ADA Tejas (LCA) News and Discussions

[kamaal]

You should have asked me for reference before you expose your limited knowledge with super confidence.

Here is a paper on Aerodynamic improvement of Tejas by CEMILAC team for performance improvement by aerodynamic improvements. This is not the only paper but there is an another paper published just 2 years back which says that drag in Tejas can be reduced by 8% which will result in 20% increase in transsonic improvement and 2% rise in highest speed. It will also facilitate 60 kg higher fuel.

https://drdo.gov.in/drdo/pub/dss/2009/main/2-CEMILAC.pdf

I am unable to locate that other paper but If i find it, I will certainly post it here for your reference. one of leading scientist of ADA has also said that they were going to focus on aerodynamic improvement then onward.

If you could please upload it, plz do it, because the one you shared is very older one and I have already read it before. Also the research in CEMILAC paper was done before the LSP stage started so actually all the improvements has already been incorporated in LSPs and transferred to production model.

But so far there is not a single document or research in public space or may be classified which could confirm the weight reduction of the order of 100-200 kg and aerodynamic improvement for MK1A, it is just not possible to bring this huge change and expect IAF kind of org to accept right away.

But if you have any doc, kindly share. MK1A for me is still FOC with AESA and EW suite.

 

[Prashant12]

The #Tejas is a tailless, Compound Delta #planform. This planform is designed to keep the Tejas small and lightweight. The use of this planform also minimises the control surfaces need (no tailplanes or fore planes, just a single vertical tailfin), permits carriage of a wider range of external stores, and confers better close-combat, high-speed, and high-alpha performance characteristics than conventional wing designs.

https://www.facebook.com/tejas.lca

 

[HariPrasad-1]

The #Tejas is a tailless, Compound Delta #planform. This planform is designed to keep the Tejas small and lightweight. The use of this planform also minimises the control surfaces need (no tailplanes or fore planes, just a single vertical tailfin), permits carriage of a wider range of external stores, and confers better close-combat, high-speed, and high-alpha performance characteristics than conventional wing designs.

https://www.facebook.com/tejas.lca

Others may be true except control surface. You have to increase the wing area to compensate the are of tails. Any design is a choice and compromise. You choose one and you loose the advantage offered by other design.

 

[scatterStorm]

Here is the conclusion of study of aerodynamic improvement of Tejas :

Conclusion
The supersonic wave drag characteristics of a generic fighter aircraft was studied initially based on its crosssectional area distribution. Preliminary Sears-Haack shapes and equivalent body of revolution geometries indicated significant scope in wave drag reduction. The canopy region was identified for shape modification to reduce drag and various geometries were studied in RANS solver CFD++ constrained by seat & safety system, structural and manufacturing requirements to arrive at the best canopy shape. The final modified canopy gave 6% reduction in
supersonic wave drag which translated to 20% improvement in transonic accelerations and 2% improvement in maximum level speeds. The pitching stability characteristics have improved in the modified fighter which results in less trim drag. The directional stability characteristics of the modified configuration has deteriorated resulting in lower cross over alpha which is proposed to be overcome by closed loop feedback control. This modified geometry also benefits with additional space in the aircraft behind the pilot that can be used to appropriately accommodate more internal fuel.

Thanks for posting the conclusion of the research paper. I gotta have hand on those RANS solvers with CFD++ constrains.

Now here's my observation, if the directional stability characteristics of the modified configuration as a corollary has deteriorated resulting in lower cross over alpha. That means in turbulence situation, Tejas has to increase it's speed substantially to over come the cross over speed, this would push the pilot in a situation where he cannot do anything to control the direction of the jet being headed, hence it would need a close loop feedback control to continuously make aware the pilot to increase it's alpha.

Also a question, that delta shaped airframe jet's bleed speed more on turning (Canards will fix this) but currently this anomaly being superimposed, result in bleed more energy and speed at higher alpha?

 

[HariPrasad-1]

I gotta have hand on those RANS solvers with CFD++ constrains.

Please elaborate this.

Rest of the part is a bit more complex for a layman like me to understand.

However , What I feel about tejas is that in an effort to make plane small, They increased the cross section or they reduced the length which resulted in a bit higher expansion of cross section with respect to length which resulted in poor area ruling which made aircraft a big more draggy in addition to other issues like canopy which is easier to solve but the drag because of sudden expansion in cross section is very difficult to solve and hence Mk2 was planned with an increase in length by 0.5m which again is a sub optimal design. Ideal length would have been 15m+ (As it was planed in Naval Mk2). However, that involved a lots of work as it is as good as making a new aircraft. So an inbetween solution was arrived at by increasing the length by 0.5m. If nosecone is also redesigned and made 0.5 m longer, that will give Tejas a lot better aerodynamic performance.

 

[scatterStorm]

Any design is a choice and compromise. You choose one and you loose the advantage offered by other design.

Yup pretty much, especially during prolonged merges with higher alpha (hopefully we won't see much WVR combat thanks to missiles), in fact canard delta configuration still cannot save from stall or post stall speeds during prolonged merges that why fighter pilots with single jet engine and especially delta winged configuration aren't allowed to take a tight high G maneuver at lower altitudes. I even refrain from saying "aren't allowed", rather I must write, "the pilots know that there jet has restrictions by design".

Take the case of an F15 against a single engine delta or delta canard config in WVR with no missiles on each party. In such case F15 would win without firing a single shot from it's cannon I leave the math for enthusiast.

unless, you are flying at higher altitude (still with good amount of atmosphere) to recover lost energy by performing a restrictive dive turn , in this case the gravity will provide enough energy and speed to counter stall or post stall situation in delta config providing enough lift. Or you have twin engines like the Eurofighter and Rafale. We gotta give it to those Europeans, they know there math.:biggrin2:

 

[scatterStorm]

Please elaborate this.

Rest of the part is a bit more complex for a layman like me to understand.

However , What I feel about tejas is that in an effort to make plane small, They increased the cross section or they reduced the length which resulted in a bit higher expansion of cross section with respect to length which resulted in poor area ruling which made aircraft a big more draggy in addition to other issues like canopy which is easier to solve but the drag because of sudden expansion in cross section is very difficult to solve and hence Mk2 was planned with an increase in length by 0.5m which again is a sub optimal design. Ideal length would have been 15m+ (As it was planed in Naval Mk2). However, that involved a lots of work as it is as good as making a new aircraft. So an inbetween solution was arrived at by increasing the length by 0.5m. If nosecone is also redesigned and made 0.5 m longer, that will give Tejas a lot better aerodynamic performance.

Sure, RANS is an acronym for "Reynolds-averaged Navier–Stokes equations", which I guess are used to calculate motion of an object and is a part of fluid dynamics subject. and CFD is just a way to computationally simulate the fluid flow. Hence Computational Fluid Dynamics or CFD.

We use RANS as a way to describe turbulence in the flow of fluid, by taking a timed average, but it can also be used to describe air turbulence, with slight modification to the equation.

A RANS solver is nothing but a piece of code/program in a pure "functional form", that is you simply create a function in your favorite computer programming language that just calculates RANS equations. I can create myself, but that's not the point.

In context to Tejas you posted a conclusion to the research paper you cited, which developed an anomaly of "lower cross over alpha", which gives substantial support to the hypothesis that changing the shaping of canopy by some x angle does affect it's cross over apha parameters. This means that in a high turbulence event, Tejas airframe might have to take a bit more stress! This would also put more stress to the pilot as well. This can affect the performance of the jet in such situations.

But what's interesting is that, the CFD constraints i.e. Since the canopy was reshaped a bit, the constraints of either having more space at the back of the pilot seat or not will affect the flight dynamics or not.

 

[scatterStorm]

Please elaborate this.

Rest of the part is a bit more complex for a layman like me to understand.

However , What I feel about tejas is that in an effort to make plane small, They increased the cross section or they reduced the length which resulted in a bit higher expansion of cross section with respect to length which resulted in poor area ruling which made aircraft a big more draggy in addition to other issues like canopy which is easier to solve but the drag because of sudden expansion in cross section is very difficult to solve and hence Mk2 was planned with an increase in length by 0.5m which again is a sub optimal design. Ideal length would have been 15m+ (As it was planed in Naval Mk2). However, that involved a lots of work as it is as good as making a new aircraft. So an inbetween solution was arrived at by increasing the length by 0.5m. If nosecone is also redesigned and made 0.5 m longer, that will give Tejas a lot better aerodynamic performance.

I think it's all about offering the jet at reduced cost, considering MK1 program was established to close the gaps and cover the learning curve in less time, so yes an increase in length means a completely new plane, hence it was decided to do it on MK2 variants.

We are learning to build war fighters on our own, this will have some compromises. What I am more looking forward is to see what they can do with AMCA after all the learning phase. This will be interesting thing to witness. Ahh some golden years for the aviation industry of our country.

 

[HariPrasad-1]

I think it's all about offering the jet at reduced cost, considering MK1 program was established to close the gaps and cover the learning curve in less time, so yes an increase in length means a completely new plane, hence it was decided to do it on MK2 variants.

We are learning to build war fighters on our own, this will have some compromises. What I am more looking forward is to see what they can do with AMCA after all the learning phase. This will be interesting thing to witness. Ahh some golden years for the aviation industry of our country.

I think the best way is also to hire some Russian scientist to work for us like Iranian does. Russians are masters of making the plane super maneuverable.

 

[Prashant12]

Up-Close with the #Tejas coming back in after a Sortie in Bangalore

https://www.facebook.com/tejas.lca

 

[Sancho]

I have heard that before but there is no official statement either from HAL or IAF. Plus a weight reduction of as small as 5-10 kg will require flight testing and approval from flying centres. Hence, there is no weight reduction in MK1A, it is simply FOC with AESA and EW suite, nothing new in it.

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Empty weight of LSP 8: 6735Kg

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HAL developing LCA-1P with AESA Radar
May 2015

...HAL Chairman and Managing Director (CMD) T Suvarna Raju told India Strategic in an interview that HAL shared the technology concerns of the user – IAF – as well as the urgency for production of the aircraft in view of the falling numbers of IAF combat squadrons due to obsolescence. The AESA and EW suite will make the new LCA variant more advanced than the supersonic MiG 21s in capability, even though it will be a subsonic aircraft compared to the ageing aircraft of the Soviet vintage...

...The aircraft will continue to have the same GE 404 engine however in this variant, but the lack of adequate power will be compensated by the warfare capability generated by the new sensors, with AESA providing a formidable force multiplication...

...The new LCA-MkI-P variant with the EW Package will also add some 50 kilos of more weight, but then, Mr Raju explained, the capability of the aircraft increases significantly, offsetting the disadvantage of a smaller engine.

The current LCA-MkI version uses 210 kilos with ballast in the nose to stabilize the aircraft. This will be removed, and the AESA and EW suite weighing about 250 kilos will be added. The net weight gain will be of about 50 kilos...

http://www.indiastrategic.in/topstories3767_HAL_developing_LCA-1P_with_AESA_Radar.htm

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HAL begins integration of mid-air-refueling probe on Tejas
March 12, 2016

March 12: Engineers and technicians at Hindustan Aeronautics Ltd’s (HAL) LCA-Tejas Division have begun the extremely complex integration of the aerial refueling probe on to the Tejas fighter.
During a visit to the HAL facilities, Mathrubhumi witnessed the fitment tests on the Limited Series Production-8 (LSP-8) variant of Tejas. The air-to-air probe, supplied by UK-based Cobham, is being fixed in front of the canopy and on the right side of the aircraft.
Similar to Mirage, Tejas too will have a fixed aerial refueling probe.
“The modification of LSP-8 is under progress. The structural modification for the attachment and load is under way. We also have to undertake fuel system and software modifications,” says V Sridharan, General Manager, LCA.

http://tarmak007.blogspot.de/2016/03/hal-begins-integration-of-mid-air.html?m=1

Apart of the refuelling probe, Cobham also added an new quartz nose, to replace ADAs older composite nose, but does it have the same weight?
Not to forget that we still wait for the final selection of AESA and EW, so it still might take time, till the final weight of MK1A is fixed, but either way, it's too heavy to deliver the required flight performance.

 

[Sancho]

Aerodynamic Improvements are already planned in MK1A.

Drag reductions were planned for MK2 and some might find it's way into MK1A, but the MK2 airframe will see several modifications, which changes the aerodynamics again, hopefully for the better.

 

[pruthvi24]

I'm posting a non technical stuff here I just met someone who was working on Tejas project there on a contract basis for some years .the person said there is lot of politics there for ex instead of selecting people based on merit they select people based on what language they speak for ex if there is a scientists from Andhra they will prefer people who only speak telegu and a tamilian prefers people who speak Tamil and stuff like that so the person left the Job since there was no hope on getting new contract renewed and is working somwherso else now says a lot why many of our projects are dead in the water the person was defence enthusiast was very happy during initial days now the person is very happy that he is out of there and is working in a job which is on a permanent basis

 

[ezsasa]

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Empty weight of LSP 8: 6735Kg

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http://www.indiastrategic.in/topstories3767_HAL_developing_LCA-1P_with_AESA_Radar.htm

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http://tarmak007.blogspot.de/2016/03/hal-begins-integration-of-mid-air.html?m=1

Apart of the refuelling probe, Cobham also added an new quartz nose, to replace ADAs older composite nose, but does it have the same weight?
Not to forget that we still wait for the final selection of AESA and EW, so it still might take time, till the final weight of MK1A is fixed, but either way, it's too heavy to deliver the required flight performance.

Not an expert...

even if Tejas mk1 has some flaws for now, it will have to be delivered to IAF. With out the monies from MK1 deliveries, MK2 cannot be funded.

 

[Sancho]

Not an expert...

even if Tejas mk1 has some flaws for now, it will have to be delivered to IAF. With out the monies from MK1 deliveries, MK2 cannot be funded.

GoI pays both, the procurement and the funding of upgrades and they are not based on each other.

 

[ezsasa]

GoI pays both, the procurement and the funding of upgrades and they are not based on each other.

PSU's do not run that way.. Their work culture may be similar to Govt, but their policies are similar to private sector.

IAF is the primary customer of HAL. Procurement process remains the same as any other vendor and customer relation ship. HAL has to show revenue and profits. most of their operational expenses are generated thru revenues.

But yes at the end of the fiscal they pay their dividends to Govt to get their next round of annual funds.
=======
Buyback of Shares & Payment of Dividend: HAL Makes Massive Contribution to the Nation
http://www.hal-india.com/Buyback of...es Massive Contribution to the Nation/ND__159

 

[HariPrasad-1]

Drag reductions were planned for MK2 and some might find it's way into MK1A, but the MK2 airframe will see several modifications, which changes the aerodynamics again, hopefully for the better.

True. One scientist had said last year that they were going to focus on Aerodynamics them onward. Many including saraswat and others had said that aerodynamic improvement has a scope in Mk1+ itself.

 

[HariPrasad-1]

=>

Empty weight of LSP 8: 6735Kg

=>

http://www.indiastrategic.in/topstories3767_HAL_developing_LCA-1P_with_AESA_Radar.htm

=>

http://tarmak007.blogspot.de/2016/03/hal-begins-integration-of-mid-air.html?m=1

Apart of the refuelling probe, Cobham also added an new quartz nose, to replace ADAs older composite nose, but does it have the same weight?
Not to forget that we still wait for the final selection of AESA and EW, so it still might take time, till the final weight of MK1A is fixed, but either way, it's too heavy to deliver the required flight performance.

If above table is true that it it is very disappointing. No weight reduction is seen from LSP1 to LSP8. it is very bad. We should have achieved atleast 6 tons by now.

 

[Prashant12]

https://www.facebook.com/tejas.lca

 

[Prashant12]

#Tejas SP-8 completes maiden flight successfully.