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

[srin]

they should have continued on...while purchasing the f35b for their carriers.
buying US stuff generation after generation...despite having so much domestic tech.

i expect Soko to push on and do it, they do not give up so easily.

Reminds me of Avro Arrow case. We shouldn't do the same mistake, sacrificing Tejas for SEF, AMCA for F35/FGFA etc. Need to carry on. Interesting to see we aren't the only ones confronted with import vs design on your own choice

[brar_w]

they should have continued on...while purchasing the f35b for their carriers.
buying US stuff generation after generation...despite having so much domestic tech.

i expect Soko to push on and do it, they do not give up so easily.

viewtopic.php?f=3&t=7625&p=2256809#p2256809

[Cain Marko]

I'm just wondering....

Is this a result of the kaveri snecma coming through?
Will macaroni come with champagne?

Mithai and Champagne deliveries have already begun from my side...

Bees saal der ho chukee hai, lekin aapako mil gaya...ab shikaayat mat karo!!!

Oh no Saar, akhri dum Tak shikayat aur rnd andolan jari rahega. Brfites will never forget nor let you forget...

[Haridas]

Also brace for retaliation by dalals and chamchas soon. And from the retired and near-retired who have fought and mocked Tejas for their entire careers.

You mean the retards and semi retards who rdy to sell their motherland for money or false ego !! (pun intended)

[Haridas]

NS is a good DM but the DM's mettle will only be tested in a war and not just by procurement. In my books Y B Chavan and old George remain higher.

Good to hear from you Deejay ji. You have high standards indeed, on the scale of which many ex DM like A.K.Anthony , Pranab Mukarjee, Jaswant Singh, Chandrashekher, Mulayam Singh, sharad pawar, VP Singh, Krishna menon etc. will appear as airy ghosts or worst - traitor(s).

[Haridas]

Why Mk2 needs a bigger/taller vertical tail stabilizer? Because of increased length and weight or something to do with aerodynamics/drag/stability?

Because of its high AoA and longer length . Tail should be high enough to provide sufficient area for yaw control in spite of turbulent delta wing downwash.

[Haridas]

we could buy 36 basic Pakfa like the chinese have purchased 36 Su35 and 'study' it properly ...whatever money and efforts IAF wanted to spend bringing the pakfa upto their liking is best expended on the AMCA.

India is part of design group of PakFA.

Since when? Didn't see any report.
Otoh heard report where iaf upset that its pilots can't even ride as copilot even once.

[Neshant]

Japan's Scraps Domestic Development of 5th Generation Stealth Fighter Jet
https://thediplomat.com/2018/03/japans- ... ghter-jet/

Has F-35 production cancelled a domestic industrial product ?
A lesson to learn here.

American F-16s killed the Lavi
American F35 may have killed this too.

However unlike Israel and Japan we are not that close to Amreeka.
We must have more domestic products and more control of our destiny.

Japan launched their Shinshin program as a bargaining tool for price/offset negotiations of American combat aircraft more than anything else.

They were never really serious about developing it to production.

Likewise, expect India to attempt development of a 150 seater regional airliner in the years ahead just as China has.

Whether it will be developed to production or merely used as a bargaining chip during foreign plane purchases remains to be seen.

Once China has completed the development of it's passenger airliner, Boeing/Airbus/Bombardier/Embrarer won't be able to charge them an arm and a leg as they do with India because China can always turn to it's domestic alternative - even if it's not the best.

India has done a poor job of developing it's civilian and military aerospace R&D capability so far sadly costing the country great sums of money.

[JayS]

^^ Take the discussions on other than Tejas Mk2, to relevant thread. Thanks.

[Raman]

Why Mk2 needs a bigger/taller vertical tail stabilizer? Because of increased length and weight or something to do with aerodynamics/drag/stability?

Because of its high AoA and longer length . Tail should be high enough to provide sufficient area for yaw control in spite of turbulent delta wing downwash.

Yes to higher AoA, but no to longer length. The longer fuselage (by itself) actually requires a smaller tail because the additional length adds to tail volume coefficient (i.e., "leverage" of the tail surface). Same reason why the small 747SP has a taller tail than the standard 747.

[Philip]

Tejas MK-2 as a stealth fighter will be a huge "leapfrog"
moment for our desi aerospace ambitions.It will have huge export potential too if there is an engine alternative, the TVC EJ instead of the GE 414 becos of US arms sales policy towards certain customer nations.We should develop alternative prototypes for EJ TVC engines as well as the GE 414.Developing a 4+ gen. LCA MK-2 )by 2025 in the era of 5th-gen stealth is as said before going " back to the future".

[SaiK]

The valve has dual role for parking and emergency braking. The valve is used in the brake system during parking and emergency braking. It shall supply hydraulic power to the brakes for parking the aircraft and it shall be able to modulate the brake pressure as per the pilot input transmitted through a cable. The valve shall be securely mounted to the aircraft structure. Pilot can operate the valve for braking through a cable connected between cockpit control and valve handle. For emergency braking, the pilot pulls the control cable in-order to apply brakes progressively and for parking, pilot pulls the cockpit handle for a travel of 35mm and turns 90 deg clockwise to lock. The hydraulic pressure supply to the progressive pressure control valve is from a dedicated accumulator. The valve shall be so designed that the leakages during fully released condition and parked condition should be zero so that the cumbersome process of accumulator charging is avoided daily.

Q: what is changing in Mk2?

[ramana]

Tejas MK-2 as a stealth fighter will be a huge "leapfrog"
moment for our desi aerospace ambitions.It will have huge export potential too if there is an engine alternative, the TVC EJ instead of the GE 414 becos of US arms sales policy towards certain customer nations.We should develop alternative prototypes for EJ TVC engines as well as the GE 414.Developing a 4+ gen. LCA MK-2 )by 2025 in the era of 5th-gen stealth is as said before going " back to the future".

Don't do that. Sounds futuristic delay requirement.

What IAF needs is the Tejas Mk2 the design is undergoing completion.

Look at how many unavailable things you want in this:
1) Stealth airframe
2) TVC EJ
4) unstated new FCS, weapons
Sure dream but please don't tag Tejas Mk2 to that dream, for it will become nightmare.

[Indranil]

Because of its high AoA and longer length . Tail should be high enough to provide sufficient area for yaw control in spite of turbulent delta wing downwash.

Yes to higher AoA, but no to longer length. The longer fuselage (by itself) actually requires a smaller tail because the additional length adds to tail volume coefficient (i.e., "leverage" of the tail surface). Same reason why the small 747SP has a taller tail than the standard 747.

+1.

Also, it is difficult to say without CFD, windtunnel and actual flight testing. LCA Trainer turns out to be stable than the Tejas at higher AoA. The former is cleared to 26 degrees and the latter to 24. They have the same length and tail size. Turns out the larger keel of the trainer aids in the stability.

[Cosmo_R]

India is part of design group of PakFA.

Since when? Didn't see any report.
Otoh heard report where iaf upset that its pilots can't even ride as copilot even once.

Yes zip. They won't let the IAF near the a/c even after we poured $295MM into it
Whoops wrong thread

[Kartik]

Yes to higher AoA, but no to longer length. The longer fuselage (by itself) actually requires a smaller tail because the additional length adds to tail volume coefficient (i.e., "leverage" of the tail surface). Same reason why the small 747SP has a taller tail than the standard 747.

+1.

Also, it is difficult to say without CFD, windtunnel and actual flight testing. LCA Trainer turns out to be stable than the Tejas at higher AoA. The former is cleared to 26 degrees and the latter to 24. They have the same length and tail size. Turns out the larger keel of the trainer aids in the stability.

The Tejas Mk2 modified canopy shape that we've seen in a paper also indicates that it is slightly higher and more like a trainer, than the existing fighter design. Which means, higher controllability at higher alpha. But the higher canopy may require the larger tail for the control at higher beta (yaw) angles.

[Raman]

Is the canard configuration confirmed? If so, placement of the canards will also affect the area ruling of the canopy and spine. The canopy shape will likely have to be different than indicated in that cfd study.

[Philip]

Ok, understood the dev. delay factor.Provided it arrives asap and is produced around 24 /yr..If it repeats MK-1/1A timeframe, it will be found to carry an obsolescence factor that may reduce end-user orders in favour of more capable 4++ fighters or 5th- gen birds.
If a parallel programme to add stealth to the basic MK-2 concept is undertaken simultaneously, if significant headway has already been been made on the MK-2 of which little info has been forthcoming, it could produce a couple of prototypes which could be the later batches of the MK-2.

[ramana]

Ok. Parallel program. Got it. More like Mk3.

[Indranil]

+1.

Also, it is difficult to say without CFD, windtunnel and actual flight testing. LCA Trainer turns out to be stable than the Tejas at higher AoA. The former is cleared to 26 degrees and the latter to 24. They have the same length and tail size. Turns out the larger keel of the trainer aids in the stability.

The Tejas Mk2 modified canopy shape that we've seen in a paper also indicates that it is slightly higher and more like a trainer, than the existing fighter design. Which means, higher controllability at higher alpha. But the higher canopy may require the larger tail for the control at higher beta (yaw) angles.

Actually, this study is a few years old now. This shape was great for transonic and supersonic performance but was detrimental to high AoA performance as the AoA at which the pitch-up happens came down. So, as we have been saying, it is not so easy to say whether a taller tail will help with AoA.

Is the canard configuration confirmed? If so, placement of the canards will also affect the area ruling of the canopy and spine. The canopy shape will likely have to be different than indicated in that cfd study.

Cleared for WT testing. All CFD analysis done.Canards almost always help with the area ruling. In this case, it really helps to smooth out the kink after the canopy.

When these analysis are made public, you will some other nice touches too.

[srai]

^^^
0.5m or 1m plug with canard?

[Indranil]

I think it is still a 0.5 mtr plug. The mind boggles at the number of things that should have done. With the plug, the CG moves. With the canard the CP moves. the mouth of the inlet is tied to the LE of the wing, so that should move with the wing. I have already seen studies where the curvature of the lip has been optimized for better pressure recovery. Actually, if that study is implemented, they will have two different radii, one for the top half of the lip, and the other for the bottom half. Te shape of the inlet itself has been optimized for the airflow to the engine and for better form drag. The canopy and the are behind the canopy will change. The pylons will change and the fairing for the flaperons will also change. Almost all the tanks will change for higher capacity, lower drag and lower interference. There will be touches everywhere and a big touch somewhere.

It is going be quite a refined product.

[sankum]

Indranil,
Then the MTOW of Tejas mk2 will be 15000 Kg and fuel will be just above 2500 Kg not much difference from mk1.

[Singha]

why are the actuator fairings of tejas so big ?

will these refinements reduce drag? usually fighters like to speed up from 750kmph type eco patrol speed to mach 1.5 before launching bvr AAMs...will it help in this acceleration phase ?

they say a f22 accelerates so fast into supersonic , chase planes like f16 had to use AB to keep up

[Zynda]

I have already seen studies where the curvature of the lip has been optimized for better pressure recovery. Actually, if that study is implemented, they will have two different radii, one for the top half of the lip, and the other for the bottom half.

IR, are these studies available in public domain? Would be interested in glancing through them.

[Haridas]

Because of its high AoA and longer length . Tail should be high enough to provide sufficient area for yaw control in spite of turbulent delta wing downwash.

Yes to higher AoA, but no to longer length. The longer fuselage (by itself) actually requires a smaller tail because the additional length adds to tail volume coefficient (i.e., "leverage" of the tail surface). Same reason why the small 747SP has a taller tail than the standard 747.

Thanks for pointing out. I took the first order effect that is based on geometry scale up creating shadow on tail surface.
Otoh the added length is ahead of CG and wing, so IMHO it adversly undercuts tail volume coefficient, requiring larger tail height.

[Haridas]

why are the actuator fairings of tejas so big ?

Actually big is aerodynamically superior. Contributes like anti shock device.

[JayS]

Yes to higher AoA, but no to longer length. The longer fuselage (by itself) actually requires a smaller tail because the additional length adds to tail volume coefficient (i.e., "leverage" of the tail surface). Same reason why the small 747SP has a taller tail than the standard 747.

Thanks for pointing out. I took the first order effect that is based on geometry scale up creating shadow on tail surface.
Otoh the added length is ahead of CG and wing, so IMHO it adversly undercuts tail volume coefficient, requiring larger tail height.

In fact, wouldn't the added length push CG away from tail increasing lever arm and thus tail volume..?

What Indranil said is right. Thumb rules aside, we are talking of refinements here which are coupled with multiple effects. Its difficult to say which causes which without knowing some hard data. Multiple things are under consideration. We know only a little.

[JayS]

why are the actuator fairings of tejas so big ?

will these refinements reduce drag? usually fighters like to speed up from 750kmph type eco patrol speed to mach 1.5 before launching bvr AAMs...will it help in this acceleration phase ?

they say a f22 accelerates so fast into supersonic , chase planes like f16 had to use AB to keep up

Yes, positive impact on drag an in turn on acceleration and range. We have seen some numbers already, due to canopy reshaping for example - IIRC 6% reduction in drag and 20% increase in transonic acceleration.

The fairings are used to smooth out area curve at the end, there is sudden jump when wings end. These fairings or anti-shock bodies help smooth out the transition. Remember though, they reduce wave drag but increase base drag. But the overall impact is positive.

[Indranil]

I have already seen studies where the curvature of the lip has been optimized for better pressure recovery. Actually, if that study is implemented, they will have two different radii, one for the top half of the lip, and the other for the bottom half.

IR, are these studies available in public domain? Would be interested in glancing through them.

They were public for a short while and then the links stopped working

[Indranil]

Indranil,
Then the MTOW of Tejas mk2 will be 15000 Kg and fuel will be just above 2500 Kg not much difference from mk1.

The internal fuel is being significantly increased. So the fuel load of almost all DTs. The DTs are optimized for actually lower drag and interference with the other payloads in spite of having larger capacity.

[Kartik]

Actually, this study is a few years old now. This shape was great for transonic and supersonic performance but was detrimental to high AoA performance as the AoA at which the pitch-up happens came down. So, as we have been saying, it is not so easy to say whether a taller tail will help with AoA.

This study was presented in August 2015. So yes, its been 2.5 years since then, plenty of time to look at it more deeply and figure out whether it was feasible from all aspects or not. Is your info on this shape not being good from a pitch-up alpha pov relatively recent?

So, what I can gather based on what you've said is that the refined canopy shape shown here is not what is being tested now in the wind tunnel. If the canards are part of the new config that went through CFD analysis, then we would see a canopy optimized for that canard Mk2 design, which will then have to be more or less like the existing shape but with a smoother curvature, since the canards will most likely be placed just aft of the canopy and below it. The increase in the cross-sectional area as a result will mean that the canopy will need to taper off much more than in the proposed canopy shape below..so more or less like the existing design. the smoothening out of the cross-sectional area as a result of the canards will then be the contributing factor towards drag reduction.

Cleared for WT testing. All CFD analysis done.Canards almost always help with the area ruling. In this case, it really helps to smooth out the kink after the canopy.

When these analysis are made public, you will some other nice touches too.

What is going to be most interesting will be to see how the design is changed to accomodate the canards. the reason for that is that space will be needed to be made available for embedding the actuators for the all-moving canards; assuming the Mk2 gets all-moving canards and not fixed ones like those on various Mirage and Kfir jets.

So the 0.5m plug aft of the canopy will likely be where the canard will be attached to the fuselage (still hoping for it to be a 1m plug).. Will a small new "cheek" be added to the design, sort of how it was for the LCA Navy Mk2 to fit the actuators or will it be flush with the fuselage? Access to the cockpit must not be impeded either.

Might it look more like the LCA Navy Mk2 minus the LEVCON with the canards placed just below the cockpit? the LCA Navy Mk2 was 1m longer than the Tejas Mk1.

[Indranil]

Actually, this study is a few years old now. This shape was great for transonic and supersonic performance but was detrimental to high AoA performance as the AoA at which the pitch-up happens came down. So, as we have been saying, it is not so easy to say whether a taller tail will help with AoA.

This study was presented in August 2015. So yes, its been 2.5 years since then, plenty of time to look at it more deeply and figure out whether it was feasible from all aspects or not. Is your info on this shape not being good from a pitch-up alpha pov relatively recent?

IIRC it was the conclusion in the same paper. Also this paper was published 2.5 years ago. You can safely add an year to when the work was actually done.

So, what I can gather based on what you've said is that the refined canopy shape shown here is not what is being tested now in the wind tunnel. If the canards are part of the new config that went through CFD analysis, then we would see a canopy optimized for that canard Mk2 design, which will then have to be more or less like the existing shape but with a smoother curvature, since the canards will most likely be placed just aft of the canopy and below it. The increase in the cross-sectional area as a result will mean that the canopy will need to taper off much more than in the proposed canopy shape below..so more or less like the existing design. the smoothening out of the cross-sectional area as a result of the canards will then be the contributing factor towards drag reduction.

Actually, they are going to have an enlarged shape behind the canopy very similar to what you are seeing here. They can delay the pitch up using the canards. Between the plug, bulge and the canard, the area curve has been smoothened considerably. Mk2 will have considerably better transonic performance.

What is going to be most interesting will be to see how the design is changed to accomodate the canards. the reason for that is that space will be needed to be made available for embedding the actuators for the all-moving canards; assuming the Mk2 gets all-moving canards and not fixed ones like those on various Mirage and Kfir jets.

So the 0.5m plug aft of the canopy will likely be where the canard will be attached to the fuselage (still hoping for it to be a 1m plug).. Will a small new "cheek" be added to the design, sort of how it was for the LCA Navy Mk2 to fit the actuators or will it be flush with the fuselage? Access to the cockpit must not be impeded either.

All moving active canards, but no cheeks.

Might it look more like the LCA Navy Mk2 minus the LEVCON with the canards placed just below the cockpit? the LCA Navy Mk2 was 1m longer than the Tejas Mk1.

Actually the Navy Mk2 design is almost ready, definitely more ready than the Tejas Mk2. But Navy is in a catch 22 situation. IAC and IAC2 have different launching systems. It has asked ADA to help fix the Mig-29k structures using the LCA Navy Mk1 experience. The structural changes required on the Mig-29k are extensive. Navy tender for 56 twin engine fighters is unlikely to cost less than 12 billion dollars. Where is the money?

Meanwhile, IAF has run out money for committed capital acquisitions for this year. NDA-2 has been even more stingy than UPA-2 in increasing budgetary allotment for the forces, in spite of larger pension bill. God knows who plans anything in this country. But yes, one thing is sure the scientist of DRDO are the only ones who get blamed for the entire mess!

[prabhug]

why not convert LCA Navy Mk2 to LCA AF Mk2 by changing landing gear

[Zynda]

IR, are these studies available in public domain? Would be interested in glancing through them.

They were public for a short while and then the links stopped working

Yup...they are not working. Wish NAL starts archiving these presentations.

[JayS]

They were public for a short while and then the links stopped working

Yup...they are not working. Wish NAL starts archiving these presentations.

Zynda, check your mail.

IR, add "oldsite." ahead of the links. They still work.

[Kartik]

Thanks IR.

So flush mounted canards. Any chance that ADA will release images of the configuration being studied?

Actually the Navy Mk2 design is almost ready, definitely more ready than the Tejas Mk2. But Navy is in a catch 22 situation. IAC and IAC2 have different launching systems. It has asked ADA to help fix the Mig-29k structures using the LCA Navy Mk1 experience. The structural changes required on the Mig-29k are extensive. Navy tender for 56 twin engine fighters is unlikely to cost less than 12 billion dollars. Where is the money?

But detailed design activities stopped a while ago and LCA Mk1 testing stopped completely after the IN basically stopped funding.

I didn't get what the catch 22 situation is. What different launching systems on IAC1 and IAC2 are you referring to? IAC1 with STOBAR vs IAC2 with CATOBAR?

And why should ADA help fix the MiG-29K? They don't own the IP to it. Why not go ask MiG Corp which has been issuing press releases that nothing is wrong with the MiG-29K in IN service?

[Indranil]

Yeah. Currently, there is no fighter other the F-35 which is certified for both STOBAR and CATOBAR. Everybody else has done studies. Some like the Sea Gripen have only done studies on both.

No force will call out deficiency of its arms in public. Everybody goes about cleaning the mess internally. So IN is not doing anything wrong. They must have reached out to MIG. You can understand what MIG's response must have been for IN to then turn to ADA. I have no problems with IN is doing there.

I am only sad that there is some truth to the Ajai Shukla report.

[Philip]

I agree.Any 29K issues is MIG's responsibilities.If ADA resolves the same ,send MIG a big fat bill for consultancy! Remember that we did impose delay penalties for some glitches- sorted out ,on the first batch of Talwars.

[Kartik]

Yeah. Currently, there is no fighter other the F-35 which is certified for both STOBAR and CATOBAR. Everybody else has done studies. Some like the Sea Gripen have only done studies on both.

No force will call out deficiency of its arms in public. Everybody goes about cleaning the mess internally. So IN is not doing anything wrong. They must have reached out to MIG. You can understand what MIG's response must have been for IN to then turn to ADA. I have no problems with IN is doing there.

I am only sad that there is some truth to the Ajai Shukla report.

the IN could ask Dassault and Boeing to prove out their studies of being able to launch from STOBAR carriers by first demonstrating it off INS Hansa's land based test facility and then prove it aboard INS Vikramaditya.

the MiG-29K fault rectification is sort of going by the set trend now. Buy Russian ware, find out issues in the field and then after being told by Russian firms to either pay ransom to fix issues that shouldn't have arisen, or being given the run around, find a local DRDO agency to fix their faults. MiG should be the one paying for the issue rectification. They are the IP owners. I mean the RuN is also going to find out that the MiG-29KR has issues, so it will eventually need to be fixed for their fleet as well.

Who is going to be responsible for certifying the fixes that ADA/DRDO will likely come up with? CEMILAC?

Only good thing that will come out of this experience is that it will pretty much completely rule out any MiG-29K derivative from the MRCBF contest.