LCA News and Discussions

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Re: LCA News and Discussions

Postby SaiK » 30 Jun 2013 09:14

red flag mullah, i found some thing for you:
http://aerostudents.com/files/advancedA ... ummary.pdf

don't ask me questions from it though.

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Re: LCA News and Discussions

Postby member_26965 » 30 Jun 2013 09:30

You are right Victor. Nose droop and loads have led pressure on under carriage and it has made carriage heavy. The frontal portion has hardly any commonality in design, a lot less commonality in avionics, when compared to IAF version. ADA is struggling with the entire package, the LEVCON, the Undercarriage especially.

Misinformers like indranilroy use half baked truth to twist out of situation instead of taking the facts head on. The fact is that Quad digit FCS computer, LEVCON computer, auto throttle, nose droop, arrestor etc are a part of design which brings the aircraft to certain designed parameters helping it to land. Nothing is mutually exclusive. LEVCONS have not yet been tested.

LEVCON's have not just landing function, they have take off functions too, especially ramp take off.

ranji, kindly give it a break with the ref. to other members. put him on ignore if you need.

- Rahul

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Re: LCA News and Discussions

Postby Lalmohan » 30 Jun 2013 12:34

ranji - two things
dont understand your comment about fog - how does that create vortices?
and the two really big ones... on each wing... what about those?

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Re: LCA News and Discussions

Postby member_26965 » 30 Jun 2013 16:02

Fog: How it creates I don't Know. Plane landing into fog, does create vortex.

What about the vortex on wings? How different is from the vortex which is created in wings and how different is its control or regulation from normal methods like LERX, Chines etc? If it falls within the definition, you have been already replied in dummy's guide. If not, you can elaborate.

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Re: LCA News and Discussions

Postby Indranil » 30 Jun 2013 17:16

Victor wrote:
indranilroy wrote:The nose droop has nothing to with slower approach speed, better control at slow speed or greater lift. Is there any reason that it would?

No it doesn't and I didn't mean to imply that it did. The NLCA has better frontal view (because of droop nose), slower approach speed, better control at slow speed and greater lift (because of levcon) than the LCA and the latter should have these too if they are net-net positives in the interests of commonality.

Victor,
There are two things here.
1. The levcons add one more wing tip which will shed vortices. So, the combined lift to drag ratio is going to be lower than a clean wing.
2. At higher AoA, the levcons delay the flow separation over the wing thus allowing higher AoA (and lift) and lower stall speeds.

AF does not need lower landing speed, why should it pay the price? Nilesh's question was simple. Levcons allow higher AoA. So will it allow higher STR? He is not alone in asking this question. ADA is studying this. And Sukhoi definitely sees virtue in it.

Victor wrote:If there is in fact a meaningfully negative drag effect because of the droop, then it should either be redesigned to be more efficient or the LCA is a very bad candidate for a naval fighter and should be canned. It is already struggling with a weight issue and the NLCA is further burdened with the need for heavier landing gear and an arrestor hook. What little capacity it already has to carry armaments as a 'light' fighter will be further restricted by increased drag, making it practically useless. Better to use what we have learned and apply it to the NLCA2 with the GE414.

The droop adds drag by virtue of the higher frontal area. But it is a price that ADA is willing to pay. All naval fighters pay these kind of prices. It is their operational requirement. And all operational NLCAs will be powered by GE414s.

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Re: LCA News and Discussions

Postby JayS » 30 Jun 2013 21:35

indranilroy wrote:Just my thoughts as I am not sure of the nomenclature myself. There is a good chance that we both learn in the process.

I think the cranked delta wing would be the right description of LCA. And here are my reasons.

1. The anhedral at the wingroot is not maintained along the chord. They wanted to have the leading edge above and in front of the inlet for obvious advantages. But the trailing edge of this kind of a wing is the tailplane. So the twist allows that merge along the chord and the anhedral allows the merge along the span. So I would not call this wing a cranked wing.

2. The crank along the leading edge in the LCA is actually an interesting one. Similar to the Viggen, the sweep actually increases after the crank. In order to increase the air flow above the root, they have the boundary layer spill duct and also a turbulator strip running along the chord at the crank. But still the LCA wing is a delta wing and it is definitely cranked.

I understand why you want to call it a compound delta wing. But I don't understand why you want to call it a "compound double delta" wing.

Hi,
My bad, "compound double delta" was overkill. :mrgreen: My brain is rusted i guess, needs some polishing.

Agreed. Only thing from my side, it can't be called "Cranked arrow delta" (because it does not have that characteristic "kink" at TE, which gives the distictive arrow tip shape).

Well as long as we understand the wing completely, sementics doesn't matter much. :wink:

Some more doubts:
1. when we say "wing is twisted" (wash in/out), about which axis the wing sections are turned actually?? For ex: if i rotate inboard sections w.r.t. axis passing through TE, I will end up getting twist + anhedral both (like in LCA). This can't be pure twist. Then which axis should it be. I can think of two natural options: About mid points of those sections or the aerodynamics center of thoseperticular sections??

2. B Harry's article says (pg 85):
Two hollow spill ducts, next to leading edge, connect with the intake splitter and act as suction system for boundary layer/vortex control and reducing skin friction drag

I thought they act more like Blowing/Injection system and they blow air coming from intake splitters onto the root section of the wing to energige it and also enhancing LE vortex structure. How can it act as suction system? What am I missing here?
Last edited by JayS on 30 Jun 2013 22:21, edited 1 time in total.

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Re: LCA News and Discussions

Postby JayS » 30 Jun 2013 22:19

ranji wrote:nileshjr,

Can you point out a resource instead of giving your half gyan?

and if not here, where it had to be posted? Why is is irrelevant? You should be clear about it.


Lord, we come before Thee now,
At Thy feet we humbly bow;
Lord, we know not how to go
Till a blessing Thou bestow.
Grant that all may seek and find
Thee a gracious God and kind. :!:

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Re: LCA News and Discussions

Postby Gurneesh » 30 Jun 2013 22:34

ranji wrote:^^^^^ HAHAHAHAHAHA! This is a gem. On contrary, it helps reduction in AOA without letting the aircraft stall. ... and hence improving visibility.

Ignoring your arrogant taunt, your post does bring an interesting question in my mind.

Do the LEVCONS enable NLCA to achieve slower speeds at same AoA as compared to AF version or is it that LEVCONs simply allow the AoA to increase that much higher thereby enabling slower speed?

Flaps, slats, LERX and LEVCONs are all high lift devices used to enhance the performance over a standard aerofoil.

Now a couple of minutes on google tells me that while flaps will increase lift at all angles of attack, slats and lerx only extend the usable AoA range (thus increasing lift coefficient) as shown in the figure below.

source:http://adg.stanford.edu/aa241/highlift/highliftintro.html

Image

While this shows the use of slats over a DC-9 wing (as opposed to cranked delta of LCA), one main point to note from the article is:
Slats operate rather differently from flaps in that they have little effect on the lift at a given angle of attack. Rather, they extend the range of angles over which the flow remains attached.


Additionally, the paper below talks about the use of LERX on a delta wing MAV. On the second page they have a similar graph of lift coefficient vs AoA, wherein the use of LERX just extends the lift coefficient at higher AoA when the clean config starts to taper off without impacting the lift coefficient at lower AoAs.

http://icas.org/ICAS_ARCHIVE/ICAS2004/PAPERS/214.PDF

So, unfortunately your statement that I have quoted above is wrong and what I wrote in my original statement as well as what Indranil and others have been saying is correct!!

In a nutshell, LEVCONS will allow safe operation at higher AoA and decrease landing speeds. Meanwhile nose droop will aid in countering the required higher AoA and improve visibility.

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Re: LCA News and Discussions

Postby Lalmohan » 01 Jul 2013 01:54

ranji wrote:Fog: How it creates I don't Know. Plane landing into fog, does create vortex.

What about the vortex on wings? How different is from the vortex which is created in wings and how different is its control or regulation from normal methods like LERX, Chines etc? If it falls within the definition, you have been already replied in dummy's guide. If not, you can elaborate.


ah, are you referring to vortex shedding or boundary layer separation?

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Re: LCA News and Discussions

Postby SaiK » 01 Jul 2013 03:35

that would be the diverters right?

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Re: LCA News and Discussions

Postby member_26965 » 01 Jul 2013 06:39

nileshjr wrote:Lord, we come before Thee now,
At Thy feet we humbly bow;
Lord, we know not how to go
Till a blessing Thou bestow.
Grant that all may seek and find
Thee a gracious God and kind. :!:


What a looser. :rotfl: Can't even back up his less than quarter baked post resulting out of BENIS understanding.

lalmohan,

I have refereed to original assertion where LEVCON and LERX have been confused and some losers are refusing to acknowledge the difference because of their arrogance. I have not gone into details and the Vortex Control as a whole. My point being that LEVCON's in LCA Navy is for actively depressing AOA while landing.

A foot forward, LEVCON's can be used for assisting the NLCA when it takes off from carrier. It can be controlled for additional lift.

LEVCON has additional computer associated with it on the plane. It requires a additional processor because it needs to process data and achieve optimum angle of AOA.

The funny assertion by a funny expert that NLCA nose droop has nothing to do with drag etc is also wrong. Even in mutually exclusive roles, Nose droop or not, every component associated with aircraft is tailored to achieving optimum airflow results based on design.

Marten,

stop trolling :lol:

Gurneesh,

Regrets on I seemingly mocked impression.

Do the LEVCONS enable NLCA to achieve slower speeds at same AoA as compared to AF version or is it that LEVCONs simply allow the AoA to increase that much higher thereby enabling slower speed?


As mentioned above with reference to a funny expert, you too are not grasping the idea of LERX and LEVCON. Both are leading edge fitment and refers to placement of the said object. The question is why does ADA needs "Vortex Controllers?" A LERX assists in AoA to let it make efficient and not let plane stall. A controller can find an optimum angle for plane to land at depressed AOA with slow speeds. However, the controller can do many things and this being one and one of your descriptions that "enable NLCA to achieve slower speeds at same AoA." Since, ADA has given it a digital computer control, it is expected to work on same lines as its quad digital processor meant for overall FCS. It is a controller and the computer can be programmed for optimum take off and landing positions.

Google or Bing or Yahooo, all their searches for slats and LERX will bring you keyword specific results. Nowhere I have said that LEVCON cannot perform on traditional LERX domains.

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Re: LCA News and Discussions

Postby suryag » 01 Jul 2013 10:06

Flight test update

From

LCA-Tejas has completed 2242 Test Flights Successfully. (27-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-274,PV5-36,LSP3-147,LSP4-87,LSP5-190,LSP7-48,NP1-4,LSP8-15)

to

LCA-Tejas has completed 2247 Test Flights Successfully. (29-June-2013).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-365,LSP1-74,LSP2-274,PV5-36,LSP3-148,LSP4-90,LSP5-191,LSP7-48,NP1-4,LSP8-15)

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Re: LCA News and Discussions

Postby member_26965 » 01 Jul 2013 10:41

More proof of reduction of AOA with leading edges. This is ADA study. Some expert was claiming that I was not reading the ADA studies and he has read all to derive his conclusion.

http://arc.aiaa.org/doi/abs/10.2514/6.2008-336

Numerous attempts have been made to control vortex breakdown by suction and blowing and with various control surfaces:"‘. Leading edge devices have emerged as the most suitable devices for controlling the vortex and also for improving aerodynamic characteristics of delta wings. It has been observed that increases with leading edge flap deflection. It is believed that a component of lift in the direction of thrust is created. thereby reducing drag. Further enhancement in low speed characteristics is achieved by rounding the leading edge for better ratio". The deflected leading edge flap also improves the quality of flow at higher by reducing the effective angle of attack experienced by the wing. It has been observed that in a multi~slat configuration. slats can be scheduled to control the vortex dynamics at higher angles of attack.

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Re: LCA News and Discussions

Postby bmallick » 01 Jul 2013 11:22

Based on all the discussion going no with regards to Levcon's and whatever little I could read and understand on the internet and various papers, I have a few question for the guru's here.

a. Is it possible to deflect the Levcon's both upwards as well as downwards.

b. Let us say that the aircraft is at a AOA of 15 degree and the Levcon's are deflected downwards at an angle of 10 degree, in this the actual AOA of the levcon would be 5 degree. Does this lower the effective AOA of the wing, thus allowing the wing to operate to much higher actual AOA?How does this affect the flow over the wing?

c. Let us say that the aircraft is at a AOA of 5 degree and the Levcon's are deflected upwards at an angle of 10 degree, in this the actual AOA of the levcon would be 15 degree. Does this mean the levcon's which are at high AOA start generating vortex much earlier than in the case of a LERX? Does this allow the aircraft to go slower at the same AOA?

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Re: LCA News and Discussions

Postby member_26965 » 01 Jul 2013 11:39

I am not an expert but let me give you general over view. My last post quoting ADA states it is deflected to achieve results. It lowers AOA of wing. It clears your 1 & 2.

3) Yes, it can be one outcome of it.

LEVCONS don't perform alone. There are other control surfaces like elevon or elevon equivalents etc which act in tandem with the LEVCON to create an entire effect.

Specifically speaking about NLCA. It is an unstable design and Quad duplex fcs controls it from falling down. LEVCON's computer may be used for vortex correction and the main quad duplex fcs computer will stablise the entire aircraft with required play of other control surfaces. Since both aircraft is unstable and vortex control further de stablises the aircraft, has pros of achieving some rare AOA and cons of need for higher processor power, higher impact on landing gear etc.

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Re: LCA News and Discussions

Postby Lalmohan » 01 Jul 2013 12:10

bmallick - the effect of the levcon is to keep the flow attached to the wing at higher a-o-a, thereby allowing it to stay in controlled flight with lower speed and effectively more of a nose up attitude. similarly during take offs, the ability to achieve higher a-o-a is a bonus. to compensate for the nose up attitude during carrier landings (steeper descent path than airfield landings), the nose angle is lowered structurally (permanently) so that the pilot can see over it. the use of slats/slots/lerx/levcon/blowing/vortex generating strips is a design optimisaton choice to keep the boundary layer smooth and the flow attached to the main wing. if the flow detaches from the wing, then you rapidly move into a high drag low lift situation - i.e. you start to drop out of the sky

to my knowledge, no naval aircraft have been fitted with concorde style moveable noses - the weight penalty is usually too great

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Re: LCA News and Discussions

Postby Indranil » 01 Jul 2013 14:32

nileshjr wrote:
Agreed. Only thing from my side, it can't be called "Cranked arrow delta" (because it does not have that characteristic "kink" at TE, which gives the distictive arrow tip shape).

Yes cranked arrow is definitely wrong. I typed it in a hurry.

nileshjr wrote:
Some more doubts:
1. when we say "wing is twisted" (wash in/out), about which axis the wing sections are turned actually?? For ex: if i rotate inboard sections w.r.t. axis passing through TE, I will end up getting twist + anhedral both (like in LCA). This can't be pure twist. Then which axis should it be. I can think of two natural options: About mid points of those sections or the aerodynamics center of thoseperticular sections??


In the classical washout the AoA of the aerofoil decreases along the span. This allows the wing root to stall before the wing tip thus allowing some allowance before the whole wing stalls. This also lowers lift near the wingtips, and hence lowers induced drag. In many modern wings you will have a wash-in followed by a washout. This is better for maximum lift being developed at the center of the wing. The axis is varied by different designers, but a common candidate is the aerodynamic center.

For LCA it is not a classical washout. The camber of the wing itself changes along the wing span. Thus creating the washout.

nileshjr wrote:
2. B Harry's article says (pg 85):
Two hollow spill ducts, next to leading edge, connect with the intake splitter and act as suction system for boundary layer/vortex control and reducing skin friction drag

I thought they act more like Blowing/Injection system and they blow air coming from intake splitters onto the root section of the wing to energige it and also enhancing LE vortex structure. How can it act as suction system? What am I missing here?

It acts as both. Harry was describing the entire phenomenon. When air goes from the splitter plate through the spill duct over the wing it creates a vortex behind the spill duct (much like a blowing system). According to Bernoulli, the turbulent flow in the vortex is at lower pressure. This energizes the airflow over the wing and allows it to stay attached to the wing for longer along with working as a suction for the boundary layer at the splitter plate.

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Re: LCA News and Discussions

Postby Indranil » 01 Jul 2013 14:48

bmallick wrote:Based on all the discussion going no with regards to Levcon's and whatever little I could read and understand on the internet and various papers, I have a few question for the guru's here.

a. Is it possible to deflect the Levcon's both upwards as well as downwards.

Not all levcons. But NLCA's LEVcon can be deflected at 30 degrees in the upward direction.
bmallick wrote:b. Let us say that the aircraft is at a AOA of 15 degree and the Levcon's are deflected downwards at an angle of 10 degree, in this the actual AOA of the levcon would be 5 degree. Does this lower the effective AOA of the wing, thus allowing the wing to operate to much higher actual AOA?How does this affect the flow over the wing?

The AoA of the Levcon is 5 degrees, but the AoA of the wing is 15 degrees. It is just that the flow over the wing will stay attached for longer. Hence you could take the wing to higher AoA.

bmallick wrote:c. Let us say that the aircraft is at a AOA of 5 degree and the Levcon's are deflected upwards at an angle of 10 degree, in this the actual AOA of the levcon would be 15 degree. Does this mean the levcon's which are at high AOA start generating vortex much earlier than in the case of a LERX? Does this allow the aircraft to go slower at the same AOA?

The phenomenon is what you describe but the effect is not. The levcons deflected upwards increase the lift slightly, but greatly increase drag. It is useful for slowing down the aircraft, but not to fly slowly. To fly slowly, you would have to generate the same amount of lift while flying slowly. The only way to do it with a fixed wing aircraft is to use flaps or to increase the AoA. To increase the AoA of the wing, you would rather deflect the Levcon down.

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Re: LCA News and Discussions

Postby bmallick » 01 Jul 2013 15:28

So basically Indranil what you are saying for case c is that the upward deflection would result in greater drag...basically as in case of a higher AOA wing. Basically a bigger effective flat surface against the direction of movement, hence greater drag.

So for higher lift, rather than increasing the AOA of the entire wing, just deflect the levcon higher, a much smaller surface at higher AOA, hence lesser drag. Is my understanding right?

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Re: LCA News and Discussions

Postby Lalmohan » 01 Jul 2013 15:30

i think the levcon gets you higher aoa for the whole wing - but does it at lower drag since the flow remains attached

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Re: LCA News and Discussions

Postby Indranil » 01 Jul 2013 15:50

bmallick wrote:So basically Indranil what you are saying for case c is that the upward deflection would result in greater drag...basically as in case of a higher AOA wing. Basically a bigger effective flat surface against the direction of movement, hence greater drag.

So for higher lift, rather than increasing the AOA of the entire wing, just deflect the levcon higher, a much smaller surface at higher AOA, hence lesser drag. Is my understanding right?

No. If you raise the levcon, it will start acting like a airbrake. It will increase drag much more than the small increase in lift.
Lalmohan wrote:i think the levcon gets you higher aoa for the whole wing - but does it at lower drag since the flow remains attached

Good question. IMHO, this will be very difficult to answer without wind-tunnel studies. Yes the laminar flow will always have lower drag. But near the trailing edge it is hardly so, especially at high AoA. It is highly non-linear system there.

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Re: LCA News and Discussions

Postby Lalmohan » 01 Jul 2013 15:52

agreed - however it is probably *far more effective* at *slightly high a-o-a* - which is what you'd need for naval landing scenarios

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Re: LCA News and Discussions

Postby JayS » 01 Jul 2013 16:16

indranilroy wrote:Yes cranked arrow is definitely wrong. I typed it in a hurry.



In the classical washout the AoA of the aerofoil decreases along the span. This allows the wing root to stall before the wing tip thus allowing some allowance before the whole wing stalls. This also lowers lift near the wingtips, and hence lowers induced drag. In many modern wings you will have a wash-in followed by a washout. This is better for maximum lift being developed at the center of the wing. The axis is varied by different designers, but a common candidate is the aerodynamic center.

For LCA it is not a classical washout. The camber of the wing itself changes along the wing span. Thus creating the washout.


It acts as both. Harry was describing the entire phenomenon. When air goes from the splitter plate through the spill duct over the wing it creates a vortex behind the spill duct (much like a blowing system). According to Bernoulli, the turbulent flow in the vortex is at lower pressure. This energizes the airflow over the wing and allows it to stay attached to the wing for longer along with working as a suction for the boundary layer at the splitter plate.



Ohh..its BL from the intake. I thought BL on the wings. Thats why the Kanfujan... :mrgreen:

A little bit of semantics again (sorry couldn't resists): What does the "Cranked' refer to exactly when we say "Cranked Delta" or "Cranked Arrow Delta"?? Change in dihedral angle in spanwise direction or change in LE sweep in spanwise direction??

Just want to clarify this. I have seen "Cranked Delta" referring to both type of wings by various authors. In fact, F-16XL which has Cranked Arrow delta wing, has no dihedral angle at all..!! Only conclusion I could draw from my lit survey is, it can refer to both types.

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Re: LCA News and Discussions

Postby nits » 01 Jul 2013 16:30

Production Lca Tejas aircraft all set for roll out

According to sources close to idrw.org, first two Production aircrafts of Countries indigenous fighter aircraft Program will be ready soon; both SP-1 and SP-2 are almost ready and will be handed over to IAF once IOC-2 is achieved by Tejas aircrafts.

First Production aircraft is one year behind schedule, but it was told to idrw.org that delays were not due to production issues but due to Tejas Project not achieving IOC-2 standard, aircrafts were built at a slower rate, IAF ordered 20 Tejas MK-1 aircrafts based on IOC-2 Configurations and it was unlikely that IAF could have accepted Production aircrafts without Tejas Project achieving IOC-2.

Defence minister and DRDO chief have promised IOC-2 for Tejas will be achieved by end of this year and Production aircrafts will be handed over to Indian air force at the same time , DRDO and HAL are also trying to deliver two more Production aircrafts by mid of next year .

DRDO is also planning to rollout first prototype of Tejas MK-2 by mid of next year and first flight by end of next year, they are also plans to put Naval Tejas back in air soon, aircraft has been going through intensive changes to its landing gear and undercarriage and will be shifted to Ins Hansa base in Goa for further testing, single seater variant of Naval Tejas is also likely be ready by end of this year.

IAF has placed orders for 20 IOC-2 Tejas MK-1 and 20 FOC Tejas MK-1, while Navy has placed orders for 8 Naval Tejas based on MK-1 configuration but will be ordering up to 40 Naval Tejas MK-2 for carrier operations, while IAF is looking forward to induct more than 80 aircrafts based on Tejas MK-2 but the follow up order will grow to 150 as per sources.
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Re: LCA News and Discussions

Postby nits » 01 Jul 2013 16:33

something which i didn't get in above article... it says first two aircrafts are ready and we just need IOC -2 for delivery... but i believe in gear up to get IOC - 2 there may be minor changes to achieve multiple parameters of IOC 2 and if we say first 2 production aircarft are ready - will they deliver it after making those required changes or they will come from SP3 onwards?

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Re: LCA News and Discussions

Postby Indranil » 01 Jul 2013 17:01

Lalmohan wrote:agreed - however it is probably *far more effective* at *slightly high a-o-a* - which is what you'd need for naval landing scenarios

yes.
nileshjr wrote:What does the "Cranked' refer to exactly when we say "Cranked Delta" or "Cranked Arrow Delta"?? Change in dihedral angle in spanwise direction or change in LE sweep in spanwise direction??
...
Only conclusion I could draw from my lit survey is, it can refer to both types.

I think so too. But more often than not, it is used for the crank in the LE.
nits wrote:something which i didn't get in above article... it says first two aircrafts are ready and we just need IOC -2 for delivery... but i believe in gear up to get IOC - 2 there may be minor changes to achieve multiple parameters of IOC 2 and if we say first 2 production aircarft are ready - will they deliver it after making those required changes or they will come from SP3 onwards?

Don't worry. If fully manufactured LSPs can be changed before IOC2, so can almost manufactured SPs. IMHO, they will not have many major changes left by now.

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Re: LCA News and Discussions

Postby mody » 01 Jul 2013 17:25

nits wrote:something which i didn't get in above article... it says first two aircrafts are ready and we just need IOC -2 for delivery... but i believe in gear up to get IOC - 2 there may be minor changes to achieve multiple parameters of IOC 2 and if we say first 2 production aircarft are ready - will they deliver it after making those required changes or they will come from SP3 onwards?


I wouldn't worry too much about this. LSP8 itself is supposed to be the final config aircraft for IOC2. There may be minor changes to be made, based on the current testing that is going on. However, its not like the SP1 and SP2 planes will be handed over to IAF, the very next day that IOC-2 is achieved. The required changes will be incorporated and then the planes will be flying with IAF.
Given IOC-2's supposed target date of September to November 2013, one can assume that by End of this year, IAF will have its hands on SP1 and SP2.

From the article what I am more worried about is that it states that by mid-next year DRDO-HAL will try to give two more SP aircrafts to IAF. Why only 2? Why not 4!!. If the initial production target is for 8 planes per year, they ought to deliver atleast 4 by mid next year and then another 4 by end of next year. Given that HAL is stating that SP1 and SP2 are almost ready, 6-7 months to deliver SP3 and SP4 is not a good rate.

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Re: LCA News and Discussions

Postby JayS » 01 Jul 2013 17:33

Lalmohan wrote:i think the levcon gets you higher aoa for the whole wing - but does it at lower drag since the flow remains attached


Two things:
1. Can the wing reach required coeff. of Lift (Cl) at all without Levcon?? Whatever may be the drag..(L = Cl * 0.5 * rho * velocity^2. you fix max landing speed which will tell you required Cl)
2. If it can, is the drag too much to handle?? (I think, in general, during landing, the a/c will typically be quite light as most of the fuel be used up so good enough thrust will be available to handle some increase in drag like 10%, 20% etc).

Our aim is to achieve highest possible Cl rather than highest possible AoA. Levcon can simply increase Cl at same AoA thereby achieving required Cl at less than max possible AoA (slope of Cl vs AoA curve changed at higher AoA region and stall AoA may or may not be increased, Just like flaps do). Or it can increase the AoA range of wing without affecting Cl at given AoA i.e no change in slope of Cl vs AoA curve but stall AoA is increased like slats/slots. (See Gurneesh's post above)

If answer to both above question is No, we think of using Levcon. So Levcons should enable the wing to achieve required high Cl value. Whatever may be the AoA at which it is achieved. If it lowers drag, well and good. If there is reasonable increase in drag lets take the penalty. As indranil said its difficult to make any statement regarding drag without looking into wind tunnel test results.


I want to know how exactly LEVCON act in NLCA. Keeping in mind, Gurneesh's post, whether levcons increase lift at same AoA (like flaps) or they simply extend the AoA range for the wing (like slat)??

My take, it works like flaps (albeit on different principle). It increases total Cl at given AoA (in higher AoA range only). Total Cl = normal Cl + vortex induced Cl.
Levcons does not increase the stalling/critical AoA. It should also increase stall AoA but it wouldn't be as effective as a slat.

Gurus please enlighten...
Last edited by JayS on 01 Jul 2013 21:16, edited 1 time in total.

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Re: LCA News and Discussions

Postby SaiK » 01 Jul 2013 18:28

I think LEVCON vs Canards discussions would have more value to the thread, rather against LERX. JMT

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Re: LCA News and Discussions

Postby Lalmohan » 01 Jul 2013 18:53

a levcon is somewhere between a slat and a canard but is more like a slat than a canard - its a lerx++
its utility is in keeping the flow attached to the wing during high a-o-a

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Re: LCA News and Discussions

Postby member_26965 » 01 Jul 2013 18:59

SaiK,

Canards can develop vortex too.

We will hear more on LEVCON's as UAV's have started maturing. They will not have much G problems.

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Re: LCA News and Discussions

Postby SaiK » 01 Jul 2013 19:08

I was thinking.. how much of movable aspects (degree/angle) for pitch corrections, shape and size of the fillet/lerx tending towards being a levcon, and how much of wing shape takes to become a canard.

these of course my laid-main understanding, to various of these attachment avatars. for example, if i may call pak-fa is more a canard than levcon? perhaps all depends on the function it was designed for, leaving the vortex aside as something the design handles or uses.

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Re: LCA News and Discussions

Postby Lalmohan » 01 Jul 2013 19:15

does anyone know the range of movement of the levcon? i am assuming that it deploys during landing phase to its required position (or it may be dynamically controlled to balance - but i would have thought that that is excessive given that its for the landing phase only) and then retracts during normal flight regimes into its 'hard' position

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Re: LCA News and Discussions

Postby Lalmohan » 01 Jul 2013 20:06

damn, i was looking forward to hearing about how fog generates vortices!!

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Re: LCA News and Discussions

Postby fanne » 01 Jul 2013 20:08

I wish the alacrity that LCA team is showing now, they would have showed before in the program, we may have had few SQ in service!! Now that the bar has been raised and LCA team can deliver, this should be the new normal. The only joker in the pack here now is HAL, they have to get out that this is not our product (it is ADA’s) and hence lesser priority. Heave off another company just for LCA ( that will then take up other indigenous programs once LCA 1and 2 matures) if that is what it takes. The model of ADA as designer and HAL as manufacturer is here to stay (even with AMCA) and we cannot afford a reluctant HAL.

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Re: LCA News and Discussions

Postby SaiK » 01 Jul 2013 20:16

fanne, a better model is periodic babooze specific introspection and risk management activities - say every 3 months status update could reveal more pressure points coming up to the higher levels much earlier in the life cycle, and automatically things will get adapt to better schedule slippage and identifying road blocks ahead.

i think, this is a program management issue. rather than identifying problems at user acceptance stage, it is better to find problems at requirements, design and integration stages.

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Re: LCA News and Discussions

Postby fanne » 01 Jul 2013 20:26

The problem here is not some mgmt mumbo Jumbo but a simpler one (that applies to everything in life) - of intent and passion. What LCA means to ADA as org (in general) does not mean the same for HAL (in general). If you want to see what HAL lacks for ADA, see what extra HAL ALH team has. Where there is a will there is a way- was true then and is true now.
rgds,
fanne
PS - what stops HAL from giving SP1 and SP2 to IAF and then after IOC-2 have another upgrade? (Full 1 year ahead). Babugiri? Or LCA being an 'orphan' child for HAL.

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Re: LCA News and Discussions

Postby Sagar G » 01 Jul 2013 20:39

fanne wrote:PS - what stops HAL from giving SP1 and SP2 to IAF and then after IOC-2 have another upgrade? (Full 1 year ahead). Babugiri? Or LCA being an 'orphan' child for HAL.


How is HAL supposed to do that without the consent of the design agency i.e. ADA ??? Also is IAF ready to take possession of SP-1 and SP-2 before IOC-2 ???

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Re: LCA News and Discussions

Postby SaiK » 01 Jul 2013 22:01

yes.. these type of issues are exactly what babooze can resort ahead in times. roll them in, slash their heads for non-performance, and let the tech community focus on their jobs. We need higher quality flux at top than bottom. For the bottom, give them more funds and oppty.

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Re: LCA News and Discussions

Postby Vipul » 02 Jul 2013 19:58

'Tejas' to be ready by 2014: DRDO chief

The first of the indigenous Light Combat Aircraft (LCA) 'Tejas' being developed for the Indian Air Force is expected to roll out by the end of this year or beginning of 2014 as the Defence Research and Development Organisation (DRDO) has put the project on the fast track, Avinash Chander, scientific advisor to the defence minister and secretary of the department of defence research & development, said here on Monday.

Chander, who was also appointed director general of DRDO last month, told TOI that Tejas has flown 62 sorties in June this year and should get IOC-2 (initial operational clearance) by the end of September if "weather permits". "We are endeavoring to get the clearance for production by 2014 beginning," said Chander, who was in town for a function organized by the Federation of Andhra Pradesh Small Industries Associations to felicitate DRDO scientists.

He also disclosed that more trials need to be carried out for the Ballistic Missile Defence (BMD) system being spearheaded by DRDO with respect to both 'endo' and 'exo' atmospheric interception capabilities and one such trial was slated for September. Saying that the assessment for the readiness of the BMD for deployment would be carried out by 2014 end, Chander said currently radars were being prepared for integration with the BMD. Though the project has long been viewed with scepticism, the DRDO chief said the BMD, a two-tiered system comprising two interceptor missiles for high and low altitude interception, would be deployed first in Delhi followed by one more city and finally some key cities across the country.

Meanwhile, G Satheesh Reddy, director of Hyderabad-based Research Centre Imarat (RCI) of DRDO said miniaturized avionics that provide all avionics systems including navigation, telemetry and mission computers on a single module is in the pipeline. He said this would not only reduce power consumption but would also weigh less without compromising on accuracies. Meanwhile, RCI is focusing on production of Infra Red and Radio Frequency seekers in addition to Micro Electro Mechanical System (MEMS) and Nano Electro Mechanical (NEMS) based sensors.


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