How to fire the GS-23? // RPM drops without firing - ED Forums
 


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Old 04-10-2020, 10:42 AM   #1
frumpy
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Default How to fire the GS-23? // RPM drops without firing

Hey there,


I don't get the rational on firing the internal gun of the ZA.
After takeoff,

RCtrl +3 for master arm,
LAlt+1/2 for launch & HUD
LShift + 0 to arm cannon
Explosive charge button
LShift+LCtrl+LAlt+A (Gun+GS, switch is moved even if cover is on)
LCtrl+Space


Then it does not fire, I think it should. After flying a bit around, suddenly the gun worked. After a bit more playing with the buttons (I don't remember which ones) the gun stopped working, but the RPM dropped when pressing the firebutton. What am I doing wrong?


p.s. the RPM drop can be replicated by
RCtrl +3
LAlt+1/2
LShift + 0
LCtrl+Space
Fire
Attached Files
File Type: trk l39za_rpm_decrease.trk (565.2 KB, 15 views)

Last edited by frumpy; 04-10-2020 at 11:09 AM.
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Old 04-10-2020, 11:25 AM   #2
-Martin-
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Hello,


In order to fire the gun you must have right speed (>400kph IAS) and right AOA (dive on a ground target should do). You will notice that AOA advisory lights up when you cannot fire the gun. It is designed that way so fumes are not ingested by the engine. For the same reason RPM drops automatically. It is a safety measure.


Btw, there is a button on the central piedestal to disable the limitter. It is for ground testing, but you may try to use it in the air to fire the gun under any speed and AOA.
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Last edited by -Martin-; 04-10-2020 at 11:28 AM.
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Old 04-10-2020, 11:28 AM   #3
paco2002
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That's correct, the RPMs Will drop automatically to avoid ingestions of fumes from the guns.
More RPMs = More possibilities to ingest fumes to the engine.
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Old 04-10-2020, 11:39 AM   #4
frumpy
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Thats good news! Seems like a bit of RTFM. Thanks guys!
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Old 04-11-2020, 04:26 AM   #5
Dehuman
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Quote:
Originally Posted by paco2002 View Post
That's correct, the RPMs Will drop automatically to avoid ingestions of fumes from the guns.
More RPMs = More possibilities to ingest fumes to the engine.
It will drop RPMs all the way down to nothing.
I can't see anything about this in the manual, I've always assumed it was a poorly implemented emulation of gas ingestion.
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Old 04-11-2020, 11:00 AM   #6
-Martin-
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Hello,

Quote:
Originally Posted by Dehuman View Post
It will drop RPMs all the way down to nothing.
I can't see anything about this in the manual, I've always assumed it was a poorly implemented emulation of gas ingestion.
p. 235 of the manual

Quote:
PT-12 engine overheat control system

The РТ-12 system for the L-39ZA has an additional function designed for decreasing fuel supply from the main fuel system while firing the gun. This precaution is made to prevent the gunpowder gases from getting into the inlet. The РТ-12 system starts operation when the gun firing mode is selected and the trigger button is pressed. Fuel supply decrease occurs the whole time when the trigger button is pressed; the engine speed can be decreased down to idle. After the trigger button is released, the speed returns to its previous value.
By the way, if you do not charge the gun and press the trigger, PT-12 will engage and decrease your RPM without the gun actually firing. This shows that it does not try to emulate gas ingestion; instead it behaves as intended.
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DCS needs AI bombers for all periods, and with working tailguns.
Modules: JF-17, Su-27, Su-33, L-39ZA/C, MiG-29A/S, MiG-21Bis, MiG-15Bis, KA-50, Mi-8MT, Bf-109K4;
Wish List: Mi-24P.
VPC T-50CM2+Varbrd Stick, CH Pro Throttle, CH Pro Pedals, TrackIR 5

Last edited by -Martin-; 04-11-2020 at 11:04 AM.
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