ADA Tejas (LCA) News and Discussions

[rahulrds1]

AeroMag

http://www.nal.res.in/pdf/AM 1- 2013.pdf

 

[ersakthivel]

 

[arunpat]

Tejas at Aero India 2013 - Tejas - India's Light Combat Aircraft

 

[rahulrds1]

R Sundar , CEO, Aerospace Engineers in a Interview with AeroMag magazine about Kaveri Engine.

Q:What's the latest on the Kaveri engine? GTRE's association with LCA Tejas programme?

A :Kaveri engine prototype was integrated with IL-76 aircraft at Gromov Flight Research Institute (GFRI), Russia and flight tests have been successfully carried out. Issues required to be addressed have been identified and are being addressed and it is planned to commence flight trials for technology demonstration of Kaveri engine with LCA Tejas Mk-I in about three years
time.


GTRE has so far developed 9 prototypes of Kaveri engines and 4 prototypes of Kabini (Core) engines. The engines have run cumulatively for over 2200 hours at ground and altitude conditions for various requirements including performance, operability, endurance, environmental etc. Further endurance testing is under progress at GTRE. Two major milestones
achieved viz. successful completion of Official Altitude Testing (OAT) and completion of first block of flights of Kaveri engine in Flying Test Bed (FTB) have demonstrated the technological capability and maturing of the indigenous efforts.



Page No. 47 from the pdf by NAL(national aerospace laboratories)
http://www.nal.res.in/pdf/AM 1- 2013.pdf

Further in the magazine It is mentioned that.

LCA will be tested for Angle of Attack more than 22 and maneuvering greater than 6 g.

 

[p2prada]

Re: HAL gears up for first flight of Tejas LSP-8 and LCA series produc

40 aircraft in 5 years. That is 8 / year, with two aircraft to be delivered this year. Which would mean the FOC squadron will be functional in the 2018-19 period.

The LCA line would free up for LCA Mk2 by then. So, IOC of Mk2 would be around 2019-20.

 

[Twinblade]

 

[Kunal Biswas]

Tejas

 

[ersakthivel]

 

[arunpat]

LCA-Tejas has completed 2061 Test Flights Successfully. (28-Feb-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-351,LSP1-74,LSP2-257,PV5-36,LSP3-105,LSP4-66,LSP5-139,LSP7-27,NP1-4)

to

LCA-Tejas has completed 2068 Test Flights Successfully. (04-Mar-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-351,LSP1-74,LSP2-257,PV5-36,LSP3-107,LSP4-67,LSP5-142,LSP7-27,NP1-4)

 

[ersakthivel]

 

[ersakthivel]

 

[ersakthivel]

 

[ersakthivel]

http://htmlimg4.scribdassets.com/4j4n20w741cgyiu/images/4-9b8c39d0f3.png

The above link was posted by kunal biswas in his earlier post.

Tejas wing consists of a pure double delta configuration with leading edge angles of 50degree and62.50 degreeand a trailing edge forward sweep angle of 4 degree.

The CG lies about 33.5% of MACand the wing area is 38.5 m.

Wind tunnel experiments haveindicated that CL max continues to improve till approx 35 degree,AoA as shown at figure in PDF in the above link.

However, directional characteristics indicated the proverbial 'cliff' with a sudden drop in, CRM (Coefficient of Rolling Moment) and CYM (Coefficient of Yawing Moment) atapprox 25 degree AoA .

These phenomena require the High AoA trialsto be limited to 24 degree until directional stability is bolstered and augmented by rudder control up to an expected 26 degree .

Currently the Tejas is flying to AoAlimits of 20 degree and 22 degree never exceed. Fortunately , the LCA has significant rudder authority (CYM-Del R) even up to 30 degree AoA that will allow artificialstabilization in yaw at high AoA

So a normal AOA expected is to be 24 degrees for TEJAS,
It can go up to 26 degree , if directional stability is bolstered and augmented by rudder control,
LCA has significant rudder authority, so even up to 30 degree AoA that will allow artificialstabilization in yaw at high AoA,

Considering it's low wing loading and high TWR of 1.07 , the str will be as comparable to modern 4.5th gen deltas, if full flight envelope is opened up after departure prevention testing is completed as shown in the PDF in the link mentioned above,

Sustained turning rate (str)depends on three factors
1.thrust to weigth ratio,
2.AOA ,
3.wingloading,
Tejas can have a FCS limited 24 to 26 deg AOA , which is close to most 4.5th gen fighters,

It's Thrust to weight ratio is 1.07 in mk-1 and will be closer to 4.5th gen fighters like RAFALE in mk-2 version(since higher thrust engine is expected , and IAF version will have no significant weight increase because there is no need to strengthen the landing gear as that of the naval version)

It's wing loading is the lowest for any fighter in the world,

So a comparable sustained turn rate and good instantaneosu turn rate will be there for TEJAS as per the info in the above link.

 

[ersakthivel]

Angle of Attack(AoA)

It is the maximum angle an aircraft makes against the air flow. Practically it means, the greater the angle of attack, the more vigoursly you can turn. This is important in close combat because the more the angel of attack, the more tighter the pilot can turn. So aircrafts having high AoA wiill have smaller turn radius.

If an aircraft exceeds its Angel of attack , then it loses its aerodynamic grip on the air. That is the pressure above the wing is no longer lower the pressure below the wing. and becomes a stone in the sky falling towards the earth.


Thrust to Weight ratoi(TWR)

TWR is obtained by dividing the Engine-thrust of a fighter by its weight. If the Thurst is more than its weight then TWR is greater than 1. If thrust is less than the weight ,then TWR is less than 1. So fighters with TWR more than 1 can zoom up into the sky like a rocket instead of gradually increasing their altitude.

Also having more thrust to weight ratio means, the fighter can use the maximum use of its angle of attack. It wont matter if your fighter has a high AoA but a poor thrust to weight, because your fighter at maximum high AoA creates more drag and slows down the fighter. The more you turn with the help of high AoA, the more you loose speed.

The only way to counteract this lose of speed, is for the engine to put out more power. More engine power(or in other words more thrust to weight ratio) means, more thrust to counteract the drag due to high AoA turn. Say both Fighter-A & Fighter-B have an angle of attack of 25 degrees, but A has TWR of 1.2 while B has a TWR of 1.1.

Since A has more engine power than B, it will turn more tightly than B because the more engine thrust will counteract the slow down due to a high AoA turn.

So eventhough both B and A has 25 degrees of AoA, B won't be able to fully utilise its 25 degrees to match A's turn as it will create extra drag which cannot be counteracted by its engine thrust and will start to lose speed and become a sitting duck soon. While Fighter-A will turn tighter because the drag will be counteracted by its superior TWR(or more engine thrust).


Sustained Turn Rate(STR)

STR as the name implies is a turn which can be sustained. STR is a derived quantity from AoA and TWR. As explained above, the balance between AoA and TWR makes Fighter B to turn at 22 degrees AoA only because if it goes abve that, it will start to lose speed. At 22 degrees AoA and TWR of 1.1, lets assume Fighter B can complete a full circle 360 degree turn in 20 seconds, without losing air speed. So its sustained turn rate is, 360 degrees divided by 20 sec, which is 18 degrees per second. So the STR of Fighter B is 18 degrees per second. While Fighter A with 24 degrees AoA and TWR of 1.2, will complete a full 360 turn much faster than Fighter B. Lets assume it completes it in just 16 seconds. So its STR is 360/16 = 22.5 degrees per second.

What this means is, if both fighter A and Fighter B meet each other head-on in a turning fight and start turning(it is called a merge), (the initial difference in angle in a head on engagement is 180 degrees.), Fighter A due to its superior STR(it has a superior STR because of a superior AoA, and it got its superior AoA because of its superior TWR. Now you can see how these parameters interact with each other.), will slowly start to get behind Fighter-B.

Fighter-A has an advantage of 4.5 degres per second(22.5-18), over B. So to cover 180 degrees(or get behind B's back), Fighter-A will take 40 seconds to do it(180/4.5). So after A and B meet face to face, Fighter A will be behind Fighter B in just 40 seconds and pump his asss full of lead with his cannon or missile. This is what STR is all about.

Instantaneous Turn Rate(ITR)

ITR , is a turn which is performed instantaneously. Here the full 25 degrees AoA is used by both fighters A and B. As a result, both A and B whose STR limits them to 24 and 22 degrees respectively, doesn't matter here. Ofcourse turning at 25 degrees AoA creates massive drag, which slows down both the fighters, with B slowing down much more than A.

So you can ask, why on earth would a fighter turn like that, lose speed and become a sitting duck? A few years ago that would have been true, but with the new short range high off boresight missiles, all u have to do now is to turn using your full AoA advantage and quickly point your nose to the direction of the enemy fighter, get a lock on, with your missile, and then fire!

So you can turn instantly, move your nose in the general direction of the enemy, get a lock on your HMS, get a good tone on your Short range off-bore sight missile, and launch it.

With off bore-sight missiles, this becomes even more easier since you don't have to fully turn and only come into the off bore of the missile in order to launch. So when on a headon engagement(180 degrees difference), Fighter-A with 90 degrees high off boresight missiles and HMS, coupled with thrust vectoring, will perform a much higher ITR, and as a result will turn faster and will be able to get a lock-on much faster than Fighter-B (with its own 90 degrees high off boresight missile and HMS).

 

[rahulrds1]

What is " Angle of Attack " (AoA)




Forces that Act on Aircraft in flight

 

[Decklander]

Angle of Attack(AoA)

It is the maximum angle an aircraft makes against the air flow. Practically it means, the greater the angle of attack, the more vigoursly you can turn. This is important in close combat because the more the angel of attack, the more tighter the pilot can turn. So aircrafts having high AoA wiill have smaller turn radius.

If an aircraft exceeds its Angel of attack , then it loses its aerodynamic grip on the air. That is the pressure above the wing is no longer lower the pressure below the wing. and becomes a stone in the sky falling towards the earth.


Thrust to Weight ratoi(TWR)

TWR is obtained by dividing the Engine-thrust of a fighter by its weight. If the Thurst is more than its weight then TWR is greater than 1. If thrust is less than the weight ,then TWR is less than 1. So fighters with TWR more than 1 can zoom up into the sky like a rocket instead of gradually increasing their altitude.

Also having more thrust to weight ratio means, the fighter can use the maximum use of its angle of attack. It wont matter if your fighter has a high AoA but a poor thrust to weight, because your fighter at maximum high AoA creates more drag and slows down the fighter. The more you turn with the help of high AoA, the more you loose speed.

The only way to counteract this lose of speed, is for the engine to put out more power. More engine power(or in other words more thrust to weight ratio) means, more thrust to counteract the drag due to high AoA turn. Say both Fighter-A & Fighter-B have an angle of attack of 25 degrees, but A has TWR of 1.2 while B has a TWR of 1.1.

Since A has more engine power than B, it will turn more tightly than B because the more engine thrust will counteract the slow down due to a high AoA turn.

So eventhough both B and A has 25 degrees of AoA, B won't be able to fully utilise its 25 degrees to match A's turn as it will create extra drag which cannot be counteracted by its engine thrust and will start to lose speed and become a sitting duck soon. While Fighter-A will turn tighter because the drag will be counteracted by its superior TWR(or more engine thrust).


Sustained Turn Rate(STR)

STR as the name implies is a turn which can be sustained. STR is a derived quantity from AoA and TWR. As explained above, the balance between AoA and TWR makes Fighter B to turn at 22 degrees AoA only because if it goes abve that, it will start to lose speed. At 22 degrees AoA and TWR of 1.1, lets assume Fighter B can complete a full circle 360 degree turn in 20 seconds, without losing air speed. So its sustained turn rate is, 360 degrees divided by 20 sec, which is 18 degrees per second. So the STR of Fighter B is 18 degrees per second. While Fighter A with 24 degrees AoA and TWR of 1.2, will complete a full 360 turn much faster than Fighter B. Lets assume it completes it in just 16 seconds. So its STR is 360/16 = 22.5 degrees per second.

What this means is, if both fighter A and Fighter B meet each other head-on in a turning fight and start turning(it is called a merge), (the initial difference in angle in a head on engagement is 180 degrees.), Fighter A due to its superior STR(it has a superior STR because of a superior AoA, and it got its superior AoA because of its superior TWR. Now you can see how these parameters interact with each other.), will slowly start to get behind Fighter-B.

Fighter-A has an advantage of 4.5 degres per second(22.5-18), over B. So to cover 180 degrees(or get behind B's back), Fighter-A will take 40 seconds to do it(180/4.5). So after A and B meet face to face, Fighter A will be behind Fighter B in just 40 seconds and pump his asss full of lead with his cannon or missile. This is what STR is all about.

Instantaneous Turn Rate(ITR)

ITR , is a turn which is performed instantaneously. Here the full 25 degrees AoA is used by both fighters A and B. As a result, both A and B whose STR limits them to 24 and 22 degrees respectively, doesn't matter here. Ofcourse turning at 25 degrees AoA creates massive drag, which slows down both the fighters, with B slowing down much more than A.

So you can ask, why on earth would a fighter turn like that, lose speed and become a sitting duck? A few years ago that would have been true, but with the new short range high off boresight missiles, all u have to do now is to turn using your full AoA advantage and quickly point your nose to the direction of the enemy fighter, get a lock on, with your missile, and then fire!

So you can turn instantly, move your nose in the general direction of the enemy, get a lock on your HMS, get a good tone on your Short range off-bore sight missile, and launch it.

With off bore-sight missiles, this becomes even more easier since you don't have to fully turn and only come into the off bore of the missile in order to launch. So when on a headon engagement(180 degrees difference), Fighter-A with 90 degrees high off boresight missiles and HMS, coupled with thrust vectoring, will perform a much higher ITR, and as a result will turn faster and will be able to get a lock-on much faster than Fighter-B (with its own 90 degrees high off boresight missile and HMS).

In this age of all aspect missiles and no escape zones using missiles guided by HMD, STR & ITR have very little role to play. BVR launches are done at nearly 1G with zero role rate. In a headon cross, R-73 has shown ability to be fired when opposition fighter is still in the forward sector and the missile being steered by HMD to turn nearly 120* to hit the target just when it crosses you again with zero roll rate. R-73 uses proportional navigation to hit its target. It is fired when the enemy is still in the fwd sector and than its seeker is help by HMD to look in a particular area by the pilot firing it. It locks on and turns even 150* to chase the target. Python-5 can be fired to hit targets behind you. The famous Pughachev Cobra is a way of firing missiles in an over the shoulder toss method to shoot down enemy aircraft who are behind you or chasing you. You give a Mig-29 or Su-30MKI just 500 meters around you in any plane, and he will be on your tail.

 

[p2prada]

In this age of all aspect missiles and no escape zones using missiles guided by HMD, STR & ITR have very little role to play. BVR launches are done at nearly 1G with zero role rate. In a headon cross, R-73 has shown ability to be fired when opposition fighter is still in the forward sector and the missile being steered by HMD to turn nearly 120* to hit the target just when it crosses you again with zero roll rate. R-73 uses proportional navigation to hit its target. It is fired when the enemy is still in the fwd sector and than its seeker is help by HMD to look in a particular area by the pilot firing it. It locks on and turns even 150* to chase the target. Python-5 can be fired to hit targets behind you. The famous Pughachev Cobra is a way of firing missiles in an over the shoulder toss method to shoot down enemy aircraft who are behind you or chasing you. You give a Mig-29 or Su-30MKI just 500 meters around you in any plane, and he will be on your tail.

India ordered 100 Python IV in 2005 for the IAF and 750 Python V for the SPYDER SAM.

Any idea why this missile wasn't chosen for the LCA program? Or will R-73 be the mainstay of the LCA Mk1 while the LCA Mk2 will get the Python V, or a VI. Perhaps that will answer the question on why the Python V model was in front of the LCA in AI-13.

 

[Decklander]

India ordered 100 Python IV in 2005 for the IAF and 750 Python V for the SPYDER SAM.

Any idea why this missile wasn't chosen for the LCA program? Or will R-73 be the mainstay of the LCA Mk1 while the LCA Mk2 will get the Python V, or a VI. Perhaps that will answer the question on why the Python V model was in front of the LCA in AI-13.

Python-5 and MICA have FPA tech. AIM-9x and beyond are likely to have that. R-73/R74M do not have FPA yet. FPA allows you to have outstanding ECCM as the IR seeker locks on to a plan form which generates IR in low band of 3-5meu which is the frequency at which skin of an aircraft radiates and FPA makes a picture of such a target and so the IR flares are rendered ineffective as they do not have IR radiation in that band and have no IR pix of an aircraft size.

Russians are trying to build one such FPA IR seeker but they are far behind the latest QWIP seekers which are now part of Python-5 and will soon be available in Europe. As of now GaN based QWIP is known only to USA & Israel.

 

[Twinblade]

India ordered 100 Python IV in 2005 for the IAF and 750 Python V for the SPYDER SAM.

Any idea why this missile wasn't chosen for the LCA program? Or will R-73 be the mainstay of the LCA Mk1 while the LCA Mk2 will get the Python V, or a VI. Perhaps that will answer the question on why the Python V model was in front of the LCA in AI-13.

It has already been officially displayed at the weapon to be integrated on Tejas.

 

[p2prada]

Python-5 and MICA have FPA tech. AIM-9x and beyond are likely to have that. R-73/R74M do not have FPA yet. FPA allows you to have outstanding ECCM as the IR seeker locks on to a plan form which generates IR in low band of 3-5meu which is the frequency at which skin of an aircraft radiates and FPA makes a picture of such a target and so the IR flares are rendered ineffective as they do not have IR radiation in that band and have no IR pix of an aircraft size.

Russians are trying to build one such FPA IR seeker but they are far behind the latest QWIP seekers which are now part of Python-5 and will soon be available in Europe. As of now GaN based QWIP is known only to USA & Israel.

I agree.

A dual MMW and QWIP seeker head will make way for next generation of missiles. (Just my wish )

But is there a reason why it has not been opted for the LCA program as a whole? Meaning there are better missiles out there, even the RVV-MD is better than the R-73. But according to the navy officer, LCA will have only the R-73. I always thought the R-73 was an interim measure. As a matter of fact, I thought we would go in for Aim-132s or any of the other options being planned for Jaguar.

Anyway, an image using a FPA on the Aim-9x.

It has already been officially displayed at the weapon to be integrated on Tejas.

I know that. But what I don't know is why that officer who spoke to Karthik (or was it someone else) from BR said that R-73 will be the standard missile on LCA.

Or was he just referring to LCA Mk1 and not MK2?