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

[Indranil]

I agree too. It is a show of confidence. It makes the rounds in the halls of governance, halls of IAF, halls of dalals and halls of DDM.

[Indranil]

Kartik,

No trainers with the squadrons. They borrow from ADA whenever required.

[SidSoma]

Any news on when SP-8 is going to be out

[Kartik]

Kartik,

No trainers with the squadrons. They borrow from ADA whenever required.

Thanks for clarifying IR.

I did have another question- will the Tejas Mk1A prototypes be modified LSP prototypes? Would make more sense than dedicating resources and using up production and assembly slots on the existing Mk1 assembly line.

BTW, has anyone any idea what happened to the prototype that was supposed to be modified to be the testbed for the EW suite?

[Indranil]

I had initially heard that Mk1A prototypes will be modified LSPs to save time. But I don't see that happening. If they are going to change the layout inside the fuselage and make structures lighter, I can't see how modifying an LSP will be easier.

[Gagan]

The joyride is an endorsement all right
It takes a leap of faith to put a serving chief of a military to fly a single engined aircraft
There are rules for this sort of thing - people above a certain classification can only fly aboard a twin engined aircraft

Remember Pres R Venkatraman ji getting sea sick on a cruise, and there being only a chetak available on the Navy Ship. The presidents bodyguards threw the rulebook at the Navy walas about there being only a single engine on the chetak, and the President no can fly on this bird for medical evac, even if his excellency is sick

[SaiK]

#Tejas has finest handling capability making it a state-of-the-art system providing stability under extreme\unstable conditions. #Tejas has got rules based Artificial Intelligence in its FCS. Continuous R&D is on in AI to enhance #Tejas' capabilities: @DRDO_India head Christopher https://t.co/MJ33uVF9KY

[tsarkar]

I had initially heard that Mk1A prototypes will be modified LSPs to save time. But I don't see that happening. If they are going to change the layout inside the fuselage and make structures lighter, I can't see how modifying an LSP will be easier.

Mk1A will have -
1. Systems Upgrade like Radar & Jammers
2. Making Structures production friendlier with ease of access and potential weight loss.

For 1 - LSPs & PVs can be used - preferably the ones wired for Radar & Jammers
For 2 - yes, its not easy to use LSPs, but no other way to test modified structures, unless 3 of the 83 Mk1A are PV/LSP vehicles.

[vasu raya]

#Tejas has finest handling capability making it a state-of-the-art system providing stability under extreme\unstable conditions. #Tejas has got rules based Artificial Intelligence in its FCS. Continuous R&D is on in AI to enhance #Tejas' capabilities: @DRDO_India head Christopher https://t.co/MJ33uVF9KY

Seems like they have a route to unmanned flights more automation, would be great if they can take advantage of the growing fleet.

[SaiK]

Expert systems are rudimentary AI. Just saying.

[schinnas]

Rules based AI implies rudimentary AI.

[Indranil]

I agree. And this IS my field. So, I can speak with some authority

All AI is rule based. We havn't designed machines yet which can really think and find out something new out of nowhere. Most state-of-art AI are classification algorithms. AI systems such as those used by Alpha Go "learn" new rules, from existing rules by exploring new "space" with another set of rules.

What Christopher sir is calling "rule-based" is not AI, or at best, very rudimentary AI. Under that definition, all computer programs are AI.

[vasu raya]

Its just software, they can load ANN based control systems that are initially run in shadow mode. Problem is its like voodoo science as far as flight certification for manned systems goes.

For example, the RTOS that HAL developed was actually model checked, it gives confidence in the system. ANNs are more empirical in nature so one good metric of confidence in it can be faults measured per thousand flight hours. They get better with large datasets which is where fleet numbers can make a difference. Automating already explored space is probably easier.

Here is a problem, not sure if it is related to increasing AoA, which would be about exploring new space.
https://www.thehindubusinessline.com/ne ... 794759.ece

In addition, Tejas has rules-based Artificial Intelligence incorporated into its Flight Control System (FCS), he said at the third International Federation of Automatic Control (IFAC), International Conference on Advances in Control & Optimisation of Dynamical Systems (ACODS 2018) here. The FCS provides the pilot 'carefree handling'. However, flight limits cannot be exceeded, which at lower speeds on aircraft such as the MiG-23/27 or Jaguar, results in the loss of the aircraft. The Aeronautical Development Establishment, Bengaluru, and HAL have been involved in the development of Tejas.

However, it has posed challenges for pilots in controlling its longitudinally unstable airframe, which escalates rapidly any disturbance of even a small magnitude. A major challenge that has resulted in delays and long gestation for the Tejas development programme.

[SaiK]

You don't need flight certification for model checking. Both are mandatory for any RT system, and the former being mandatory for any system to get operational clearance. Model checking ain't voodoo science, if that is what are trying to say.

[Indranil]

I think he is referring to the limited interpretability of NN-based decisions. You will have a very difficult time convincing a certifying agency that my artificially stabilized aircraft makes decisions based on empirical evidence. I can tell you "why" a decision was made, but not "how" that decision was made.

[NachiketM]

However, it has posed challenges for pilots in controlling its longitudinally unstable airframe, which escalates rapidly any disturbance of even a small magnitude. A major challenge that has resulted in delays and long gestation for the Tejas development programme.

I certainly hope that this challenge has been mitigated as the tense of the statement suggests that this problem is present and inheritent (which it should be on account of the airframe).

Is there any chance that this might be an issue in opening the AoA envelope further? The last I heard about the AoA of the Tejas was opened to 26 degs for the Bahrain Airshow ... Does anybody know if the N0. 45 squadron Tejas is flying with 24 degs or 26 degs at the moment?

Can it goto 28 degs ?

[Indranil]

The reporter is confused.

The FCS controls all the variability. The pilot has to be cognizant of flight envelop and plan accordingly, but he does not have to worry about exceeding limits. This is not the case with Jaguars, Mig-27 etc., where he has to do both. The latter is quite difficult on high-performance aircraft and most of the pilot's time is spent in the latter. The mission becomes second priority. Not the case with modern aircraft like Tejas.

The fighter has been operationally cleared for 24 degrees and the trainer to 26 degrees. AoA in isolation doesn't mean anything. The ITR is fabulous and so is slow speed handling. Both are world-class. You have already seen it fly at 120 knots. They are currently fine-tuning the auto recovery software. During flight testing they found they can recover from significantly lower speeds. Let me leave it at.

[ramana]

I am wondering if the Mk1A should be armed with the DEFA 30mm cannon instead of the 23mm Gsh.

Reason why is the cannon round 30x113 is more effective and is made by OFB.
It has higher muzzle velocity and fires a heavier charge. The rate of fire is pretty good at 1800/1200 rpm.


http://www.ofb.gov.in/products/data/amm ... den_he.htm

Gsh is lighter cartridge, lower muzzle velocity but higher rate of fire due to twin barrels.

DEFA is longer by 0.6 m and heavier at 85 kg vs 50 kg for GSh.


And the same cannon will arm the Rafale and the M2K.

So lots of commonality.
Maybe Rafale offset should have DEFA as MII.
Can arm the Tejas and replacement/spares for the Rafale.

Did IAF get rid of all the DEFA guns from Toofani onwards?

[Neela]

From someone who has a view of HAL Airport runway.
He swears Tejas can take off in 300m.
From this point12.949036, 77.656653 (google maps) with thick double bars as starting point , the Tejas takes off regularly just after the second smaller double bars.

[tsarkar]

I am wondering if the Mk1A should be armed with the DEFA 30mm cannon instead of the 23mm Gsh.

The lower weight of gun and ammunition + greater number of rounds is the reason GSh-23 was selected. GSh-23 and ammo is manufactured at OFB since the days of MiG-21 manufacture. Even Chinese chose GSh-23 for JF-17. I believe this spec came from MiG-21 days in the original ASR. This is not a very critical requirement - a change would further delay the program.

30mm guns were used in Hunters, Sea Harrier under fuselage Pods, Jaguar & Mirage 2000. Aden and DEFA are respective derivatives of WW2 German cannon.

[JayS]

From someone who has a view of HAL Airport runway.
He swears Tejas can take off in 300m.
From this point12.949036, 77.656653 (google maps) with thick double bars as starting point , the Tejas takes off regularly just after the second smaller double bars.

For what config...??

[Neela]

From someone who has a view of HAL Airport runway.
He swears Tejas can take off in 300m.
From this point12.949036, 77.656653 (google maps) with thick double bars as starting point , the Tejas takes off regularly just after the second smaller double bars.

For what config...??

He is too far away to see config.

[Viv S]

From someone who has a view of HAL Airport runway.
He swears Tejas can take off in 300m.

There are markers every 100 metres I think.

[srai]

^^^
Takes off before 3 markers

[JayS]

From someone who has a view of HAL Airport runway.
He swears Tejas can take off in 300m.

There are markers every 100 metres I think.

Every 500ft, not being too pedantic.

[Viv S]

Every 500ft, not being too pedantic.

Rough eyeball - should be about 1000 ft to lift off I think. The third marker is in the picture at rotation but the aircraft is considerable distance behind it.

[NachiketM]

From someone who has a view of HAL Airport runway.
He swears Tejas can take off in 300m.
From this point12.949036, 77.656653 (google maps) with thick double bars as starting point , the Tejas takes off regularly just after the second smaller double bars.

The thick double bars are aiming point markers... thats where the pilots aim for landing the a/c... The grey area at the extremities of the runway 09-27 is the threshold area where you can taxi or start the take-off run but its not strong enough to land ... every marker denotes a distance of 500 mts ... so from the google image you provided the distance from the start of the threshold area to the pin you placed is approximately 900 mts to a 1000 mts which is also great for short takeoff... Do consider that with clean configuration Tejas pilots might not be employing abterburner which if employed will make the take-off run further shorter...
A little off topic but interesting ... I spotted 2 jaguars, 3 Mig-21s, and a Mig-27 on the HAL apron/parking along with a few Helos and transports ... Also on the adjoining smaller apron to the left an aircraft looking like Saras ... i may be wrong about the Saras ...But quite a collection there for HAL ...

[nachiket]

The thick double bars are aiming point markers... thats where the pilots aim for landing the a/c... The grey area at the extremities of the runway 09-27 is the threshold area where you can taxi or start the take-off run but its not strong enough to land ... every marker denotes a distance of 500 mts ... so from the google image you provided the distance from the start of the threshold area to the pin you placed is approximately 900 mts to a 1000 mts which is also great for short takeoff... Do consider that with clean configuration Tejas pilots might not be employing abterburner which if employed will make the take-off run further shorter...

500 ft not m. Aiming point is usually 1000ft from the threshold except in cases where aircraft have to come in higher and land further down the runway due to terrain limitations in approach path. But you're right that takeoff roll will begin near threshold marking not the aiming point marking. So if the Tejas can really take off before the smaller marker after aiming point that comes to less than 1500ft (~450m) which is excellent. Minimum takeoff distance for a Mirage 2000 is 1650 ft IIRC, with 2 CCMs at sea level.

[Rakesh]

https://twitter.com/sjha1618/status/966341699856490496 ---> Based on my discussions with people over there, I see HAL being able to produce 12 Tejas SPs in the next fiscal year itself. While HAL receives a lot of criticism, it cannot be forgotten that they are the only ones in India who actually build aircraft & do so with staccato orders.

https://twitter.com/sjha1618/status/966342474519273472 ---> Some major private entities in India simply want to be license producers of shiny foreign toys. Some others are already producing indigenous designs. The divide is clear & depends to a great extent on the background and cultural outlook of the top executives in any firm.

[SBajwa]

So I guess the FCS is making decisions like

IF speed > 500 kmph AND altitude < 200 feet
Then sound Alarm/bombs_cannot_be_dropped/etc

IF flying_upside_down AND altitude < 100 feet
Then reverse flying_stick automatically

[Kartik]

Saurav Jha's article on the Tejas, the need for Mk1A and the final logical conclusion to the Tejas program, the Tejas Mk2; also mentions the possibility of canards on the Mk2.

I personally fully agree with all his points.

link to article

Indian airpower: go big on Tejas, or go home
By Saurav Jha Jan 1 2018, 23:08 IST

The Indian Air Force's decision to issue a request for proposal (RFP) to Hindustan Aeronautics Limited (HAL) for the procurement of 83 Tejas MK-1A light combat aircraft (LCA) bodes well for the cause of military-industrial indigenisation in India. And since this RFP has been issued at a time when HAL is putting in place the means to double annual production rates for the Tejas, it shows that the Ministry of Defence (MoD) is hopeful that the homegrown fighter will contribute towards shoring up IAF's squadron strength in a major way.

Indeed, the significant investment made into setting up a second advanced manufacturing line for the Tejas by HAL would be wasted if the intention were to truncate production at just the numbers projected till now, which as of date is some 123 units once we take into account the recent RFP. Instead, the focus needs to be on taking the Tejas programme to its logical conclusion, which would be the development and production of a more capable MK-2 variant in sizeable numbers.

Such a move would not only serve the purpose of obsolescence management and traditional product improvement, it would consolidate the gains made in terms of creating an aeronautical base in India via the LCA programme and provide the industrial pre-adaptation necessary for credibly producing a homegrown fifth-generation fighter. Meanwhile, it is imperative that various imported sub-systems used in Tejas variants be indigenised as soon as possible to both reduce operational risk as well as increase the domestic value capture of the programme.

The MK-1A variant of the Tejas is a step up from the baseline MK-1 (of which a total of 40 are on order) in terms of its avionics fit, maintainability and the fact that it will have in-flight refuelling capability. However, both the active electronically scanned array (AESA) radar and the self-protection suite that the MK-1A will sport are expected to be of imported origin.

HAL has floated tenders to procure the same from international vendors. HAL also intends to license-produce these sub-systems at its Avionics Division in Hyderabad and will also assume the responsibility to maintain, repair and overhaul (MRO) them. The company has decided to do so because indigenous alternatives to these items, such as the Defence Research and Development Organisation's 'Uttam' AESA radar and unified electronic warfare suite (UEWS) are both still under development.

Clearly, HAL wishes to reduce the risk to the overall Tejas build programme by first firming up supplies from abroad and then undertaking license-production of the same, while creating another value stream for itself in the process. It is well understood that the total orders that HAL may end up receiving over the course of the Tejas programme is contingent upon its ability to deliver this combat aircraft on schedule. At the moment, due to a firm order of only 40 of these fighters, HAL has taken its time in executing the same, with only five serial production jets having been delivered to the IAF's 45th Squadron as on date.

However, with serious movement on the MK-1A front, HAL knows that it will now have to demonstrate the ability to build up to 16 Tejas fighters a year. For this, HAL is currently scurrying to get its component and sub-assembly supply chain in place. Now, as far as the imported AESA radar for the MK-1A is concerned, a certain amount of engineering work will have to be done to fit it inside the nose of the plane, since its dimensions are the same as the MK-1.

Mk-2, the real deal

Due to the fact that the MK-1A will essentially have the same aero-body as the MK-1, it will not really be compliant with all the aerodynamic performance parameters desired by IAF in its air staff qualitative requirement (ASQR) for the Tejas design. It is only with the MK-2 variant that the developers of the Tejas, DRDO's Aeronautical Development Agency (ADA), expect near-total compliance with the IAF's requirement. But for this, the addition of a pair of canards and an engine of higher thrust capability than the current Tejas engine will be necessary, according to one top former DRDO official.

Now, it must be said that the addition of canards is something that the 'control law' of the Tejas can be readily modified to accommodate, given that it was developed indigenously and something that ADA designers are well versed in.

A revamped Tejas Mk-2 will also have modernised line replacement units and a number of other features, which together with the improved aerodynamic performance will make it one of the better fourth-generation 'plus' fighters out there. Moreover, a long production run of the Mk-2 will also provide the industrial pedigree necessary, without attrition of imbibed skills, to produce the Advanced Medium Combat Aircraft (AMCA) when that programme reaches fruition.

Meanwhile, it is important that India uses the growing scale of the Tejas programme to put in place joint ventures with foreign majors to secure the 'last mile' problem resolution support required to productionise key sub-systems such as the AESA radar to reduce both sanction and life-cycle cost risks for the Tejas, while increasing the share of domestic valued added to it. Interestingly, such collaborations are now forthcoming and even being explored as part of offset discharge for other military imports. Of course, the most key sub-system of all that needs to be indigenised would be the low-bypass turbofan engine powering the Tejas.

Once again, India needs to strike a credible deal to mature its own domestic Kaveri engine programme, even as the option of license-producing the current and future GE engine variants powering the Tejas family can be pursued by HAL's engine division in partnership with domestic private players. Simply put, Indian airpower has to either go big on the Tejas programme or go home.

[mappunni]

So I guess the FCS is making decisions like

IF speed > 500 kmph AND altitude < 200 feet
Then sound Alarm/bombs_cannot_be_dropped/etc

IF flying_upside_down AND altitude < 100 feet
Then reverse flying_stick automatically

Might be easier for quadcopters and other remotely piloted crafts. There are open source software available for it.

http://cleanflight.com/

[SaiK]

We never heard earlier (from any top DRDO official on oped) the canards were must to satisfy ASQR specs.

[Indranil]

It is not a must. But having atleast one pair of tail planes helps. Mk2 will have canards.

[nachiket]

It is not a must. But having atleast one pair of tail planes helps. Mk2 will have canards.

Is this confirmed?

[Indranil]

Not officially. But it has leaked out enough number of times now and in enough number of places for for me to speak about it.

[nachiket]

We haven't seen even a scale model of a Mk2 design with canards. This decision will increase time taken for development and testing. I'm wondering if this is a case of best being the enemy of good enough.

[ramana]

The Grippen has them no? So Mk2 will have them to satisfy imported look.

[Rakesh]

^^^ Good one Ramana-ji!

Do we know who the pilot of SP-5 was on her first flight on Feb 02nd?

[Vivek K]

It is not a must. But having atleast one pair of tail planes helps. Mk2 will have canards.

So the MK2 will come, with canards!