ADA Tejas (LCA) News and Discussions

[akshay m]

Induction of Tejas Fighter Plane in IAF

Subsequent to the Initial Operational Clearance (IOC) of Light Combat Aircraft (Tejas), Hindustan Aeronautics Limited (HAL) has handed over the First Series Production (SP1) of Light Combat Aircraft (LCA) to the Indian Air Force (IAF) on 17.1.2015.

The requirement of fighter aircraft is periodically reviewed and it is ensured that the operational requirements of the IAF are met. The IAF is in the process of inducting additional Su-30 MKI aircraft apart from Light Combat Aircraft (LCA). An Inter-Governmental Agreement has been signed with Russian Federation for design, development, production etc. of a Prospective Multi Role Fighter Aircraft. The procurement of Medium Multi role Combat Aircraft (MMRCA) is also under process.

This information was given by Defence Minister Shri Manohar Parrikar in a written reply to Shri Rajkumar Dhoot in Rajya Sabha today.
http://http://www.business-standard.com/article/government-press-release/induction-of-tejas-fighter-plane-in-iaf-115031700604_1.html

 

[smestarz]

Haha thats laughable ask any body no one will appreciate intervention of govt in defense. The thing need to be done is kill the kickbacks

In every deal the govt is involved, after all who pays? The services? The services only suggest what weapons they need, they do not buy them. Till last year, the services will just point to a weapon and the govt would be eager to buy it and that made the services a BRAT AND A BULLY. And they went left right and centre pointing to everything they could and in 1990s we were almost bankrupt.
Though services like something, to buy or not is Govt decision, why else you explain the Rafale deal is not signed? The IAF chief has been crying with comments like "THERE IS NO PLAN B" So there is still intervention of the Govt. If there was no intervention of the govt then the follow on contract for service of Pilatus for 5 years would have been signed and we would have ordered the entire fleet of piston engined trainers from Pilatus.

I am anti Rafale and pro Tejas Camp. Even called Tejas Fan boy so I agree with you.What was your point here????

The point here is that the requirement is for planes that are replacement of single engine MiG-21 and as many people have pointed out, that is Tejas. It is more capable even than Mirage 2000 and cheaper to produce and maintain. Going by the price of US$ 22 billion as informed by RM in parliament that comes to US$ 175 million per Rafale as per the contract, and considering the price of Tejas is US$ 35 million per plane, we can buy 5 Tejas or 4 Tejas and spares. Thus if we say 4 Tejas and spares we can get 504 Tejas and Spares for them. Wasnt the IAF talking about numbers? Tejas will give them
Even if IAF orders 200 Tejas the cost will be US$ 7 billion, the cost of produced Tejas will be less than half of off the shelf Rafale.
What India needs is single engine plane to ensure that it has good flying ratio to ensure that the cost of operations are lower and can be sustained.
Just because A-380 is big plane and carried big load, all the air lines do not order A-380 right?

Situation of IAF is like they went to buy a toothpaste, but somehow Dassault convinced them that they have a problem with body odour and they should buy Liquid soap. Now, IAF wants to wash teeth with this soap also.

Yes GOI only decides and allocate funds they do not choose the weaponary they have to rely on these so called defense experts to buy anything.
It is Army ,IAF,Navy who have the right to choose there gadgets and not MOD. MOD doesnot decided anything in regard to it apart from the funds. Prioritization of what to buy is not done by MOD.

True, but that is thing of past, its first time we went for RFP also, did we not? IT is true that the forces tell the GoI what they want and most of the earlier RMs were people who were into kickbacks rather than anything else, right now we have a RM who is well educated and well read and of course, he has Defence people as his ADC should he want to know more. The Forces tell the GoI what they want, but its upto to govt to sign or refuse. Thus "Services proposes, GoI disposes" RM since he has ADCs who do give him some insight about various things, are good source of information. The question MoD asks is ".. earlier you said that Su-30 MKI is the best plane and Rafale was in production when India purchased Su-30 MKI, so what changed? " Performance wise Su-30 MKI gives Rafale run for the money, only one question is avionics and I am sure RM does tell the IAF that new technologies and avionics developed for 5th Gen PAKFA will soon find way into Su-30 MKI. India might not be doing well in production of engines, but we are doing well in situation of avionics. One of the arguements the IAF top brass can still talk is that Rafale is Medium MRCA it sounds as if its either RFP for Navy or that IAF plans to send planes to the next olympics boxing or weight lifting.

Again I cannot say anything apart from laughing....MoD And Defense are linked,dependent and not controlled by each other so we need both on the same page...
And its just not for Tejas but for Arjun and many other projects. Every person who retired has said in favour of domestic arms but while they are on chair they behave anti Domestic products

Kindly read the context of what I wrote before replying i think u missed my point

Services are supposed to be part of MoD, but when the decisions are being thought, and RM is on record about it even during Aero India, and the service chief still shouts off his mouth saying "there is no plan B" that shows that the service chief is undermining the MoD. The service chief takes the orders from MoD, but the IAF chief had become so arrogant that they feel that if they say that the govt would cower and just sign the deal. It was matter of just who blinks first and it was the IAF chief.
Now that IAF is on the same page as MoD, things can go in better way.

There is no way that GoI will sign the Rafale deal at US$ 22 billion. unless France comes with heavy discount.

Further let me remind you something, IAF had downselected Rafale and Eurofighter thus IAF trials found both are equally capable. Rafale won L1 because it was found to be cheaper overall (cost + LCC)
Since the price what Dassault asks is high, and GoI cannot agree to that, its easy to just cancel the RFP. With the pressure of signing gone, and other players becoming "available" there is good chance that India can find a much better deal. Even Dassault could offer a better deal since they know now that India means business and they wont be pushed to sign. It is buyers market and we decide what to buy.

But still i prefer to just cancel the RFP and go for Tejas in numbers and maybe license SPECTRA if required.

 

[Kunal Biswas]

 

[Kunal Biswas]

Budget allocation for Air-force, Source Broadsword ..

 

[Khagesh]

Didn't quite read the whole post above but this particular line was hilarious:

Situation of IAF is like they went to buy a toothpaste, but somehow Dassault convinced them that they have a problem with body odour and they should buy Liquid soap. Now, IAF wants to wash teeth with this soap also.

One smart alecky line.

 

[ersakthivel]

Some advantages of low wing loading fighters ,


Some thing else to clear the collective cobwebs in the brain of of all guys who lack info for a decent debate.

Banked turn - Wikipedia, the free encyclopedia

When a fixed-wing aircraft is making a turn (changing its direction) the aircraft must roll to a banked position so that its wings are angled towards the desired direction of the turn. When the turn has been completed the aircraft must roll back to the wings-level position in order to resume straight flight.[4]

When any moving vehicle is making a turn, it is necessary for the forces acting on the vehicle to add up to a net inward force, to causecentripetal acceleration. In the case of an aircraft making a turn, the force causing centripetal acceleration is the horizontal component of the lift acting on the aircraft.

What this effectively means is the acceleration of any fighter in a sustained turn depends upon the "horizontal component of lift acting on the fighter".

In straight, level flight, the lift acting on the aircraft acts vertically upwards to counteract the weight of the aircraft which acts downwards. During a balanced turn where the angle of bank is θ the lift acts at an angle θ away from the vertical.

It is useful to resolve the lift into a vertical component and a horizontal component. If the aircraft is to continue in level flight (i.e. at constant altitude), the vertical component must continue to equal the weight of the aircraft and so the pilot must pull back on the stick a little more. The total (now angled) lift is greater than the weight of the aircraft so the vertical component can equal the weight. The horizontal component is unbalanced, and is thus the net force causing the aircraft to accelerate inward and execute the turn.

Because centripetal acceleration (a)is:

a=v*2/R

Newton's second law in the horizontal direction can be expressed mathematically as (θ is the bank angle)

L sin(θ)=mv*2/R

This formula clearly shows that fighters with higher lift(lower wing loading ) can achieve a quicker sustained turn with lesser bank angles.

Also it clearly shows that for the same speed fighters with higher lift (low wing loading) can have a smaller radius of turn.

What is the significance of the above two point in a turning fight?
where:

L is the lift acting on the aircraft
θ is the angle of bank of the aircraft
m is the mass of the aircraft
v is the true airspeed of the aircraft
r is the radius of the turn
In straight level flight, lift is equal to the aircraft weight. In turning flight the lift exceeds the aircraft weight, and is equal to the weight of the aircraft (mg) divided by the cosine of the angle of bank:

L= mg/cos(θ)

where g is the gravitational field strength.

The radius of the turn can now be calculated

r=v*2/g tan(θ)

This formula shows that the radius of turn is proportional to the square of the aircraft's true airspeed. With a higher airspeed the radius of turn is larger, and with a lower airspeed the radius is smaller.


This formula also shows that the radius of turn decreases with the angle of bank. With a higher angle of bank the radius of turn is smaller, and with a lower angle of bank the radius is greater.



SO now it is clear while lift has nothing to do with radius of turn, it is the sole thing that determines the all important " net force causing the aircraft to accelerate inward and execute the turn".

SO if you have lesser lift your horizontal component of the lift force which determines your acceleration will be lower. It means the pursuing fighter with higher wing lift(low wing loading fighter) will shoot you down with his guns , because his acceleration is faster.



Wing loading - Wikipedia, the free encyclopedia

Effect on turning performance

To turn, an aircraft must roll in the direction of the turn, increasing the aircraft's bank angle.

Turning flight lowers the wing's lift component against gravity and hence causes a descent. To compensate, the lift force must be increased by increasing the angle of attack by use of up elevator deflection which increases drag.

Turning can be described as 'climbing around a circle' (wing lift is diverted to turning the aircraft) so the increase in wing angle of attack creates even more drag. The tighter the turn radius attempted, the more drag induced, this requires that power (thrust) be added to overcome the drag.

The maximum rate of turn possible for a given aircraft design is limited by its wing size and available engine power: the maximum turn the aircraft can achieve and hold is its sustained turn performance.

As the bank angle increases so does the g-force applied to the aircraft, this having the effect of increasing the wing loading and also the stalling speed. This effect is also experienced during level pitching maneuvers.



So it is crystal clear now that high wing loading fighters have to have more AOA (to stop the descent) in a Sustained turn. This can be achieved only by using the up elevator which increases drag. This increased drag will lead to lower acceleration.

But fighters with low wing loading don't have to increase the AOA by that much, (to get a higher lift component to stop the descent). So they dont have to use up elevator that much, which results in lower drag and increased acceleration in turns.


Aircraft with low wing loadings tend to have superior sustained turn performance because they can generate more lift for a given quantity of engine thrust. The immediate bank angle an aircraft can achieve before drag seriously bleeds off airspeed is known as its instantaneous turn performance. An aircraft with a small, highly loaded wing may have superior instantaneous turn performance, but poor sustained turn performance: it reacts quickly to control input, but its ability to sustain a tight turn is limited. A classic example is the F-104 Starfighter, which has a very small wing and high wing loading. At the opposite end of the spectrum was the gigantic Convair B-36. Its large wings resulted in a low wing loading, and there are disputed claims[who?] that this made the bomber more agile than contemporary jet fighters (the slightly later Hawker Hunter had a similar wing loading of 250 kg/m2) at high altitude. Whatever the truth in that, the delta winged Avro Vulcan bomber, with a wing loading of 260 kg/m2 could certainly be rolled at low altitudes.[10]

Like any body in circular motion, an aircraft that is fast and strong enough to maintain level flight at speed v in a circle of radius R accelerates towards the centre at . That acceleration is caused by the inward horizontal component of the lift, , where is the banking angle. Then from Newton's second law,

Mv*2/R=L sin(θ)=1/2(v*2 * p* Cl* A* Sin(θ))

Solving this we get turn radius R

 

[ersakthivel]

From the link

Myth Bustng - The advantages of low Wing Loading | Forums - Page 4

The lower the wingloading, the lower the angle of attack you have to pull to carry out the same manoeuvre (other things being equal)

If you look at the lift and drag equations, you can see why that's so important.

Lift (N) = CL * area (sq m) * .5 * pressure (kg/cubic m) * velocity (m/s) squared

Coefficient induced drag (CDi) = (CL^2) / (pi * aspect ratio * Oswald efficiency)

Drag = coefficient * area * density *.5 * velocity squared

If you look at the equations, induced drag increases with the square of CL, and proportionately with the increase in wing area. So double wing area = a quarter the CL = half the induced drag.

To plug some figures in, an example aircraft with weight 3000 kg and wing area of 10 m^2, then the same aircraft with 20 m^2 wings. (this assumes weight doesn't increase with the larger wings, of course)

Assuming lift = 4 times weight, sea level density, speed = 400 km/h

117,600 = CL * 10 * .5 * 1.225 * 111^2
CL = 1.56

CDi = (1.56^)/(pi*6*.8) = 0.16

Induced drag = 0.16 * 10 * 1.225 * .5 * 111^2

Induced drag = 12,074 N

Now the same thing but with double the wing area

117,600 = CL * 20 * .5 * 1.225 * 111^2
CL = 0.78

CDi = (0.78^)/(pi*6*.8) = 0.04 (note how doubling the wing area results in a quarter of the CDi, because CL is squared)

Induced drag = 0.04 * 20 * 1.225 * .5 * 111^2

Induced drag = 6,037 N

Of course, parasitic drag increases with a larger wing area, but basically lower wingloading = an increasing advantage the tighter the turn, and the lower the IAS you fly (and IAS of course is lower at high altitudes)

these equations need no explanation as you your self has said that you are very talented in maths and physics.

Even though the weight increase due to larger wing is not factored in this formulae, the general directions of calculations are valid forever.


So, lower wing loading gives,

Lower stall speed, tighter turns (in general).

Usually wings will stall at the same angle of attack, however planes with low wingloading will reach this angle of attack at a lower speed.

huge wing and a low weight aircraft you will get a very very low stall speed,

for example and probably a pretty good turner.

Another quote below,

In general, aircraft with higher wing loadings tend to be faster but less manoeuvrable. Since speed is life, this has historically been a good betting proposition. However, once top speeds become supersonic the trend can break down due to the operational, aerodynamic and thermodynamic issues associated with supersonic flight. As a result of this, current fighters are no faster than 1960s fighters, but generally have lower wing loadings, since if you can't go faster the next best thing is to turn harder (apart from which, low wing loadings are necessary for high supersonic L/D and therefore help towards supercruise). As such, wingloadings are likely to stay roughly constant or possibly even decrease in future designs until such time as the upward trend in speed reasserts itself.

An aircraft's lift capabilities can be measured from the following formula:
L = (1/2) d v2 s CL

* L = Lift, which must equal the airplane's weight in pounds
* d = density of the air. This will change due to altitude. These values can be found in a I.C.A.O. Standard Atmosphere Table.
* v = velocity of an aircraft expressed in feet per second
* s = the wing area of an aircraft in square feet
* CL = Coefficient of lift , which is determined by the type of airfoil and angle of attack.

The lower your wingloading, the less AOA you have to pull to get the same lift vector.
It is you lift vector that turns the plane as well as allows it to climb and fly.

For turning I would rather have a wing that needs less AOA than one that allows me to use more
but really needs it. The latter will have worse drag.

some counter arguments like the one beolw,

Basically wingloading usually defines the aircraft's stall speed (a least in combat, without lift assisting devices such as slats and flaps), and through it, how slow the aircraft can get in turn, and thus the turning circle.

Simply to put, planes with low wingloading are usually having smaller turning circles.

Low wingloading on the other hand is not so pronounced as far as turn rate, or in other words, turn times go. Turn times are basically defined by how high G the aircraft can hold up in a sustained manner. That is basically speaking a race between the thrust of the propeller vs. the drag of the aircraft in turn. Here low wingloading doesn't give much of an advantage, as - all things equal - you will have a larger area wing, and thus higher drag to achieve lower wingloading. You will need more thrust to overcome the greater drag, if you're pulling the same Gs, or rate of turn.

The effect of increasing thrust (ie. engine output, 'boosting') on turn is interesting. Even huge increases in excess thrust (either by increasing engine power or doing a descending turn - tactics, tactics!) have very small effect on turn radii, since the aircraft just can't go below it's given stall speed at a given G-loading. However, increasing excess thrust can have a VERY pronounced effect on turn times.

Simply to put, low wingloading planes don't neccesarily beat high wingloading planes in turn times.

Best examples are the Yakovlevs vs. Spitfires. Spitfires have very low wingloading, and high thrust, high drag; the Yakovlevs have a fairly high wingloading, low thrust (poor engines), and very low drag. Comparing their real life turn radii and time values reveals the Yakovlevs have larger turn radius (by about 50m - about as much as the 109G, differences in turn radii were not as pronounced as some may think), but at the same time they beat the Spits in turn time by about 2 secs for a 360 degree turn.

It's classic example of how drag, thrust and wingloading effects turn time and radii. Turn time is IMHO more important, not to mention the other benefits of high wingloading being still there - lower drag, effecting level speed, zoom climb, dive performance etc.

but this counter argument doesn't stand the test of equations.

 

[myana]

Great news

https://twitter.com/SJha1618/status/578243230543716353

HAL has been told to increase Tejas output to 16 from next year. But they want more MK-I numbers committed.
There is now some preliminary discussion on an improved MK-I with certain new systems and easier maintainability.
This will keep the HAL line buzzing till 2022 when Mk-2 production is expected to take off.

Means 16 a year full 6 years(assuming mk-2 will arrive beginning 2022) total mk1 flying will be 100+

 

[ersakthivel]

As per Rate of turn and Radius of Turn equations,XXX degree bank at ZZ speed would produce the same turn rate regardless of the aircraft weight or wing loading ..

Rate of turn and Radius of Turn which I reproduce here also.
Rate of turn T (*/sec)= 1091*tan(bank angle)/v
Radius of turn R (ft)=v^2/ 11.26 tan(bank angle).

So it may seem larger wing area(lower wing loading airfame) has no advantage over low wing area ( higher wing loading) plane in any sustained turn or Instantaneous turn because Any aircraft travelling at the SAME SPEED and pulling the SAME G and therefore at the SAME BANK ANGLE, will have the SAME RATE and SAME RADIUS. Doesn't matter if it is a low wing loading or high wing loading fighter!!!!

because the above equation use nothing but bank angle and , v(air speed ) to calculate rate of turn and radius of turn.

wing loading / g force / turn rate - PPRuNe Forums

this link explains it all in clear terms with no sophisticated equations!!!!

Another illustration. A rate one turn which is defined as being 360 degrees in two minutes, requires a higher angle of bank, and therefore higher g, the faster you are going. In a light twin, a rate one turn is generally less than 25 degrees bank, in a faster passenger jet, the rate one turn requires more angle of bank, to the point where passenger jets are limited by 25 degrees bank angle during instrument procedures and light twins are limited by rate one. The only reason for this is that the passenger jet is going faster, if it slowed down to the speed of the light twin, the rate would be the same.

SO higher wing loading plane has to fly closer to its peak AOA and closer to its stall speed (with higher drag due to higher AOA),to do the 360 deg turn in 120 seconds. Because of its lower wing area it has to fly faster to get a higher horizontal component of lift that will let it remain at the same altitude.


An aircraft travelling at the SAME SPEED and pulling the SAME G and therefore at the SAME BANK ANGLE, will have the SAME RATE and SAME RADIUS. Doesn't matter if it is a Tiger Moth or a Foxbat.

But in real world,


My tiger moth, in a 60 degree banked turn will pull 2 gs and whip around through 360 degrees in under a minute. Your Foxbat, travelling at Mach 3 will take a long long time to do 360 degrees in a 2 g turn.

Why?

Lets look at extremes again to see why an aircraft with a low wing loading can out turn an aircraft with a high wing loading. Lets say the low wing loading aircraft is the Tiger Moth and the high wing loading aircraft is an experimental aircraft very similar to the Tiger Moth except it has such stubby wings that at 85 mph it requires an angle of attack close to the stalling angle to generate enough lift to maintain height.

Both aircraft cruising along at 85 mph together and they both enter a gentle 15 degree bank to the right. Both aircraft increase angle of attack slightly to maintain altitude. This brings the experimental aircraft even closer to the stalling AoA but at the moment it's not quite stalling.

Both aircraft are now at the same speed, pulling the same G and getting the same rate and radius of turn.

But what happens when the Tiger Moth increase bank angle even further? The experimental with very high wing loading tries to match it but doesn't have any excess angle of attack to use and stalls. Meanwhile the Tiger happily putts around in a nice tight turn.

So while the Gs and speed were the same, the aircraft had the same turning performance. But the low wing loading on the Tiger Moth meant it had plenty of excess angle of attack to use to further increase bank and therefore rate, radius and G.

Lets look at extremes again to see why an aircraft with a low wing loading can out turn an aircraft with a high wing loading. Lets say the low wing loading aircraft is the Tiger Moth and the high wing loading aircraft is an experimental aircraft very similar to the Tiger Moth except it has such stubby wings that at 85 mph it requires an angle of attack close to the stalling angle to generate enough lift to maintain height.

Both aircraft cruising along at 85 mph together and they both enter a gentle 15 degree bank to the right. Both aircraft increase angle of attack slightly to maintain altitude. This brings the experimental aircraft even closer to the stalling AoA but at the moment it's not quite stalling.

Both aircraft are now at the same speed, pulling the same G and getting the same rate and radius of turn.

But what happens when the Tiger Moth increase bank angle even further? The experimental with very high wing loading tries to match it but doesn't have any excess angle of attack to use and stalls. Meanwhile the Tiger happily putts around in a nice tight turn.

Wing loading and G loading are not the same thing. If both planes fly at the same speed and bank angle (and experience the same G loading as a result of this bank angle), they will have exactly the same radius of turn.
.
I'd say that when comparing two airframes of similar weight but one with twice the wing loading (ie half the wing area), the aircraft with the higher wing loading is most probably designed to fly significantly faster. Therefore, with both at their design speed at any given bank angle and hence G loading, the faster aircraft will have a greater radius of turn. If both do fly at their design speeds, they could well fly at a similar angle of attack and there is no reason why the faster aircraft would 'run out of spare angel of attack' sooner than the other.

Now, if both of them do fly at the same speed (the design speed for the slower aircraft), the aircraft with the higher wing loading will be flying closer to its stalling angle of attack, to compensate for the loss of speed.

If in this situation they both fly a turn at a given bank angle the radius is still the same. However, the faster aircraft will be the first to reach a bank angle (and associated G loading and angle of attack) that will make the wing stall.

So, at slow speeds the aircraft with the lower wing loading could out-turn the one with the higher wing loading. But only because the aircraft with the higher wing loading is flying at a speed it is not designed for (ie too slow) and would be the first to stall.

 

[ersakthivel]

Air Chief Marshal (retd) S. Krishnaswamy says in

The Week | Get those Rafales, quick

Rafale is certainly a much-needed addition to the Indian Air Force. During the Kargil conflict, only Mirage 2000 had the capability to deliver a precision-guided bomb accurately on Tiger Hill, putting to rest the criticisms over its acquisition. We have ensured that its special features are embodied on the light combat aircraft and Su-30MKI.

thats what the test pilot Suneeth krishna and NTSE chief Riaz Khokar were saying earlier.

 

[ersakthivel]

The tejas Wing Planform: So, they decided to have have a wing which will have both non-slender and slender delta planform to get vortex generation in all AOAs.

That is the reason for 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), ?

SO to counter the rapid loss of energy in turns by plain deltas , tejas was designed with two different wing sweeps, wing twist at the root, larger wing area and higher thrust to weight ratio as well.

For the F-16 the horizontal stabilizers come in the wake of the wing at greater than 25 degrees AoA, i.e become ineffective .

This is called a deep-stall (or super-stall) and is mostly unrecoverable. Therefore the F-16 is limited by its FBW to 25 degrees AoA.

SO not having a tail in tejas is the right thing to do, because with shorter fuselage length than F-16 , it would have created more problems in tejas than the longer f-16.

 

[Lions Of Punjab]

 

[Lions Of Punjab]

 

[Lions Of Punjab]

 

[Lions Of Punjab]

 

[Lions Of Punjab]

 

[Lions Of Punjab]

 

[Lions Of Punjab]

 

[Lions Of Punjab]

 

[Lions Of Punjab]