LCA News and Discussions, 22-Oct-2013

[Wickberg]

It might have something to do with the similarities. Two lightweight projects started at the same time (early 80s), single engined- even shares the same engine (kind of), none of them belonging to any of the classic super powers (USSR/USA) nor a European conglemorate. Considering all this it´s not hard to understand why they are beeing compared. The fact that the LCA and Gripen has gone totally different ways since the projects was started has offcourse changed this. But I remember just a few years ago most people on this board were still comparing the LCA to the Gripen and arguing how much superior the LCA was (is) and how it would dominate the export market, not to mention any fighter the Pakis or Chinese would show up. How times can change in a few years...

Lets catch up a decade from now and see if your lot even makes fighters..

Yeah, that would be great! The only problem is "my lot" has never made fighter airplanes. Gävle, Sweden, is more known to making ships, coffe, candy, paper-products and mobile-phones. And produce hockeyplayers to the NHL offcourse. If u mean Sweden per sake, or SAAB, I think we still will have a chance of that company producing fighter jets in 2025. They did close a deal with Brazil and SweAF to produce the Gripen E/F. My only wish is that LCA is not scrapped at that time and it would have reached operational status. I´m not certain of that but one can only hope!

[Indranil]

MODERATOR NOTE: STOP THIS

[SaiK]

My mango man thinking is production level issues also needed to be addressed ASAP. The reported private participation may be a game changer here. From what I gather there is a huge scope for LCA type light AC from the nations which are looking for a cheaper option to replace their Mig21 type ACs. Hence having a 40-60 AC manufacturing capacity may become a viable option if proper marketting etc is done. GE eng may be a problem for exports, but I am sure Khan will be willing to work with us to export this AC to its munnas at least. We ourselves need some good numbers so that LCA can take care most of the work in the west leaving other frontline ACs for North in a possible two front war.

well, you did not read latest info from DAC meetings
http://tarmak007.blogspot.com/

they have not taken LCA into considerations for private participation yet (for production). of course, there it is 100% possibility that those private already participated with LCA TD, PVs, are bound to be in!

I am waiting to hear the concurrent engineering setup HAL was planning to establish and earmarked space for this soon.

[Shreeman]

Meh or just good project management? Any lessons for the LCA Navy?

[member_28108]

There is an exhibition on National college grounds Bangalore by ISRO and DRDO got to talk with quite a few scientists there.Interesting.Ending on Saturday evening

[shiv]

Newly released HD video of the Ski Jump test - with more camera views and footage - Courtesy of the LCA Tejas Team

http://www.youtube.com/watch?v=dB73FdERNBA

Jagan Ji, this video is a celebration and needs to be appreciated with gusto.



Happy New Year to the LCA team. We really need FOC for the IAF version ASAP.

Interesting. Tarmak's blog has stills of the LCA before takeoff and it is in the place where you can see a hut. In the video the hut coincides with a yellow rectangular patch on the runway. Looks like the LCA Navy took off in a length of runway approximately equal to the length of a carrier.

[chackojoseph]

Interesting. Tarmak's blog has stills of the LCA before takeoff and it is in the place where you can see a hut. In the video the hut coincides with a yellow rectangular patch on the runway. Looks like the LCA Navy took off in a length of runway approximately equal to the length of a carrier.

Yes, it was short take off equivalent to the length of the carrier.

[shiv]

Interesting. Tarmak's blog has stills of the LCA before takeoff and it is in the place where you can see a hut. In the video the hut coincides with a yellow rectangular patch on the runway. Looks like the LCA Navy took off in a length of runway approximately equal to the length of a carrier.

Yes, it was short take off equivalent to the length of the carrier.

Was just surprised that they deliberately left out the initial part in all videos.

[chackojoseph]

Was just surprised that they deliberately left out the initial part in all videos.

No, there are two videos. The first one clearly shows it.

[member_28932]

Now Tejas is fine and flying. At this point of time we need to ask some simple questions. Whether Aircraft performs as design and whether it performs well with its counter parts such as Grippen, M2k etc.

Q is why should we compare Tejas to Grippen / M2k????
Neither are with our adversaries right now and will never be their choice, as pakis cannot afford it and chinese cannot accesss it.
Tejas needs to be evaluated against JF17 and Su27 & its copies with PLAAF.
That will be right comparo for it & how it overcomes them should be our focus

Simply because when we have any product in your hand , it is evaluated based on 2 criterion. 1) against what it was designed to and 2) How does it perform against its counterparts. That will give us ideas about the improvement of any product.

The argument that our adversary do not have it is meaningless. M2k is almost similar aircraft in terms of dimension and engine power. So compression is very much relevant. At least our new aircraft must match a decades old aircraft in performance.

[chackojoseph]

The argument that our adversary do not have it is meaningless. M2k is almost similar aircraft in terms of dimension and engine power. So compression is very much relevant. At least our new aircraft must match a decades old aircraft in performance.

It is not aircraft to aircraft comparison. it is about what IAF wants in it. They are getting almost everything they asked for in Mk II. M2K and Tejas have fundamental difference of size.

[Indranil]

Well, I looked at the Dabolim airport at wikimapia. According to my calculations it was a 300 mtr to 350 mtr run, much longer than what one gets on an aircraft carrier. But bear in mind:

1. The airport is stationary,
2. The wind was blowing down the runway at least 15 knots,
3. There were no restrainers, and
4. This was the first test, so probably Tejas was going faster than it needs to for safety margins (evidenced by the 11 degree climb instead of the 7 degrees).

[ritesh]

Might be old hat but why was the LCA not taken in after IOC? Why the need for FOC when even the euro fighter was inducted at does production level? Foc, ground attack, lgb capability were all done later. Same with meteor integration.

There is a standing order for 20 LCA @ IOC level. Of which first two will come, hopefully, by March 2015.

So, what's the angst against?

I suppose the numbers...100-200 sound so much better
I understand there are Qs about HAL's capacity to deliver those, but would have sent out strong message to import mafia

[Prasad]

Might be old hat but why was the LCA not taken in after IOC? Why the need for FOC when even the euro fighter was inducted at does production level? Foc, ground attack, lgb capability were all done later. Same with meteor integration.

There is a standing order for 20 LCA @ IOC level. Of which first two will come, hopefully, by March 2015.

So, what's the angst against?

No angst rohit. Just asking. So iaf will take 20 IOC mk1 and what else? 20 more foc mk1s before waiting for mk2 ioc and foc versions? Is that the plan?

[chackojoseph]

Prasad,

You are right on your point. FOC is achieved while in services. It is not necessary to wait for FOC to complete. In Europe they call it Trance. IAF is doing a mistake like it did for MKI. Unless LCA is flown for multiple hours in realtime conditions, we will not understand the issues. We will end up in figuring problem like we are experiencing in MKI.

[Shreeman]

Prasad,

You are right on your point. FOC is achieved while in services. It is not necessary to wait for FOC to complete. In Europe they call it Trance. IAF is doing a mistake like it did for MKI. Unless LCA is flown for multiple hours in realtime conditions, we will not understand the issues. We will end up in figuring problem like we are experiencing in MKI.

Chacko,

No, not trance. Much as I would like to see the mystic european dances -- not in a trance, I would not. Lets call it tranche and dig our way below pakistan all the way to eyeran.

[SanjayC]

Simply because when we have any product in your hand , it is evaluated based on 2 criterion. 1) against what it was designed to and 2) How does it perform against its counterparts. That will give us ideas about the improvement of any product. The argument that our adversary do not have it is meaningless. M2k is almost similar aircraft in terms of dimension and engine power. So compression is very much relevant. At least our new aircraft must match a decades old aircraft in performance.

Bad logic that is a recipe for a never-ending wild goose chase (IAF is cleverly using this logic to reject or delay India-made products). It is commonsensical and much better to benchmark a weapon system against what it will be realistically fielded against if a war breaks out. If it is better than that, deploy it -- don't just keep comparing it to weapon systems from much more advanced (but irrelevant for us) countries.

[Akshay Kapoor]

5. Where will the difference due that be pronounced in the performance between the planes (hint: in the boundaries of the flight envelope, which is where the dalals like Kohkhar and others would have been instructed to focus on.

Moderators I would like to report this post. Its disgusting and its shameful that BR allows this. Makes me ashamed to be part of the BR community.

The person this poster is calling a dalal was one of the finest pilots the country ever had with a stellar record in the 71 war. Read the articles on him posted by TSarkar and Shiv. He was the Chief Test Pilot of Tejas for years and the Head of NTFC. One of the strongest supporters of Tejas who is on record saying its better than the Bison and M2K in key aspects and should be inducted as MK 1 asap. And was recently murdered in Bangalore.

How can you sleep at night after something like this and Moderators, how do you allow this ?

[ritesh]

Simply because when we have any product in your hand , it is evaluated based on 2 criterion. 1) against what it was designed to and 2) How does it perform against its counterparts. That will give us ideas about the improvement of any product. The argument that our adversary do not have it is meaningless. M2k is almost similar aircraft in terms of dimension and engine power. So compression is very much relevant. At least our new aircraft must match a decades old aircraft in performance.

Bad logic that is a recipe for a never-ending wild goose chase (IAF is cleverly using this logic to reject or delay India-made products). It is commonsensical and much better to benchmark a weapon system against what it will be realistically fielded against if a war breaks out. If it is better than that, deploy it -- don't just keep comparing it to weapon systems from much more advanced (but irrelevant for us) countries.

Regards to highlighted part, M2k is Medium category AC and was considered for MMRCA, while Tejas was not.
Why the heck we need to compare at all?
Tejas or any other AC will not either win or lose a war by themselves.

[member_28932]

Looking to the F 16 XL like wing design, It must have a great fuel efficiency because of great gliding ability.

There we go. More English. Now.. "Looking" instead of "Feeling" . Why this is the first time that I think I will ever hear anyone say that that a low aspect ratio fighter wing has great "fuel efficiency" because it has "great gliding ability" . That is something like saying that Tun Tun Mausi will have great mobility because she "looks" rotund!

Anyone who knows anything about these things that the most efficient wings for "gliding" (ie great fuel efficiency ) is a very high aspect ratio wing like that are found in well "gliders".

Guys.. (Victor babu, Vipul babu et al, ), atleast do some basic reading /google up if you need to before posting on this thread. It gets filled up very quickly with "feeling", "looking" and similar stuff and zero thinking and analyzing and reality per laws of physics, or worse, it gets kicked down one level down to "XXXX said this", " Some committee needs to be formed do something with LCA" . Let us keep this focused on facts, engineering and reality and let us keep "looking", "feeling" and make believe firmly in the realm of dance, drama, arts, social studies and political "science" .

For instance, if I were to say that the LCA wing will have really poor gliding characteristics (which is true) it will set off a huge amount of ill informed R&D (Rhona & Dhona) and also shlong is long measuring contests of which aircrafts wing has a better "gliding" characteristics. Such is life.

Sir,

I have already done my home work and I have already googled that before posting. let me quote a paragraph from WIKI regarding the large wings of F16 XL:

"It was built around a 40-inch fuselage stretch. Both the large wing and fuselage stretch yielded a dramatic increase in range at all speeds. In 1979, with a strong positive response by the USAF, GD released the Model 400 for a company funded preliminary design effort."

http://en.wikipedia.org/wiki/General_Dynamics_F-16XL

Large wings are used to boost gliding capability means higher range in same fuel. All uav and reconesis planes uses large wing to fly for a long time from same quantity of fuel.

What I did was to draw up similarity from large wings of F 16 XL with Tejas based on assumption that what is right for F 16 XL is right for Tejas as well.

[Viv S]

Large wings are used to boost gliding capability means higher range in same fuel. All uav and reconesis planes uses large wing to fly for a long time from same quantity of fuel.

What I did was to draw up similarity from large wings of F 16 XL with Tejas based on assumption that what is right for F 16 XL is right for Tejas as well.

Quick googling will help you only so much. To put it simply, a large wing enables a large fuel load. Glide ratio on the other hand is a function of the aspect ratio (and drag coefficient).



Could take off in under 100m with a full 8 ton fuel load and fly 10,000 km.

[brar_w]

^^ And scare the $hit out of pilots when landing

@ VipulDave, Go through this

http://speedy.sh/cNfcT/F16XL-20Public-20Domain-202.pdf

And if you wish to further draw comparisons between the XL and the LCA, I suggest that you move that aspect to the international aerospace thread. As mentioned larger wing also means more room for fuel.

[member_28932]

Indranil and Vipul Dave.

Disagree about Dave posts have enough holes in them to sink a ship -the weight stuff in particular.

Kindly prove me wrong. I have said something which Mr. Tamil Mani has said. I will appropriate any argument proving me wrong.

[member_28932]

^^ And scare the $hit out of pilots when landing

@ VipulDave, Go through this

http://speedy.sh/cNfcT/F16XL-20Public-20Domain-202.pdf

And if you wish to further draw comparisons between the XL and the LCA, I suggest that you move that aspect to the international aerospace thread.

No I do not want to argue further. It was quoted to prove my point.

[member_20317]

Vipul Dave ji welcome to the wonderland. These guys are just ragging a new guy in the school. But they are right. Aspect ratio affects glide performance not the wing area (or wing loading). Better wing loading (increased area) is essentially to give better climb rate.

From your own wiki link for F-16XL:

The enlargements increased fuel capacity by 82%. The F-16XL could carry twice the ordnance of the F-16 and deliver it 40% farther.

Thus fuel had to be increased almost twice as much for half as much range increase. OTOH the MTOW (warload+extra fuel) bounced like a crazy ball.

Since we are discussing LCA (which seems like having a lower aspect ratio then even F-16XL) that would mean full efficiency in flying with MTOW at Leh and advanced landing grounds. If you recall almost all MMRCAs had difficulty in Leh (they never revealed why, but that only means they have something to hide otherwise you would have seen the marketing machines and the chamchas all over the net by now).

We will need the LCA over the highest of high Himalayas, besides other places. And this wing will be a killer app there. We simply cannot afford to place MKIs and MMRCA in the advanced strips considering how costly and difficult to replace they are. And just the way a much hated Marut gave a good account of itself where it mattered you can rest assured even LCA would perform the best where it matters.

Hope you stay around.

[member_20317]

Here notice the differences and see which one is shaped more like a glider:

Concorde
Wingspan: 84 ft 0 in (25.6 m)
Wing area: 3,856 ft^2 (358.25 m^2)
Empty weight: 173,500 lb (78,700 kg)
Aspect Ratio - 25.6^2/358.25 = 1.829337055
Maximum fuel load: 210,940 lb (95,680 kg)
Range: 3,900 nmi (4,488.04 mi, 7,222.8 km)


Boeing 767-200ER
Wingspan : 156 ft 1 in (47.6 m)
Wing area : 3,050 ft^2 (283.3 m^2)
Operating empty weight : 181,610 lb (82,380 kg)
Aspect Ratio - 47.6^2/283.3 = 7.997740911
Maximum fuel capacity : 24,140 US gal (91,400 L)
Maximum range at MTOW : 6,385 nmi (7,348 mi; 11,825 km)

[chackojoseph]

Prasad,

You are right on your point. FOC is achieved while in services. It is not necessary to wait for FOC to complete. In Europe they call it Trance. IAF is doing a mistake like it did for MKI. Unless LCA is flown for multiple hours in realtime conditions, we will not understand the issues. We will end up in figuring problem like we are experiencing in MKI.

Chacko,

No, not trance. Much as I would like to see the mystic european dances -- not in a trance, I would not. Lets call it tranche and dig our way below pakistan all the way to eyeran.

Nice. yes. it is a typo.

[maitya]

Also, why dont you do a wrietup on the aerodynamics of the LCA? Where you are unsure mark it as such. At least it would serve as huge FAQ versus teh "feelings type" rubbish discussions we tend to engage in on a cyclical basis, having the same claims and same rebuttals.
Rest of us can add on other aspects etc.

I will certainly take you and a few others up on that. It has been on my bucket list for far too long. But it has to wait till something due this May.

I'm afraid it seems the discussion over the last couple of pages seems to again be veering towrads "feeling" etc ... so I thought I will, with great trepidition of course since not being from the Aero-side of technology, will post a long-pending and half-finished post on a lay-man's take on "turn rates".
But first the disclaimers ...
Disclaimer 1: Aero gurus (like indranilroy, Shalavji, Vinaji, grand-mullah-enquoobuddin (pissBUH), Ramanji et all) nothing to see here, pls ignore this - except for correcting any glaring mistake which is almost ineveitable.
Disclaimer 2: I'll try add various charts and references in a day or two - if the forum software allows me to edit my own post after a certain number of days (most probably it won't though).

Anyway, here goes:
(do note a far superior and shorter post from Shalavji on this very aspect is available a few pages back - do read it pls).

==================================================================

At the outset, apologies for a long ramble, but from a lay-man pov, Turn Rates are directly proportional to,
1) Load Factor,
2) Lift Co-eff
3) Air Density
4) but are inversely proportional to Wing Loading

i.e. a High Turn Rate requires Low Wing Loading, high Lift Co-eff and high Load Factor (and higher air density or lower altitude, but this can be taken to be a constant while comparing two diff aircrafts flying at similar altitude etc.)

So let’s examine each of them one by one from LCA perspective:

1) First the Load Factor: Well Load Factor = L/W (L=Lift, W=Weight) - for a all-metal heavy wing (like that of most contemporary fighters) will have a lower load factor compared to lighter all-composite wing like that of a LCA. So heavier wing -> Lower Load Factor, for the same amount of lift -> impacting the turn-rate negatively.

Another way of looking at the load factor is to co-relate with the bank-angle of the turn - simply put cosine of the bank angle = 1/Load Factor. So, for a 60 degree banked turn a load factor of 2 (as Cos 60deg = 0.5), often called a “2 g” turn, is required while the load factor required for 45deg turn is 1.414. Conversely, if the platform is able to withstand a 9G turn, the bank angle achieved (theoretically) would be approx 84deg.

So, if you already have a heavy metallic wing, and add more weight to it by suspending ordances/fuel-tanks etc, your load factor will go down, allowing you to turn more slowly (lower bank angle). However with a lighter composite wing (with same external weight attached and exact same wing geometry allowing exact same Lift as in the metallic wing case), you reduction in load-factor would be lesser, allowing you to turn quicker (higher bank angle).

The LCA Wing material tech (CFC) wins here, as opposed to myriad of other platforms with metallic wing constructs.


2) Second is the Wind Loading: Wing Loading is nothing but weight of the wing divided by the wing area. Any delta wing (thus LCA as well) will traditionally have larger area thus wing loading will be lower - however a CFC based light wing as in LCA, provides further advantages towards lowering the wing loading.

Refer to a few pages back to ravi_g's post -
Clean-Wing loading:
LCA -------- J-10 ------- F-18 ------- F-16C
247kg/m² --- 381kg/m² --- 459kg/m² --- 431kg/m²

Thus low-wing-loading design like that in LCA, helps in higher turn-rate compared to even-other delta designs, again because of extensive use of composites.


3) Third is Lift co-eff: Now this is a bit difficult to explain and frankly, it needs to be examined along with the drag co-eff as well. One way is to look at the L-D diagrams where you have 2-D representation of the Lift Co-eff on main axis and the Drag Co-eff on the secondary axis against the angle-of-attack (other is to simply plot the ratio of lift:drag against the AoA or even plot all three together against AoA).

Simply put for a normal rectangular wing plan-form, Lift Co-eff (and of course the Drag Co-eff as well) will increase, quite steeply, with increase in AoA - but upto a point (called Critical AoA), after which with any further increase in AoA the lift co-eff will start reducing (and suddenly, almost at that point, the drag co-eff would start increasing almost exponentially) - net effect the wing will stall.


3a) Diff Load Factors:Before we go further, let's consider another variable, the turn velocity, and two more limits viz. the Structural Load Factor and the Aerodynamic Load Factor ...

Again, simply put, the Aerodynamic Load Factor would limit the turn-rate (due to stall, so governed by Max Lift Coeff) irrespective of amount of structural load (aka Gs) you can still pull. This velocity is called the corner velocity and flight condition where this occurs is the corner point.
So irrespective of how strong the paltform is structurally, the max turn-rate you can achieve is limited (Aerodynamic Load Factor) by the Lift Co-eff which in turn is function of the planform geometry of the wing.


3b) Instantaneous and Sustained Turn Rates: The turn-rate you achieve at corner velocity is the Max Instantenous turn rate (and minm turn radius).
Now let's look at how Lift Coeff comes into play for different wing geometries.

For a rectangular wing planform, the lift co-eff has been explained above - wherein the lift co-eff increases steeply and monotonically with increasing AoA, until a point it stops and starts reducing. But, with a delta plan-form this dipping of Lift Co-eff beyond a certain AoA, doesn't happen at all ... aka, THEORETICALLY, the lift co-eff can continue to increase with increasing AoA.
Thus, again THEORETICALLY, the turn-rate will be higher than that of the normal wing planform design - and so, traditionally the Deltas will have higher Instantaneous turn rate than that of rectangular planform design.

But of course, there's a huge catch - pls wait a minute, and pause for the drag-bhaiya to play it's part as well. The drag co-eff, however will also continue to increase and eventually negate all lift.

So your turn-rates (and thus the Instantaneous turn rates) will be impacted as you would rapidly bleed energy (due to drag) and your turn velocity will start reducing quite dramatically. The only way to negate this drag is to use addn thrust and overcome it and thus maintain/sustain this turning velocity. This is called the sustaining turn rate which obviously is lesser than the pure lift-coeff-influenced-instantaneous turn rate.

Moreover, for a delta wing, because of relatively higher wing area, will have more drag compared to that of a normal wing design i.e. for a delta planform, because of a higher wing area (compared to that of a normal wing geometry) BOTH lift and drag would be higher than that of a normal wing design.

So for a delta planform, the limiting factor for higher turn-rates, is not the lift co-eff so much, but it's the amount of thrust available to overcome this drag that turns out to be the limiting factor - which would mean a higher Instantaneous turn rate (due to higher Lift Co-eff) but a lower Sustained turn rate (due to again higher Drag co-eff) for the deltas, when compared to a rectangular wing design.

But, unfortunately, that's not the end of the story.


3c) The Vortex influence on Lift: Now plane designers are constantly looking at ways and means of increasing lift co-eff while postponing, as much as possible, the corresponding and inevitable drag increase. An "artificial way" of getting this done is to have the flow on the upper surface of a wing rejuvenated/energised by vortex generated upstream.
The energised airflow on the top-surface of the wing provided greater "suction", increasing the lift, without corresponding exponential increase in drag.
This is called postpoing the wing-stall.

Now leading edges of a delta are good vortex generators - for any delta wing, all along the leading edge, vortex are generated (until they are unaffected by a phenomena called vortex breakdown) and thus contribute to vortex lift which increases with increase in AoA.


3d) Vortex Burst Limitations: But then again, as with everything else, there's a catch ... vortex getting generated tend to "burst" or destroyed (due to adverse pressure gradients acting on them) resulting in a loss of most of the vortex lift - pls do note vortex bursting is not an issue as long as it can be postponed to a far-enough point downstream to a wing.

And there-in lies the problem ... for a slender delta-wing (aka with high-wing-sweep of say 65deg, found in most modern delta-winged aircraft like Mirage etc) this vortex busting phenomenon is observed to start from around 18deg AoA for a 0.85M flight regime. Increasing the AoA beyond that, the vortex bursting point moves upstream very quickly resulting in abrupt reduction of Lift etc - and about 24deg the wing starts to stall.


3e) The Canard Solution: The TFTA solution to counteract this phenomenon is of course to introduce the close-coupled canard surfaces located just above and forward of the main wing that'll direct airflow downward over the wing. At slow-speed and high AoA it generates vortex which attaches to the upper surface of the wing, stabilising and re-energising the airflow over the wing reducing drag and increasing lift.


3f) Non-Slender Delta planform Impact: But SDREs, being insufferable fools that they are, thought of something else ... how about a non-slender delta (aka with relatively low-wing-sweep of say ~50deg) wing. And like bumbling fools, they soon found out that vortex bursting would onset at a even smaller AoA for a non-slender wing.
But like a true SDRE, they kept their patience to soon found out a phenomenon called flow-reattachment which re-energises the airflow over the wing reducing drag and increasing lift.

Plus as a bonus, they also found out that vortex breakdown is not a limiting phenomenon as far as the lift force is concerned for nonslender wings - on the contrary, flow reattachment is the key lift-enhancing contributor.


3g)The SDRE LCA Wing Planform: So, they decided to have best of both the worlds ... have a wing which will have both non-slender and slender delta planform. And viola, you got the compound delta LCA wing design, with it's both a low-wing-sweep (50deg, so non-slender delta) and high-wing-sweep (~63deg aka in the "slender delta" territory) as you move from inboard (wing root) to outboard of a wing.

Thus for the relatively lower part of the high-AoA flight regime (say from around 18deg to 22deg etc), the outboard slender delta part of the wing would dutifully contribute to the vortex lift while keeping the drag as low as possible. And with further increase of AoA, as that part of the wing starts to stall due to vortex bursting etc, the inboard non-slender-delta part of the wing will come into play with it's flow-reattachment aspects and keep on further enhancing the lift co-efficient (while still keeping the drag down as low as possible).

So where is the need of any additional control surface like a canard (and thus without the weight and complexity penalty of an additional control surface etc), hain jee?

Ofcourse, nothing is infinite, and there'll still be a stall angle when the non-slender part of the wing will also give up on flow-reattachment etc, and the whole wing will stall - but then FBW fly-control system will not allow that situation to arise anyway.

[Cain Marko]

Disagree about Dave posts have enough holes in them to sink a ship -the weight stuff in particular.

Kindly prove me wrong. I have said something which Mr. Tamil Mani has said. I will appropriate any argument proving me wrong.

Well, not trying to prove anything since I am no aero guru but was not sure about AESAs being lighter than mechanical arrays. Thought ESA antennas are a lot heavier and require more cooling, which would probly add weight. Also not sure about 300kg ballast; this is used to mimic the weight of the mk2 (indicating the possibility that the latter will be heavier, not lighter) based on an article by B Karnad

[SaiK]

maitya, great post!

could you also muse (perspective analysis) about design changes needed for expanding LCA platform for
~ mach 2
~ super cruise
~ may or may not have internal weapons

now, this is not about AMCA at all.. just extender. You may not consider to respond in this thread.

tia

[Shreeman]

What is it with this strange affliction towards TFTA characteristics. Lets do some homework. Ask googul the jamnagar to chahbahar distance. then ask chaacha to give you mach 2 in miles or kmph.

Now unless you want to fight eyeran sitting in jalandhar, this whole brochritis has no real purpose. In reality the Mach 1.x intercepter will do its joib without costing an arm and a leg. Like Windows XP.

For the rest, instead of the malkhamb practice that is +9g or 39deg AoA, stick some reasonable sensors and a helmet mounted sight. If this doesnt solve your problem then things are already past a skirmish and in a war you are not doing mach 2 point A to B for interception. Radars will be on and air defenses will be senbding up lead faster than your mach 2 bullet.

All this hitting the other side of earth in half hour is TFTA. It has no business in a "we are not fighting a war, farther than 1000 km from our borders" paradigm.

An intercepter that wants to protect (read ask nicely to go away) 500km radius doesnt need bells and whistles.

I should really not be throwing up these wild ideas but such is the ignorant self.

[Prasad]

Shreeman ji,
The IAF may not want ask that jazz butt would the navy want it since it will operate without the land based ecosystem.

[member_28652]

Maitya really great post. Truly illuminating.

[Shreeman]

Shreeman ji,
The IAF may not want ask that jazz butt would the navy want it since it will operate without the land based ecosystem.

Prasad sahib,

Follow the logic a bit further.

Land based adversaries can bring numbers. Sea based? Not so much.
Speed costs fuel, to go and come back. How far out will the CBG want to stay in the clear? 500 miles -- roughly an hour to target. Or even farther out? Who will you be running from at sea? Would you want endurance and mutirole capability or pure Mig25 speed? Then there are the unsinkable carriers. Goa? Vishakhapatnam? Kochi? Andaman? You are not squatting for years off eyeraan, you know.

In the naval scheme of things, M2 is far less important than higher fuel fraction and mutirole capability. You need to stay up. The harrier was neither very agile nor all that fast. And it fills a great role at sea for IN and even the US marines.

This mach 2 fascination has no context attached to it. Running to or away fast has no real role for a 500km intercepter with BVR slung underneath. They can do Mach Xs as needed. As long as you can run Mach 1.x, stay on station for a reasonable time (unlike the 21s), you will wave off anyone who comes near just fine.

Now if you want a 3.5t load craft to also carry a 1.5t land attack weapon or go mach 2, then you have
fantasy issues. What circumstances might arise where this warload is actually going to be needed?

Domestic weapons are made to fit strategy, the other way around is jugaad. The LCA can police the CBG, the 29ks will carry the heavy load, because they have two tail pipes designed for that role.

[Prasad]

Agreed on all points. I suppose the only question wrt the naval version is how long can it stay on a patrol type station with a bvr+wvr loadout with or without a single centreline droptank. And given their longterm plan, theyll be ok with making it work even if it falls slightly short of their expectations.

[Shreeman]

Agreed on all points. I suppose the only question wrt the naval version is how long can it stay on a patrol type station with a bvr+wvr loadout with or without a single centreline droptank. And given their longterm plan, theyll be ok with making it work even if it falls slightly short of their expectations.

Presume the requirements were laid out with IAC/vik in mind. No one seems to be complaining of short legs on the naval front. Just the heavy tail hook as far as i have read in the neuj media.

[Akshay Kapoor]

Maitya,

thank you for taking the effort to post this. This is what BR should incubate...knowledge building and thoughtful analysis. But I digress. Couple of quick questions.

1, 2 (especially 2)- Delta wing vs metal wing LF and WL. What is the difference in quantum of turn achieved (degrees of ITR and STR) because of composite vs metal in LCA's case. I know that's a hard question as there are several variables but an educated guess would be very welcome.

3 b - Correct, the limiting factor is the thrust weight not wing design. So with LCA MK1 engine what STR do you think we can reach realistically. What would be doable say with total weight of 9.5/10 tonnes (half fuel plus missiles) ?

3 g - Silly question I'm sure - the regime shift from slender to non slender is seamless in terms of AoA increase. So as the pilots maneuver and increase AoAs from 18 to 26 is there a section of AoA flow detaches at X say 20 for slender but the regime shift from slender to non slender has already happened at Y say 18 so flow has come back and there is no problem ? Obviously its all been tested till 26 AoA so it is fine but I just wanted to understand this in the regime shift terms.

Finally what STR and ITR do you think we have on MK1 ? What will it be on MK 2 after nose plug etc ?

[member_28730]

Maitya, superb post, truly educative ... thank you

[saumitra_j]

Maitya sir, as usual a great post. Thank you very much. I hope this puts an end to any thoughts around the need for a canard for the Tejas....if somebody still thinks so, please read this section and understand it!

[Lalmohan]

maitya-ji, one comment and i may be wrong, isn't it about total weight and not just wing-weight?