JF-17 Thunder Multirole Fighter [Thread 6]

[SQ8]

Two missiles which would be readily available to PAF are PL-10 and A-Darter and unfortunately both are in development phase as of now. As per the news, first A darter would be in service in 2016 and missile exports would began as early as 2017. It would further take two years to integrate the missile on any new aircraft. Seeing MAR-1 took 5-6 years to be in service of PAF from deal signing to integration of missile on mirages to be in PAF inventory, A darter in PAF inventory would be at 2021-2022 at the earliest

SA and Brazil to collaborate on missiles post-A-Darter | defenceWeb


For PL-10, no news about it's development cycle, but seeing how A-darter program going, a suitable guesstimate would be 2020 at the earliest if PAF sign deal in next one or two years for 5th generation SRAM with either china or Brazil-South Africa

The Chinese dont really seem to have an issue with seekers(referring to the system I mentioned earlier that is operational with high target discrimination). So I am guessing it may be the missile itself that could be the issue. In either case, the horses leading the program were not to worried about a HOBS when asked so back in 2011. Why that is so was/is beyond me.

 

[Windjammer]

What a difference would a couple of extra stations make.....thus an extra drop tank and a second c-802.

 

[Bratva]

The Chinese dont really seem to have an issue with seekers(referring to the system I mentioned earlier that is operational with high target discrimination). So I am guessing it may be the missile itself that could be the issue. In either case, the horses leading the program were not to worried about a HOBS when asked so back in 2011. Why that is so was/is beyond me.

Lower threat perception plus availability of HOBS from trusted suppliers plus a limited HOBS capability would be one of many reasons they were not too worried.

As per my understanding, they would target an all out hobs/hmds with Block-III. For now they are sticking with basics, Maturing Basic BVR, WVR, IFR, upgrading EW , Data links and sharing of info with groups ( which would be a new thing for pilots) and developing playbook of strategies of how to utilize all of it in an optimum way

 

[VelocuR]

Will it upgrade only 2 SD-10A to 4-6 multi-missiles?

 

[gambit]

@gambit

Just wanna ask about launch rails, JF-17 launch rail looks odd as compared to the launch rails of F-16. What do you think about launch rail of JF-17, would it put more stress on wing as compare to the launch rail of F-16 ?

You touched on a not very glamorous but very important subject.

We all know what is centripetal force so am not going into details on that here. Because of centripetal force, the weight limit on the F-16 missile rail launcher is about 160 kg or 350 lbs. But that is not all there is about these devices.

What is the center of mass of an object ? And how important is it ? In high performance motorcycles, the idea of 'mass centralization' is important, it can mean winning/losing races.

Mass Centralization

Motorcycles are naturally mass centralized because of the vertical “sandwich” of rider, fuel, and engine. The only masses that are not centralized are the wheels, but the developmental events of the past 40 years have greatly lightened wheels, tires, and brakes. No one company has led this process; really, racing has accomplished it.

If you look at the recent street motorcycle designs, many of them moved towards this idea, most noticeably having the exhaust silencer, often several kgs, moved to underside of the motorcycle. In the past, we have this mass off center: to the rear and to either port or starboard, affecting stability and controllability during rapid maneuvers.

Missile designs are designed similarly, as in we want to have as much 'mass centralization' as possible, and it is even more important when the missile is carried on an aircraft. Rocket fuel, solid or liquid, is an expendable mass. But solid fuel have an innate advantage over liquid fuel -- slosh. Or rather solid fuel do not slosh -- move -- under intense maneuvers. Motorcyclists know very well the different behaviors of their bikes between empty, half empty, and full fuel tanks.

Here is an example of the importance of center of mass in rocket design...

Rocket Control

The motion of any object in flight is a combination of the translation of the center of gravity and the rotation of the object about its center of gravity, which is also called the center of mass.

So what does this have to do with air-air missile rail launcher designs ?

Here is a reasonably accurate breakout of the AMRAAM...

http://fas.org/man/dod-101/sys/missile/amraam-5.jpg

Look at the propulsion section. Once the missile is in flight, the missile have to deal with the forces of physics on its own according to the NASA lesson above. However, UNTIL the missile is launched, it is the parent aircraft who has to deal with the forces of physics that acts upon the missile while it is still attached to the aircraft, all 160 kg of it.

It is important that the rail launcher have the missile's center of mass in line with the wing's strongest supporting members going all the way back to the wing root. Remember centripetal force. We have a 160 kg mass attached to the outer most reach of the aircraft -- the wing tip. This body is not uniform like a ball, but like a tube and the internal volume of this tube are not uniformly filled.

We can have the rail long enough to hold the missile, but if the missile's center of mass if in front or towards the rear of the wing tip, we can do serious structural damages, such as deformation due to twisting forces, to the wing itself. And if the maneuvers are intense enough, as in a 9g capable aircraft, we may even rip the entire contraption off the wing tip under those intense maneuvers. Not only that, we WILL launch the missile while under those intense maneuvers, and if the missile's attachment to the wing is not stable because its center of mass is not supported by the most powerful member of the wing, missile launch WILL be erratic, the missile may lose flight stability which will affect targeting which will result in a miss.

As far as the rail launcher for the JF-17 goes, I am confident that Pakistani engineers have all the physics and the math figured out and designed an appropriately robust device. So the issue, not problem, to me, is more about potential future upgrades. If the physics and the math says the wing cannot handle more the so-and-so mass at the wing tip, the JF-17 will be limited to whatever current load it has today.

 

[SQ8]

As far as the rail launcher for the JF-17 goes, I am confident that Pakistani engineers have all the physics and the math figured out and designed an appropriately robust device. So the issue, not problem, to me, is more about potential future upgrades. If the physics and the math says the wing cannot handle more the so-and-so mass at the wing tip, the JF-17 will be limited to whatever current load it has today.

That has to do with the construction of the jet as such. Unlike the F-16 with its honeycomb design throughout the wing; the JF-17 is very conventional in construction with sheet metal over spars.

 

[Donatello]

What I keep wondering about is why the PAF is persisting with the PL-5E-II. While it is comparable to the AIM-9M-8(in manoeuvrability and off boresight ability with a slightly better seeker) it would seem prudent for the PAF to simply focus on a new dogfight missile for its flagship jet. especially when it has done so already for certain older platforms within its inventory.

If the missile as you mention is of Chinese origin, what makes you think PAF has not already mated it on JF-17 and just kept it under wraps? HOBS is a significant capability and in dog fights, could be the winning difference.

 

[gambit]

That has to do with the construction of the jet as such. Unlike the F-16 with its honeycomb design throughout the wing; the JF-17 is very conventional in construction with sheet metal over spars.

True. Material does affect load bearing capability.

 

[SQ8]

True. Material does affect load bearing capability.

I had this discussion with a GD engineer who worked on the viper.. this was the response I have posted here before but will reproduce. I was referring to a picture of the JF-17 where ripples appeared on the skin of the aircraft while in half loop.

My question

Having a debate with somebody on another forum regarding another jet.
I was hoping you could just gimme a quickfire on whether those ripples on the LERX are normal for aircraft performing maneouvers..or is this simply bad construction.

His reply

The ripples appear to be the result of thin sheet metal construction of the LERX. That area would have a high air pressure during a pull up. A better construction (but more expensive) would be a thicker skin or a honeycomb skin. The thin metal may have enough strength to hold the load, but it really looks bad.

 

[Informant]

Damn you guys are so knowledgable. Thanks learn something new everyday!

 

[gambit]

Regarding the importance of load bearing and load distribution for the rail launch system...

Simulation of the Sparrow Flight Vibration Environment

Laboratory and captive flight experiments were performed using an instrumented Sparrow III missile to evaluate the relative merits of direct mechanical vibration and reverberant acoustic noise tests as techniques for simulating the Sparrow captive flight vibration environment. For the laboratory experiments, the mechanical vibration and acoustic noise excitations were applied in accordance with a common response-controlled test specification. The resulting missile vibration data were then standardized and compared with the vibration levels measured during captive flight to determine their similarity in terms of directional, spatial, and spectral distributions.

Captive flight is when the missile is carried by the parent aircraft. Whatever structural stresses the missile incurred during captive flight, vibration in this example, will be transmitted to the parent aircraft. Off center load distribution will increase structural wear on the wing.

 

[alimobin memon]

I had this discussion with a GD engineer who worked on the viper.. this was the response I have posted here before but will reproduce. I was referring to a picture of the JF-17 where ripples appeared on the skin of the aircraft while in half loop.

My question

Having a debate with somebody on another forum regarding another jet.
I was hoping you could just gimme a quickfire on whether those ripples on the LERX are normal for aircraft performing maneouvers..or is this simply bad construction.

His reply

The ripples appear to be the result of thin sheet metal construction of the LERX. That area would have a high air pressure during a pull up. A better construction (but more expensive) would be a thicker skin or a honeycomb skin. The thin metal may have enough strength to hold the load, but it really looks bad.

A question , looks bad but is it bad for future of jf 17?

 

[UFO77]

Thanks for reply. I wanted a source from which you got the news. For the last so many years there was no news about WS-13. I want to have a source before I can celebrate.

Listed company announcements about capital construction to the subsidiary engine production line has released, this is absolutely authentic!

 

[Chak Bamu]

A question , looks bad but is it bad for future of jf 17?

No.

 

[araz]

Regarding the importance of load bearing and load distribution for the rail launch system...

Simulation of the Sparrow Flight Vibration Environment

Captive flight is when the missile is carried by the parent aircraft. Whatever structural stresses the missile incurred during captive flight, vibration in this example, will be transmitted to the parent aircraft. Off center load distribution will increase structural wear on the wing.

Gambit.
Thank you for your extremely informative posts. MY question is an elementary one.and to my mind if there is a mechanical way of carrying the missiles closer to the wings the pressure on the wings and possibly the RCS could be reduced. The mechanism would then unfold(to the normal position) prior to firing the missile. Why do planes not adapt this and what would be the technical difficulties in achieving this.
Response would be appreciated
Araz