MBot Posted May 20, 2017 Share Posted May 20, 2017 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 Link to comment Share on other sites More sharing options...
razo+r Posted May 20, 2017 Share Posted May 20, 2017 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 Link to comment Share on other sites More sharing options...
some1 Posted May 21, 2017 Share Posted May 21, 2017 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: Virpil T-50CM, Hotas Warthog, Hotas Cougar, Slaw Rudder, Wheel Stand Pro, GVL224 Trio Throttle, Thrustmaster MFDs, Saitek Trim wheel, Trackir 5, Reverb Link to comment Share on other sites More sharing options...
razo+r Posted May 21, 2017 Share Posted May 21, 2017 Rather poorly if you ask me ;) It depends on the outside temperature. Is it higher, it oscillates more, is the temp lower, no more oscillation... Link to comment Share on other sites More sharing options...
Holton181 Posted May 21, 2017 Share Posted May 21, 2017 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 Win7 Pro 64bit i7-3820 3.60GHz P9X79 Pro 32GB GTX 670 2GB VG278H + a Dell PFT Lynx TrackIR 5 Link to comment Share on other sites More sharing options...
Vladinsky Posted May 21, 2017 Share Posted May 21, 2017 It's not expected, just another effect of the fuel regulator issues. Ground idle below 55% is not acceptable at any temperature. At 30C the expected value is ~59-62% Link to comment Share on other sites More sharing options...
some1 Posted July 17, 2017 Share Posted July 17, 2017 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: Virpil T-50CM, Hotas Warthog, Hotas Cougar, Slaw Rudder, Wheel Stand Pro, GVL224 Trio Throttle, Thrustmaster MFDs, Saitek Trim wheel, Trackir 5, Reverb Link to comment Share on other sites More sharing options...
whaaw Posted July 17, 2017 Share Posted July 17, 2017 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 Link to comment Share on other sites More sharing options...
some1 Posted July 17, 2017 Share Posted July 17, 2017 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: Virpil T-50CM, Hotas Warthog, Hotas Cougar, Slaw Rudder, Wheel Stand Pro, GVL224 Trio Throttle, Thrustmaster MFDs, Saitek Trim wheel, Trackir 5, Reverb Link to comment Share on other sites More sharing options...
addde Posted July 17, 2017 Share Posted July 17, 2017 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 Link to comment Share on other sites More sharing options...
whaaw Posted July 17, 2017 Share Posted July 17, 2017 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 Link to comment Share on other sites More sharing options...
Vladinsky Posted July 17, 2017 Share Posted July 17, 2017 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. Link to comment Share on other sites More sharing options...
MBot Posted July 14, 2018 Author Share Posted July 14, 2018 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. Link to comment Share on other sites More sharing options...
Vladinsky Posted July 15, 2018 Share Posted July 15, 2018 (edited) 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. And allowed values for a MIL run-up. Edited July 15, 2018 by Vladinsky Link to comment Share on other sites More sharing options...
SilverzRayleigh Posted August 2, 2018 Share Posted August 2, 2018 Has anyone figured anything out about this? Just bought the Viggen and Im getting ground Idle RPM issues as well. This exact bug/issue Link to comment Share on other sites More sharing options...
51GRIZZLY Posted September 6, 2018 Share Posted September 6, 2018 (edited) 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 September 6, 2018 by <51>GRIZZLY Link to comment Share on other sites More sharing options...
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