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What documentation was used to guide the creation of the JF-17 flight model?


Stackhouse

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Currently in a clean 1v1 BFM scenario the JF-17 is probably one of the most capable BFM aircraft in DCS. Surpassed by probably only the F/A-18C itself. The store page of the JF-17 indicates the following:

 

  • Nonlinear industry-level high fidelity 6DOF rigid-body flight model with real-life aerodynamic coefficients
  • Line-by-line recreated real-life full authority longitudinal fly-by-wire system and lateral/directional control augmentation system with various modes and control law reconstruction on malfunction.

 

This piqued interest because I can't seem to find any documentation to view or analyze it's capabilities on paper despite the above indication. Does anybody know of or have any documentation would've been used to accomplish that? Or any other documents that would normally serve as a guide when creating a flight model? Or perhaps what Deka used?

 

 


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2 hours ago, Gypsy 1-1 said:

You won't find anything on the JF-17 or its weapons because apparently these documents are not public and behind closed doors. The DCS JF-17 was also modelled after a fixed-base JF-17 sim used for training, with probably some generous system modelling. 

moreover, if the team is Chinese .... anyway it is the only module the alarm voices translated into English that sound ridiculously.

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On 3/24/2022 at 3:02 PM, LateNever said:

the only module the alarm voices translated into English that sound ridiculously.

I suppose some idiots can ridicule it, just like your post is ridiculous. However, a lot of people are drawn to and actually prefer the Betty in the Jeff.

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Surpassed by probably only the F/A-18C itself.

Well if you know what you’re doing in the F-15C or the F-14 you can give the JF-17 a hard time as well. There’s a point where both of these aircraft can keep lifting their nose up over the top while the Jeff can’t possibly follow and if you know how to exploit this against it it’s difficult for the Jeff to win. The Jeff’s acceleration is very exploitable. Even while clean the Jeff struggles accelerating out of low speed relative to other planes, and it’s not good at sustaining a vertical fight. The Mirage is capable of utilizing this same advantage against it, but the Jeff has a pretty significant rate advantage over the Mirage (on top of being able to mimic a lot of its maneuvers) so unless the Jeff pilot makes a major mistake it’s harder to consistently pull them into that situation compared to being in the Eagle or the Cat.

EDIT: In my experience flying the Jeff in BFM a lot of pilots seem to be caught off guard by its low speed nose authority and overlook or greatly overestimate its engine power. So they don’t think to take advantage of that weakness. It can pretend to be an F-18 but it can’t sustain it for as long as the F-18. It’s like an F-16/F-18 hybrid or imo more accurately an F-16/Mirage hybrid. It can mimic those planes, but don’t be fooled, it can’t recover as quickly as any of them.

Almost forgot, there’s another weakness that many people who don’t fly the JF-17 don’t realize. At around like 450+ knots the G-limiter severely hinders its turning capability and I find myself unable to keep up in a chase with most planes turning at these same speeds. I’ve yet to run into a pilot purposely exploiting this against me though, I think most just assume I’m intentionally sitting in deep lag pursuit. Turning off the FCS can help a little at these speeds but not much for some reason. All these planes would have to do is continue to threaten rating around me past these speeds and I would either have to slow down or take the vertical which opens up the opportunity for them to start taking advantage of that power/acceleration disadvantage I described earlier. I feel like there’s a lot of ignorance surrounding the JF-17 capabilities because a lot of people simply don’t fly the plane.


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5 hours ago, Javers said:

Well if you know what you’re doing in the F-15C or the F-14 you can give the JF-17 a hard time as well. There’s a point where both of these aircraft can keep lifting their nose up over the top while the Jeff can’t possibly follow and if you know how to exploit this against it it’s difficult for the Jeff to win. The Jeff’s acceleration is very exploitable. Even while clean the Jeff struggles accelerating out of low speed relative to other planes, and it’s not good at sustaining a vertical fight. The Mirage is capable of utilizing this same advantage against it, but the Jeff has a pretty significant rate advantage over the Mirage (on top of being able to mimic a lot of its maneuvers) so unless the Jeff pilot makes a major mistake it’s harder to consistently pull them into that situation compared to being in the Eagle or the Cat.

EDIT: In my experience flying the Jeff in BFM a lot of pilots seem to be caught off guard by its low speed nose authority and overlook or greatly overestimate its engine power. So they don’t think to take advantage of that weakness. It can pretend to be an F-18 but it can’t sustain it for as long as the F-18. It’s like an F-16/F-18 hybrid or imo more accurately an F-16/Mirage hybrid. It can mimic those planes, but don’t be fooled, it can’t recover as quickly as any of them.

Almost forgot, there’s another weakness that many people who don’t fly the JF-17 don’t realize. At around like 450+ knots the G-limiter severely hinders its turning capability and I find myself unable to keep up in a chase with most planes turning at these same speeds. I’ve yet to run into a pilot purposely exploiting this against me though, I think most just assume I’m intentionally sitting in deep lag pursuit. Turning off the FCS can help a little at these speeds but not much for some reason. All these planes would have to do is continue to threaten rating around me past these speeds and I would either have to slow down or take the vertical which opens up the opportunity for them to start taking advantage of that power/acceleration disadvantage I described earlier. I feel like there’s a lot of ignorance surrounding the JF-17 capabilities because a lot of people simply don’t fly the plane.

 

Exactly same thoughts as you 

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+1 for that analysis.

However... weaknesses as they may be, if you exploit them when flying the Jeff, you can turn them into benefits if used sparingly. Dissimilar combat requires that you use the entire flight envelope, and not a small sub-set because "that's what you're supposed to do".

It's idealistic (and IMHO straight-up deception) to suggest that you should always maintain max corner airspeed in a fight. You think the other guy is going to do that? That's how you end up dead (the naturally superior aircraft in such a situation will eventually win assuming fuel doesn't become an issue first). You must therefore break the deadlock.

If it's a fair fight, you already lost.

The AoA Limiter at higher speed is annoying but something that can be worked with. At some point the other guy is going to want to try and get behind you, and so will need to slow down to do that. You need to keep dragging them to the deck. Vertical fight works for defense if you're in the more powerful aircraft, but there are ways to defeat even this tactic in a lesser aircraft.

"Don't fly to them; let them fly to you".

I'm quite happy to bump the stall warning cue. There is a perfect example of flying at min flying speed in the Rafale vs. F-22 video. He's down at 85 kts at one point. 

 


Edited by Tiger-II
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"When performing a forced landing, fly the aircraft as far into the crash as possible." - Bob Hoover.

The JF-17 is not better than the F-16; it's different. It's how you fly that counts.

"An average aircraft with a skilled pilot, will out-perform the superior aircraft with an average pilot."

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The AoA Limiter at higher speed is annoying but something that can be worked with. At some point the other guy is going to want to try and get behind you, and so will need to slow down to do that. You need to keep dragging them to the deck. 

I think you may have misunderstood me a bit on this, and I figured some people would because it’s a pretty unique problem to this aircraft so that’s okay, but I could be wrong. I’m saying that past a certain speed the turn rate in the JF-17 is so restricted relative to certain planes that these other planes can out rate it by simply flying around at that exact same speed or higher. It’s that in combination with its slow acceleration that is an exploitable problem. There have been multiple instances where I’ve noticed the guy out in front of me gets scared and starts speeding up and as I pursue (I have no choice not to pursue and the reasons why should become clear later) we hit a point where I start locking up and he starts turning inside of my circle while extending away from me at the exact same time. I’m saying that he actually won’t need to slow down to get behind me.

If he’s turning inside my circle while flying at a higher speed that essentially means that if I maintain my speed trying to keep up with him and he maintains that high speed turn he will inevitably rate around behind me. So if you imagine us both flying on the deck in this situation that means I have two options. One of them is to slow down to the low 400-320 knots range so that I can turn again, but doing that gives the other guy a massive energy advantage in a plane that already has a significant power advantage over my JF-17. So now he can just take the vertical and if he knows how to smartly exploit the fact that I can’t regain energy quickly, not taking any unnecessary risks, then he can create a situation where he’s constantly taking positions that force me into a struggle for energy for the rest of the fight until he kills me because every defensive maneuver I make in response will cost me energy. 

My other option would be to take the vertical myself, but remember my opponent is at an equal or higher energy state as I’m doing this, while also being in a more powerful plane. So if he also takes the vertical, or even extends for more energy prior, then he’s once again going to be in a higher energy state than I am. If he knows how to exploit that in the same way I described above then the same exact situation plays out. It’ll take a bit longer because the initial energy difference won’t be as wide, but barring pilot error it’ll eventually produce the same result. 

But like I said I’ve yet to see a pilot purposely exploit this in a fight, because I don’t think they understand what’s happening to the Jeff. I think they think that I’m intentionally not pulling as hard as I can in the turn to follow them. Sometimes they’ll take the vertical and accidentally stumble on that path to draining my energy as described above, but this is entirely out of BFM instinct. They don’t actually recognize what caused the situation to happen. I know they don’t because they never attempt to force the situation again.

I absolutely do not strictly fly the corner speed of the Jeff in BFM, but there’s a time and a place for everything. Especially in a plane that can not accelerate and recover quickly.

 


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You would think people would exploit the high speed G limit since MiG-29/Flanker has similar high speed G limit for similar reasons. But their G limit is less aggressive and can be overridden, while only way to override it in JF-17 is EFCS, which you can only do at very high speed successfully, and you have to be careful to not over stress the aircraft. 
 

 

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Yeah exactly, those two aircraft have a similar issue. It can especially make things difficult in the MiG-29, but the Flanker can deal with it a bit better in my experience.

Like I said earlier I think this is a result of there not being many JF-17 pilots relative to other aircraft, especially in BFM. So, when people run into a good Jeff pilot in BFM it's typically their first time experiencing what the aircraft is actually capable of and the shock in combination with the ignorance creates the illusion that it's a lot more effective than it is. Not saying it isn't effective. It's a very capable BFM fighter if you know what you're doing, but part of that also requires that certain opponents do not entirely know what they're doing against it. It has a weakness so easily exploitable once you've acquired the knowledge that I think placing it directly behind the F/A-18 in BFM is a bit too far. I haven't even talked about the insane amount of lead required to hit with its gun. If it ever got an engine upgrade though it would probably be far more dangerous.

I've probably exposed too much. I should delete all of this. 👀


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The lead with the gun wouldn’t be so bad if we got a more modern software suite that had EEGS symbology. 

But even then, in a sustained high g turn you have to be almost point blank to be able to see the target over the nose…….

But yeah, people don’t see it’s weakness very much. I’ve been waiting since day one for someone to beat my by going transonic…..

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1 hour ago, AeriaGloria said:

The lead with the gun wouldn’t be so bad if we got a more modern software suite that had EEGS symbology.

Our current gun sight solutions should be far better than they are currently are. All of them still have this weird delayed reaction to ownship and target movents. Like compare how responsive the F-15's or MiG/Flanker LCOS, or even the Mirage's SS/LC are to the JF-17. I hope these eventually get updated to be actually useful in a fight.

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TO answer OP's question it's a combination of an aero pack from the RL sim (simplified in the form of less LUT breakpoints), a CFD study of LERX+main wing (publicly available), RD93 tech doc, reverse engineering of CL&CD from EM diagram, and FCS tech doc including a set of control block diagram. Every sources complement each other. The equation of motion is a standard 6DOF rigid-body dynamics that is widely used in the industry.

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EFM / FCS developer, Deka Ironwork Simulations.

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8 hours ago, LJQCN101 said:

TO answer OP's question it's a combination of an aero pack from the RL sim (simplified in the form of less LUT breakpoints), a CFD study of LERX+main wing (publicly available), RD93 tech doc, reverse engineering of CL&CD from EM diagram, and FCS tech doc including a set of control block diagram. Every sources complement each other. The equation of motion is a standard 6DOF rigid-body dynamics that is widely used in the industry.

Very interesting. What I have been most curious about is systems fidelity. I would assume that such systems knowledge comes from the real life manual and backed up by the real sim? 

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From what I understand of the systems and their heritage, they're very accurate. What do you think isn't accurate?

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"When performing a forced landing, fly the aircraft as far into the crash as possible." - Bob Hoover.

The JF-17 is not better than the F-16; it's different. It's how you fly that counts.

"An average aircraft with a skilled pilot, will out-perform the superior aircraft with an average pilot."

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On 3/28/2022 at 2:39 AM, LJQCN101 said:

TO answer OP's question it's a combination of an aero pack from the RL sim (simplified in the form of less LUT breakpoints), a CFD study of LERX+main wing (publicly available), RD93 tech doc, reverse engineering of CL&CD from EM diagram, and FCS tech doc including a set of control block diagram. Every sources complement each other. The equation of motion is a standard 6DOF rigid-body dynamics that is widely used in the industry.

Would you be able to point to the JF-17 EM diagram that was used?

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23 minutes ago, =52d= Skip said:

You think?

Reminds me of the one in the Herc (1:33, 2:57 & 5:04) and I love them both ...

 

Eh, sounded kinda weird at first but she grows on you. And Betty in Herc sounds a bit worse imho but still I wouldn't care as long as she saves my butt from fiery death or, even worse, embarrassment.

Also MAWS and Betty's "missile, missile, missile" saved me from heatseeker or two up my tailpipe so I can't complain

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The real TTS Betty is in special options as a selection, I believe “ENG 2” is the real one. So if you don’t like listening to Deka’s dev’s wife(ouch), you can switch to the real one and it’s sweet computer generated voice 

10 hours ago, Tiger-II said:

From what I understand of the systems and their heritage, they're very accurate. What do you think isn't accurate?

I think it’s very accurate to the degree that it’s possible for me an armchair laymen to guess. I just like learning about the creation of this module 

 

7 hours ago, Stackhouse said:

Would you be able to point to the JF-17 EM diagram that was used?

I doubt it is publically available. I think we have to trust ED in this, part of module verification is the 3rd party has to give ED the EM diagram so ED can verify how well it conforms to it.

I bet a resourceful consumer with tacview could probably do a good job generating their own EM diagram, and probably get within the 2-3% of the real one, as 2-3% is the ED standard for accuracy to technical charts 


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https://www.defenceview.in/chinese-j-10c-is-good-at-sneak-attacks-but-there-are-many-problems/
 

a senior Pakistani Air Force pilot who has flown a large number of aircraft claims the J-10c has better acceleration and climb then the JF-17 but worse then the F-16. It doesn’t say the version but it mentions he flew everything it Pakistan’s inventory which includes block 52 aircraft, Turkey’s which are GE powered and the UAE block 60. The block 50 is supposedly a little better then the block 52 in those categories.

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I would be extremely careful citing any sources from India; they have a very odd social media war going on with Pakistan, which somehow became a pissing match between the HAL Tejas and the JF-17.

 

Quick edit:

 

Just to clarify: I'm not saying Pakistani sources are good either. Both sides seem to tie the aircraft to nationalism and ego, so there are significantly skewed viewpoints printed on both sides, to the detriment of any realism presented in DCS. 


Edited by Foogle
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23 hours ago, Gypsy 1-1 said:

Yeah Indian source. Say over and over again over a dozen Chinese Airplane crashes in Pakistan in 18 months when almost all of them were J-7/A-5. Both sides like to be secretive about modern plane crashes. 

Their source for the radar being subpar is some Greece blog about how the JF-17 is a failure(hardly could be said to be a balanced or objective title), which in itself cites 0 sources but saying the radar is bad becuase Indian Planes did better on February 27th 2019. I don’t know if you think Indian planes did better, but that’s a very subjective fuzzy claim at best that no one can know for sure unless you were part of either counties armed forces. This incident is well documented to have spurred India to go to Russia to replace their short ranged R-77. The only confirmed Aerial victory of that engagement was a Pakistani F-16 shooting down an Indian MiG-21 Bison, hardly says anything about JF-17. This publication also claims that their new block III JF-17s are failures becuase they “look largely the same on the outside as previous versions.” And I think we all know that pictures rarely show operational capabilities that lie under the skin. 
 

And I’m not sure what any of this has to do with the creation of the JF-17 flight model in DCS, but I don’t trust a word of it 


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So the soothing 🤣 "Missile! Missile! Missile!" is actually the dev's wife and not the real voice?

She could make nuclear armageddon sound a fun day out.

Lucky dev! (and hello 'wife' if you're reading! 😄 ).

As for the JF-17 being rubbish - I recall some time ago citing sources that JF-17 fired several AA missiles in combat and scored a couple of kills???

I also showed that the missiles carried by the JF-17 are so good they're used as SAMs. They're reported to have over a 90% PK.


Edited by Tiger-II

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"When performing a forced landing, fly the aircraft as far into the crash as possible." - Bob Hoover.

The JF-17 is not better than the F-16; it's different. It's how you fly that counts.

"An average aircraft with a skilled pilot, will out-perform the superior aircraft with an average pilot."

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45 minutes ago, Tiger-II said:

So the soothing 🤣 "Missile! Missile! Missile!" is actually the dev's wife and not the real voice?

She could make nuclear armageddon sound a fun day out.

Lucky dev! (and hello 'wife' if you're reading! 😄 ).

As for the JF-17 being rubbish - I recall some time ago citing sources that JF-17 fired several AA missiles in combat and scored a couple of kills???

I also showed that the missiles carried by the JF-17 are so good they're used as SAMs. They're reported to have over a 90% PK.

 

I haven’t heard of PL-5 or PL-12/SD-10 being used as SAM. But I wouldn’t be surprised if PL-12 was eventually used like NASAM. The PL-10 used by the block III though I think is used in some SAM systems

AFAIK the only confirmed JF-17 kill is on an Iranian drone, PL-5 was used. You can see the marking on one, it seemed to be used as demo plane after the aerial victory. There are photoshops of people adding a Su-30 to it from the 2019 event, but it is almost certianly propaganda photoshop 
 

but this is getting a bit off topic 

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My other post was just talking about informational sources and how there are reports of JF-17 making a couple of kills. I have previously linked articles in older threads from a year or two ago when this was discussed.

Sky Dragon SD-10A SAM: http://chinesemilitaryreview.blogspot.com/2013/09/chinese-sd-10a-sky-dragon-medium-range.html

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"When performing a forced landing, fly the aircraft as far into the crash as possible." - Bob Hoover.

The JF-17 is not better than the F-16; it's different. It's how you fly that counts.

"An average aircraft with a skilled pilot, will out-perform the superior aircraft with an average pilot."

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