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JF-17 Thunder Multirole Fighter [Thread 3]

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I think you have the wrong context of 'redundant'...


I am willing to guess that for the pitch axis, which is a pure fly-by-wire axis, the pitch axis is quad redundant. For the roll and yaw axis, since they are mechanical-hydraulics, their commands would be augmented by triple-redundant electrical signals, hence the phrasing 'dual redundancy'.


Not for pitch.


For any fly-by-wire axis, there is no turning 'off' the system. Unless you call a crash a 'turn off' switch.

dual or quad, i don't know what is the status now. so, you can guess whatever you want. no one will certified it even if they do know.

in the 1990s, i can't remember the exact year, a SU-27 pilot did turn off the AC's FBW and take it home. but for J-10 or F-16, you are right. their FBW can only be switch off, otherwise they will fall and clash.

oh, one more thing to add. when i said turn off, i mean the mission computers or softwares only, not the entire controling system. all the fins will return to the default position if the mission computer is down. that is why static instable planes can not turn off their FBW, default position of the fins, in most cases, means falling.
 
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dual or quad, i don't know what is the status now. so, you can guess whatever you want. no one will certified it even if they do know.

in the 1990s, i can't remember the exact year, a SU-27 pilot did turn off the AC's FBW and take it home. but for J-10 or F-16, you are right. their FBW can only be switch off, otherwise they will fall and clash.
Without more details, I cannot give a better speculation, but I will use the old F-111 as an example. The F-111's flight control system is a mechanical-hydraulics system augmented by a triple-redundant electrical system. When the system is working normally, pilot stick commands, via a transducer, is compared against INITIAL aircraft response, which is detected by the gyros and accelerometers, and the FLCS computer will either reduce or increase the 'move' signal to the hydraulic actuators. The loop is seamless enough that no one will feel anything other than a smooth response by the aircraft. In an emergency, the pilot could turn off all three axis electrical inputs and fly the aircraft purely on his own reflexes, from stick commands to the hydraulics.

If the SU-27's FLCS is similar, then yes...the pilot could turn off the electrical augmentation system, or stability augmentation, and fly home on his own reflexes. Bet the guy had a long good rest aided by a lot of vodka. Any pilot in that situation and made it home deserve the reward.
 
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x_man,

Thanks for elaborating on this unique aspect that most of the members missed here.

I have a question about J-10s performance. Right now 4 of them have crashed and I imagine only 20s of those would be in the Chinese air-force by now. What do you think about performance of J-10s and how much weight can we put on this aircraft for the National Defense?

there have been 4 incidents known for now involving J-10, 3 resulting aircraft crashes and 1 incident where the aircraft was landed safely.

One was a prototype, lost due to failure of the FBW system, rest had most probably engine problem, and the one which landed safely had some avionics problem due to engine smoke escaping into the cockpit. Thus technically, only 2 crashes due to its engines, which isn't a bad figure looking at its years in service and the numbers so far built.

200+ is the figure quoted so far of the J-10s put in service.

And with PAF participation in the FC-20 development, we can further make it a potent platform and it can fulfill the task as a front line fighter quiet effectively.
 
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Without more details, I cannot give a better speculation, but I will use the old F-111 as an example. The F-111's flight control system is a mechanical-hydraulics system augmented by a triple-redundant electrical system. When the system is working normally, pilot stick commands, via a transducer, is compared against INITIAL aircraft response, which is detected by the gyros and accelerometers, and the FLCS computer will either reduce or increase the 'move' signal to the hydraulic actuators. The loop is seamless enough that no one will feel anything other than a smooth response by the aircraft. In an emergency, the pilot could turn off all three axis electrical inputs and fly the aircraft purely on his own reflexes, from stick commands to the hydraulics.

If the SU-27's FLCS is similar, then yes...the pilot could turn off the electrical augmentation system, or stability augmentation, and fly home on his own reflexes. Bet the guy had a long good rest aided by a lot of vodka. Any pilot in that situation and made it home deserve the reward.

Chinese pilots are not in favour of vodka.

i think i know why you always believe that FBW system can be turn off. you have a USAF mind set, most of the F15,16,18,22s are controledy 100% digital FLCS. however, the russians' don't. they kept the mechanical-hydraulics system too. actually, if a SU-27 or 30 want to do a Cobra, the first thing it's pilot would do is to turn off the FBW system.
 
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@Gambit

Could you please expand on the topic of an aircraft firing its BVRAAM and letting the AWAC guide the BVRAAM into the enemy aircraft. A lot of members over here are at disbelief with this information, i remember you gave your input on this topic but that was long long time ago. So its highly appreciated if you could expand on this topic.

Thanks in Advance
 
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i think i know why you always believe that FBW system can be turn off.
No...I do not. I said that if the FLCS is completely fly-by-wire, there is not 'off' switch or mode. It is not possible. You have a reading comprehension problem.

you have a USAF mind set,
No idea what that means.

most of the F15,16,18,22s are controledy 100% digital FLCS.
Wrong...The F-15's FLCS is a mechanical-hydraulics augmented by a triple redundant electrical system. This combination has proven to be combat reliable. The other aircrafts are true FBW systems.

however, the russians' don't. they kept the mechanical-hydraulics system too.
Too bad for them.

...actually, if a SU-27 or 30 want to do a Cobra, the first thing it's pilot would do is to turn off the FBW system.
The Cobra is a nearly useless maneuver against today's fighters. And John Boyd did such a maneuver in an F-100 long before the Russians claimed they did it.
 
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No...I do not. I said that if the FLCS is completely fly-by-wire, there is not 'off' switch or mode. It is not possible. You have a reading comprehension problem.

this is a USAF mindset, the USAF's FBW can not be turn off or what you said "no off mode" doesn't means all the FBW can't. and what is a "completely fly-by-wire"? a SU-27 is completely fly-by-wire too, it just has one more reduntdent control system.

Wrong...The F-15's FLCS is a mechanical-hydraulics augmented by a triple redundant electrical system. This combination has proven to be combat reliable. The other aircrafts are true FBW systems.


Too bad for them.

to bad for them, and reliable for F-15 ?

The Cobra is a nearly useless maneuver against today's fighters. And John Boyd did such a maneuver in an F-100 long before the Russians claimed they did it.

well, if the SUs have lost too much speed, at least they could do a Cobra to evade one more missile. F100 did it first? no idea and doesn't care.
 
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@Gambit

Could you please expand on the topic of an aircraft firing its BVRAAM and letting the AWAC guide the BVRAAM into the enemy aircraft. A lot of members over here are at disbelief with this information, i remember you gave your input on this topic but that was long long time ago. So its highly appreciated if you could expand on this topic.

Thanks in Advance
Here is the initial understanding of how radar guidance works for air-air missiles...





There are two distinct units inside a radar set: transmitter and receiver. Each can be physically distinct as well instead of cohabitation inside a single container, or line-replaceable-unit (LRU). For sem-active guidance, the missile is the receiver part of radar detection. The parent aircraft is the transmitter part.

For active guidance, the missile is fed initial general target information: direction and distance. The missile will prepare its own complete radar system to search for a target in that sector. Keep in mind that a missile's nosecone is space limited so the missile's radar antenna does not have a lot of room, or physical scan limit, to perform its search.



Plus...Target information is highly dependent upon antenna physical dimension. The larger the antenna, the tighter its beam and the better the target resolution. On the other hand, to compensate for small antennas, higher freqs can be used to produce pencil beams but at the expense of maximum effective detection range. This means even for active radar guided missiles, air-air or ground-air, it is best for a larger radar system to provide the missile with target information for as long as possible. Even for 'fire-and-forget' type. The joke is that you can forget about the missile hitting the target if you do not provide target information for up to %30 of the missile's flight time. Of course, the closer you are to the target, the less need of you, the parent aircraft, to provide that illumination.

So the next logical evolution of active radar guided missiles is on how to provide that EXTERNAL guidance until the missile's own radar is capable of taking over within that 'no escape' zone for the target. That external guidance could be the parent aircraft or an AWACS. The form of guidance could be radar, as in target illumination, or the AWACS tracks both target and missile and sends course correction information to the missile. The AWACS does not -- does not -- have control of the missile. The AWACS simply performs the standard triangulation calculations between itself, the missile and the target and if there are any heading deviation between missile and target, the AWACS will sort of 'advise' the missile to alter its course. The missile, being robotic, will of course obey. All the while still searching for the target with its own radar.

A more sophisticated missile will have its radar off until its distance to target is less than %50 from the original calculation. The AWACS will provide that distance figure. Then when it turn its own radar to illuminate the target, it will have the target within that 'no escape' zone. That is why today pilots can no longer ignore AWACS transmissions whereas in the past they can go on with their mission. Even more sophisticated missiles will be able to accept 'hand-off' signals, meaning it is 'advised' to accept guidance information from another airborne platform such as another fighter or another AWACS from a different direction or even ground controllers. More sophisticated missiles will be able to tell everyone in the vicinity that it is tracking the target based upon their distinct radar illuminations of the target, thereby requiring no guidance at all. The more the target is illuminated from different directions, the sooner the target will be in that 'no escape' zone.

This is not science fiction. The problem have always been miniaturization of the radar components. So the smaller the components, the greater the capabilities and performance levels of those capabilities. The move from semi-active to active guidance testified to that fact.
 
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Can any body tell me

how much jf-17 are manufactured in pakistan?

and the 14 inducted into service or they all were made locally in pakistan>?
 
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this is a USAF mindset, the USAF's FBW can not be turn off or what you said "no off mode" doesn't means all the FBW can't. and what is a "completely fly-by-wire"? a SU-27 is completely fly-by-wire too, it just has one more reduntdent control system.
If the SU-27 has a mechanical-hydraulics part of its FLCS, then it does NOT have a true fly-by-wire FLCS. Therefore the pilot can turn off the electrical inputs and fly the aircraft himself. The electrical part is for stability augmentation, command or else. For any FLCS that does NOT have that mechanical-hydraulics side, then it is a true fly-by-wire FLCS and there is no turning anything 'OFF'. Popular media do not inform the readers of the fact that both sides, mechanical-hydraulics and electrical, works together. It is a gross misconception that the mechanical-hydraulics side is the 'back-up' FLCS.

to bad for them, and reliable for F-15 ?
Quite reliable. A mechanical-hydraulics system augmented by a triple redundant electrical system is proven reliable since the 1950s.

well, if the SUs have lost too much speed, at least they could do a Cobra to evade one more missile.
To do that Cobra maneuver, the SU-27 has to reduce speed.

F100 did it first? no idea and doesn't care.
No Russians care that they lied about who did it first.
 
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If the SU-27 has a mechanical-hydraulics part of its FLCS, then it does NOT have a true fly-by-wire FLCS. Therefore the pilot can turn off the electrical inputs and fly the aircraft himself. The electrical part is for stability augmentation, command or else. For any FLCS that does NOT have that mechanical-hydraulics side, then it is a true fly-by-wire FLCS and there is no turning anything 'OFF'. Popular media do not inform the readers of the fact that both sides, mechanical-hydraulics and electrical, works together. It is a gross misconception that the mechanical-hydraulics side is the 'back-up' FLCS.

completely, true or whatever, you said they aren't but they said they are. guess what? you have your defination they got theirs.

Quite reliable. A mechanical-hydraulics system augmented by a triple redundant electrical system is proven reliable since the 1950s.
i didn't question that, that's not my point... but never mind.

To do that Cobra maneuver, the SU-27 has to reduce speed.

do it, you lost speed; but do not, you lost the plane. so, it's not "nearly useless", right.
 
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completely, true or whatever, you said they aren't but they said they are. guess what? you have your defination they got theirs.
And 'they'...whoever 'they' are...are wrong.
 
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all money spent on making jf17 could have been better spent on getting full tot for j10 and make it the workhorse of paf.
but..no we have to make fighter jets even if we are cash strapped.
 
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all money spent on making jf17 could have been better spent on getting full tot for j10 and make it the workhorse of paf.
but..no we have to make fighter jets even if we are cash strapped.

J-10 and jf-17 II will be mostly similar
We will get 50% profit on the export of each jf-17..
only 250Mn USD are spented on jf-17 and we hav a good multirole fighter..
 
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