Can Israel develop its own stealth fighter jet

[fltworthy]

Ahh ever heard of the J-9? Paying attention are you?

Yes, I am familiar with the history of the J-9. I am also aware that its arrangement of intakes, and even its wing-and-canard arrangement (the J-9 never featured the kind of all-moving canard seen on either the J-10 or Lavi for example) were entirely different.

If you want to discuss facts, please learn to be civil and not insulting. If not, you can expect the same in return.

J-7 (MiG-21) – J-9 – J-10. The design history is quite clear, announced by the Chinese and obvious to anyone with an aero structure engineering eye.

One of us has a master of science in aerospace engineering and over two decades of hands-on experience in the business. The other doesn't. Do you really need me to tell you which one is which?

 

[fltworthy]

Total BS. Zakheim never proposed these aircraft but Northrop and McAir in consultation with the IDF as part of various force structure mixes.

The IDF had already rejected the F-20 as a contendor for future purchases. Zakheim practically had to beg Northrop to propose the airplane again - as a Lavi "alternative". No one in the IDF ever requested a cost quote on that airplane as a "alternative" to the Lavi, nor the AV-8B.

 

[Abraham Gubler]

One of us has a master of science in aerospace engineering and over two decades of hands-on experience in the business. The other doesn't. Do you really need me to tell you which one is which?

LOL. Well there is no evidence tendered that you are any good at your job. So come address the issues rather than point at your degree hanging on the wall. You’ve made a bollox job trying to address the design issues and you’ve defamed Zakheim or are ignorant of his work.

This issue will not be determined by calculating skin stress under certain flight conditions. It is determined by careful collation of facts, assessment of merit, analytical inquiry and logical determination. That is my degree, that is my two decades of experience.

Without even getting visual lets compare shall we:

Length: 47 ft 10 in - 50 ft 10 in
Wingspan: 28 ft 10 in - 31 ft 10 in
Height: 15 ft 8 in - 15.7 ft
Wing Area: 355 ft² - 419.8 ft²
Empty Weight: 15,500 lb - 21,495 lb
Loaded Weight: 22,025 lb - 32,797 lb
Engine Max Thrust: 20,600 lbf - 29,101 lbf
Engine Dry Weight: 2,848 lb – 3,454 lb
Range: 2,300 mi - 682 mi
Service ceiling: 50,000 ft - 59,055 ft
Wing loading: 62.0 lb/ft² - 69 lb/ft²

How can those figures be from one plane derived from another?

 

[Abraham Gubler]

The IDF had already rejected the F-20 as a contendor for future purchases. Zakheim practically had to beg Northrop to propose the airplane again - as a Lavi "alternative". No one in the IDF ever requested a cost quote on that airplane as a "alternative" to the Lavi, nor the AV-8B.

And this is a bad thing? Zakheim had a budget to give out contracts to US companies to work out alternate force structures (so it was hardly “begging” despite Northrop’s lack of motivation). It was all about giving the IDF choices. Of course they were going to select either the F-16 or F/A-18 as they were closer to Lavi performance but providing them with more options is not a bad thing.

This is very, very far from some evidence that Zakheim was an amateurish wrecker destroying the IDF with Harriers or Tigersharks. I guess you don’t learn how to make that kind of assessment in aerospace engineering science…

 

[fltworthy]

LOL. Well there is no evidence tendered that you are any good at your job. So come address the issues rather than point at your degree hanging on the wall. You’ve made a bollox job trying to address the design issues and you’ve defamed Zakheim or are ignorant of his work.

This issue will not be determined by calculating skin stress under certain flight conditions. It is determined by careful collation of facts, assessment of merit, analytical inquiry and logical determination. That is my degree, that is my two decades of experience.

LOL. I work with the hardware you only dream about. You have yet to respond to any of the obvious design features that - as I pointed out previously - underline the common lineage between the Lavi and the J-10. Since you seem to have forgotten them, allow me to remind you - and to expand on the details.

Both the J-10 and the Lavi feature a blended-wing design, with area ruling - features not seen on the MiG-21, nor even on the Eurocanards. From your previous reply Gubler, you obviously do not know what area ruling is. Go look it up. It produces the "Coke bottle" look seen on the Lavi, the J-10, and such vintage aircraft as the Buccaneer. It was a popular approach back in the 1960s, aimed at minimizing transonic and supersonic wave drag. It largely fell out of fashion amongst most fighter developers during the 1970s and 80s, as engine thrust grew (allowing more external fuel to be carried) and as the improvement in strike radius was seen as less important than incorporating added electronics. It was revived by IAI when developing the Lavi, for which strike radius was essential. It was carried over when developing the J-10.

Both the J-10 and the Lavi feature a close-coupled canard-delta design - features not seen on the MiG-21, and which both share with such aircraft as the Rafale, Gripen and Kfir (although not with the Eurofighter Typhoon - which features a long-coupled canard-delta design). The Chinese already developed a scaled-up MiG-21 - as the original F-8 design bears witness to (look it up if you don't know what I'm talking about). The PLAAF learned from that experience. A MiG-21 style configuration was only going to carry them so far. The J-10 is anything but that.

Both the J-10 and Lavi feature twin ventral strakes, which increase lateral stability and also protect the engine from tail-strike during over-rotation - features not seen on either the MiG-21 or the Eurocanards. So what do you think led the developers at Chengdu to this arrangement? The MiG-21 experience that you keep alluding to? Please.

Both the J-10 and Lavi feature a single engine with a ventral inlet, another combination not seen on either the MiG-21 or the Eurocanards. This is particularly significant - since the other source of fighter know-how that China tapped into during the early 1990s - Russia - has elected to stay clear of this kind of configuration. The Russians figured out early that a ventral inlet is not well suited to rough field conditions, where it is at heightened risk for ingesting debris on take-off or landing. So what do you think inspired the Chinese to adopt a configuration so alien to either their previous design experience, or the best practices of the Russian developers who assisted on the FC-1/JF-17? Do I really need to spell it out for you?

As I pointed out before, anyone who has studied the arrangement of access panels on the center fuselage fuel tank should have noticed the obvious design similarities between the J-10 and Lavi. This same structural arrangement can also be seen on the F-16 - but will not be found on any of the Eurocanards, and certainly not on the MiG-21 (for which maintenance panels were a distant afterthought). You won't find anything like this on any Russian aircraft, nor any of China's other fighter designs. So what do you think inspired the Chinese to suddenly care about access panels?

Here's another one you probably didn't know. The Lavi wing was redesigned part way through the development effort - to allow the airplane to carry additional payload. The redesign was not as much a question of strengthening the wing - as much as it was a question of adding sufficient control authority to allow the airplane to handle the extra weight. The first two Lavi prototypes flew with the original wing - but starting with the third prototype (which later became the Lavi TD flight test demonstrator), they added an auxiliary elevon. It can be seen inboard and aft of the ventral strakes. You will not find this feature on any of the Eurocanards, and certainly not on the MiG-21. You will find it on the Lavi TD, and you will find it on the J-10. Funny thing.​

I could add that - as it has been pointed out before - China no longer denies Israeli involvement in the development of the J-10. Their own chief test pilot has admitted that he travelled to Israel to train in the Lavi flight simulator prior to his first flight in the J-10. Russian engineers who were visiting the Chengdu site during the early 1990s also reported that there were placards at the site written in Hebrew for the benefit of the on-site Israeli consulting staff. The connection between the two airplanes is well known.

Without even getting visual lets compare shall we:

Length: 47 ft 10 in - 50 ft 10 in
Wingspan: 28 ft 10 in - 31 ft 10 in
Height: 15 ft 8 in - 15.7 ft
Wing Area: 355 ft² - 419.8 ft²
Empty Weight: 15,500 lb - 21,495 lb
Loaded Weight: 22,025 lb - 32,797 lb
Engine Max Thrust: 20,600 lbf - 29,101 lbf
Engine Dry Weight: 2,848 lb – 3,454 lb
Range: 2,300 mi - 682 mi
Service ceiling: 50,000 ft - 59,055 ft
Wing loading: 62.0 lb/ft² - 69 lb/ft²

How can those figures be from one plane derived from another?

So by your line of reasoning, the F/18-E/F couldn't possibly have been derived from the F/A-18C/D - because the dimensions are different? Please.

The design of the J-10 was scaled up from Israel's Lavi experience, to match the size and performance of the larger engine, and to match the range requirements that China was seeking. You probably don't know this, but the Lavi as it was test flown was not the same as the original aircraft that had been proposed by IAI in 1980. The original Lavi proposal - labeled Layout 33 - was built around the much smaller F404 engine, and had targeted an empty weight of 11,110-lb (5,040-kg). When the IDF later revised its requirements - demanding more range, payload, and a more sophistocated avionics suite - the engine was changed to the larger PW1120, and the airplane was scaled up: eventually achieving an empty weight of 15,700-lb (7,120-kg).

The J-10 was similarly scaled up from Israel's experience with building, and flight testing the Lavi. I don't know where you copied your figures from when you quoted your proposed statistics for the J-10. The Chinese government has not yet released any official statistics, and there are quite a few independent estimates floating around the internet and in the aviation press. I am not going to tell you, point by point, which one of your statistics is wrong. I will tell you, however, that the numbers that you are quoting for maximum range are not even in the ballpark. Official numbers quote the maximum strike radius of the Lavi at 1,200 nautical miles (2,220 km), in a hi-lo-hi mission profile. Carrying more fuel and with broadly similar aerodynamic characteristics, even a neophyte should know that the strike radius (much less the range) of the J-10 is not going to be as low 682 miles - not even with a head-wind.

 

[fltworthy]

And this is a bad thing? Zakheim had a budget to give out contracts to US companies to work out alternate force structures

No, Zakheim did not have a budget for awarding contracts to US companies. The Foreign Aid budget was apportioned by the US Congress to support Israel's defense needs, and it was not up to Zakheim or his masters in Weinberger's office as to which US contractors it was awarded to or how it was spent..

This is very, very far from some evidence that Zakheim was an amateurish wrecker destroying the IDF with Harriers or Tigersharks.

Sorry, but after decades in the industry I have a very low opinion of bureaucrats who don't know the first thing about aviation, trying to enforce their decisions on those of us who do. Zakheim was trying to pad his Lavi "alternatives" proposal with aircraft that were clearly unsuitable, in order to make it appear as if there were lots of options floating around out there - when in fact there were very few. It would be more than a decade before Israel took deliver of an evolved F-16 version - the F-16I Soufa - that finally gave them the kind of range and payload that the Lavi had been intended to provide. But then again, it really was never Zakheim's mission to provide the IDF with the best match to their defensive needs. His job - as he freely admits in his book - was to "terminate" the Lavi, nothing else.

 

[gf0012-aust]

A reminder for all and aimed at none.

Stay on the subject and play the ball.

We expect a degree of self moderation to be in play...

 

[Abraham Gubler]

No, Zakheim did not have a budget for awarding contracts to US companies. The Foreign Aid budget was apportioned by the US Congress to support Israel's defense needs, and it was not up to Zakheim or his masters in Weinberger's office as to which US contractors it was awarded to or how it was spent..

The contracts were for the force structure analysis for Lavi alternatives not for the supply of aircraft. I thought I made that perfectly clear. Northrop at that time was overstretched with various RFP submissions to the USG and trying to market the F-20 to actual likely customers.

Sorry, but after decades in the industry I have a very low opinion of bureaucrats who don't know the first thing about aviation, trying to enforce their decisions on those of us who do. Zakheim was trying to pad his Lavi "alternatives" proposal with aircraft that were clearly unsuitable, in order to make it appear as if there were lots of options floating around out there - when in fact there were very few.

Absolutely. I said the same thing a few posts back. But how is this a bad thing? Its certainly a lot further from your initial statements about trying to force the F-20 and AV-8B onto the IDF.

It would be more than a decade before Israel took deliver of an evolved F-16 version - the F-16I Soufa - that finally gave them the kind of range and payload that the Lavi had been intended to provide. But then again, it really was never Zakheim's mission to provide the IDF with the best match to their defensive needs.

Of course. All things I have referred to above. The only contention is the implication that the F-16I was somehow a delay on ISD from the Lavi. The schedule problems of the Lavi were huge at cancellation and likely to get worse, especially if they wanted Israeli built engines.

Now your commentary on Zakheim has moved a lot since your initial slander. In fact it aligns strongly now with mine:

Zakheim never sets out to pass himself of as anything other than the accountant given the job of convincing Israel that the Lavi was against its own economic interest.

His job - as he freely admits in his book - was to "terminate" the Lavi, nothing else.

Its taken a day and two counter responses from yours truly to bring you around from your initial slanderous and inaccurate contentions.

 

[Abraham Gubler]

Let’s get the insults out of the way first.

LOL. I work with the hardware you only dream about.

I’m pretty sure I don’t dream about hardware…

From your previous reply Gubler, you obviously do not know what area ruling is. Go look it up.

I know enough about area ruling to see it on the F-17/18, one of those planes of the 70s and 80s you just said don’t have it… You don’t need to ‘coke bottle’ a fuselage to equalise transonic drag across the length on aircraft.

You have yet to respond to any of the obvious design features that - as I pointed out previously - underline the common lineage between the Lavi and the J-10. Since you seem to have forgotten them, allow me to remind you - and to expand on the details.

I or any other poster is under no obligation to respond sentence by sentence to anything anyone else writes.

But in short you seem to think the following design features:

Blending wing roots into the fuselage (which is NOT a blended wing design – that implies fuselage generated lift)
Area Ruling
Close-coupled canard-delta
Ventral strakes
Single engine
Ventral inlet
Centre fuselage fuel tank

Are exclusive and unique to the relationship between the Lavi and the J-10? Please…

But here lies the crux of the matter. I have constantly maintained that Israel had major input into the J-10 design and build. The key point of contention I have rejected is that the J-10 is a copy of the Lavi. It can’t be they are made of completely different materials and of completely different size. The Hornet – Super Hornet relationship bears no comparison to Lavi-J-10. A fuselage plug and a new wing is very, very different to the entirely different scales of the Lavi-J-10.

What actually happened with the J-10 is that after Glasnost/Perestroika/Tiananmen the Chinese lost access to American/European technology but gained it to Soviet. So suddenly they could brush off the old J-9 with a decent engine. But with their 1950s level industry they were a long way from making this “J-10” anything other than a high thrust MiG-21. The Russians weren’t interested in anything other than selling their existing designs and then along came Israel. Loaded to bear with engineering staff and no longer with the South African project to follow Lavi it was nothing but gold for IAI.

The Israelis could not offer China the opportunity to build a Lavi or even a big Lavi because there is no way the Chinese could build such a composite intense aircraft. But they could provide a range of aerodynamic tweaks to the core J-9 aluminium fuselage and wing. You are mistaking those aerodynamic tweaks as being the centrepiece of the design.

And where do I find out these sorts of things about the Lavi? Having lunch in the IAI restaurant at Lod with Blade engineers is a good starting point. But while that’s part of my waking experience its perhaps still in your dreams…

 

[Feanor]

Guys cut the personal comments. You have an interesting discussion going. Don't ruin it with snide remarks and attacks on character and experience. Your arguments speak for themselves.

 

[Abraham Gubler]

Guys cut the personal comments. You have an interesting discussion going. Don't ruin it with snide remarks and attacks on character and experience. Your arguments speak for themselves.

I’m quite sure we would both like to draw back from the insults. For my side of it I was outraged to see such a vicious personal attack against someone who obviously is not on this forum and unable to defend himself (Zakheim). Blaming the messenger of ill news seems to be a common thread amongst the defence community.

So I apologise to Flight Worthy for calling into question his professional qualifications – in a way which to me seemed more like a satirical questioning – and hope we can continue in a less charged vein.

Which brings me to this point: the wings. I’m sure all of us would agree that the wings of an aircraft are pretty much the most important feature. No wings, no plane. So if the J-10 is a scaled up Lavi one would expect some wing similarity?

So what kind of wing does a Lavi have? A swept back multi spar wing made of graphite epoxy. Some 14 spars by my count with three longitudal stiffeners.

So what about the J-10? A right angles three spar, five longitudal stiffener wing made of aluminium. Very similar to the J-8/J-9 wing but simplified thanks to the removal of the undercarriage to the fuselage and subsequent redundancy of the leading edge tanks (removed in the J-8 anyway). The Israelis have obviously convinced the Chinese to add a leading edge flap as in the Lavi which gives the wings a strong external similarity

I for one can’t reconcile the two designs. They are about as different as two deltas can be.

And on the other topic of area ruling a fuselage perhaps a good look at the Chinese J-8 is needed. It it’s a total coke bottle and was designed in China in the 1960s with no Israeli help.

 

[fltworthy]

I know enough about area ruling to see it on the F-17/18, one of those planes of the 70s and 80s you just said don’t have it… You don’t need to ‘coke bottle’ a fuselage to equalise transonic drag across the length on aircraft.

Every design is a compromise. If you compare the original YF-17 to its F/A-18 offspring, you will notice that the airplane was not only enlarged, but that it also filled out. Its lines are no longer as clean. Most modern fighters are biased towards the air-to-air role, which makes such details as area ruling less important than raw acceleration, or finding space for all of the electronic add-ons that arrive on the scene. The F/A-18 compromised on its enforcement of area ruling because - like so many other modern fighters - it was less important than other requirements. The Lavi was an exception - precisely because it was not an air-to-air fighter first, but a long range strike fighter. The Israelis did not compromise their application of area ruling because they were trying to squeeze that extra margin of range out of the airplane. That philosophy was extended to the J-10, even when it might have been less necessary.

I have constantly maintained that Israel had major input into the J-10 design and build. The key point of contention I have rejected is that the J-10 is a copy of the Lavi.

I don't believe that I ever suggested that the J-10 was a "copy" of the Lavi. What I have suggested is that the J-10 owes far more to Israel's Lavi experience than it does to the design of the MiG-21 (or any other Russian aircraft).

What actually happened with the J-10 is that after Glasnost/Perestroika/Tiananmen the Chinese lost access to American/European technology but gained it to Soviet. So suddenly they could brush off the old J-9 with a decent engine.

The J-9 was radically different from the J-10. Its inlets were mounted on the sides, not the belly. The Chinese were evaluating whether to implement a fixed canard, or possibly a canard with a hinged control surface (much like the Viggen) - not an all-moving control surface like on the J-10 or Lavi. The J-9 was statically stable - the J-10 is not. The J-10 owes far more to Israel's experience with the Lavi than it does to the J-9.

The Israelis could not offer China the opportunity to build a Lavi or even a big Lavi because there is no way the Chinese could build such a composite intense aircraft.

With respect to the selection of materials used in the J-10, I believe that already alluded to that in an earlier post:

Let's make this clear: the J-10 is not a copy of the Lavi. It is a much larger airplane, built out of Israel's experience with the Lavi, and built around the Russian engine and local manufacturing capabilities available to the Chinese.

The fact that they could not use the same composite technology that went into the Lavi, however, does not mean that the Israelis could not scale from their existing Lavi experience.

So if the J-10 is a scaled up Lavi one would expect some wing similarity?

The Israelis could not photo-scale from one airplane to the other. When you scale up a design, the volume and weight will scale as the length cubed, but the wing area will scale as the length squared. To maintain a similar wing loading, therefore, the developers of the J-10 had to increase the wing area more than they increased the length or height of the airplane. Add to that restrictions placed on the wing span of the airplane (to minimize changes in inertial moment relative to the original design), and of necessity this was going to lead them to a different wing configuration.

What is more surprising is that the J-10 did not turn out to look more different from the Lavi than it does. During the decade leading up to the launch of the Lavi program, IAI conducted a range of concept studies - both twin engine and single engine fighters, both air-to-air and air-to-ground platforms - including detailed layouts for the structures and stores as well wind tunnel tests to evaluate control logic and aerodynamic response. Some of the proposals were truly radical departures from prior designs. Yet for the J-10 they selected a configuration that clearly reflected their Lavi experience.

The only logical conclusion is that the developers were trying to minimize risk. By adopting a design that could borrow as much as possible from the Lavi flight test program (including the control law validation) they could minimize both the cost of developing a new configuration, and the likelihood of any unexpected surprises.

The only contention is the implication that the F-16I was somehow a delay on ISD from the Lavi.

Just to clarify: the Lavi achieved the range and payload of a Block 52+ F-16I, in an airframe with the empty weight of a Block 10 F-16A. Although it is a great airplane, the Soufa is not a one-for-one equivalent to the Lavi. Its wing loading is much higher, which impacts its ability to evade its opponents and defend itself over the battlefield. I am not saying that the Lavi should not have been cancelled. Without a partner who could boost the total procurement of the airplane to something more in line with the 300 aircraft originally envisioned, the cost of the Lavi would have been prohibitive - much like that of the Rafale today. But it should be evident that Israel (and their US partner, Grumman) lost the opportunity to produce an amazing strike jet.

 

[fltworthy]

For my side of it I was outraged to see such a vicious personal attack against someone who obviously is not on this forum and unable to defend himself (Zakheim).

Zakheim was a public official, who was playing in a politically charged arena. If he didn't want to open himself up to criticism, he shouldn't have taken the job.

As I said, I have little patience for bureaucrats who don't understand aviation, but who nonetheless feel entitled to make technical decisions that they know nothing about. I've seen too much of it in my day.

As Zakheim freely admits in his book, his assigned task was to "terminate" the Lavi - not to understand why Israel launched the program or what they hoped to achieve from it, not to ensure that Israel received maximum bang-for-buck for the military aid that they received - but to "terminate" the Lavi, regardless of the consequences. Zakheim admits that he "sat on" the approval of key Lavi contracts in an effort to delay the program (and further drive up its costs), until both the President and the US Congress intervened and forced Defense Secretary Weinberger to release the paperwork. Zakheim freely admits that he had to conceal what he was doing from Secretary of State George Shultz - who would otherwise have intervened earlier and ensured that the President enforced White House policy on the Secretary of Defense.

Nowhere in Zakheim's book will you find an assessment of what the Lavi was really intended to do, or what features made it unique. Zakheim didn't know, and just plain didn't care to know. Again, to use Zakheim's own words, in his view "A fighter was a fighter was a fighter."

Sorry, but I have no respect for the bureaucrats who clog our system and hinder fact-based decision making. Call it personal experience.

 

[Abraham Gubler]

To avoid mutal, self tail chasing I’ll focus on some key points for response.

The Israelis could not photo-scale from one airplane to the other. When you scale up a design, the volume and weight will scale as the length cubed, but the wing area will scale as the length squared. To maintain a similar wing loading, therefore, the developers of the J-10 had to increase the wing area more than they increased the length or height of the airplane. Add to that restrictions placed on the wing span of the airplane (to minimize changes in inertial moment relative to the original design), and of necessity this was going to lead them to a different wing configuration.

A wing configuration that just happens to mimic that the Chinese already had?

This is the Occum’s Razor moment:

Is it more likely that the J-10 was a completely white sheet design in which the Israelis scaled up the Lavi and just happened to achieve a virtual identical design to the exsisting Chinese J-9 centre barrel and wing?

[OR]

Is it more likely that the J-10 took the wing and centre barrel of the J-9 and added all these nice, proven Israeli Lavi design features to it to make for a much better aircraft?

Just to clarify: the Lavi achieved the range and payload of a Block 52+ F-16I, in an airframe with the empty weight of a Block 10 F-16A. Although it is a great airplane, the Soufa is not a one-for-one equivalent to the Lavi. Its wing loading is much higher, which impacts its ability to evade its opponents and defend itself over the battlefield. I am not saying that the Lavi should not have been cancelled. Without a partner who could boost the total procurement of the airplane to something more in line with the 300 aircraft originally envisioned, the cost of the Lavi would have been prohibitive - much like that of the Rafale today. But it should be evident that Israel (and their US partner, Grumman) lost the opportunity to produce an amazing strike jet.

These are sentiments I share and have written in this thread earlier on. The Lavi would have been a great plane. Extremely survivable, very smart and long legged. The only thing it lacked was LO. Though with its small size and nature of its design it would have leveraged the kind of LO treatments available to 4th generation fighters very well.

Zakheim was a public official, who was playing in a politically charged arena. If he didn't want to open himself up to criticism, he shouldn't have taken the job.

As I said, I have little patience for bureaucrats who don't understand aviation, but who nonetheless feel entitled to make technical decisions that they know nothing about. I've seen too much of it in my day.

Zakheim does not deserve this kind of criticism because you are scoring him with motivations he did not have. He recognised that the Lavi was the ideal plane for Israel. But he also recognised – rightly – that Israel could not afford it in the middle of a economic recovery program. If Lavi was happening now then Israel could afford it. But not in the 1980s.

At the end of the day it was the Israelis that killed Lavi. Even the IDF/AF voted against it. Zakheim just provided them the mechanism to pursue alternatives. If the Lavi had been built in Bethpage it would all be different but it wasn’t so it had to be caned.

 

[fltworthy]

Is it more likely that the J-10 was a completely white sheet design in which the Israelis scaled up the Lavi and just happened to achieve a virtual identical design to the exsisting Chinese J-9 centre barrel and wing?

The J-9 had side mounted inlets, the J-10 has a chin mounted inlet - resulting in fuselage sections with radically different load bearing structures. Furthermore, as I pointed out earlier and as you acknowledged, the center-fuselage structure of the J-10 including its arrangement of fuel tank and access panels, was modeled after the Lavi and F-16, not the J-9 and certainly not the MiG-21. How do you go from this to describing the J-10 as having "a virtual identical design to the exsisting Chinese J-9 centre barrel and wing"?

Zakheim does not deserve this kind of criticism because you are scoring him with motivations he did not have. He recognised that the Lavi was the ideal plane for Israel.

How do you arrive at this conclusion from Zakheim's book? Where in his book does he describe the Lavi as the "ideal plane for Israel?" Where does he ever describe the performance and features behind the Lavi that made it the unique program that it was? Quote us the passage, if you think you can find it.

There was no analysis of capability in Zakheim's work, no comparisons of range, payload, or sorties needed to deliver equivalent amounts of payload on target. Zakheim wouldn't know an aileron from an airspeed indicator - and didn't care to learn. He was a bureaucrat, doing what bureaucrats do best.

At the end of the day it was the Israelis that killed Lavi. Even the IDF/AF voted against it.

Just to clarify on this: the subject of the Lavi was a dividing topic within the IDF. Outgoing Air Force Chief Amos Lapidot was a solid Lavi supporter to the very end. Incoming Air Force Chief Avihu Ben Nun was always an opponent of the program, from day one. If you wanted to understand why the two men took up such different views, you'd have to understand their different roles and views coming out of the Yom Kippur War.

The Lavi was launched at a time when Israel's domestic military budget (not including US military aid) amounted to over 20% of Israel's GDP - an unsustainable level. The original vision of buying 300 (some said as many as 400) Lavi fighters for the IDF was simply not realizable. Cutting the number of aircraft purchased by half would have increased the unit cost by over 50% - making the Lavi uneconomical, unless IAI could find an alternate buyer capable of absorbing another 150 orders.

Getting back to the original topic of this thread, the same problem would exist for the development of a domestic Israeli stealth fighter today. It is not the technological hurdles that would prevent Israel from undertaking such a task (assuming that the US agreed to supply the engine). It is the economic hurdle. Even today, the IDF is talking in terms of purchasing perhaps 90 F-35 fighters. That's nowhere near the 250 fighters that the USAF uses as a benchmark for achieving a "learned out" production process.

 

[Abraham Gubler]

The J-9 had side mounted inlets, the J-10 has a chin mounted inlet - resulting in fuselage sections with radically different load bearing structures.

I was referring to the aft part of the fuselage which contains the engine. Same size engine, same size fuselage from J-9 to J-10. Also same wing. Wings and engines being pretty fundamental to aircraft. Sure they cut out the fuselage forward of the engine and replaced it with a Lavi derived structure as well as other tweaks. But the continuity of the core structure from J-9 to J-10 is evident. If the J-10 had just been a clean sheet scaled up Lavi then they could have kept the swept delta, multi spar wing. You can build these from aluminium and such has been done since the 1950s.

I think we’ve probably exhausted this issue far beyond the point of any potential conciliation of public benefit. So…

Getting back to the original topic of this thread, the same problem would exist for the development of a domestic Israeli stealth fighter today. It is not the technological hurdles that would prevent Israel from undertaking such a task (assuming that the US agreed to supply the engine). It is the economic hurdle. Even today, the IDF is talking in terms of purchasing perhaps 90 F-35 fighters. That's nowhere near the 250 fighters that the USAF uses as a benchmark for achieving a "learned out" production process.

Since Israel can get local content into their F-35I there is little case for a domestic alternative. I’m sure their efforts into LO are more likely to find a home in UAVs and long range precision weapons.

 

[fltworthy]

If the J-10 had just been a clean sheet scaled up Lavi then they could have kept the swept delta, multi spar wing.

As I pointed out previously, the developers of the J-10 could not directly photo-scale from the Lavi to the J-10. As I pointed out, while volume and weight will scale with length cubed, the wing area will scale with length squared. The wing area therefore had to be increased by a greater factor, in order to maintain the same essential wing loading seen on the Lavi.

As I also pointed out earlier, the developers of the J-10 also could not simply scale-up the Lavi wing, with the same exact aspect ratio, if they expected to retain similar handling qualities. Increasing the wing in that fashion would have radically altered the inertial response of the fighter. Think of it in terms of a figure skater who's entering a spin. When they pull their arms in, they spin faster. When they extend their arms out, they spin slower. If the J-10 had increased the wing area of the Lavi to maintain equivalent wing loading, and had also maintained the same swept wing geometry and aspect ratio, the roll rate of the airplane would have suffered. To maintain roll response while simultaneously increasing the wing area, they had to reduce the wing aspect ratio.

Maintaining roll response would have been essential, if they wanted to maximize their ability to transpose the control laws from the Lavi, onto the J-10. Roll response is also an essential element for air combat maneuvering, allowing the airplane to rapidly cycle between maneuvers. A fighter does not simply "turn". You must roll the aircraft and then pitch-up to achieve maximum turn performance. In his 2008 interview, China's chief test pilot for the J-10 confirmed the aircraft's excellent roll rate - which he described as far superior to the J-11/Su-27/Su-30 family of aircraft.

Same size engine, same size fuselage from J-9 to J-10. Also same wing. Wings and engines being pretty fundamental to aircraft. Sure they cut out the fuselage forward of the engine and replaced it with a Lavi derived structure as well as other tweaks. But the continuity of the core structure from J-9 to J-10 is evident.

You are right to note that there are distinct differences betwen the Lavi wing structure and that of the J-10. As I pointed out previously, the J-10 was "built out of Israel's experience with the Lavi, and built around the Russian engine and local manufacturing capabilities available to the Chinese." The Chinese did not have the composites technology necessary to duplicate the Lavi wing on a larger scale - nor could the Israelis provide the Chinese with that technology. Although IAI had conducted the detail design and component manufacture for the Lavi's composite canard, speed brakes, and ventral strakes, the wing structure had been designed and built under contract in the US by Grumman Corp. Passing along the composite layup technology that went into the wings would have required US approval, something that they were not likely to obtain.

The J-10 wing structure, however, is also distinctly different from that of the J-7 (MiG-21) or any other Chinese-produced fighter which preceded it. The main wing spar on the MiG-21 is located at roughly the 30% chord line. Most aircraft, the J-10 included, place their main wing spar closer to the 20% or 25% chord line. The control surfaces on the J-10 wing, including the actuator placement, are also very different from those seen on the MiG-21 or J-9. The actuators on the J-7/MiG-21 for example, protrude above the wing - where they can interfere with the low-pressure flow responsible for producing lift. Those on the J-10 are under the wing. The hinge line for the ailerons on the J-7/MiG-21 family of aircraft is further aft than the hinge line for the inboard surfaces (which on the MiG act as flaps and not as elevons). The J-10 meanwhile, maintains a common hinge line between both its elevons and its ailerons. These and other feature on the J-10's wing closely resemble the wing spar structure and control surface arrangement seen on Israel's Kfir fighter - which was itself a derivative of the Mirage III. This is where the developers of the J-10 turned to for experience - not the MiG-21 or any other Russian fighter.

 

[fltworthy]

Since Israel can get local content into their F-35I there is little case for a domestic alternative.

I would caution, however, that the issue of local, Israeli content for Israeli F-35s is not entirely settled. The agreement very nearly fell apart, because the US was unwilling to allow the IDF to integrate an indigenous Israeli electronic warfare suite into the F-35 - as Israel has done for all other US fighters supplied since the late 1970s. The agreement finally reached did not fully resolve this issue. It has only been delayed to a later date. IAI will be manufacturing elements of the wing structure for Israeli F-35s, but there is still no agreement on the installation of Israeli EW hardware on the initial batch of 20 aircraft - only an agreement that the US and Israel will continue to negotiate for possible, additional Israeli content on later batches of fighters.

For Israel this is a crucial matter. Many Israeli pilots died in 1973 because the electronic warfare systems that the US was willing to provide were unable to counter the Soviet SAM batteries deployed by Egypt and Syria at the time. Ever since then, Israel has insisted on developing their own electronic warfare gear, so that they can be sure that they have the latest technology and are not dependent on what the US is and is not willing to export.

By the time that Israel completes delivery of the first 20 F-35s in 2017, and negotiations begin for follow-on buys, there will no doubt be another round of wrangling over whether Israel should buy additional copies of the F-35, or hold out for a better deal with the purchase of the Next Generation Air Dominance (NGAD) fighter, due to enter production for the US Navy and USAF between 2025 and 2030. NGAD is expected to be a bigger airplane, with more range and payload - potentially a much better fit for what the IDF is looking for.

 

[TrangleC]

I must admit that i did not read through all 4 pages of the thread, so please excuse me if i repeat or ignore something somebody else wrote.

Regarding the "can Israel (or somebody else) afford a stealth aircraft?"-issue:
Has anybody heard of the Messerschmitt Lampyridae?
Lampyridae

It was a supersonic stealth fighter developed by the German company between 1981 and 1987.

They came pretty far - even had a flying (3/4 scale) prototype that met and proved the calculated stealth abilities - and it cost them less than 5 Million Dollars!

What is so interesting about this project is that while today the word 'Stealth' is synonymous for super expensive high end technology, the Lampyridae actually was an attempt to make fighter aircraft simpler and cheaper by exploiting stealth characteristics.
How?

Their trail of thought was roughly as follows:
With modern self guiding missile technology classical dog fights become less and less likely, so perhaps all the design elements of a fighter aircraft that are meant to increase its dog fighting abilities are (or soon will be) just unnecessary dead weight and make the aircraft more complicated than it has to be. If dog fights are sort of an dying art, then a future fighter would not need a gun and more importantly (regarding making a design complicated and expensive) would not need to be very maneuverable.
They figured as long as superior stealth characteristics would enable a fighter to sneak up on a target, shoot it down from afar with missiles and escape without being detected, it wouldn't need the ability to outmaneuver anything. Imagine how much cheaper a aircraft design could be if it basically is just designed as a stealthy, fast flying rod, without many adjustable wing surfaces (rudders, canards etc.) or thrust vectoring and stuff like that.

Considering all the fighter designs that were developed and build in the last decades, it seems the Messerschmitt engineers were not right in that regard, but on the other hand, isn't that sort of the direction all those unmanned stealth aircraft that are designed nowadays are going? Perhaps the Lampyridae was not a stupid idea after all, but just ahead of its time.

However, my point is that 'stealth' doesn't necessarily have to mean "terribly expensive", so i don't see why Israel shouldn't be able to develop a stealth fighter. I imagine the availability of cheap computer technology, better engines and modern composite materials would make it easier than in the early 80s and since the aircraft doesn't have to be manned anymore, a 'going cheap' approach wouldn't endanger the life of your/their own pilots.

 

[Feanor]

You still need a powerful radar, and modern avionics. That's first off. Second off the Israelis need ground-attack capability. Major ground attack capability. The fighter isn't just an interceptor or air-superiority fighter, it needs to be a full fledged multi-role, possibly even more of a strike fighter. Third off Germany had been manufacturing its own aircraft for quite some time, where as Israel has stopped doing so, and instead gone down the route of niche capabilities, specifically EW, inserted into imported platforms. Fourth they had only done basic airframe design. This is a fraction of the cost. They had no engine. No avionics. No radar. Really nothing except an airframe, and even that was far from complete. This is not to say that they couldn't have finished the project but rather to say that they chose not to, and hence why the costs were so low.

Israel is specifically looking for a 'gold-plated' in terms of capabilities, fighter, not a budget design of limited utility.