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[FIXED] Viggen Ground Idle RPM


MBot

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I noted that at certain ambient temperatures, the ground idle RPM oscillates quite noticeably. In the mission attached, at an outside temperature of 30°C, the ground idle RPM oscillates between 51% and 52% about every other second. It might seem minor but from the engine sound is actually very apparent. Is this an expected behaviour of the engine?

Viggen_RPM.miz

Screen_170520_221530.thumb.jpg.9395a17404ce4c7cb00afeb8aa00e119.jpg

Screen_170520_221538.thumb.jpg.d8b0c947f06a745793461d60b2d12199.jpg

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it is, that's how the automatic fuel regelation (maybe it has another name) is doing it's job

 

Rather poorly if you ask me ;)

Hardware: VPForce Rhino, FSSB R3 Ultra, Virpil T-50CM, Hotas Warthog, Winwing F15EX, Slaw Rudder, GVL224 Trio Throttle, Thrustmaster MFDs, Saitek Trim wheel, Trackir 5, Quest Pro

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It depends on the outside temperature. Is it higher, it oscillates more, is the temp lower, no more oscillation...

 

And remember it a Swedish aircraft, constructed for the Swedish airspace...

30°C and we all are laying exhausted and unalive in the shades longing for the vitalizing winter :smilewink:

Helicopters and Viggen

DCS 1.5.7 and OpenBeta

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P9X79 Pro

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  • 1 month later...

I sill experience power fluctuations at ground idle despite fixes to Automatic Fuel Regulator in the last patch. Is this still being under development, or working as intended?

Hardware: VPForce Rhino, FSSB R3 Ultra, Virpil T-50CM, Hotas Warthog, Winwing F15EX, Slaw Rudder, GVL224 Trio Throttle, Thrustmaster MFDs, Saitek Trim wheel, Trackir 5, Quest Pro

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it is, that's how the automatic fuel regelation (maybe it has another name) is doing it's job

 

turn it to manual and you won't have any oscillation

 

Manual is Emergency only, Real life Viggen pilots never touched this switch.

 

I sill experience power fluctuations at ground idle despite fixes to Automatic Fuel Regulator in the last patch. Is this still being under development, or working as intended?

 

its working as intended. there is no reason to switch to manual, as soon as you go out of idle its vanished so i dont know where the problem is.

SFMBE



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Hence my question, is the fluctuation at idle a bug or not? I've never seen such behaviour in any other aircraft in the sim.

Hardware: VPForce Rhino, FSSB R3 Ultra, Virpil T-50CM, Hotas Warthog, Winwing F15EX, Slaw Rudder, GVL224 Trio Throttle, Thrustmaster MFDs, Saitek Trim wheel, Trackir 5, Quest Pro

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Hence my question, is the fluctuation at idle a bug or not? I've never seen such behaviour in any other aircraft in the sim.

 

It is bugged, Engine performance is very poor in automatic mode when you get some altitude

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Hence my question, is the fluctuation at idle a bug or not? I've never seen such behaviour in any other aircraft in the sim.

 

 

I could be wrong here, but i think the oscillating RPM is working as intended. an a RL behavior

SFMBE



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The idle RPM is a function of outside air temperature, there is a 3% band of allowed deviation.

 

55 to 58% at -40 to 0C

57 to 60% at 15C

59 to 62% at 30C

60.25 to 63.25 at 40C

This is while stationary at sea level.

 

Any deviation from this or RPM below 55% is possibly an indication of a bug.(Or you need to notify the ground crew to have it checked out)

 

I have seen no mention of rapid RPM fluctuations in the available documentation.

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  • 11 months later...

I'm 99% certain that it's a bug, idle RPM should never be below 55% at any temperature. In fact the fuel control seems to act in reverse by reducing the RPM instead of increasing it.

 

 

Here's a ground idle chart showing the allowed RPM.

 

XbvgplU.png

 

And allowed values for a MIL run-up.

 

HGSexB5.png


Edited by Vladinsky
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  • 3 weeks later...
  • 1 month later...
Is there a definite answer whether this RPM oscillation at ground idle is a bug or not? The engine sound is very apparent.

 

-IAtUmYjzVo

 

Outside air temperate is 30°C.

 

I have exactly the same bug, at 20 degrees the needles stay steady but the sound undulates, at 30 degrees sound and needles undulate in sync,

 

like in your video.

 

at 15degrees all is steady. So it seems that the ambient temperature here is the culprit.


Edited by <51>GRIZZLY
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