China was interested with J10 like intake since later 1970s'. This magazine was Youth Secience on 1979.
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The nearest time of similiar intakes came to China was 1987, the thunderbird visited China:
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that is partially true, I will tell you why that is not accurate.
Any one that knows about aerodynamics, I mean the basics, knows that aerodynamic studies take thousends of hours of research and development.
To put it simple, a wing or a taileron has many, many posible configurations.
These are for example distance between taileron and wing, vertical and horizontal distance.
aspect ratio, you can divide canards by aspect ratio, for example.
Wing position with respect the fuselage, trailing edge sweep or leading edge sweep, camber distance, wing airfoil shape and so on.
So that resaearch takes too much time and money, add avionics, structure, etc etc, and you find the average aircraft takes 5 to 8 years to be designed and 8 to 14 years to be flight tested.
the first evidence of IAI Lavi being the basis of J-10 is the visit J-10 design team made to IAI, this type of visit is not to drink tea but to exchange data, why? simple research takes time, so with money you buy data that reduces design and research time
this shows the original J-10 had several configuratoins studies but look at the main wing and you see it is very similar to the IAI Lavi wings
this shows you that IAI went to study several wing airframe configurations just to get to Lavi final shape
An early IAI Lavi configuration with a boxy intake, racked inlet lips shape like J-10
J-10 mockup with Lavi type pitot intake
The strongest admission of Israeli involvement in the J-10's development by Israeli authorities appeared in a statement made by an official as American authorities investigated alleged Lavi technology transfers to China. Without mentioning either Lavi or J-10, the Director General of Israel's Ministry of Defense David Lari "acknowledged in an Associated Press interview that 'some technology on aircraft' had been sold to China and that some Israeli companies may not have 'clean hands'".
In May 2008, Jane's Information Group reported several interviews with Russian sources claiming to be involved with various Chengdu military projects. A number of engineers, designers and technical specialists described their visits to Chengdu and other areas of China in the 1980s. A source alleged that high-level Chengdu officials described the possession of a single Lavi prototype at one of Chengdu's facilities. They also claim that in 2000, two years after the J-10's maiden flight, aerodynamic models were sent to Russian wind tunnel testing facilities to study the J-10's aerodynamics.
During the 2006 Farnborough Airshow, the Russian Siberian Aeronautical Research Institute (SibNIA) confirmed its participation in the J-10 program. According to the article, this participation was limited to observation and instruction as "scientific guides." The sources also called the J-10 "more or less a version of the [Israel Aircraft Industries] Lavi", but also a "a melting pot of foreign technology and acquired design methods" Left unelaborated is the degree of Israeli participation - if any - in J-10 development.
Kommersant's reporter Kostantin Lantratov affirmed that Russian consent was required to export the J-10, given its Russian AL-31 engine.
It has been reported that composite materials tested in the Delsen Testing Laboratories in Glendale, California during the year 1990 were related to the J-10 project.
Aircraft combat Chengdu J-10 Annihilator
www.machtres.com
This Yakolev prpject was ahead of its time, but if you see it shows you the path J-20 had, canards were chosen due to the advantages they offer over tailerons in terms of instantaneous turn rate.
Now for J-20 in order to be designed needed not 1 or 2 configurations but many configurations, it is obviously they copied and studied F-35 and MiG 1.44, but definitively the Lavi experience left some inprint on J-20
So to put it simple J-10 has a wing and landing gear position repeating the same configuration. the ventral fins and trailing edge wing extension are the same configuration, in order to be that similar they needed direct participation from IAI.
Lavi had many innovative solutions in structure and aerodynamics with respect the wing arragement, these were Israeli solutions, J-10 took over those studies there is ample evidence of it.