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[FIXED] Afterburner flameout


[PTF]Ali

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Hi there, I recently updated the DCS and noticed that finally Deka implemented afterburner flameout for RD-93 engine whenever you fire SD-10 and due to missile's smoke goes through intakes and then toward engine it flames out the afterburner for some seconds. But i was little concerned about accuracy of this feature.

 

After testing this feature for sometime i noticed that even if i'm launching SD-10 off-boresight (Cranking position), I'm getting the exact same afterburner flameout warning even though i saw missile smoke was not very visible near engine intakes or missile smoke could be hitting left or right side of the inlets.

 

I mean if left missile has been fired and smoke goes through just left or right intake then does it really physically flameout afterburner due to deficiency of oxygen going through engine? Or this feature is work in progress? Thanks.


Edited by uboats

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  • uboats changed the title to [CHK] Afterburner flameout
12 hours ago, Napillo said:

 I believe the flight computer does that so the missile smoke won't be ingested while in afterburner, I don't think it's because actual smoke goes in.


I believe system gives the engine warning because of RPM? It doesn't have anything related to flight computer there is no such thing exist on rd-93 right? Its an analogue engine. Engine has digital unit but it is not full authority device if it makes sense since engine has mechanical connection with the throttle. There is no F.A.D.E.C system available in jf-17 like other modern jets do have.


Edited by AliPG

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So after testing some indications what i'm getting after launching the SD-10s, i noticed these things happening after launching SD-10s.

 


Engine RPM goes down and Fuel efficiency went down for 5 seconds. And afterburner got cutoff for 5 seconds.
Fullscreen capture 9302021 91002 PM.bmp.jpg

 

I got no indication of any failure on pilot check list. 

Fullscreen capture 9302021 90938 PM.bmp.jpg

 

Only indications i am getting is Master warning blink for 1 and half second and A/B indicator light is going off for 5 seconds. You get no authority during 5 seconds on engines.

Untitled.jpg

 

Another thing which interested me is that on some angles there is no smoke at all touching the front inlets during missile operation, As well as smoke is not really the reason the engine is cutting off afterburner. Cause i went through the smoke of missile it didn't have any affect on engine. So it looks like there is some problem.

Fullscreen capture 9302021 12sddss2937 AM.jpg


Edited by AliPG

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Just like in the Mirage 2000 & L-39ZA the engine is set to idle automatically during firing by the aircraft systems.

The engine is not slowing down because of rocket exhaust ingestion, it's being pre-emptively slowed to prevent flameout /if/ rocket exhaust ingestion occurs.

There is no digital or smart controls on either of those aircraft/engines, so FADEC isnt required.


Edited by Foogle
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On 10/2/2021 at 10:45 PM, Foogle said:

Just like in the Mirage 2000 & L-39ZA the engine is set to idle automatically during firing by the aircraft systems.

The engine is not slowing down because of rocket exhaust ingestion, it's being pre-emptively slowed to prevent flameout /if/ rocket exhaust ingestion occurs.

There is no digital or smart controls on either of those aircraft/engines, so FADEC isnt required.

 


Yea that is why i reported, I'm firing SD-10 Off-boresight angle where no possible rocket exhaust was going through inlets. 

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4 hours ago, AliPG said:


Yea that is why i reported, I'm firing SD-10 Off-boresight angle where no possible rocket exhaust was going through inlets. 

I don't mean to be rude, but you actually need to read my post. 

 

The aircraft systems automatically reduce engine power during the firing sequence, whether or not it actually ingests the exhaust. 


Edited by Foogle
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On 10/8/2021 at 9:16 PM, Foogle said:

I don't mean to be rude, but you actually need to read my post. 

 

The aircraft systems automatically reduce engine power during the firing sequence, whether or not it actually ingests the exhaust. 

 


Honestly i don't mind, But jf17 engine is not that advance as you thinking lol, There is no FADEC device available here in Jf, There is literally mechanical connection with throttle. But mirage 2000 does have FADEC Device.


Edited by AliPG

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40 minutes ago, AliPG said:


Honestly i don't mind, But jf17 engine is not that advance as you thinking lol, There is no FADEC device available here in Jf, There is literally mechanical connection with throttle. But mirage 2000 does have FADEC Device.

 

The L-39 does the same thing, it doesn't need to be advanced to go to idle during firing.

You are massively overestimating the equipment required for setting the engine to idle.


Edited by Foogle
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1 hour ago, Foogle said:

The L-39 does the same thing, it doesn't need to be advanced to go to idle during firing.

You are massively overestimating the equipment required for setting the engine to idle.

 


So you are saying engine pre-planned itself before launching the missile, Or because of smoke, engine reacts to this as soon as possible? There is also warning when i'm launching SD-10. Some modern engines don't do that right? What is actual factor here? Is there any button to disable this feature?


Edited by AliPG

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1.

 

On 10/10/2021 at 7:58 PM, AliPG said:

So you are saying engine pre-planned itself before launching the missile, Or because of smoke, engine reacts to this as soon as possible?

 

Foogle already answered your question

 

On 10/8/2021 at 5:16 PM, Foogle said:

The aircraft systems automatically reduce engine power during the firing sequence

 

2.

 

On 10/10/2021 at 6:02 PM, AliPG said:

There is literally mechanical connection with throttle.

 

Jet engines are more complex than a mechanical lever connected to fuel pump, when you move the throttle, you are actually moving a lever on the engine governor i.e. for 100% rpm/thrust.

 

What this means for fuel delivery, etc. from the governor depends on

 

• air temperature

• air pressure

• current rpm

• etc. (i.e. I'm likely forgetting a few factors)

 

The engine has various sensors fitted to measure these and "govern" it's speed i.e. when the pilot moves the "throttle" lever to 100%, RPM increases to 100% and holds steady, (i.e. the engine doesn't overspeed and destroy itself like most cars would if give full throttle while out of gear).

 

I'm not sure on the conditions required for the JF-17's weapon system to reduce engine RPM to idle but IIRC in the L-39 they would be

 

• Weapon System ARMED

• Cannon selected

• Speed Above 310 km/h (req'ed to fire the cannon)

 

... and when all  3 conditions are meet, the RPM will drop to idle when the Trigger is DEPRESSED.

 

Comment

I'm a little surprised the JF-17 reduces engine RPM when firing wing tip SD-10's but perhaps it's a disadvantage of mixing an older engine system with a modern weapons computer (i.e. it can't can't be hard wired for a particular weapon type/station) or is just another of the JF-17's "peculiarities". 

 

 

   


Edited by Ramsay
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On 10/12/2021 at 4:53 PM, Ramsay said:

1.

 

 

Foogle already answered your question

 

 

2.

 

 

Jet engines are more complex than a mechanical lever connected to fuel pump, when you move the throttle, you are actually moving a lever on the engine governor i.e. for 100% rpm/thrust.

 

What this means for fuel delivery, etc. from the governor depends on

 

• air temperature

• air pressure

• current rpm

• etc. (i.e. I'm likely forgetting a few factors)

 

The engine has various sensors fitted to measure these and "govern" it's speed i.e. when the pilot moves the "throttle" lever to 100%, RPM increases to 100% and holds steady, (i.e. the engine doesn't overspeed and destroy itself like most cars would if give full throttle while out of gear).

 

I'm not sure on the conditions required for the JF-17's weapon system to reduce engine RPM to idle but IIRC in the L-39 they would be

 

• Weapon System ARMED

• Cannon selected

• Speed Above 310 km/h (req'ed to fire the cannon)

 

... and when all  3 conditions are meet, the RPM will drop to idle when the Trigger is DEPRESSED.

 

Comment

I'm a little surprised the JF-17 reduces engine RPM when firing wing tip SD-10's but perhaps it's a disadvantage of mixing an older engine system with a modern weapons computer (i.e. it can't can't be hard wired for a particular weapon type/station) or is just another of the JF-17's "peculiarities". 

 

 

   

 


Good review, So if this system is automatic then there is no way to turn off this feature or override this anyway?

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On 10/12/2021 at 4:53 PM, Ramsay said:

Comment

I'm a little surprised the JF-17 reduces engine RPM when firing wing tip SD-10's but perhaps it's a disadvantage of mixing an older engine system with a modern weapons computer (i.e. it can't can't be hard wired for a particular weapon type/station) or is just another of the JF-17's "peculiarities". 

 

Ummmm, I'm assuming this feature must be for safety reason, If french mirage2000 has the same issue then that would be a common thing in 4th generation jet, However there were many problems during creation of Jf-17, I would not say sanctions were the reason but if you look at augmentation and light fighter doctrine then with respect to logistic operations during war, I mean the availability of certain airframe parts all together, Jf-17 was born to overcome these problems. Its an open platform available for all military tech companies in the world as well as for developing nations. But despite after all it is a light fighter jet and it checks all requirements which airforce need.

I made this post because i had question in my mind, If mig29 doesn't do the same thing then there are many question marks regarding early access JF-17. This must be a active feature for RD-93 engine if not passive. Mig29 doesn't shut down engine operation during Fox1 engagement. And yes Jf-17 has Mig29 engine if it makes sense.

New block-3 JF-17 going to get RD-93MA version which is specially optimized for single engine operations.  But specifically we don't know what block JF-17 is in DCS? I still doubt this is a safety feature for making fighter more reliable during combat? I don't mind this but there must be a override setting similar to EFCS switch which lets Jf-17 pull 8+ Gs during supersonic flight then if it has Digital control device or something like that related to engine haha 😃


Edited by AliPG

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  • uboats changed the title to [FIXED] Afterburner flameout
4 hours ago, [PTF]Ali said:

@uboats Hi there, Thanks for the update. Would you guys mention what you have fixed so far. What really was the case here?

 

The fix is for the false detection of missile trails.

There is an anti-surge system in the JF-17, but is not fully implemented yet. Currently it will only detect a surge and counteract it by interrupting fuel flow for up to 3 sec. There's an anti-surge switch so that you can turn off the system.

When firing cannons or missiles, the system should activate.

The Mig-29 has a very much same system which I don't think is implemented in DCS. In addition to the anti-surge function that JF-17 has, the Mig-29 can also close it's intake ramp for an additional 10% maximum.


Edited by LJQCN101

EFM / FCS developer, Deka Ironwork Simulations.

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8 hours ago, LJQCN101 said:

The fix is for the false detection of missile trails.

There is an anti-surge system in the JF-17, but is not fully implemented yet. Currently it will only detect a surge and counteract it by interrupting fuel flow for up to 3 sec. There's an anti-surge switch so that you can turn off the system.

When firing cannons or missiles, the system should activate.

The Mig-29 has a very much same system which I don't think is implemented in DCS. In addition to the anti-surge function that JF-17 has, the Mig-29 can also close it's intake ramp for an additional 10% maximum.

 

Hi, Thanks for the update, that is really interesting honestly. The reason behind i tried to get to this specific feature was operational requirement at high mach numbers and high altitude where you have to charge offensive with formation. I have been testing JF-17 with Sd-10s capability with respect to formation engagements. We disqualify JF-17 in our formation only because of that issue and we replaced it with f-16 where Jf17s were not able to perform certain task and tactics. I hope we will see fully operational anti-surge system anytime soon. Good luck guys.


Edited by [PTF]Ali

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