mention that out potential challengers will get in hand similarly improved system against India.

[kit]

Jay mentioned going supersonic as quickly as possible after takeoff before starting the climb. But then the aircraft will bleed airspeed during the climb and not be flying supersonic by the time it reaches the desired altitude. Not sure how it helps. It would be much easier to accelerate to supersonic speed after climbing in the thinner air at a higher altitude than the dense air closer the the ground just after takeoff.

Correct. In zoom climb you trade off KE for PE to achieve higher climb rate than what can be achieved in sustained powered climb. Jet engines find it much easier to give max possible thrust at given altitude at lower altitudes than at higher altitudes. Hence one can extract max energy out of the engines at low altitude at higher rate and then trade it off for height in climb.

IR,

Vertical turn in supersonic flight should not be too difficult. it need not be 8-9G, but fighters are rated for 5-6G typically at supersonic speeds. Besides the plane will quickly lose speed to go subsonic again, but in those precious few seconds it would have climbed a few '000 ft easily. Also it will be useful for lightly loaded configurations only. Interception is the ideal one I feel.

Gripen has something called Tiger Start, which allows it to TO from -40C completely cold start within 90sec. I wonder if LCA has something like this too. Though we don't have a very pressing need to have such mode.

Done. Way back in 2015.

https://www.livefistdefence.com/2015/01 ... -star.html

[kit]

Significantly higher voltage GaN transistors are now becoming available that IMHO would increase TRM power output by 2 to 3 times. Thus the Uttam range will only continue to go up from where it is now.

With Uttam on LCA, there is pressing need for matching longer range AAM.

I see that Integra Tech has now 100-150V GaN RF transistors (@20watt/mm^2 ), that will give 3-4 times power of current GaN devices. So compared to GaS TRM modules the Uttam power could scale up on power by 10 times (about 3 time range increase). So IAF & DRDO should plan for properly matched armory.

Not to mention that out potential challengers will get in hand similarly improved system against India.

So with more space and size such as a Su 30 Uttam can potentially outrange every other radar out there ? ., granted the power generation and heat dissipation is taken care of ?

[Cain Marko]

Significantly higher voltage GaN transistors are now becoming available that IMHO would increase TRM power output by 2 to 3 times. Thus the Uttam range will only continue to go up from where it is now.

With Uttam on LCA, there is pressing need for matching longer range AAM.

I see that Integra Tech has now 100-150V GaN RF transistors (@20watt/mm^2 ), that will give 3-4 times power of current GaN devices. So compared to GaS TRM modules the Uttam power could scale up on power by 10 times (about 3 time range increase). So IAF & DRDO should plan for properly matched armory.

Not to mention that out potential challengers will get in hand similarly improved system against India.

So,can anyone say what are the possible constraints when using GaN powered TRMs? Cooling requirements?

[Prasad]

Yes. Higher power, materials needed to ensure efficient cooling of not just fighter radars but large arrays too. Liquid cooling has weight penalties.

[JayS]

Done. Way back in 2015.

https://www.livefistdefence.com/2015/01 ... -star.html

I am aware of this. But there is no information on how much time it takes from cold engine to TO, AFAIK. It may take 1min or 10min or something else.

[Haridas]

So,can anyone say what are the possible constraints when using GaN powered TRMs? Cooling requirements?

Yes. Higher power, materials needed to ensure efficient cooling of not just fighter radars but large arrays too. Liquid cooling has weight penalties.

For India just to get these top rated parts.
Yes matching heat alliviation techniques is evolving. Encouraged by forced liquid jet cooling (patented).
But TRM has lower duty cucles.

US ground radars already deployed with GaN TRM

[Dileep]

Heat removal is the number one problem in AESA. It was some jubilation when Uttam could finally fit everything into the Tejas budget.

LRDE is preparing to make LSP builds now, as per chaiwale.