LCA News and Discussions

All threads that are locked or marked for deletion will be moved to this forum. The topics will be cleared from this archive on the 1st and 16th of each month.
Manish_Sharma
BRF Oldie
Posts: 4681
Joined: 07 Sep 2009 16:17

Re: LCA News and Discussions

Postby Manish_Sharma » 10 Jun 2010 19:41

Austin wrote:JMT.... It will be the shape of aircraft that will determine most of its stealth , LCA having composite ,RAM coating,being small or having Y duct will not make it stealthy but will definitely lower its overall RCS in clean config , but once you hang those external fuel tanks and A2A and A2G missile on those pylons and in the field conditions they operate it would be any body guess what effect it would have on RCS of aircraft


But still it would count, lets' say su30 or f16 with their nonstealthy intakes would provide additional bonus to the enemy radar complimented with increased RCS due to armament/fuel tanks/jamming or litening pods.

In the next few years new missiles like Meteor are going to be also designed with stealth kept in mind.

Now if Tejas takes off with missiles/fuel tanks heading to battle zone and jettisons fuel tank 200 kms before battlezone after using them up, that will be some less RCS. Still the advantage of having stealthy intake, small size, composites-made non reflecting body and (in case) it is carrying stealthdesigned missiles would help it avoid enemy radar longer then nonstealthy featured a/cs.

Gagan
BRF Oldie
Posts: 11209
Joined: 16 Apr 2008 22:25

Re: LCA News and Discussions

Postby Gagan » 10 Jun 2010 20:18

Adding a 3D thrust vectoring to the LCA will allow it to undertake more violent turns when evading the incoming missile. This will only add to the effect that the aircraft was intending to do without thrust vectoring.

Also another interesting possibility that the USAF was experimenting with was using this to land at very short distances, usning thrust vectoring to maintain high AOA and landing, thereby using very short runway length.

Another immediate application might be higher weapon loads being able to be gotten airborne even if the runway is somewhat short - like in the middle of a war with a compromized runway.

Gaur
Forum Moderator
Posts: 2009
Joined: 01 Feb 2009 23:19

Re: LCA News and Discussions

Postby Gaur » 10 Jun 2010 20:42

Gagan wrote:Adding a 3D thrust vectoring to the LCA will allow it to undertake more violent turns when evading the incoming missile. This will only add to the effect that the aircraft was intending to do without thrust vectoring.

Also another interesting possibility that the USAF was experimenting with was using this to land at very short distances, usning thrust vectoring to maintain high AOA and landing, thereby using very short runway length.

Another immediate application might be higher weapon loads being able to be gotten airborne even if the runway is somewhat short - like in the middle of a war with a compromized runway.

It may not be a very good idea to add tvc to light fighters like tejas. F-16 MATV program tried exactly that with adding tvc to F-16. It was found that total weight increase due to TVC (including counter weight ballast to counter cg) was around 650 kg. This additional wgt negated any advantage in agility that tvc provided. So the effect of adding tvc to an even lighter fighter like Tejas may even have a negative effect. But I somehow get the feeling that all this has been discussed in detail before.

shiv
BRF Oldie
Posts: 34982
Joined: 01 Jan 1970 05:30
Location: Pindliyon ka Gooda

Re: LCA News and Discussions

Postby shiv » 10 Jun 2010 21:05

Gaur wrote:
Gagan wrote:Adding a 3D thrust vectoring to the LCA will allow it to undertake more violent turns when evading the incoming missile. This will only add to the effect that the aircraft was intending to do without thrust vectoring.

Also another interesting possibility that the USAF was experimenting with was using this to land at very short distances, usning thrust vectoring to maintain high AOA and landing, thereby using very short runway length.

Another immediate application might be higher weapon loads being able to be gotten airborne even if the runway is somewhat short - like in the middle of a war with a compromized runway.

It may not be a very good idea to add tvc to light fighters like tejas. F-16 MATV program tried exactly that with adding tvc to F-16. It was found that total weight increase due to TVC (including counter weight ballast to counter cg) was around 650 kg. This additional wgt negated any advantage in agility that tvc provided. So the effect of adding tvc to an even lighter fighter like Tejas may even have a negative effect. But I somehow get the feeling that all this has been discussed in detail before.


The article I linked earlier by Prof Prodyut Das says that TV in a small a/c like the LCA will make it difficult to control - it is already agile. TV is better for making a large aircraft agile.

Gagan
BRF Oldie
Posts: 11209
Joined: 16 Apr 2008 22:25

Re: LCA News and Discussions

Postby Gagan » 10 Jun 2010 21:16

But isn't the EJ200 supposed to have a nozzle at the end for just this 3D vectoring?
Weight issues are something I just didn't take into account. Yes it would add to the weight of a program which is already very weight conscious so to say.

Rahul M
Forum Moderator
Posts: 17016
Joined: 17 Aug 2005 21:09
Location: Skies over BRFATA
Contact:

Re: LCA News and Discussions

Postby Rahul M » 10 Jun 2010 21:45

dhiren, absolutely brilliant idea. but can you read ? please read this, the very first post of this thread.
viewtopic.php?p=883931#p883931
specifically
Please stay on topic.

That means :
a> No comparison with aircraft A,B or C.
b> No half-baked suggestions to improve LCA like "add a laser gun"/"merge DRDO with ISRO " etc etc.
c> NO whining.


@ ALL, especially new members, USE THE NEWBIE THREAD FOR FLIGHTS OF FANCY AND LEAVE THE REGULAR THREADS ALONE !!

Gaur
Forum Moderator
Posts: 2009
Joined: 01 Feb 2009 23:19

Re: LCA News and Discussions

Postby Gaur » 10 Jun 2010 22:01

Gagan wrote:But isn't the EJ200 supposed to have a nozzle at the end for just this 3D vectoring?
Weight issues are something I just didn't take into account. Yes it would add to the weight of a program which is already very weight conscious so to say.

tvc nozzle for EJ200 is just a proposal they may look into in the future. No Eurofighter is flying with tvc at present.

Indranil
Forum Moderator
Posts: 8172
Joined: 02 Apr 2010 01:21

Re: LCA News and Discussions

Postby Indranil » 10 Jun 2010 23:12

Would like to add one more thing. TVC, unlike what most of us believe hardly makes a plane more maneuverable. In extended studies it has been proven that the momentum of the plane is too large, for the TVC to alter path. While using TVC the plane continues to go on its path as it would have without TVC.

It is just the noise pointing ability and the stalling speed at different AoA which changes. This enables the plane to pull off some amazing low speed maneuvers.

For the Tejas, I feel a 2-D TVC might still be used for STOL as pointed by some members, but 3D TVC ... I don't know! But then these things vary incredibly from plane to plane. It is not just the weight, it depends on the planform, the aspect ratio etc etc. We can only discuss generic advantages-disadvantages here. Specific gain-loss has to be researched for the Tejas. Which I am sure the guys at ADA must be upto and I wish to read it sometime in the future!

babbupandey
BRFite
Posts: 180
Joined: 15 Jan 2008 16:53

Re: LCA News and Discussions

Postby babbupandey » 10 Jun 2010 23:51

A question to the gurus, while we are talking of TVC
When TVC is added to an aircraft, while it does add to maneuverability of the aircraft, however, do those maneuvers put some exert some extra stress on the airframe while executing tight turns?
If yes, then is Tejas designed address that?

dhiren k
BRFite -Trainee
Posts: 7
Joined: 20 Mar 2010 17:02

Re: LCA News and Discussions

Postby dhiren k » 11 Jun 2010 01:16

Rahul M wrote:dhiren, absolutely brilliant idea. but can you read ? please read this, the very first post of this thread.
viewtopic.php?p=883931#p883931
specifically
Please stay on topic.

That means :
a> No comparison with aircraft A,B or C.
b> No half-baked suggestions to improve LCA like "add a laser gun"/"merge DRDO with ISRO " etc etc.
c> NO whining.


@ ALL, especially new members, USE THE NEWBIE THREAD FOR FLIGHTS OF FANCY AND LEAVE THE REGULAR THREADS ALONE !!

Dear Mr. Moderator,
I was nor giving any half baked suggestion. Have you ever seen the LCA flying over bangalore, half the time its flying inverted, so I was just thinking that may be HAL+IAF was exploring this idea.
Anyway, how was I off-topic ? Its an LCA discussion thread and I was not talking about su30 or f16 as some people above

Rahul M
Forum Moderator
Posts: 17016
Joined: 17 Aug 2005 21:09
Location: Skies over BRFATA
Contact:

Re: LCA News and Discussions

Postby Rahul M » 11 Jun 2010 01:28

I can't help you if you can't understand how it is off-topic but be advised that you will be warned/banned if you continue to post OT stuff in this thread or elsewhere. at the end of the day, it is my and other mods' call as yo what is OT, so an argument on these lines is not going to help you.

nikhil_p
BR Mainsite Crew
Posts: 378
Joined: 07 Oct 2006 19:59
Location: Sukhoi/Sukhoi (Jaguars gone :( )Gali, pune

Re: LCA News and Discussions

Postby nikhil_p » 11 Jun 2010 01:35

dhiren k wrote:Dear Mr. Moderator,
I was nor giving any half baked suggestion. Have you ever seen the LCA flying over bangalore, half the time its flying inverted, so I was just thinking that may be HAL+IAF was exploring this idea.
Anyway, how was I off-topic ? Its an LCA discussion thread and I was not talking about su30 or f16 as some people above


Dhiren - please read about basic physics of lift and how an aircraft wing works. Aircraft wings are basically designed to create a low pressure zone ABOVE the wing, as you may know, things move from high pressure to low pressure, this is basically what provides lift. If you invert the wing, the aircraft will have a low pressure zone downwards, which will basically pull the a/c downwards.
An aircraft is able to fly upside down for extended periods mainly due to the inertia of the aircraft body, however if it does so for an extended period of time it will follow a ballistic trajectory.

I am no GURU but yes, I love applying the basic theories that I have learnt in my science education!

However, this is OT and I believe this should be moved to the NOOB thread.

And yes a simple experiment. Take a dinner plate (not glass) and go to an open area. Throw it like a frisbee (upside down...the part where you eat downwards). Mark the distance. Now from the same place where you threw the first time, throw the plate right side up. See what happens. You will get the gist of what I tried explaining here.

HariC
BRFite
Posts: 358
Joined: 01 Jan 1970 05:30

Re: LCA News and Discussions

Postby HariC » 11 Jun 2010 01:40

nikhil_p wrote:this is basically what provides lift. If you invert the wing, the aircraft will have a low pressure zone downwards, which will basically pull the a/c downwards.
An aircraft is able to fly upside down for extended periods mainly due to the inertia of the aircraft body, however if it does so for an extended period of time it will follow a ballistic trajectory.


I am sorry.. ... but what you stated is also in the realm of djinn phijicks.

when you roll the ac upside down, you wont keep your nose at the horizon, you will push the stick forward and keep the nose above the horizon - giviing your inverted wing a higher angle of attack than it would have flying level. provided there is enough fuel supply to the engine and the engine runs, it can go all the way to kathmandu inverted.

ofcourse all this doesnt mean dhiren gets away with it.. bash the noobie, bash the nooobie!

nikhil_p
BR Mainsite Crew
Posts: 378
Joined: 07 Oct 2006 19:59
Location: Sukhoi/Sukhoi (Jaguars gone :( )Gali, pune

Re: LCA News and Discussions

Postby nikhil_p » 11 Jun 2010 01:43

HariC wrote:
nikhil_p wrote:this is basically what provides lift. If you invert the wing, the aircraft will have a low pressure zone downwards, which will basically pull the a/c downwards.
An aircraft is able to fly upside down for extended periods mainly due to the inertia of the aircraft body, however if it does so for an extended period of time it will follow a ballistic trajectory.


I am sorry.. bash the noobie ... but what you stated is also in the realm of djinn phijicks.


Hari garu...I was trying to make it as zimple as possible using the wing design hypothesis. by extended period I mean a few seconds at most in level flight. And doesn't hurt to add a bit of BLING does it...

OT post...SORRY!
Last edited by nikhil_p on 11 Jun 2010 01:53, edited 1 time in total.

dhiren k
BRFite -Trainee
Posts: 7
Joined: 20 Mar 2010 17:02

Re: LCA News and Discussions

Postby dhiren k » 11 Jun 2010 01:46

nikhil_p wrote:
dhiren k wrote:Dear Mr. Moderator,
I was nor giving any half baked suggestion. Have you ever seen the LCA flying over bangalore, half the time its flying inverted, so I was just thinking that may be HAL+IAF was exploring this idea.
Anyway, how was I off-topic ? Its an LCA discussion thread and I was not talking about su30 or f16 as some people above


Dhiren - please read about basic physics of lift and how an aircraft wing works. Aircraft wings are basically designed to create a low pressure zone ABOVE the wing, as you may know, things move from high pressure to low pressure, this is basically what provides lift. If you invert the wing, the aircraft will have a low pressure zone downwards, which will basically pull the a/c downwards.
An aircraft is able to fly upside down for extended periods mainly due to the inertia of the aircraft body, however if it does so for an extended period of time it will follow a ballistic trajectory.

I am no GURU but yes, I love applying the basic theories that I have learnt in my science education!


However, this is OT and I believe this should be moved to the NOOB thread.

And yes a simple experiment. Take a dinner plate (not glass) and go to an open area. Throw it like a frisbee (upside down...the part where you eat downwards). Mark the distance. Now from the same place where you threw the first time, throw the plate right side up. See what happens. You will get the gist of what I tried explaining here.


But still an a/c with T/W ratio > 1 could do so for an extended period, perhaps just enough to get the payload delivered. Anyways, if it is pure speculation from my part, plz drop the discussion.

putnanja
BRF Oldie
Posts: 4464
Joined: 26 Mar 2002 12:31
Location: searching for the next al-qaida #3

Re: LCA News and Discussions

Postby putnanja » 11 Jun 2010 01:47

dhiren k wrote:Dear Mr. Moderator,
I was nor giving any half baked suggestion. Have you ever seen the LCA flying over bangalore, half the time its flying inverted, so I was just thinking that may be HAL+IAF was exploring this idea.
Anyway, how was I off-topic ? Its an LCA discussion thread and I was not talking about su30 or f16 as some people above


It flies inverted once in while. If we walk backwards once in a while, should we start doing everything backwards?

Please read up a little on stealth, and also on the way the wings are designed, principles of lift etc. If you post without doing basic research, other knowledgeable postors will just tear it up, and it will lead to thread distractions and hence OT.

If you are an newbie, please post in the newbie thread where there is less chance of diversions, and if question is genuine, others will try to answer it. There is no embarrassment in posting in newbie threads, many experienced postors post there too, for no one is expert in everything.

shiv
BRF Oldie
Posts: 34982
Joined: 01 Jan 1970 05:30
Location: Pindliyon ka Gooda

Re: LCA News and Discussions

Postby shiv » 11 Jun 2010 06:01

dhiren k wrote: Have you ever seen the LCA flying over bangalore, half the time its flying inverted, so I was just thinking that may be HAL+IAF was exploring this idea.

My reply here
viewtopic.php?f=3&t=4290&p=886166#p886166
Last edited by shiv on 11 Jun 2010 06:24, edited 1 time in total.

shiv
BRF Oldie
Posts: 34982
Joined: 01 Jan 1970 05:30
Location: Pindliyon ka Gooda

Re: LCA News and Discussions

Postby shiv » 11 Jun 2010 06:19

Here is what Prof Prodyut Das says about thrust vectoring:
Thrust Vectoring (TV):
The idea is simple but any mechanical designer will realise the complexity and the difficulty of designing a reliable TV system. For an aircraft with inertia of the Su-30, TV is essential for handling at low airspeeds. For an aircraft the size of the LCA whose yaw inertia is approximately 13 times less fitting TV will make it uncontrollable. You have enough problems with reliable and stable controls as it is.


The article is available for download here
http://rapidshare.com/files/377207669/c ... impler.pdf

suraj p
BRFite -Trainee
Posts: 43
Joined: 23 Oct 2009 08:10

Re: LCA News and Discussions

Postby suraj p » 11 Jun 2010 07:04

A regional newspaper 'Eenadu' from AP reported that LCA has successfully completed its hot weather trials in its new LSP (4/5) form. It states that Tejas was baked at 45c and later every avionics hardware was tested. The officials were happy. If I am not wrong, LSP(4/5) with MMR, avionics and in weapons configuration will be put into 'Nagpur' test to check for consistency. I am not sure if this reporter is talking about that particular test. If all goes well is next-stop Jaisalmer for weapons test ?

I take 'Eenadu' stories with pinch of salt. However sometimes, it breaks fresh news too. IF this is old news, please ignore!


http://eenadu.net/story.asp?qry1=21&reccount=31
Last edited by suraj p on 11 Jun 2010 08:10, edited 1 time in total.

Dileep
BRF Oldie
Posts: 5837
Joined: 04 Apr 2005 08:17
Location: Dera Mahab Ali धरा महाबलिस्याः درا مهاب الي

Re: LCA News and Discussions

Postby Dileep » 11 Jun 2010 07:57

shiv wrote:For an aircraft the size of the LCA whose yaw inertia is approximately 13 times less fitting TV will make it uncontrollable. You have enough problems with reliable and stable controls as it is.


The unstable design of tejas would make it extremely complicated to boot.

Vikram W
BRFite -Trainee
Posts: 74
Joined: 12 May 2010 02:23

Re: LCA News and Discussions

Postby Vikram W » 11 Jun 2010 08:21

So india produces AL 31 engines for the MKIs under deep tech transfer from russia.The engine does about 125 kN in thrust. Why cant we use this engine for apno tejas ? i know its about 400 kilos heavier but shouldnt the 30kN of thurst over the 404 more than compensate ?
and we dont have to pay no Snecma royalties for kaveri upgrades.

shiv
BRF Oldie
Posts: 34982
Joined: 01 Jan 1970 05:30
Location: Pindliyon ka Gooda

Re: LCA News and Discussions

Postby shiv » 11 Jun 2010 08:28

Vikram W wrote:So india produces AL 31 engines for the MKIs under deep tech transfer from russia.The engine does about 125 kN in thrust. Why cant we use this engine for apno tejas ? i know its about 400 kilos heavier but shouldnt the 30kN of thurst over the 404 more than compensate ?
and we dont have to pay no Snecma royalties for kaveri upgrades.



1) The larger size would mean redesign of the inside of the Tejas
2) Apart from weight a more powerful engine will consume more fuel. Already 400 kg extra is being taken by engine, so where will extra fuel be acommodated? Or else the LCA's range will be restricted to 200 km

What benefit do you see from fitting AL 31 on Tejas?

PS all bright new ideas should go to the newbie thread, even if it is about LCA

Singha
BRF Oldie
Posts: 66601
Joined: 13 Aug 2004 19:42
Location: the grasshopper lies heavy

Re: LCA News and Discussions

Postby Singha » 11 Jun 2010 08:46

seems to be a delicate dance between engine weight, engine volume, fuel consumption, drag of airframe and fuel tank capacity.

Vikram W
BRFite -Trainee
Posts: 74
Joined: 12 May 2010 02:23

Re: LCA News and Discussions

Postby Vikram W » 11 Jun 2010 08:53

shiv wrote:
Vikram W wrote:So india produces AL 31 engines for the MKIs under deep tech transfer from russia.The engine does about 125 kN in thrust. Why cant we use this engine for apno tejas ? i know its about 400 kilos heavier but shouldnt the 30kN of thurst over the 404 more than compensate ?
and we dont have to pay no Snecma royalties for kaveri upgrades.



1) The larger size would mean redesign of the inside of the Tejas
2) Apart from weight a more powerful engine will consume more fuel. Already 400 kg extra is being taken by engine, so where will extra fuel be acommodated? Or else the LCA's range will be restricted to 200 km

What benefit do you see from fitting AL 31 on Tejas?

PS all bright new ideas should go to the newbie thread, even if it is about LCA

Whats with the attitude Shiv , we are trying to keep the thread lively. The other person has just as much right to voice an opinion as his royal highness. Why would you come at everyone with that condescending tone ?

Austin
BRF Oldie
Posts: 23387
Joined: 23 Jul 2000 11:31

Re: LCA News and Discussions

Postby Austin » 11 Jun 2010 08:55

JMT ... suggestion/correction welcomed

I would prefer some variant ( at least the export ) of Tejas Mk2 should be powered by RD-33Mk ( ~ 90 kn ) . If Tejas has to succeed in external/export market the latter needs an engine which comes with least restrictions and is cost effective.

I would not bet my life on Kaveri powering any variant of Tejas now or in distant future , F-414 or EJ200 will come with strings attached when it comes to exports specifically it will depend on whims and wishes of US or EU.

RD-33MK may not be the best of breed or best in its class but its a fine engine if required with TVC option and it can be made better ( ~10 T class )

Compare this to the fact that some variant of RD-33 is powering the JF-17 and via China it is also in the export market and pushed aggressively.

Dr Kalam has once stated that Tejas has an export potential of ~ 3000 aircraft in global market replacing the Mig-21/23/27 at the same time.

Although right now the focus is rightly more on internal induction of Tejas , its export opportunities should not be a lost cause considering that even Mk1 variant has good potential to replace Mig's

Russia will have no problems in providing its engine or weapons to replace the Mig-21 as they do not have any fighter in that class and its an opportunity to make good money may be using their marketing arm for the same.

It should not be that 10 years from now what could have been Tejas in the cost effective market is the JF-17.

putnanja
BRF Oldie
Posts: 4464
Joined: 26 Mar 2002 12:31
Location: searching for the next al-qaida #3

Re: LCA News and Discussions

Postby putnanja » 11 Jun 2010 08:58

Vikram, this thread is about serious discussions about LCA. All the re-engine discussions have taken place multiple times over the years and may still be in the archives. Those who have been through that don't wish to see the same discussions going on again and again everytime a new member joins the board. Keeping a thread lively is not the primary reason for any thread's existence. It is how much new information and analysis is done on issues affecting LCA

Rahul M
Forum Moderator
Posts: 17016
Joined: 17 Aug 2005 21:09
Location: Skies over BRFATA
Contact:

Re: LCA News and Discussions

Postby Rahul M » 11 Jun 2010 09:16

Vikram W wrote:So india produces AL 31 engines for the MKIs under deep tech transfer from russia.The engine does about 125 kN in thrust. Why cant we use this engine for apno tejas ? i know its about 400 kilos heavier but shouldnt the 30kN of thurst over the 404 more than compensate ?
and we dont have to pay no Snecma royalties for kaveri upgrades.

same reason why we don't fit a tata truck engine in a maruti 800, because it's in a different category. effectively you would need to design a completely new aircraft to accommodate the al-31. compare the dimensions, you will understand,
AL_31 : # Length: 4990 mm
# Diameter: 905 mm inlet; 1280 mm maximum external
F404 : # Length: 154 in (3,912 mm)
# Diameter: 35 in (889 mm)

lastly, please read and follow nukavarapu's post, his advice is excellent. we do expect a higher standard from our members in terms of effort than most internet forums. till you feel up to it, lurk around and post in the newbie thread.
cheers.

Vikram W
BRFite -Trainee
Posts: 74
Joined: 12 May 2010 02:23

Re: LCA News and Discussions

Postby Vikram W » 11 Jun 2010 09:27

Rahul M wrote:
Vikram W wrote:So india produces AL 31 engines for the MKIs under deep tech transfer from russia.The engine does about 125 kN in thrust. Why cant we use this engine for apno tejas ? i know its about 400 kilos heavier but shouldnt the 30kN of thurst over the 404 more than compensate ?
and we dont have to pay no Snecma royalties for kaveri upgrades.

same reason why we don't fit a tata truck engine in a maruti 800, because it's in a different category. effectively you would need to design a completely new aircraft to accommodate the al-31. compare the dimensions, you will understand,
AL_31 : # Length: 4990 mm
# Diameter: 905 mm inlet; 1280 mm maximum external
F404 : # Length: 154 in (3,912 mm)
# Diameter: 35 in (889 mm)

lastly, please read and follow nukavarapu's post, his advice is excellent. we do expect a higher standard from our members in terms of effort than most internet forums. till you feel up to it, lurk around and post in the newbie thread.
cheers.


My hearty thanks for the advice ( i stand wise-nd) and the insights into the size constraints do make more sense.

Indranil
Forum Moderator
Posts: 8172
Joined: 02 Apr 2010 01:21

Re: LCA News and Discussions

Postby Indranil » 11 Jun 2010 10:33

I am sure everybody knows that it is very difficult to change the engine. However to put it into perspective about how difficult it is, I would like to point out a fact.

For most designs an engine is designed first. Based on that choice, the airframe is designed around it. LCA''s case has been quite different.

It is good to discuss what other engine alternatives we have, but please suggest alternatives, which are [b]very[\b] close to the Kaveri, not hundreds of kilos or over 10 cm in diameter. Please don't suggest an engine which is heavier but makes up for its weight by the extra thrust. It is not so easy (as anybody can guess). For starters, think of how you would change the CG and center of thrust.
Last edited by Indranil on 11 Jun 2010 10:37, edited 1 time in total.

Indranil
Forum Moderator
Posts: 8172
Joined: 02 Apr 2010 01:21

Re: LCA News and Discussions

Postby Indranil » 11 Jun 2010 10:34

suraj p wrote:A regional newspaper 'Eenadu' from AP reported that LCA has successfully completed its hot weather trials in its new LSP (4/5) form. It states that Tejas was baked at 45c and later every avionics hardware was tested. The officials were happy. If I am not wrong, LSP(4/5) with MMR, avionics and in weapons configuration will be put into 'Nagpur' test to check for consistency. I am not sure if this reporter is talking about that particular test. If all goes well is next-stop Jaisalmer for weapons test ?

I take 'Eenadu' stories with pinch of salt. However sometimes, it breaks fresh news too. IF this is old news, please ignore!


http://eenadu.net/story.asp?qry1=21&reccount=31


Is LSP-5 flying?!!

Austin
BRF Oldie
Posts: 23387
Joined: 23 Jul 2000 11:31

Re: LCA News and Discussions

Postby Austin » 11 Jun 2010 10:46

nukavarapu wrote:I fail to understand why the IAF Oldies are so discrediting when it comes to LCA ... :(


The criticism or praise from Chief ( past or present ) is because they have the best grip and knowledge on the project development and knows exactly where thing stands from customer prespective and Kiccha is old hand.

Most of the information released by ADA/DRDO would always present the best picture on Tejas much like Lockheed would say best things about its F-22.

Indranil
Forum Moderator
Posts: 8172
Joined: 02 Apr 2010 01:21

Re: LCA News and Discussions

Postby Indranil » 11 Jun 2010 11:13

babbupandey wrote:A question to the gurus, while we are talking of TVC
When TVC is added to an aircraft, while it does add to maneuverability of the aircraft, however, do those maneuvers put some exert some extra stress on the airframe while executing tight turns?
If yes, then is Tejas designed address that?


Please bear with me through this long post. I hope it will be an interesting read.

I will try to find out the thrust vectoring articles again. I read them some years back, so please give me some time to locate them. Actually they are lengthy reads. There was a period of time (almost a decade) where everybody wanted to know whether thrust vectoring will be a game changer. So there were lots of to-and-fro discussions.

But for the crux of the discussion was somewhat captured by a German professor/scientist who proved through simulations that thrust vectoring doesn't add to the maneuverability of a aircraft. But it really lowers the stall speeds for quite a few maneuvers. This is critical for a heavy plane (notice that till now only heavy planes employ TVC). Remember what are the signature moves of the Su-30, Su-35, F-22, all are low speed!

Let me paint you a picture. And this picture is not hypothetical. If you are a reader of DACT exercises, you will find many examples of the same. Suppose you are in a dogfight with a light fighter (say the F-16) and you are ahead. What will you try to do? You would like to turn in any axis where you think you can out turn your opponent who is on a heavier plane behind you. You would like to slow the arena down as much as you can so that the opponent shoots forward and then you can turn in on his tail! On the other hand your opponent with a heavier plane is trying desperately to point his nose inside your turn and ahead of you so that he can have a shot at you. Unfortunately his plane is heavier (assuming slightly asymmetric TWR) . At this slow speed, he can barely maintain this turn rate.

What would he wish for, something which can help him make this slow turn or make his nose point ahead of you or both. And here comes the TVC! It has been proven that just because of this, a heavy plane with TVC might have a flight envelope of a light agile fighter. This is a game changer, something which is enjoyed by the Su-30MKI. Inspite of being a heavy dominance fighter, it is a supreme dog fighter!

But bear in mind, with TVC you can't suddenly turn faster. A plane at such speeds has too much of momentum for the TVC to change the direction of flight. For example none of the thrust vectored planes advertise a faster turning rate because of the vectoring. So you wouldn't suddenly start pulling 10G turns instead of 9Gs! So the airframe doesn't need to change. But what about the engine mount? It has to be made stronger, because when the nozzles are deflected, the engine itself is creating a moment about it's CG. So the mountings will have to be strengthened to bear this load. Hence you would read about the weight gain for TVC engines. It is not just from the mechanism to deflect the nozzles.

I am sorry to have written such a long reply, but I hope I have answered your question satisfactorily. At the same time I would love to learn more or be corrected.
Last edited by Indranil on 11 Jun 2010 11:50, edited 1 time in total.

bhavik
BRFite -Trainee
Posts: 50
Joined: 26 Aug 2009 02:02

Re: LCA News and Discussions

Postby bhavik » 11 Jun 2010 11:20

The criticism or praise from Chief ( past or present ) is because they have the best grip and knowledge on the project development and knows exactly where thing stands from customer prespective and Kiccha is old hand.

Most of the information released by ADA/DRDO would always present the best picture on Tejas much like Lockheed would say best things about its F-22.


But if we believe Lockheed about what it has to say about F22 even without physical evidence.
Why can't we believe ADA when results are verifiable for IAF Test pilots?

Austin
BRF Oldie
Posts: 23387
Joined: 23 Jul 2000 11:31

Re: LCA News and Discussions

Postby Austin » 11 Jun 2010 11:28

bhavik wrote:But if we believe Lockheed about what it has to say about F22 even without physical evidence.Why can't we believe ADA when results are verifiable for IAF Test pilots?


Not every one believes Lockheed and take them at their face value there is considerable documented valid criticism against F-22 out there.

With LCA there are just two parties one is ADA and the other is IAF , so while ADA would like to praise as much about their new bird and they have the right to do so , it is important that we do not miss the good and valid criticism about Tejas when it comes from its end customer the IAF.

bodhi
BRFite -Trainee
Posts: 83
Joined: 02 Dec 2009 09:25

Re: LCA News and Discussions

Postby bodhi » 11 Jun 2010 11:28

indranilroy wrote:
.....


very well written....seems like logical reasoning for the layman

Rahul M
Forum Moderator
Posts: 17016
Joined: 17 Aug 2005 21:09
Location: Skies over BRFATA
Contact:

Re: LCA News and Discussions

Postby Rahul M » 11 Jun 2010 12:52

nukavarapu wrote:I fail to understand why the IAF Oldies are so discrediting when it comes to LCA ... :(
that would too broad a brush. there are many retd senior IAF officers who have good things to say about the project. unfortunately, some of the criticism also tends to stem from their personal experiences. ACM Krishnaswamy for example was responsible for a critical evaluation of the LCA program during his stint at air HQ in the late 80's.

it's a fact of life that the LCA project is at least 3-4 years late from where it should have been at this point. but the responsibility for that does not lie with ADA alone, IAF, MOD all have to share the blame. in fact before ACM Major, the attitude of successive IAF chiefs ranged from mild disdain to overt hostility but never a semblance of cooperation. test pilots were routinely transferred out of the program in the middle of a testing phase hurting the testing schedules because the newer ones had to learn the basics all over again. the situation became so bad once in a flurry of transfers that Wing Co Tarun Bannerjee was once the most experienced of the LCA TP team without having a single flight in the LCA under his belt ! IAF people associated with the program were punished for the association by failing to promote them. AM Rajkumar himself was overlooked for promotions and he got his promotion after a long drawn out fight and then only on the last day of his service.
we also have the callous way in which the wingtip station weight requirements were upped all of sudden smack in the middle of the program, which could easily have been notified to ADA much earlier since it was clear by the mid 90's itself that we were going to shift to the R-73 in the future. the list goes on.
however, I believe the current crop of IAF top brass starting from ACM Major have turned the tide so to speak and now the IAF is fully with the program. criticism from them is much more objective than that of their predecessors.

rohitvats
BR Mainsite Crew
Posts: 7729
Joined: 08 Sep 2005 18:24
Location: Jatland

Re: LCA News and Discussions

Postby rohitvats » 11 Jun 2010 13:27

Rahul da, well put. We need to understand that there is lot of historical baggage which needs to be shed - and which I think is already been shed. As more and more DRDO stuff gets inducted in the IA and that too on time and as per the required specifications -the higher the faith will be amongst the end user. For example - the great work done in case of Dhruv and LCH will translate into higher trust and faith....current crop of officers in junior to mid level would have been exposed to these wonderfull machines and next time DRDO/HAL come up with proposal for meeting a Hptr requirement, there will be that much better response.

Please be advised that I'm in no way absolving the Defence Services of the BBC mentality - but I am seeing that change and over a period of time, we will definitely see a better coordination. One has to only scan the website of the DRDO and it's Labs - I was amazed to see the amount of stuff/items produced by the DRDO Labs which are in IA+IN+IAF Service. It is just that issues with items like Arjun and Akash (in the past) - high visibility capital equipment - tend to hog the limelight while lot of other equally important stuff goes unnoticed.

Gagan
BRF Oldie
Posts: 11209
Joined: 16 Apr 2008 22:25

Re: LCA News and Discussions

Postby Gagan » 11 Jun 2010 13:38

indranilroy wrote:Let me paint you a picture. And this picture is not hypothetical.
:!: Very well written
Thanks.

Austin
BRF Oldie
Posts: 23387
Joined: 23 Jul 2000 11:31

Re: LCA News and Discussions

Postby Austin » 11 Jun 2010 14:31

Ok Pardon my ignorance.

But from what I have read TVC in simple word is maneuverability at stall speed , it means it gives any aircraft the ability to point its noise in any direction(AOA) it wants without going into a spin or just falling down ( call it controlled maneuverability at very low speed )

It achieves the same at the loss of altitude and speed which means energy ( critics argue that energy is every thing hence no point loosing it at cost of super-manouveribility )

So I am really not convinced with the argument that heavy agile fighter needs TVC to fight while the light agile one can simply do without it. ( IMO agility of light fighter has nothing to do with TVC )

If you need your light fighter to achive super-maneuverability( a PR term ) at stall speed you need to compensate it by TVC of its engine , without that it does not matter if that fighter is agile light or heavy

The other advantage of TVC i remember we discussed at BR was that the aircraft needs less trim while in flight due to TVC which helps in management of fuel.

There is an advantage in BVR combat but that is something no one has spoken and discussed yet.

The reason why you see TVC in heavy ( or just US and Russia ) is because no other country has invested money, time and Technology Demo aircraft on this technology to mature except for those two.

Bala Vignesh
BRF Oldie
Posts: 2017
Joined: 30 Apr 2009 02:02
Location: Standing at the edge of the cliff
Contact:

Re: LCA News and Discussions

Postby Bala Vignesh » 11 Jun 2010 14:41

Indranil Sir, the article you are quoting ( or something close to it ) is availble on the Mil Aviation Thread.. Posted By Andy B sir a few months back... It was a good read..


Return to “Trash Can Archive”

Who is online

Users browsing this forum: No registered users and 18 guests