Winter Wear Enforcement
11-29-2019, 06:27 AM
#62
Line Holder
Joined APC: Mar 2018
Posts: 55
Match left pack output temp to the actual temp. If actual temp goes below 15, you’re options are to close the cockpit door or shut off the pack.[/QUOTE]
If you’re going to sit in the cockpit and not leave it. Put the ECS page up, leave it up and put the left pack in manual then set your temp. That works really well.
If you’re going to sit in the cockpit and not leave it. Put the ECS page up, leave it up and put the left pack in manual then set your temp. That works really well.
11-29-2019, 08:51 AM
#63
Gets Weekends Off
Joined APC: Jan 2017
Posts: 527
Originally Posted by pangolin
I think it’s the pack temp to to the selected. You have 2 temps. Actual. Selected. Pack.
The knobs (reflected in the “selected” temp) control what you want the final state of the “actual” to be. In other words, it’s just a thermostat that aims to control what’s measured in the room/cabin (or, “actual”). And it does this by varying the pack temp. Some misguided common sense might tell you that if you’re most comfortable at 25 degrees and therefore you want the “actual” to be 25 degrees so you put the “selected” to 25 degrees, the controller should make the pack temp 25 degrees to accomplish that. Two problems with that. First, it would take forever to replace the entire cabin volume of air with the new, 25 degree air. Second, there are influences of the cabin air temp besides what the packs put out. Human bodies, sunlight, and hot air through the skin adding heat, or cold air through the skin or the open door cooling it down. So, due to the slowness of the air replacement and the external influences, just setting the pack temp to 25 would not accomplish anything.
Because of this, the logic of the controller looks at the difference between the “actual” and the “selected”, (say, actual is 24 and selected is 25; you’re telling it you want to raise the cabin temp by 1 degree) it will initially make the pack temp 10 degrees hotter than actual so as to get some change happening. If you want to raise the cabin temp 5 degrees (actual=20, selected=25) it will start off with a much higher pack temp, maybe 30 higher than actual. I’m just throwing out example numbers here, but thank of it as a multiplier. (It takes the difference between actual and selected, and makes the difference between actual and pack that much higher.) Over the next few minutes, as the change starts taking effect, and the difference between actual and selected shrinks, the controller will gradually move the pack temp closer to actual so as to shrink that difference too, and prevent an overshoot. Ultimately (with the varying disturbances, this might or might not even happen by the time the flight is over) actual will reach, and stabilize at, selected, since it’s continuously looking at the difference between those 2 temps and doing whatever it takes to drive it to zero... in other words again, the basic job of a thermostat. (A very long flight at night will give the system the biggest chance to reach equilibrium. The actual will be stable at the selected value, but the pack temp will be higher to compensate for the constant heat loss through the skin at cruise altitude.)
This is why when we’re waking the jet up on a winter morning, even though the lowest possible “selected” temp (15) is selected, the pack temp will always start out maxed out at 80 or so... because the actual is still way below the selected, which tells the controller to raise the temp in a major way. Also, since the left pack controller measures the “actual” in the cockpit which is very susceptible to disturbances (namely, cold air through the door) in response to which it will command huge temps for the last 4 rows, is why the company recommends to turn that pack off and run the whole plane off the right pack, which measures a much more stable “actual” from the average of a sensor in the middle and a sensor in the back of the cabin.
Also, if you turn the left pack on right after closing the door, the same problem (cold air in the cockpit) still exists, as it takes some time to replace this air; and in the interim, the controller will still respond by baking the last 4 rows. But if you patiently wait a couple of minutes (like theUpsideDown said, wait till the second engine start) then the cockpit air will be replaced with the nice, stable and slightly warm air from the right pack that’s measured in response to the cabin, and when you start the left pack the controller won’t be measuring in response to unrealistic cold air. Here’s the key, when you turn the left pack on, set the “selected” to be the same as “actual!” This will ensure that the initial commanded pack temp will be the closest possible to what’s already in the cockpit with no difference to shrink with big pack swings. (Also, ignore that it initially goes down to -20 degrees, it’s just a normal part of the startup process. It’ll go down, then it’ll go back up, and then initially stabilize somewhere. Only after it stabilizes, then you can start your normal fine-tuning tweaks.)
As far as the normal fine-tuning tweaks that you do for the rest of the flight, keep in mind that even though what’s displayed to us is whole degrees, the system actually measures and operates on finer measurements. Also keep in mind the “multiplier” that I mentioned earlier, it’s pretty big. Which is why a tiny needle-width tweak of the knob might not even show a change in the “selected” (the decimal control didn’t reach to where it rounds to the next whole degree) but it will still cause at least a few degrees’ response in the pack temp. And that response will be slow! So, once the flight is going, always have the patience to let the pack temp finish moving before making further tweaks. If you make a change while it’s still moving, you’re making a change without knowing what you’re responding to, so you’re shooting in the blind and setting yourself up for big oscillations. It’s like turning the shower knob, not getting the immediate result, quickly turning it more, and getting burned when the first and second change finally take effect together.
By the way, what I’ve been calling the “pack” temperature (the one in the box) just to keep consistent with what others have been calling it, isn’t measured at the pack, it’s in the supply duct far downstream of that (downstream of the mixing manifold, actually). I would almost go back in my post and change “pack” to “duct” (which is what I normally call it) but... nah.
11-29-2019, 09:15 AM
#64
Gets Weekends Off
Joined APC: Mar 2019
Posts: 315
Originally Posted by vessbot
There is no direct control for the pack output temp (the one in the box) and this misunderstanding is the source of many people’s frustrations with the system. (“Why’d the temp just run away, I didn’t touch a thing!” Or, “... I only tweaked it a degree!”)
The knobs (reflected in the “selected” temp) control what you want the final state of the “actual” to be. In other words, it’s just a thermostat that aims to control what’s measured in the room/cabin (or, “actual”). And it does this by varying the pack temp. Some misguided common sense might tell you that if you’re most comfortable at 25 degrees and therefore you want the “actual” to be 25 degrees so you put the “selected” to 25 degrees, the controller should make the pack temp 25 degrees to accomplish that. Two problems with that. First, it would take forever to replace the entire cabin volume of air with the new, 25 degree air. Second, there are influences of the cabin air temp besides what the packs put out. Human bodies, sunlight, and hot air through the skin adding heat, or cold air through the skin or the open door cooling it down. So, due to the slowness of the air replacement and the external influences, just setting the pack temp to 25 would not accomplish anything.
Because of this, the logic of the controller looks at the difference between the “actual” and the “selected”, (say, actual is 24 and selected is 25; you’re telling it you want to raise the cabin temp by 1 degree) it will initially make the pack temp 10 degrees hotter than actual so as to get some change happening. If you want to raise the cabin temp 5 degrees (actual=20, selected=25) it will start off with a much higher pack temp, maybe 30 higher than actual. I’m just throwing out example numbers here, but thank of it as a multiplier. (It takes the difference between actual and selected, and makes the difference between actual and pack that much higher.) Over the next few minutes, as the change starts taking effect, and the difference between actual and selected shrinks, the controller will gradually move the pack temp closer to actual so as to shrink that difference too, and prevent an overshoot. Ultimately (with the varying disturbances, this might or might not even happen by the time the flight is over) actual will reach, and stabilize at, selected, since it’s continuously looking at the difference between those 2 temps and doing whatever it takes to drive it to zero... in other words again, the basic job of a thermostat. (A very long flight at night will give the system the biggest chance to reach equilibrium. The actual will be stable at the selected value, but the pack temp will be higher to compensate for the constant heat loss through the skin at cruise altitude.)
This is why when we’re waking the jet up on a winter morning, even though the lowest possible “selected” temp (15) is selected, the pack temp will always start out maxed out at 80 or so... because the actual is still way below the selected, which tells the controller to raise the temp in a major way. Also, since the left pack controller measures the “actual” in the cockpit which is very susceptible to disturbances (namely, cold air through the door) in response to which it will command huge temps for the last 4 rows, is why the company recommends to turn that pack off and run the whole plane off the right pack, which measures a much more stable “actual” from the average of a sensor in the middle and a sensor in the back of the cabin.
Also, if you turn the left pack on right after closing the door, the same problem (cold air in the cockpit) still exists, as it takes some time to replace this air; and in the interim, the controller will still respond by baking the last 4 rows. But if you patiently wait a couple of minutes (like theUpsideDown said, wait till the second engine start) then the cockpit air will be replaced with the nice, stable and slightly warm air from the right pack that’s measured in response to the cabin, and when you start the left pack the controller won’t be measuring in response to unrealistic cold air. Here’s the key, when you turn the left pack on, set the “selected” to be the same as “actual!” This will ensure that the initial commanded pack temp will be the closest possible to what’s already in the cockpit with no difference to shrink with big pack swings. (Also, ignore that it initially goes down to -20 degrees, it’s just a normal part of the startup process. It’ll go down, then it’ll go back up, and then initially stabilize somewhere. Only after it stabilizes, then you can start your normal fine-tuning tweaks.)
As far as the normal fine-tuning tweaks that you do for the rest of the flight, keep in mind that even though what’s displayed to us is whole degrees, the system actually measures and operates on finer measurements. Also keep in mind the “multiplier” that I mentioned earlier, it’s pretty big. Which is why a tiny needle-width tweak of the knob might not even show a change in the “selected” (the decimal control didn’t reach to where it rounds to the next whole degree) but it will still cause at least a few degrees’ response in the pack temp. And that response will be slow! So, once the flight is going, always have the patience to let the pack temp finish moving before making further tweaks. If you make a change while it’s still moving, you’re making a change without knowing what you’re responding to, so you’re shooting in the blind and setting yourself up for big oscillations. It’s like turning the shower knob, not getting the immediate result, quickly turning it more, and getting burned when the first and second change finally take effect together.
By the way, what I’ve been calling the “pack” temperature (the one in the box) just to keep consistent with what others have been calling it, isn’t measured at the pack, it’s in the supply duct far downstream of that (downstream of the mixing manifold, actually). I would almost go back in my post and change “pack” to “duct” (which is what I normally call it) but... nah.
The knobs (reflected in the “selected” temp) control what you want the final state of the “actual” to be. In other words, it’s just a thermostat that aims to control what’s measured in the room/cabin (or, “actual”). And it does this by varying the pack temp. Some misguided common sense might tell you that if you’re most comfortable at 25 degrees and therefore you want the “actual” to be 25 degrees so you put the “selected” to 25 degrees, the controller should make the pack temp 25 degrees to accomplish that. Two problems with that. First, it would take forever to replace the entire cabin volume of air with the new, 25 degree air. Second, there are influences of the cabin air temp besides what the packs put out. Human bodies, sunlight, and hot air through the skin adding heat, or cold air through the skin or the open door cooling it down. So, due to the slowness of the air replacement and the external influences, just setting the pack temp to 25 would not accomplish anything.
Because of this, the logic of the controller looks at the difference between the “actual” and the “selected”, (say, actual is 24 and selected is 25; you’re telling it you want to raise the cabin temp by 1 degree) it will initially make the pack temp 10 degrees hotter than actual so as to get some change happening. If you want to raise the cabin temp 5 degrees (actual=20, selected=25) it will start off with a much higher pack temp, maybe 30 higher than actual. I’m just throwing out example numbers here, but thank of it as a multiplier. (It takes the difference between actual and selected, and makes the difference between actual and pack that much higher.) Over the next few minutes, as the change starts taking effect, and the difference between actual and selected shrinks, the controller will gradually move the pack temp closer to actual so as to shrink that difference too, and prevent an overshoot. Ultimately (with the varying disturbances, this might or might not even happen by the time the flight is over) actual will reach, and stabilize at, selected, since it’s continuously looking at the difference between those 2 temps and doing whatever it takes to drive it to zero... in other words again, the basic job of a thermostat. (A very long flight at night will give the system the biggest chance to reach equilibrium. The actual will be stable at the selected value, but the pack temp will be higher to compensate for the constant heat loss through the skin at cruise altitude.)
This is why when we’re waking the jet up on a winter morning, even though the lowest possible “selected” temp (15) is selected, the pack temp will always start out maxed out at 80 or so... because the actual is still way below the selected, which tells the controller to raise the temp in a major way. Also, since the left pack controller measures the “actual” in the cockpit which is very susceptible to disturbances (namely, cold air through the door) in response to which it will command huge temps for the last 4 rows, is why the company recommends to turn that pack off and run the whole plane off the right pack, which measures a much more stable “actual” from the average of a sensor in the middle and a sensor in the back of the cabin.
Also, if you turn the left pack on right after closing the door, the same problem (cold air in the cockpit) still exists, as it takes some time to replace this air; and in the interim, the controller will still respond by baking the last 4 rows. But if you patiently wait a couple of minutes (like theUpsideDown said, wait till the second engine start) then the cockpit air will be replaced with the nice, stable and slightly warm air from the right pack that’s measured in response to the cabin, and when you start the left pack the controller won’t be measuring in response to unrealistic cold air. Here’s the key, when you turn the left pack on, set the “selected” to be the same as “actual!” This will ensure that the initial commanded pack temp will be the closest possible to what’s already in the cockpit with no difference to shrink with big pack swings. (Also, ignore that it initially goes down to -20 degrees, it’s just a normal part of the startup process. It’ll go down, then it’ll go back up, and then initially stabilize somewhere. Only after it stabilizes, then you can start your normal fine-tuning tweaks.)
As far as the normal fine-tuning tweaks that you do for the rest of the flight, keep in mind that even though what’s displayed to us is whole degrees, the system actually measures and operates on finer measurements. Also keep in mind the “multiplier” that I mentioned earlier, it’s pretty big. Which is why a tiny needle-width tweak of the knob might not even show a change in the “selected” (the decimal control didn’t reach to where it rounds to the next whole degree) but it will still cause at least a few degrees’ response in the pack temp. And that response will be slow! So, once the flight is going, always have the patience to let the pack temp finish moving before making further tweaks. If you make a change while it’s still moving, you’re making a change without knowing what you’re responding to, so you’re shooting in the blind and setting yourself up for big oscillations. It’s like turning the shower knob, not getting the immediate result, quickly turning it more, and getting burned when the first and second change finally take effect together.
By the way, what I’ve been calling the “pack” temperature (the one in the box) just to keep consistent with what others have been calling it, isn’t measured at the pack, it’s in the supply duct far downstream of that (downstream of the mixing manifold, actually). I would almost go back in my post and change “pack” to “duct” (which is what I normally call it) but... nah.
I find it amusing that you took the time to write this though. Good job explaining! Lol.
11-29-2019, 04:30 PM
#65
Line Holder
Joined APC: Sep 2018
Posts: 38
The FOM states "Approved "outer wear" apparel includes only the black raincoat/ weather coat, jacket with braids," and so on...
Why wouldn't a London Fog or any other black overcoat be acceptable as "uniform identical style and color" ?
I'm a pretty slender guy and the leather jacket makes me look like a marshmallow, I have been considering a new black trench/over coat. Probably best to reach out to the CPO for clarification.
Why wouldn't a London Fog or any other black overcoat be acceptable as "uniform identical style and color" ?
I'm a pretty slender guy and the leather jacket makes me look like a marshmallow, I have been considering a new black trench/over coat. Probably best to reach out to the CPO for clarification.
12-01-2019, 05:10 AM
#66
Line Holder
Thread Starter
Joined APC: Apr 2019
Posts: 38
Originally Posted by AvrgPilot
The FOM states "Approved "outer wear" apparel includes only the black raincoat/ weather coat, jacket with braids," and so on...
Why wouldn't a London Fog or any other black overcoat be acceptable as "uniform identical style and color" ?
I'm a pretty slender guy and the leather jacket makes me look like a marshmallow, I have been considering a new black trench/over coat. Probably best to reach out to the CPO for clarification.
Why wouldn't a London Fog or any other black overcoat be acceptable as "uniform identical style and color" ?
I'm a pretty slender guy and the leather jacket makes me look like a marshmallow, I have been considering a new black trench/over coat. Probably best to reach out to the CPO for clarification.
The M & H website looks like it was designed in 1997 and doesn’t have much on it. Can anyone post a picture of the M & H trench coat?
I assume this is what the FOM is referring to regarding the “approved outerwear/ black raincoat / weather coat”.
Like the above reply stated, if it’s a generic looking pea coat / trench coat, I don’t see the problem with purchasing my own choice of a similar looking black trench coat.
12-01-2019, 06:29 AM
#67
On Guard!
Joined APC: Mar 2019
Posts: 1,181
Originally Posted by fussydutchman
The M & H website looks like it was designed in 1997 and doesn’t have much on it. Can anyone post a picture of the M & H trench coat?
I assume this is what the FOM is referring to regarding the “approved outerwear/ black raincoat / weather coat”.
Like the above reply stated, if it’s a generic looking pea coat / trench coat, I don’t see the problem with purchasing my own choice of a similar looking black trench coat.
I assume this is what the FOM is referring to regarding the “approved outerwear/ black raincoat / weather coat”.
Like the above reply stated, if it’s a generic looking pea coat / trench coat, I don’t see the problem with purchasing my own choice of a similar looking black trench coat.
https://www.wallaceapparel.com/101
12-01-2019, 06:43 AM
#68
Gets Weekends Off
Joined APC: Jan 2018
Posts: 2,242
Originally Posted by fussydutchman
The M & H website looks like it was designed in 1997 and doesn’t have much on it. Can anyone post a picture of the M & H trench coat?
I assume this is what the FOM is referring to regarding the “approved outerwear/ black raincoat / weather coat”.
Like the above reply stated, if it’s a generic looking pea coat / trench coat, I don’t see the problem with purchasing my own choice of a similar looking black trench coat.
I assume this is what the FOM is referring to regarding the “approved outerwear/ black raincoat / weather coat”.
Like the above reply stated, if it’s a generic looking pea coat / trench coat, I don’t see the problem with purchasing my own choice of a similar looking black trench coat.
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