LCA Tejas: News and Discussions

mody · Post by **mody** » 17 Aug 2016 15:29

Rahulji any update whether OBOGS system will be part of MK1A or not?

uddu · Post by **uddu** » 17 Aug 2016 16:40

rahulm wrote:Weight s(h)aving: There is an ongoing discussion about saving weight by removing the droque chute in a naval aircraft equipped with an arrestor hook versus retaining it as a back up. Pilots, naturally, prefer to retain it.

Thank you for the details. Now Is it safe to have a chute while landing on an aircraft carrier? What if the hook is missed and the chute is opens accidentally. Will it not affect the normal way of accelerating in full power to again get airborne?

Sid · Post by **Sid** » 17 Aug 2016 17:15

uddu wrote:
rahulm wrote:Weight s(h)aving: There is an ongoing discussion about saving weight by removing the droque chute in a naval aircraft equipped with an arrestor hook versus retaining it as a back up. Pilots, naturally, prefer to retain it.
Thank you for the details. Now Is it safe to have a chute while landing on an aircraft carrier? What if the hook is missed and the chute is opens accidentally. Will it not affect the normal way of accelerating in full power to again get airborne?

Chutes will be used when they are landing on airfields. A lack of chute may reduce the number of landing strips which they can use.

shiv · Post by **shiv** » 17 Aug 2016 17:29

I am not sure that in service naval aircraft have chutes. However the NLCA under testing will do 90% of its flying from land - so a chute will help preserve the brake and reduce landing distance in emergency. Just a guess

dkhare · Post by **dkhare** » 17 Aug 2016 22:20

Good morning all. Great to have BRF online again. Thank you for all the work done in the restoration.

I don't know of any western naval aircraft that have a drogue chute as part of the design but I wonder if the Russian MiG 29Ks and Su 33 retain their chutes. However, if the pilots want it - it means that it increases the number of airfields closer to the shore that they can use during operations and emergency situations. I don't think the drogue chutes will ever be used during carrier operations.

Looking forward to part 2 of the report...

Indranil · Post by **Indranil** » 17 Aug 2016 23:15

I think Hakim is right on this one. They are talking of chutes on the test platforms or not.

Having a chute while landing on deck increases risk by increasing landing weight.

rahulm wrote: Actual flight testing data including HD visuals from GoPro cameras installed has revealed turbulent flow which was overlayed with the flight regime.

It was discovered that in certain turbulence regimes, the air brake was fluttering/deploying leading to undesirable handling during certain flight regimes. The solution was to a) treat the air brake as a control surface and modify the control laws accordingly and b) create a different wing geometry for landing which when combined with the air brake deployment solved the fluttering and pitch up issue.

CFD analysis did not predict this behaviour.

There were papers of how the brakes were not as effective as required at some flight regimes, and that it causes an involuntary pitch up moment thanks to its position. However, I had no idea about this flutter/deploying part. Would love to know a little more about the solution (if you can). More slat deflections for increasing untrimmed drag?

rahulm wrote: A great illustration that there are no short cuts in testing and no amount of TOT or deep TOT will ever provide us such vital data. When we own the IP we have the expertise and capability to investigate and resolve issues.

Absolutely.

rahulm wrote: MODS please edit and delete any and all parts at will if you feel so inclined.

You have crossed no line. Please continue to post with discretion.

Cybaru · Post by **Cybaru** » 18 Aug 2016 02:49

Rahulm ji,

How much are they going to expand internal fuel? What are they thinking? between 3000-4000 kgs or higher number? Any talk of CFT?

shiv · Post by **shiv** » 18 Aug 2016 09:49

rahulm wrote:Typed from BLR airport. Here is Part 1

I have to board now so will type part 2 later in which I will,cover arrestor hook, radome, missile racks and radar.

Gosh that's one heckuva long flight you're on.

Kashi · Post by **Kashi** » 18 Aug 2016 11:30

rahulm wrote:A great illustration that there are no short cuts in testing and no amount of TOT or deep TOT will ever provide us such vital data. When we own the IP we have the expertise and capability to investigate and resolve issues.
...
There is a general feeling that even one accident or major incident will lead to program abandonment. Hence, the grinding path which annoys many jingos.

Illuminating and scary at the same time. To foster and grow the in house know how, we need to persist, design, test, refine, redesign if necessary and test again.

But the fear of failure that one major failure will bring it all to a nought is highly concerning. Perhaps the folks involved are aware that there are many who do not wish to see the programme succeed. They will try every trick in the book to scuttle the project, sabotage cannot be ruled out.

But there's a another concern, the fear of failure means that the developers and the design team will opt for safety above all. If it comes down to choosing between a safe but probably of limited utility in enhancing the performance vs something more radical, more risky but promises a quantum leap in performance, the developers may choose to go for the less performing safer option, since the cost of failure has been set too high. Over the time this forces the programme into a longer development trajectory as the designers look for solutions that are guaranteed to be safe and yet offer a great leap forward in performance.

This is where the government or senior honchos need to step in and assure the team that a setback is merely that a setback, this is will not way impact the future of the programme and its rightful place in IAF and IN inventory.

rahulm · Post by **rahulm** » 18 Aug 2016 11:50

Sorry for the delay. I spend too much unnecessary time in sarkari offices in Goa to sort out some matters. It's a den of vice, sloth and inefficiency in a BJP governed state.

This is because I won't bribe these suckers and NaMo wants us to return - to what? These blood sucking parasites.. Ok enough ranting.

First things first - no 'ji' for me please. Rahul is fine. I have never been comfortable with this reverence. Thank you.

Here is Part 2

Arrestor hook: The arrestor hook is a complete desi design by ARDC and is being integrated into NP2 (and NP1).its looks like a neat hefty device. The hook is manufactured, assembled and ready to install.

Some reading material I found from a HAL patent (ARRETOR sic HOOK ACTUATION SYSTEM FOR NAVY AIRCRAFT page 26236) http://www.ipindia.nic.in/ipr/patent/jo ... art_ii.pdf There are other HAL patents which can provide some insight for the very committed. The doc is very long.

NP2 was structurally designed for the arrestor hook, whereas, initially there was no plan to fit the hook to NP1. This has now changed. NP1 is undergoing structural mods to fit the arrestor hook.

NP2 has dedicated mount points for the hook. A fairing will cover the assembly except the hook. However, the plane is likely to look quite different with this “appendage”

After hook installatIon, the CLAW will be made ‘aware’ of the hook and a series of graduated tests will be undertaken; starting with taxi trials with a combination of various hook positions at various ground speeds.

Next, NP2 will move to the SBTF to check hook wire catch starting at low speeds and then moving progressively to higher speeds. Drag characteristics and wear of hook when it's scrapes the deck will be measur d. Various parameters including wire tensions, loads on wire, hook assembly and fuselage will be measured.

The hook, at some stage will be destructively tested.

Hook assembly to NP2 is imminent - a few weeks away. We could see hook taxi trials by October this year and SBTF trials by Feb/March 2017 if all goes to plan. This will be followed by an arrested landing at the SBTF which would be a significant milestone. If all goes well, we could be doing a synchronised BRF lungi dance sometime next year.

The aircraft with hook would also be subjected to wake trials by having it approach our steaming carrier to observe flight characteristics at typical landing approach profiles, starting obviously from higher altitudes and then progressively getting closer, eventually culminating in a touch and go. This part, obviously, is still a fair way ahead.

The current version of the hook has a powered lock and deploy position. There, is no gravity assisted deploy option yet but is planned in the next version.

@indranail you are on the right track in relation to the solution. I don't want to get specific except to say that it's a particular configuration comprising the air brake, levcons and elevons. I, will, however note that this problem involved too many complex variables and it's a testament to our maligned SDRE Institutions that they could solve for this and resolve without any foreign assistance.

Did not discuss OBOG and CFT. Ran out of time.

I will write a separate part on project organisation aka red tape.

sankum · Post by **sankum** » 18 Aug 2016 15:07

RahulM, thanks for the valuable insight.

Will Nlca mk1 see service on carrier in AD role if MTOW from skijump is above 14T and possible payload of 3T?

arunsrinivasan · Post by **arunsrinivasan** » 18 Aug 2016 15:47

RahulM, Many thanks for this.

You had also promised updates on "radome, missile racks and radar" is that in the next installment?

Kartik · Post by **Kartik** » 18 Aug 2016 22:43

Thanks Rahulm for the good insights.

Regarding the point you made on the arrestor hook not having a gravity assisted deploy option, the link you posted itself states this-

All fighter aircraft which are operated on the ship are required to land on deck and these aircraft are equipped with a very reliable and fail safe arrestor hook system for landing safely.

This schematic design is very reliable and also caters for fail safe design. The normal operation is achieved by a three positions selector which is Hook UP, Hook Down and Emrg Hook Down. Other then normal operation a fail safe design for the condition of electro selector stuck/failed in retracted position is taken care by providing a bypass restrictor on the normal system which will help in allowing the hydraulic fluid in the jack to return line and allow the hook to extend down.

So there doesn't seem to be any need for a gravity assisted deploy option as such.

Indranil · Post by **Indranil** » 18 Aug 2016 23:45

rahulm wrote: @indranil you are on the right track in relation to the solution. I don't want to get specific except to say that it's a particular configuration comprising the air brake, levcons and elevons.

Oh! I did not realize that you were speaking about NLCA's specifically. With the LEVCONs, there are a few theories swirling in my mind. Will you be able to take this conversation offline? Please say NO, if you can't. Nothing changes if a jingo's intellectual curiosity remains unfulfilled.

SaiK · Post by **SaiK** » 20 Aug 2016 04:31

this news article happened when we crashed.

http://www.newindianexpress.com/nation/ ... 517883.ece
HAL must be modernised, if Tejas are to be saved: Admiral Arun Prakash

Chinmay · Post by **Chinmay** » 21 Aug 2016 17:58

http://www.tribuneindia.com/news/nation ... 83353.html

The headline says LCA manufacturing facility to be set up in AP. But the article makes some odd statements like

weapons integration facility to manufacture Light Combat Aircraft

and

Wem Technologies Private Limited is partnering with Lockheed Martin, the largest defence equipment manufacturer in the US, to set up this facility

Since when is LM involved in LCA setup? Or is it just DDMitis?

JayS · Post by **JayS** » 21 Aug 2016 19:39

Thanks a lot Rahul for the excellent posts. Its good to be back here at BRF. If possible could you please clarify what exactly you meant by this??

It was discovered that in certain turbulence regimes, the air brake was fluttering/deploying leading to undesirable handling during certain flight regimes. The solution was to a) treat the air brake as a control surface and modify the control laws accordingly and b) create a different wing geometry for landing which when combined with the air brake deployment solved the fluttering and pitch up issue.

Was it that when Air breaks get deployed they flutter or cause the wing to flutter in certain regimes?? Or was it that in certain regimes (vortex burst I am guessing) air breaks starts fluttering or get deployed on without them being actuated??

I am bit confused here. If you think its too mch to disclose on public forum, you can just ignore the question.

rahulm · Post by **rahulm** » 21 Aug 2016 22:39

Sorry all. No internet in my part of Goa for last 3 days. Despite my optimism, sometimes, I wonder about this smart city business without a decent reliable internet.vidhyut dept chopped a few trees and broadband cable as a bonus. Lots of coconut here though and plenty of high decibel bhajans due to impending chaturti.

Have time for a quick post.

@indranail maybe let selling dogs lie for a while. Best to be prudent. Hope, you understand. You are on the right track

@Kartik it would seem so from the patent. That's a designers POV. Pilots have different ideas, rightly or wrongly, and they have final say on test flight confIguration and sign off. Time will tell.

@JayS deployment without actuation.

JayS · Post by **JayS** » 22 Aug 2016 00:33

^^ Thanks RahulM for clarification.

Indranil, your solution is more plausible in this scenario. I was on wrong track.

SaiK · Post by **SaiK** » 22 Aug 2016 02:10

http://www.dnaindia.com/india/report-li ... sh-2247487

confusing.. why Wem-Lockheed Martin setting up facilities for weapons integration of LCA?

Indranil · Post by **Indranil** » 22 Aug 2016 04:55

rahulm wrote: @indranail maybe let selling dogs lie for a while. Best to be prudent. Hope, you understand. You are on the right track

Absolutely fine. Enjoy the coconut and bhajans.

rahulm · Post by **rahulm** » 22 Aug 2016 07:35

Part 3

Hard point racks: the inboard racks are big. I did not realise just how big they are until I saw them. They pack a heft. The reason is - wait for it - all racks are rated to pull 8 G's with a fully loaded external tank. Since parts commonality was a goal to reduce inventory we have this situation.

Again, this was a designers view. The pilots POV is that if 8Gs have to be pulled with a fully loaded tank, they have a much bigger issue on their plate and the tank will be the first to go. In a war scenario, pilots will be keen to use up fuel in the external tank first, jettison and then more to internal fuel.

Pilots feel, at most 1 hard point, perhaps, the centre line point can be rated for 8Gs. The good news is that sleeker racks are on their way but for now,other test points are a higher priority.

The good news is that Tejas is being honed for the end user.

AoA:treading carefully here. Firstly, current engine has enough thrust for max design AoA in certain config. This means we don't need Mk2 to complete AoA test points except for the configs possible only with the uprated engine. The 1 deg AoA = X knots wind relationship for wing design is well known. Therefore, the IN is particularly interested in achieving design AoA asap for carrier ops.

NLCA MK1 orders: The IN is keen to start pilot familiarisation and training as soon as practicable. We should see an order for about half a sqn worth once arrestor hook and a few other test points are covered. This might warm some jingos hearts.

Gagan · Post by **Gagan** » 22 Aug 2016 07:51

The pilots want to retain the chutes on the planes because they do have to land on terra firma quite a lot. The tail hook is quite useless when landing back on home airbase off of the carrier

wig · Post by **wig** » 22 Aug 2016 09:41

http://timesofindia.indiatimes.com/city ... 793983.cms

BHEL developing new types of compact heat exchangers for LCA

BHEL-HPVP (Bharat Heavy Electricals Limited - Heavy Plates and Vessels Plant) is engaged in indigenous development of new types of compact heat exchangers (CHEs) for the Light Combat Aircraft, also known as Tejas.
According to BHEL-HPVP sources, the research and development department at the plant is currently engaged in indigenous development of four new types of CHEs for the Mk2 version of the Tejas aircraft (LCA-Mk2).
Sources said BHEL-HPVP will be supplying 40 of these new CHEs under a project for the Aeronautical Development Agency (ADA), Bangalore, a DRDO agency. This will be in continuation to the earlier CHEs supplied for the LCA. Official sources said Hindustan Aeronautics Ltd (HAL), Bangalore, has recently inquired with HPVP for supply of a further 100 sets of Tejas heat exchangers. Also, sources said the Indian Navy is planning to order another 40 sets of Tejas heat exchangers in the coming years.
Including those supplied during the development stages, HPVP has so far supplied over 400 compact heat exchangers to ADA and HAL.
Recently, the Tejas were inducted into the Indian Air Force, fitted with compact heat exchangers supplied by BHEL-HPVP, which officials said is a landmark achievement for any indigenously developed item.
After completion of successful development of CHEs for Tejas, HPVP has manufactured and supplied over thirty aircraft sets of Tejas heat exchangers to ADA and HAL under their Limited Series Production (LSP) and Series Production (SP) programmes. CHEs supplied by HPVP are fitted on board every Tejas flown so far and have clocked several hundred hours of flight with consistently satisfactory performance.
The R&D department of BHEL-HPVP, has successfully developed eleven different types of compact heat exchangers indigenously for the Indian LCA. Starting from mid 1990s, these developments were carried out over a period of ten years under successive development contracts assigned to HPVP by the Aeronautical Development Agency (ADA).
Officials said these exchangers are both compact in size and light in weight, making them best suited for aeronautical use. They play the vital roles of maintaining a controlled environment for the pilot and preventing the hydraulic and lubricating oils in the aircraft from excessive heating during flight. Making of these heat exchangers requires high quality machining, vacuum brazing and welding technologies apart from design and engineering.
According to sources, the CHEs developed by HPVP for the Tejas have undergone and passed the severe pre-flight qualification tests mandated for any airborne equipment. On their successful qualification, these CHEs have been accorded the 'Type Approval' for use on board the Tejas by the air-worthiness authorities in ministry of defence. These heat exchangers have been developed and manufactured for the first time in the country at HPVP, who continue to be their sole suppliers in the country to this day. HPVP is thus counted among the select few firms worldwide with the capability to design and manufacture state-of-the-art heat exchange equipment of international quality for military aircraft.

Cosmo_R · Post by **Cosmo_R** » 22 Aug 2016 17:35

SaiK wrote:this news article happened when we crashed.

http://www.newindianexpress.com/nation/ ... 517883.ece
HAL must be modernised, if Tejas are to be saved: Admiral Arun Prakash

This sheds more light on how PSUs fucntion:

http://economictimes.indiatimes.com/new ... 715366.cms

Arun Prakash did not say this but others have (publicly) that the LCas they've seen are not interchangeable parts wise and that even the two to be delivered as part of the first squadron may be 'bespoke' with variations among them—making parts maintenance a nightmare.

Gagan · Post by **Gagan** » 22 Aug 2016 18:05

Don't the roosi Migs have some level of Jugaad in them all?
At some level it will be left to the base repair depot to do build small custom parts

srin · Post by **srin** » 22 Aug 2016 19:10

Gagan wrote:The pilots want to retain the chutes on the planes because they do have to land on terra firma quite a lot. The tail hook is quite useless when landing back on home airbase off of the carrier

If you see this video, they do an emergency landing of a CF-18 hornet of Canadian Air Force with arresting cable on an airfield. Normal landings (in the same Jetstream series) don't seem to require cables or chutes.

Aditya_V · Post by **Aditya_V** » 22 Aug 2016 19:30

Almost all USAF aircraft have an arrestor hook or tail hook which was is to catch a cable at end of the runway if the brakes failed, the IAF SU-30's use a large Net.

http://flyingwithfish.boardingarea.com/ ... tailhooks/

Tailhooks on military aircraft are a common sight … although we tend to only think of them as being part of aircraft landing on aircraft carriers, not those landing on runways. This Reader Mail comes from Damian Willis in the Great White North (aka: Canada) who asks, “I recently spent some time watching US Air Force F-16 Falcons and F-15 Eagles coming and going outside of Las Vegas and noticed what I thought were tailhooks mounted on them. Why do Air Force jets have tail hooks?”

Many U.S. Air Force runways have an emergency arresting cable hidden in a recess of the runway surface. Should an aircraft suffer a hydraulic problem, brake failure, or need to abort a take off on a short runway, among other potential situations, a pilot will call “cable, cable, cable,” alerting the tower to raise the arresting cable from its runway recess.

IAF uses Arrestor Barrier nets, may be we go for the USN and USAF system for the NLCA ground landings

http://www.drdo.gov.in/drdo/pub/techfoc ... restor.htm

Cosmo_R · Post by **Cosmo_R** » 22 Aug 2016 20:02

Gagan wrote:Don't the roosi Migs have some level of Jugaad in them all?
At some level it will be left to the base repair depot to do build small custom parts

Oh I'm sure they do. I suspect though that's what the IAF wants to get away from

disha · Post by **disha** » 22 Aug 2016 22:05

Have to quote in full with some highlights mine.,

rahulm wrote:Part 3

Hard point racks: the inboard racks are big. I did not realise just how big they are until I saw them. They pack a heft. The reason is - wait for it - all racks are rated to pull 8 G's with a fully loaded external tank. Since parts commonality was a goal to reduce inventory we have this situation.

Again, this was a designers view. The pilots POV is that if 8Gs have to be pulled with a fully loaded tank, they have a much bigger issue on their plate and the tank will be the first to go. In a war scenario, pilots will be keen to use up fuel in the external tank first, jettison and then more to internal fuel.

Pilots feel, at most 1 hard point, perhaps, the centre line point can be rated for 8Gs. The good news is that sleeker racks are on their way but for now,other test points are a higher priority.

The good news is that Tejas is being honed for the end user.

AoA:treading carefully here. Firstly, current engine has enough thrust for max design AoA in certain config. This means we don't need Mk2 to complete AoA test points except for the configs possible only with the uprated engine. The 1 deg AoA = X knots wind relationship for wing design is well known. Therefore, the IN is particularly interested in achieving design AoA asap for carrier ops.

NLCA MK1 orders: The IN is keen to start pilot familiarisation and training as soon as practicable. We should see an order for about half a sqn worth once arrestor hook and a few other test points are covered. This might warm some jingos hearts.

1. For the bolded part., I also felt that the racks are big - now we know the reason. Also it appears that in some parts LCA is over designed. And now it meets practicality. The initial design was from a manufacturer/integrator/maintenance point of view while the pilots came and provided their perspective. Glad that pilots POV won the day here. manuf/integrator/maintenance can take a hike if they complain about two many SKUs in this case. Making the racks appropriately sized will also result in weight s(h)aving.

2. The underline part, indeed warms up the NLCA followers., looks like NLCA is coming together as a test/"trainer" variant! Navy is using NLCA Mk1 to learn the design, test its ideas, implement changes and getting more user feedback and hopefully incorporate all of that into NLCA Mk2. If all this comes through., NLCA Mk2 will be a real formidable fighter!! Who would have thunk?

SaiK · Post by **SaiK** » 22 Aug 2016 22:06

http://www.thehindu.com/news/national/o ... 015837.ece
Tejas chief designer felicitated

disha · Post by **disha** » 22 Aug 2016 22:09

Cosmo_R wrote: This sheds more light on how PSUs fucntion:

http://economictimes.indiatimes.com/new ... 715366.cms

Arun Prakash did not say this but others have (publicly) that the LCas they've seen are not interchangeable parts wise and that even the two to be delivered as part of the first squadron may be 'bespoke' with variations among them—making parts maintenance a nightmare.

Initial runs., this is going to be normal. Air force now has a local homegrown fighter that can go into continuous improvement process. For example., Mk1.a - Mk1.b - Mk1.c etc has some improvement over the other. This creeping improvements when accumulated say in Mk1.n will show a more refined fighter than Mk1. IAF needs to understand that Tejas is its own IP (look at Navy NLCA for example) and they do not have to run to somebody else to suggest an improvement!

Of course lazy complaining about this or that not available or not fitting together is easy.

SaiK · Post by **SaiK** » 22 Aug 2016 22:13

http://timesofindia.indiatimes.com/city ... 793983.cms

So, the 400 CHEs for how many Mk1 s?

Indranil · Post by **Indranil** » 22 Aug 2016 23:10

Rahulm, people like you are the reason why BR is what it is. Thank you. This spiral refinement is most encouraging. I had two questions though.
1. The pilots' input that there is no practical need for inboard pylons to be 8G rated for full-fuel-tank load is abosultely logical. But wouldn't the outboard pylons need to be 8G capable? You don't want to lose your CCMs!
2. I have read about sleeker pylons for a while now. But those refinements were more for redesigned fairings for less drag. So, this is in addition to that. However, this begs a further question. If pylons were overdesigned to carry max load at 8G, so must have been the wing for all those hardpoints. If that requirement goes, the wing can be optimized down as well. I don't expect Mk1 or Mk1A wings to be reoptimized. The timelines will not allow for that. But, what about Mk2? Any talks on that?

One cannot underestimate the value of these lessons into designing the AMCA. Critical, absolutely critical.

JayS · Post by **JayS** » 23 Aug 2016 00:42

indranilroy wrote:Rahulm, people like you are the reason why BR is what it is. Thank you. This spiral refinement is most encouraging. I had two questions though.
1. The pilots' input that there is no practical need for inboard pylons to be 8G rated for full-fuel-tank load is abosultely logical. But wouldn't the outboard pylons need to be 8G capable? You don't want to lose your CCMs!
2. I have read about sleeker pylons for a while now. But those refinements were more for redesigned fairings for less drag. So, this is in addition to that. However, this begs a further question. If pylons were overdesigned to carry max load at 8G, so must have been the wing for all those hardpoints. If that requirement goes, the wing can be optimized down as well. I don't expect Mk1 or Mk1A wings to be reoptimized. The timelines will not allow for that. But, what about Mk2? Any talks on that?

One cannot underestimate the value of these lessons into designing the AMCA. Critical, absolutely critical.

1. I don't think CCMs count in here. The two CCM are part of clean config and as such those two wing tip stations would be always rated to highest G rating that the airframe is capable of. Its the other pylons which matter. Also even when pylons which are further from centerline are rated for <8G for max load they can still carry AAMs for 8G since AAMs are much lighter than usual bomb loads that those pylons can carry. So I think the AAM loads are covered well enough.

2. I wonder why would they go for this. Commonality seems pretty low-priority objectivity here, weight/drag begin the heightest. Also AFAIK there is a integrated team of ADA-HAL-IAF-MoD atleast since 2005. Then how such issues are still lingering?? Looking at such decisions perhaps its obvious why LCA went overweight. Though one more point to keep in might (not sure how relevant it is in LCA's case) that stores relieve wings from high lift loads and thus actually help wing structure to be less stiff and lighter. So we may not see all that huge weight saving in the wing structure itself- the wing redesign efforts may not be worth. But of coarse smaller pylons would help both weight wise and drag wise.

But hopefully they have learned now and user opinions would be considered right at the concept stage.

Indranil · Post by **Indranil** » 23 Aug 2016 01:28

JayS wrote:Though one more point to keep in might (not sure how relevant it is in LCA's case) that stores relieve wings from high lift loads and thus actually help wing structure to be less stiff and lighter.

Stiffness: yes. Strength: no. Lighter: I don't think so. If this was so, then hanging more weights from hardpoints would make wings lighter. Why would people not do so? It is a win-win.

I agree with you that the savings from redesigning the wing may not be greater than few 10s of kgs and may not worth be it.

JayS · Post by **JayS** » 23 Aug 2016 02:06

^^It does actually. That's one of the advantages of wing mounted engines in a airliner. It reduces bending moment at the root and thus you can make thinner section-ed and lighter wing. Its also helpful in reducing flutter. Why you don't have something always hung around on pylons?? Because that would also increase drag, fuel consumption etc etc. Military jets have different priorities. And thats my point, the wing is already designed for full 9G lift load with no weapons except CCM. Having weight hanging actually helps relieving this load as the store load in in opposite direction of lift load. So while there may be some saving in weight in local structure, as a whole the entire wing may not give much weight saving as such.

SaiK · Post by **SaiK** » 23 Aug 2016 02:59

So the design of the stores (reduced drag) can help in reaching 9G with it (within design limits)?

Indranil · Post by **Indranil** » 23 Aug 2016 05:37

JayS wrote:^^It does actually. That's one of the advantages of wing mounted engines in a airliner. It reduces bending moment at the root and thus you can make thinner section-ed and lighter wing. Its also helpful in reducing flutter. Why you don't have something always hung around on pylons?? Because that would also increase drag, fuel consumption etc etc. Military jets have different priorities. And thats my point, the wing is already designed for full 9G lift load with no weapons except CCM. Having weight hanging actually helps relieving this load as the store load in in opposite direction of lift load. So while there may be some saving in weight in local structure, as a whole the entire wing may not give much weight saving as such.

Question. Suppose I want to hang a heavier engine from the same wing, will the wing need strengthening or not? Consider only the weight of the engine.

Suresh S · Post by **Suresh S** » 23 Aug 2016 06:13

My ek so salaam to kota Harinarayan, the true hero of mother India. India will not become a great nation until and unless these true heroes are given the prominenece they deserve not the worthless junk that clutter the airwaves and media.Mother India will be forever grateful to you sir.