AMCA - Advanced Medium Combat Aircraft (HAL)

[lookieloo]

You can always find that beating down LCA is a common agenda across all the threads here.Whether you go to Dassault RAFALE thread or PAKFA thread or J-20 thread or pretty much any other thread, you can always see people finding fault with LCA tejas.

So I reply to them in the vain hope that people won't do it further on any other thread.

I don't care. Basically, you're saying that the entire forum has to be your personal bully-pulpit for defending the LCA (which I don't find that interesting), allowing you to hijack any thread without regard to staying on topic.

Not sure why Kunal Biswas actively approves your conduct. BAD MODERATOR... BAD!!

 

[p2prada]

Why is everyone always talking about the LCA over here? Every time I see this thread getting bumped, I click hoping to see a new development on AMCA, only to get Rickrolled with more Tejas arguments.

AMCA will most probably be replaced with a 6th gen program before the decade. So that would help us keep up with the American plan for getting a 6th gen F-22 replacement between 2030-40. Meaning the AMCA project has been put on hold while Rafale and FGFA will cater to future needs that AMCA is supposed to handle.

I think IAF will be able to increase Rafale and FGFA numbers if AMCA is delayed by a decade while ADA will be able to complete LCA program in its entirety before AMCA 6G enters testing phase.

Quite interesting if you notice AMCA progressed from a Rafale type fighter in 2005-06 to a F-35/F-22 stealth level fighter in 2010 to most probably a 6th gen fighter in the next few years.

 

[Decklander]

The sea harrier is a sub sonic carrier based positive stability platform, What is it going to contribute to a discussion on thrust line and RSS airframe?
So you are not going to answer any questions regarding MIRAGE-lll vs MIRAGE-2000 and F-16 XL.
Doesn't matter.
When does Sea harrier achieve negative stability?

Let me answer your query now.
Even a blind man can make out where the CG of M3 is w.r.t its CP in vertical plane. In a low wing airplane the CG is above CP. One of the reasons for F-16XL to supercruise was its upward canted tail and downward engine nose. even in the case of Typhoon, it has been found that by tilting the thrustline by use of TVC in cruise will reduce the fuel consumption and provide better lift.
Sin3* for 98Kn thrust will provide a lift componant of approx 5KN and that too as part of nose pitch up. I hope you know how to resolve a parallelogram of vectors. Now at slow speeds the AOA is higher and CP lies close to CG in a stable ac. As the AOA reduces and speed increases, The CP moves back, the moment arm between the CG & CP increases and the drag rise due to higher speed needs higher thrust to overcome this drag rise. Which means that more and more thrust is available to overcome the nose down effect due to backward movement of CP. This obviates the need for use of stabilisers which add to trim drag to keep the nose up thereby reducing overall drag of the ac. At the same time the ac is able to accelarate much faster and can have higher mach speeds for same elevator authority.
In a RSS ac, the CG lies behind the CP, as the speed increases, the CP starts moving back and stage comes when it goes behind the CG making the ac stable. This is normally done at 0.9-0.95 mach. After that, a further increase in speed and lowering the AOA results in further back movement of CP giving a pronounced nose down movement to ac. This is particularly true about highly swept Talless Delta or cranked delta designs. To overcome this nose down movement, the elevons must move upwards to add to pitch up force to keep nose up. This reduces the overall lift as effective AOA due to this upward deflection of elevons, reduces the CL. A RSS ac must have either canards or tailplane or TVC to control this movement of CP by use of thrustline but in a stable ac as the nose up force required is directly proportional to the moment arm between CG & CP which is directly proportional to AOA and which is directly proportional to drag and that in turn is directly proportional to the thrust required. So for a stable ac using thrustline as a control surface, the vertical componant of the thrust at any stage of flight provides a pitch up force which is needed at that stage of flight. This remains true even when ac is loaded as the loading of stores adds to weight requiring higher AOA consequently higher thrust even though the moment arm of CG & CP in such a case is small due to higher AOA.
I will not like to answer any of your questions regarding the thrustline here anymore as you need to first study aerodynamics properly and also understand it in detail. I suggest that you buy,"Aerodynamics for Naval Aviators" and study it in detail. If you can understand it properly.

 

[Illusive]

AMCA will most probably be replaced with a 6th gen program before the decade. So that would help us keep up with the American plan for getting a 6th gen F-22 replacement between 2030-40. Meaning the AMCA project has been put on hold while Rafale and FGFA will cater to future needs that AMCA is supposed to handle.

I think IAF will be able to increase Rafale and FGFA numbers if AMCA is delayed by a decade while ADA will be able to complete LCA program in its entirety before AMCA 6G enters testing phase.

Quite interesting if you notice AMCA progressed from a Rafale type fighter in 2005-06 to a F-35/F-22 stealth level fighter in 2010 to most probably a 6th gen fighter in the next few years.

And the technology to develop critical systems for 6th gen aircraft, how will we develop something like this- Adaptive Versatile Engine Technology - Wikipedia, the free encyclopedia when we are having problems developing Kaveri. AMCA going for 6th gen would be unrealistic.

Quite interesting fact is that we haven't even finalized a design for AMCA even after a decade, its like LCA deja-vu.

 

[lookieloo]

AMCA will most probably be replaced with a 6th gen program before the decade. So that would help us keep up with the American plan for getting a 6th gen F-22 replacement between 2030-40. Meaning the AMCA project has been put on hold while Rafale and FGFA will cater to future needs that AMCA is supposed to handle.

I think IAF will be able to increase Rafale and FGFA numbers if AMCA is delayed by a decade while ADA will be able to complete LCA program in its entirety before AMCA 6G enters testing phase.

Quite interesting if you notice AMCA progressed from a Rafale type fighter in 2005-06 to a F-35/F-22 stealth level fighter in 2010 to most probably a 6th gen fighter in the next few years.

I do wish everyone would get off the 4G/5G/6G nonsense; fighter development is a bit more nebulous than cell-phones. Besides, there are no actual plans in the US for a direct F-22 replacement in the time-frame you mention. If there were, competing contractors for a fly-off would already be selected and prototypes would be under construction. What *6G* program are you referring to anyways? NGAD is just a USN effort to replace the Superhornet; and despite all the pretty marketing images by LM and Boeing, it's probably gonna be nothing more than a later-block F-35.

Also, are you saying the AMCA will be basically restarted as a more advanced project? That's actually rather sad. At some point HAL really needs to actually build something instead just upping their ambitions on paper.

 

[p2prada]

And the technology to develop critical systems for 6th gen aircraft, how will we develop something like this- Adaptive Versatile Engine Technology - Wikipedia, the free encyclopedia when we are having problems developing Kaveri. AMCA going for 6th gen would be unrealistic.

Quite interesting fact is that we haven't even finalized a design for AMCA even after a decade, its like LCA deja-vu.

This could very well be a major reason why AMCA may face delays. Engine.

Anyway we are yet to see which company is chosen for the engine development program with GTRE. One RFP was sent back in 2006 to P&W, Snecma and NPO Saturn, but that led to nowhere because one thing led to another and only Snecma stayed in a single vendor contract. So another tender will be sent.

Broadsword: Defence ministry goes global in search for Kaveri partner

Let's see what happens.

I do wish everyone would get off the 4G/5G/6G nonsense; fighter development is a bit more nebulous than cell-phones. Besides, there are no actual plans in the US for a direct F-22 replacement in the time-frame you mention. If there were, competing contractors for a fly-off would already be selected and prototypes would be under construction. What *6G* program are you referring to anyways? NGAD is just a USN effort to replace the Superhornet; and despite all the pretty marketing images by LM and Boeing, it's probably gonna be nothing more than a later-block F-35.

Yes, there is a F-22 replacement program. It is still in the early stages of RFI where feasibility studies will be conducted. Boeing is already conducting one for the SH replacement. Sure, we will need to wait for official confirmation, but,

https://www.fbo.gov/index?s=opportu...0c9c983f85e7952c2adc426b189&tab=core&_cview=1

The feasibility studies are ongoing.

Google "Miss February aircraft" and that will give you an idea. You can say we are in the early 80s when you compare to the F-22's development where companies are still doing feasibility studies and project definition, meaning USAF will have to wait for at least half a decade more before a RFP can be made.

Also, are you saying the AMCA will be basically restarted as a more advanced project? That's actually rather sad. At some point HAL really needs to actually build something instead just upping their ambitions on paper.

No, it isn't. We will need to keep up during the timeframe we are speaking of, we may end up putting more money into defense than the US can in another 15 years.

Anyway, AMCA will be ADA's project. FGFA will be HAL's. ADA is under DRDO and is an R&D unit. HAL is an independent organization, and does R&D and manufacturing. HAL or possibly a private company may manufacture anything that ADA may come out with.

 

[Crusader53]

Personally, I think a delay with the AMCA Program is not a bad thing at all. As much of the current 5th Generation Technology needs to mature more. Then India will be in a better place on what is needed for the AMCA. As I've said all along India needs to think 6th Generation not 5th Generation. Also, unlike the PAK-FA India will be in on the ground floor too!

 

[ersakthivel]

I don't care. Basically, you're saying that the entire forum has to be your personal bully-pulpit for defending the LCA (which I don't find that interesting), allowing you to hijack any thread without regard to staying on topic.

Not sure why Kunal Biswas actively approves your conduct. BAD MODERATOR... BAD!!

don't you find it odd that in AMCA forum people are dragging LCA needlessly?

That too with stupid aeronautical theories like Relaxed stability fighter is a repeatedly Sold Shit, and a tactic used by US to dumb costly stuff on other country's airforces.The guys who are gunning here for LCA in AMCA thread have no proof other than their wild imaginative spurious claim to back it.

Why is that?

In a forum every person is entitled his views as long as one guy doesnot abuses other with foul language and backs his claim with authentic source.

When people post what they feel about LCA , I post what I feel quoting source.That's why Kunal Biswas approves it. If I am throwing unsubstantiated statements and wishful thinking to bolster prejudiced view points like Tejas is an unmitigated disaster He wouldn't approve of it. So he Looks like a good MOD to me.

Report to MODs to stop discussing LCA in AMCA thread. And I am too glad to comply with it , if all other so called defence pros adhere to it.

 

[Bhadra]

Now that LCA bread is almost exhausted so DREDO and HAL need a new source of income from AMCA

Papi pet ka sawal hai !!

 

[ersakthivel]

I rest my case as you seem to have bcum dogmatic with hardly any knowledge of ac design stability. You are stuck on RSS without realising that the trend now has gone back to stable design as the need for ITR and STR are no more a factor with advent of all aspect missiles which like MICA can shoot down a target 180* behind while the ac is flying straight without the need to turn. You probably have not even heard of HMD guidance wherein the ac need not even use its ITR or STR.
Buddy, you are still in 2013 BC while the aircombat has moved to 2013 AD.

I know all about high offboresight HMDS-DASH air to air missiles that doesnot need fancy STRs any more , as I myself has posted it moths before you became a member here.

If you want to discuss stuff about LCA do it in that thread.Or if you want to discuss Why Relaxed Static Stability airframe fighters are not needed any more and a waste of tax payer money , please open another thread dedicated to that.We will discuss it.

DOn't discuss RSS and LCA in AMCA thread. As other posters are feeling suffocated.

Thanks.

 

[ersakthivel]

Now that LCA bread is almost exhausted so DREDO and HAL need a new source of income from AMCA

Papi pet ka sawal hai !!

We will discuss the sorry state of exhausted LCA bread in LCA thread, where you are yet to make a single post.

Not here,

Thanks.

 

[ersakthivel]

Let me answer your query now.
Even a blind man can make out where the CG of M3 is w.r.t its CP in vertical plane. In a low wing airplane the CG is above CP.

The same blind man can make out that the inability of the Positive Static Stability config's low thrust line and CG above CP combination alone to give high AOA , highly agile,high alpha performance at close combat maneuvering corner speeds, which are typically well below 0.95 mach ,

That's why the same blind men of Dassault went for RSS that is CG behind CL in mirage -2000 to achieve exceptional handling at low speeds , and quick nose pointing ability at corner speeds , which will enhance the use of HMDS-DASH High offboresight dual seeker missiles.Note that Mirage-2000 was controllable with an AOA of 28 deg at airspeeds at the intro airshow.

That was due to CG behind CL RSS set up. NOT DUE TO CG BELOW CL STABLE FLIGHT PROFILE SETUP.

One of the reasons for F-16XL to supercruise was its upward canted tail and downward engine nose. even in the case of Typhoon, it has been found that by tilting the thrustline by use of TVC in cruise will reduce the fuel consumption and provide better lift.

And the same blindman can also easily comprehend that that the reason for the exceptional handling of F-16 XL is not just due to the upward canted tail and downward engine alone.

F-16 XL is an evolution of Relaxed Static Stability- F-16 high agility airframe design.With a much bigger exceptionally lower wing loading CRANKED DELTA wing form as Tejas , weighing twice more ,



This beneficial Lift to drag ratio provided by the low wing loading ,huge wing delta wing like the LCA (accused by you for high drag due to high wetted area of the huge delta wing.) also the reason that it can deliver 40 percent more weapon loads at twice the distance of normal F-16 with improvement in every performance spec.

And that is the reason for it's exceptional buffet free performance , impressive low speed handling ability and it's impressive ability to pull more Gs with less time needed than the F-16 A/B.

It was primarily due to the impressive Highly beneficial LIFT to DRAG ratio , provided by the huge wings, which resulted in better performance in all flight envelopes regardless of the higher so called drag all you guys are stressing about.
[/B]

Sin3* for 98Kn thrust will provide a lift componant of approx 5KN and that too as part of nose pitch up. I hope you know how to resolve a parallelogram of vectors. Now at slow speeds the AOA is higher and CP lies close to CG in a stable ac. As the AOA reduces and speed increases, The CP moves back,

Of course your point that CP moves back in at higher speed supersonic flight ,is explained in the official website of RSS fighter TYPHOON in a much simpler manner.

That is why it become less maneuverable at high supersonic speeds, the reason exactly being their transition into Positive static stability config from the highly agile Relaxed static Stability config.

The reason why every fighter after Mirage is an RSS is the need for high AOA , high ITR at CORNER SPEEDS which are well below the 0.95 mach, where most of the critical close combat maneuvers are effected.


You and may hold the view that MICA and DASH has made close combat corner speeds is extinct. But the very name FIGHTER PLANE implies it should have the ability to give a good account of itself at the 0.5 to 0.95 mach close combat speeds. Otherwise it will be called a simple interceptor which flies from A to B delivering just Missiles.

You may have known that 90 percent of the time a fighter flies is in this 0.5 to 0.95 mach speeds where the RSS -negative stability airframe excels in close combat maneuver.IF it continuously fly in supersonic speeds alone it's range and manuevering ability will be drastically curtailed.

And 200 deg temp of the airframe of the Fighter in continuous Supersonic Flight is a magnet for Passive heat seeking missiles, opposed to 40 to 60 deg airframe temp of the fighter flying continuously in subsonic speeds, which won't advertise it's presence to enemy's passive infra red seeker faraway attracting counter measures like a magnet.

the moment arm between the CG & CP increases and the drag rise due to higher speed needs higher thrust to overcome this drag rise. Which means that more and more thrust is available to overcome the nose down effect due to backward movement of CP. This obviates the need for use of stabilisers which add to trim drag to keep the nose up thereby reducing overall drag of the ac. At the same time the ac is able to accelarate much faster and can have higher mach speeds for same elevator authority.


In a RSS ac, the CG lies behind the CP, as the speed increases, the CP starts moving back and stage comes when it goes behind the CG making the ac stable. This is normally done at 0.9-0.95 mach. After that, a further increase in speed and lowering the AOA results in further back movement of CP giving a pronounced nose down movement to ac.

This is particularly true about highly swept Talless Delta or cranked delta designs. To overcome this nose down movement, the elevons must move upwards to add to pitch up force to keep nose up.

THIS nose down momentum will be twice more in Static Stability Fighter is the point(since their CG is much in front of RSS fighter) , you conveniently ignore.

You should note that only CL moves back at supersonic speeds, NOT CG.

So you can calculate the extra nose down momentum penalty in Positive Static Stability fighter (which have their Cg much further in front than the highly swept Talless Delta or cranked delta design RSS fighter, due to much higher moment arm between the CG & CP increase resulting in a much bigger nose down momentum.)

This reduces the overall lift as effective AOA due to this upward deflection of elevons, reduces the CL. A RSS ac must have either canards or tailplane or TVC to control this movement of CP by use of thrustline but in a stable ac as the nose up force required is directly proportional to the moment arm between CG & CP

Due to the CG situated much further in front the moment arm between Cg and CL will be much much higher in Positive Static Stability fighter than the RSS huge cranked delta wing fighter like Tejas.

So when you talk about the so called 5kn lift advantage for Positive Static stability low thrust line fighter , You should equate it with the much higher nose down moment arm between CG & CP penalty of the low thrust line -Positive Static Stability Fighter

which is directly proportional to AOA and which is directly proportional to drag and that in turn is directly proportional to the thrust required. So for a stable ac using thrustline as a control surface, the vertical componant of the thrust at any stage of flight provides a pitch up force which is needed at that stage of flight.

But a stable ac using thrustline as a control surface, has a much, much bigger nose down moment arm between CG & CP penalty all the time,more so at supersonic flight

This remains true even when ac is loaded as the loading of stores adds to weight requiring higher AOA consequently higher thrust even though the moment arm of CG & CP in such a case is small due to higher AOA.


I will not like to answer any of your questions regarding the thrustline here anymore as you need to first study aerodynamics properly and also understand it in detail. I suggest that you buy,"Aerodynamics for Naval Aviators" and study it in detail. If you can understand it properly.

F-16 XL too seems to have the same mid mounted wing arrangement of tejas, Where is the proof of it's low thrust line?
http://www.airforcemag.com/MagazineArchive/Pages/1983/November 1983/1183f16xl.aspx


You need not answer any questions regarding Thrust line here any more , as I have no doubts about it, While it may be beneficial at some flight envelope, it cannot replace the RSS config is my idea.
SO We can discuss all these things in a separate RSS(negative Static Stability) vs LOW thrust line Positive Static Stability thread without suffocating other posters.

 

[ersakthivel]

I rest my case as you seem to have bcum dogmatic with hardly any knowledge of ac design stability. You are stuck on RSS without realising that the trend now has gone back to stable design as the need for ITR and STR are no more a factor with advent of all aspect missiles which like MICA can shoot down a target 180* behind while the ac is flying straight without the need to turn. You probably have not even heard of HMD guidance wherein the ac need not even use its ITR or STR.
Buddy, you are still in 2013 BC while the aircombat has moved to 2013 AD.

The Revolutionary Evolution of the F-16XL

For a decade and a half, many fighter tacticians have stressed the paramount importance of being able to sustain a high turn rate at high Gs. The rationale was that with such a capability, enemy aircraft that cannot equal or better the sustained turn rate at high Gs could not get off a killing shot with guns or missiles.


With developments in missiles that can engage at all aspects, and as a result of having evaluated Israeli successes in combat, the tacticians are now leaning toward the driving need for quick, high-G turns to get a "first-shot, quick-kill" capability before the adversary is able to launch his missiles. This the F-16XL can do. Harry Hillaker says it can attain five Gs in 0.8 seconds, on the way to nine Gs in just a bit more time. That's half the time required for the F-16A, which in turn is less than half the time required for the F-4. The speed loss to achieve five Gs is likewise half that of the F-16A.


All of these apparent miracles seem to violate the laws of aerodynamics by achieving greater range, payload, maneuverability, and survivability. Instead, they are achieved by inspired design, much wind-tunnel testing of shapes, exploitation of advanced technologies, and freedom from the normal contract constraints.


The inspired design mates a "cranked-arrow" wing to a fifty-six inch longer fuselage. The cranked-arrow design retains the advantages of delta wings for high-speed flight, but overcomes all of the disadvantages by having its aft portion less highly swept than the forward section. It thus retains excellent low-speed characteristics and minimizes the trim drag penalties of a tailless delta.


Although the wing area is more than double that of the standard F-16 (633square feet vs. 300 square feet), the drag is actually reduced. The skin friction drag that is a function of the increased wetted (skin surface) area is increased, but the other components of drag (wave, interference, and trim) that are a function of the configuration shape and arrangement are lower so that the "clean airplane" drag is slightly lower during level flight, and forty percent lower when bombs and missiles are added. And although the thrust-to-weight (T/W) ratio is lower due to the increased weight, the excess thrust is greater because the drag is lower – and excess thrust is what counts.


The larger yet more efficient wing provides a larger area for external stores carriage. At the same time, the wing's internal volume and the lengthened fuselage enable the XL to carry more than eighty percent more fuel internally. That permits an advantageous tradeoff between weapons carried and external fuel tanks.

Where does it say the F-16XL's magical handling abilities are due to Positive Static Stability , Low thrust line config, as you are repeatedly implying?

It only says that all the performance of F-16XL is due to the fact that it had an inspired cranked arrow delta design which was followed in tejas, and not due to any Positive Static Stability , Low thrust line config.

F-16 XL too has no canards and no thrust vectoring . You insisted that to get the most of the tail less delta design a fighter should have a Canard or TVC, but F-16 XL has none of these.

 

[ersakthivel]

To say that all the advantages of AMCA can be had in FGFA and RAFLE is not correct.

AMCA will have far lower RCS than the RAFALE and FGFA,

AMCA numbers are critical for IAF to achieve the golden gaol of all 5th gen fighter force, since the FGFA won't be as stealthy as F-22 or even F-35.

To say that AMCA project has been postponed or delayed , the bare minimum we need is an official communique from HAL or IAF or ADA or DRDO or MOD or GOI with the name of the person who is issuing it.

A reporter quoting unnamed defence minister official does not look like a credible reason to believe that AMCA project has been stopped .

 

[Decklander]

@ersakthivel,
You have no idea of what you are posting here and you have absolutely no idea of what is the meaning of CG being above CP or use of thrustline.
Will you shut the bloody F**K if I give you the proof of F-16xl thrustline?

You are novice to this world and you are harping on things you have no clue about. Power or thrust can also have a destabilizing effect in that an increase of power may tend to make the nose rise. The aircraft designer can offset this by establishing a "high thrust line" wherein the line of thrust passes above the CG as power or thrust is increased a moment is produced to counteract the down load on the tail. On the other hand, a very "low thrust line" would tend to add to the nose-up effect of the horizontal tail surface. This is what was applied in M3 and M2K. wherein the partial pitch moment of RSS was offset by thrustline use.
The CG of an aircraft exists in three dimensions. It's position not only effects the balance of the aircraft, but how the aircraft reacts when power is applied or reduced. A thrust line above or below the longitudinal axis creates different behavior during power changes, mostly in the pitching moment about the lateral axis.
A simple application of Newtons Law (which ignores some other effects) says the if the thrust line is above the CG, the nose will pitch down when power is added, and up when power is reduced. If the thrust line is below the CG, the effect is opposite. Think of it like a rope being around your neck, your waist, or your feet and what would happen to your balance when it is suddenly tugged by someone in front of you. If around your neck, you'd pitch forward and fall face down. If your feet, you'd pitch face up and land on your back. If around your waist, you'd maintain your balance. Same basic effect in an airplane. It is actually quite a bit more complicated than that. First is the issue of whether the center of thrust (different from the centerline of thrust) is ahead or behind the CG. There is also the issue of whether the thrust line is parallel to the longitudinal axis, or if it is slightly offset, above, below, or to one side. Designers vary these things to obtain the desired handling characteristics or to serve other more important needs. If you set a centre line, then set the elevator to 0 degrees, then for positive stability, you need the wing to have a positive incidence, with a lifting air foil, the CG below the wing, and if the thrust line is on the same line, you need down thrust. If you set the engine to 0 degrees, when you open the throttle, the airframe will tend to loop. With down thrust, it wil pull the nose down when power is increased, so you will stay in level flight. If the thrust line is above the CG, the engine needs less down thrust. If the thrust line is below the CG, the engine needs more down thrust. The relation between the thrust line and the CG depends on the nose moment, which is the distance between the CG location and the point at which the thrust acts. The longer the nose moment is, the longer the effective lever is, and the less shift in thrust line is needed.

You have learnt just three letters about stability and design of an aircraft R S S and you think that you have mastered it all. Can please explain to me as to how RSS helps in SUSTAINING high AOA? What use are vortex generators or LERX if RSS cud do it all for F-16? I suggest that you read something more than wiki and more advanced rather than rely on articles which you can't even understand. All this while I have been discussing about higher and lower thrustline while you are hung on RSS.

 

[ersakthivel]

@ersakthivel,
You have no idea of what you are posting here and you have absolutely no idea of what is the meaning of CG being above CP or use of thrustline.
Will you shut the bloody F**K if I give you the proof of F-16xl thrustline?

The language you used here shows the kind of dumbass you are faking to be a know all.Who the f**k is needed to show proof about F-16 Xl's thrust line . A troll like you or me?

Who advanced the spurious argument that F-16 Xl's low thrust line and not the fantastic low wing loading cranked delta RSS airframe being the reason behind it's stupendous performance?

It is you.NOT ME. Before asking me to show proof about F-16 XL thrust line get it into your air tight head that you are the one who advanced this F**King argument. Not me.

I just quoted that what the designer of the F-16 XL saying that,","F-16 Xl's fantastic low wing loading cranked delta RSS airframe being the reason behind it's stupendous performance and not the low thrust line"".

This is the accepted norm for posting in open forum.Know the damned rule first.If you cannot quote any credible web site for your defense, Don't lunge on the person doing exactly that like a rabis infested dog.

There are legions of retards roaming the net sprouting foolish theory. I don't have time to argue with proficient BS posters.

You are novice to this world and you are harping on things you have no clue about. Power or thrust can also have a destabilizing effect in that an increase of power may tend to make the nose rise. The aircraft designer can offset this by establishing a "high thrust line" wherein the line of thrust passes above the CG as power or thrust is increased a moment is produced to counteract the down load on the tail. On the other hand, a very "low thrust line" would tend to add to the nose-up effect of the horizontal tail surface. This is what was applied in M3 and M2K. wherein the partial pitch moment of RSS was offset by thrustline use.

yeah, I have seen it all being explained with three figures of a prop driven aircraft with three illustrations, with three vector lines indicating center of lift,center of gravity and a down load on the tail. it is no rocket science beyond my comprehension.

Just think about whether those three illustrations on which you place your entire faith have any relation to the cranked delta tail less RSS layout. Those illustrations are done to explain the pros and cons of wing arrangement of classic positive static stability fighters of yore.

Don't imagine yourself to be Newton and Einsteen combined after explaining these mundane class -I lessons to me.

Aircraft designing is a holistic science, not faking a few useless argument.All forces that act on the F**king thrust line should act through the center of lift or pressure which is the cumulative point which focus's the lift force which is planned in front of the CG in RSS airframe.That is what the difference between Mirage-III and Mirage-2000, and not any other BS you expound here.

It is not stated by something a hothead like you who posts BS clothed as knowledge. this. It is the authoritative science called Aerodynamcis.

The CG of an aircraft exists in three dimensions. It's position not only effects the balance of the aircraft, but how the aircraft reacts when power is applied or reduced. A thrust line above or below the longitudinal axis creates different behavior during power changes, mostly in the pitching moment about the lateral axis.


A simple application of Newtons Law (which ignores some other effects) says the if the thrust line is above the CG, the nose will pitch down when power is added, and up when power is reduced. If the thrust line is below the CG, the effect is opposite.

The basic postulate of aerodynamics is that any thrust on the thrust line is to act through the center of LIFT or center of pressure and nothing else. RSS airframe deals with this theory and fixes the position of the CG behind the CP or CL in subsonic and trans sonic flight to achieve super agility. Rest of the BS like TYPHOON has lower thrust line , mirage has lower thrust line is known to any kid.

Only a hero like you can dodge accepting simple facts like and go on posting your own fancy BS like F-16 XL's lower thrust line is the sole reason for it's superlative performance.

And finally when proved otherwise brazenly asking the other guy for proof of F-16 XL's thrust line!!!!!!!!!!!!!!!!!!!

Think of it like a rope being around your neck, your waist, or your feet and what would happen to your balance when it is suddenly tugged by someone in front of you. If around your neck, you'd pitch forward and fall face down. If your feet, you'd pitch face up and land on your back. If around your waist, you'd maintain your balance. Same basic effect in an airplane.

These rope trick and tugging are based on the premise that a person is planted on the ground with his feet and the rope is tied in a fixed point on the pole . But a fighter is a free body floating in the air with force couple between the CG , CP and the act of all the control surfaces to configure all these into useful flight.No one drives a nail through the Cg of the fighter so you can tug with your thrust line on it.

If lift force produces an upward moment . the Cg produces a downward moment that's all. By placing CG behind the CL a nose up momentum is produced and maintained. As simple as that.

All the force that acts on the thrust line should act through the cumulative point called center of lift.

If this center of lift is placed behind the CG (in a positive static stability config ) there is no F***king way to avoid a downward momentum that will certainly be caused by the CG which lies in front of CP or CL.

It is actually quite a bit more complicated than that. First is the issue of whether the center of thrust (different from the centerline of thrust) is ahead or behind the CG.

DOES THE FORCE ALONG THE THRUST LINE ACT THROUGH THE CENTER OF LIFT (which is the point of focus of cumulative lift produced by all the control and lifting surfaces )OR NOT?
Contemplate it and you will have all the answers to yourself.

There is also the issue of whether the thrust line is parallel to the longitudinal axis, or if it is slightly offset, above, below, or to one side. Designers vary these things to obtain the desired handling characteristics or to serve other more important needs. If you set a centre line, then set the elevator to 0 degrees, then for positive stability, you need the wing to have a positive incidence, with a lifting air foil, the CG below the wing, and if the thrust line is on the same line, you need down thrust. If you set the engine to 0 degrees, when you open the throttle, the airframe will tend to loop. With down thrust, it wil pull the nose down when power is increased, so you will stay in level flight. If the thrust line is above the CG, the engine needs less down thrust. If the thrust line is below the CG, the engine needs more down thrust. The relation between the thrust line and the CG depends on the nose moment, which is the distance between the CG location and the point at which the thrust acts.

What is the relation between the center of lift and the thrust line?

If the forces along the thrust line act through center of LIFT or NOT?

If they act then the logic of RSS is unbreaable. No amount of waffling will change that.

The longer the nose moment is, the longer the effective lever is, and the less shift in thrust line is needed.

You have learnt just three letters about stability and design of an aircraft R S S and you think that you have mastered it all.

Just learn that wherever the thrust line is all the force along the line should act through the center of lift. And you will get it easy.

That is why all modern multi role high agility fighters like M2K,TYPHOON, RAFALE, F-16 ,tejas,grippen, F-22,F-16 Xl are all low wing loading tail less delta either with a CRANK or COMPOUND or LREX or CANARD or Diamond shaped wing RSS airframe irrespective of the fact where the hell their thrust line is. The objective of the crank or canard or lrex or compound delta is to create lift inducing vortices and delay the onset of stall to increase the aerodynamic efficiency of the wing at close combat corner speed High AOA dog fight maneuvers.

Can please explain to me as to how RSS helps in SUSTAINING high AOA? What use are vortex generators or LERX if RSS cud do it all for F-16? I suggest that you read something more than wiki and more advanced rather than rely on articles which you can't even understand. All this while I have been discussing about higher and lower thrustline while you are hung on RSS.

I am done with explaining all the BS. No more.
At last you are revealing what

 

[ersakthivel]

So if people want to argue on RSS they can open their own thread on it and don't post freaking BS on other threads.

 

[ersakthivel]

The Revolutionary Evolution of the F-16XL

All of these apparent miracles seem to violate the laws of aerodynamics by achieving greater range, payload, maneuverability, and survivability. Instead, they are achieved by inspired design, much wind-tunnel testing of shapes, exploitation of advanced technologies, and freedom from the normal contract constraints.


The inspired design mates a "cranked-arrow" wing to a fifty-six inch longer fuselage. The cranked-arrow design retains the advantages of delta wings for high-speed flight, but overcomes all of the disadvantages by having its aft portion less highly swept than the forward section. It thus retains excellent low-speed characteristics and minimizes the trim drag penalties of a tailless delta.

The above is the reason for the superlative performance of the F-16 Xl. Not any freaking thrust line!!!!!!!!!!!!!!!

Although the wing area is more than double that of the standard F-16 (633square feet vs. 300 square feet), the drag is actually reduced. The skin friction drag that is a function of the increased wetted (skin surface) area is increased, but the other components of drag (wave, interference, and trim) that are a function of the configuration shape and arrangement are lower so that the "clean airplane" drag is slightly lower during level flight, and forty percent lower when bombs and missiles are added. And although the thrust-to-weight (T/W) ratio is lower due to the increased weight, the excess thrust is greater because the drag is lower – and excess thrust is what counts.

 

[Decklander]

The Revolutionary Evolution of the F-16XL

You lack very basic knowledge has further been proven by what you have posted. Let me ask you what will be the diff in flying charactersticks of a non delta design with lesser sweep back having similar wing area as F-16xl when compared to your famous design of cranked delta?
what is it that cranked delta overcomes when compared to with other delta designs?
Which wing plan form will have more internal fuel volume, a cranked delta or normal swept back wing for similar wing area?
Was their any comparision made of the flying qualities of F-16xl w.r.t anyother ac other than that of F-16?
Why is it that no such ac has been built by US companies till date while after F-16xl testing they had made atleast ten more ac prototypes and non of them had cranked delta design?
Why did HAL change from original cranked delta to compound delta design?
What are the short comings of cranked delta w.r.t air combat?

Regarding RSS, you need to explain other than higher pitch up rate, what other benefit does RSS offer especially when compared to canard designs? You also need to explain as to how does RSS help in maintaining high AOA?
Can you pls elaborate that between 0.5m to 0.95m wherein most ac are negatively stable, what happens to the fuel burn and what design penalties come into effect?
What use does ITR have in todays aircombat wherein you have missiles like Python-5 and also targetting system like SPECTRA which have shot down targets flying behind them without the need to turn at all?
What role does ITR play a in true BVR launch? Does RSS have any use their? Why was F-16 made and what were the reasons that it was given RSS?
Lastly can you fly any RSS ac once its FBW fails for any reason?

 

[ersakthivel]

You lack very basic knowledge has further been proven by what you have posted. Let me ask you what will be the diff in flying charactersticks of a non delta design with lesser sweep back having similar wing area as F-16xl when compared to your famous design of cranked delta?

The leading edge of the delta wing will not contact the shock wave cone that has to be encountered by the normal simple swept back wings. This ensures that delta wing has a laminar airflow available to it to generate lift and function with high aerodynamic efficiency which cannot be done by simple swept back wings that has to encounter the turbulent airflow at trans sonic shock waves.


The high rearward sweep back angle lowers the airspeed normal to the leading edge of the wing, which ensures that the wing remains aerodynamically efficient at at high subsonic, transonic, or supersonic speed, because the speed of air perpendicular to leading edge will be lower than the speed of sound ensuring laminar air flow bereft of shock wave while the over wing speed of the lifting air is kept to less than the speed of sound.

The delta plan form gives the largest total wing area for the wing shape, with very low wing loading, giving high maneuverability and beneficial lift to drag ratio to a fighter , remember the F-16 XL.


the leading edge of the wing produces stall delaying , lift inducing vortices at high angle of attack(ev)

it also gives large internal volume and sturdy wing design.


The problem in the plain tailless delta designs, is loss of total available lift caused by turning up the wing trailing edge or the control surfaces (as required to achieve a sufficient stability) and the high induced drag of this low-aspect ratio type of wing.


This causes plain delta-winged aircraft to 'bleed off' energy very rapidly in turns, a disadvantage in aerial maneuver combat and dogfighting.

It also causes a reduction in lift at takeoff and landing until the correct angle of attack is achieved, this means that the rear undercarriage must be more strongly built than with a conventional wing.

Pure delta-wings faced these problems like flow separation at high angles of attack (swept wings have similar problems), and high drag at low altitudes, due to denser air..

what is it that cranked delta overcomes when compared to with other delta designs?

compound delta,or double delta or cranked delta ,with two different sweep back angles , makes the creation of stall delaying high-lift inducing vortex in a more controlled fashion, countering the effect of the high drag typical of old plain deltas, giving the cranked delta acceptable slow speed specs and more control at slow speeds..

These vortices cancel out the bleed off in energy typical of the old plain deltas, because they increase lift and gives it a
highly beneficial lift to drag ratio cancelling out the higher drag of low aspect ratio plain deltas.

l Also it retains these large vortices in high AOA delaying the formation of flow separation ad postpones the onset of stall.

Which wing plan form will have more internal fuel volume, a cranked delta or normal swept back wing for similar wing area?

cranked delta has a bit lesser wing area than full delta ,for having better flying specs. But it will still do better than normal swept back wing.

Was their any comparision made of the flying qualities of F-16xl w.r.t anyother ac other than that of F-16?

F-16 XL was an evolution of F-16 design, which did much much better than the plain vanilla F-16 proving the superiority of cranked or compound delta wing form.The results paved the way for compound delta (like a diamond) wing form of the F-22. If yo still have any doubt look at the difference between SU-30 MKI wing form and FGFA wing form.

Why is it that no such ac has been built by US companies till date while after F-16xl testing they had made atleast ten more ac prototypes and non of them had cranked delta design?

At that time the F-15 which was a much bigger twin engine fighter with lot higher TWR , and higher powered RADAR and weapon load was also available to USAF. The non induction of F-16 XL was due to these factors clearly explained in the link I posted, and not due to the cranked delta design.

Why did HAL change from original cranked delta to compound delta design?

the much larger fighter that F-16 was enabled it to carry double crank of the delta wing form (cranked arrow) which allowed it to have a large area of vortice generation at two separate places in the wing.

And F-16 XL was just the expansion of the cropped delta of F-16 which had LREX at wing root. Not a new design So they converted the LREX to crank and added another bigger crank at the wing tip.

SInce Tejas was a new design it does not have to go thorough the contortions of double crank and straight away went with the big crank with a twist at wing root to enable large vortices generations at wing root passsing over the large delta wing area energizing lift over the entire wing.

What are the short comings of cranked delta w.r.t air combat?

Your turn to expound on that.

Regarding RSS, you need to explain other than higher pitch up rate, what other benefit does RSS offer especially when compared to canard designs? You also need to explain as to how does RSS help in maintaining high AOA?

i have explained it all along .better nose pointing authority, higher instantaneous turn rate vital for nose up lock ons with DASH-HMDS , high off boresight missiles. overall beneficial high lift to drag ratio.RSS exploits the naturally better ITR of delta wing forms even further.

Can you pls elaborate that between 0.5m to 0.95m wherein most ac are negatively stable, what happens to the fuel burn and what design penalties come into effect?

Mot of the time a fighter flies at the air speed optimized for lower fuel burn and low drag according to it's design. But when it comes to close combat the better agility of the RSS cranked or compound delta wing form gives more chances to the pilot with high ITR and exceptionally low wing loading leading to better lift for high AOA , high alpha maneuvers which is further sharpened by RSS airframe.

What use does ITR have in todays aircombat wherein you have missiles like Python-5 and also targetting system like SPECTRA which have shot down targets flying behind them without the need to turn at all?

A fighter needs to be a fighter at first in it's clean config with super agility. using Pythons come much later.

What role does ITR play a in true BVR launch? Does RSS have any use their? Why was F-16 made and what were the reasons that it was given RSS?

ITR gives the quick nose pointing ability for python type WVR missiles. of course if missile has duel seeker infra head this ITR is not needed. But infra seeker is supplemented with radar seeker or guidance from mother craft to ensure better kill rates. That's where the high ITR comes into play.

Lastly can you fly any RSS ac once its FBW fails for any reason?

If you clarify whethe you can fly a conventional plane after the loss of all hydraulic fluids I will also clarify.