JF-17 Thunder Multirole Fighter [Thread 7]

[Bilal Khan (Quwa)]

Aren't the JIGS and procedure provided by CAC ? or are you implying that PAC is not following the proper procedures set forth to produce the modules / parts ?

At the end these are same folks that have kept the M-III/V flying for so long.

Also on side note, weren't the wings strengthen for B-III, could be the reason that Block-I & Block-II may have had wing structural issues due to loading ? I am just grasping for straws here though, as the saying goes ' too thin.'

I'm inquiring, not implying.

I want to know if PAC goofed at any point. We deserve to know because these institutions are supposed to be accountable to us.

 

[SQ8]

The last time JF-17 tried to go supersonic, It crashed. The wings couldnt handle it. THe very first crash of JF-17

That is a misnomer - that first crash was because they were supersonic and had equipment attached to the wings to measure performance for a local simulator. They overstressed the airframe trying transonic and supersonic turns which was not within OEM recommended stress regime.

Basically, PAC screwed up

 

[MIRauf]

I'm inquiring, not implying.

I want to know if PAC goofed at any point. We deserve to know because these institutions are supposed to be accountable to us.

Understood, thank you.

 

[Dazzler]

That is a misnomer - that first crash was because they were supersonic and had equipment attached to the wings to measure performance for a local simulator. They overstressed the airframe trying transonic and supersonic turns which was not within OEM recommended stress regime.

Basically, PAC screwed up

They grew overconfident after having pushed the aircraft to it's limits during previous sorties. Hence the crash. PAF has a habit of pushing their assets to the very limit of performance envelope.

Now they're pushing Dragons as hard as they can.

 

[White and Green with M/S]

I do not know if this is true or not.

These were deltas/Mirages not JF-17

 

[White and Green with M/S]

Still, The alumunium frame if put through extreme stresses gonna age real quick and show cracks as far as i know.

So does Mirages and our F-16 (older one) have same aluminum airframe, they can go supersonic but JF-17 can't, what a logic you have sir, I am sorry to say

 

[PakFactor]

Not me, what the hacked documents indians get their hands on 2 years ago as its a 2 year old news. Dumb Arses at PAC or Government still didnt fix their networks and got hacked once again in 2021 and 2022



Have you seen JF-17 going supersonic?



Still, The alumunium frame if put through extreme stresses gonna age real quick and show cracks as far as i know.

I swear to God we have *** retards in all levels and departments of government.

 

[Sinnerman108]

Yes. I remember a certain (unidentified) payload that was attempted to be integrated, caused wing fluttering and the crash.

Flutter exists due to either the wing's structural integrity issues ( less likely) or
it exists due to the control surfaces whacking out ( most likely).

So does Mirages and our F-16 (older one) have same aluminum airframe, they can go supersonic but JF-17 can't, what a logic you have sir, I am sorry to say

No it is not like that, the air-frame is an alloy, pure aluminum is too soft.
and as I have mentioned before the chances of the airframe structure restricting speed is unlikely; it's the control surfaces which are to be blamed mostly.

Aren't the JIGS and procedure provided by CAC ? or are you implying that PAC is not following the proper procedures set forth to produce the modules / parts ?

At the end these are same folks that have kept the M-III/V flying for so long.

Also on side note, weren't the wings strengthen for B-III, could be the reason that Block-I & Block-II may have had wing structural issues due to loading ? I am just grasping for straws here though, as the saying goes ' too thin.'

A Jig is only responsible for making sure the different parts of the fuselage are put together properly. It has nothing to do with making sure the aircraft will handle the load once it is built up right.

************************************************

So here goes, you can actually put the aircraft together and test the G limits ( which is in principle weight ) without it flying.
So for example if the wing spar structure are designed for handling 9G, that means 9 times the normal weight. This can be tested on ground.
What cannot be tested are the aerodynamic characteristics.
Tran-sonic - Supersonic and then back creates a whole new dimension both for the aircraft and the weapons. There is very little you can do except for trial and error and then building a huge knowledge base on those experiments.

Rest assured the JF-17 can do all the things you want it to , and there is nothing wrong with the design and engineering.

 

[Bratva]

+Pdf Think tank loool More like a drop tank.
No its a subsonic interceptor that's no good and can't do anything. PaF is stupid and you are the finest mind on here.

Have a nice day mate

You too mate. Thanks for being useless and having zero knowledge of fatigues aluminum alloy faces. Just to make you knowledgeable about what I'm talking about . Kindly go through this paper and then ponder over what caused the 17-246 and Dual seater crash in recent years

https://core.ac.uk/download/pdf/53034223.pdf

Some notable points

Fatigue crack initiation in aerospace aluminium alloy specimens

5.1 External or internal initiation Fatigue cracks in high-strength aerospace aluminium alloy specimens nearly always initiate at external surfaces.

This is the case even in gigacycle fatigue, where internal crack initiation is otherwise the rule for high strength steels and titanium and nickel alloys [14]. One practical exception is when the aluminium alloy surfaces have been shot-peened [15], see subsection 5.4.

5.2 Large inclusions Over the last 50 years there have been numerous investigations of fatigue crack initiation in highstrength aluminium alloys, e.g. Refs. [2, 9, 11, 16-24]. In some of the earlier work there was an understandable tendency to focus on crack initiation and development along slip bands [2, 9], and it was not recognised that fatigue cracks could initiate at large intermetallic particles (inclusions) unless they were already cracked [9]. However, further studies showed that fatigue cracks nucleate at both cracked and uncracked inclusions, and that these are the predominant sites of fatigue crack initiation in commercial alloys [16-18, 20-2]

@araz @SQ8 @Bilal Khan (Quwa) @Bilal. I guess above diagram can be an approximate diagram of what caused the first crash

Flutter exists due to either the wing's structural integrity issues ( less likely) or
it exists due to the control surfaces whacking out ( most likely).



No it is not like that, the air-frame is an alloy, pure aluminum is too soft.
and as I have mentioned before the chances of the airframe structure restricting speed is unlikely; it's the control surfaces which are to be blamed mostly.



A Jig is only responsible for making sure the different parts of the fuselage are put together properly. It has nothing to do with making sure the aircraft will handle the load once it is built up right.

************************************************

So here goes, you can actually put the aircraft together and test the G limits ( which is in principle weight ) without it flying.
So for example if the wing spar structure are designed for handling 9G, that means 9 times the normal weight. This can be tested on ground.
What cannot be tested are the aerodynamic characteristics.
Tran-sonic - Supersonic and then back creates a whole new dimension both for the aircraft and the weapons. There is very little you can do except for trial and error and then building a huge knowledge base on those experiments.

Rest assured the JF-17 can do all the things you want it to , and there is nothing wrong with the design and engineering.

Nicely explained. Isn't alumunium alloys are notorious for getting fatigued quickly over time when more stress is applied on them frequently? FIghter jets being one example. The research paper in my above post discusses the same thing

 

[Bratva]

That is a misnomer - that first crash was because they were supersonic and had equipment attached to the wings to measure performance for a local simulator. They overstressed the airframe trying transonic and supersonic turns which was not within OEM recommended stress regime.

Basically, PAC screwed up

I should have been more precise. Yes you are right. My point was Going supersonic will eventually put more stress on JF-17 airframe which has less composite materials, hence my educated guess, they wont fly it supersonic. As even Indians reported the crack issues JF-17 faced couple years ago.

 

[Sinnerman108]

Nicely explained. Isn't alumunium alloys are notorious for getting fatigued quickly over time when more stress is applied on them frequently? FIghter jets being one example. The research paper in my above post discusses the same thing

Yes and no,
Aluminium alloys are dominant in aviation, so they get all the mention.
Truth of the matter is that commercial civilian airliners also use aluminum alloys
and they do many many times more flight than fighters.

Metal fatigue is a very troublesome area to predict, and only trials and data help in determining some characteristics.

 

[Bratva]

They grew overconfident after having pushed the aircraft to it's limits during previous sorties. Hence the crash. PAF has a habit of pushing their assets to the very limit of performance envelope.

Now they're pushing Dragons as hard as they can.

If they are pushing aircrafts to its limits , then they should have on ground specialized support equipment sand skilled personnel who can inspect airframes minutely to detect if any cracks occurred on microscopic levels due to limits being pushed.

Overconfidence must not come at the cost of lack of support Which what caused the crash. Cuz they failed to inspect the craft after high stress applied on it and they continue to do so multiple times

Yes and no,
Aluminium alloys are dominant in aviation, so they get all the mention.
Truth of the matter is that commercial civilian airliners also use aluminum alloys
and they do many many times more flight than fighters.

Metal fatigue is a very troublesome area to predict, and only trials and data help in determining some characteristics.

But the Aircraft fly in a straight with zero High stress maneuvers with 99 % of time 1 or 2 G being applied on the aircraft during normal flying no?

While Fighter jet in each sortie normally has 3-5 G being applied on aircraft.

So Flying more frequently with Minimum G's vs Flying less with High G's everytime. The comparison would not be fair no?

 

[Sinnerman108]

But the Aircraft fly in a straight with zero High stress maneuvers with 99 % of time 1 or 2 G being applied on the aircraft during normal flying no?

While Fighter jet in each sortie normally has 3-5 G being applied on aircraft.

So Flying more frequently with Minimum G's vs Flying less with High G's everytime. The comparison would not be fair no?

The civilian airliners carry hell of a lot more load, and mind you they take as much beating as you can imagine; yet they have to maintain the highest safety record.
Imagine an airbus going through turbulance carrying 300 + passengers and cargo.

Point to be made here is that the amount of data available for the civilian airliners, and the number of flights they make is huge, and that allows engineers to design better.

If the same was available for military aircraft, they would do equally as good.

If i were you, I would concentrate on the speed difference of the aircraft. Remember it's the trans=sonic / sonic that is the problem.

 

[Bilal.]

@araz @SQ8 @Bilal Khan (Quwa) @Bilal. I guess above diagram can be an approximate diagram of what caused the first crash

And if you remember. The news was that the wing (root?) was strengthened.

 

[Two banks of the River]

Another problem was releasing weapons at high speed. Although the BVR was tested in China for release at 1.2 mach on another platform, other weapons like it's wvr, guided a2g bombs , c802 etc cannot be released at Supersonic speed.

If this is accurate, then it'd be worth knowing if PAC's responsible for the bulk of these issues (resulting from its production workshare). Sadly, we don't have a good enough CAG-type bureau in Pakistan to audit defence procurement. tbh I'm not surprised about the hacking. The industry's best cybersecurity people - and predators - are both "bloody civilians." So, it's no surprise that we're not benefitting from the best expertise.

The control system of RD33 family is extremely poor. RD33 licence production exists at HAL , still the servicing couldn't be improved for RD33MK problems. That is a major problem for low availability of any platform using this family of engines.