What is the best way to set the after burner
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Popular misconception that there is any RPM change once the AB is lit…I used to work for GE in After Burner Controls and it took me a bit to get over this myself.
Once the engine gets to mil power it is effectively “at” 100% design RPM, but that physical RPM will vary with altitude. So what you want to do is set your MIN AB stop just at the mil power setting…then set MAX AB at max controller travel. Whatever travel you get between MIL and MAX will be the closest you can get to RL throttle rigging for your controller and its calibration, but your core engine RPM should not change between MIL power and MAX AB.
The flat spot in your curve can be thought of as the light-off time (delay) for the burner post-selection - and that varies with altitude and speed as well…it’s worst when you are high and slow.
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Thanks both of you for the answer and thanks @Stevie for the indepth explanation!
Now I’m still not sure what the visual cue are to know exactly where is MIL power setting ingame. Is it exactly to the point where noz poz needle starts to move? Or is it a set RPM like 109%? Or the red line on RPM gauge? With your knowledge of engine, how do YOU set the afterburner in BMS?
Thanks a lot!
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@Mikyjax There is an option to enable an audible click when passing from MIL to min AB as a que.
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@BVT_9 Thanks! I found this line set g_nAfterburnerDetentClick 314 but I can’t hear it, not sure if it’s still in 4.37.
Anyway it seems correctly setup now, I set it when the RPM is maxed out and noz poz not moving, when I pass the cougar detent the noz pos increases so I guess it’s correct
Thanks guys.
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@Mikyjax said in What is the best way to set the after burner:
g_nAfterburnerDetentClick
It’s a boolean … just 0 or 1. Can’t customize the soundId, yet. It’s on the todo list… the default sound is very quiet.
set g_bAfterburnerDetentClick 1
If in doubt you can also hit [shift+3] which will show you throttle position (green = MIL range; red = AB range).
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@Mikyjax I think it is still there, but it’s a very quiet click sound.
Besides I still wondering about the graph above. From my side, the implementation of that would be useful. I have a physical detent on my controller, and I could put it to the middle of the flat part. So if I push the throttle forward to my physical detent, than I could be sure I’m already at full Mil power but not in a minimal AB.
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Also for those who have physical detents/bumps on their throttle axis … in addition to setting the detent in Alt Launcher or in-game Setup screen … you can set it in-flight with the SetLeftThrottleAbDetent callback.
Can be useful if you find it’s a little off, mid flight… invoking it has the effect of putting your throttle immediately to 100% full MIL.
SetLeftThrottleAbDetent 314 0 0XFFFFFFFF 0 0 0 1 "TQS: SET AB DETENT - Left Engine"
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@hiuuz Yep, I think I will use a small flat there too.
@airtex2019 Brilliant… again, Devs thought of everything ^^
Thanks a lot guys! -
@Mikyjax Fuel flow rate change, is for me the basic visual cue that AB has kicked in.
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@Mikyjax I upped the volume of the click to max in the soundproto file, to me it is VERY clear
See this thread on how I reduced the ECS sound volume: https://forum.falcon-bms.com/topic/22823/reduce-internal-engine-sound
Obviously this also works to increase individual sounds like the AB-click -
@Mikyjax - that’s sort of a tough call, because BMS Setup sort of allows you to set it wherever you’d like…if you have one of the new Thrustmaster Viper Throttles you can simply use the rail stops…and that’s the most straight forward. (I initially wasn’t going to put a throttle rail in my cockpit build until I realized this…)
But other than that it’s sort of a matter of how much control throw you’d like from MIN to MAX AB. And that can vary too - the GE engine has a continually throttled AB (that’s what I used to work on), and the Pratt engine “kicks in” by successively lighting seven (as I recall) burner rings/Segments…so you may find you want to do something different for each, depending on the Block jet you are dealing with.
I think once you set that BMS will adjust the calibration from Idle to MIL for itself.
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@Mikyjax said in What is the best way to set the after burner:
Hello guys,
I wonder what the most “scientific” way is to set the after burner.
What is the cue you are looking for? Noz pos moving? specific rpm on the ground under set temperature? Look for cues in external view?When I simply bring my throttle before the detent on the cougar and set the AB, I often found that it’s not at full mil since everybody is flying faster than I am (even if they let me a few rpm margin) so I bring the throttle back a bit and set the AB again but I find this quite approximative and would like a very good way to be sure it’s perfectly setup.
Thanks,
MikeHi Miky!!! How are you doing buddy?!
On F-16, AB instrument cue is the NozPos.
(when LG is up)
Nozzle closed (<5) => Idle to Mil
As soon as is opens again (>10) => ABOf course, significant FF increases is also a good cue.
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@Dee-Jay said in What is the best way to set the after burner:
On F-16, AB instrument cue is the NozPos.
(when LG is up)
Nozzle closed (<5) => Idle to Mil
As soon as is opens again (>10) => ABOf course, significant FF increases is also a good cue.
This can be tricky too, because if BMS models the Nozzle behavior correctly, you should see the Nozzle pre-open just prior to light-off to induce flow. Then once the burner is lit the Nozzle will close a bit to establish Mach 1 at the Nozzle throat - so watch for this.
Fuel Flow is really your better/most stable indicator.
There is also a difference between the GE and Pratt engines here, in that the GE ones include feedback to “know” that the AB is actually lit - a “fire eye”. The Pratt engines don’t have that.
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@Dee-Jay Doing great my friend, hope that you too
Thanks for your input!I think I will stick with @airtex2019 solution :
SetLeftThrottleAbDetent 314 0 0XFFFFFFFF 0 0 0 1 “TQS: SET AB DETENT - Left Engine”
Setting mil power ingame with a button and that’s it, all I care about is to be as close as Mil power as bms can be and this seems the most straight forward approach.Thanks again to all of you for your advanced explanations
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@Stevie said in What is the best way to set the after burner:
Fuel Flow is really your better/most stable indicator.
There is also a difference between the GE and Pratt engines here, in that the GE ones include feedback to “know” that the AB is actually lit - a “fire eye”. The Pratt engines don’t have that.
I use FF as the reference, but is the “fire eye” modelled in BMS? I can’t say I’ve seen it.
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@Tiger-0 - You wouldn’t notice - and that’s the point. It’s the fire eye that allows the GE engine to know when it has had a flameout, and to auto-relight as long as the pilot hasn’t put the throttle to cutoff. No other pilot action required.
The Pratt isn’t that smart, and both spotting a flameout and performing a relight/restart differ. Pilot attention/action required.
So the only way you’d “notice” would be a difference in flameout procedure between GE and Pratt powered Vipers.