LCA News and Discussions

SaiK · Post by **SaiK** » 05 Mar 2013 23:00

immovable louvers means fixed intake right? I guess the question would be if these louvers are spring loaded to close and open like in ghar ka blinds? so, you can get to choose the second class RAC effect and can sneak into first class a/c when the TT dozes off?

Indranil · Post by **Indranil** » 06 Mar 2013 01:02

SaiK wrote:immovable louvers means fixed intake right?

No. They are physically "fixed", but the air intake through them is not fixed.

Instead, it will be dependent on the pressure difference just like the auxiliary door. At low speed and high thrust (for example at take off or landing speeds), the engine requires more air than what the intakes can provide. So there is a lower pressure inside the intake. This makes the auxiliary doors open to let in more air. At higher speeds, when the inlets can provide the engines with sufficient quantities of air, the pressure difference drops and the door is shut. In a louver, no air is sucked it.

The problem with spring loading is that the stiffness of the spring. It is difficult to choose it correctly such that the door opens adequately when required, while at the same time does not react to turbulence. Also, bear in mind that the stiffness of the spring changes as it ages.

suryag · Post by **suryag** » 06 Mar 2013 01:24

IR ji what happens in case of Leh kind of env when the engine is starving? Would there be different kind of setting, i am not sure if there is a mass flow sensor in that air intake to decide if the auxillary door needs to be opened

pentaiah · Post by **pentaiah** » 06 Mar 2013 01:26

Think of the design to peg the springs the perforations and or notches (like on spring cots in the soldiers barracks) will weaken the member( pun ya fun kuch be so cho Zara)
The lovers can be riveted wit play if you want a small angular displacement
Remember in blinds ( at home Saik ji refers to) the blinds pivot by shortening and increasing the length of the strings and pivot a real Louvere is just a notch at an angle.

pentaiah · Post by **pentaiah** » 06 Mar 2013 01:29

suryag wrote:IR ji what happens in case of Leh kind of env when the engine is starving? Would there be different kind of setting, i am not sure if there is a mass flow sensor in that air intake to decide if the auxillary door needs to be opened

Have you driven a car to Denver or driven a vehicle to Badarinath kedarnath
The engine auto magically derates because of air density changes
The mass will be reduced no question but the sensor will be calibrated and performance derated
( switch the a/c in the car you will notice engine straining)

SaiK · Post by **SaiK** » 06 Mar 2013 02:06

Thanks for the explanations IR.. and pentaiah ji, that would explain clear for Nick s question, and answers the drag as well. basically, there is no question of drag if the mechanism pushes the louvers to inlet surface level, and there is no separate door which I earlier thought was wrong.. in that wrong thought case, I was wondering how they would bleed off unwanted air at true air flow needs for sustained cruise or reduced intake flow. more clarity now! pentaiah ji jai ho!

Nick_S · Post by **Nick_S** » 06 Mar 2013 05:17

Thank you indranilroy and pentaiah ji.

ramana · Post by **ramana** » 08 Mar 2013 06:36

Aeromag Issue on LCA
http://www.aeromag.in/sites/default/fil ... 202013.pdf

suryag · Post by **suryag** » 08 Mar 2013 13:19

Flight test update

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)

to

LCA-Tejas has completed 2074 Test Flights Successfully. (06-Mar-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-353,LSP1-74,LSP2-257,PV5-36,LSP3-108,LSP4-68,LSP5-145,LSP7-27,NP1-4)

Austin · Post by **Austin** » 08 Mar 2013 14:01

ramana wrote:Aeromag Issue on LCA
http://www.aeromag.in/sites/default/fil ... 202013.pdf

Nice find ramana , Thanks for posting.

Singha · Post by **Singha** » 08 Mar 2013 14:13

a comment seen on livefist. is that the case?

When we design the intakes it needs to take 60 % more air than the required air volume so that it can generate full thrust at high altitudes.

shiv · Post by **shiv** » 08 Mar 2013 15:49

Singha wrote:a comment seen on livefist. is that the case?

When we design the intakes it needs to take 60 % more air than the required air volume so that it can generate full thrust at high altitudes.

Sounds like someone with the same qualifications as me in designing aircraft and engines. My birather.

Kartik · Post by **Kartik** » 08 Mar 2013 15:58

ramana wrote:Aeromag Issue on LCA
http://www.aeromag.in/sites/default/fil ... 202013.pdf

PS Subramanyam's interview confirms exactly what Cmde Maolankar had said to me during AI-13 regarding the alpha that the Tejas Mk1 has attained so far and what it will attain by FOC..although I was told by Cmde Sukesht that the Mk2 will be full 9G capable, the Mk1 will be 8G capable.

After the IOC clearance, we are going to work towards FOC in which we will envisage the flight envelope of the aircraft from the 22 degree of angular attack to 24 degree of attack and the maneuvering of the aircraft from 6 g to 8 g

what I'd written

Tejas Mk1 has achieved the IOC AoA limit of 22 deg and they will go a couple of degrees further in tests, when the spin chutes are integrated on LSP6. This is to ensure that they know that the airplane is safe even at higher alpha although the FBW will restrict it to the AoA limit for FOC for service pilots (which is higher than 22 deg, but he didn’t say how much)

so it now appears that when he said that they will go even a couple more degrees over the final alpha limit set by the FBW, he meant around 26 degrees alpha.

Another point he made which I'd noted is now also proven by seeing the Mk2's intake auxiliary louvers in place of the spring actuated auxiliary air intakes.

I'd written

They have already tried various intakes on the LCA, with/without spring mounted doors on the intakes.

and livefist got the image from NAL of the Tejas Mk2's air-intake model that showed the louvers.

Also note that PS Subramanyam didn't mention anything about AESA radar for the Tejas Mk2- and neither did Cmde Sukesh. So it may well be that we'll get a provisional Elta 2032/MMR radar on the Mk2 initially and then later batches may get an AESA.

I'd written.

When quizzed about AESA for the N-LCA Mk2, he said that for now it’s the same Elta 2032 and Cmde Mao had recently even gone to Israel to test the radar that will be used on the N-LCA Mk2.

NRao · Post by **NRao** » 08 Mar 2013 19:33

Feb 2011 :: LCA Technologies

Two years old, but a good ref and perhaps provides what progress has been made.

SaiK · Post by **SaiK** » 08 Mar 2013 20:06

nice corroborations there kartik.

read about low observability in the above article.

putnanja · Post by **putnanja** » 08 Mar 2013 22:02

Why was the max G limit reduced to 8G for Mk-I? What changes will increase it to 9G in Mk-II?

Indranil · Post by **Indranil** » 09 Mar 2013 00:55

Kartik wrote: so it now appears that when he said that they will go even a couple more degrees over the final alpha limit set by the FBW, he meant around 26 degrees alpha.

This has been known for some time now. Mk-1 will probably be limited to the 24 degrees. Mk-2 with taller v. stab will probably be taken to 26 degrees. You would remember our discussion on this
AN APPROACH TO HIGH AoA TESTING OF THE TEJAS LCA

CL max And Usable AoA Considerations
Wind tunnel experiments have indicated that CL max continues to improve till approx 35 degrees AoA. However, directional characteristics indicated the proverbial ‘cliff’ with a sudden drop in CnB, CRM (Coefficient of Rolling Moment) and CYM (Coefficient of Yawing Moment) at approx 25 degrees AoA. These phenomena require the High AoA trials to be limited to 24 degrees until directional stability is bolstered and augmented by rudder control up to an expected 26.
....
Fortunately, the LCA has significant rudder authority (CYM-Del R) even up to 30 degrees AoA and that will allow artificial stabilization in yaw at high AoA

SaiK · Post by **SaiK** » 09 Mar 2013 01:16

Is the 9g human/pilot tolerance or airframe?

Indranil · Post by **Indranil** » 09 Mar 2013 02:42

~~SaiK wrote:Is the 9g human/pilot tolerance or airframe?~~

putnanja wrote:Why was the max G limit reduced to 8G for Mk-I? What changes will increase it to 9G in Mk-II?

Definitely airframe. The degradation is because the structures were designed for lower clean take off weight. They will address this in Mk2.

P.S. corrected the quotes.

member_22872 · Post by **member_22872** » 09 Mar 2013 03:22

From Feb 2011 :: LCA Technologies:

Structured multi-block grid-based NS solver CNS3D was used for studying aircraft flow fields, especially those related to high AoA.

Indranil Roy ji,
why is that they used structured mesh for this? is it because of BL separation at high AoA?

Indranil · Post by **Indranil** » 09 Mar 2013 03:41

venug wrote:From Feb 2011 :: LCA Technologies:
Structured multi-block grid-based NS solver CNS3D was used for studying aircraft flow fields, especially those related to high AoA.
Indranil Roy ji,
why is that they used structured mesh for this? is it because of BL separation at high AoA?

Please no "ji'.

I don't know why they used a structured mesh. But from my knowledge of high performance computing, a structured multiblock grid-based system can be easily parallelized.

There are many aspects to high AoA testing besides boundary layer separation.

member_22872 · Post by **member_22872** » 09 Mar 2013 03:59

Indranil Saar, It appears so. For a configuration of the size of airplane, it might not be practical without parallelism. But now parallel solvers with unstructured meshes too are available. But again as you said, it is easier with structured meshes and also looks like it is developed in-house. Nice.

SaiK · Post by **SaiK** » 09 Mar 2013 07:58

http://www.scribd.com/doc/122140248/CFD-in-india

srai · Post by **srai** » 09 Mar 2013 08:05

SaiK wrote:Is the 9g human/pilot tolerance or airframe?

AFAIK, yes on human/pilot tolerance. Only very few extraordinary individuals can handle more than 9G. Even 9G is rarely reached but only for the briefest of moments. Most would blackout under the G stress as a result of lack of oxygen to the brain. G-Suits help only so much.

pentaiah · Post by **pentaiah** » 09 Mar 2013 19:23

srai wrote:
SaiK wrote:Is the 9g human/pilot tolerance or airframe?
AFAIK, yes on human/pilot tolerance. Only very few extraordinary individuals can handle more than 9G. Even 9G is rarely reached but only for the briefest of moments. Most would blackout under the G stress as a result of lack of oxygen to the brain. G-Suits help only so much.

Except women

The reality is that women can counteract G-forces because their physiology makes them more tolerant of G-forces than men.
(G-forces push down on a body, they overcome the ability of the heart to pump oxygenated blood upward into the brain. Blood begins to pool in the lower extremities, while blood circulation to the head is reduced. When blood circulation to the head is sufficiently reduced, the oxygen supply to the brain becomes insufficient.)
Height, not strength or gender, is the most negative factor in a pilot's ability to tolerate G stress. Because women have a smaller body mass the shorter distance between their heart and brain makes it easier for them to counteract the G-forces. Advances in centrifuge technology and training , special exercises, and newer G-suits are making marked improvement in aircrew G-tolerance.

{Because women have a smaller body mass the shorter distance between their heart and brain }

That's the reason they say love is blind

SaiK · Post by **SaiK** » 09 Mar 2013 22:10

JC!! we need more wimmen afsars as IAF pilots!!!

srai · Post by **srai** » 10 Mar 2013 10:58

^^^

Doesn't say that women can tolerate more than 9G. It only says their physiology makes them likely to handle higher Gs but not an actual number. We are talking about 9G limit here.

JTull · Post by **JTull** » 10 Mar 2013 13:39

Why not shorter men?

Cybaru · Post by **Cybaru** » 10 Mar 2013 14:32

JTull wrote:Why not shorter men?

Then unfortunately it will become politically incorrectly known as Lilliput Combat Aircraft...

ArmenT · Post by **ArmenT** » 10 Mar 2013 14:46

Cockpit layout also needs designed with g-forces in mind. The most critical controls need to be reachable by the pilot even in high-G situations. The fun thing about modern fighter cockpits is that they are normally designed for use by a large percentile of the male population of the country of origin of the fighter. So they decide the height of the pedals, controls etc. based on the average body measurements of X percentile of the male population. The problem is that many of the female population's physical dimensions fall outside this X percentile. Not only that, when a country imports fighters from another country with a very genetically different population, (e.g. SDRE countries or tall African countries importing fighters designed by Sweden) also have a smaller pool of potential pilots to choose from.

With LCA, the cockpit is designed to fit average Indian males, so it may actually have an export edge to other countries with citizens of similar dimensions (e.g.) some central american/south american, SE Asian, Carribbean countries, some parts of Africa etc.

Philip · Post by **Philip** » 10 Mar 2013 16:30

Anyone know what the approx AOA of the LCA is meant to be?

shiv · Post by **shiv** » 10 Mar 2013 19:48

Philip wrote:Anyone know what the approx AOA of the LCA is meant to be?

Philip I vaguely recall that the figure demanded was 24 deg.

SaiK · Post by **SaiK** » 10 Mar 2013 20:56

ArmenT, agree, but we could definitely have export versions for other countries if reach-ability is all the game there... If we think a little bit more ..then all can be done in configurable and adjustable systems [simple mechanics].

Any other G-specific genetic configuration needed?

manum · Post by **manum** » 10 Mar 2013 22:22

I just dont think Indian armed forces use different dimensions than europian, American or Russian...
so there is nothing like made for short men...but ya dimensions are not fit for 6.5-7 fit men....

As much as Female pilot is concerned...they can have requirement of ramp model height...that would help a lot of G's...

SaiK · Post by **SaiK** » 11 Mar 2013 01:54

hey! not suitable to discuss that here.

Raja Bose · Post by **Raja Bose** » 11 Mar 2013 02:42

Actually ramp models will have more problems countering higher Gs due to their taller height. What is wanted is Rani Mukherjee types rather than Pooja Batra types.

NRao · Post by **NRao** » 11 Mar 2013 06:09

The lca was designed with Indian pilots in mind. More: http://livefist.blogspot.com/2010/11/ex ... s.html?m=1

We had a big discussion in the very early days on this matter.

SaiK · Post by **SaiK** » 11 Mar 2013 06:19

why can't a car type 8 way seat adjuster work?.. except for the ejection system?

suryag · Post by **suryag** » 12 Mar 2013 12:59

Flight test update

LCA-Tejas has completed 2074 Test Flights Successfully. (06-Mar-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-353,LSP1-74,LSP2-257,PV5-36,LSP3-108,LSP4-68,LSP5-145,LSP7-27,NP1-4)

to

LCA-Tejas has completed 2084 Test Flights Successfully. (11-Mar-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-353,LSP1-74,LSP2-258,PV5-36,LSP3-113,LSP4-68,LSP5-147,LSP7-29,NP1-4)

Austin · Post by **Austin** » 12 Mar 2013 22:42

AW&ST:Indian Officials: Tejas On Its Way Up

In a clear confidence-building measure amidst chronic delays, India's homegrown Tejas Light Combat Aircraft (LCA) will be deployed for the first time in an air force exercise, code-named Iron Fist, over the Thar Desert in western India. Essentially a demonstration of air-delivered firepower, Iron Fist will see the Tejas for the first time fire air-to-air and strike weapons while flying in battlefield conditions with other Indian air force (IAF) aircraft, including the Su-30 MKI, Mirage 2000H, Jaguar, MiG-21, MiG-27 and MiG-29. Saddled with delays in a critical envelope expansion effort, the Tejas is looking to achieve the second phase of initial operational clearance by June, with a final operational capability and squadron service in 2015.

During Iron Fist, a limited series Tejas—one of eight such aircraft, with the eighth to fly next month—will deploy the R-73 close combat air-to-air missile and a series of laser-guided bombs. A day/night exercise, it will be the first time the IAF gets to fly the Tejas in a fully operational environment, including its surveillance and space assets. The IAF is also eager to test the aircraft's EL/M-2052 radar in an environment with other aircraft and targets. Series production of the Tejas is set to begin next year.

“There is confidence in the Tejas now. Scheduled to be inducted into a newly raised squadron in the Sulur air base [in southern India] in 2015, the IAF was keen to field the Tejas in this year's firepower demonstration to get a feel of how it operates in real conditions. Accordingly, it was decided to invite the program to participate,” said an IAF officer on detachment to fly at the Iron Fist exercise.

In its final configuration, which needs to be proven before 2014, the Tejas will deploy the R-77 and Derby Beyond Visual Range Air-to-Air Missiles (BVRAAMs) and the Python-5 close combat missile. Once ready, India's Astra BVRAAM will also be part of the Tejas weapons package. The missile is scheduled for a first firing from the air this year.

“The LCA is ready for operational conditions. We've waited for an opportunity like this to demonstrate how easily it will fit in with the IAF's existing strength. We look forward to operating with other pilots and aircraft types for the first time. It will go a long way toward establishing confidence in the platform. There's no substitute for that ahead of squadron service,” says a senior test pilot with the National Flight Test Center, currently pushing the Tejas toward final operational clearance.

To achieve initial operational capability, the Tejas program will need to expand the platform's angle of attack, g-tolerance and weapons capability. Additionally, the Tejas needs to complete test points in all-weather operations, lightning clearance and wake-penetration. Though slowed by critical delays, the program marked 2,000 accident-free flights earlier this month.

“The delay in delivery is a problem. It needs to be speeded up to ensure that there are no further delays in delivery to the IAF,” India Defense Minister A.K. Antony said this month. In its latest round of trials, the Tejas completed a series of high-altitude tests at the Leh air base in northern India in January. IAF Air Chief Marshal Norman Browne indicated earlier this month that the trials had not been entirely successful, and that the platform's engine didn't perform as expected.

Modifications will be required. There is much work ahead. Development projects do indeed take time, but it is imperative that there are no further delays in the program. A lot of effort has been invested in it, including from the IAF. It needs to be ready for operations soon,” Browne said.

The IAF has ordered 48 Tejas fighters so far, and indicated a higher level of interest in the proposed Mk.2 version of the aircraft. It will be powered by an F414 turbofan and feature so-far unspecified aerodynamic improvements, an upgraded digital flight control computer, a unified electronic warfare suite, upgraded avionics, an onboard oxygen generation system, increased fuel capacity, a midair refueling probe and increased survivability. The Aeronautical Development Agency has begun building a wind-tunnel model and full-scale mock-up of the aircraft.

The naval variant of Tejas, which features a drooped nose, strengthened undercarriage and tailhook for arrested landings, remains on the ground after just four flights last year. Program sources indicate the platform's landing gear is undergoing a partial redesign through a consultancy with EADS, which is also helping execute the test program. Once ready to get back to flight test, the LCA-N, as it is designated, will resume testing at India's brand-new, shore-based test facility in Goa, where the navy has built a ski jump and arrester deck to practice carrier landings.