Engine idle regime at minimun throttle
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I think I am having a too high idle engine regime with throttle at minimun. .- As a consequence, I noticed that when taxing at idling regime, speed grows fast and the F16 needs to brake constantly.-
The RPM meter shows betwen 75 and 80 %, is that normal ?
I recalibrated my TM Cougar several times at the Hotas Cougar Control Panel.-
I read that it normally happens, but in my case I think it is out of standard parameters -
I had that same problem a while back…it drove me crazy (lots of hard landings). I don’t have a Cougar system, but I messed around with setting the deadzones on my X52 Pro and it fixed the problem. I don’t like having the lessened throttle range of movement, but idle stays at idle now. I hope this helps!
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Highly doubt this is a dead zone issue as much as a mis-configured throttle in BMS. You should have a red line in the BMS controller config on the throttle line towards the bottom and it should match the blue bar showing current throttle setting when you have it set to minimum so that BMS knows that is where the minimum throttle setting is at. If you set idle on your throttle and in the BMS config the red line is still below the blue bar at that setting that is exactly why you are seeing RPMs that high on the ground. It should be more like 68-70% at idle on the ground.
Clicking on advanced search and entering “throttle config” the second search entry from the top would have given you the answers to how this is done in BMS.
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BMS should be at 70%. IRL the idle power varies with quite a few factors, but should still be between 62% and 80% at idle.
For ground operations:
Since the DEC maintains constant idle thrust and minimum bleed air pressure, rpm varies with temperature and pressure altitude (higher temperature or pressure altitude results in higher rpm). While VSV reset is active, idle rpm is 2-3 percent higher than normal. During cold weather operations below 30°F, the DEC logic, when either commanded manually or automatically, increases anti-ice bleed air pressure to improve system performance at idle rpm. Engine rpm may increase as much as 3 percent during anti-ice operations.
Note that the higher RPM due to higher temperature and pressure altitude does NOT result in higher thrust.
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Having flown bms with 2 RL viper pilots, and depending on the load out, I quote: “the jet’s taxi at idle continues to increase, at 25 ground speed we brake back down to 15, rinse & repeat until hold-short/parked”
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BMS Manuals note that the Viper will move under idle thrust. You have to cover the brakes.
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Highly doubt this is a dead zone issue as much as a mis-configured throttle in BMS. You should have a red line in the BMS controller config on the throttle line towards the bottom and it should match the blue bar showing current throttle setting when you have it set to minimum so that BMS knows that is where the minimum throttle setting is at. If you set idle on your throttle and in the BMS config the red line is still below the blue bar at that setting that is exactly why you are seeing RPMs that high on the ground. It should be more like 68-70% at idle on the ground.
Clicking on advanced search and entering “throttle config” the second search entry from the top would have given you the answers to how this is done in BMS.
Thanks, I fixed the problem as you said, now idle is at 70%,-
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do note that other factors can affect the idle setting. For instance, there is ground idle, approach idle, and in-flight idle. And above mach 1.1, the engine will not ‘idle’ either, but run at much higher RPM.
Take note that engine characteristics depend on the specific engine (and thus, specific block of F-16). This is taken from the F110-GE-129 section of a CM manual:
Regardless of temperature, stabilized NOZ POS indicator indications should not exceed 15 percent open in MIL.
Engine operation is continually optimized as flight conditions change. This is evident by slight changes in the NOZ POS, RPM, and FTIT indicator indications.
As altitude increases, idle rpm increases in order to maintain the required bleed air pressure for satisfactory ECS operation and stall margin for the engine. As a result, rpm and FTIT response during throttle movement between low throttle settings is significantly reduced.
At 1.4 mach and greater, the minimum thrust level is near MIL even though the throttle may be retarded below MIL. Typically, the minimum thrust level decreases with mach number between 1.4-1.1 mach. At IDLE and while decelerating through 1.1 mach, the engine decelerates to normal inflight idle thrust.
Reduced speed excursion (RSE) logic is activated during engine deceleration to idle speed above 0.6 mach. RSE results in a higher in-flight idle rpm offset by a greater nozzle opening than normal in-flight idle.
Idle thrust changes from in-flight idle to approach idle between 0.6-0.5 mach, resulting in an engine rpm change of approximately 10 percent. Slightly more time is required to accelerate the engine from approach idle thrust when airspeed is below 0.5 mach.
Idle thrust changes from approach idle to ground idle between 80-90 knots and results in reduced engine rpm of approximately 2 percent. This change occurs during the landing roll to achieve desired ground idle thrust levels for taxi.
While VSV reset is active, idle rpm is 2-3 percent higher than normal.
A high frequency vibration may be felt through the cockpit floor, ejection seat, and/or rudder pedals as a result of aircraft structural response to normal engine operation. The vibration is most noticeable with the aircraft in a clean configuration with reduced fuel loads at lower airspeeds when the engine is operating near MIL thrust or above. This vibration has no adverse effect on the engine or aircraft.
The GE-100 in contrast does not have an approach idle setting.
I wonder if the engine logic is modelled in BMS? Guess Ive got something to try this evening
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Of course it is
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I meant between different engines - so GE-100 in BMS is different logic to GE-129?
This is very cool
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I meant between different engines - so GE-100 in BMS is different logic to GE-129?
This is very cool
yes they are different, but not on every aspect, as in real :
for isntance
GE 100 MIL RPM is 1.03 while GE 129 is 1.08
max AB RPM : 1.04 vs 1.08
spoolrates are different
FTIT are different (not sure in 4.33 though…)
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…we’re not talking % RPM here, right? But limiting Mach?
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We are talking about engine logic in general and yes different engines are modeled In those areas
Rpm , nozzle posit , ftit , spool times etc….
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I know that some engines have a speed lockup which happens in conjunction with Mach (some GE engines being of that case). Sometimes that’s also influenced by the inlet…so it can vary from model to model even for the same engine. I’ll consult the Dash 1.
But still - “1.03” what?
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I know that some engines have a speed lockup which happens in conjunction with Mach (some GE engines being of that case). Sometimes that’s also influenced by the inlet…so it can vary from model to model even for the same engine. I’ll consult the Dash 1.
But still - “1.03” what?
Guessing he is talking about max RPM. 103% and 108%
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Knowing what I do about the F110, that doesn’t quite make sense…that engine isn’t allowed to over-speed. At least it wasn’t as I knew the GE engine back in the mid 80s…but that was a long time ago, in another of my lives.
But it would make sense that it has a speed limiter of some sort - fan speed, I think. Plus I’ve never heard rotor speeds expressed that way…always only as numbers like 000.0%. The Dash 1 says the Pratt engine is limited to 97% steady state and 98% transient; and the GE to 108% steady state, and 109% transient. Which is still odd to me, but that’s what the book says…and I’d expect them to lock to those numbers in certain circumstances - generally driven by Mach/inlet recovery/flow limitations. Which is what it sounds more to me like what BMS is modeling.
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Knowing what I do about the F110, that doesn’t quite make sense…that engine isn’t allowed to over-speed. At least it wasn’t as I knew the GE engine back in the mid 80s…but that was a long time ago, in another of my lives.
But it would make sense that it has a speed limiter of some sort - fan speed, I think. Plus I’ve never heard rotor speeds expressed that way…always only as numbers like 000.0%. The Dash 1 says the Pratt engine is limited to 97% steady state and 98% transient; and the GE to 108% steady state, and 109% transient. Which is still odd to me, but that’s what the book says…and I’d expect them to lock to those numbers in certain circumstances - generally driven by Mach/inlet recovery/flow limitations. Which is what it sounds more to me like what BMS is modeling.
What does 100% mean ? This is just a matter of norm !
And all our data have been cross checked zillions time
Be aware that in real rmp is evolving around a value , and is different from engine to engine (even with the same engine type) and with external condition . This is not modeled
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Hi guys!
Since we are talking about F-16 engines … I would need to know what are the specific REAL LIFE “standard” following values for the our simulated F-16 engines:
FTIT Start (normal/common T° peak on engine start)
FTIT Idle (normal/common T° at idle)
FTIT Max (normal/common T° full dry)
FTIT AB (normal/common T° full AB)For the following engines:
In priority I need:
F110-GE-100
F100-PW-200
F100-PW-220Additionally (because I already received recommendations/references for those, but with more I could cross check)
F110-GE-129
F100-PW-229…
Note: I am NOT asking the values shown in the REAL Dash-1 (nor in BMS -1 but the one published in any other REAL engine technical documentation or the one shown in REAL fight! In -1, there are only the limitations, but normal ops values are below those maximum acceptable values. What I need are the generally observed common/normal values.
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If you are after the FTIT values BMS produces, I can do a quick test run presently for you…?
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Hi guys!
Since we are talking about F-16 engines … I would need to know what are the specific “standard” following values for the our simulated F-16 engines:
FTIT Start (normal/common T° peak on engine start)
FTIT Idle (normal/common T° at idle)
FTIT Max (normal/common T° full dry)
FTIT AB (normal/common T° full AB)For the following engines:
In priority I need:
F110-GE-100
F110-GE-129Additionally (because I already received recommendations/references for those, but with more I could cross check)
F100-PW-200
F100-PW-220
F100-PW-229…
Note: I am not asking the values shown in the Dash-1! In -1, there are only the limitations, but normal ops values are below those maximum acceptable values. What I need are the generally observed common/normal values.
You should have values for the GE 129 and PW-229 in one of your pm’s ages ago.