DCS Afterburner implementation?

[falcon_120]

Hello guys,

 

As far as I know in RL and in those aircraft with Afterburner, you either have military power or engage afterburner. The afterburner has a single stage either ON or OFF and no in-between, however in most aircraft in DCS we have some strange undetermined conitinous space where the afterburner has a long range of motion where is possible to be slighty engaged, so you see a small cone. Is that even possible in RL? I have always wandered myself why do we have such an implementation.

 

If not it would be nice if progressively ED change this behaviour in all aircrafts so the AB is a single state position that when engage is engage at max power (Just like the landing gear BTW). A good step forward is the F18 AB detetn button that avoids engaging it unconsciously.

[bolek]

A bunch of aircraft have more than one AB stage.

 

Viggen has 3 distinct AB stages (both in RL and in the sim), with cockpit indication.

 

Mig-21 and Su-33 have at least an extra "emergency" AB stage (used for carrier takeoff in Su-33).

 

Also, reportedly F-15C has five AB zones and this is modeled in the sim (but I can't find the reference).

[falcon_120]

A bunch of aircraft have more than one AB stage.

 

Viggen has 3 distinct AB stages (both in RL and in the sim), with cockpit indication.

 

Mig-21 and Su-33 have at least an extra "emergency" AB stage (used for carrier takeoff in Su-33).

 

Also, reportedly F-15C has five AB zones and this is modeled in the sim (but I can't find the reference).

But my point holds true, what we have now is an analog representation so u dont have 3, 4 or 5 levels of AB, you have like 30/40/100 depending on your throttle precision which is weird.

 

Enviado desde mi SM-G950F mediante Tapatalk

[Tippis]

That all depends on the module.

 

The Viggen does indeed only have three discrete AB stages; the Su-33 has its distinct extra stage; I haven't paid attention to the F-15 to say with any certainty, but it definitely feels like separate stages. The F-5 seems more like it's slow to respond than that it has some kind of analogue AB.

 

And petty much universally, they kick in at 75% throttle travel, coinciding with the detent on the Warthog and (presumably) other throttles that compete with it. The only weird thing is how poorly the zones are communicated in the different aircraft.

[feefifofum]

The F-15Cs stages of afterburner can be determined from the cockpit by the nozzle position gauge.

 

On what experience are you basing this assumption that all aircraft with afterburners exhibit solely on/off behavior? Do you have documentation to back up your assertions?

 

You don't, because ya don't know what you're talking about. ;)

 

Here are flight manuals for two airframes that directly contradict your assumptions.

 

TO 1F-15A-1, page 1-4A, change 5. 5 stages of afterburner in the F-15.

 

A1-F18AC-NFM-000, page 1-2-2. Sure sounds like an "analog" response to me.

 

EDIT: And what the heck, here's another one. Notice the reference to MIN and MAX afterburner, and that thrust modulation is provided "throughout the afterburner RANGE"

TO 1F-5E-1, page 1-15.

Edited August 28, 2018 by feefifofum

[Mars Exulte]

Yes, some aircraft have multistage afterburners, some do not, including in the game. Next!

[falcon_120]

The F-15Cs stages of afterburner can be determined from the cockpit by the nozzle position gauge.

 

On what experience are you basing this assumption that all aircraft with afterburners exhibit solely on/off behavior? Do you have documentation to back up your assertions?

 

You don't, because ya don't know what you're talking about. ;)

 

Here are flight manuals for two airframes that directly contradict your assumptions.

 

TO 1F-15A-1, page 1-4A, change 5. 5 stages of afterburner in the F-15.

 

A1-F18AC-NFM-000, page 1-2-2. Sure sounds like an "analog" response to me.

 

EDIT: And what the heck, here's another one. Notice the reference to MIN and MAX afterburner, and that thrust modulation is provided "throughout the afterburner RANGE"

TO 1F-5E-1, page 1-15.

 

 

I see that you have reading comprenhension problems. Please read again.

 

 

"On what experience are you basing this assumption that all aircraft with afterburners exhibit solely on/off behavior? Do you have documentation to back up your assertions? "

 

I suppose almost everyone understood me by i will try to explain it better for people like feefifofum. I do not say that every aircraft has an ON/OFF position, but either if it has only 1 position or multiple position, THESE ARE DISCRETE POSITIONS (5 in the case of the F15 and 3 in the viggen like some posters already said). Currently in the game, its seems like you dont have discrete posiotion but a kind of analog position. You can see this in the axis view window or from an F2 view, where you can slightly increase the throttle and obtain small increment in the AB response.

 

Anyhow this was a general comment, if ED is somehow addressing this in the future, good news and let move on.

[feefifofum]

Hello guys,

 

As far as I know in RL and in those aircraft with Afterburner, you either have military power or engage afterburner. The afterburner has a single stage either ON or OFF and no in-between

 

Your words. You go on to suggest that AB engage only when the throttle is pressed all the way forward. Not sure how I'm supposed to get "I understand there are multiple stages of afterburner" out of that. :lol:

 

The aircraft already respond in distinct stages when appropriate. Watch the nozzle position gauge in the F15. Watch the indicators in the Viggen cockpit. There's nothing to address.

[falcon_120]

Well when i expressed the general issue/doubt i had the F18 and F16 in mind. Hence i talked about ON/OFf.

 

I said nothing about the F15 it was a poster, and after his good remark i thought the point still holds true as you should have discrete positions.

 

Since i clearly presented a general doubt about how something is implemented in game and no about how it works in RL, your "you dont know what you are talking about" comment was way out of context.

 

Enviado desde mi SM-G950F mediante Tapatalk

 

EDIT: Just using the F15 as an example, if the plane has 5 stages of AB, shouldn't we see in the axis control window like 4 marks in the AB range, and no matter what you do with your throttle you should be able only to jump from one stage to the other, being impossible to stay between stages?

Edited August 28, 2018 by falcon_120

[Tippis]

Well when i expressed the general issue/doubt i had the F18 and F16 in mind. Hence i talked about ON/OFf.

 

This depends entirely on the engine make and model being used. GE engines generally do not have stages; P&W engines do. How they operate and respond to input past the AB detent again depends on the make and model — there are F-16:s with 5-stage, 11-stage, and no-stage engines, for instance. It's pretty much never just a case of on/off.

 

Just using the F15 as an example, if the plane has 5 stages of AB, shouldn't we see in the axis control window like 4 marks in the AB range, and no matter what you do with your throttle you should be able only to jump from one stage to the other, being impossible to stay between stages?

 

No. The control window just marks the input level of your controls — not the effect of that input. It has a dash at the AB detent because that's usually good to know, but just like how it doesn't have individual RPM checkmarks below that detent, it doesn't serve much purpose to have any AB zone detents above it. You use your instruments (if available) to monitor the state of your AB; you use the control window to monitor where your throttle input is. Since the throttle input is a continuous axis, so is the control display.

 

It is already the case that you only can jump from one stage to the other (if the engine is built that way).

[falcon_120]

No. The control window just marks the input level of your controls — not the effect of that input. It has a dash at the AB detent because that's usually good to know, but just like how it doesn't have individual RPM checkmarks below that detent, it doesn't serve much purpose to have any AB zone detents above it. You use your instruments (if available) to monitor the state of your AB; you use the control window to monitor where your throttle input is. Since the throttle input is a continuous axis, so is the control display.

 

It is already the case that you only can jump from one stage to the other (if the engine is built that way).

 

I see, so currently in the case of the F15 (for the sake of my example but extensible to the rest) you can only actually move between one of the 5 stages. I haven't been able to see that behaviour when looking at the cockpit throttle position or any other instrument indicator, but i will pay close attention this afternoon. I really was under the impression that this not working as you describes but that you also see the game pilot hand moving in an analogue way, provided this isn't the case my initial concern makes no sense now :).

[QuiGon]

It totally depends on the aircraft. Two examples:

 

While the Viggen has indeed 3 AB stages, they are still analog. You can smoothly move the throttle across the 3 stages. There are two AB indicators in the cockpit. A "digital" one which only shows the AB stage you are in and then an analog indicator that shows the exact throttle position within the 3 stages (see attached screenshots). The throttle can be moved within each stage (stage 3 beeing bigger than the first two stages btw), which changes the amount of fuel that is directly injected into the engine exhaust.

 

The MiG-21 on the other hand really has 2 distinct AB stages that can only be enabled or disabled (not by throttle movements, but by two switches, one for each stage), which is what you are talking about. That means the amount of fuel that gets directly injected into the engine exhaust is fixed to the two stages and can not be gradually changed by the pilot, unlike in the Viggen.

Edited August 28, 2018 by QuiGon
More detailed explanation

[falcon_120]

Interesting, thanks!

I do not own neither the viggen nor the mig21, but that is good to know.

 

Enviado desde mi SM-G950F mediante Tapatalk

[QuiGon]

I just edited and extended my previous post to give a better explanation of how this works.

[feefifofum]

Since i clearly presented a general doubt about how something is implemented in game and no about how it works in RL, your "you dont know what you are talking about" comment was way out of context.

 

 

As far as I know in RL...

 

:music_whistling: You're a funny guy.

 

The F-16 also has more than one afterburner setting. See TO GR1F-16CJ-1, page 1-29

[falcon_120]

@Feefifofum I already clarified all that and what i meant. If you still don't get it i'm sorry for your limitations ...XD

[mvsgas]

Falcon_120,

I think that the confusion might come from the expectation that the different AB stages are notches on the Throttle. Is that what you thought it should be on your original post? Did you think the throttle in real life have different bumps or notches to indicate the stages? I am not trying to make fun simple trying to understand your original post.

 

Now, about F-15 AB stages.

AFAIK, this is related to the F100-PW-100/220/229. (My overly simplified version, but long winded description)

The stages mention on the RL Manuals for the F-15, commonly known and Technical Orders (T.O.) are talking about the AB fuel spray ring on the exhaust. This spray fuel at different power level angle (PLA) or throttle position. As you advance the throttle forward another of the rings will open and send more fuel to the exhaust. This in term create a bigger flame, and so on. There is no specific engine positions indication for the pilot to tell what stage of AB he is on. The only indicators he might have is at minimum AB nozzle should be around this percentage and at max ab is should be this. Fuel flow will not be reliable enough and he will only look for it to increase.

If you look for videos of F-15 or F-16 with PW engine you can see the ring is each stage opens.

https://forums.eagle.ru/showpost.php?p=3457787&postcount=66

 

Now F-16 with other engines like the F110-GE-100, also have various levels of AB, but there not call stages like on PW engine. GE uses spray bars as oppose to PW spray rings.

 

AFAIK, control AB (meaning different level of after burner at different throttle positions) goes back as far as the J57 engine.

[falcon_120]

Hi Mvsgas,

 

More or less yes. Actually my post was triggered by a bunch of youtube videos (I will look for them to show perfectly what i meant). My impression from those videos was that the afterburner was something like a force detent or similar that requires some force, but once you make the needed force inmediately "clicks" to his max position. I thought something similar to the shift in a car. In the videos i-m reffering to it seems like you need to make a good effort to activate the AB and once you do it is not like you can holdit until it reaches "his position" (where is suppose to fit) Sorry about my bad wording but my main language is not english.

[Exorcet]

The AB stages are distinct in the sim, not continuous. In the F-15 for example, you can't smoothly control your speed in AB like you can in dry thrust. The thrust will jump in steps in AB.

[mvsgas]

Hablame en español si queres.

No lo escribo bien pero tratare. La forma que el AB se inicia es diferente en cada avión. Mi experiencia es limitada al F-16, en ese avión, para empezar el AB, uno levanta la palanca del acelerador i la mueves para el frente. Pero ya que esta ahí, no ay una indicasion física excepto la posición del la boquilla de escape y el uso de el combustible aumenta.

[falcon_120]

Hablame en español si queres.

No lo escribo bien pero tratare. La forma que el AB se inicia es diferente en cada avión. Mi experiencia es limitada al F-16, en ese avión, para empezar el AB, uno levanta la palanca del acelerador i la mueves para el frente. Pero ya que esta ahí, no ay una indicasion física excepto la posición del la boquilla de escape y el uso de el combustible aumenta.

Gracias mvsgas :). But dont worry i understand it well now xd. I guess also that this varies a lot depending on the specific fighter. I will try to find the videos i'm talking about because some of them were of the Mirage2000, eurofighter, f18 and rafale. But given all the information of this thread it is clear that it was probably a wrong perception from my side. Thanks!

 

Enviado desde mi SM-G950F mediante Tapatalk

[Frederf]

F-16, F-15, F-18, MiG-21, F-4, F-5 all have continuously variable thrust in the augmented range. For every two thrust values in the range minimum to maximum augmentation there is a thrust value available between them.

 

It is kind of like gears on a car. If you go from 2nd gear to 3rd gear it doesn't mean the force jumps. There is also the metering of air by the throttle. The difference with a jet engine is the throttle is fuel flow instead of air flow in a car.

 

To find afterburners without continuous thrust adjustment you have to go back in history a ways like J46 engine of 1950s which was going to have electronic fuel control by design but it was converted to binary operation before introduction.