JF-17/FC-1 Fighter Aircraft thread

[mean_bird]

OK, so it is at the same status the LCA is in. First 40 to be vanilla, while the remaining ones with western engine and French Meteor or Derby. Negotiations are on.

I do not wish to start a comparison thread here but no, they are not. The Tejas have some major problems to solve relating to AoA, pulling high g maneuvers, its massive overweight problem, etc

Radars or other avionics can be and have been upgraded on many aircrafts IF (and a big if) they choose to do so (e.g F-16, F-15 with AESA, etc). The JF-17 was specifically designed by de-linking the avionics from the airframe so upgrading them (if necessary) won't be a problem. But you cannot upgrade a plane to reduce its weight...its gonna remain like that.

Strangely enough, I haven't read or heard one PAF personal claim the engines to be underpowered ( I do not claim to have read everything so any counter-proof is welcome). The only thing I have heard them say is

1. Its Russian so they need support during difficult times, and most importantly( and repeatedly)
2. Russian engines have bad serviceability.

This shows how you have confused span and sweep. Aspect ratio depends on the span; for a given span, you can have many angles of sweep and consequently different wing shapes and designs. The tailing edge can also be swept or not.

Read up more on this.

I opine that, that's what has been done on the JF-17. Just look at the shapes from the top of F-16 and JF-17, they are very similar.

You are going by definitions but all these things are inter-related...you can't look at them independently. For example, a glider(high aspect ratio, little to no sweep) and the discovery shuttle design (low aspect ratio) will always be radically different.

The sweep angle does have proportionality with the aspect ratio if you want a certain behavior.

No. An F-16 uses flaperons, which are not airelons. Looking at the near exact wing shapes of the F-16 and JF-17, I'd like someone to confirm whether JF-17also has the typical flaperons.

A flaperon performs the action of a a flap and an aileron in one structure... I don't see what difference it makes?

[SteelBird]

Strangely enough, I haven't read or heard one PAF personal claim the engines to be underpowered ( I do not claim to have read everything so any counter-proof is welcome). The only thing I have heard them say is

1. Its Russian so they need support during difficult times, and most importantly( and repeatedly)
2. Russian engines have bad serviceability.

It's strange enough, from what I've read about the JF-17. PAF wants to replace the RD-93 with the M88. RD-93 is said have thrust of 49.4 KN dry and 84.4 KN with afterburner, while M88 has 50.04 KN and 75.62 KN respectively. If RD-93 is considered underpowered, isn't the M88 even more underpowered? However, the latest version M88-Eco claims to have >90 KN, but it's only available after 2010. PAF is going to have this?

[Londo Molari]

JF-17 was built around the RD-93.
The WS-13 is built for the JF-17.

Other than those 2 engines, I don't see how any other engine could be used. I would expect the French M88 would have different dimensions, and its interface connections would be in different positions, so in my opinion it is not and never was an option.

[Indianfighter]

WRONG Start reading up on the books. Its computed differently based on wing design.

For deltas and diamonds, aspect ratio is a ratio between wing span and wing root /2. That's why its called a ratio for god sakes. For planes with a constant chord its the ratio between the wing span / chord; if the wing has a variable chord, determine the average or mean chord, then wing span / avg. chord.

The sweep is the hypotenuse of the triangle between X= length of Wing Root, and Y = width of wing span.

If you're using different wing designs like trapezoidal or diamond, the calculations for sweep are different.

But we are talking of deltas and clipped deltas here which has strong advantages for use in fighter designs due to their **superior** rigidity, load transfer and stress handling qualities over sweep wings.

Whoever was talking of pure deltas or trapezoids ? (you have a sure propensity to skid off the main topic and start talking something else).

The MAC of a simple delta is simply root length by 2. For a cropped one, the standard MAC equation will still be used, which is a simple integral of a function of the co-ord of the wing's edge. This is independent of any sweep or hypotenuse or whatever.

Now answer this : Do you see the sweep variable in ANY equation of aspect ratio presented by you or me so far ? It means that it is independent of the aspect ratio and given an aspect ratio, you can have other sweeps : delta (cropped or not) or non-delta (like Fulcrums). Then you'll understand the folly of your logic.

Which means nothing really, because that's all all clipped deltas and deltas look.

Look at the shapes of the Mirage III and the Delta Dagger.

I contend : Not only the cropped delta wing with flaperon, even the cropped delta alone is visible only in the F-16. No other 4th or 4.5 G fighter aircraft has a cropped delta wing. The JF-17 has virtually copied all of it + I recon even the flaperon configuration.

That shows you how little you don't know. Maximum speed is not about optimum flight regime. The flight regime is the what is the most common speed and altitude you expect the plane to engage or do its duties. No one flies at max speed all the time.

Wrong here again. You assume your flight regime based on your mission and operational roles.

The flight regime is not just decided by speed and altitude which you mistakenly claimed earlier, but by the size of the aircraft and loads carried primarily. All aircraft from FC-1 to J-11 don't fly at top speeds and top g's all the time but they do have similar speeds at which they'll fly most of their missions. Since they weigh differently and carry varying loads, they have to be designed differently.

The JF-17 DO NOT share any commonality in their weights and loads carried. Yet, they happen to have an uncannily similar wing structure (though this does not mean that different aircraft must have different wing structures).

This is NOT an indictment of the FC-1. If it has the F-16's wings and a relatively new western concept like DSI and flies well, it is well and good. No need to take offence. A flaperon is also not an airelon (it's toward the fuselage, unlike the airelon with is away from it). It is also present on the leading edge. Looking at the images of FC-1, it also has flaperon-like contours.

Now you don't know what is the difference between a fixed intake and a variable intake? The fixed intake is designed as the best compromise and balance for the most common operational and flight mission regimes of the aircraft. The variable intake is designed with the maximum speed, then determine the angles of the variable ramp to control the air flow at different airflow requirements using an air flow sensor and computer.

Even from the beginning, the J-7 actually uses a variable intake---the nose inlet actually slides back and forth, and compared to the standard MiG-21, it has more stepping increments. The JF-17 has always been fixed to start with. When you got a fixed inlet, the exact dimensions are precisely calculated for the airflow.

Another thing is, the J-7's engine tunnel and its diameter is meant to match both the diameter of the engine and its engine requirements. Once that is figured out, you wrap an airframe around it. The JF-17's engine tunnel has to match not just the diameter of the engine, which is much wider, but also is a lot more powerful with the airflow to match, and also not the least, because its a turbofan and not a turbojet which requires even more air for the bypass.

Let's abandon this particular line of discussion.

I do not wish to start a comparison thread here but no, they are not. The Tejas have some major problems to solve relating to AoA, pulling high g maneuvers, its massive overweight problem, etc.

That's all because of a low powered engine which in turn results in maneuverability issues. This will be solved in the batch succeeding the first 40 units. Besides, for the second batch it's does NOT have to choose new avionics, which I believe have not been chosen for the the FC-1 yet.

[crobato]

Whoever was talking of pure deltas or trapezoids ? (you have a sure propensity to skid off the main topic and start talking something else).

The MAC of a simple delta is simply root length by 2. For a cropped one, the standard MAC equation will still be used, which is a simple integral of a function of the co-ord of the wing's edge. This is independent of any sweep or hypotenuse or whatever.

Now answer this : Do you see the sweep variable in ANY equation of aspect ratio presented by you or me so far ? It means that it is independent of the aspect ratio and given an aspect ratio, you can have other sweeps : delta (cropped or not) or non-delta (like Fulcrums). Then you'll understand the folly of your logic.

No that's wrong. Computing for aspect ratio depends on the chord of the wing. For a delta its root length /2 div by wingspan. You're assuming using the square area against the wing span. There are many ways to computer aspect ratio and it depends on the type of wing.

We use deltas here because deltas and variations thereof, are the most common types dues to the superior rigidity and stress loading over any other wing.

With a delta, the sweep becomes a function of the wing span and the wing chord.

Wing span also determines flight behavior.

I contend : Not only the cropped delta wing with flaperon, even the cropped delta alone is visible only in the F-16. No other 4th or 4.5 G fighter aircraft has a cropped delta wing. The JF-17 has virtually copied all of it + I recon even the flaperon configuration.

A cropped delta is simply a clipped delta. Lavi has it, so does the F-CK-1. It simply a functional variation of the delta. The Typhoon and Rafale are other examples.

If you want a tailed delta, put wingtip rails on the wings, more or less the outcome will be the same.

In truth the FC-1 is likely to have more sweep angle on the wing than the F-16, for reasons on its own, partly to improve its top speed due to having lower engine power.

The flight regime is not just decided by speed and altitude which you mistakenly claimed earlier, but by the size of the aircraft and loads carried primarily. All aircraft from FC-1 to J-11 don't fly at top speeds and top g's all the time but they do have similar speeds at which they'll fly most of their missions. Since they weigh differently and carry varying loads, they have to be designed differently.

That's plain wrong. The flight regime is determined before hand in the concept stage of the plane, and then the design is maximized around it. The JF-17 is mainly a low to med altitude aircraft with air combat focused on the subsonic because that's how the customer wants it. The J-8II is a high altitude supersonic aircraft interceptor because that's how the doctrine demands it.

You're assuming that performance is accidental because of loads and what not. Even what a plane is specified in loading is based on intention and design.

[Indianfighter]

No that's wrong. Computing for aspect ratio depends on the chord of the wing. For a delta its root length /2 div by wingspan. You're assuming using the square area against the wing span. There are many ways to computer aspect ratio and it depends on the type of wing.

No. There is just one generalized way which I mentioned, and that is a simple integral over the edge which gives MAC. It's just simplified in case of pure deltas (can't understand why you bring them into picture when we're talking of JF-17..).

With a delta, the sweep becomes a function of the wing span and the wing chord.

No, because for a fixed span and area, you can have many sweeps even trailing edge sweeps. You're just assuming the hypotenuse of cropped deltas (even that is variable for a fixed span and area). You didn't even consider a possible sweep of the trailing edge (as in Fulcrums or F-18).

I maintain : It is no co-incidence that the wing design of JF-17 is a straight copy of the F-16. PAF is a major user of the F-16 too, and it would have surely provided CAC with it's aerodynamic layout.

I go a step further : If you observe, the cropped delta is found ONLY on F-16s and it's clones. If the JF-17 has it, then I conjecture that it must surely be an inspiration from live examples from the PAF's inventory.

This is a matter of interest but you and some Pakistanis here are taking it as an insult. Just imagine : the JF-17 has the distinction of being the first hybrid of a Russian and US fighter, all of it Made in China ! It is of interest to any enthusiast of fighter planes.

A cropped delta is simply a clipped delta. Lavi has it, so does the F-CK-1.

And both these are either F-16 clones or reportedly inspired by the F-16. We can also add the JF-17 to that list now.

The F-CK-1 also has flaperons (courtesy Lockheed). Please take 2 mins to google and look at the JF-17's wings from top view and compare them with F-16. Atleast the leading edge flaperons on both of them are matched but I can't say anything about the trailing edge ones.

That's plain wrong. The flight regime is determined before hand in the concept stage of the plane, and then the design is maximized around it. The JF-17 is mainly a low to med altitude aircraft with air combat focused on the subsonic because that's how the customer wants it.
You're assuming that performance is accidental because of loads and what not. Even what a plane is specified in loading is based on intention and design.

Let's agree to disagree on this, and halt.

[Baibar of Jalat]

All the discussions have revealed the JF 17 has very little in common with F7 or mig 21. More in common with F 16.

Indian fighter thanks for clarifying that, before you were arguing it was the last version on F-7.

(Indianfighter) go a step further : If you observe, the cropped delta is found ONLY on F-16s and it's clones. If the JF-17 has it, then I conjecture that it must surely be an inspiration from live examples from the PAF's inventory.

Well duh, JF 17, uses and influenced by existing designs thats how it is relatively cheap. Only thing that irks me is some people continuing to say it is not a fourth generation design. If China and Pakistan had the F22 budget then maybe something unique would be made.

[FriedRiceNSpice]

That's all because of a low powered engine which in turn results in maneuverability issues. This will be solved in the batch succeeding the first 40 units. Besides, for the second batch it's does NOT have to choose new avionics, which I believe have not been chosen for the the FC-1 yet.

Can you enlighten on us what engine will be used in the future batch?

Saying the JF-17 is a Mig-21/F-16 hybrid is like saying the LCA is a Mirage-2000 with a slightly altered wing shape, or Su-27 is simply an enlarged Mig-29.

Just imagine : the JF-17 has the distinction of being the first hybrid of a Russian and US fighter, all of it Made in China !

What if someone tried to tell you the LCA has the distinction of having the longest development period of any 4th generation aircraft? Surely an honor, right?

And both these are either F-16 clones or reportedly inspired by the F-16. We can also add the JF-17 to that list now.

Inspired, possibly, copied, no. In EVERY aircraft project, the development stage consists of taking a look at what works and starting from there. If using the general dimensions of the F-16 wing provides the best overall flight and handling characteristics, why would you use something different? I assure you that Dassault does not start by looking at clipped deltas or trapezoidal wing designs each time they decide to design a new fighter, they stick with what works. With any aircraft, wing design will always be optimized for that aircraft's specific mission profile and performance characteristics. I assure you that even if they used the F-16's wing as a reference, they no doubt tested thousands of permutations for aspect ratio before finally settling for something that provided the best performance.

[crobato]

No. There is just one generalized way which I mentioned, and that is a simple integral over the edge which gives MAC. It's just simplified in case of pure deltas (can't understand why you bring them into picture when we're talking of JF-17..).

Because the JF-17 uses a clipped delta. Because the rear edge of the triangle is perpendicular and constant to the axis of the plane, the reduction of chord is constant.

Go compute triangles. The moment the wing span is reduced without changing the chord, the sweep increases.

No, because for a fixed span and area, you can have many sweeps even trailing edge sweeps. You're just assuming the hypotenuse of cropped deltas (even that is variable for a fixed span and area). You didn't even consider a possible sweep of the trailing edge (as in Fulcrums or F-18).

I'm strictly talking about a delta. You cannot have many sweeps with a delta because the sweep is a function of the wing span. Anyone who knows geometry can tell that. Go past high school.

Why would you want to vary the wing---I already told you that the delta wing and its variations thereof, provide superior structural rigidity than any other type of wing.

Furthermore, you cannot have many sweeps based on the flight regime. You can't see past the direct correlation of wing sweep to flight regime. An aircraft that must fly faster must have greater sweep, while a plane that must spend more time at lower speeds must have less sweep. L/D ratios and Reynolds Numbers are directly affected by sweep. Furthermore at high speed, there is something called trailing wave drag, and as speed goes higher, the wave front proportionally falls back further, until a certain speed it would hit the wings and create turbulence. The sweep of the wing must prevent that.

I maintain : It is no co-incidence that the wing design of JF-17 is a straight copy of the F-16. PAF is a major user of the F-16 too, and it would have surely provided CAC with it's aerodynamic layout.

I'm sorry, but your conclusion is an insult to aircraft designers everywhere. Just shows you think like an amateur and a fan boy.

Even a wing that resembles like the F-16 is precisely calculated to match the expected flight regime of the aircraft. Just because it may look similar to the naked eye doesn't mean that the geometries are the same. The very number of the geometries count because they directly affect the Reynolds numbers and lift/drag ratios of the wing.

I go a step further : If you observe, the cropped delta is found ONLY on F-16s and it's clones. If the JF-17 has it, then I conjecture that it must surely be an inspiration from live examples from the PAF's inventory.

I'm sorry but what? The F-15's delta can be considered a semi-cropped delta. The Su-27 and the MiG-29 is a hybrid between sweep wing and cropped delta. Cropped deltas are found in the Typhoon, Rafale and Grippen.

This is a matter of interest but you and some Pakistanis here are taking it as an insult. Just imagine : the JF-17 has the distinction of being the first hybrid of a Russian and US fighter, all of it Made in China ! It is of interest to any enthusiast of fighter planes.

Bull. You have no inkling how aircraft is designed. Just because it is Pakistani and Chinese, you go on into that nonsense being J-7 derived. Only an idiot on aircraft affairs thinks you can frankenstein different attributes of different aircraft into one, without examining that how an aircraft is designed to the very last bolt and nut is precisely calculated and intentional to produce the desired result.

If an aircraft is operate on the same flight regimes as the F-16, as in trying to obtain the best performance in the same altitudes and speeds the F-16 operates, you would reach to the same mathematical conclusions on aspect ratio and wing sweep.

An aircraft is like a watch. Just because the mechanisms and gears might look alike doesn't mean the gears are taken from one watch to work on the other. Everything inside a watch is precisely and mathematically calculated to the exact dimensions needed.

And both these are either F-16 clones or reportedly inspired by the F-16. We can also add the JF-17 to that list now.

Yet each of these aircraft has differing geometries from the F-16's.

The F-CK-1 also has flaperons (courtesy Lockheed). Please take 2 mins to google and look at the JF-17's wings from top view and compare them with F-16. Atleast the leading edge flaperons on both of them are matched but I can't say anything about the trailing edge ones.

I;m sorry, but all flaperons look alike. Their exact dimensions though, are different and that's where the math is invested.

Let's agree to disagree on this, and halt.

You don't even has a grasp in understanding what a flight regime is.

You don't understand that a plane's design directly caters to its intended flight and mission regimes.

High aspect ratio favors efficiency at low speed.
Low aspect ratio favors high speed.
Low sweep favors low speed.
High sweep favors high sweep.

If you have an understanding of this you understand why an F-14 or Tornado uses variable sweep wings.

If you look at the plane alone by its wing design, you can get an idea what the flight regimes of the aircraft is, or its flight characteristic.

The F-18 is an example of an aircraft with low sweep and high aspect ratios. Guess what, that sort of wing makes the plane easier to control at low speeds and therefore with carrier takeoffs and landings. It also enables the plane to efficiently loiter around carrier groups at low speed. But at the same time, it makes the plane slow and less efficient at higher speeds, and this is consistent to the criticisms of the aircraft when compared to the F-14 which can sweep back its wings to perform at higher speed regimes. You can figure out from here why an F-15 or an F-16 isn't suited for carrier operations without a major wing design.

I still laugh at your attempt to connect the J-7's intake, when you don't even know WTF how it even works (guess what the Mirage III's intake is closer to how it operates than the first JF-17). Or your attempt to connect a J-7 heritage to the JF-17 without even wondering that a semimonoque design means the aircraft is built around an engine. If the engine has a significantly different size from the original engine, the airframe is practically useless, and the RD-93 is of both significant size and weight compared to the WP-13, which means the airframe, structural design down to the engine intake tunnel, has to be catered and built around the RD-93.

This is not a question of opinion. When there are matters of technology, its a question of right vs. wrong, enlightened or ignorant.

Even if the PAF air marshall says they want to consider using the M88 on the JF-17, the guy doesn't know what he's talking about literally, even if he is an Air Marshall. You cannot change engines just like that without redesigning the airframe structure and intake tunnel and spend another three to five years in the development plan.

You can choose to be ignorant for all I care, just like your previous attempts on JF-17's FCS and the delta canard's lever movement and pitch authority.

[Indianfighter]

All the discussions have revealed the JF 17 has very little in common with F7 or mig 21. More in common with F 16.

Indian fighter thanks for clarifying that, before you were arguing it was the last version on F-7.

Incorrect. I said the FC-1 is a descendant of the J - 7 line. You (and crobato) construed this as a "version".

Besides that, I think the FC-1 does have it's side fuselage and the distinctive canopy shape.

Can you enlighten on us what engine will be used in the future batch?

For LCA it is either Eurojet or GE-414. In case of FC-1 no formal announcement made yet. The PAF chief simply said that the performance of the RD-93 is unsatisfactory and he was possibly evaluating some western engine. No mention of WS-13 either.

What if someone tried to tell you the LCA has the distinction of having the longest development period of any 4th generation aircraft? Surely an honor, right?

Not an issue at all, if the end product rivals the best in Asian fighters. All it needs is a new engine to reach it's max g limit and top speed.

I assure you that even if they used the F-16's wing as a reference, they no doubt tested thousands of permutations for aspect ratio before finally settling for something that provided the best performance.

Yes, they would have and I don't contest that. I'm just saying that it has adopted the F-16's wings almost completely.

Because the JF-17 uses a clipped delta. Because the rear edge of the triangle is perpendicular and constant to the axis of the plane, the reduction of chord is constant.

For a clipped delta, the simplified formula which you gave is not applicable. That's only for a simple delta . I don't understand why you are repeatedly discussing pure deltas, when FC-1 has a cropped or a clipped one. The MAC for FC-1's wing would be found out by the general formula I gave -- and which is not a function of sweep at all.

Go compute triangles. The moment the wing span is reduced without changing the chord, the sweep increases.

Look aspect ratio keeps span and area into picture and NOT sweep. Your contention that the FC-1 and F-16 happen to have similar wings is not a co-incidence is not true at all.

I'm strictly talking about a delta. You cannot have many sweeps with a delta because the sweep is a function of the wing span. Anyone who knows geometry can tell that. Go past high school.

And you first go pass elementary school. "Many" is still more than one, and the aspect ratio is sweep independent (see the a.r. equation). So the JF-17 could have had wings other than say a cropped delta, and pure delta. It could've had a slightly trapezoid one (like F-18) or even F-15 style trailing double sweep or even a different single sweep. But it didn't, and adopted the F-16's wing.

Why would you want to vary the wing---I already told you that the delta wing and its variations thereof, provide superior structural rigidity than any other type of wing.

So ? J-10, Gripen, LCA, F-CK-1, Rafale all have pure or cropped deltas. The point here is that a) all of them are fairly distinguishable from each other and b) only F-16 and it's clones like F-CK-1 have the special variation i.e. cropped delta (one which not only stores a wing tip missile, but also does not extend upto the begin of the exhaust) . It can't be a mere co-incidence that JF-17 also happens to have a cropped delta that is visually indistinguishable from the F-16.

It is an interesting nugget of info that the JF-17 was initially called F-17; the J was added later to signify "joint". The F-17 was supposed to signify a new step after the PAF's existing F-16.

If an aircraft is operate on the same flight regimes as the F-16, as in trying to obtain the best performance in the same altitudes and speeds the F-16 operates, you would reach to the same mathematical conclusions on aspect ratio and wing sweep.

Answer this first : An LCA has more or less the same flight regime as the JF-17 (I'm assuming your definition). The intended operating speeds, operating g-limits and loads carried are meant to be similar. Yet, do their designs match ?

On top of that a JF-17 does NOT carry the F-16's loads and does not weigh as much and still a lot of it's "flight regime" (per your own definition) may well overlap with the F-16. Even their fuselage shapes are different. Your efforts to justify the wing shapes of an F-16 with JF-17 by claiming they have the same flight regimes is thus futile, because they don't.

I;m sorry, but all flaperons look alike. Their exact dimensions though, are different and that's where the math is invested.

The point is that leading edge flaperons are a creation present only on the F-16 and it's clones. They also certainly appear on the JF-17. About trailing edge flaperons that don't act as airelons, I can't say.

The F-18 is an example of an aircraft with low sweep and high aspect ratios. Guess what, that sort of wing makes the plane easier to control at low speeds and therefore with carrier takeoffs and landings. It also enables the plane to efficiently loiter around carrier groups at low speed. But at the same time, it makes the plane slow and less efficient at higher speeds, and this is consistent to the criticisms of the aircraft

OK. Then why didn't Boeing redesign the F-18's wing's for it's land version ? After all, like the Royal Australian Air Force which has the F-18, it's the IAF that is evaluating the F-18 SH and not the IN.

Even for LCA's naval variant, what has been changed is the nose and undercarriage : the wing has remained unchanged except for a leading edge levcon.

Even if the PAF air marshall says they want to consider using the M88 on the JF-17, the guy doesn't know what he's talking about literally, even if he is an Air Marshall. You cannot change engines just like that without redesigning the airframe structure and intake tunnel and spend another three to five years in the development plan.

He didn't specifically mention M-88 or any other engine. An intake and fuselage redesign is obviously implied in such cases (it's not a keyboard you're attaching to a home computer). That's what will be done when LCA will be fitted with either eurojet or GE-414.

You can choose to be ignorant for all I care, just like your previous attempts on JF-17's FCS and the delta canard's lever movement and pitch authority.

I think you were the one blissfully unaware of your ignorance.

[crobato]

Incorrect. I said the FC-1 is a descendant of the J - 7 line. You (and crobato) construed this as a "version".

Besides that, I think the FC-1 does have it's side fuselage and the distinctive canopy shape.

Excuse me? I guess you really never saw the JF-17 canopy and compare it to the J-7's canopy do you?

Side fuselage? That's a completely idiotic thing to say, considering their diameters are completely different. Just because the plane has a structural spine?

Whose fuselage looks similar to the MiG-21 family? Why go check the Delta Dagger, Delta Dart and the Mirage III family for that matter. They're all semi-monoque designs. By this I mean a structural design that essentially appears like a tube surrounding an engine that is reinforced by an upper spine. In a pure monoque design, the structure is held by the strength of the tube itself.

For a clipped delta, the simplified formula which you gave is not applicable. That's only for a simple delta . I don't understand why you are repeatedly discussing pure deltas, when FC-1 has a cropped or a clipped one. The MAC for FC-1's wing would be found out by the general formula I gave -- and which is not a function of sweep at all.

What a joke. Even your formula is incorrrect.

Its the square of wing span / wing area.

Furthermore, this is just one of different formulas.

Look aspect ratio keeps span and area into picture and NOT sweep. Your contention that the FC-1 and F-16 happen to have similar wings is not a co-incidence is not true at all.

BS. Both will have similar flight regime requirements (combat altitude and most common speed of engagement), then with variations in sweep and aspect ratio for specific, particular requirements and design traits. The JF-17 cannot afford/have the sweep you see on the F-16 if it is to attain the same speed as the F-16 because the JF-17 has less power.

And you first go pass elementary school. "Many" is still more than one, and the aspect ratio is sweep independent (see the a.r. equation). So the JF-17 could have had wings other than say a cropped delta, and pure delta. It could've had a slightly trapezoid one (like F-18) or even F-15 style trailing double sweep or even a different single sweep. But it didn't, and adopted the F-16's wing.

Shows your complete BS.

http://en.wikipedia.org/wiki/Talk:Aspect_ratio_(wing)

In aviation, the aspect ratio of aircraft tapered wings is found by dividing the square of the wing span {b} by the total wing area (S):

AR = b2/S

If the wing has a constant chord, the aspect ratio is the result of dividing the wingspan (b) by the value of the chord (c):

AR = b/c

Similarly, if the value of the mean geometric chord is known, the aspect ratio is the result of dividing the wingspan by the value of the mean geometric chord:

AR = b/cmean."



Now you know what wing chord is? If wing span is the width, chord would be the length. For a clipped delta, to get the average chord, you get the chord of the shortest length, which is the point before the wing tip, add it to the longest chord, which is around the wing root, then divide by two. For a pure delta, you simply just get the length of the wing root, which is the longest wing chord, divided it by two.

Now you continue to ignore my argument that a deltoid provides the greatest simplicity of construction and the highest load transfers per weight. You want to make a cheap fighter with high G rating and payload, go with this approach.

You don't have or choose to have to complex geometry wings because structurally, they're bad ideas. The simpler the wing design is, the stronger it is.

So ? J-10, Gripen, LCA, F-CK-1, Rafale all have pure or cropped deltas. The point here is that a) all of them are fairly distinguishable from each other and b) only F-16 and it's clones like F-CK-1 have the special variation i.e. cropped delta (one which not only stores a wing tip missile, but also does not extend upto the begin of the exhaust) . It can't be a mere co-incidence that JF-17 also happens to have a cropped delta that is visually indistinguishable from the F-16.

More BS from you. The J-10 and Gripen are not exactly very distinguishable from each other above. Actually the planform of the J-10 is more similar to the Gripen's than the Lavi. Lavi's own flight regimes are deeply rooted in the IAF's experience with the Mirage III and A-4 Skyhawk. In fact, the J-10's aspect variance from the Lavi shows the PLAAF has different missions in mind, at different altitude and speed regimens, than the Israeli Air Force.

The Rafale and the Typhoon also has a similar planform with each other.

Planform of the LCA is similar to the Viggen and the F-16XL

I'm sorry to say but the JF-17 does have a greater sweep than the F-16. Convenient and inconsiderate for you to consider that LERX plays a fundamental aspect in the main wing design and yet you choose to disregard that completely.

LERX vortices will flow over the wing and there fore it will affect the wing. You cannot extend the rear edge of the wing past the point where the vortices would undergo disintergration, causing turbulence on the wing. The longer wing chord of the JF-17 becomes allowable if vortice lamination is held longer, and that depends a lot on the geometry of the wing LERX. The corner of the LERX with the wing is the point where the vortice would generate. Its more outbound on the JF-17 due to the convex form compared to the concave form of the LERX in the F-16.

It is an interesting nugget of info that the JF-17 was initially called F-17; the J was added later to signify "joint". The F-17 was supposed to signify a new step after the PAF's existing F-16.

That's BS. It was from the very beginning, FC-1. The 17 is of course. to make it sound after the F-16.

Answer this first : An LCA has more or less the same flight regime as the JF-17 (I'm assuming your definition). The intended operating speeds, operating g-limits and loads carried are meant to be similar. Yet, do their designs match ?

I'm not sure and I don't think if the LCA has the same flight regime as the JF-17. By far, most low aspect delta wing designs were and still originally meant for high speed interception, including the MiG-21 and Mirage III.

Please note why all airliners have the same kind of wings.

On top of that a JF-17 does NOT carry the F-16's loads and does not weigh as much and still a lot of it's "flight regime" (per your own definition) may well overlap with the F-16. Even their fuselage shapes are different. Your efforts to justify the wing shapes of an F-16 with JF-17 by claiming they have the same flight regimes is thus futile, because they don't.

Your ignorance. Loads have nothing to do with flight regime. I'm talking about optimizing for a certain band of altitude and speed range. Fuselage shapes have nothing to do with flight regime, another ignorant statement from you.

The point is that leading edge flaperons are a creation present only on the F-16 and it's clones. They also certainly appear on the JF-17. About trailing edge flaperons that don't act as airelons, I can't say.

Again, pure ignorance of background in flaperons.

Flaperon - Wikipedia, the free encyclopedia

You see them from private aircraft to Ospreys.

Somehow you're saying that its exclusive to the F-16 strikes me as enormously strange. Even stranger is to refer flaperons on the leading edge. On the leading edge you got slats. Flaperons are only in the back.

Many planes have leading edge slats. The Me-109 from WWII has them. The MiG-21 doesn't have them---only the J-7E in the Fishbed family has leading edge slats.

What's the point of having a flaperon? Why for the sake of simplicity and reducing both weight and cost, a common theme for budget fighters like the JF-17 and the early F-16.

OK. Then why didn't Boeing redesign the F-18's wing's for it's land version ? After all, like the Royal Australian Air Force which has the F-18, it's the IAF that is evaluating the F-18 SH and not the IN.

Because the cost and testing for a new wing variant is astronomical. For that matter, all land based Hornets will fly and perform much like the naval ones, both their good points and bad points (the latter actually puts the F-18 in a disadvantage against "faster" jets like the F-16 and F-15). Let me point out to you that the SH did not fundamentally differ the old Hornet in terms of aspect ratio.

Even for LCA's naval variant, what has been changed is the nose and undercarriage : the wing has remained unchanged except for a leading edge levcon.

Until it actually works I would probably say not a good idea.

When the YF-17 went to the F-18 naval version, yes the wing was redesigned.

On the Su-33, and the wing was also redesigned. It has a longer wing span and higher aspect ratio. The wing chord is actually decreased with the shortening of the wing root, which also provided space to put the canard on front. Note, the front sweep of the Su-27 and its LERX is actually similar to the F-16's.

He didn't specifically mention M-88 or any other engine. An intake and fuselage redesign is obviously implied in such cases (it's not a keyboard you're attaching to a home computer). That's what will be done when LCA will be fitted with either eurojet or GE-414.

A good reason why this fighter is a perennial no show. Keep designing a fighter around different engines, and it won't leave the drawing board.

I think you were the one blissfully unaware of your ignorance.

The only clearly ignorant to anyone here is one who suggests a family resemblance to another plane due to the shape of the canopy.

Maybe we can use that as the reason why the J-10 is not related to the Lavi, can we?

[mean_bird]

I maintain : It is no co-incidence that the wing design of JF-17 is a straight copy of the F-16. PAF is a major user of the F-16 too, and it would have surely provided CAC with it's aerodynamic layout.

That's a very naïve statement.

You cannot just copy another planes wings and hope it will be optimized for your aircraft or even be flyable. Aerodynamics have been studied for like a century now, and a lot of designs are pretty much documented and available for all.

As I said earlier, PAF was pretty impressed (or used to or it suited their needs, whatever you call it) by the handling of F-16 and its flight regime. Thus they took a similar wing design, but ofcourse they had to adopt it to suit the JF-17. Moreover, they also needed other characteristics of the design, which can be seen e.g. LERX.

You must realize that it is rather impossible to copy some aerodynamic features straight out from one plane into another and hope it will work. I am talking in the literal sense of the meaning not just because "Oh, copy is not a politically correct word or insulting" or something else. You simply cant do it.

The JF-17 is very unique in the sense that its specifically tailored to PAF needs, right to the very last details.

This is a matter of interest but you and some Pakistanis here are taking it as an insult. Just imagine : the JF-17 has the distinction of being the first hybrid of a Russian and US fighter, all of it Made in China ! It is of interest to any enthusiast of fighter planes.

I am afraid reality doesn't work on imagination.

And Russia has more than one plane. Ever wondered why Mikoyan were the technical consultants? Because they have experience with a single-engine M-R fighter that used the RD-33 engine. EADS would be providing consultancy if the LCA decides to go for european engine, that that would also be for the reason mentioned above.

Even if the PAF air marshall says they want to consider using the M88 on the JF-17, the guy doesn't know what he's talking about literally, even if he is an Air Marshall. You cannot change engines just like that without redesigning the airframe structure and intake tunnel and spend another three to five years in the development plan.

PAF officials have mentioned going for western engines because they are more maintenance friendly, but I have never heard any official statement saying it will be the M88.

There's are atleast 200 more JF-17s to be built after the first 50 plus export orders could also be there in the longer run. We could very well be talking about a new engine or variant specifically for the JF-17, whose integration would be no different than say a WS-13.

Answer this first : An LCA has more or less the same flight regime as the JF-17 (I'm assuming your definition). The intended operating speeds, operating g-limits and loads carried are meant to be similar. Yet, do their designs match ?

Really? I don't think the above statement is true.

On top of that a JF-17 does NOT carry the F-16's loads and does not weigh as much and still a lot of it's "flight regime" (per your own definition) may well overlap with the F-16. Even their fuselage shapes are different. Your efforts to justify the wing shapes of an F-16 with JF-17 by claiming they have the same flight regimes is thus futile, because they don't.

Flight regime is not about loads. Its about in characteristics....like optimized for low or high speeds, lower or higher altitudes, etc.

[Baibar of Jalat]

Incorrect. I said the FC-1 is a descendant of the J - 7 line. You (and crobato) construed this as a "version".

Besides that, I think the FC-1 does have it's side fuselage and the distinctive canopy shape.

Already highlighted by Crobato

If you look at the various versions of mig 21 and J7, you will see many changes in the canopy. What does the picture show you (in sinodefence link), the Chinese built a range of canopy's. As your picture of Egyptian? J-7 and FC 1 suggests the Chinese had developed a canopy that they were proud off. If isn't broke, why fix it.

Jian-7 (J-7, F-7, Fishbed) Interceptor Fighter - SinoDefence.com

Mig-21 Fishbed

[Indianfighter]

Excuse me? I guess you really never saw the JF-17 canopy and compare it to the J-7's canopy do you?

Side fuselage? That's a completely idiotic thing to say, considering their diameters are completely different. Just because the plane has a structural spine?

Do you understand similarity ? I've already told you that the exact diameters are not even in discussion : it's their shapes. Their SIMILAR shapes.

Whose fuselage looks similar to the MiG-21 family? Why go check the Delta Dagger, Delta Dart and the Mirage III family for that matter. They're all semi-monoque designs. By this I mean a structural design that essentially appears like a tube surrounding an engine that is reinforced by an upper spine. In a pure monoque design, the structure is held by the strength of the tube itself.

You're talking the procedure of making them and so trying to say that because the procedure is the same, they all happen to look similar.

What a joke.

Its the square of wing span / wing area.

Furthermore, this is just one of different formulas.

You understood that now ? I have been repeating that formula since the past n posts and even provided the generalized integral that goes into calculating the MAC, which goes into calculating the span component of the formula.

BS. Both will have similar flight regime requirements (combat altitude and most common speed of engagement), then with variations in sweep and aspect ratio for specific, particular requirements and design traits. The JF-17 cannot afford/have the sweep you see on the F-16 if it is to attain the same speed as the F-16 because the JF-17 has less power.

It has less power because it weighs less and carries lesser loads. That means that it has to have different design considerations; yet it's wing has an uncanny resemblance to the F-16's.

Shows your complete BS.

http://en.wikipedia.org/wiki/Talk:Aspect_ratio_(wing)

In aviation, the aspect ratio of aircraft tapered wings is found by dividing the square of the wing span {b} by the total wing area (S):

AR = b2/S

If the wing has a constant chord, the aspect ratio is the result of dividing the wingspan (b) by the value of the chord (c):

AR = b/c

Similarly, if the value of the mean geometric chord is known, the aspect ratio is the result of dividing the wingspan by the value of the mean geometric chord:

AR = b/cmean."

And that mean aerodynamic chord MAC is calculated by a simple integral of the square of the wing's leading edge co-ordinates from root to tip. This is a generalized formula (if you are even aware what that is). It will also give you the simplified results that you have just discovered, in the most simplistic cases like a pure delta or a cropped one.

Now you know what wing chord is? If wing span is the width, chord would be the length. For a clipped delta, to get the average chord, you get the chord of the shortest length, which is the point before the wing tip, add it to the longest chord, which is around the wing root, then divide by two. For a pure delta, you simply just get the length of the wing root, which is the longest wing chord, divided it by two.

How many times do I have to repeat that the generalized formula given will ALSO yield the same MAC ? It will work for ANY wing and not just pure deltas or cropped deltas. And it is sweep independent ?

More BS from you. The J-10 and Gripen are not exactly very distinguishable from each other above. Actually the planform of the J-10 is more similar to the Gripen's than the Lavi. Lavi's own flight regimes are deeply rooted in the IAF's experience with the Mirage III and A-4 Skyhawk. In fact, the J-10's aspect variance from the Lavi shows the PLAAF has different missions in mind, at different altitude and speed regimens, than the Israeli Air Force.

Now why discuss Lavi and Mirages ? J-10 is much bigger and heavier than Lavi and hence doesn't have the same flight regime. It only looks similar.

Planform of the LCA is similar to the Viggen and the F-16XL

Viggen ?

I'm sorry to say but the JF-17 does have a greater sweep than the F-16. Convenient and inconsiderate for you to consider that LERX plays a fundamental aspect in the main wing design and yet you choose to disregard that completely.

A cropped delta of the type of F-16 does not extend to the start of the exhaust and a provision for wing-tip missile. This type of cropped delta is NOT found on any other fighter aircraft other than F-16 and clones. Now, it is also found on the JF-17 which is proof enough that F-16's from PAF have been used for the purpose.

The sweep is also nearly the same if you try to superimpose the images of their wings.

I said I appreciate Lerxs and DSI on the FC-1 if it helps it fly well. I just made an observation that it's wings are uncannily similar to the F-16.

Even Pakistanis like mean_bird have accepted that it's wings are like F-16. He rightly said that lots of computations go into even for doing that, and I agreed.

Again, pure ignorance of background in flaperons.

Flaperon - Wikipedia, the free encyclopedia

You see them from private aircraft to Ospreys.

Somehow you're saying that its exclusive to the F-16 strikes me as enormously strange. Even stranger is to refer flaperons on the leading edge. On the leading edge you got slats.

On fighter aircraft flaperons are only on F-16s -- never have been anywhere else. I agree the they should be slats on the leading edge, but Wikipedia's page on F-16 refers them as flaperons.

A good reason why this fighter is a perennial no show. Keep designing a fighter around different engines, and it won't leave the drawing board.

Well, the JF-17 is also going that way now. No sign of WS-13 and now PAF wants an altogether new western engine.

As I said earlier, PAF was pretty impressed (or used to or it suited their needs, whatever you call it) by the handling of F-16 and its flight regime. Thus they took a similar wing design, but ofcourse they had to adopt it to suit the JF-17.

Good, you atleast agreed with me on one point. I've already said that they surely must have had to do computations to adopt it on the JF-17 + adding lerxes and dsi.

PAF officials have mentioned going for western engines because they are more maintenance friendly, but I have never heard any official statement saying it will be the M88.

Me neither. crobato said that thing about M-88.

[FriedRiceNSpice]

Me neither. crobato said that thing about M-88.

Which is why he quoted Crobato...

Viggen ?

Yes Viggen, as in the 4th generation fighter built by Saab that was replaced by the Gripen. I'd imagine that the Viggen and LCA would be quite similar in performance/maneuverability. Granted that the LCA gets some new engines.