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Zone 6: Air Source Off - Modeled?


Callsign JoNay

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It’s important to note that defeating the mid-compression bypass doesn’t give you thrust, it just prevents it from being taken away under certain conditions. If you don’t fly in those conditions (mainly pushing past 15 units AoA) you wouldn’t notice the difference.

And I don’t think the bleeds take that much power from the engines, certainly not compared to the boundary layer control on the MiG-21, and while you can fly with the air source off or in ram it does shut off the radar that you may need to kill things. Might also inhibit gun firing?

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9 hours ago, r4y30n said:

And I don’t think the bleeds take that much power from the engines, certainly not compared to the boundary layer control on the MiG-21, and while you can fly with the air source off or in ram it does shut off the radar that you may need to kill things. Might also inhibit gun firing?

 

You wouldn't think so. Then again, my car can barely get itself over a steep hill if I have the AC on. The real world F-14 pilots used these tricks for a reason. And it would be fun to have a reason to use the air source controls in DCS for some reason other than setting and forgetting during the ramp start.

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vor einer Stunde schrieb Callsign JoNay:

 And it would be fun to have a reason to use the air source controls in DCS for some reason other than setting and forgetting during the ramp start.

FWIW, you'd still need them set to on to operate the gun. And you should set air source to "left engine" during AAR: granted, zero impact in the sim, but if you want to roleplay... 😉🙂

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10 hours ago, r4y30n said:

It’s important to note that defeating the mid-compression bypass doesn’t give you thrust, it just prevents it from being taken away under certain conditions. If you don’t fly in those conditions (mainly pushing past 15 units AoA) you wouldn’t notice the difference.

And I don’t think the bleeds take that much power from the engines, certainly not compared to the boundary layer control on the MiG-21, and while you can fly with the air source off or in ram it does shut off the radar that you may need to kill things. Might also inhibit gun firing?

 

All of this is correct. If you spend more than 10 seconds thinking about it, there is no reason anyone would fly into a combat situation with the air source off to a get a miniscule boost in thrust. Why would you fly into combat with the WCS off (not just in standby, OFF!) and unable to fire the gun? On top of that, the cockpit would become very warm, very quickly. Something you don't have to deal with in DCS, but a factor in the real world. I can practically assure you that no pilots did this in real life and it's most likely an embellishment that makes for a good story. This is the same as the full flap deployment while combat maneuvering myth.


Edited by fat creason
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Systems Engineer & FM Modeler

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I mean, my car gets hot when I'm driving up the hill with my AC off too, but I turn it back on when I get to the top of the hill. It doesn't take 10 seconds of thinking to do it. 

 

We have stories of real pilots doing it, not sure what the problem is. Embellished maybe, but fabricated? I doubt it. And it just makes sense from a physics standpoint. Cooling the cabin and avionics and enabling the gun is work. Work requires an energy conversion. Energy can't be converted without friction, etc. The air source set to something other than off should slow down the aircraft to some extent and I'm just asking if it's modeled. I guess the answer is no. 🙃

 


Edited by Callsign JoNay
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2 minutes ago, Callsign JoNay said:

We have stories of real pilots doing it, not sure what the problem is.

 

I would argue the potential issue is we're in a fighter, our job is to kill things, and we just disabled 3/4s of our weaponry for a marginal increase in engine performance. That might have happened in training where pipper on counts as a kill and you can just cage the gunsight at 53 mils. In a sim where stuff is actually shooting back... it seems a bit silly. 

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The goal is to simulate reality right? In reality the air source would slow down the jet. Am I wrong? 

 

I don't understand why there is a resistance to model this? What if I'm just in a free flight, have no need for a gun or a WCS, and I just want to see how fast I can go? You think it's silly to turn off air in combat? Ok, fine, that's your choice to leave it on. 

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3 minutes ago, Callsign JoNay said:

The goal is to simulate reality right? In reality the air source would slow down the jet. Am I wrong? 

 

I don't understand why there is a resistance to model this? What if I'm just in a free flight, have no need for a gun or a WCS, and I just want to see how fast I can go? You think it's silly to turn off air in combat? Ok, fine, that's your choice to leave it on. 

 

Thing is, it is modelled but the effect is so minor you won't notice it. And yes, it is silly to turn it off in combat as you disable the systems that you need to defeat the enemy.

That said all our SMEs have basically unanimously said that it is ridiculous and not something anyone ever did for real.

 

And like @fat creason mentioned, it's just as with the flaps, one or two high profile pilots saying it's a thing but all the other guys say it's ridiculous.

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14 minutes ago, Callsign JoNay said:

Oh it is modeled? Why didn't you say so? How can I measure its effect?

 

 

 

12 hours ago, r4y30n said:

It’s important to note that defeating the mid-compression bypass doesn’t give you thrust, it just prevents it from being taken away under certain conditions. If you don’t fly in those conditions (mainly pushing past 15 units AoA) you wouldn’t notice the difference.

And it's not about turning off the air source, it's the mid-compression bypass. There's a keybind for it.


Edited by Naquaii
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1 minute ago, Callsign JoNay said:

Just to be clear, I'm asking about air source not mid compression bypass CB. 

 

To confirm, it is modeled? If so, what is the best way to measure it?

 

If you're speaking about getting improved engine performance by setting the Air Source to OFF, then no, that's not modelled. There's just no evidence for that doing anything at all. The mid-compression bypass has some evidence for it making a difference but so little it in reality isn't even noticable.

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Yup..one or two pilots you claim..yet there are books talk of the "prohibited" actions being used but not by the majority..

The F14 association forum board (before the server crash, that board had a lot of experienced stories in WVR arena.. e.g. going up against a F16 in a slow speed spiral climb, against F15, F18..etc) talked about it a great deal when Hoser (through someone and even his book) and others talked about it. Hoser's thread was huge! Talked about depart flight and knowing where your plane will in space..a la shortcut.. Cartwheeling, asymmetrical thrust..etc..

Also, Maintainers talked about repairing the torque tube.






Sent from my SM-G998U using Tapatalk

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4 minutes ago, jcdata said:

Yup..one or two pilots you claim..yet there are books talk of the "prohibited" actions being used but not by the majority..

The F14 association forum board (before the server crash, that board had a lot of experienced stories in WVR arena.. e.g. going up against a F16 in a slow speed spiral climb, against F15, F18..etc) talked about it a great deal when Hoser (through someone and even his book) and others talked about it. Hoser's thread was huge! Talked about depart flight and knowing where your plane will in space..a la shortcut.. Cartwheeling, asymmetrical thrust..etc..

Also, Maintainers talked about repairing the torque tube.

 

 

 

 


Sent from my SM-G998U using Tapatalk
 

 

 

 

 

You have to try and see our side here though, we have tons of documentation not mentioning this, not to mention all our SMEs agreeing that this wasn't used, didn't make a difference and wasn't a good idea. Then changing this arbitrarily from hearsay just isn't a thing. Remember, even if we would change it from just word of mouth we still have no hard numbers on what it would actually do.

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The engine bleed on the F14 or any fighter sized aircraft is minuscule. It provide a low pressure differential, 5.5 psi, to a very small cockpit volume and cooling for avionics. It isn't like an airliner bleed system that must pressurize a huge cabin area at 8.6 or higher psi differential. 

 

Turning off air source was a dumb idea, the VDI and HUD would overheat and fail in addition to the weapons systems issues that have already been described. The folks who said they did it were more about pretending to look clever than any real advantage. 

 

How long are you going to stay "stuck on stupid"? I mean really, get a life people.

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Viewpoints are my own.

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18 minutes ago, Naquaii said:

 

Remember, even if we would change it from just word of mouth we still have no hard numbers on what it would actually do.

 

Fair enough. Really, that's all you need to say.

 

It's a more constructive reply than saying "we haven't modeled it because we believe the stories are an embellishment and we don't think it would be a smart thing to do in combat", which quite frankly is missing the point.

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6 minutes ago, Callsign JoNay said:

 

Fair enough. Really, that's all you need to say.

 

It's a more constructive reply than saying "we haven't modeled it because we believe the stories are an embellishment and we don't think it would be a smart thing to do in combat", which quite frankly is missing the point.

 

Regardless it's also a fact that there's simply not any substantial evidence of it at all, hard numbers non-withstanding.

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1 hour ago, Victory205 said:

Turning off air source was a dumb idea, the VDI and HUD would overheat and fail in addition to the weapons systems issues that have already been described.

 

Nobody is suggesting turning off the air source at fence in and leaving it off for an extended period of time. Think more along the lines of disabling it while in the up hill to get every pound of thrust possible before coming over the top of an aggressor F-16 and then turning it back on before trigger down in the down hill. Is that going to bust the WCS and turn the cabin into a convection oven? If so, then that sounds like more than a miniscule energy pull.


Edited by Callsign JoNay
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1 hour ago, Callsign JoNay said:

 

Nobody is suggesting turning off the air source at fence in and leaving it off for an extended period of time. Think more along the lines of disabling it while in the up hill to get every pound of thrust possible before coming over the top of an aggressor F-16 and then turning it back on before trigger down in the down hill. Is that going to bust the WCS and turn the cabin into a convection oven? If so, then that sounds like more than a miniscule energy pull.

 

I would love to watch a RIO in the back trying to screw with CBs during ACM.

DCS F/A-18C :sorcerer:

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1 hour ago, Wizard_03 said:

I would love to watch a RIO in the back trying to screw with CBs during ACM.

Air source is changed in pilot's pit and they are buttons.


Edited by draconus
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