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

[kvraghav]

What a beaut !

That said, there's something odd about it - look just to the left of the Nausena word....how is the contrail/vortex visible through the rudder ? Are my old eyes tired or is this PS enhanced ?

I think this has been a error when some one worked on the image. PS issues.

[souravB]

....

These are excellent photos. Highlighting excellent build quality for 4th gen bird. Certainly comparable to solah-50s. Specifically for NP1, as a TD too, it is definitely at par with eighteen.

[Indranil]

What a beaut !

That said, there's something odd about it - look just to the left of the Nausena word....how is the contrail/vortex visible through the rudder ? Are my old eyes tired or is this PS enhanced ?

I think this has been a error when some one worked on the image. PS issues.

There are no PS involved. Your eyes are playing tricks.

Nothing is viewable through the rudder. The vortex contrail that you are referring to is from the starboard wingtip. It lies in front of the rudder. The contrail from the port side wingtip can also be seen just behind the engine nozzle.

[Karan M]

Indranil - check the IAF thread for more on Astra.

[srai]

[srai]

[Neela]

A UK based review of LCA Tejas. Pretty shallow but it is meant for Youtube audience.

[mody]

Mody, do you have a link for the same, or is it chai-source? TIA.

Karan link to article by Shiv Arror, that very specifically mentions that the Rafeal will have the option of integrating the Astra missile, as well as Brahmos-NG (Point no. 4). It will also carry the Israeli Spice family of bombs and in future any other similar Indian systems.

https://www.dailyo.in/variety/rafale-ai ... 18157.html

[Barath]

A UK based review of LCA Tejas. Pretty shallow but it is meant for Youtube audience.

The Follow Up

TEJAS Aircraft Aerodynamics Analysis - The Swedish Connection?
https://www.youtube.com/watch?v=adr6-vK ... e=youtu.be

HVT adds that the followup doesn't have any definite info , but that on the first video, canards were indeed consdired for LCA Mk1 but given up due to lack of confidence in the post sanctions period. However, the confidence is there, now https://twitter.com/hvtiaf/status/1254581263614087168

[Karan M]

Thanks Mody, great find.

[ks_sachin]

A UK based review of LCA Tejas. Pretty shallow but it is meant for Youtube audience.

I personally found it rather irritating. A lack of research into the history and AF requirements that impacted the design considerations. People would get the impression that ADA went and designed something out of thin air!!!!

Constipation of thought and a diarrhoea of words!!! After the first video did not bother with the second...

Indranil’s article is the gold standard...

[Uttam]

GE Bet on Aviation to Pull Through Its Troubles; Then Coronavirus Hit

[Mods: please feel free to delete or move if not appropriate for this thread]

I never post on Military Issues as I know very little about them, though I love to read these threads. But I do have some expertise in Economics, Finance and specially with issues related to Bankruptcy laws in US. I am here just to share my thoughts about some serious threat faced by Tejas if GE goes under.

If GE goes under, then all bets are off about its jet engines. The bankruptcy laws do not protect any signed contracts. The only contracts that have any meaningful value when a firm goes under bankruptcy protection are Debt contracts. This global pandemic therefore presents a very serious threat to all fighter planes including Tejas that are heavily dependent on GE's jet engine. History is replete with example where bankruptcy of one firm led to very serious contagions for other projects and firms that were dependent on the former. Bankrupt firms are often sold in piece and many of these pieces are picked up by private equity firms. Such private equity firms don't really believe in long term reputation building or preserving long-term commercial relations. They just want to make a quick buck and will go to any lengths to do so. US govt. can easily restrict sale of such tech to any nation but can't really force private equity firms to make such sales. Overall, the Tejas and other clients of GE aviation will face very serious challenges if GE goes bankrupt.

[nachiket]

GE engine division is not going anywhere. Even if the company goes under the Engine division will get hived off into a separate firm or get snapped up by another company. There's just too much bleeding-edge IP and a huge market share (both civilian and military) to let go of. Just think of the number of Boeing aircraft which use GE engines - all Boeing 737's (CFM is a GE-Safran JV) and nearly all 777's, half the 787's etc plus many Airbus aircraft (half the new A320 Neo's for example). The USN's entire Super Hornet fleet is dependent on the same engines that the Tejas Mk2 will use. All F-16 blk 50's everywhere use GE engines (the 52's use PW). Too big to fail.

[Kartik]

This one bbn is clicked by Mao sir. First flight of NP2 with tail hook integrated.

What a beaut !
That said, there's something odd about it - look just to the left of the Nausena word....how is the contrail/vortex visible through the rudder ? Are my old eyes tired or is this PS enhanced ?

There are 2 contrails- the one above is from the right wing and is passing over the rudder as would be expected and the lower contrail is from the left wing.

Real pic, not PS

[Kartik]

What a beaut !

That said, there's something odd about it - look just to the left of the Nausena word....how is the contrail/vortex visible through the rudder ? Are my old eyes tired or is this PS enhanced ?

I think this has been a error when some one worked on the image. PS issues.

Absolutely not. Look closely before calling it a PS work.

[kvraghav]

I think this has been a error when some one worked on the image. PS issues.

Absolutely not. Look closely before calling it a PS work.

My mistake. Mistook the wake from below the right wing to that generated from the left. The color of the background being same as blue patches on the rudder did not help my case.

[Cain Marko]

Can't the mk1 carry an spj on the ldp station while still carrying 6 AAMs and CFT? If course dualk racks are always useful..

There were reports that the Ideal position of SPJ was one of the outboard pylons

Thank you. I remember the conversation now. Makes sense.

[Haridas]

There are no PS involved. Your eyes are playing tricks.

Nothing is viewable through the rudder. The vortex contrail that you are referring to is from the starboard wingtip. It lies in front of the rudder. The contrail from the port side wingtip can also be seen just behind the engine nozzle.

Not from starboard wingtip (too high for it) but from forward slats.

[basant]

I don't know if we have discussed this here. This was a ferry flight from Bangalore to Jaisalmer.

They landed with 800 kg of fuel left. Flying at around FL 280-290 (28000-29000 feet). Higher cruising altitude will lead to higher endurance and range. Current flight ceilings during ferry flights are regulated by DGCA. So, brochure ferry range and endurance without refueling should be around 2800 kms and over 3.5 hours.

2800kms!

I faintly remembered and tried to find the post referring to the same when Tejas was on enroute to Bahrain. All I could find was your own post referring to flying to Jodhpur with 500l to spare. Can't be happier!

A UK based review of LCA Tejas. Pretty shallow but it is meant for Youtube audience.

I personally found it rather irritating. A lack of research into the history and AF requirements that impacted the design considerations. People would get the impression that ADA went and designed something out of thin air!!!!

Can't agree more. The one good thing I found on the post was the information shared by Marcos' as a reply to Amused Observer. I am posting it here as it may refresh the data and some may find it useful.

@Amused Observer Following are the Indian avionics in Tejas. Correct me if i am wrong anywhere :
1.RCI fibre-optic gyro based inertial navigation system integrated with Galileo/GLONASS/GPS/NavIC satellite guidance and tactical air navigation (TACAN) system

2.VHF/UHF radio communication with in-built counter-countermeasure system, supports air-to-air and air-to-ground via secure datalink

3. Digital weapon management system (DWMS), compatible with NATO and Russian standards

4.-64-bit PowerPC dual modular redundant MIL-STD-1553B databus and open architecture mission computer

5. Ground proximity warning and terrain referenced navigation system

6. VHF omnidirectional range–instrument landing system (VOR–ILS)

7. Computer controlled flight utility system and management system (USMS)

8. Hybrid environmental monitoring and control system (EMCS)

9. Aircraft health and usage monitoring systems (HUMS)

10. MIL-STD-1760C stores management system

11. Fail-operational/fail-safe air data system

12. computational intelligence based pilot help emergency and autoland system with ground station controls.

13. Identification friend or foe (IFF)

14.Chaff, jaff and flares dispenser

15. Night-vision goggles compatible glass cockpit

16. head-up display (HUD).

Within a couple of years, there will be more coming in..such as the MAYAVI EW System, UTTAM Aesa radar and Onboard Oxygen Generator system.

[Indranil]

There are no PS involved. Your eyes are playing tricks.

Nothing is viewable through the rudder. The vortex contrail that you are referring to is from the starboard wingtip. It lies in front of the rudder. The contrail from the port side wingtip can also be seen just behind the engine nozzle.

Not from starboard wingtip (too high for it) but from forward slats.

No sirjee. It is actually from the wingtip. Let me explain. The vortex at every slat originates at the root (as is expected of any delta). So the vortex at the outermost slat is also originated at its root (not near wingtip). In the case of Tejas, these vortices are pretty large by design (large enough to affect the reattachment of the main vortex on the main wing). They break down pretty fast as well. The contrail that you see in the above picture cannot be created by the vortex generated by the LE slats.


The contrail that you are seeing here is from the wingtip. It originates from the notch on the LE just inboard of the lights, where the tip of the outermost slat would meet in the fully retracted position. You can see the contrail here.

^^^ exists on both wingtips, but can be viewed more clearly near the starboard wingtip.


on both wingtips.

[Vivek K]

Dancing like an Apsara!! What a beauty!

[ramana]

Karan,

...

Anyways, I went back to have some more chai. For Mk1 and Mk1A they are seriously considering 4 BVRAAMs + 2CCMs + centerline tank. But that is nothing new. That config has been on static display. No talks of dual racks. At least that flavor of chai was unavailable to me.

What would be the take off weight of that weapons load? And as % of max takeoff please.

[sankum]

Clean take off weight of Tejas mk1 with 2 CCM is 9800 kg and Tejas mk1a is 9900kg.

4 Derby ER with 40 Kg Nato standard launcher will be 4*(118kg+40kg)=632kg

4 Astra mk1 with R 77 launcher weighing 60 kg will be 4*(154kg+60kg)=856kg

725 litre centre EFT will weigh 725*0.8/0.9~ 640kg.

Tejas mk1a with derby=11170kg(81% of MTOW)

Tejas mk1a with Astra=11400kg(83% of MTOW)

Whether Optronic pod will be carried for passive air to air targeting add 200kg.

MTOW @13800kg.

[sankum]

Exclusive AMRAAM launcher weighs only 28 kg as it does not carry nitrogen cooling bottle for IR seeker of CCM in which case it weighs 40kg.
Astra launcher is being developed. Don't know if it dual for CCM or only for Radar guided BVR.

[mody]

Clean take off weight of Tejas mk1 with 2 CCM is 9800 kg and Tejas mk1a is 9900kg.

MTOW @13800kg.

Any source that says MK1A will weigh 100 Kgs more than the MK1 version? Thanks.

[sankum]

Partial infoboard in defexpo 2020 posted in this forum by shobhits.
Its the weight of jamming pod carried by Tejas mk1a.

[Bharadwaj]

OT but HVT Sir's twitter gone?

[basant]

OT but HVT Sir's twitter gone?

Appears to be the case!

[sankum]

.
Harsh Vardhan Thakur on Twitter: "Thanks Tweeple. Moving forward ...

He retired.

[Venu]

.
Harsh Vardhan Thakur on Twitter: "Thanks Tweeple. Moving forward ...

He retired.

But only a couple of weeks ago, when someone asked him on twitter about when he is hanging boots, his reply was something in the lines of 'always young', implying no idea of doing it anytime soon.

Is it because any issue with HAL? Or is he just retrained from using twitter by the establishment? Thinking out loud!

[Kartik]

It does look like his Twitter account is gone..I guess someone in the establishment wasn't happy with the fact that he was so open about things. I hope it's just that and not that he's retired from HAL.

[Kartik]

Found an interesting thing while reading a Typhoon interview on Hushkit. Was hoping to ask HVT about it, but not possible now.

Typhoon's AoA limit currently is a slightly more than 24 degrees. As it is for the F-16 apparently. Tejas Mk1's AoA is 24 deg with the FOC software. So the Tejas matches the Typhoon and F-16's AoA limit as of now.

But a new Aerodynamic Modification Kit (AMK) was developed for the Typhoon to allow it to increase the AoA to 34 degrees. They used a leading edge root extension and a strake to do that.



From the Hushkit interview:

Before I go back to the interview with Klax I feel I should explain a little background detail about the AMK. Typhoon’s supersonic agility is very impressive, but its current angle-of-attack (AoA) limits at lower speeds are less impressive; a Cassidian (Airbus Defence & Space) led effort demonstrated in 2014 would remedy this. The ‘Aerodynamic Mod Kit’ (AMK) includes re-shaped strakes, leading edge root extensions, and extended trailing edge flaperons. The AMK aims to deliver increases to the maximum wing lift, the AoA limit and the roll rates at High AoA. The strakes will generate vortices that will maintain a controlled airflow over the wing surface even at high angles of attack. When I spoke to EADS test pilot Chris Worning for an article in Aerospace he noted “The first stage was to proof the concept. Do some measurements to see if the strakes did what we thought they would do. And that went very well, the predictions were close. We will fly the Aerodynamic Modification Kit next. We have a mod kit and we’re hopefully going to fly it here this summer (at Manching). This is basically what you could put on a series production aeroplane.”

On the advantages he noted, “First of all they will give us a bit more angle of attack. The maximum angle of attack of the aeroplane increases, which is obviously helpful in close-in combat, if applied intelligently. The second thing they do is increase the manoeuvrability of the aircraft at high angles of attack. So at a given angle of attack, you have for instance, much higher roll rates: so the overall agility of the aircraft increases.”

The Typhoon’s current AoA limit is slightly more than twenty four degrees, approximately the same as an F-16. The new changes are expected to increase the limit to at least 34 degrees which will give pilots in combat a many more possibilities for nose-pointing.

I was wondering if ADA and NFTC could be looking at implementing something similar to improve the AoA limit on the Tejas Mk1 as well, with a similar strake and a LERX. We know that studies were carried out on the Tejas as well to add nose chine and fuselage strakes and they showed better aerodynamic characteristics. Lots of details in IR and JayS's excellent article below.

DDR- Tracking the Tejas part 1

IR, could you find out any more on whether these aerodynamic improvements may feature on the Mk1A and find their way back into the Mk1? We do know that the MWF design has a LERX like root extension and the wing tip mounted CCMs which actually showed better Cnβ and higher L/D ratio in the subsonic, transonic and supersonic regimes. Makes logical sense to see it being implemented on the Mk1A for sure.

[Karan M]

The HVT thing is shocking. I hope he's back.

[basant]

IAF has asked for 'improved' canopy wrt bird hit resistance (24mm thick instead of 16mm) and not for the more aerodynamically optimized one for Mk2 to be ported for Mk1A. Has that to do with significant changes to CLAW?

[Indranil]

Kartik,

Tejas doesn't need more AoA. More AoA will give you more ITR and lower speed handling. Tejas doesn't need help there.

They have studied strakes for NLCA Mk2. But it was not for increasing AoA. They want to delay uncommanded pitch up at transonic range to higher AoAs. A strake at a very similar position would have helped.

[JayS]

Kartik there is a paper published on Typhoon's AAMK - https://arc.aiaa.org/doi/abs/10.2514/1.C034473

It has roll issue at high AoA predominantly. The wings stall at lower AoA. The LERX helps stabilize the LE vortices at high AoA and side slip. LCA does not have problem with wing AoA, it goes on till 35deg or so without stalling. The issue is with directional stability, the rudder authority drops significantly post 25-26deg. Strakes might help in making the fin more effective, like it does in M2K. Other easy fix could be to increase the size of the fin and rudder to improve on the directional stability.

But as IR indicated, one needs to see what purpose this will serve and is if worth doing it..? If yes, it will be done in future, I am sure of it. LCA doesnt particularly need help in low speed handling as of now. Going lower than current level will need improvements elsewhere, like more powerful engines and TVC perhaps, because all controls lose effectiveness at too low speeds.

HVT pointed out an interesting thing the other day that the ITR may not be restricted by the G limit. STR always comes below the G-limit. Also, in some fighter's case, performance parameters like ITR and STR are not limited by AoA, but other limits too. The tightest turn again is typically at much lower G-turns than the max allowed. So we need to see in specific case of LCA whether increasing AoA limit gives a distinct advantage or not. Due to HMDS and high off-bore sight CCMs these days, pointing ability based solely on high AoA is not all that important. Also we should keep in mind that EFT2000 was optimised for high altitude supersonic flight. Any opponent worth his salt will never try to take of the Typhoon at very high altitudes as it has advantage up there (other than an F22 pilot perhaps). Not so much at lower altitudes and slower speeds. Hence its probably a more dire requirement for EFT 2000 to improve upon its low altitude low speed capabilities.

[srai]

LCA Mk.1

“ In-service aircraft are certified to fly from -3.5 to +8.0 Gs, up to an altitude of 50,000 feet, a top speed of Mach 1.6, and an angle of attack (AoA) of up to 24 degrees”

—> very respectable specs

“instantaneous turn rate (ITR) of near 30 degrees per second”
—> One of the best in class. Which fighters have more?

“a sustained turn rate (STR) of between 15 to 16 degrees per second.”

—> Decent enough. With HMDS & High-offbore sight CCM, one pass is enough. Don’t get into multi-pass turning fights.

“A minimum radius turn of 350 metres (m) radius was also exhibited”

—> Are there any other fighter with minimum smaller than this?

“ The ability to accelerate while in a climb is a virtue that only fighters with a thrust to weight ratio (TWR) of above 1.0 possess”

—> not underpowered as made out to be.

“ The FCS has now been updated to lower the minimum speed to 100 knots”

—> any other fighters lower than this?


I think these will be fully opened up at some point.
8.5 Gs
26 degrees AoA

[basant]

LCA Mk.1

“ In-service aircraft are certified to fly from -3.5 to +8.0 Gs, up to an altitude of 50,000 feet, a top speed of Mach 1.6, and an angle of attack (AoA) of up to 24 degrees”

—> very respectable specs

“instantaneous turn rate (ITR) of near 30 degrees per second”
—> One of the best in class. Which fighters have more?

“a sustained turn rate (STR) of between 15 to 16 degrees per second.”

—> Decent enough. With HMDS & High-offbore sight CCM, one pass is enough. Don’t get into multi-pass turning fights.

“A minimum radius turn of 350 metres (m) radius was also exhibited”

—> Are there any other fighter with minimum smaller than this?

“ The ability to accelerate while in a climb is a virtue that only fighters with a thrust to weight ratio (TWR) of above 1.0 possess”

—> not underpowered as made out to be.

“ The FCS has now been updated to lower the minimum speed to 100 knots”

—> any other fighters lower than this?


I think these will be fully opened up at some point.
8.5 Gs
26 degrees AoA

Thank you for the detailed explanation. I have a couple of doubts though:
1. We keep seeing reports that envelop has been tested successfully and will be gradually/fully opened in future. If the testing was thorough, why is this caution? If not, would it be premature conclusion based on testing perhaps the most complicated test points?

2. Several times on this forum (over a decade no less!) it was pointed out that JF-17 cannot even complete vertical loop. And IIRC, it was suggested that it could be due to FBW/CLAW. Why should that be so complicated? I mean, there are more difficult situations, like AoA limits, wake penatration, etc. I cannot see the reason for any challenge in completing a loop, unless it has to do with aerodynamics/air flow requirement for the engine itself (which I guess would be even less likely).

I would appreciate for sharing any thoughts on these.

[Indranil]

“ The FCS has now been updated to lower the minimum speed to 100 knots”

—> any other fighters lower than this?

It has been test flown to 106 knots. In service aircraft are software limited to 115 knots. Gripen is comparable. The Mirage 2000 can fly at 100 knots. Rafale and F-18 can fly slower (85-90 knots).

[Aarvee]

The HVT thing is shocking. I hope he's back.

What happened with the twitter account? Cant find any info.