JF-17 Block-3 -- Updates, News & Discussion

[Thorough Pro]

No difference in materials just two different cameras, different resolution, different lighting conditions

Both Thunders in the picture are block 2 , but clearly different in materials used.

View attachment 632042

View attachment 632043

From what I can see , Block - 2 after serial numbers 2P-50 are same physical structure as block 3.
Earlier jets are different and may be too expensive to convert

 

[araz]

I'm not sure I can explain to someone who thinks the JF-17 uses "pulleys", how much there is wrong with what you've said. Just to correct you on 1 point, amongst the many, the current block I/II JF-17s already use FBW - digital in pitch, and analogue FBW in roll and yaw. The block III uses digital FBW in all three axis.

My friend
I am here to learn as well. So feel free to expalin how I am wrong. I am very happy to orrect ahatever mistakes I have made. This is part of our learning process.
A

 

[Safriz]

My friend
I am here to learn as well. So feel free to expalin how I am wrong. I am very happy to orrect ahatever mistakes I have made. This is part of our learning process.
A

You are arguing with people who are adamant they are right and you are wrong.
A futile exercise.

No difference in materials just two different cameras, different resolution, different lighting conditions

Ok ... As you say.....Khan saayb

 

[ARMalik]

You are arguing with people who are adamant they are right and you are wrong.
A futile exercise.

Its ok mate, we are all here to learn. Every day we learn something new even if we think the others might be on an incorrect path. End of the day, all the fellows here just want JF-17 to be much more successful.

By the way good posts from you and Raven, and others.

 

[araz]

You have valid points. However I will refer you to the mirage rebuild factory. Its doesnt take a year to strip a mirage and refit it. The same applies to other fighters. You have used the term centre of gravity. How is the loading of the air frame so altered that the COG shift is so significant that major structural changed are required? Pulley and FBW....you make jf17 sound like the wright brothers experiment. Come on yaar.

Ok anyways it's almost iftar time. I bid you farewell and a good day.

OK.
Please educate me in how a analogous FBW is converted into a Digital FBW. I dont remember where the pulley bit came from but I haveread it somewhere. I dont have enough knowledge to be as confident on how things work so please do educate me.
A

 

[Trango Towers]

OK.
Please educate me in how a analogous FBW is converted into a Digital FBW. I dont remember where the pulley bit came from but I haveread it somewhere. I dont have enough knowledge to be as confident on how things work so please do educate me.
A

Just google it. Mashallah you are a smart guy

 

[Shabi1]

OK.
Please educate me in how a analogous FBW is converted into a Digital FBW. I dont remember where the pulley bit came from but I haveread it somewhere. I dont have enough knowledge to be as confident on how things work so please do educate me.
A

I think some confusion here, let me clear it out.

1. Conventional or legacy aircraft control systems are hydraulic similar in concept to a power steering etc. Cables and pulley system is ancient, that is for extremely basic flyer.
2. FBW is when a electrical signal is sent from the joystick and actuators (motors) control the flight surfaces. Since the signal travels through a wire its called fly by wire. Modern cars have Drive By Wire where the cables and mechanical systems replaced by actuators for throttle, hand brake and active steering etc.
3. FBW needs a computer to be controlled. Analogue computers are mechanical computers which use clever mechanisms to get certain outputs for a particular input. Digital computer is software+hardware and any jet being manufactured right now will have a digital computer as analogue computers are heavier and more expensive.
4. Newer version of FBW is FBW Optics or FBO. Here the data bus is fiber optic, electrical signal is instead of electric wire transferred via fiber optic cable. Fiber optic cables are much lighter in weight and offer more bandwidth which is more data can be passed reducing the number of cables. Also are faster but the weight benefit is the key factor.
5. Now some aircraft have relaxed stability designs for eg airliners, these if no input are by default fly in straight line. Dynamic stability is used for modern jets here the design is unstable and aircraft will have a tendency to for eg pitch up if let go, this makes the aircraft unstable but more manuverable. Here the FCS computer will constantly tell the FBW to change the flight surfaces without pilot input to keep the aircraft flying straight.
6. Another thing about FBW is it will protect the aircraft from over stressing. That is won't allow the pilot to pull a maneuver that could break the airframe and will keep him in defined limits.

Now coming to JF-17 PAC Kamra website. Which could be Blk-2.
https://www.pac.org.pk/jf-17
Flight Control System

• Composite Flight Control System comprising
  conventional controls with stability augmentation in roll
  and yaw axis and fly by wire in pitch axis
• Quad-redundancy in Fly By Wire System
• Autopilot with Altitude hold and Attitude hold modes

What this implies is JF-17 has a FBW+Hydraulic system (Composite). And the FBW has quad layer redundancy which is 4 digital computers with separate buses in case there is a failure. And in case of a electrical failure the hydraulic system is a back up as well. Also from DCS videos where they turned off FBW on JF-17 the JF-17 showed pitch up characteristic so the Pitch FBW means the FCS is constantly adjusting aircraft in pitch similar to F-16 controls.

Summing it up FBW is a pilot assist which makes it easier and safe to fly. Aircraft maneuverability is dependent on the aerodynamic design of the jet not FBW as most widely believed. Yes with FBW pilots fly more boldly and confidently so they push the aircraft more to the limits.

 

[The Raven]

Just to clarify, the "stability augmentation in roll and yaw axis" implies analogue FBW using an analogue flight control computer, and quadruplex digital FBW doesn't mean 4 separate digital FCS computers, but that 4 discrete channels are used to determine the pitch input on the flight stick, usually 3 channels are used to derive an average and then compared with the fourth channel as a reference to determine whether there is any discrepancy. There's usually 2 digital FCS computers, one acting as the backup. Analogue FBW systems were used in early block F-16s and F-18s. The JF-17 has neutral static stability (CoG inline with CoL), similar to the F-18A/B/C models, and the Typhoon is largely neutral in longitudinal pitch axis. There are certain pros and cons with having relaxed/neutral static stability, a highly relaxed design will naturally tend to pitch up as the CoG is aft of the CoL, but the downside is greater trim drag, while a neutral design may not be as quick in pitch momentum, but have less trim drag issues, and a more stable gun and bomb platform. The early gen F-18A/B/C Hornets were neutral designs as they were optimised for attack missions, while the later D/E/F models with larger wings, tailplane, LERX and more powerful engines were unstable and used digital FBW and had improved air-to-air capability. The Typhoon uses long coupled canards to achieve greater pitch momentum, while the JF-17 uses large LERX to achieve similar vortex induced airflow for greater pitch agility. All designs are a trade-offs to a certain extent, and multiple methods can be used to achieve similar results, such as canards, LERX, and flight control laws.

 

[LeGenD]

I will now speak to you in the language you understand. Thank Allah its Ramadan

Point taken re yaar.. rude idiot
You are pathetic and lazy. Go learn and if you cant your problem not mine

Why do I need to teach you? Will you pay me for my time? This is a discussion forum not a class room . Am I your father that I should invest time with a nalaik insan like you who cannot google and has not learnt basic manners

Dont refer to me again. Jahil
@Shabi1 and @The Raven have gone out of the way to post for your single cell brain but you want me to hold your hand

Having a bad day today, my friend?

Please exercise calm and better judgement in your exchanges much like member Shabi. This is bordering on abuse.

 

[araz]

I will now speak to you in the language you understand. Thank Allah its Ramadan

Point taken re yaar.. rude idiot
You are pathetic and lazy. Go learn and if you cant your problem not mine

Why do I need to teach you? Will you pay me for my time? This is a discussion forum not a class room . Am I your father that I should invest time with a nalaik insan like you who cannot google and has not learnt basic manners

Dont refer to me again. Jahil
@Shabi1 and @The Raven have gone out of the way to post for your single cell brain but you want me to hold your hand

I have deleted my post which irked you. I would suggest you delete yours as well. I have thanked both @ Shabi and @The Raven for their contributions.
Regards
A

 

[Trango Towers]

I have deleted my post which irked you. I would suggest you delete yours as well. I have thanked both @ Shabi and @The Raven for their contributions.
Regards
A

agreed. have a good day

Having a bad day today, my friend?

Please exercise calm and better judgement in your exchanges much like member Shabi. This is bordering on abuse.

alhumdulillah common sense prevailed. thank you for your kind advice.

 

[araz]

Having a bad day today, my friend?

Please exercise calm and better judgement in your exchanges much like member Shabi. This is bordering on abuse.

Boss.
If you could kindly delete your post it will remove the unsavoury invidence please.
Regards

 

[LeGenD]

Boss.
If you could kindly delete your post it will remove the unsavoury invidence please.
Regards

Good Sir, you humble me with that word. Please consider "bro."

My comment stay for the benefit of others as well.

 

[araz]

Good Sir, you humble me with that word. Please consider "bro."

My comment stay for the benefit of others as well.

Thank you.
Kind regards
A

 

[CriticalThought]

You are showing a systematic use of specious reasoning, that is based on deriving assertions that suit your purposes from arguments that have no relevance to the claims made. You come across as narcissistic, who doesn't just have a wish to prove himself, but a fetish to achieve intellectual superiority over others and derive comfort by insulting them. I have now seen this behavior from you over multiple threads. In detail:

The Block III aircraft have been upgraded with a new electronic warfare system based on the version on the J10-C, which includes, amongst other elements, the S740 airborne missile approach warning system using improved infrared MAWS as apposed to the UV based MAWS in Block I and II aircraft. See link below.

https://www.ainonline.com/aviation-news/defense/2020-01-02/more-thunder-chinas-air

You need to provide proof of the following assertions you have made earlier:

1. There is an EW system installed on the tail of Block 3.
2. This EW system needs air cooling.
3. This cooling is provided through the opening seen on the base of the tail in Block 3.

So far, you have provided no such proof. The website you have linked is not a proof of anything. What is written on that website is only an opinion that is not backed by any official or credible sources.

You seem to be hung up on making things EMP resistant as if that's the be all and end all. The FBW and databus changes were made to improve flight dynamics, save weight, free up internal space for the AESA, and improve mission computer performance and weapons integration. Are you saying the primary aim of improving the avionics was simply to make it EMP resistant? I don't think the PAF expects the indians to develop an EMP weapon any time soon. Of more importance is making the datalinks, radar, and weapons jam proof, for which you don't need EMP shielding. The PAF have been routinely rebuilding mirages, including complete rewiring, so not sure why you think this is beyond the capability of the PAF for JF-17.

I am not 'hung up' on anything. You are losing the plot here. Let us revisit my assertions:

I - The block 3 has undergone substantial upgrades which makes it infeasible to upgrade Block 1 and 2 to be exactly equivalent to Block 3.
II - An example of these upgrades is the installation of a fibre optic data bus.
III - This new data bus gives Block 3 capabilities that cannot be replicated easily in Block 1 and 2, an example being increased resistance to EMP attacks.

Now, you have made the following incorrect assertions regarding changes to FBW and data bus:

1. Free up internal space for the AESA - The AESA components are at the nose of the aircraft, whereas the physical connections of FBW databus run through the main body. This is completely irrelevant.
2. Improve mission computer performance - The interface between the silicon based mission computer and the fibre optic based data bus is a known point of bottleneck. The databus has nothing to do with the mission computer. What you are probably trying to say is the changes provide higher data rates.

Then there is the utterly amateurish assertion that since PAF can rewire the Mirage, it can replace copper wiring in Block 1 and 2 with fibre optics. First of all, let's be very clear - by spending enough money anything can be done. We need to look at what it takes to change copper wiring into fibre optic wiring.

Fibre optic is a very sensitive material that is prone to damage by a range of environmental factors such as temperature, vibrations, and humidity. This necessitates special cladding which changes the dimensions of the wiring when compared to copper. Throughout the length and breadth of the aircraft, space is allocated at design time in a very precise manner taking into account the dimensions of the wiring. This changes the entire internal mass distribution within the aircraft. This is what @araz referred to whom you rebuked with impertinence. There is a reason why Block 3 took years to finalize. It has undergone internal changes that take years to design, test and validate. Changing Block 1 and Block 2 to this configuration is not simply a matter of stripping out some wires and replacing them with new wires.

The comparison with the Kfir is completely relevant because it demonstrates the very real problems of changing an engine for any given airframe, particularly in terms of heat dissipation management. Coincidentally, IAI made no real changes to the intakes of the Mirage III for the Kfir. Again, the fin base intake on Block III is too small for any engine cooling.

First of all, let's do some approximate calculations. Let us approximate the opening on the base of the Block 3 tail by a circle which is 7 inches in diameter. This gives it a surface area of 0.087 sq ft (approx.) The diameter of RD-93 is 3.41 ft (using online calculator to convert mm to ft)

http://www.uecrus.com/eng/products/military_aviation/rd93/

which leads to a radius of 1.7 ft. Of this, let us discard 0.7 ft for the engine shaft and housing. Of this, let us assume an arc of 3 pi / 4 radians is actually exposed to incoming air on each side. This annular region has an area of (3 pi / 8) * ((1.7)^2 - 1) = 2.23 sq ft on each side of the engine. From the above link, the RD-93 has a bypass ratio of .49. If x is the surface area of the by pass air intake, and y is the surface area to the opening of the compressor, then x/y = 0.49 and x + y = 4.45, which gives y = 3 sq ft (approx) and x = 1.45 sq ft (approx). Note that I am probably over-simplifying a very complex engine geometry here. By this computation, the inlet at the base of tail comprises approx 6% of the by pass intake. At supersonic speeds, due to pressure variance, the air intake from the small opening can go up to 12% of the entire by-pass air flow. Does this seem like a small opening to you? Your amateurish brain cannot comprehend the apples to oranges nature of the comparison you are drawing with the Kfir.

So the Mirage III has enough internal space for an AESA, but earlier block JF-17s don't?! How did you come up with that conclusion?!

I merely said if someone wants to install an AESA radar, the Mirage has the internal volume. I did not specify which type of AESA (air cooled vs liquid cooled).

The Block I and II aircraft will not be getting an MLU any time soon, that's not what I claimed. The PAF have always hinted about the clear production and development path of the JF-17, with iterative block upgrades which can be applied to earlier airframes. Some time back, an early Block I JF-17 was sent to China for overhaul, as a pattern aircraft.

https://thediplomat.com/2019/05/china-overhauls-pakistan-air-force-jf-17-fighter-jet/

And the PAF has already setup a separate MRO facility for overhaul of JF-17, which can be used further down the road if they choose to apply an MLU type upgrade in the future.

https://www.janes.com/article/91686...rst-locally-overhauled-jf-17-thunder-aircraft

In addition, the JF-17 has been claimed to have an airframe life of around 4,000 hours, and as they are likely to be around for some time in PAF service, an "MLU" type extension of their lifetime isn't unrealistic, similar to what has been done with the Vipers. The same approach will be applied to Block II aircraft. The PAF likes to get as much life out of its assets as it can, this is amply demonstrated by the Mirages.

You need to justify why such an overhaul or MLU would make Block 1 and 2 exactly equivalent to Block 3. None of what you have written above is being disputed. Why are you going off on a tangential rant? And finally, your janes.com link is not even working. Did you copy/paste it from another website without checking?