LCA: News & Discussions: 15 August 2017

ramana · Post by **ramana** » 26 Dec 2017 06:14

'Design your own fighter realm' folks.

Dileep · Post by **Dileep** » 26 Dec 2017 07:09

Let me try some 'shaivite' piskology (ie following lord Shiv

)

We had always been a 'buy' country, not a 'make' country, ever since the celtic barbarians overpowered us. We are used to get things in finished state, so that we miss the whole cycle of development. This is true with pretty much everything here. We do not appreciate the time, effort, money and pain involved in developing something. We are like this onlee.

The forces were no different. They were used to get stuff that are developed to a great extent, if not fully developed. The antagonism against Tejas comes mostly from this inexperience.

NOW.. with Tejas, at least a part of IAF is getting converted. The pilots experience the awe of contributing ideas, getting them implemented, and getting to verify them by actually flying. The airmen experience the awe of making suggestions that make their life easier, and seeing it implemented. The sense of 'ownership' is percolating within.

That is why we saw an immediate 'appropriate response' from within the force itself about the mudslinging attack recently.

Let me make a bold prediction here. The snowball started rolling.. no one can stop it.

ramana · Post by **ramana** » 26 Dec 2017 07:21

Dileep, on that note Merry Christmas and Happy New Year!!!

ArjunPandit · Post by **ArjunPandit** » 26 Dec 2017 10:12

I was looking at the effect of canards on twin delta and came across this wiki site
https://en.wikipedia.org/wiki/Canard_(aeronautics)
https://www.pprune.org/military-aviatio ... nal-2.html

Two key things

Conventional delta wings can struggle with control saturation at high incidence. The flaperons run out of authority in pitch and roll. Canards enable the flaperons to operate around their mid position so you don't run out of control authority at the extremes. They also help with trimming across the Mach range. Foreplane/deltas can also achieve performance targets with lower overall masses

having canards enabled far better maneuverability than a pure delta, and that as the foreplanes produce a lifting force rather than a downforce (as with a conventional tail); then you could get away with a smaller wing and still have good turning performance.

IAF's darling aircrafts(no sarcasm/pun intended) Rafale/Gripen have canards. I hope it is the case of Sneha ullal(MK2) for Ash(Gripe-n0)

Rakesh · Post by **Rakesh** » 26 Dec 2017 10:30

IR and Dileep, you gave this jingo hope wrt to Mk2. Thank you to you both!

Philip · Post by **Philip** » 26 Dec 2017 11:30

So will MK-2 resemble the Gripen?

ashishvikas · Post by **ashishvikas** » 26 Dec 2017 11:50

JayS wrote:
Indranil wrote:Can we move the discussion to re-engining LCA with anything other than the F414 to the design your own jet dhaga.
I think we should also move related posts from last couple of pages to Design your own Fighter thread.

Interestingly while replying to one post on 0.5mtr plug a couple of days ago here, I typed that I would rather have ADA go with 1mtr plug a la NLCA. I first thought of 0.5m each before and after the wing, but that would have moved engine back and wouldn't have helped area curve in rear portion either. So I thought better go with 1mtr plug ahead of wing itself. But then that would reduce static instability margin. So I thought it would be perhaps possible only if canards can be put on. Which seemed highly unlikely a couple of days ago. So I deleted that part of my post thinking its just a jingo dream. But now with the revelation that Canards can be put on LCA Mk2, I would definitely want ADA to go with 1mtr plug or even more if possible and maximize internal volume, the more the better, use all for fuel. There is quite a bit of scope for plug from wave drag perspective and canards will help maintain static instability margin as well as reduce trim drag. Adding half mtr plug would give significant boost to internal fuel if all of it can be used for fuel. I estimate a good 1000-1200ltr Volume availability from this.

JayS Sir, NLCA was planned for 1 meter plug without canards. CD Balaji has been mentioning this to NDTV interview in this video at 3:15. 1 meter plug will give space for 7--kg of fuel along with lighter landing gear.

So, just wanted to understand how different is NLCA with MK2 ?

https://www.youtube.com/watch?v=pzSM3ohvQqE

SaiK · Post by **SaiK** » 26 Dec 2017 12:09

The Tejas Mk-1A will carry an Israeli Elta 2052 AESA radar, podded Electronic Warfare (EW) suite and Cobham in-flight refuelling probe. New air-to-air missiles and precision munitions are also being considered by ADA, in addition to the R-73 and Rafael Derby BVRAAM, already integrated on Tejas Mk-1 aircraft.

that is a pretty strong statement we can't ignore

Aditya_V · Post by **Aditya_V** » 26 Dec 2017 12:19

SaiK Link to your quote?

SaiK · Post by **SaiK** » 26 Dec 2017 12:23

Sorry, I thought it was linked here earlier

https://www.flightglobal.com/news/artic ... rs-444456/

suryag · Post by **suryag** » 26 Dec 2017 14:54

Not that it matters but following quote(from an already posted link) mentions the turnaround time roughly.

http://english.mathrubhumi.com/news/ind ... -1.1700394

He said during the outstation detachment at AFS Thanjavur recently, SP-1 and SP-2 flew seven sorties in a single day.......

ashishvikas · Post by **ashishvikas** » 26 Dec 2017 16:09

SaiK wrote:Sorry, I thought it was linked here earlier

https://www.flightglobal.com/news/artic ... rs-444456/

Sorry Sir, this news doesn't look genuine.

deejay · Post by **deejay** » 26 Dec 2017 16:30

Actually, flightglobal is amazingly sharp in details. Very few articles quote numbers and very few bother to cover the history / geography. I may not like the narrative or some numbers may be here / there but Mike Rajkumar is an interesting fellow to watch out for. Narrative yahan bhi set ho raaha hai. Hints are available in the mention of F16, Gripen and Tejas Mk 2.

His take on IAF sqn nos are also interesting.

A recently released parliamentary report on India’s defence forces, states that the air force is now down to 33 active fighter squadrons as against the authorised strength of 42.

Alarmingly, the report quotes an air force reply, stating, “14 squadrons of MiG 21, 27 & 29 are due for de-induction in next 10 years, the present level of 33 squadrons will further go down to 19 by 2027, and may further reduce to 16 by 2032.”

Two things here - Mig 29 sqns - are we expecting Mig 29s to retire and also the number down to 19 from 33 (33-14=19) assumes no fresh inductions. These also exclude induction of already contracted Tejas and Rafale. So yes, numbers are representing worst case scenarios. Secondly, which Parliamentary report is this?

tsarkar · Post by **tsarkar** » 26 Dec 2017 17:55

^^ The report is very unconvincing. It misses 20 FOC orders. It also mentions Elta 2052 radar when the radar RFP winner is yet to be announced and Thales et al coming up with their own AESA radar proposal for Tejas.

tsarkar · Post by **tsarkar** » 26 Dec 2017 18:02

JayS wrote:Currently there are two lines with 8/yr each.

Once Tejas reaches 16 a year, the IAF will be left with no choice but to induct it to make up for numbers. Trump wants US jobs and SE fighter will go the same way as MMRCA. Gripen will go PAKFA way - Indian money for Swedes with zero gains. IAF pilots have been positive on Tejas flight characteristics and no laundry list of defects like MiG-29 & Su-30. The only other fighter with such a smooth induction was the Mirage 2000. And Russia cannot afford to flood India with cheap Su-7, MiG-21 & MiG-23 that untimely killed the Marut.

srai · Post by **srai** » 26 Dec 2017 18:03

19

How is that even possible? Is the author trying to retire some Mirage-2000 and Jaguars along with all of the MiGs by 2027? Su-30MKI itself will be 14 squadrons. That calculation assumes there will be 5 squadrons only of something else.

Refer to my previous post on this few days ago. 30-38 squadrons easily:
viewtopic.php?f=3&t=7368&start=2560#p2239247

ArjunPandit · Post by **ArjunPandit** » 26 Dec 2017 20:00

srai wrote:19

How is that even possible? Is the author trying to retire some Mirage-2000 and Jaguars along with all of the MiGs by 2027? Su-30MKI itself will be 14 squadrons. That calculation assumes there will be 5 squadrons only of something else.

Refer to my previous post on this few days ago. 30-38 squadrons easily:
viewtopic.php?f=3&t=7368&start=2560#p2239247

OT but i am afraid pakis will start smelling weak IAF and do one JF17==10 Tejas. Just struck me that 17 reverse is '71.

JayS · Post by **JayS** » 26 Dec 2017 20:19

ashishvikas wrote:
JayS wrote:
I think we should also move related posts from last couple of pages to Design your own Fighter thread.

Interestingly while replying to one post on 0.5mtr plug a couple of days ago here, I typed that I would rather have ADA go with 1mtr plug a la NLCA. I first thought of 0.5m each before and after the wing, but that would have moved engine back and wouldn't have helped area curve in rear portion either. So I thought better go with 1mtr plug ahead of wing itself. But then that would reduce static instability margin. So I thought it would be perhaps possible only if canards can be put on. Which seemed highly unlikely a couple of days ago. So I deleted that part of my post thinking its just a jingo dream. But now with the revelation that Canards can be put on LCA Mk2, I would definitely want ADA to go with 1mtr plug or even more if possible and maximize internal volume, the more the better, use all for fuel. There is quite a bit of scope for plug from wave drag perspective and canards will help maintain static instability margin as well as reduce trim drag. Adding half mtr plug would give significant boost to internal fuel if all of it can be used for fuel. I estimate a good 1000-1200ltr Volume availability from this.
JayS Sir, NLCA was planned for 1 meter plug without canards. CD Balaji has been mentioning this to NDTV interview in this video at 3:15. 1 meter plug will give space for 7--kg of fuel along with lighter landing gear.

So, just wanted to understand how different is NLCA with MK2 ?

https://www.youtube.com/watch?v=pzSM3ohvQqE

No Sir or ji please.

I am not sure where exactly the 1m is going on NLCA MK2 ( Kartik posted long time back that it will be 0.5m each ahead and after the cockpit.) So I didnt brought it in consideration. Plus it has LEVCON for static instability margin manipulation additionally. Another thing is it would have bulkier MLG seating just behind the CG. So forward movement of CG due to plug is mitigated somewhat or can be easily managed by slight movement of MLG or new fuel tanks to be added. While for LCA MK2, No significant change happening aft of wing LE attachment point. I gave it some thought and points like these make me feel that while NLCA MK2 can live without canard, LCA MK2 will most probably need it if it wants to go longer than 13.7m. Infact if they are willing to deal with canards they should not restrict to 1m plug as well and go as long as possible to maximize internal volume.

Adding canards is not a trivial matter. Tailless delta with canard have some disadvantages in controlling. Gripen paid the price in two accidents early on. When you have multiple surfaces doing basically same job and have to split total controlling power in manoeuvring and stabilizing things become complicated. Which one of the two available surfaces to use, when and how much? No straightforward answers. Plus complicated actuation system. Then designer needs to think if the added controlling power really worth the complexities..? If ADA can do it now, well and good. If LCA looks like Gripen and Rafale, maybe half the ill-informed and uninformed folks will look favourably to it. LOL

Rishi_Tri · Post by **Rishi_Tri** » 26 Dec 2017 20:20

srai wrote:19

How is that even possible? Is the author trying to retire some Mirage-2000 and Jaguars along with all of the MiGs by 2027? Su-30MKI itself will be 14 squadrons. That calculation assumes there will be 5 squadrons only of something else.

Refer to my previous post on this few days ago. 30-38 squadrons easily:
viewtopic.php?f=3&t=7368&start=2560#p2239247

6 Squadrons of MK1A very much possible by 2027.

Assuming constant run of 16 LCAs per year from 2018 to 2027 (years 2019+ better for actual LCAs rolled out), shall mean 160 if not more. That makes it IOC - 1 Squadron
FOC - 1 Squadron
MK1A - 6 Squadrons

If development proceeds as planned, perhaps even 1-2 squadrons of Mk2. Add to this the possibility that IOC, FOC may go through an upgrade at least to MK1A.

Haridas · Post by **Haridas** » 26 Dec 2017 21:00

deejay wrote: Alarmingly, the report quotes an air force reply, stating, “14 squadrons of MiG 21, 27 & 29 are due for de-induction in next 10 years, the present level of 33 squadrons will further go down to 19 by 2027, and may further reduce to 16 by 2032.”

Two things here - Mig 29 sqns - are we expecting Mig 29s to retire and also the number down to 19 from 33 (33-14=19) assumes no fresh inductions.

What is the fatigue life of Mig 29? Factor in when is the first inducted Mig29K Sqn is expected to retire due to old age. Just like the last of Mi8 retiring earlier this month

srin · Post by **srin** » 26 Dec 2017 21:03

JayS wrote: I am not sure where exactly the 1m is going on NLCA MK2 ( Kartik posted long time back that it will be 0.5m each ahead and after the cockpit.) So I didnt brought it in consideration. Plus it has LEVCON for static instability margin manipulation additionally. Another thing is it would have bulkier MLG seating just behind the CG. So forward movement of CG due to plug is mitigated somewhat or can be easily managed by slight movement of MLG or new fuel tanks to be added. While for LCA MK2, No significant change happening aft of wing LE attachment point. I gave it some thought and points like these make me feel that while NLCA MK2 can live without canard, LCA MK2 will most probably need it if it wants to go longer than 13.7m. Infact if they are willing to deal with canards they should not restrict to 1m plug as well and go as long as possible to maximize internal volume.

Please correct me if I'm wrong.

Take the Mirage 2000. Tail-less like Tejas, but simple delta. So very high ITR, good high speed characteristics. But low STR and high drag at low speeds.

Now, Tejas Mk1. Tail-less and compound delta. High ITR. And reduced drag due to the lower sweep angle on the inside and higher sweep angle on the outside. There are still issues with higher landing speed etc esp for naval version.

So, naval version has moveable levcons (similar to / better than LERX on mig-29 / f-18) to reduce landing speed and increase lift at low speeds for carrier take offs and landings.

Where does canard fit into all this ? I keep reading that Mirage has excellent maneuverability, but it doesn't have canards. So, why canards even considered (whether finalized or not) ?

fanne · Post by **fanne** » 26 Dec 2017 21:03

su30mki ITSELF (@313 TOTAL, unless that is bad reporting, we have only ordered 273) is 17 SQ (@18 planes, as it does not need two trainers per sq). Add 2 Rafael, 3 mirages (the upgrade itself goes on for another 7-8 years), at least 2-3 sq of LCA (I would say all 6, but even if someone pulls the plug, maybe we have UPA-3 and St. Anthony son is our def minister), 5 sq of Jags, 3 of Mig 29 (why would you retire them?). We will be at 33 SQ minimum. in next 5-10 years, following may happen with very high probability - More SU30MKI (2-4 sq), 3-6 more LCA sq, 2 MORE Rafael, maybe 1 more of Mirage 2000 ex Qatar= 8 to 15 more SQ.

VKumar · Post by **VKumar** » 26 Dec 2017 22:32

deejay wrote:Actually, flightglobal is amazingly sharp in details. Very few articles quote numbers and very few bother to cover the history / geography. I may not like the narrative or some numbers may be here / there but Mike Rajkumar is an interesting fellow to watch out for. Narrative yahan bhi set ho raaha hai. Hints are available in the mention of F16, Gripen and Tejas Mk 2.

His take on IAF sqn nos are also interesting.

A recently released parliamentary report on India’s defence forces, states that the air force is now down to 33 active fighter squadrons as against the authorised strength of 42.

Alarmingly, the report quotes an air force reply, stating, “14 squadrons of MiG 21, 27 & 29 are due for de-induction in next 10 years, the present level of 33 squadrons will further go down to 19 by 2027, and may further reduce to 16 by 2032.”
Two things here - Mig 29 sqns - are we expecting Mig 29s to retire and also the number down to 19 from 33 (33-14=19) assumes no fresh inductions. These also exclude induction of already contracted Tejas and Rafale. So yes, numbers are representing worst case scenarios. Secondly, which Parliamentary report is this?

Don't anticipate MIG 29 to retire by 2030. Even if 1 squadron per year, of LCA joins wef 2019, all Mig squadrons would be replaced by LCA of various versions. Add at least 2 more SU MKI, perhaps 4 more and maybe 4 squadrons of Rafale, we would not only improve total numbers by 2030 but also the technological advancements of the new planes, with better armaments, more uptime would actually see us having effective strength equivalent to more than 42 squadrons of today's mix.

sudeepj · Post by **sudeepj** » 26 Dec 2017 23:48

May be these dire 19 sq in 2030 warnings are Chanakian. Sometimes, the fact that you are going to be stronger in future will bring a planned future conflict into the present, as in 1965.

Will the thales radar that they are flight testing for tejas mean carriage of meteor too?
https://www.thalesgroup.com/en/india/pr ... s-mk1a-lca

JayS · Post by **JayS** » 27 Dec 2017 00:12

srin wrote:
JayS wrote: I am not sure where exactly the 1m is going on NLCA MK2 ( Kartik posted long time back that it will be 0.5m each ahead and after the cockpit.) So I didnt brought it in consideration. Plus it has LEVCON for static instability margin manipulation additionally. Another thing is it would have bulkier MLG seating just behind the CG. So forward movement of CG due to plug is mitigated somewhat or can be easily managed by slight movement of MLG or new fuel tanks to be added. While for LCA MK2, No significant change happening aft of wing LE attachment point. I gave it some thought and points like these make me feel that while NLCA MK2 can live without canard, LCA MK2 will most probably need it if it wants to go longer than 13.7m. Infact if they are willing to deal with canards they should not restrict to 1m plug as well and go as long as possible to maximize internal volume.
Please correct me if I'm wrong.

Take the Mirage 2000. Tail-less like Tejas, but simple delta. So very high ITR, good high speed characteristics. But low STR and high drag at low speeds.

Now, Tejas Mk1. Tail-less and compound delta. High ITR. And reduced drag due to the lower sweep angle on the inside and higher sweep angle on the outside. There are still issues with higher landing speed etc esp for naval version.

So, naval version has moveable levcons (similar to / better than LERX on mig-29 / f-18) to reduce landing speed and increase lift at low speeds for carrier take offs and landings.

Where does canard fit into all this ? I keep reading that Mirage has excellent manoeuvrability, but it doesn't have canards. So, why canards even considered (whether finalized or not) ?

Canards are not "necessary" for high manoeuvrability. Its just they have certain advantages via-a-vis tail planes when compared equally manoeuvrable possible configs of same plane. And certain disadvantages or complexities too. In concept study, the design team has to choose one of a handful possible configs, partly based on the pluses and partly based on ability to handle minuses.

When comparing LCA MK2 with M2K, keep in mind that while M2K is an organic design, MK2 is a extension of an organic design MK1. When you extend, and if the extensions are beyond certain limits, then you ought to have extra features to accommodate the inorganic elements of the extension. Thats expected. Had we went with 15mtr LCA from starting, ADA might as well have found out that canards are indeed helpful and worth the extra complexities. Who knows.

Indranil · Post by **Indranil** » 27 Dec 2017 02:08

JayS wrote:
Canards are not "necessary" for high manoeuvrability.
...
Had we went with 15mtr LCA from starting, ADA might as well have found out that canards are indeed helpful and worth the extra complexities. Who knows.

Exactly.

By the way, plan of record is still 500 mm plug, which means a very small canard, if any. I don't think it will be used for any directional control.

Cybaru · Post by **Cybaru** » 27 Dec 2017 03:08

Any addition of plug will change the wing dimensions correct? LCA has wing fuel tanks correct? that means more fuel in the wings along with fuel tanks in the mid section where the plug goes?

Haridas · Post by **Haridas** » 27 Dec 2017 03:28

Cybaru wrote:Any addition of plug will change the wing dimensions correct?

It is not necessary to change wing.

Rakesh · Post by **Rakesh** » 27 Dec 2017 04:11

https://twitter.com/indiandefencera/sta ... 0191681537 --> LA-5004 (SP-4) prior to getting into Sqn fleet, completing her initial block of flights. After SP-7 (LA-5007) did her maiden flight, will undergo similar process but with a faster pace as the initial hiccups have been left behind. Soon SP-5 (LA-5005) will commence this process.

shiv · Post by **shiv** » 27 Dec 2017 07:26

Question:

brar_w put up a post saying how the F-16 had to be limited to 25.5 deg AoA because after a point the high AoA will prevent airflow from reaching the tail fin thus hampering lateral control and leading to an uncontrolled departure.

I have read elsewhere that one solution that has been tried in other aircraft is to make the tail fin tall so that lateral stability is retained at High AoA

Here is my question: The Tejas has a little window that allows airflow up from underneath the wing to the inboard upper surfaces of the main wings. Would this contribute in any way to retaining some airflow around the tail fin at high angles of attack?

Singha · Post by **Singha** » 27 Dec 2017 09:42

is that why eurofighter and panavia tornado have such tall tails?

Kartik · Post by **Kartik** » 27 Dec 2017 11:08

deejay wrote:Actually, flightglobal is amazingly sharp in details. Very few articles quote numbers and very few bother to cover the history / geography. I may not like the narrative or some numbers may be here / there but Mike Rajkumar is an interesting fellow to watch out for. Narrative yahan bhi set ho raaha hai. Hints are available in the mention of F16, Gripen and Tejas Mk 2.

His take on IAF sqn nos are also interesting.

A recently released parliamentary report on India’s defence forces, states that the air force is now down to 33 active fighter squadrons as against the authorised strength of 42.

Alarmingly, the report quotes an air force reply, stating, “14 squadrons of MiG 21, 27 & 29 are due for de-induction in next 10 years, the present level of 33 squadrons will further go down to 19 by 2027, and may further reduce to 16 by 2032.”
Two things here - Mig 29 sqns - are we expecting Mig 29s to retire and also the number down to 19 from 33 (33-14=19) assumes no fresh inductions. These also exclude induction of already contracted Tejas and Rafale. So yes, numbers are representing worst case scenarios. Secondly, which Parliamentary report is this?

Deejay Sir, even Flight Global no longer can be taken at face value. Gone are the days when a report in FG would be extremely well researched and generally get its facts right. Before Mike Rajkumar, another journos contributed on Indian aerospace to FG, Jay Menon and Neelam Matthews to AW&ST. Even they made some factual errors, but of the lot, Neelam Matthews was probably best. But even she had her bias, which sometimes used to come through. But she did write quite a few good articles for Aviation Week & Space Technology too.

What Mike Rajkumar is suggesting is that the 20 FOC standard Tejas Mk1s will actually be built as Tejas Mk1As instead. Now, if that turns out to be true, we'll know that FG was the first place where this was stated.

JayS · Post by **JayS** » 27 Dec 2017 11:33

Indranil wrote:
JayS wrote:
Canards are not "necessary" for high manoeuvrability.
...
Had we went with 15mtr LCA from starting, ADA might as well have found out that canards are indeed helpful and worth the extra complexities. Who knows.
Exactly.

By the way, plan of record is still 500 mm plug, which means a very small canard, if any. I don't think it will be used for any directional control.

Pitch control you mean..? FOr directional (yaw) control canards would be rather sub-optimal.

JayS · Post by **JayS** » 27 Dec 2017 11:36

Cybaru wrote:Any addition of plug will change the wing dimensions correct? LCA has wing fuel tanks correct? that means more fuel in the wings along with fuel tanks in the mid section where the plug goes?

The idea is no to change the wings. Changing wings is equivalent to a new aircraft, as they say in Aerospace. Even geometric scaling up counts as change in wing. Better not to touch the wings to keep program objectives realistic for a 5-7yr time span.

PS: Thus they are adding plug before the wing starts. That also helps mitigate issue with area curve.

deejay · Post by **deejay** » 27 Dec 2017 11:38

Kartik wrote:...

Deejay Sir, even Flight Global no longer can be taken at face value. Gone are the days when a report in FG would be extremely well researched and generally get its facts right. Before Mike Rajkumar, another journos contributed on Indian aerospace to FG, Jay Menon and Neelam Matthews to AW&ST. Even they made some factual errors, but of the lot, Neelam Matthews was probably best. But even she had her bias, which sometimes used to come through. But she did write quite a few good articles for Aviation Week & Space Technology too.

What Mike Rajkumar is suggesting is that the 20 FOC standard Tejas Mk1s will actually be built as Tejas Mk1As instead. Now, if that turns out to be true, we'll know that FG was the first place where this was stated.

This is exactly my point. Watch out for Mike Rajkumar. The flightglobal guys don't make shoddy numbers without reason." The SEF is in direct competition to Tejas Mk 2" - that is the next import substitution war. The Mig 29s are not retiring, they are being upgraded - 66 of them. 19 Sqn is a mathematical impossibility. We know that Mk 1 contracts are for 40 and not 20.

Mike Rajkumar along with flightglobal is publishing wrong data and I suspect both of them know it.

JayS · Post by **JayS** » 27 Dec 2017 11:42

shiv wrote:Question:

brar_w put up a post saying how the F-16 had to be limited to 25.5 deg AoA because after a point the high AoA will prevent airflow from reaching the tail fin thus hampering lateral control and leading to an uncontrolled departure.

I have read elsewhere that one solution that has been tried in other aircraft is to make the tail fin tall so that lateral stability is retained at High AoA

Here is my question: The Tejas has a little window that allows airflow up from underneath the wing to the inboard upper surfaces of the main wings. Would this contribute in any way to retaining some airflow around the tail fin at high angles of attack?

Not really. Its small amount of air of low energy and it most of it would be dragged in the LE vortex. Its rather tough to keep airflow straight and attached on the centerline at high AoA. One of my pet theories was, the reduced sweep inboard on LCA wing is for keeping the flow on the centerline of the wing as much straight and attached as possible.

JayS · Post by **JayS** » 27 Dec 2017 11:45

Kartik wrote:
deejay wrote:Actually, flightglobal is amazingly sharp in details. Very few articles quote numbers and very few bother to cover the history / geography. I may not like the narrative or some numbers may be here / there but Mike Rajkumar is an interesting fellow to watch out for. Narrative yahan bhi set ho raaha hai. Hints are available in the mention of F16, Gripen and Tejas Mk 2.

His take on IAF sqn nos are also interesting.

Two things here - Mig 29 sqns - are we expecting Mig 29s to retire and also the number down to 19 from 33 (33-14=19) assumes no fresh inductions. These also exclude induction of already contracted Tejas and Rafale. So yes, numbers are representing worst case scenarios. Secondly, which Parliamentary report is this?
Deejay Sir, even Flight Global no longer can be taken at face value. Gone are the days when a report in FG would be extremely well researched and generally get its facts right. Before Mike Rajkumar, another journos contributed on Indian aerospace to FG, Jay Menon and Neelam Matthews to AW&ST. Even they made some factual errors, but of the lot, Neelam Matthews was probably best. But even she had her bias, which sometimes used to come through. But she did write quite a few good articles for Aviation Week & Space Technology too.

What Mike Rajkumar is suggesting is that the 20 FOC standard Tejas Mk1s will actually be built as Tejas Mk1As instead. Now, if that turns out to be true, we'll know that FG was the first place where this was stated.

Not really. IIRC it was mentioned by HAL chairman as well in one of his interviews that the 20FOC planes could be upgraded to Mk1A standard. And if IAF wants the 20 IOC birds can also be upgraded but it will have to a separate contract.

PS: Did some googling. There are references to statement made by HAL Chairman that HAL plans to demonstrate MK1A standard by 2018 so the FOC order will be converted to directly Mk1A standard. (Posting easily available links only)
http://armynews.in/indian-defence-news/ ... ejas-mk1a/
I remember this thing was discussed on LCA thread. But I remember to have seen reference to "FOC upgrade to Mk1A" earlier as well. It was the time when SEF MII thread was taking off. It might be so that HAL chairman wanted to say HAL plans to convert 20 FOC order to Mk1A as they have enough time before FOC order will come up for equipping stage. And the DDM misreported it saying 20FOC will be built as FOC and then upgraded to Mk1A standard later. Or it is possible that the understanding between IAF and HAL is such that 20 FOC will indeed be upgraded to Mk1A standard eventually while IOC batch upgrade is optional. There are previous references to "FOC upgrade to Mk1A" and "IOC upgrade to Mk1A" and its very much possible that entire 123 fleet of LCA will be brought to Mk1A standard.

Indranil · Post by **Indranil** » 27 Dec 2017 11:47

JayS wrote:
Indranil wrote: Exactly.

By the way, plan of record is still 500 mm plug, which means a very small canard, if any. I don't think it will be used for any directional control.
Pitch control you mean..? FOr directional (yaw) control canards would be rather sub-optimal.

You have got mail

Bala Vignesh · Post by **Bala Vignesh** » 27 Dec 2017 17:31

JayS wrote:
The idea is no to change the wings. Changing wings is equivalent to a new aircraft, as they say in Aerospace. Even geometric scaling up counts as change in wing. Better not to touch the wings to keep program objectives realistic for a 5-7yr time span.

This had been bugging me for quite some time. Any change in the wings basically translates to a whole new design with all the testing that it entails. So i was left wondering how would ADA add a fuselage plug fore and aft of the CG without altering the wing size??
I had always assumed ADA knew exactly what the effects of the change were and how the aircraft would respond to it and would have factored it into the timelines they were proposing for the Mk2.
Didn't think they were looking or would look at adding another control surface to mitigate that factor.

JayS · Post by **JayS** » 27 Dec 2017 18:29

Bala Vignesh wrote:
JayS wrote:
The idea is no to change the wings. Changing wings is equivalent to a new aircraft, as they say in Aerospace. Even geometric scaling up counts as change in wing. Better not to touch the wings to keep program objectives realistic for a 5-7yr time span.
This had been bugging me for quite some time. Any change in the wings basically translates to a whole new design with all the testing that it entails. So i was left wondering how would ADA add a fuselage plug fore and aft of the CG without altering the wing size??
I had always assumed ADA knew exactly what the effects of the change were and how the aircraft would respond to it and would have factored it into the timelines they were proposing for the Mk2.
Didn't think they were looking or would look at adding another control surface to mitigate that factor.

Reread the post above again. I missed adding one point. Now added.
Its quite a standard practice in civilian jets to add plugs to enlarge fuselage without touching the wings. Various versions of same family are made in such manner (A319, A320, A321 for example). ADA is proposing the same. Keep the wing untouched, add plug to fuselage ahead of the wing. Even in NLCA when ADA says wing attachment point will be moved 350mm outboard, they are not changing the wing outer surface but internal structure only. New wing = new aircraft, is a thumb rule. Its not like its not doable, or should not be done. If you have enough resources at hand and its worth it, why not.

Previously there was a paper published discussing possible modifications on the front side to improve performance (especially directional stability IIRC) including nose strakes. They considered 4-5 locations for attaching a surface ahead of the wing. This canard thing seems to be continuation of that. Its a continuous thought process, we see it in bits and pieces and thus perhaps feel its sudden.