LCA News and Discussions

Gurneesh · Post by **Gurneesh** » 14 Jun 2013 20:57

merlin wrote:
Kartik wrote:
It flew at +6Gs at AeroIndia itself and the 22 deg alpha has also been achieved. Both confirmations from Cmde Maolankar at AI-'13.
At this AI it must have flown at +6G but at the one prior to this one it did hit +8G (not authorized, so must have been done accidently).

If 22 alpha has been reached then the only one blocking IOC-2 must be wake penetration and lightning protection.

Doing it accidentally might have been possible with legacy non-FBW systems. But in LCA, shouldn't the FBW should keep the aircraft within the required (<+6 G) limits at all times. Either the +8 G did not happen, or it was intended by HAL (which begs the question as to why they did not pursue it further?) or there was a failure in FBW which allowed the aircraft to depart from the certified safe limits.

suryag · Post by **suryag** » 14 Jun 2013 21:16

Gurneesh ji you probably missed Dr.Shyam Chetty's talk this AI where he mentioned how difficult it is to avoid intentional/unintentional deviation(from the perspective of an algorithm) from the specified capability. So the FCS might not be entirely bullet proof in restricting capabilities.

nachiket · Post by **nachiket** » 14 Jun 2013 22:17

Ekalavya and co., can you please take the MKI vs Rafale discussion to the Mil Aviation or Su-30 threads?

Indranil · Post by **Indranil** » 14 Jun 2013 23:30

Gurneesh wrote:
merlin wrote:
At this AI it must have flown at +6G but at the one prior to this one it did hit +8G (not authorized, so must have been done accidently).
Doing it accidentally might have been possible with legacy non-FBW systems. But in LCA, shouldn't the FBW should keep the aircraft within the required (<+6 G) limits at all times. Either the +8 G did not happen, or it was intended by HAL (which begs the question as to why they did not pursue it further?) or there was a failure in FBW which allowed the aircraft to depart from the certified safe limits.

I actually agree with you (except that I think you meant ADA in stead of HAL). But there might be a third possibility. That the FBW is limiting the plane to 8G. The test pilots take it through the paces. This is common practice for aircraft testing. For example the top speed of the aircraft is not limited by FBW. But the pilots take time to get it there.

On a demo, they took it further as they had sufficient faith in the machine. Probably, they should not have. But that is just one maneuver with only wing tip pylons. Surely this does not cover all test conditions.

SaiK · Post by **SaiK** » 15 Jun 2013 05:29

^are you saying test pilots were not restricted on their mission profile, and flying under certain g-limits should be under those restrictions right?

Indranil · Post by **Indranil** » 15 Jun 2013 08:14

Of course they are restricted. And they follow them very strictly. Even in AI, All the maneuvers displayed are decided before hand. The designers and the pilots may be confident enough about certain regimes of the flight. But for operational clearance, they have to go through all the tests.

Kartik · Post by **Kartik** » 15 Jun 2013 08:26

merlin wrote:
At this AI it must have flown at +6G but at the one prior to this one it did hit +8G (not authorized, so must have been done accidently)

Source?

merlin · Post by **merlin** » 15 Jun 2013 22:12

Kartik wrote:
merlin wrote:
At this AI it must have flown at +6G but at the one prior to this one it did hit +8G (not authorized, so must have been done accidently)
Source?

An ADA employee told me that during AI 2011. He also said that to go +8G again, the structural guys will have to formally clear it.

SaiK · Post by **SaiK** » 16 Jun 2013 20:51

well, the structural guys should have designed it for +8 to -3.5, that is per ADA.gov site.

Austin · Post by **Austin** » 16 Jun 2013 21:20

I hope when Tejas achieves IOC they start sending it to Airshows specially the big international ones and our own AI , Hopefully atleast two so that we can see some good aerobatics from it and also a good opportunity for business

Indranil · Post by **Indranil** » 16 Jun 2013 22:07

SaiK wrote:well, the structural guys should have designed it for +8 to -3.5, that is per ADA.gov site.

No. For stress related tests. They would fly the plane and monitor stresses at critical parts of the plane. Then structural guys will test the structure for any untoward bending or cracks. Then the plane will be cleared for the next tests and so on.

Kartik · Post by **Kartik** » 17 Jun 2013 11:43

indranilroy wrote:
SaiK wrote:well, the structural guys should have designed it for +8 to -3.5, that is per ADA.gov site.
No. For stress related tests. They would fly the plane and monitor stresses at critical parts of the plane. Then structural guys will test the structure for any untoward bending or cracks. Then the plane will be cleared for the next tests and so on.

I think what SaiK meant is that the airframe itself would be able to fly to +8G without any issues. the Tejas having been designed to +9G originally (the +8G restriction was imposed later, probably due to weight), would be structurally able to withstand close to 13Gs without suffering a critical failure. +8G would not require any inspection.

Indranil · Post by **Indranil** » 17 Jun 2013 12:45

Kartik,

I understand what you are saying. But during testing, they would check after every few tests. After IOC, they would definitely not check till they come to the point of ascertaining how much life is left in the airframe.

SaiK · Post by **SaiK** » 17 Jun 2013 17:20

Another thing to know is the product life cycle, and methods of engineering. I can V&V all these structural aspects on the ground if we have that setup. So, the only thing must be testing all integrated, and this should not be that difficult having structurally proven on the ground., like claws software config, changes, calibrations, measurements or other feedback corrections into algo etc.

Lalmohan · Post by **Lalmohan** » 17 Jun 2013 19:12

there is an airframe that is set up on a special rig and then vibrated for years until it starts to crack - simulates flight cycle loading through lifetime - to do fatigue testing

SaiK · Post by **SaiK** » 18 Jun 2013 02:24

they can also subject the air-frame to both super and hyper-sonic wind tunnel to study under high temp and pressure treatment depending on the design of the structure.

suryag · Post by **suryag** » 18 Jun 2013 11:14

Flight test update

From

LCA-Tejas has completed 2199 Test Flights Successfully. (13-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-136,LSP4-82,LSP5-178,LSP7-43,NP1-4,LSP8-6)

to

LCA-Tejas has completed 2206 Test Flights Successfully. (15-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-138,LSP4-82,LSP5-180,LSP7-44,NP1-4,LSP8-8)

Kartik · Post by **Kartik** » 18 Jun 2013 11:44

the momentum of flight tests appears to be picking up. 7 flights in 2 days and finally LSP-8 seems to be put through its paces.

Lalmohan · Post by **Lalmohan** » 18 Jun 2013 12:16

SaiK wrote:they can also subject the air-frame to both super and hyper-sonic wind tunnel to study under high temp and pressure treatment depending on the design of the structure.

not on a full scale aircraft they can't

NRao · Post by **NRao** » 18 Jun 2013 12:31

Kartik wrote:the momentum of flight tests appears to be picking up. 7 flights in 2 days and finally LSP-8 seems to be put through its paces.

That was the first idea of the new head.

Lalmohan wrote:
SaiK wrote:they can also subject the air-frame to both super and hyper-sonic wind tunnel to study under high temp and pressure treatment depending on the design of the structure.
not on a full scale aircraft they can't

Does India have any sized wind tunnel for "super and hyper-sonic" speeds? Just curious.

rajanb · Post by **rajanb** » 18 Jun 2013 12:34

suryag wrote:Flight test update

From

LCA-Tejas has completed 2199 Test Flights Successfully. (13-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-136,LSP4-82,LSP5-178,LSP7-43,NP1-4,LSP8-6)

to

LCA-Tejas has completed 2206 Test Flights Successfully. (15-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-138,LSP4-82,LSP5-180,LSP7-44,NP1-4,LSP8-8)

There was a post earlier saying that the LCA still had to go Lightning Certification Tests.

If I remember correctly, there was a monsoon season where Suryag and I had lamented that there had been no flights because we suspected that the LCA was not certified for all weather operation.

With the weather the way it is all over the country, I am fairly certain, that this milestone had been passed and that leaves three major milestones (I suspect the AoA has been achieved): the wake penetration, the spin chute test and the BVR missile testing.

Please correct if I am wrong.

The LSP-8's increase in flights points to pushing closer to IOC-2?

Nikhil T · Post by **Nikhil T** » 18 Jun 2013 12:51

==self deleted ==

Singha · Post by **Singha** » 18 Jun 2013 15:30

VSSC trivandrum as well iirc. one will come up in new defence labs campus chitradurga too.

merlin · Post by **merlin** » 18 Jun 2013 17:13

rajanb wrote:
suryag wrote:Flight test update

From

LCA-Tejas has completed 2199 Test Flights Successfully. (13-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-136,LSP4-82,LSP5-178,LSP7-43,NP1-4,LSP8-6)

to

LCA-Tejas has completed 2206 Test Flights Successfully. (15-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-138,LSP4-82,LSP5-180,LSP7-44,NP1-4,LSP8-8)
There was a post earlier saying that the LCA still had to go Lightning Certification Tests.

If I remember correctly, there was a monsoon season where Suryag and I had lamented that there had been no flights because we suspected that the LCA was not certified for all weather operation.

With the weather the way it is all over the country, I am fairly certain, that this milestone had been passed and that leaves three major milestones (I suspect the AoA has been achieved): the wake penetration, the spin chute test and the BVR missile testing.

Please correct if I am wrong.

The LSP-8's increase in flights points to pushing closer to IOC-2?

Well, the LCA is flying in Bangalore and its not raining heavily in Bangalore. In fact, in the monsoon, unlike pre-monsoon there is usually no thunder and lightning. So might not be lightning tested - no way of telling after the HAL/ADA news blackout.

SaiK · Post by **SaiK** » 18 Jun 2013 17:35

NRao wrote: Does India have any sized wind tunnel for "super and hyper-sonic" speeds? Just curious.

If we want a product to work on those lines, we better have it. We can't keep sending things to Russia and Amrikka for ever.

Lalmohan · Post by **Lalmohan** » 18 Jun 2013 18:15

saik - to the best of my meagre knowledge - no one has supersonic and hypersonic tunnels for full scale tests; it is not practical

rajanb · Post by **rajanb** » 18 Jun 2013 18:54

merlin wrote:
rajanb wrote: There was a post earlier saying that the LCA still had to go Lightning Certification Tests.

If I remember correctly, there was a monsoon season where Suryag and I had lamented that there had been no flights because we suspected that the LCA was not certified for all weather operation.

With the weather the way it is all over the country, I am fairly certain, that this milestone had been passed and that leaves three major milestones (I suspect the AoA has been achieved): the wake penetration, the spin chute test and the BVR missile testing.

Please correct if I am wrong.

The LSP-8's increase in flights points to pushing closer to IOC-2?
Well, the LCA is flying in Bangalore and its not raining heavily in Bangalore. In fact, in the monsoon, unlike pre-monsoon there is usually no thunder and lightning. So might not be lightning tested - no way of telling after the HAL/ADA news blackout.

@Merlin. I can see the LCA at times from my place. I also, in the last 6 weeks have seen fabulous streaks of lightning. Mostly between clouds, rather than clouds to ground which is rarer. Technically when you have the sort of breeze that BLR is witnessing; of moisture laden skies scudding across the sky at fairly low levels, the amount of ionisation is quite high. Introduce an object flying at high speeds into that atmosphere is most likely to disturb the differing electric charge levels leading to lightning which equalises the potential difference between objects in the sky. Lightning's relative unpredictability limits a complete explanation of how or why it occurs, even after hundreds of years of scientific investigation.

Because of this "relative unpredictability" and the extreme care that has been taken in the (touch wood) testing record of the LCA, I am fairly certain that they have now taken care of the possibility of any discharge between the a/c and its environment. I had read a while back that the composite structure had electrically conducting elements one layer below the composites, in the LCA, to ensure an unbroken path for the a/c to disperse its electric charge. And yet, as per the FAA, a/c do get struck by lightning. So the protection is to ensure that such strikes quickly flow off the a/c and ensure it does not explode vapourised fuel, weld joints together, etc.

Here is a nice article on lightning protection for composite structures, particularly in a/c. http://www.compositesworld.com/articles ... structures

Cheers,

SaiK · Post by **SaiK** » 19 Jun 2013 07:55

Lalmohan wrote:saik - to the best of my meagre knowledge - no one has supersonic and hypersonic tunnels for full scale tests; it is not practical

nasa, langley, va

NRao · Post by **NRao** » 19 Jun 2013 10:46

SaiK wrote:
Lalmohan wrote:saik - to the best of my meagre knowledge - no one has supersonic and hypersonic tunnels for full scale tests; it is not practical
nasa, langley, va

True. There are others too (2-3 more). However, the largest one I think is 10'x10'x40'. And is used to test full scale engines/rockets and not the entire craft. ?????

I doubt India has any.

SaiK · Post by **SaiK** » 19 Jun 2013 18:15

almost there.. but here you go:
http://www.nasa.gov/centers/langley/new ... 30X60.html

India: IIT, kanpur : limited scope

DRDO to invest 1k crore on windtunnel.. dunno state?

of course there are other dedicated facilities:
http://atfi.dlis.du.ac.in/WT.html

jamwal · Post by **jamwal** » 19 Jun 2013 21:54

suryag wrote:Flight test update

From

LCA-Tejas has completed 2199 Test Flights Successfully. (13-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-136,LSP4-82,LSP5-178,LSP7-43,NP1-4,LSP8-6)

to

LCA-Tejas has completed 2206 Test Flights Successfully. (15-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-138,LSP4-82,LSP5-180,LSP7-44,NP1-4,LSP8-8)

Apologies if this post is a result of sleep deprivation, but counting 2 flights each from 3 planes, it should be 6 flights in 3 days. What am I missing here ?

member_22906 · Post by **member_22906** » 19 Jun 2013 22:14

^^ u missed 1 flight of LSP 7

jamwal · Post by **jamwal** » 19 Jun 2013 22:31

suryag ki galti hai

karan_mc · Post by **karan_mc** » 19 Jun 2013 23:38

New DRDO chief was talking about 40 flights a month for FOC to be achieved in time am i right .

putnanja · Post by **putnanja** » 19 Jun 2013 23:51

Flight test update

From

LCA-Tejas has completed 2206 Test Flights Successfully. (15-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-138,LSP4-82,LSP5-180,LSP7-44,NP1-4,LSP8-8)

To
LCA-Tejas has completed 2208 Test Flights Successfully. (18-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-273,PV5-36,LSP3-138,LSP4-82,LSP5-180,LSP7-45,NP1-4,LSP8-9)

NRao · Post by **NRao** » 20 Jun 2013 00:07

SaiK wrote:almost there.. but here you go:
http://www.nasa.gov/centers/langley/new ... 30X60.html

May be it was replaced? But .....................

.......................was NASA's oldest operating wind tunnel until its closing in October of 1995.

SaiK · Post by **SaiK** » 20 Jun 2013 01:12

yes, they moved to nasa, ames. 80x120 ' wala.
http://rotorcraft.arc.nasa.gov/Research ... nnels.html

subsonic though

Karan M · Post by **Karan M** » 20 Jun 2013 02:21

Sagar G wrote:
Austin wrote:With a Mig-21 Bison crashing this time, resentment building in IAF against DRDO, HAL for delay in induction of LCA Tejas
LCA is already successful for me given the sheer amount of Khujli it generates among different organizations and individuals. Arunachalam was right on the dot about this being a season for DRDO bashing.

Karan M wrote:The missile status isnt that bad. The r77 with its issues worked out is a decent ARH. Similarly R73E with Sura and TVC is deadly. Astra feature set now extends from quasi CCM to BVR and includes 3rd party desig and some nifty features. True the meteor if it isnt jammed is a game changer but once LRSAM is done expect its tech to find its way to Astra or similar programs- the dual thrust motor in specific.
3rd party is indigenous or foreign ???

3rd party designation means that one LCA paints, the other fires. This is a pretty significant capability.

This is what DRDL noted in Aero India, earlier in the year.

All Aspect
All Weather
BVR & CCM
Active Radar Terminal Guidance
Excellent ECCM Features
Smokeless Propulsion
Improved Effectiveness in Multi-Target Scenario

Launch Modes
Dual Mode Guidance
Autonomous Mode Guidance
Buddy Mode
Slaving of Seeker with IRST / HMS
Seeker Autonomous Search Mode before Launch
Lock-on Before Launch (LOBL)
Lock on After Launch (LOAL)
Off-Bore_Sight Launch up to 45 deg either side

The parts in bold are the one that are impressive, as they indicate the Astra can bridge the gap between a CCM and a BVR missile and can also be guided by another aircraft. This permits sneaky tactics. The Sea Harrier LUSH upgrade also conferred this capability on the platform per IN reports. In Russian tests, Su-30s guided missiles fired by MiG-31s, but the IAF has been justifiably quite if they have implemented something similar.

SaiK · Post by **SaiK** » 20 Jun 2013 08:08

If LCAs can reach higher stealth content, then essentially it can form a buddy squad around about 1 mki + 8 LCAs to take the cue from MKI. A fuel probe and refueler support from the rear is all that takes for even deeper strikes.. 4-8 such squad, pretty much to anywhere from karachi to peshawar, back to base. i did not consider of course, weapons config and reload.

Sagar G · Post by **Sagar G** » 21 Jun 2013 17:54

Karan M wrote:3rd party designation means that one LCA paints, the other fires. This is a pretty significant capability.

Ohh you meant "designation" I thought you were saying "design", thanks for clarifying.