LCA News and Discussions

NRao · Post by **NRao** » 16 Jan 2011 05:41

In fact here (thanks to google chacha) seems to be the same air craft at take off. And Broadsword, in fact, mentions a camera pod. You can expand that picture to get a better idea.

But, for sure, all those bombs are rigged for testing and not practice. Those round things with black-white quadrants are used to see what happens at the time of separation from the air craft - during a first time test drop.

SaiK · Post by **SaiK** » 16 Jan 2011 05:44

N Rao, if you are talking about this pic: http://www.bharat-rakshak.com/IAF/Image ... -Bombs.jpg, then shiv is right is my understanding.

NRao · Post by **NRao** » 16 Jan 2011 05:49

SaiK wrote:N Rao, if you are talking about this pic: http://www.bharat-rakshak.com/IAF/Image ... -Bombs.jpg, then shiv is right is my understanding.

I still do not thing so.

here is the very same air craft, and as I said, Broadsword has it marked as a camera pod.

Besides, in both the pictures, the bombs to be dropped are marked with those round things used only during testing the first few drops - as I said for figuring out what happens during a separation.

I cannot make out the KH number on the Broadsword web site, but that is the very same config of what is posted from BR web site.

added l8r:

these three are the very same air craft, first is pre-flight, second I thing is during rollout, third obviously is flight:

first
second
third

Added much l8r:

Found more info:

The Light Combat Aircraft tests its teeth: a ringside account of an LCA bombing run

SaiK · Post by **SaiK** » 16 Jan 2011 05:53

^^The one on the right most is the one we are talking right? If it is so, then it just different views aage, peeche on the same thing. It is a cluster bomb pack. Now, if the red lobe carries a hidden camera, then I may be wrong.

SaiK · Post by **SaiK** » 16 Jan 2011 05:56

mmm hang on.. you may be right.. sorry/ I do see the two red angled cameras

NRao · Post by **NRao** » 16 Jan 2011 05:57

The green one is carrying the "cluster bombs" (if that is what it is).

However, in any of them the red pod is a camera pod. In all cases they are skewed to face what they are photographing (at real high speeds).

Maan gaye. HAL/ADA/etc have really brought some thing to the table. I, for one, am a lot more convinced about the outcome of the AMCA now then ever before.

shiv · Post by **shiv** » 16 Jan 2011 06:29

OK - It is possible that the "red/green thing" is a generic holder for all sorts of stuff, including cameras in this case. I don't think cluster bombs look like that green thing. Those are practice bombs that appear on a whole lot of other photos. I think I have a cluster bomb video somewhere - need to locate it.

shiv · Post by **shiv** » 16 Jan 2011 06:49

NRao wrote:We never had a single failure so far in 1,500 flights of Tejas: ADE

A very good article.

I think this article, whose original url is below should be linked from the fist post of every LCA/Tejas thread.

I also believe that the article explains something that we need to adjust our minds to accommodate. The "LCA" was the concept of a Light Combat Aircraft which someone dreamed of in 1983. The development of what we have today, the Tejas HF-xx started in 1993.

There is a difference. If a boy dreams of learning how to fly at age 5, but finally gets a chance to join flying school at age 45 and gets his licence within one year it does not mean that he took 40 years to learn flying and get a pilot's licence.

Also - can we have a change of name of this thread to Tejas (LCA) thread or something like that?

Indranil · Post by **Indranil** » 16 Jan 2011 06:54

NRao wrote:The green one is carrying the "cluster bombs" (if that is what it is).

They are 25 pound practice bombs in Carrier Bomb Light Stores Mk200-1A.

SaiK · Post by **SaiK** » 16 Jan 2011 06:56

Yes.. indeed.. especially this one would make any one feel how important it is to be independent from all kinds of invasions.

Then there were the sanctions after Pokhran II. How did that affect the development of Tejas?

Let me be clear — we perhaps got delayed by two years. On the day the sanctions came into force, our team was in the US offices of our partners there (Lockheed Martin and BAE Inc.). The team was working on integration of software with the hardware of the LCA. Suddenly we were asked to leave the offices, and we were not even allowed to take back the designs we were working on the systems there, and those were almost ready to be tested. We had to again develop it from memory, because we weren’t allowed to copy our own stuff, which delayed the whole thing.

---

PS: coming to think of it, there is a software management catch here - never leave home without a backup done.

suryag · Post by **suryag** » 16 Jan 2011 07:01

^^^ this happened to me once(on a smaller scale though) when i ended up deleting a file containing close to 50k lines of code. It was tested and raring to go, however, when i rewrote it(took a month or so) i think it performed better than the previous version may be because i had the liberty to improve the design which i wouldnt have done had the older code been there due to inertia

Jagan · Post by **Jagan** » 16 Jan 2011 07:04

The Red thing can be seen here - maybe its a smaller size bomb carrier for the 3KG practice bombs? Or some sort of universal carrier..

One thing about the above thumbnail is the ac is assymetrically loaded - Carrier-Empty-Empty-Fuselage-Empty-Bomb-Missile

maybe just dropped a bomb or something?.

SaiK · Post by **SaiK** » 16 Jan 2011 07:06

suryag, version control systems with backup/restore setup is a must.

Thomas Kolarek · Post by **Thomas Kolarek** » 16 Jan 2011 07:09

Tejas is very huge achievement for India definitely, the learning cycle is costlier and we should learn to not repeat this in any of our future programs. We never had shortage of talented Scientists & Engineers. LCA team should hire an team of high end marketing consultants to better manage media & its customers. Its too vague to ask Engineers & Scientists to manage the marketing part.

shiv · Post by **shiv** » 16 Jan 2011 07:09

Jagan wrote:

The Red thing can be seen here - maybe its a smaller size bomb carrier for the 3KG practice bombs? Or some sort of universal carrier..

One thing about the above thumbnail is the ac is assymetrically loaded - Carrier-Empty-Empty-Fuselage-Empty-Bomb-Missile

maybe just dropped a bomb or something?.

Jagan - that may be the one being dropped here?

Indranil · Post by **Indranil** » 16 Jan 2011 07:17

suryag wrote:^^^ this happened to me once(on a smaller scale though) when i ended up deleting a file containing close to 50k lines of code. It was tested and raring to go, however, when i rewrote it(took a month or so) i think it performed better than the previous version may be because i had the liberty to improve the design which i wouldnt have done had the older code been there due to inertia

<completely OT ALERT>
You wrote 50K lines of code in 1 month!!! Take a bow.

NRao · Post by **NRao** » 16 Jan 2011 07:48

http://2.bp.blogspot.com/_o_no4M2xEPY/T ... 709941.JPG

The URL should say it all - this LCA has nothing but the camera pod. LiveFist too has a set of pictures of the same air craft (as does BroadSword), but different angles.

That red thing is a camera pod. One can see the wires from the camera at the end of the camera too (in the calender).

indranilroy wrote:
suryag wrote:^^^ this happened to me once(on a smaller scale though) when i ended up deleting a file containing close to 50k lines of code. It was tested and raring to go, however, when i rewrote it(took a month or so) i think it performed better than the previous version may be because i had the liberty to improve the design which i wouldnt have done had the older code been there due to inertia
<completely OT ALERT>
You wrote 50K lines of code in 1 month!!! Take a bow.

Is backups a forgotten art?

Kanson · Post by **Kanson** » 16 Jan 2011 08:00

It is not a universal carrier. It is as noted a camera pod.

shiv · Post by **shiv** » 16 Jan 2011 08:11

Kanson wrote:It is not a universal carrier. It is as noted a camera pod.

Agreed and accepted.

suryag · Post by **suryag** » 16 Jan 2011 08:21

The code that was lost was when i was in one of "our labs" in 2002 We were starting out on a new project and didnt have all the version controlling setup.

When are spin recovery tests scheduled for the Tejas. Can Spin recovery be tested in the wind tunnel ?

vina · Post by **vina** » 16 Jan 2011 08:46

The last scan posted by shiv shows G limits as 8.5/-3.5. So has the max G been revised downwards from 9 to 8 now?

Hmm. Interesting question. Shiv's scan from the calendar titled "Ground Testing" says that the airframe has been tested and certified for 8g/-3.5g and a ultimate max of 1.5 times operating load.

Now it can mean a lot of things. Is the airframe capable of more, like say 9g , but has been limited to 8g for now (like the F-18s) for whatever reasons (like maybe tested only until that limit for now , more confidence needed with fatigue life , which can be got back from in service feedback ), I think yes , but the airframe definitely can pull more G . So is the 1.5 times "operating loads", 12g ? I would think yes, and that looks like is the ultimate load limit of the Tejas.

suryag · Post by **suryag** » 16 Jan 2011 09:36

ADA's website is down since yesterday, hope they are coming up with a new one

Raja Bose · Post by **Raja Bose** » 16 Jan 2011 10:09

Thomas Kolarek wrote:Tejas is very huge achievement for India definitely, the learning cycle is costlier and we should learn to not repeat this in any of our future programs. We never had shortage of talented Scientists & Engineers. LCA team should hire an team of high end marketing consultants to better manage media & its customers. Its too vague to ask Engineers & Scientists to manage the marketing part.

It is always costly and mistakes/falls are the only way to learn how to do things right (same as learning to ride a bicycle). I agree about the marketing part - that is traditionally a weak point for us SDREs.

Vivek K · Post by **Vivek K** » 16 Jan 2011 10:10

12G! Wow! Go LCA!!!

Kartik · Post by **Kartik** » 16 Jan 2011 11:40

vina wrote:
The last scan posted by shiv shows G limits as 8.5/-3.5. So has the max G been revised downwards from 9 to 8 now?
Hmm. Interesting question. Shiv's scan from the calendar titled "Ground Testing" says that the airframe has been tested and certified for 8g/-3.5g and a ultimate max of 1.5 times operating load.

Now it can mean a lot of things. Is the airframe capable of more, like say 9g , but has been limited to 8g for now (like the F-18s) for whatever reasons (like maybe tested only until that limit for now , more confidence needed with fatigue life , which can be got back from in service feedback ), I think yes , but the airframe definitely can pull more G . So is the 1.5 times "operating loads", 12g ? I would think yes, and that looks like is the ultimate load limit of the Tejas.

Vina, it means that the airframe was designed to not just 12G ultimate loads-rather 1.5 times of 9Gs limit load, so that's 13.5Gs ultimate loads. There was a discussion on this earlier too.

The problem appears to be that because the airframe itself turned out heavier than when the original loads to which it was designed for, it cannot reach that now with fuel and air to air weapons.

The FBW FCS are g-demand at medium to higher speeds- so the pilot maneuvers and the FCS allows him to pull Gs during these maneuvers as per the weight of the aircraft, which is constantly monitored as fuel gets used up.

It will limit the Gs that the pilot can pull so as to not overstress the airframe and wings. No fighter that has full internal fuel will likely allow the pilot to pull 9Gs - but progressively, as the internal fuel starts getting used up, the weight of the fighter goes down and the pilot can demand more Gs from the FCS. At lower speeds, the FCS will no more be g-demand but rather alpha-demand, where alpha (AoA) will be controlled and FCS will not allow the pilot to exceed the limits set so as to not stall.

So, when the airframe was supposed to be 5.5 tons empty, with fuel of 2.5 tons and another 0.5 tons for other equipment, pilot, etc. and 2 A2A missiles and pylons weighing another 0.5 tons, the total weight would be 9 tons. As more and more fuel got used up, the FCS would allow the pilot to eventually reach 9Gs at some point (some weight, say X). And the airframe would be stressed to allow it to pull 9Gs at that weight limit (maybe 5.5 tons+ 1 ton fuel + 1 ton other items = 7.5 tons)

But, since the airframe ended up being 1 ton over the initial design goal, that means that at the point at which 9Gs could have theoretically been reached earlier (X), the weight is actually now X + 1000 kgs- that means the FCS will not allow it to pull 9Gs at that point since its 1000 kgs over what it should be. Now how do you get to 7.5 tons ? 6.5 tons is the weight of the airframe, 1 ton is the weight of other items, so there is no allowance for fuel at all.

For it to now reach the point where 9Gs can be pulled, the fuel on board will have to be 1000 kgs less since that is the only thing that is getting expended in air during the sortie. Doing 9Gs on a clean aircraft is useless as far as operational service goes, so then, whatever is the operationally useful G load that can be attained is the one that it will be certified to during FOC.

Either airframe weight has to be brought down by 1000 kgs or the fuel has to be lesser by 1000 kgs to now make it reach 9Gs at that point X. On the Tejas Mk2, if they successfully bring down the weight by that much, the G limit will go up.

You can see how this works on a Gripen as explained by Chris Yeo, during his excellent summary of his flight test on a Gripen B

At this stage, the fuel remaining had decreased to 105% of internal fuel. At take-off mass, the aircraft was limited to
5g by the full external fuel tank. As the tank emptied below 200kg, the g-limit started to increase progressively to a maximum of 7.5g of the FCS standard tested. The two-seater's limit will be increased to 8.5g in the near future. As
the gun tracking exercise began the g-limit was ~g. The g and incidence limits are regulated automatically by the FCS.

Flight Global link

akimalik · Post by **akimalik** » 16 Jan 2011 11:53

Remote Ejection Trigger...
Hi all, I had a small query:
Does the LCA have some form of remote trigger to the activate the ejection mechanism?
I mean to ask this from the point of view of the upcoming Wake Separation tests etc when the LCA will be deliberately put into situations where it be expected to loose control. In such a scenario, due to some unforeseen reason if the pilot is unable to effect the ejection, can the same be triggered from the test-center once they realize that the pilot is unable to initiate the ejection sequence?
TIA

suryag · Post by **suryag** » 16 Jan 2011 13:58

found this on lca spin recovery I think we all read this earlier

RECOVERY PARACHUTE SYSTEM FOR LIGHT COMBAT AIRCRAFT

It is mandatory for a combat aircraft to demonstrate its spin recovery capability during flight test programme. The purpose of this system is to provide emergency recovery of aircraft from an inadvertent spin in case the aircraft controls are ineffective and are unable to pull it out of spin.

The recovery is achieved by deployment of a parachute, which applies an anti-moment force at the rear of the out of control aircraft bringing its nose down further. This brings the aircraft into a controlled stabilized dive and helps it to come out of spin/deep stall.

DRDO has developed such parachutes for the flight test of LCA. The test altitude envelope for LCA (9500 kg weight) is 2 km to 12 km. The sequence of operation is as follows:

When a drogue gun is fired, the slug mass of the drogue gun moves rearwards and sequentially deploys the pilot chute at an aircraft wake distance of 23 m. When the pilot chute is stretched, snapping of the weak tie (48 kg) separates the slug mass of the drogue gun along with deployment bag of pilot chute. The chute then inflates and consequently pulls the packed main parachute.

As the pilot chute moves rearwards the main parachute deploys sequentially. As soon as the main parachute is stretched, snapping of the weak tie (100 kg) separates the pilot chute and the deployment bag of main parachute. This allows the main parachute to inflate and produce necessary drag force of 32 kN, resulting in a yawing movement of aircraft.

It then steepens the flight path angle (a-angle) of the aircraft. The aircraft can then be pulled out of spin by increasing its speed. The total operational time of the system is 3 s. When the aircraft comes out of spin, pilot jettisons the parachute by operating the release mechanism.

The system has various redundancy/safety devices. When the release system fails, parachute can be separated through failure of weak link by accelerating the aircraft by 30 per cent.
Development work at sub-system level has been successfully completed and final qualification tests are under progress.

kit · Post by **kit** » 16 Jan 2011 14:00

The Tejas is touted as a fly-by-wire system; that is, one that uses sophisticated computer electronics to make it as foolproof as possible. A fly-by-wire aircraft normally has four circuits for each connection, meaning even if one circuit to the landing gear fails, three others will still operate. But in reality, the Indian Tejas has only two such circuits, not four. Technically it does not qualify as a fly-by-wire aircraft. And guess what India is handling in the fifth-generation fighter project it is planning with Russia—the fly-by-wire system.

http://www.openthemagazine.com/article/ ... sible-bird

??!

uddu · Post by **uddu** » 16 Jan 2011 14:17

Will 4 enough for the Chinese or a minimum of 8 is required to safely land?

PratikDas · Post by **PratikDas** » 16 Jan 2011 15:56

Kit, firstly, the claim that there are only two circuits is false:
Tarmak007: Surviving Sanctions only to become World-Beaters: Tracking the fly-by-wire FCS story from ADE (Part-III-A), 9 January 2011

Some of the highlights of the Onboard Software are Kernel working in real time, synchronization of the 4 identical computers, managing the redundancy to ensure accurate inputs for the Control Laws and the right drive to the actuators, software-controlled Built-In-Test for ensuring the health of the system before each flight.

Secondly, it seems like the authors of the Open The Orifice sorry, Magazine, article don't know what a fly-by-wire system is. Even if there is one and only one circuit handling all flight operations electronically, the system is still fly-by-wire.

Finally, you can have different levels of redundancy in sensors, controllers, and actuators, and none of that relates to the "generation" of the aircraft.

The authors of the article: Adam Mathews, Anil B Lulla and Ninad D Sheth, and Open The Whatever belong on BR's ban list.

shiv · Post by **shiv** » 16 Jan 2011 16:28

kit wrote: A fly-by-wire aircraft normally has four circuits for each connection, meaning even if one circuit to the landing gear fails, three others will still operate.

Hmm interesting.. "Fly By Wire" means "has four circuits for landing gear". Very nice. These guys should write a textbook on aircraft. Anyone and everyone is allowed to crap on the internet, and there will always be someone to lick it off and swallow it.

Lalmohan · Post by **Lalmohan** » 16 Jan 2011 16:31

quad redundant, triple redundant, dual redundant, single FBW channel (s)
FMC = 1
FMS/AP = 1
actuators = '1' per control

the number of redundancies is a function of probability of failure of any 1 control loop
over the years, engineering reliability has been improving somewhat, so that quad may now be overkill

kit · Post by **kit** » 16 Jan 2011 16:44

PratikDas wrote:Kit, firstly, the claim that there are only two circuits is false:
Tarmak007: Surviving Sanctions only to become World-Beaters: Tracking the fly-by-wire FCS story from ADE (Part-III-A), 9 January 2011
Some of the highlights of the Onboard Software are Kernel working in real time, synchronization of the 4 identical computers, managing the redundancy to ensure accurate inputs for the Control Laws and the right drive to the actuators, software-controlled Built-In-Test for ensuring the health of the system before each flight.
Secondly, it seems like the authors of the Open The Orifice sorry, Magazine, article don't know what a fly-by-wire system is. Even if there is one and only one circuit handling all flight operations electronically, the system is still fly-by-wire.

Finally, you can have different levels of redundancy in sensors, controllers, and actuators, and none of that relates to the "generation" of the aircraft.

The authors of the article: Adam Mathews, Anil B Lulla and Ninad D Sheth, and Open The Whatever belong on BR's ban list.

Thanks for the info !

Lalmohan · Post by **Lalmohan** » 16 Jan 2011 16:46

out of interest, space shuttle FMS works on 3 parallel systems computing flight path using 3 different algorithms and a 'majority vote' between them to chose the optimum control movements

shiv · Post by **shiv** » 16 Jan 2011 16:47

NRao wrote: However, in any of them the red pod is a camera pod. In all cases they are skewed to face what they are photographing (at real high speeds).

And here are some of the videos those cameras have captured - at 59 seconds
http://www.youtube.com/watch?v=KrTj4ywIjnw

Kartik · Post by **Kartik** » 16 Jan 2011 23:23

kit wrote:The Tejas is touted as a fly-by-wire system; that is, one that uses sophisticated computer electronics to make it as foolproof as possible. A fly-by-wire aircraft normally has four circuits for each connection, meaning even if one circuit to the landing gear fails, three others will still operate. But in reality, the Indian Tejas has only two such circuits, not four. Technically it does not qualify as a fly-by-wire aircraft. And guess what India is handling in the fifth-generation fighter project it is planning with Russia—the fly-by-wire system.

http://www.openthemagazine.com/article/ ... sible-bird

??!

if ever there was a bogus article, this is one. The Numbskulls who wrote it apparently cannot fathom what Quadruplex FBW means. That pretty much means that all their conclusions are rubbish.

Surya · Post by **Surya** » 16 Jan 2011 23:28

Adam Mathews, Anil B Lulla and Ninad D Sheth

The three Einsteins who contributed to that article

Sriman · Post by **Sriman** » 16 Jan 2011 23:45

Kartik · Post by **Kartik** » 17 Jan 2011 00:04

Surya wrote:Adam Mathews, Anil B Lulla and Ninad D Sheth

The three Einsteins who contributed to that article

it took 3 of them to come up with THAT ?!

Imagine what 1 of them on his own would've written ?!

They'd be laughed off BRF itself !!

ramana · Post by **ramana** » 17 Jan 2011 00:32

They are the Three Idiots of Aviation reporting!