Tejas Mk.1 & Mk.1A News & Discussions: 09 February 2018

shiv · Post by **shiv** » 16 Mar 2018 22:10

In general I am nowadays reading defence news articles like the Bollywood pages of a paper. I look at the wimmen's pics and read nothing. That said I did read a critical article about Tejas where its radius seems to have mysteriously changed from 250 km to 450 km which is still not enough. Apparently. But there no wimmen pics so i moved on...

Kartik · Post by **Kartik** » 16 Mar 2018 22:25

thammu wrote:Why do all newspaper keep reporting - Tejas has lower endurance than Gripen by a factor of 2-3. Both are similar aircraft with similar engines and similar weight?

Can an Expert explain to a non-expert like me? It's all the more intriguing as Tejas went non-stop to Bahrain air show.

Not all newspapers. But those with a clear agenda. Rajat Pandit has a clear agenda, we've all known about it for a long time now. Rahul Bedi, Vivek Raghuvanshi, all these people fall under that category- people writing articles with an agenda.

Kartik · Post by **Kartik** » 16 Mar 2018 22:32

thammu wrote:
Cain Marko wrote: Why? Because ..
A. They are ignorant and arrogant enough to not want to learn any better. Bad combination that... Ignorance plus arrogance.
B. They are paid... What is called lifafa journalism in the board.
Then please tell, endurance figures for Tejas vs. Gripen or if there is no such spec figure as 'endurance', then the range in km.

If you can do some maths yourself, you'd be able to tell.

Gripen C vs Tejas Mk1 fuel figures are almost the same, perhaps a difference of a few kgs. i.e. ~2400 kgs fuel on board max.

They both have F-404 engine variants, with similar Specific Fuel Consumption in kg/hour per unit of thrust.

But the Tejas Mk1 lacks OBOGS and carries LOX cylinders. Gripen C/D have OBOGS and that means no specific restriction in mission duration due to oxygen running out. That is the only difference. And the Gripen C/D have better aerodynamics, with better fineness ratios. But that would add a few minutes worth of endurance but not double it or double the range.

But, the Gripen C will also run out of fuel, approximately around the same time as a Tejas, and well before any oxygen limitation arises.

But Rajat Pandit does not have a thinking mind and logic does not bother him. Hence, such logic would not make a whit of a difference to him and he will continue to peddle BS in his articles.

Rakesh · Post by **Rakesh** » 16 Mar 2018 22:35

^^^ Do we know when OBOGS will be coming?

Dileep · Post by **Dileep** » 16 Mar 2018 22:42

About the T90 v/s Arjun comparison: Remember that Tejas is operated by ranking commissioned officers, while the Tank is operated by Enlisted men. Makes a lot of difference.

Let me repeat: HAL will keep on producing, and IAF will keep on inducting. MK2 will come when it comes, and get phased in into the stream.

JayS · Post by **JayS** » 16 Mar 2018 22:52

Dileep wrote:About the T90 v/s Arjun comparison: Remember that Tejas is operated by ranking commissioned officers, while the Tank is operated by Enlisted men. Makes a lot of difference.

Let me repeat: HAL will keep on producing, and IAF will keep on inducting. MK2 will come when it comes, and get phased in into the stream.

I say, Lets stick this post on BR home page, right on front..

Prem Kumar · Post by **Prem Kumar** » 16 Mar 2018 23:00

Kartik: excellent post. You should write a short & brutal rebuttal in Swarajya or OpIndia about the lies of people like Rajat Pandit. We now have these news outlets which will publish such views.

Its a shame if this knowledge remains confined to BRF

sohamn · Post by **sohamn** » 17 Mar 2018 00:05

Kartik wrote:
thammu wrote:
Then please tell, endurance figures for Tejas vs. Gripen or if there is no such spec figure as 'endurance', then the range in km.
If you can do some maths yourself, you'd be able to tell.

Gripen C vs Tejas Mk1 fuel figures are almost the same, perhaps a difference of a few kgs. i.e. ~2400 kgs fuel on board max.

They both have F-404 engine variants, with similar Specific Fuel Consumption in kg/hour per unit of thrust.

But the Tejas Mk1 lacks OBOGS and carries LOX cylinders. Gripen C/D have OBOGS and that means no specific restriction in mission duration due to oxygen running out. That is the only difference. And the Gripen C/D have better aerodynamics, with better fineness ratios. But that would add a few minutes worth of endurance but not double it or double the range.

But, the Gripen C will also run out of fuel, approximately around the same time as a Tejas, and well before any oxygen limitation arises.

But Rajat Pandit does not have a thinking mind and logic does not bother him. Hence, such logic would not make a whit of a difference to him and he will continue to peddle BS in his articles.

Gripen C/D has internal fuel load of 2,270 kg and an empty weight of 6,800 kg

Tejas has internal fuel of 2,458 kg and an empty weight of 6560 Kg

Since we know Gripen has a better AoA and less drag than Tejas so beyond marketing fluff at best Gripen C/D should have an extra endurance of 5-10 mix Max.

According to Gripen website, the combat range of Gripen with two drop tanks is 1500 km, or 750 km combat radius. But most sites state the combat radius of Tejas is 500km with two drop tanks. What I am not able to decipher is how come Gripen is doing 500 kms more with almost identical characteristics. Is the Aerodynamic performance so poor in Tejas that the range drops by a third?

ArjunPandit · Post by **ArjunPandit** » 17 Mar 2018 00:19

^^the double delta should generate more drag could that be the reason?

nam · Post by **nam** » 17 Mar 2018 00:29

These numbers mean nothing. What is the cursing height that would achieve 750KM for Gripen? What is the weight of the drop tanks carried by it? At what loadout is the number measured? You don't expect Gripen to reach 750KM, with no missiles or bombs?

Gripen may have better range because due to efficient wing design, however will it not be effected by Gripen extra weight? Dragging 250KG extra weight compared to LCA using the same engine will have no effect?

The brochure numbers mean nothing.

Kartik · Post by **Kartik** » 17 Mar 2018 00:33

Well, I would suggest you to read the Swiss evaluation reports. They evaluated the Rafale, Typhoon and the Gripen C. And the Gripen C was a distant third in almost all criteria, including range and endurance.

I've linked the leaked report here. READ IT IN FULL!!

And this is just the summary

Endurance and Aircraft Performance was one of the Gripen C's LIMITING FACTORS as per the Swiss Air Force's evaluation team. It didn't even meet the vanilla F/A-18 Hornet's benchmark in Air Policing, so what does one say of more challenging missions? It was also found inferior to the vanilla F/A-18 Hornet in Defensive Counter Air (DCA) missions and other missions as well.

The media PR that Saab does is masterful. The facts don't seem to match up to that.

ramana · Post by **ramana** » 17 Mar 2018 00:44

Kartik, Since you seem to be closest to this thing, can you write and will get it into Swarajya.

Add a few tables to show what weights we are talking about a couple of awesome Tejas pictures to ensure Hakim read the article!!!

Lots of BRF on twitter and will get it read!.

Vivek K · Post by **Vivek K** » 17 Mar 2018 01:33

We need to push TOI to correct the facts published by Rajat Pandit. BRF should set up a team of 2-3 to rebut and post an article to TOI editors and ask them to retract incorrect figures deliberately published by lifafa journallists.

Kartik · Post by **Kartik** » 17 Mar 2018 02:11

ramana wrote:Kartik, Since you seem to be closest to this thing, can you write and will get it into Swarajya.

Add a few tables to show what weights we are talking about a couple of awesome Tejas pictures to ensure Hakim read the article!!!

Lots of BRF on twitter and will get it read!.

Will do Ramana. I've been putting off writing on this for a long time.

SaiK · Post by **SaiK** » 17 Mar 2018 06:59

Presstitutes on target course...

Hindustantimes
Air Force struggles to create Tejas fleet as HAL misses delivery targets

https://m.hindustantimes.com/india-news ... P_amp.html

srin · Post by **srin** » 17 Mar 2018 07:28

sohamn wrote:
Gripen C/D has internal fuel load of 2,270 kg and an empty weight of 6,800 kg

Tejas has internal fuel of 2,458 kg and an empty weight of 6560 Kg

Wow, I cross-checked and found you are right. And GE-404IN20 has 5% better thrust than the 404-derived RM-12 that powers the Gripen.

I learned two new things today on this forum that I hadn't known about Gripen and both are surprising.
- Tejas Mk1 is lighter than Gripen C/D and has more powerful engines. Yet, Tejas is underpowered / 3-legged cheetah.
- If Gripen E actually first flew in 2016, what did we test for MMRCA trials ?
- If Gripen E was evaluated for MMRCA, does that mean Tejas Mk2 is now MMRCA contender ?

JayS · Post by **JayS** » 17 Mar 2018 10:07

srin wrote:
sohamn wrote:
Gripen C/D has internal fuel load of 2,270 kg and an empty weight of 6,800 kg

Tejas has internal fuel of 2,458 kg and an empty weight of 6560 Kg
Wow, I cross-checked and found you are right. And GE-404IN20 has 5% better thrust than the 404-derived RM-12 that powers the Gripen.

I learned two new things today on this forum that I hadn't known about Gripen and both are surprising.
- Tejas Mk1 is lighter than Gripen C/D and has more powerful engines. Yet, Tejas is underpowered / 3-legged cheetah.
- If Gripen E actually first flew in 2016, what did we test for MMRCA trials ?
- If Gripen E was evaluated for MMRCA, does that mean Tejas Mk2 is now MMRCA contender ?

Gripen E first flew on 15 June 2017. Its running late already and a full ton overweight. Most Gripen E brochure figures are based on empty weight of 7 ton. Its 8ton now.

Most of MMRCA contenders were far from final config promised. But thats not a problem for imported maal. Just promises are taken as credible things. Anyways.

Kartik wrote:
thammu wrote:
Then please tell, endurance figures for Tejas vs. Gripen or if there is no such spec figure as 'endurance', then the range in km.
If you can do some maths yourself, you'd be able to tell.

Gripen C vs Tejas Mk1 fuel figures are almost the same, perhaps a difference of a few kgs. i.e. ~2400 kgs fuel on board max.

They both have F-404 engine variants, with similar Specific Fuel Consumption in kg/hour per unit of thrust.

But the Tejas Mk1 lacks OBOGS and carries LOX cylinders. Gripen C/D have OBOGS and that means no specific restriction in mission duration due to oxygen running out. That is the only difference. And the Gripen C/D have better aerodynamics, with better fineness ratios. But that would add a few minutes worth of endurance but not double it or double the range.

But, the Gripen C will also run out of fuel, approximately around the same time as a Tejas, and well before any oxygen limitation arises.

But Rajat Pandit does not have a thinking mind and logic does not bother him. Hence, such logic would not make a whit of a difference to him and he will continue to peddle BS in his articles.

Let me ask a question, how do we know Gripen has better aerodynamics than Tejas..? Do we have any data to prove that..? Any credible information/statement from a trustworthy person who must have had access to actual classified data...? On what basis we should assume Gripen had better aerodynamics than LCA..? Just saying..

Avarachan · Post by **Avarachan** » 17 Mar 2018 10:37

Kartik wrote:
ramana wrote:Kartik, Since you seem to be closest to this thing, can you write and will get it into Swarajya.

Add a few tables to show what weights we are talking about a couple of awesome Tejas pictures to ensure Hakim read the article!!!

Lots of BRF on twitter and will get it read!.
Will do Ramana. I've been putting off writing on this for a long time.

I'm planning to write an article to coincide with the FOC of the Tejas (hopefully, December 2018). Perhaps BRF can publish a symposium with perspectives from some of the senior members. I don't have the technical background that the gurus have, but I am familiar with the geopolitical issues involved. For instance, most people don't understand what was really happening with the MMRCA contest and how it was related to the Tejas's development.

I don't care for Swarajya's perspective and won't publish my work there. But I'm open to working with BRF. If BRF doesn't want to take this up, I'll probably publish my article with Saker. I can be reached at my username dot nine seven at Larry and Sergei's service. I'll start working on the article in several months.

Avarachan · Post by **Avarachan** » 17 Mar 2018 10:45

JayS wrote:Let me ask a question, how do we know Gripen has better aerodynamics than Tejas..? Do we have any data to prove that..? Any credible information/statement from a trustworthy person who must have had access to actual classified data...? On what basis we should assume Gripen had better aerodynamics than LCA..? Just saying..

JayS, I'm eagerly waiting for someone to publish a detailed article on the aerodynamics of the Tejas.

In 2014, NASA published a great e-book, "Elegance in Flight," on the development of the F-16 XL.
https://www.nasa.gov/sites/default/file ... flight.pdf
I would love to see something like that on the development of the Tejas. Indian youth need to know about the great work being done.

ramana · Post by **ramana** » 17 Mar 2018 11:51

JayS, Can we estimate from the geometry?
Suppose we do view foil CAD.
Have print of Grippen on an overlay sheet and Tejas on another.
Off course need to be same scale!
Then overlaw them.
I thought Tejas was draggy due to not having sufficient length in the wing region for supersonic region.

thammu · Post by **thammu** » 17 Mar 2018 14:01

Kartik wrote:
thammu wrote:
Then please tell, endurance figures for Tejas vs. Gripen or if there is no such spec figure as 'endurance', then the range in km.
If you can do some maths yourself, you'd be able to tell.

Gripen C vs Tejas Mk1 fuel figures are almost the same, perhaps a difference of a few kgs. i.e. ~2400 kgs fuel on board max.

They both have F-404 engine variants, with similar Specific Fuel Consumption in kg/hour per unit of thrust.

But the Tejas Mk1 lacks OBOGS and carries LOX cylinders. Gripen C/D have OBOGS and that means no specific restriction in mission duration due to oxygen running out. That is the only difference. And the Gripen C/D have better aerodynamics, with better fineness ratios. But that would add a few minutes worth of endurance but not double it or double the range.

But, the Gripen C will also run out of fuel, approximately around the same time as a Tejas, and well before any oxygen limitation arises.

But Rajat Pandit does not have a thinking mind and logic does not bother him. Hence, such logic would not make a whit of a difference to him and he will continue to peddle BS in his articles.

Thanks, this was the answer I was looking for. Will use it, whenever I meet anybody with decision making power on this subject.

jaysimha · Post by **jaysimha** » 17 Mar 2018 14:27

^^
But this drdo note says

Indigenous On-board Oxygen Generating System based Integrated Life Support System for Tejas

https://www.drdo.gov.in/drdo/pub/newsle ... feb_15.pdf

May be they have not integrated yet with Tejas.

maitya · Post by **maitya** » 17 Mar 2018 14:47

ArjunPandit wrote:^^the double delta should generate more drag could that be the reason?

Ummm, would you really need Thrust and only Thrust to negate drag is it? How about lift? And how about vortex-induced lift and more so about flow-attachment aspects of LCAs double-delta config etc.

Some references are here and here.
(the embedded pics and charts are of-course non-existent now ...)

Neshant · Post by **Neshant** » 17 Mar 2018 19:14

JayS wrote:
Let me ask a question, how do we know Gripen has better aerodynamics than Tejas..? Do we have any data to prove that..? Any credible information/statement from a trustworthy person who must have had access to actual classified data...? On what basis we should assume Gripen had better aerodynamics than LCA..? Just saying..

Supposedly foreplanes were removed from Su-35 because it created too much drag.

Since Gripen has foreplanes and Tejas does not, the former could well be less not more aerodynamic under many operational circumstances.

The marketing brocheurs always lie but it could be that naive babuz take them at face value.

SaiK · Post by **SaiK** » 18 Mar 2018 04:14

Didn't we read in the previous pages one of our stalwart gurus declare Mk2 to have the canards?

80* A

A

ps:
The final contract for the procurement of 83 LCA is expected to be signed soon /newj

Rakesh · Post by **Rakesh** » 18 Mar 2018 19:42

https://twitter.com/strategic_front/sta ... 1282145280 ---> Indian Air Force 45 Squadron flying Tejas closing in on 1,000 sorties since July 2016. Huge amount of hours accumulated in such a short time with such a limited number of jets. Speaks very highly of the LCA's serviceability and availability rates.

thammu · Post by **thammu** » 18 Mar 2018 20:04

Rakesh wrote:https://twitter.com/strategic_front/sta ... 1282145280 ---> Indian Air Force 45 Squadron flying Tejas closing in on 1,000 sorties since July 2016. Huge amount of hours accumulated in such a short time with such a limited number of jets. Speaks very highly of the LCA's serviceability and availability rates.

+1

ArjunPandit · Post by **ArjunPandit** » 18 Mar 2018 20:39

where are the journos who said it can't fly without telemetry

Khalsa · Post by **Khalsa** » 19 Mar 2018 02:39

Dileep wrote:About the T90 v/s Arjun comparison: Remember that Tejas is operated by ranking commissioned officers, while the Tank is operated by Enlisted men. Makes a lot of difference.

Let me repeat: HAL will keep on producing, and IAF will keep on inducting. MK2 will come when it comes, and get phased in into the stream.

I really admire your chutzpah and I do back up the others when they say that this post should be put front and centre of BR.
I go a step more and say put it in front of the Tin Can Importers.

But I do have a couple of queries.

1. The Arjun is operated by more than just enlisted man. The tank commander is usually a commissioned officer and said that I have found the attitude of the enlisted man to be more sympathetic and/or open to equipment. The Indian jawan has more confidence in himself than it surfaces across. Would you agree or disagree ?

2. Now on the Tejas, the equipment is also operated and diligently worked upon by a lot of techs who may not have a space and a role on board the aircraft but it does not mean they are any less detached. Would you agree or disagree ?

I think the key part of your slam dunk statement is
HAL Keep on producing
IAF Keep on Inducting

There is no dearth of equipment in the IA. We can churn out t-72 and t-90s as and when we want.
Its the seriousness of falling squadron matters that is pushing IAF to adopt the tejas.

By the way on the matter of men of armoured regiments speaking about Arjun
Please do check this out if you havent already so
https://www.ndtv.com/video/news/the-buc ... ion-476190

suryag · Post by **suryag** » 19 Mar 2018 10:33

Tejas FB admin has confirmed that the full BVR integration is done. IR sir all those interfacing and vibration issues are cleaned up or is this some other BVR that has been integrated.

Singha · Post by **Singha** » 19 Mar 2018 10:57

only astra and derby were on plan. derby + EL2032 + its pylon interface box would have come prequalified COTS.
would love to see Astra being qualified and used in huge nos across our sukhoi and tejas fleet.

Indranil · Post by **Indranil** » 19 Mar 2018 12:08

suryag wrote:Tejas FB admin has confirmed that the full BVR integration is done. IR sir all those interfacing and vibration issues are cleaned up or is this some other BVR that has been integrated.

There was never any problem with any missiles other than the Python 5. All those fins in the front did not jive well with the wing. Python5 in its current form will not be integrated with Tejas. There is a lot of brouhaha about ASRAAM. I have not heard of it. Astra is planned to be integrated.

Dileep · Post by **Dileep** » 19 Mar 2018 13:06

Khalsa wrote:
Dileep wrote:About the T90 v/s Arjun comparison: Remember that Tejas is operated by ranking commissioned officers, while the Tank is operated by Enlisted men. Makes a lot of difference.

Let me repeat: HAL will keep on producing, and IAF will keep on inducting. MK2 will come when it comes, and get phased in into the stream.
But I do have a couple of queries.

1. The Arjun is operated by more than just enlisted man. The tank commander is usually a commissioned officer and said that I have found the attitude of the enlisted man to be more sympathetic and/or open to equipment. The Indian jawan has more confidence in himself than it surfaces across. Would you agree or disagree ?

2. Now on the Tejas, the equipment is also operated and diligently worked upon by a lot of techs who may not have a space and a role on board the aircraft but it does not mean they are any less detached. Would you agree or disagree ?

The point is, Air Force officers gets a lot of say (and ears) about their equipment than their Army counterparts. There are many reasons:

1. Small numbers of users. All officers.
2. "putting his life on line" carries a lot of weight. Do we say a Tank commander "putting his life on line" (for non-combat work)
3. Higher visibility.
etc.. etc.

Dileep · Post by **Dileep** » 19 Mar 2018 13:10

Indranil wrote:
suryag wrote:Tejas FB admin has confirmed that the full BVR integration is done. IR sir all those interfacing and vibration issues are cleaned up or is this some other BVR that has been integrated.
There was never any problem with any missiles other than the Python 5. All those fins in the front did not jive well with the wing. Python5 in its current form will not be integrated with Tejas. There is a lot of brouhaha about ASRAAM. I have not heard of it. Astra is planned to be integrated.

That is not what I heard about Py5.

putnanja · Post by **putnanja** » 19 Mar 2018 13:30

Dileep wrote:
Indranil wrote: There was never any problem with any missiles other than the Python 5. All those fins in the front did not jive well with the wing. Python5 in its current form will not be integrated with Tejas. There is a lot of brouhaha about ASRAAM. I have not heard of it. Astra is planned to be integrated.
That is not what I heard about Py5.

Dileep, you can't leave us hanging like that

Please let us know what you heard

Dileep · Post by **Dileep** » 19 Mar 2018 17:59

What I heard was the other way on both points, ie "not influence of fins" and "Py5 issue being fixed"

JayS · Post by **JayS** » 19 Mar 2018 19:25

Avarachan wrote:
JayS wrote:Let me ask a question, how do we know Gripen has better aerodynamics than Tejas..? Do we have any data to prove that..? Any credible information/statement from a trustworthy person who must have had access to actual classified data...? On what basis we should assume Gripen had better aerodynamics than LCA..? Just saying..
JayS, I'm eagerly waiting for someone to publish a detailed article on the aerodynamics of the Tejas.

In 2014, NASA published a great e-book, "Elegance in Flight," on the development of the F-16 XL.
https://www.nasa.gov/sites/default/file ... flight.pdf
I would love to see something like that on the development of the Tejas. Indian youth need to know about the great work being done.

I have expressed same wish 2-3 times here. I wanted to see someone like KH write a book on LCA. It could be as you said, an inspiration for younger generation. I would even commission a book if I were the RM. Hire a pro writer to pen the saga.

JayS · Post by **JayS** » 19 Mar 2018 20:00

ramana wrote:JayS, Can we estimate from the geometry?
Suppose we do view foil CAD.
Have print of Grippen on an overlay sheet and Tejas on another.
Off course need to be same scale!
Then overlaw them.
I thought Tejas was draggy due to not having sufficient length in the wing region for supersonic region.

We can do something worthwhile with simplified analysis like Vivek Ahuja did. But we need some data to calibrate. I have been looking for Gripen data but no luck so far. For Tejas we have some small amount of data at least. Without calibration any comparison is only so much reliable. But we have to remember than even hi-fi CFD doesn't agree fully with flight data.

Tejas has higher transonic drag due to suboptimal area ruling. But is it worse than Gripen..?? Is Tejas worse than Gripen in all regimes of flight envelop..? I don't know. There are n number of things in Aerospace which are counter-intuitive because the configuration was dictated by unusual parameters. I am yet to see any credible head-to-head comparison of Tejas and Gripen.

shiv · Post by **shiv** » 19 Mar 2018 20:43

As we head into the unknown I believe it is necessary to look at the reason for these "scientific backward somersaults" we are doing here. And we are doing these backward somersaults because some people in the media - and that includes manufacturers and supporters of the Gripen have told us that Gripen has a range of X and Tejas has a range of Y and X>Y and we believe them. Why we believe them and set out to try and do some "skyentifik kalkoolasons" to prove or disprove some obviously fragmentary and likely biased information I have no clue.

But lets not stop. Lets carry on and pretend that something is going to come out of this.

ArjunPandit · Post by **ArjunPandit** » 19 Mar 2018 21:46

^^thats quintessential part of being "argumentative indian". Do it because thats what rational people are supposed to do, unlike the chi-pakis who believe their JF 17 is superior to F16 and J20 to F22/F35.
Not to forget it reminds people (including me) that designing a fighter jet is far more complicated than anything we've ever seen in our personal / professional lives