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JF-17 Thunder - Information Pool

What does mean LERX ?

It is an English abbreviation of Leading Edge Root Extension who wants literally to say : Extension of the root of the leading edges.
Word corresponding in French is: APEX.


Where are they on the plane ?

LERX are the natural prolongations of the wings towards the nose of the plane. In some kind, they make the joint between wings and fuselage.

The F-18 has LERX of very great dimensions so much so that his manufacturer, Northrop (absorbed since by Boeing), had baptized "Cobra " the preliminary projetct due to the fact that this airplane seen on top resembled the reptile with these two surfaces behind the head.

All aerodynamic surface forming an angle higher than 30˚ with the axis of relative wind passing around it stalls, because the air passing on the upper face of this part changes from a laminar flow to a turbulent flow. The turbulet airflow create a fall of lift power. The wing takes down and the
plane falls!

This phenomenon is even more delicate at low speed due to the fact that the speed of the air moving on the top surface of the wing decreases
with the proper speed of the plane. Lift obtained by the wings being directly in relation with the speed of the airflow of the upper surface of
the wings, when the plane slows down, the lift power decreases.

It is possible to counter this phenomenon by 3 main ways:

- To increase speed obviously, but it's not what one seeks at the time of the landing for example...
- To increase the angle which the wing and the airflow are forming, this one being limited to 30˚ as we saw above.
- To increase camber of the wing. It is what we do when the plane extends the flaps and the mobile leading edges at the time
of landing or takeoff.

Militarily speaking, it is interesting for a fighter, involved in a dogfight for example, to decrease its speed as much as possible in order to let
a faster airplane go ahead. By this manoeuvre, the fastest plane of both go ahead of its adversary and then allows the slower airplane
stay behind him in position of shooting.

It is vital for the fighters to fly fast to be able to reach a zone of intervention as soon as possible, but it is critical too to be able to fly as slow
as possible while keeping the plane control in order to be able to ensure itself to remain behind the adversary and therefore in offensive
position.

In that way, the LERX provide a considerable supplement of lift at raised angles of attack, i.e. when the angle formed by the wings and the
relative wind direction due to the displacement of the plane increases.
Indeed, the LERX generate powerful swirls of air or Vortex which increase the air velocity on the roots of wings and around tails. This makes
it possible to keep the control of the plane at angles superiors of 30˚. These Vortices when are intenses are particularly visible,
materialized by the condensation of the moisture of air.

LERX also allow the correct air feeding of the engines during those flights at high angles.
Lerx

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Any idea about the JF 17 wingloading?. been looking for it for 2 years... a ground attack role is better to have a higher wing loading -
low wing loading is for performing at higher altitudes---multirole aircraft has to find a proper balance... would be interesting to know jft's



I was under the wrong impression that the jft design is actually a 2nd gen design , which was slightly updated , but having severe aerodynamic deficienies ...... this aspect had started to plague the thoughts of meny pdf members aswell

i was concentrating on the design evolution or lets say different schools of thought to stabilize the wing at high alpha , vortex generation/ fuselage lift---e.g double delta, lerx, levcon, canard fixed/movable


The tailplane serves three purposes: equilibrium, stability and control.

F-16 / f14 use ventral fins to improve lateral stability whereas in F-15/ F-18 dorsal and vertical fins are enough

Slats/Leading edge Flaps increase the coefficient of lift-increase the maximum AOA during low speed

LERXes improve AoA handling

The F-18 has a very low swept wing which gives excellent lift at low speeds and requires less pitch , AoA to achieve lift.The best wing for low speed is not highly swept, but moderate/low swept...most combat is in that region e.g f-18


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Aerodynamic improvements produced by leading-edge flap and forebody strake/lerx on f16
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based on the design of wings the jft aoa seems better than f16 and closer to the f18 which is famous for its aoa --- [prominent lerx/strakes---> upto 50% increase in max lift + low/moderate swept wing --> spin resistance]


LERXs & Canards, both basicly both generate vortices and add lift ahead of the center of gravity

Low aspect delta wing and High aspect canard configuration obtains the less drag and good lift-- thus used mostly in such designs , primarily for flight performance -- High lift on canard reduces its efficiency, increasing its efficiency reduces its lift.
http://www.defence.pk/forums/air-wa...acteristics-canard-non-canard-fighters-3.html

another thread being copy pasted by people on other forums....
 
According to a very long interview of the former PAC official (pupu 2007 year).

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The former PAC official said :

JF-17 PT-04 Max speed :2.0 mach,basic range:2000km+,weapon load: 3.9ton. combat range (with 3 fuel tank ): 1300km+


(old PT-01/PT-03 without DSI version : Max speed:1.6 mach, basic range:1800km, weapon load:3.6 ton).


This is a huge leap of JF-17 PT-04 indeed.


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link:

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Some google translation of the highlights of an old 2006/2007 interview

"Fierce Dragon" fighter training simulator in Russia show everyone eager to become the focus of an American pilot carries it with the F-16 for comparison

U.S. pilot-test "Xiaolong" picture

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Air Force F-16 fighter pilots Jiesenkelai come in "Fierce Dragon" fighter training simulator operation.
Photography : our old friend

"I feel good, and some of the major functions of the F-16 are very similar!" Jiesenkelai door visit to Mainz in "Fierce Dragon" on the operation of the simulator five minutes later, the "International Herald Tribune" so said. The Air Force F-16 fighter pilots maneuverability performance attracted a large crowd of visitors.

Digital function impressive

"International Herald Tribune" at the exhibition site, "Xiaolong" training simulator is the front wall of three large color LCD screen, simulated cockpit of vision. They also hung over the two smaller screen, showed the plane's air posture and the situation on the ground.

U.S. pilot-test "Xiaolong" picture

Training Simulator itself, in terms of exterior size, or internal settings are simulated real aircraft cabin built, it is not hatch. Chengdu Aircraft Design Institute engineers Fa told the "International Herald Tribune" : "This exhibition is only one Taiwan, but also the most basic 'Fierce Dragon' training simulator, production may, in accordance with customer needs to install the necessary equipment. The construction of an ordinary 'Fierce Dragon' Training Simulator thousands spent 10,000 yuan. The simulator can drill aviation, combat tasks that can help pilots familiar with the different altitude, distance and orientation, perception and momentum. "

Experience the "Fierce Dragon" Jason talked about it with the U.S. F-16 fighter distinction, also made special mention of the former cockpit panels operating on the three multi-function display, and much appreciated. He believes that, "Both the joystick and other equipment layout is also different." He smiled and told reporters : "Because of the shortness of time, not familiar with the 'Fierce Dragon' full functionality, I can not fully compare the performance of the two fighters. However, your new fighter digital functions impressed me deeply. "
 
Feb. 7, 2013 - 06:35PM | By Usman Ansari
ISLAMABAD — Pakistan is integrating its nuclear-capable Hatf VII/Vengeance VII Ra’ad air launched cruise missile onto its JF-17 Thunder aircraft, but analysts are unsure if this signifies a nuclear deterrence role for the aircraft.

Air Commodore Khalid Mahmood at the JF-17 Project Management Office said integration work was ongoing with Chinese and Pakistani weapons, and that “most weapons have been integrated”.

“Ra’ad and the H-4 [glide bomb] will be for the Block I and Block II” aircraft currently in or about to enter service, not just the forthcoming Block III variant, he said.


Former Air Force pilot and analyst Kaiser Tufail said, “It makes good sense to get on with the wiring as well as flight trials of these weapons on the JF-17 at this stage. For one thing, all subsequent production aircraft would have the mod integrated from the outset and there will be no need for retrofits that also result in long down times at the flight lines. Secondly, the whole process is lengthy and it was about time we started it.”

He added, “Possibly, by the time the mods are in place on the JF-17, the first of the older Mirages would be retiring.”

The Mirage III carries the Ra’ad and is the delivery platform for Pakistan’s airborne arm of its nuclear deterrent. Its avionics were upgraded in the 1990s under the Retrofit Of Strike Element (ROSE) program.

They have been in service for many years, however, and are approaching the end of their useful lives.

Most recent major military developments have aimed to strengthen the nuclear deterrent, such as the unveiling of the Hatf IX/Nasr battlefield ballistic missile and the submarine-launched variant of the Babur cruise missile.

However, analysts are uncertain if the airborne arm of the nuclear triad is set to be similarly strengthened with the introduction of the JF-17 in this role.

Tufail said the Ra’ad’s integration onto the JF-17 would be very beneficial.

“It would certainly add to PAF’s [Pakistan Air Force’s] stealthy ingress capability [due to low cross-section of the cruise missile], considering that the parent aircraft do not have it,” he said.

However, Mansoor Ahmed, from Quaid-e-Azam University’s Department of Defence and Strategic Studies, and who specializes in Pakistan’s national deterrent and delivery program, is unconvinced that replacement of the Mirages with the JF-17 is imminent.

“The Mirage is a tested and well-integrated platform, it would take some time to have the Thunder in large numbers to do the job”, he said.

“Secondly, how good are the Thunder’s ground attack/avionics capabilities compared to the ROSE Mirages?”

Tufail, who flew the Mirage operationally, does not see the Ra’ad-capable Mirages as “less credible as a nuclear deterrent in any way.”

“However, the JF-17 would certainly be a better and more modern platform, about which there should be no debate. As and when the JF-17s attain full operational capability with the Ra’ad, that role will be withdrawn from the Mirages, but that is not to mean that the Mirages would be retired — they do a lot more than just carry Ra’ads,” he said.

“The Mirages would be retired as they outlive their airframe hours or run out of spares support, which I see starting to happen over the next five years or so.”

Depending on the material state of the Mirage aircraft, Ahmed said they should give the PAF enough time to bring the Block III variant of the JF-17 into service, which is to have an improved avionics suite.

Mahmood said the avionics suite of the Block III variant is not yet finalized as the PAF is “looking for something to give more operational capability, and still examining avionics options.”

A perennial issue for the JF-17 has been the question of the continued availability of its powerplant. Currently, it is powered by a Russian Klimov RD-93.

It has been speculated for some time that the JF-17 will eventually be powered by a Chinese engine, a possible thrust vector control (TVC) variant of the Guizhou WS-13 Taishan.

Mahmood, however, would only say that the engine “depends on customers,” and that “we have options with regards to engines; we’re not restricted.”

Tufail is unconvinced a TVC variant is a necessity at present.

“Personally, I don’t see the JF-17 as a ‘do-all’ fighter, and I feel that it needs other areas to be looked at for modifications, rather than just follow fads,” he said.

“TVC helps in air combat maneuvering, whose days are numbered, if one goes by the technological developments underway. If that be true, it would make much more sense to focus on enhancing BVR [beyond visual range] capabilities, including radar and weapons, which need to be constantly upgraded during the life of an aircraft.”

The JF-17 is only rated to plus 8g, and for this reason Tufail said “the JF-17 cannot fully exploit the TVC potential, which a 9g aircraft can do far better.”

Analyst Usman Shabbir of the Pakistan Military Consortium think tank said the JF-17 airframe “can certainly handle more than +8g, but the restriction is in place to increase the airframe life.”

He said this “may be increased in later variants where more composites are used to increase airframe strength and reduce the overall weight.”

Despite Missile Integration, Nuke Role Unlikely for Pakistan’s JF-17 | Defense News | defensenews.com

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Urm.. there is no proof or even a hint of the IRIS-T ever being tested on the JF-17.
the Iris-T is capable of being fired from the JF-17(or any aircraft capable of firing the Aim-9)..
But the IRIS-T has not been and will not be for the future be part of the JF-17's arsenal.

The A-Darter was expressed interest in , looked at.. but never got beyond interest and initial negotiations.
The JF-17's current missile is the PL-5E-II which is roughly comparable to the Aim-9M.
There is a Chinese missile in development with greater capability that will mirror the capabilities of the A-darter and may be introduced in 2013.

The MAA-1-A piranhas were tested on the JF-17 but never meant for it, they are for another existing weapon system and have been paired with a HMS display.. that makes that system the current best dog-fighter in PAF's fleet(take a hint).

Currently the JF-17's arsenal also has an undeclared EO/Guided weapon system in development that is supposed to closely resemble the AGM-65 in performance. However, the priorities for all these various arsenal and capability upgrades is different.
But the program is focusing on first delivering a potent air-to air capability(with Electronics to complement)..then a SEAD&PGM weapon capability(with electronics to match)...and then finally stand-off capabilities(with electronics,software upgrades etc) to match.

So yes, it is a proper workhorse with weapons and capability(as much as our rivals..or rather the arm chair ones that post here try to down play it through what is best referred to as paper matching).. that gives the PAF some footing to put up a good fight(ruefully, its something that the actual professionals of our rivals..those that fly and fight understand..one would actually hope they were as simplistic as some of the posters here..but our enemy is fairly intelligent).

However, it is also not some overbloated fighter that does not have severe limitations.. and is not the best jack of all trades either. There is a need for a greater capability in the PAF to complement the F-16's that make up the main offensive punch of the PAF... but at this point.. due to lack of funds.. Nothing is moving.

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First revealed in 1995 as the successor of the cancelled Sino-US Super-7 project, FC-1 (Fighter China-1, max TO weight 12,700kg, max speed M 1.8, service ceiling 16,920m, max weapon load 3,900kg, ferry range 3,480km, combat radius 1,352km, max g load +8.5) is being developed by CAC/611 Institute (with some technical assistance from Russian Mikoyan OKB) as a "medium tech", light weight fighter/ground attack aircraft carrying a relatively cheap price tag (~$20m).

As a fighter designed for export, its main customer is expected to be Pakistan who also shares 50% of the total cost (around $150m). It may also compete with second-hand F-16s to seize the market created by the retirement of Mig-21s, Mirage III and F-5s.

Currently powered by a Russian RD-93 turbofan (upgraded RD-33, rated 8,795kg with a/b), it may also be powered by a locally produced WS-13 Taishan once the engine is ready. The A-6 style "V" shaped air-intakes are believed to provide smooth air flow to the engine at high AoA. The fire control radar is thought to be a Chinese KLJ-7 X-band multi-functional PD radar (track 10 and engage 2 simultaneously, look-up range 75km, look-down range 45km for RCS=3m2). A European high performance radar (e.g. Italian Vixen 1000ES AESA) has been planned in later batches.

Other electronics include an NVG compatible glass cockpit (EFIS) with three 8"x6" color MFDs, HOTAS, AIFF, 1553B data bus and INS/GPS. Weapon load includes both short (PL-5EII/PL-9C/AIM-9M) and medium-range AAMs (SD-10A). LGBs (LT-2/LT-3/GBU-16), GPS/INS guided bombs (LS-6), anti-radiation missiles (Brazilian MAR-1 or Chinese LD-10) and IRST/laser designation pod (WMD-7) can also be carried for ground attack missions.

Up to 2 C-802AK AShMs can be carried for anti-ship missions. For high value fixed targets, the new CM-400AKG standoff supersonic ASM can be carried. For self-protection purpose a KG300G ECM pod can be carried. The development schedule of FC-1 was repeatedly delayed caused by various problems, such as lack of funding, the reluctance of western countries to supply advanced avionics, as well as the revised specifications set by PAF to counter the threat from India's LCAs. These specifications included a true BVR attack capability with active radar guided medium-range AAMs (SD-10).

However, FC-1's prospect in the domestic market was not very promising, as PLAAF had largely committed to the more advanced J-10 as its new generation fighter along with J-11 and was reluctant to take a large number of FC-1s due to its less advanced design and a Russian engine. After lengthy negotiations, Pakistani government finally signed the contract with CATIC and CAC/611 in 1999 and gave the "go ahead" order to the much delayed project. The development was further accelerated after PAF recommitted the project and confirmed FC-1's technical specifications in detail in February 2001. A full-scale mock-up was quickly constructed. A total of 6 prototypes (01-06) would have been built at CAC. The 01 prototype rolled down the assembly line on May 31, 2003 with two small wing fences. Its maiden flight took place on August 25, 2003. The 03 prototype first flew on April 9, 2004 without the two small wing fences.

The 04 prototype was expected to fly by the end of 2005 with full suite of avionics but this was delayed until April 2006 due to several structural modifications. They include new diverterless supersonic inlets (DSI/Bump) similar to those of American F-35 to reduce weight and achieve better performance. A large rectangular-shaped fairing is installed on top of the vertical tailfin which may house ECM equipment. Its flight control includes a Type 634 quadruplex digital FBW in pitch axis and a duplex analog FBW in roll axis. A UV band MAWS has been installed at the root of the vertical tailfin to provide rear hemisphere coverage. Two enlarged F/A-18 style LERX are thought to offer higher AOA as well. The first flight of 04 prototype took place on April 28, 2006, and 06 prototype on September 10, 2006. The first two preproduction JF-17s (Joint Fighter-17, 00 batch/07-101 & 102) were delivered to Pakistan on March 2, 2007, with the nose-tip pitot tube removed. The 01 batch of 6 JF-17s (08-103 -- 08-108) were delivered between March and April 2008.

The contract for PAF to acquire 42 JF-17s (mostly assembled by PAC) was singed on March 7, 2009. The first two (09-109 & 110) have been built by CAC. The first JF-17 (09-111) in the batch of 4 assembled by PAC rolled out on November 23, 2009. It was reported in May 2011 that PAF plans to acquire another 50 JF-17s on an "expedited" basis as the production continues. Besides Pakistan, several Asian and African countries also expressed interest in FC-1, including Egypt, Bangladesh, Iran, Sri Lanka and Azerbaijan. FC-1 passed design appraisal in December 2009. The first taxi test of FC-1 powered by an indigenous WS-13 took place on March 18, 2010. A further improved version (JF-17A/JF-17 Block 2?) featuring an AESA radar, IRST and IFR probe has been proposed and is likely to be under development as well. The latest news (December 2012) suggested that Sri Lanka plans to acquire 6 JF-17s starting in 2013.
- Last Updated 1/17/13
Chinese Military Aviation: Fighters II
 
Canadian Journal: Pakistan improved JF-17 fighter for the Indian aircraft carrier
2013-02-27




Pakistan Air Force JF-17 fighter (pictures)
In Karachi, Pakistan Defense Exhibition on display at the JF-17 "Lightning" (known as the FC-1 "Fierce Dragon") attaches great importance to the remote on the ability to attack, sources in the Pakistan Air Force JF-17 is currently the most important task repeatedly raised improve multi-function performance, especially on the distal end of the air-to-ground strike capability of the ship. Foreign media said the implementation requires more powerful over the remote-to-ship missiles, ship strike capability for deterrence, India's aircraft carrier. It seems that China and Pakistan Air Force attach great importance to air attack aircraft carrier combat, and more remote weapons development for the JF-17.


Canada, "Han and Defense Review" magazine (in advance), in March, it was reported, sources in Pakistan and China, as well as weapons manuals are confirmed for the JF-17 air-to-surface missile developed CM-400AKG. This missile to Mach 5 supersonic attack a range of 200 km. Pakistani sources claimed that the Pakistani side has not purchased the the CM-400AKG, but the next stage will seriously consider imports.


In addition, a noteworthy trend is that once the F -15, F -16 fighter carrying similar to the CM-400AKG as weapons, but also constitute a more serious threat to U.S. aircraft carriers will be similar range of weapons may be farther. The CM-400AKG from the SY-400 surface-to-surface guided rockets, the rockets did not equip the Chinese army.


Defense Exhibition in Karachi on display with the JF-17 fighters with the Brazilian MAR-1 anti-radiation missile. This missile weighs 274 kilograms, 3.9 meters long, the warhead weight of 90 kg, a range of 60 kilometers, the flight speed of 0.5-1.2 Mach, passive homing and active laser fuze.


Pakistan in December 2008 and Brazil signed an agreement of the import of this missile, the number was 100, now mounted by the "Phantom" - III multi-role fighter, the future will be mounted to the JF-17. This JF-17 will need to bring China KG-300 series production of electronic warfare pods, KG-300G is mainly used for airborne radar jammer interference range of 6.5-17.5GHZ weight of 150 kg.


In addition, the latest of the Pakistan Air Force JF-17 manual also includes two new air-to-ground missiles, and also by the JF-17 carrying. "Hate Fu 8 remote on air-to-ground cruise missiles, with a range of 350 km, with a turbofan engine. JF-17 carries a second standoff projection weapons H-4 air-to-surface missile, with a range of 130 km, using GPS / inertial guidance, is said to also conducted several test-fired.


Reported that the missile with the JF-17, together with the description sent on the exhibition means that Pakistan has allowed the JF-17 with the above-mentioned weapons sold together.
These weapons from the quality point of view, this is a leap for the Air Force of the Third World countries, especially in the range of 350 kilometers, "Hate Fu 8 remote on the air-to-ground cruise missiles, China also did not launch similar weapons. Due to the limitations of international treaties, even if exports, Pakistan also need to range reduced to less than 300 km.


The equipment of the Pakistan Ministry of Defense official said, "The Pakistan Air Force's top priority is to improve the JF-17, rather than rush to the import of new fighter". This shows that the F-10 equipment plan is only a medium-and long-term planning, rather than the upcoming completion of the contract. Reported that so far the negotiations about the J-10 did not further the main problem is still the budget.


Reported that armed helicopter is also Pakistan's long-sought project. Pakistan Army has studied China's straight-9E, the latter with Turkey's T-129 helicopter fierce competition in Pakistan. Pakistan once expressed hope that the 15 T-129, but because of budget shortfalls, lack of progress. The straight -10 Straight -19 helicopter gunships, is designed for the Chinese Army, production, production is still insufficient, there is no export rights.

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