LCA TEJAS MK1 & MK1A: News and Discussion

Spitfire9

Regular Member
Joined
Jan 24, 2021
Messages
581
Likes
1,583
Country flag
No, it will be F404 only, whether Kaveri will be integrated in future depends on the dry version of Kaveri and success of 110KN JV engine
I don't see a reheat upgrade to a dry version of Kaveri appearing before a lot of (if not all of) the 83 Tejas ordered are delivered. Still, if Kaveri could reach performance required, 250+ engines could be produced as replacement engines for Tejas.

On the other hand, a derated 110kN engine makes more sense to me in terms of commonality, reliability.
 

Vamsi

Regular Member
Joined
Jun 27, 2020
Messages
371
Likes
1,779
Country flag
I don't see a reheat upgrade to a dry version of Kaveri appearing before a lot of (if not all of) the 83 Tejas ordered are delivered. Still, if Kaveri could reach performance required, 250+ engines could be produced as replacement engines for Tejas.

On the other hand, a derated 110kN engine makes more sense to me in terms of commonality, reliability.
Reheat upgrade depends only on success of Dry variant and 110KN engine.
 

Spitfire9

Regular Member
Joined
Jan 24, 2021
Messages
581
Likes
1,583
Country flag
Impossible. How will you feed it with increased airflow (85-90 kg/s) required for delivering 110-120kN from the same inlets designed for F404 (70 kg/s)? The best bet for re-engining Mk1/A is certifying the Kaveri with Safran (dry variant is already slated for testing around 2022-23) including reheat section. Second, best is to use M88-2 (Rafale also flew with F404 initially so both engines should be somewhat interchangeable) by adding some redundancy in controls for single-engined fighters. Latter option seems likely only if MWF fails to stick to its time line- and India goes for a larger order (100+) of Rafale and gets to assemble M88-2s locally.

Mk2 has bigger intakes, so can accommodate the 110kN engine. The India-UK agreement said as much.
About intakes, on another site I said I thought an engine with more thrust than F404 would inevitably mean that inlet modification was needed. It was pointed out to me

Not necessarily. The velocity of the air would simply increase. You'd get slightly higher intake losses, though, if the intake isn't well adapted to the engine.

For example, the A321 comes with up to 137 kN per CFM56 engine and the A318 only comes with 96 kN. Yet they still use the same nacelle and inlet.
and
F-15 inlet example. Started out with a 23,840 lbs thrust engine and is now using a 29,400 lb thrust engine, and its capable of using the 32,500 lb thrust F-110-132 as well. All with the same inlet.
So if the Tejas inlet is similar...
 

Rajaraja Chola

Regular Member
Joined
Mar 25, 2016
Messages
442
Likes
1,161
Country flag
When the resources are limited then using them on things like Ejection Seat is waste of resources.
There are many other things which needs urgent attention.
By the way we are also using british radome for tejas . Right ?
This is how slowly and steadily indigenisation is increased. Whether we will use it or not we would like to have a product when shit hits the fan. The problem is DRDO had developed so many products which you can call advanced or which IA had never required at that time, but later was forgotten or inducted through foreign sales. Not huge ones, but small projects.
Radome, Radar is already being tested, it's good to see development on ejection seats. Going forward we have to try to indigenise everything possible except the engine.
 

Roland55

Regular Member
Joined
Jun 8, 2020
Messages
82
Likes
309
Country flag
This is how slowly and steadily indigenisation is increased. Whether we will use it or not we would like to have a product when shit hits the fan. The problem is DRDO had developed so many products which you can call advanced or which IA had never required at that time, but later was forgotten or inducted through foreign sales. Not huge ones, but small projects.
Radome, Radar is already being tested, it's good to see development on ejection seats. Going forward we have to try to indigenise everything possible except the engine.
you guys are already are getting towards the majority of Nationalized components, that quite a remarkable accomplishment!
 

MonaLazy

Regular Member
Joined
Aug 12, 2019
Messages
444
Likes
2,499
Not necessarily. The velocity of the air would simply increase. You'd get slightly higher intake losses, though, if the intake isn't well adapted to the engine.
Same inlet may work for A318/A319/A320/A321 because of atleast two reasons.

1. They belong to the same CFM56-5B family of engines. Specs pulled from the manufacturer:
1624726972248.png


wiki gyaan:

The CFM56 is a high-bypass turbofan engine (most of the air accelerated by the fan bypasses the core of the engine and is exhausted out of the fan case) with several variants having bypass ratios ranging from 5:1 to 6:1, generating 18,500 to 34,000 lbf (80 kN to 150 kN) of thrust. The variants share a common design, but the details differ.
2. Subsonic inlets are simple- straight & short, won't vary much from one engine type to another. Leaning on jet engine inlet info from NASA

1624728397542.png


The inlet does no work on the flow, inlet performance has a strong influence on engine net thrust. As shown in the figures above, inlets come in a variety of shapes and sizes with the specifics usually dictated by the speed of the aircraft.

SUBSONIC INLETS
A simple, straight, short inlet works quite well. On a typical subsonic inlet, the surface of the inlet from outside to inside is a continuous smooth curve with some thickness from inside to outside. The most upstream portion of the inlet is called the highlight, or the inlet lip. A subsonic aircraft has an inlet with a relatively thick lip.

SUPERSONIC INLETS

An inlet for a supersonic aircraft, on the other hand, has a relatively sharp lip. The inlet lip is sharpened to minimize the performance losses from shock waves that occur during supersonic flight. For a supersonic aircraft, the inlet must slow the flow down to subsonic speeds before the air reaches the compressor. Some supersonic inlets, like the one at the upper right, use a central cone to shock the flow down to subsonic speeds (reminds of the M2K inlet). Other inlets, like the one shown at the lower left, use flat hinged plates to generate the compression shocks, with the resulting inlet geometry having a rectangular cross section (reminds of F-15/Su-30 inlets). This variable geometry inlet is used on the F-14 and F-15 fighter aircraft. More exotic inlet shapes are used on some aircraft for a variety of reasons. The inlets of the Mach 3+ SR-71 aircraft are specially designed to allow cruising flight at high speed. The inlets of the SR-71 actually produce thrust during flight.

On how the F-15 can go from 106kN all the way to 144kN- a power bump of 36% all with the same inlet, let's just say it is over-engineered and incredibly complex compared to the simple pitot intake on LCA.

F-15
has a 3 part vari-ramp, a Diffuser Ramp and a Bypass door. It automatically changes the inlet angle (orientation) from forward to down and throat height of the intake by pivoting the 1st ramp and adjusting the 2nd and 3rd ramps as needed depending on AOA and airspeed. It makes continuous changes as needed in flight.



F15 inlet in action-




LCA
1624730124976.png

This was in response to someone asking why Tejas is limited to 1.6 Mach.


Finally, see the evolution of Hornet to Super Hornet and Gripen C to Gripen-E- both have been redesigned with bigger inlets to accommodate additional airflow as both make the same jump from F404 to F14 engines the Tejas program will now attempt with MWF-





1624730944851.png
 

onlinpunit

Tihar Jail
Banned
Joined
May 1, 2021
Messages
163
Likes
297
Country flag
That too will be replaced.

And please list the developmental projects that are languishing due to fund shortage?
Ok.. now if the rumors are correct there will be a joint indo british engine for MK2 ! Beat that. !
 

ladder

Senior Member
Joined
Mar 28, 2013
Messages
6,829
Likes
9,862
Country flag
Ok.. now if the rumors are correct there will be a joint indo british engine for MK2 ! Beat that. !
Mk2 as is built around F414, it will be easier to fall back to F414 in case if any problem. The export model can still be equipped with F414 if the requirement is as such.
 

MonaLazy

Regular Member
Joined
Aug 12, 2019
Messages
444
Likes
2,499
India should evaluate the French option here too , safran m88.
MoD is already past that bridge. Evaluated both M88 core + Kaveri and full replacement with M88.


Didn't work out because of cost demanded by Safran. The irony is India will now assemble M88 only if MWF slips on its schedule and we go for 100+ Rafales. The French offered screwdrivergiri of the engines (we call it ToT) if we order more than hundred.
 

Spitfire9

Regular Member
Joined
Jan 24, 2021
Messages
581
Likes
1,583
Country flag
Mk2 as is built around F414, it will be easier to fall back to F414 in case if any problem. The export model can still be equipped with F414 if the requirement is as such.
Good point about F414 for export customers who want it.

To me it would be a good idea to design a 110kN engine with dimensions allowing it to be fitted in MWF. Technological advances since F404 was designed should allow that, shouldn't they?
 

LaIllahaSigmar

Regular Member
Joined
Jun 20, 2021
Messages
507
Likes
2,857
Country flag
On the topid of potential customers for Tejas, are Ireland and Japan possible candidates?


Ireland:

Lacks any modern jet aircraft.

Only has 8 turboprop aircraft.
Deoneds on UK for airspace security.

Is currently looking for a interceptor aircraft.

Will probably choose a cheap and easy to maintain fighter.

Can Tejas full fill this requirement?


Japan:

As you may be aware, Japan is regularly poked by China.

Japan has to scramble it's F-15s regularly to intercept them.

Some analysts have suggested that China's game plan here is to wear out the japanese planes and impose costs on them.


Japan is not currently looking for a light interceptor but should it do so, would Tejas, relatively easy to maintain with good availability (?) be a fit for this role?
or would the range required limit its use?
 

MirageBlue

Regular Member
Joined
Mar 19, 2020
Messages
165
Likes
889
Country flag
You say the randome will be replaced. Good to hear. How soon? If your answer is many years, I think you have answered your own question.
There is a new DRDO project to develop a quartz radome on the Tejas Mk2 MWF program. But, for the initial prototypes, DRDO has gone back to Cobham to get them to work on a new quartz radome, since the Mk1 and Mk1A radome is slightly larger than the Mk2 radome.
 

MirageBlue

Regular Member
Joined
Mar 19, 2020
Messages
165
Likes
889
Country flag
One was in testing ,photos were there on a thread here , lighting test if i remember
The lightning test was for the older Kevlar radome that was developed in India, and used on the Tejas Mk1 prototypes. However, it saw higher than acceptable EM losses and then had to be replaced by the quartz radome from Cobham. The new quartz one is apparently in development (as per the MWF Project Director) but will take time to be ready for service.
 

Latest Replies

Global Defence

New threads

Articles

Top