LCA Tejas: News and Discussions

ramana · Post by **ramana** » 05 May 2016 02:40

srai, Thanks. Quells the extra length business.

member_28932 · Post by **member_28932** » 05 May 2016 14:22

nileshjr wrote:There was never mention about plug in Radome IIRC. The only 'half-a-meter plug' thing I remember is the one which was proposed for MK2 which would come just behind the cockpit. It doesn't make sense to lengthen the Radome. Wouldn't it mess with the visibility over the nose for the Pilot??

No, Redome plug was proposed as the part of improvement of Aerodynamic performance of tejas Mk1 to reduce the Wave drag as per whitecomb's area rule. Pylon reshaping was also proposed to reduce drag. These two design changes are such that we can incorporate them in Mk1 itself to improve their aerodynamic performance substantially. There was a parer which I read here on the forum which showed a design change to reduce the drag substantially.

Philip · Post by **Philip** » 05 May 2016 14:29

Tx VCS.I remember some talk by the US team about "grey-market" eqpt. on the Bison that bamboozled them. The MOD/AIF should've accepted a basic sqd of LCAs MK-1 without the 1A improvements simply as sev. senior former IAF pilots,AMs, etc., advocated,so that the basic qualities of the bird could be acsertained after it was put through its paces. Stuffing as much as one can into such a small aircraft to try and sex it up as an ersatz MK-2,has thus far taken another year of development. Every year lost increases the obsolescence of the aircraft and with the meager production rate mentioned,it is going to be impossible for the LCA to replace the MIGs on a one-for-one basis. Even if production figs improve what will the quality be esp with the first batches? Another bird will be needed. Is the Gripen a patient bird?

JayS · Post by **JayS** » 05 May 2016 15:07

Vipul Dave wrote:
nileshjr wrote:There was never mention about plug in Radome IIRC. The only 'half-a-meter plug' thing I remember is the one which was proposed for MK2 which would come just behind the cockpit. It doesn't make sense to lengthen the Radome. Wouldn't it mess with the visibility over the nose for the Pilot??
No, Redome plug was proposed as the part of improvement of Aerodynamic performance of tejas Mk1 to reduce the Wave drag as per whitecomb's area rule. Pylon reshaping was also proposed to reduce drag. The new research paper which proposes a substantial reduction in drag by changing the design has a new design pylon as a major component of reducing the drag. These two design changes are such that we can incorporate them in Mk1 itself to improve their aerodynamic performance substantially.

Hm..May be I missed the new publication. Could you please provide the link to it??

But I am sceptical. I don't see how increasing Radome fineness ratio improves Area ruling. This does not in any way reduces the kink at the cockpit. Plus it would be bad for visibility of the pilot over the nose.

Singha · Post by **Singha** » 05 May 2016 15:31

nileshjr wrote:There was never mention about plug in Radome IIRC. The only 'half-a-meter plug' thing I remember is the one which was proposed for MK2 which would come just behind the cockpit. It doesn't make sense to lengthen the Radome. Wouldn't it mess with the visibility over the nose for the Pilot??

it was once spoken off to accomodate the meatier back end of aesa radar

member_28932 · Post by **member_28932** » 05 May 2016 15:56

[/quote]

Hm..May be I missed the new publication. Could you please provide the link to it??

But I am sceptical. I don't see how increasing Radome fineness ratio improves Area ruling. This does not in any way reduces the kink at the cockpit. Plus it would be bad for visibility of the pilot over the nose.[/quote]

Sir,

It is an old paper . Pl find here with the reference.

One of the major out come of sea level trial of Tejas
is that the drag of the aircraft is high such that the aircraft
could not reach the supersonic Mach number at sea level.
The components contributing for the maximum drag rise
has been identified and improvement methods were worked
out.
Nose cone extension using a Plug: The major component
of drag at higher speed is the wave drag. This can be
minimized by following the Whitcomb’s Area rule for the
aerodynamic configuration design. The cross sectional area
variation of LCA along the length of fuselage is shown
in Fig 12. Between station X = 5000mm & 6000mm there
is a sudden increase in area. By smoothing this sudden
rise, the wave drag can be minimized. A possible solution
proposed is the extension of nose cone by introducing a
Plug. The detailed analysis of this design and its implementation
plan is being worked out.
Pylon reshaping: Another area for improvement is identified
as the pylon reshaping. The leading edge of all the pylons
are blunt and it can be reshaped aerodynamically for the
drag reduction.

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

shiv · Post by **shiv** » 05 May 2016 17:06

Vipul Dave wrote:
nileshjr wrote:There was never mention about plug in Radome IIRC. The only 'half-a-meter plug' thing I remember is the one which was proposed for MK2 which would come just behind the cockpit. It doesn't make sense to lengthen the Radome. Wouldn't it mess with the visibility over the nose for the Pilot??
No, Redome plug was proposed as the part of improvement of Aerodynamic performance of tejas Mk1 to reduce the Wave drag as per whitecomb's area rule. Pylon reshaping was also proposed to reduce drag. These two design changes are such that we can incorporate them in Mk1 itself to improve their aerodynamic performance substantially. There was a parer which I read here on the forum which showed a design change to reduce the drag substantially.

There are enough keywords here to locate the source and the first one that comes up is a post by ersakthivel on DFI quoting the following 2009 paper from Cemilac
http://drdo.gov.in/drdo/pub/dss/2009/main/2-CEMILAC.pdf

One of the major out come of sea level trial of Tejas
is that the drag of the aircraft is high such that the aircraft
could not reach the supersonic Mach number at sea level.
The components contributing for the maximum drag rise
has been identified and improvement methods were worked
out.
Nose cone extension using a Plug:
The major component
of drag at higher speed is the wave drag. This can be
minimized by following the Whitcomb’s Area rule for the
aerodynamic configuration design. The cross sectional area
variation of LCA along the length of fuselage is shown
in Fig 12. Between station X = 5000mm & 6000mm there
is a sudden increase in area. By smoothing this sudden
rise, the wave drag can be minimized. A possible solution
proposed is the extension of nose cone by introducing a
Plug. The detailed analysis of this design and its implementation
plan is being worked out.
Pylon reshaping:
Another area for improvement is identified
as the pylon reshaping. The leading edge of all the pylons
are blunt and it can be reshaped aerodynamically for the
drag reduction. The in-board pylon before modification i

Here is a link to ersakthivel's post
http://defenceforumindia.com/forum/thre ... st-1108110

SaiK · Post by **SaiK** » 05 May 2016 17:10

ramana and srai may copy that in the radome dhaaga. that 30% efficiency is simply not a joke to waste time to invest in. it has a doubled edged sword technology for stealth skins as well.

https://www.cobham.com/media/917782/cob ... ies_fa.pdf
resin transfer moulding

JayS · Post by **JayS** » 05 May 2016 18:08

Singha wrote:
nileshjr wrote:There was never mention about plug in Radome IIRC. The only 'half-a-meter plug' thing I remember is the one which was proposed for MK2 which would come just behind the cockpit. It doesn't make sense to lengthen the Radome. Wouldn't it mess with the visibility over the nose for the Pilot??
it was once spoken off to accomodate the meatier back end of aesa radar

Makes sense for larger Radar. I don't remember this one though, might have missed it.

Vipul Dave wrote: Sir,

It is an old paper . Pl find here with the reference.

One of the major out come of sea level trial of Tejas
is that the drag of the aircraft is high such that the aircraft
could not reach the supersonic Mach number at sea level.
The components contributing for the maximum drag rise
has been identified and improvement methods were worked
out.
Nose cone extension using a Plug: The major component
of drag at higher speed is the wave drag. This can be
minimized by following the Whitcomb’s Area rule for the
aerodynamic configuration design. The cross sectional area
variation of LCA along the length of fuselage is shown
in Fig 12. Between station X = 5000mm & 6000mm there
is a sudden increase in area. By smoothing this sudden
rise, the wave drag can be minimized. A possible solution
proposed is the extension of nose cone by introducing a
Plug. The detailed analysis of this design and its implementation
plan is being worked out.
Pylon reshaping: Another area for improvement is identified
as the pylon reshaping. The leading edge of all the pylons
are blunt and it can be reshaped aerodynamically for the
drag reduction.

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

I know this one. But there seems to be something odd in above paragraph. We know that the kink in the c/s area curve is behind the cockpit. The paper shows exact location - slightly after 5m from the front. The flat portion between 4m-5m needs to be eliminated and/or the kink after 5m needs to be spread out over larger length. That flat portion part is the cockpit. In one of the newer publications, they have precisely enlarged the c/s at these locations to smoothen the curve. This makes sense. I don't know how putting plug on the nose cone will do anything to alleviate the problem. Nose cone is far too much upstream to have any effect on the cockpit area. Note that it also makes sense to place a 0.5m plug after the cockpit but ahead of wing LE. That straightaway reduces that sudden increase in c/s area. So slight fattening of cockpit area with 0.5m plug behind the cockpit makes the curve really nice looking. But nose cone, doesn't make sense to me.

It is possible that this nose cone plug was proposed for some other reason as well, such as what Singha ji stated. But it was later dropped as the other reason/s perhaps became irrelevant and the aerodynamic gain alone was never enough to justify the change.

Kartik · Post by **Kartik** » 05 May 2016 21:43

It was dropped and the plug was for 0.5m, to be added behind the cockpit and just fore of the intake.

Dileep · Post by **Dileep** » 07 May 2016 12:44

Chaiwalas say that the top brass are going to fly the bird in the coming days, which would give a lot of boost to the programme. The team is now highly optimistic. One would wish that the RM fly the rear seat of the trainer.

SaiK · Post by **SaiK** » 07 May 2016 15:50

why not modi ji? we couldn't have maun ji for stealth reasons!

Dileep · Post by **Dileep** » 07 May 2016 19:31

^^Well, no one asked that question! I think it is a given that the SPG will not allow that to happen, being single engined and all.

JayS · Post by **JayS** » 08 May 2016 01:58

About time. Just the other day i was thinking someone fror higher ups flying in Tejas will be a nice PR. Now that its officially inducted in AF atleast ACM should do a PR flight, if not sm1 from govt. Surely ACM should be able to fly single engine bird.

Cybaru · Post by **Cybaru** » 08 May 2016 03:48

Dileep wrote:Chaiwalas say that the top brass are going to fly the bird in the coming days, which would give a lot of boost to the programme. The team is now highly optimistic. One would wish that the RM fly the rear seat of the trainer.

+1
That is great news!

Gagan · Post by **Gagan** » 08 May 2016 04:07

Air Chief is also a prisoner to the single engined rule I think...

fanne · Post by **fanne** » 08 May 2016 04:31

Then how did ACM Tipnis flew back seat on Mirage 2000 in Operation Safedsagar?

Gagan · Post by **Gagan** » 08 May 2016 09:30

Really?
I guess they are not then.
I understood that the VVIPs - President, PM, Def Min, Service Chiefs ( and Rober(t) Vadra - just kidding) were not allowed on single engined aircraft - oh and no security checks in airports too

But ACM tipnis had actually commanded that squadron back in the day. He participated in one of the strikes on tiger hill too.

SaiK · Post by **SaiK** » 08 May 2016 10:18

^from the fact that a security is always with them, they don't need security check. not from the fact to ridicule non-VVIPs whatsoever, imho. if ain't the understanding that way, then I would like to make that clear or get clarified if it is that way.

srai · Post by **srai** » 08 May 2016 10:40

Gagan wrote:Air Chief is also a prisoner to the single engined rule I think...

ACM Tipnis flew MiG-21 solo when the media was calling it "the flying coffin" back in 2002.

Karan M · Post by **Karan M** » 08 May 2016 16:59

He also undertook a sortie in a Mirage 2000 over Kargil.

Karan M · Post by **Karan M** » 08 May 2016 16:59

Fanne got it earlier.

Great memory SRai

shiv · Post by **shiv** » 08 May 2016 19:28

In the MiG 21 - 50 years book, Tipnis has written a great article pointing out how the aircraft has been needlessly maligned. The single engine rule has nothing to do with the air force. Imagine that you work for Apple and your CEO uses an Android phone. You cannot head an Air Force and say that some aircraft flown by some people are too unsafe for me to fly.

The single engine rule is to protect the fat asses of our fraudulent ba$tard Delhi politicians and baboos on Republic day because they are shit scared that single engines will fail while they are quite happy to let our young air warriors fly them. Just so we don't promote fiction on here

Karan M · Post by **Karan M** » 08 May 2016 19:57

They weren't worried single engines would fail IIRC but that bird strikes at Hindon AFB were considered a very big hazard.
Later on MiG-29s were brought in there - by memory.

But same issue all over India. Illegal construction, squatters, illegal abattoirs - all create a bird hazard right around major AFB.

Babus then sit on funding for innovative measures. But IIRC bird strike hazard has gone down with lot of IAF investment and jugaad.

From a decade ago.

MiG-21 crashes after take-off, pilot killed

DHNS,Bangalore:

A MiG-21 fighter jet of the Indian Air Force (IAF) crashed shortly after take-off at the Bangalore Airport on Wednesday afternoon. Test pilot Sq Leader K R Murthy was killed in the crash while co-pilot and flight test engineer K D Bhat, ejected safely. There was no casualty on the ground, as the plane crashed into the swamps close to the runway, Airports Authority of India (AAI) sources said.

The plane, which took off on a routine sortie from the Aircraft and Systems Testing Establishment (A&STE) of the IAF at 12.45 pm, faced a loss of thrust hardly five minutes after getting airborne. Sq leader Murthy ejected along with Bhat. The aircraft reportedly drifted south, before crashing with a ball of flame 100 metres left to the shoulder of the runway. It is presumed that strong winds from the north could have drifted the ejected parachute of Sq leader Murthy into the flames, resulting in its burnout. He was immediately shifted to Command Hospital, where he succumbed to internal injuries at 3 pm, the IAF sources said. Sq leader Murthy, a native of Hyderabad in his early 30s, was a flight test pilot at the A&STE. He is survived by his wife.

Speaking to Deccan Herald, IAF spokesperson Wing Commander Raghunath said that according to preliminary investigations, the crash was suspected to be due to a bird-hit at a low altitude during take-off. Burned remains of a bird were found on the runway, he said. The pilots reportedly heard a thud and felt a loss of thrust, he added. Mr Raghunath said both the pilots were highly qualified and experienced.

A court of enquiry headed by Air Commodore P B Patil with an accident investigation team from the Air Head Quarters is probing into the crash.

As many as 161 pilots have lost their lives in 321 MiG crashes in the country over more than a decade. The MiG-21 fleet, dubbed Ã¢â¬Åflying coffinsÃ¢â¬Â by critics for its record of fatalities, has done over 5,83,000 sorties in the last 10 years, which had resulted in 115 accidents with 50 fatalities.

CRASH & AFTER

Airport returns to normalcy

Bangalore, DHNS: According to Airports Authority of India (AAI) sources, the air traffic at Bangalore airport was suspended for nearly two hours after the crash. The runway, which was not damaged, was opened after two hours.

The wreckage was far beyond the runway and the aircraft was broken into two pieces, the sources added. The first aircraft to take off after the crash was the Indian Airlines flight to Mumbai, followed by another flight to New Delhi.

shiv · Post by **shiv** » 08 May 2016 20:23

Bird strike risk is no reason for senior IAF officers to avoid single engines.

Rahul M · Post by **Rahul M** » 08 May 2016 20:42

Karan M wrote:He also undertook a sortie in a Mirage 2000 over Kargil.

ACM Tipnis was also in the cockpit of one of two chase mirages when LCA took to the skies for the first time on Jan 4, 2001.
a true lead from the front leader.
http://www.thehindu.com/2001/01/05/stories/01050002.htm

it was the 2 seat mirage-2000 though.

srai · Post by **srai** » 10 May 2016 18:04

Tejas Aerobatics Display 2015 - diagram of maneuvers

Aero India-2015 - Tejas video

Karan M · Post by **Karan M** » 10 May 2016 18:23

Shiv wrote:Bird strike risk is no reason for senior IAF officers to avoid single engines.

No, but its a risk for AF planners when considering single engine ops in bases right next to cities or which have to do AD for that city.
Things have improved though. We (touchwood) don't hear of so many incidents as we once used to.

shiv · Post by **shiv** » 10 May 2016 18:38

Karan M wrote:
Shiv wrote:Bird strike risk is no reason for senior IAF officers to avoid single engines.
No, but its a risk for AF planners when considering single engine ops in bases right next to cities or which have to do AD for that city.
Things have improved though. We (touchwood) don't hear of so many incidents as we once used to.

Keeping birds off runways is a constant activity on all runways - but for civilians like us the most discernible technique is gunshots heard during Aero India flying displays by designated people to scare birds away. Not sure if they use real shotguns or simply something that makes a loud report. Probably the latter. But the topic came up because someone said that senior IAF officers are not supposed to fly single engined aircraft which is complete rubbish.

For birds this might be what I have seen at Aero India
https://en.wikipedia.org/wiki/Bird_scar ... ge_scarers

NRao · Post by **NRao** » 10 May 2016 18:42

Karan M wrote:
Shiv wrote:Bird strike risk is no reason for senior IAF officers to avoid single engines.
No, but its a risk for AF planners when considering single engine ops in bases right next to cities or which have to do AD for that city.
Things have improved though. We (touchwood) don't hear of so many incidents as we once used to.

From 2013:

India Buys Bird-Strike Radars

As congestion increases, avoiding collisions between aircraft and birds is becoming a more pressing issue. The Indian Air Force, which conducts many operational and training flights and often at very low level, attributes around 10 percent of accidents to bird hits. It took the lead last year by issuing global bids to four companies for 45 bird detection and monitoring radar systems (BDRS) to be installed at airports and air bases across India.

And, then an entire issue on bird strikes from the IAF.

Abhay_S · Post by **Abhay_S** » 10 May 2016 18:59

shiv wrote:Bird strike risk is no reason for senior IAF officers to avoid single engines.

http://www.livefistdefence.com/2014/10/ ... rshal.html

Saturday, October 18, 2014

'Time To Go, Ram': When An Indian Air Marshal Punched Out Of A Mirage 2000

suryag · Post by **suryag** » 14 May 2016 08:49

amazing video, recently shot, jingo khush hua

The making of IAF's Tejas LCA- NEWS9

srai · Post by **srai** » 14 May 2016 09:22

suryag wrote:amazing video, recently shot, jingo khush hua

The making of IAF's Tejas LCA- NEWS9

Must watch! Finally, we are beginning to get good coverage of the LCA production activities and facilities!!! Well done News 9

Shreeman · Post by **Shreeman** » 14 May 2016 09:59

I dont think the staircase is carbon composite at all. It just looks like a home welded metal contraption. They just drive around with it hanging by the side. It will fall off some day. Why cant they import some decent technology for making staircases?

edit -- and on a serious note I can see why they dont want to share this level of access. some processes might end up being criticised to where implementing improvements is no longer avoidable.

vina · Post by **vina** » 14 May 2016 10:37

AFAIK, Cobham Quartz radome should exactly be the same dimensions as the indigenous composite one it is replacing. There was an RFI with the drawings. The materials used on the Cobham offers greater radar transparency and hence offers 30 km improvement in detection ranges. It is supposed to be relatively simple plug-in replacement akin to replacing an LRU. It only should require some limited numbers of verification trials.

As far as the additional 0.5m plug behind the cockpit goes, that was proposed for Mk.2. Two different things.

It is not as straight forward as that. There could have been "issues" with the original nose cone design (the ideal ones are Haack series bodies, like the Von Karmann ogive) and that could have been "remedied" with the new guartz nose cone, and achieved both in terms of aerodynamic improvement as well as radar transparency / effectiveness. Sort of killing two birds in one stone.

The area ruling thing is different and would have required the 0.5 m plug in the fuselage around just behind the canopy (would have smoothened out the area curve and also improved the fineness ratio and probably brought it in line with a more ideal Saars-Haack body shape).

JMT and all the rest of it of course.

vcsekhar · Post by **vcsekhar** » 14 May 2016 12:20

srai wrote:
suryag wrote:amazing video, recently shot, jingo khush hua

The making of IAF's Tejas LCA- NEWS9

Must watch! Finally, we are beginning to get good coverage of the LCA production activities and facilities!!! Well done News 9

Nice video but looks like they "borrowed" the mirage footage from the french film Chevaliers du ceil or Gladiators of the Sky. And.. why they hell did they have to constantly play the top gun soundtrack in the background, very irritating and a copyright violation to say the least!!!

BTW this is a cheesy film but has awesome air to air footage of the mirage 2000.

JayS · Post by **JayS** » 14 May 2016 12:36

Amazing. Thanks for posting. Jingo Khush Hua.

Thanks for posting. So the construction work going on is for Squadron facility. That's interesting to know.

member_28990 · Post by **member_28990** » 14 May 2016 13:07

here is one in hindi. very bombastic

shiv · Post by **shiv** » 14 May 2016 14:11

Any American weapon highlighted on History channel or Discovery is full of bombast. Chinese shows too, and even Pakis about the little they make. Somehow Indians thought British style understatement is good and ended up being too diffident and too apologetic

srai · Post by **srai** » 14 May 2016 15:38

vina wrote:
AFAIK, Cobham Quartz radome should exactly be the same dimensions as the indigenous composite one it is replacing. There was an RFI with the drawings. The materials used on the Cobham offers greater radar transparency and hence offers 30 km improvement in detection ranges. It is supposed to be relatively simple plug-in replacement akin to replacing an LRU. It only should require some limited numbers of verification trials.

As far as the additional 0.5m plug behind the cockpit goes, that was proposed for Mk.2. Two different things.
It is not as straight forward as that. There could have been "issues" with the original nose cone design (the ideal ones are Haack series bodies, like the Von Karmann ogive) and that could have been "remedied" with the new guartz nose cone, and achieved both in terms of aerodynamic improvement as well as radar transparency / effectiveness. Sort of killing two birds in one stone.

The area ruling thing is different and would have required the 0.5 m plug in the fuselage around just behind the canopy (would have smoothened out the area curve and also improved the fineness ratio and probably brought it in line with a more ideal Saars-Haack body shape).

JMT and all the rest of it of course.

No geometric changes; only improved EM performance. Here's a post by Indranilroy.