Tejas Mk2 Medium Weight Fighter: News & Discussion - 23 February 2019

basant · Post by **basant** » 11 Apr 2020 23:34

Thank Gyan for the very informative post!

I have a little doubt. The advantage of FBW based longer range for the delta-winged LCA is true. However, as a design choice was it a factor? The design decision was made in early 90s (1990-91) whereas the study of F-16XL, if I am not wrong, was published in 2004 while the studies were done in 1990s. Was this relation between FBW to range was known during design phase before the selection was made?

Gyan · Post by **Gyan** » 11 Apr 2020 23:49

Yes, two reasons:-

Mirage 2000

Second ADA can do their own research, I am referring to NASA study to support my argument. ADA was not waiting for public release of NASA study. Also BAE & Dassault Consultants to ADA had deep knowledge of Delta wing

basant · Post by **basant** » 12 Apr 2020 02:04

Gyan wrote:Yes, two reasons:-

Mirage 2000

Second ADA can do their own research, I am referring to NASA study to support my argument. ADA was not waiting for public release of NASA study. Also BAE & Dassault Consultants to ADA had deep knowledge of Delta wing

Thanks for the clarification!

JayS · Post by **JayS** » 12 Apr 2020 11:45

basant wrote:Thank Gyan for the very informative post!

I have a little doubt. The advantage of FBW based longer range for the delta-winged LCA is true. However, as a design choice was it a factor? The design decision was made in early 90s (1990-91) whereas the study of F-16XL, if I am not wrong, was published in 2004 while the studies were done in 1990s. Was this relation between FBW to range was known during design phase before the selection was made?

FBW benefits are generic, not tied to the wing shape per se. FBW allows for statically unstable design reducing trim drag and possibly also improving L/D significantly with certain configurations. The principle and practical applications predates LCA by decades.

khan · Post by **khan** » 12 Apr 2020 11:54

Will FBW reduce drag on conventional swept wing planes? If yes, how much - marginally or substantially?

JayS · Post by **JayS** » 12 Apr 2020 12:30

khan wrote:Will FBW reduce drag on conventional swept wing planes? If yes, how much - marginally or substantially?

Difficult to say how much without specific configuration. For fighter it may and for civilian jets i may not. Also depends on Tail vs canard vs tailless config. But in general for fighters, FBW allows you to have relaxed static stability which allows you to trim, for same condition, at lower AoA and effectively lower total drag.

Just googled quickly. A good presentation of this phenomenon is on slide 12 of this F-16 related doc. See with relaxed static stability, how the Horizontal tail needs to produce less negative lift for trimming at both subsonic and supersonic cases. This means less reduction in total life, so wing can be trimmed at lower AoA for same lift requirement. Also less deflection of tail and less AoA of wing means lower overall drag.

http://www.dept.aoe.vt.edu/~mason/Mason_f/F16S04.pdf

nam · Post by **nam** » 12 Apr 2020 13:35

One of the advantage of M2K delta wing over F16 wings is the ability to fly higher. This is very important in BVR. Needless to say LCA was designed for future BVR fights, so it makes sense to go for M2K style delta.

LCA is IAF's desire to have more M2K.

Then the question needs to ask is why didn't we just create a M2K sized delta figher with M2K engine? We wouldn't have faced with this "size" issue.

Well IAF wanted Mig21 replacement in Mig21 sized fighter, to prevent replacing shelters.

Afterwards IAF wanted more M2K to replace Mig21 before the infamous MMRCA 1.0. By that time, it was too late.

JayS · Post by **JayS** » 12 Apr 2020 14:36

I think the low wing-loading for LCA is result of two factors - high ITR and good hot and high performance specified. For the small size, there are little options left other than delta wing to achieve the required W/S.

Gyan · Post by **Gyan** » 12 Apr 2020 14:51

nam wrote:
Then the question needs to ask is why didn't we just create a M2K sized delta figher with M2K engine? We wouldn't have faced with this "size" issue.

Well IAF wanted Mig21 replacement in Mig21 sized fighter, to prevent replacing shelters.

Afterwards IAF wanted more M2K to replace Mig21 before the infamous MMRCA 1.0. By that time, it was too late.

After 4000 word post, addressing only this issue, This is your question?

Yagnasri · Post by **Yagnasri** » 12 Apr 2020 15:15

Great post Guanji.

Avtar Singh · Post by **Avtar Singh** » 12 Apr 2020 18:52

someone from my past

AUGURS WELL FOR TEJAS PLATFORM/LINE OF AIRCRAFT

Interview with Ian Black on the Lightning

https://www.youtube.com/watch?v=nerDSROnAc4

at 49.00 ===>>> Mirage 2000
starts exchange tour with French Air Force, only given manuals in French!!!

much more lax attitude compared to RAF
first day; solo in single seater/air combat in a single seater/solo in a dual seater/
solo night…
flying around the alps at 250 feet
How long would that take in RAF? probably about six years!!

Mirage 2000 is probably the ultimate fighter pilots aeroplane...
said not having flown typhoon/rafale/f22

mix between lightning and mirage with fly by wire... pull 9.5g all day long

similar to f16 it could turn 400kts 9.5g but left with only 200kts and out of ideas
DUE TO DELTA WING. could wax other aircraft very easily

FAF... always flew everyday some times twice a day

he did ACM (in mirage) with tornados F3s and harriers... unfair to comment because he does not want to embarass the RAF

FAF more gung ho compared to RAF... air to air gunnery at 400kts 9g
RAF only allowed air to air gunnery 200kts 2g

650 hours on the ultimate boys toy in south of france

nachiket · Post by **nachiket** » 14 Apr 2020 01:07

Gyan wrote:Intention of Indian DRDO & IAF Brass :-

We always intended to develop an aircraft way more advanced than F-16/Mirage 2000 with “more range” We went about portraying it as little toy aircraft to avoid attracting attention during Cold War Era and subsequently to avoid getting the programmed derailed by competitors. Remember our polite non-threatening Dr. Abdul Kalam working on sounding rockets. The Aim to develop long range Ballistic Missiles was always his real intent.

My understanding is that LCA was intended to be 1000-1200km range aircraft, and even now its 800-900km range aircraft (due to weight gain)
In any case, the discussion is all the more pertinent because for LCA Mk-2 we are retaining the same Wingform with Canards.

To understand the design issues facing ADA (which was to develop a aircraft equivalent to F-16/Mirage 2000 while using GE F404 – 75kn engine),

nam wrote: LCA is IAF's desire to have more M2K.

Then the question needs to ask is why didn't we just create a M2K sized delta figher with M2K engine? We wouldn't have faced with this "size" issue.

Where are you guys getting this from? LCA was never intended to have Mirage-2000 levels of performance and it did not come out of some desire to "have more m2k". Show me any old news article or document which states that ADA set about creating a desi Mirage-2000 rather than a Mig-21 replacement.

When you start off with a completely incorrect assumption, the rest of your analysis will end up incorrect as well.

I'll make it simple, you cannot get M2k levels of performance (payload/range) with an LCA Mk-1 sized aircraft. It is not possible. Dassault would have had to do a very shitty job of designing the M2k if the same performance could be obtained from an aircraft much smaller and lighter and with a smaller engine. And we know Dassault did not do that. The M2k is a work of art as far as its design is concerned. And so is the F-16.

This is an incredible attempt at moving goalposts. First claim without proof that the LCA mk1 was supposed to have M2k/F-16 levels of performance and then conclude that it failed in its objectives based on the incorrect claim.

Even Mig-29 until recently has been very short ranged & maintenance heavy aircraft. Only when RD33/93 became powerful enough in this decade, its able to carry enough fuel using TWO Engines.

Where do you get your info from seriously? The RD-33 series 3 on our upgraded Mig-29's does not produce more thrust. The problem it fixes is the smokiness of the original RD-33. The Mig-29 never had problems with lack of thrust. It has a greater T:W ratio than most other fighters of its era. The original Mig-29 did not carry more fuel because it was not designed to. The Russians were designing the long range Su-27 in parallel. The Mig-29 was supposed to be a cheap, short range air defence fighter to be procured in large numbers. They were not waiting for more powerful engines to add more fuel to it.

nachiket · Post by **nachiket** » 14 Apr 2020 01:16

nam wrote:One of the advantage of M2K delta wing over F16 wings is the ability to fly higher.

Delta wings by themselves don't let the aircraft fly higher. The Mig-25 could fly higher than any delta winged aircraft around. The height ceilings are more dependent on engine and intake design. Perhaps you meant climb rate instead? Even that is not a simple comparison though.

Manish_Sharma · Post by **Manish_Sharma** » 14 Apr 2020 02:50

^I thought Non-Delta like f16 and Jaguars are created to perform optimally at lower level flights to evade ground radars, while all Deltas perform best at high ceilings.

Kartik · Post by **Kartik** » 14 Apr 2020 03:00

No that's not true. F-15s and F-16s that are not delta wing fighters have significantly lower wing loading than the Jaguar that was designed to be a stable bomb carrying platform at low levels. It is the wing loading that matters more in relation to stable flight at low levels.

On the F-16 (as on the Mirage and other delta wing fighters with low wing loading) FBW compensates for it by alleviating wind gusts that could pitch the aircraft up or down suddenly and create a rough ride for pilots.

Indranil · Post by **Indranil** » 14 Apr 2020 22:49

Gyan, I am happy to see that you are making a serious effort to learn. But some of the inferences that you are drawing are incorrect. It is part of learning.

JayS · Post by **JayS** » 14 Apr 2020 23:07

Free advice - don't get lost in the external looks of an Aircraft, if you are trying to understand how its designed. Shape comes later. First come Parameters like TWR and Wing loading. There are multiple ways of achieving same TWR and W/S combo (arrived at based on all SQR), and there is no one true superior way that the other. Plus dont get too bogged downed by certain characteristics you see, which may seem peculiar but often do not have as glorious technical rationale behind it as one may expect. Stick to the basics if you want to understand the fundamentals. Best read some Aircraft design book. Aircraft design books are typically fun to read and are not all that difficult to understand.

deejay · Post by **deejay** » 15 Apr 2020 00:01

@nachiket @indranil @JayS @Kartik - My many pranaams to you for your patience. My fuse shorted when the first post on Delta vs Swept Wing. I was half expecting someone to ask about why do we not have an elliptical wing design on Tejas.

Please do discuss dihedral vs Anhedral wing design next but folks in the right thread. I am being cheeky Sorry.

Rahul M · Post by **Rahul M** » 15 Apr 2020 00:45

Second JayS on the aircraft design book thingy. With my simple fyzziks background I found I could understand them to a decent level and thoroughly enjoyed it.

Kartik · Post by **Kartik** » 22 Apr 2020 05:20

From Vayu's March-April 2020 issue

-Preliminary design is almost done.
-Detailed design to begin from March 2020 (with Covid-19 most likely adding some schedule delay)
-Raw Material and LRU procurement has been started
-Development activities towards new LRUs started

The Tejas Mk.II for the Air Force was initially planned to have a higher thrust engine. However, in its new configuration it is no more a light combat aircraft but will be a Medium Weight Fighter (MWF).

This evolution of the MWF began with the IAF projecting a platform to replace the Mirage 2000, Jaguar and MiG-29 in the 2030s. The IAF wanted a multi-role fighter with improved range, endurance, lethality and increased payload carrying capacity. Based on these requirements, configuration optimisation studies were initiated by ADA in November 2016, a configuration with improved performance and increased internal fuel has thus evolved. Subsequently, the IAF also indicated their requirement for integrating heavier standoff weapons.The final configuration was agreed to in September 2018 to meet these capabilities.

Preliminary design of the MWF is at the final stages of completion and detail design activities are to begin from March 2020.

The procurement of raw material and LRUs has been initiated and development activities towards new LRUs initiated. The engineering cockpit simulator of the MWF was on display at Defexpo 2020, with a Large Area Display (LAD), sleek Head Up Display (HUD) and side control stick.

neerajb · Post by **neerajb** » 22 Apr 2020 13:40

JayS wrote: Difficult to say how much without specific configuration. For fighter it may and for civilian jets i may not. Also depends on Tail vs canard vs tailless config. But in general for fighters, FBW allows you to have relaxed static stability which allows you to trim, for same condition, at lower AoA and effectively lower total drag.

Just googled quickly. A good presentation of this phenomenon is on slide 12 of this F-16 related doc. See with relaxed static stability, how the Horizontal tail needs to produce less negative lift for trimming at both subsonic and supersonic cases. This means less reduction in total life, so wing can be trimmed at lower AoA for same lift requirement. Also less deflection of tail and less AoA of wing means lower overall drag.

http://www.dept.aoe.vt.edu/~mason/Mason_f/F16S04.pdf

Saw a documentary on F-16, narrator mentioned that F-16s horizontal tail provides +ve lift unlike conventional aircraft and hence the wing size can be reduced, tail size is reduced as well as compared to conventional aircraft because of less dependency on tail for pitch up. So the structural weight goes down for the same performance using relaxed static stability in addition to all the drag benefits that you mentioned. All these benefits were known to humans but I believe lack of computers earlier to control the aircraft was the reason behind conventional layouts.

MeshaVishwas · Post by **MeshaVishwas** » 24 Apr 2020 17:31

Finally, after years of tests the #OBOX for #Tejas have completed all ground-based trials at test rigs. It should fly on board one of the test variants, mostly PV3, for a series of of trials. #LCAMkII will be fitted with DEBEL #OBOX thereby adding another desi system.

https://twitter.com/writetake/status/12 ... 02753?s=19

OBOGS tests done!

RKumar · Post by **RKumar** » 24 Apr 2020 23:27

MeshaVishwas wrote:
Finally, after years of tests the #OBOX for #Tejas have completed all ground-based trials at test rigs. It should fly on board one of the test variants, mostly PV3, for a series of of trials. #LCAMkII will be fitted with DEBEL #OBOX thereby adding another desi system.
https://twitter.com/writetake/status/12 ... 02753?s=19

OBOGS tests done!

Jolly good news!! Keep it up guys

Atmavik · Post by **Atmavik** » 24 Apr 2020 23:41

this might have been mentioned here before. but its worth noting that this project enabled DRDO to make ventilators real fast.

Vivek K · Post by **Vivek K** » 25 Apr 2020 00:30

deejay wrote:@nachiket @indranil @JayS @Kartik - My many pranaams to you for your patience. My fuse shorted when the first post on Delta vs Swept Wing. I was half expecting someone to ask about why do we not have an elliptical wing design on Tejas.

Please do discuss dihedral vs Anhedral wing design next but folks in the right thread. I am being cheeky Sorry.

The more we educate, the fewer morons will question domestic systems.

JayS · Post by **JayS** » 25 Apr 2020 20:37

neerajb wrote:
JayS wrote: Difficult to say how much without specific configuration. For fighter it may and for civilian jets i may not. Also depends on Tail vs canard vs tailless config. But in general for fighters, FBW allows you to have relaxed static stability which allows you to trim, for same condition, at lower AoA and effectively lower total drag.

Just googled quickly. A good presentation of this phenomenon is on slide 12 of this F-16 related doc. See with relaxed static stability, how the Horizontal tail needs to produce less negative lift for trimming at both subsonic and supersonic cases. This means less reduction in total life, so wing can be trimmed at lower AoA for same lift requirement. Also less deflection of tail and less AoA of wing means lower overall drag.

http://www.dept.aoe.vt.edu/~mason/Mason_f/F16S04.pdf
Saw a documentary on F-16, narrator mentioned that F-16s horizontal tail provides +ve lift unlike conventional aircraft and hence the wing size can be reduced, tail size is reduced as well as compared to conventional aircraft because of less dependency on tail for pitch up. So the structural weight goes down for the same performance using relaxed static stability in addition to all the drag benefits that you mentioned. All these benefits were known to humans but I believe lack of computers earlier to control the aircraft was the reason behind conventional layouts.

Bingo..!

Rakesh · Post by **Rakesh** » 26 May 2020 18:55

https://twitter.com/hvtiaf/status/12635 ... 28513?s=20 ---> Nice article @Chopsyturvey. Though, can't agree on way forward. "We need help" conclusion is not adequately supported by technical arguments. 'Help' is a 3rd world concept. Can't agree on that word at all. We crossed that stage years ago.

https://twitter.com/Skbanbotra/status/1 ... 08738?s=20 ---> It has been written that, "The realistic first flight time-line would be 2028 and induction will be at 2035 timeline." Will it push retirement of Jaguars and Mirage 2000 ahead if we consider that line?

https://twitter.com/hvtiaf/status/12636 ... 37312?s=20 ---> Which aircraft?

https://twitter.com/Vamsina90252211/sta ... 03171?s=20 ---> I think he meant Tejas Mk2 sir.

https://twitter.com/hvtiaf/status/12636 ... 16097?s=20 ---> It's not anticipated to take long. A perception that Mk2 will take tens of years, even after India has certified a 4th generation fighter aircraft could be borne out of some prejudices. Time now to grow out of that, engage with indigenous industry & realise it's suppressed potential.

Kartik · Post by **Kartik** » 26 May 2020 23:05

So good to have HVT back on Twitter. He single handedly can demolish almost any BS against the Tejas apart from the other gyan he gives.

srai · Post by **srai** » 27 May 2020 05:11

Part of the production and induction timelines is also dependent on the IAF. At what point is the IOC considered good enough to induct? And how many quantities will be procured at IOC?

The other part is the GoI funding for the production setup and execution. A big roadblock is their procurement red-tape.

From the design, development and production pov, DRDO/ADA/HAL sound very confident in the timelines announced.

sankum · Post by **sankum** » 28 May 2020 23:04

https://hal-india.co.in/Tender_Details. ... ivkey=MTY=

HAL tyre tender for Tejas mk2.

MTOW 18200kg
Normal TOW 17500kg
High Altitude TOW 13500kg

Normal landing weight 12500kg
Maximum landing weight 13000kg
Emergency landing weight 17000kg.

basant · Post by **basant** » 29 May 2020 00:02

srai wrote:Part of the production and induction timelines is also dependent on the IAF. At what point is the IOC considered good enough to induct? And how many quantities will be procured at IOC?

The other part is the GoI funding for the production setup and execution. A big roadblock is their procurement red-tape.

From the design, development and production pov, DRDO/ADA/HAL sound very confident in the timelines announced.

It is widely accepted that Indian Army was saved (in 1947) from the pacifist leader by Pakistan's aggression in Kashmir. China may save Tejas by helping decimation of bureaucratic roadblocks in procurement of indigenous equipment once and for all.

Kartik · Post by **Kartik** » 29 May 2020 00:24

As per Anantha Krishnan, the IAF now wants the term Medium Weight Fighter (MWF) to be dumped and go back to Tejas Mk2 or LCA Mk2.

Rakesh · Post by **Rakesh** » 29 May 2020 00:32

Did he tweet this or did he put out a news article? Any link?

RKumar · Post by **RKumar** » 29 May 2020 00:36

Kartik wrote:As per Anantha Krishnan, the IAF now wants the term Medium Weight Fighter (MWF) to be dumped and go back to Tejas Mk2 or LCA Mk2.

Seems like they want to protect the imports of medium category fighter. if they name LCA Mk2 specifically as MWF, then no more imports. They are trying to open a gap for future, bright minds at work

Light category is exclusively Tejas so no imports for this category.

Rakesh · Post by **Rakesh** » 29 May 2020 00:37

Found the tweet!

We are 20 pages into this thread. I am not changing the title thread now. When a new thread is started, will revert to the term Tejas Mk2.

https://twitter.com/writetake/status/12 ... 26400?s=20 ----> The advanced version of LCA which was known as Medium Weight Fighter (MWF) will now be Tejas Mk II or LCA Mk II as called earlier. The name MWF has been dropped. Eventually, this programme will get an appropriate name at the right time.

nam · Post by **nam** » 29 May 2020 00:53

Rakesh wrote: https://twitter.com/hvtiaf/status/12636 ... 16097?s=20 ---> It's not anticipated to take long. A perception that Mk2 will take tens of years, even after India has certified a 4th generation fighter aircraft could be borne out of some prejudices. Time now to grow out of that, engage with indigenous industry & realise it's suppressed potential.

I always wondered about this trait of us. Very difficult for Indians to believe that Indians could create good things.
On the other side of the spectrum, you have a nation which was created from the same "race" of people, who are super confident that a Chinese jet was actually created by them and it is almost human civilization's greatest endeavor.

It amazes me that IAF is ready to keep flying 50 year old jet, than induct more of FOC version with a top notch radar, BVR, composite & engine.

Sometimes I feel, there is a fear in IAF that we might actually succeed in making a good jet and that would close the door to flying in a TFTA European or American fighter. Like a mango desi's dream of owning a Mercedes/BMW/Audi/Jag/RR etc..

Rakesh · Post by **Rakesh** » 29 May 2020 01:18

agupta wrote:Puzzled by your inference that it was the IAF that drove this... Anantha's tweets do not ascribe any ownership re. this shift ! From a different source, then ?

https://twitter.com/ungliwallah/status/ ... 17893?s=20 ---> I suspect IAF panicked at calling it MWF because GoI would question need for MMRCA given indigenous medium weight fighter so asked for a rename back to innocuous Mk 2.

basant · Post by **basant** » 29 May 2020 01:34

Rakesh wrote:
agupta wrote:Puzzled by your inference that it was the IAF that drove this... Anantha's tweets do not ascribe any ownership re. this shift ! From a different source, then ?
https://twitter.com/ungliwallah/status/ ... 17893?s=20 ---> I suspect IAF panicked at calling it MWF because GoI would question need for MMRCA given indigenous medium weight fighter so asked for a rename back to innocuous Mk 2

It's too late to play such tricks, opposition will roast even if the move is sane, which isn't. Unless they are going to change the specs to previous Mk2 for which someone should take blame for getting models wrong, which neither ADA nor HAL will never do when we are already talking of metal cutting dates. If government wants to buy MRCA, it will say so and has been saying so.

Ironically, the biggest push for indigenization comes from falling GDP, necessity for MII and urgency due to tensions at the borders. Government will have to look for spending money within India.

Kartik · Post by **Kartik** » 29 May 2020 02:15

agupta wrote:
Kartik wrote:As per Anantha Krishnan, the IAF now wants the term Medium Weight Fighter (MWF) to be dumped and go back to Tejas Mk2 or LCA Mk2.
Puzzled by your inference that it was the IAF that drove this... Anantha's tweets do not ascribe any ownership re. this shift ! From a different source, then ?

Can you think of a good reason why ADA or DRDO would ask that the program be again called Tejas Mk2 after they themselves were calling it MWF saying it was no longer a light fighter? As someone replied on Twitter, it would seem that the IAF may not want an impression that the MWF could replace the MRCA program and hence the shift back to the Mk2 terminology.

But of course, we could be wrong and it could simply be an ADA/DRDO thing.

ramana · Post by **ramana** » 29 May 2020 03:55

Rakesh wrote:
agupta wrote:Puzzled by your inference that it was the IAF that drove this... Anantha's tweets do not ascribe any ownership re. this shift ! From a different source, then ?
https://twitter.com/ungliwallah/status/ ... 17893?s=20 ---> I suspect IAF panicked at calling it MWF because GoI would question need for MMRCA given indigenous medium weight fighter so asked for a rename back to innocuous Mk 2.

The present PMO team is quite savvy about military products and can't pull wool over their eyes.
My thinking is the MMRCA is being talked about to not deny the service fantasies.

With MWF there is no need for it and further goes against the grain of AtmaNirBar Bharat.