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Automatic operation of wing anti-ice

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While the operation of engine anti-ice in the T7 seems rather straightforward and intuitive to me, the T7's wing anti-ice (in 'AUTO' mode) kinda puzzles me:

 

If WAI activates, it operates only for about one or two seconds just to switch off after that short period automatically. Isn't a system like that supposed to work during longer periods of time in order to affect any structural icing?

 

And just in case someone like ... myself will read my post  (you know what I mean: the 'RTFM' type of guy ... :P): I checked the documentation but didn't really find the decisive hint (yes, all the documentation - the pdf search function was my best friend ... but didn't quite delivered the answer. B))

 

Thanks for bothering!!!

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I've noticed the same behavior when I set it to ON during initial climb out a few days ago. It cycled on and off about 2 or 3 times then came on steady, all while the tat was around 6 degrees.

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Cant help much here I am afraid :-(

 

12 years on the 777 and I have yet to see the Wing Anti Ice become activated automatically!

Engine anti ice yes.....but wing not.

 

I was told the 777 is not really prone to pick up wing ice due to its (aerodynamic) design and Boeing initially intended to not equip the 777 with Wing Anti Ice equipment at all!

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Cant help much here I am afraid :-(

 

12 years on the 777 and I have yet to see the Wing Anti Ice become activated automatically!

Engine anti ice yes.....but wing not.

 

I was told the 777 is not really prone to pick up wing ice due to its (aerodynamic) design and Boeing initially intended to not equip the 777 with Wing Anti Ice equipment at all!

 

 

Thank you, Rob, for confirming that WAI is a rare occurrence on the T7. It's rather hard to trigger in FSX; it takes some very special wx conditions for it to activate.

 

But when it engages, it's just a short "boost" of WAI, automatically switched off again after maybe 2 seconds. And neither the docs nor the web can really help explaining ...

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I've been leaving all knobs in auto thinking it would manage automatically.  So I should be turning on AI below 10C like every other plane? 

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I've been leaving all knobs in auto thinking it would manage automatically. So I should be turning on AI below 10C like every other plane?

Auto is fine, but according to the fcom, auto for the engine anti ice does not work on the ground, so it should be manually selected on until you are clear of icing conditions, and of course you know, wing anti ice does not work on the ground regardless of switch position.

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Could this not be a potential bug? Bryan is correct in saying WAI does not work on the ground. If you do select WAI it will turn on briefly just to do a self test, it will then automatically disengage.

 

If icing conditions are setup in the sim, and the aircraft is airborne, wing anti ice should remain on.

 

Edit - Should also add that even if SAT is below 10c icing conditions doesn't necessarily exist, visible moisture also needs to exist, fog/rain/clouds/snow

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Could this not be a potential bug? (...)

 

 

Like in : "WAI in the air is mistakenly modelled in the same way as WAI on the ground is supposed to work?"

 

Sounds plausible to me, Rob ...

 

 

 

@Ryan:

Can we get a ground/air switch, pls.?   :P

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Like in : "WAI in the air is mistakenly modelled in the same way as WAI on the ground is supposed to work?"

 

Sounds plausible to me, Rob ...

 

 

 

@Ryan:

Can we get a ground/air switch, pls.? :P

Yes possibly... Then again, perhaps the system also does a self test in auto whilst airborn if no true icing conditions are detected.

 

Have you tried setting the sim up in freezing rain? Put the aircraft in a holding pattern at low altitude, set heavy rain and SAT to something like -5, see what happens in auto whilst the aircraft is in a clean config

 

Regards

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Bug or no bug?!?

 

It starts with a period of ice accumulation ("ice weight" in FS Captain) with WAI off:

 

 

 

Next is a brief activation of WAI. You hardly notice the arrow indicator changing to green; it's almost "just" the valve indication (different for the EAI):

 

 

 

Now, that's really interesting: That very short period of WAI hardly having been on is enough for FS Captain to reset its "ice weight" to zero (and to start accumulating ice all over again):

 

 

 

FS Captain indicates that "WAI on" time is "sufficiently" modelled on the T7 - is this brief activation of WAI a bug at all???

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Interesting,

 

That CDU is provided by FS Captain?

Does it replace the 777 CDU completely?

 

I will have a look later today at wing anti ice here and see what is does.

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Interesting,

That CDU is provided by FS Captain?

Does it replace the 777 CDU completely?

I will have a look later today at wing anti ice here and see what is does.

No, the CDU just adds additional functions like ACARS and whole bunch of stuff. The addon is designed as a generic CDU. Check out the fscaptain website, they add quite a lot to the sim that enhances the realism.

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 If WAI activates, it operates only for about one or two seconds just to switch off after that short period automatically. Isn't a system like that supposed to work during longer periods of time in order to affect any structural

I looked into the (official) Computer Based Training we have. All is sais in there is:

 

Two fuselage side mounted Anti ice probes are mounted on the nose.

If a probe picks up ice, both probes will heat up in order to de-ice.

This is called an icing cycle.

 

Engine Anti ice is activated soon after ice is detected.

Wing anti ice is activated after several cycles! (so the probe must pick up ice again and again for the wing anti ice system to activate)

(We are talking Auto mode ofcourse!)

 

Once Engine and/or Wing anti icing is automatically switched on, the detection system does not stop detecting!

The probes keep going through their icing cycles and both Engine and Wing anti ice are not turned off untill no more ice is detected for several minutes (I dont know how many minutes).

 

 

So, yes it is supposed to work longer than just a few seconds!

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The probe oscillates at a certain frequency, when ice builds the extra weight changes this frequency and indicates that ice has accumulated, then the WAI is activated. It must use this as its reference for the activation and de activation.

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Ok guys I got some concrete info via the AMM (not my words) -----

 

2x ice detectors vibrate at approx 40,000Hz, and these will vibrate at a lower frequency when they collect ice. A heater turns on when the probe vibrates less than 39,867Hz. The heater stays on until the probe vibration returns to its usual value or the heater operates for 25 seconds. The usual time that the heater is on is 5 - 7 seconds, but if the heater is on for 25 seconds, the heater turns off and a fault condition is latched.

 

The detector has control logic that counts the number of heater on to off cycles.

 

If there are two or more cycles, and the airplane is in the air, the ice detector gives an engine icing signal to the ACIPS (Airfoil and Cowl Ice Protection System). The detector also gives an engine icing signal if the airplane is in the air and the heater is on for 15 seconds or more.

 

If there are ten cycles and the airplane is in the air, the detector gives a wing icing signal to the ACIPS.

 

The icing signals stay on until any of these conditions occur:

No ice for more than 3 minutes

The airplane is on the ground

The heater is on for 25 seconds.

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Good stuff :-)

 

So Wing anti ice should stay on for at least 3min (after those 10 cycles and then no further detection).

 

In the mean time I have been try to accumulate ice with the PMDG.

 

I have tried at around 0C and up to -10 ground temps.

Resulting in TAT from +2 to -21C.

I have tried in Stratus clouds, in Cumulus and CB.

I have tried in Moderate and heavy rain and snow.

No Ice.

I have turned off window heat...also no ice on windows.

 

You guys sure ice can be simulated in FSX?

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At FL300 over Canada SAT -56 TAT -26 above and below some cirrus, I turned on the AWI and L & R engine AI. The swithches stayed on never going back to auto. After 33 minutes I turned the switches off.

 

Michael Cubine

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Thanks all! Your references give me quite some insight.

 

I could create icing with

- Active Sky Evolution and searching for areas with CB

- and with the default thunderstorm wx theme, maybe additionally customizing/increasing the icing settings (towards 'severe').

 

Visual icing isn't included, neither in default FSX nor in the PMDG T7.

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Good stuff :-)

So Wing anti ice should stay on for at least 3min (after those 10 cycles and then no further detection).

In the mean time I have been try to accumulate ice with the PMDG.

I have tried at around 0C and up to -10 ground temps.

Resulting in TAT from +2 to -21C.

I have tried in Stratus clouds, in Cumulus and CB.

I have tried in Moderate and heavy rain and snow.

No Ice.

I have turned off window heat...also no ice on windows.

You guys sure ice can be simulated in FSX?

It is simulated, just very badly. The method for applying ice in FS9 and FSX is to increase the aircrafts gross weight, this happens very slowly, would hardly affect a Cessna let alone a heavy jet.

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(...) If you do select WAI it will turn on briefly just to do a self test, it will then automatically disengage.

 

(...)

 

 

One more note:

The ground self test doesn't seem to be modelled (at least I didn't notice any indications of a test in process), so, IMO, this self-test mistakenly running in the air doesn't quite explain my findings.

 

Anyhoo, FS Captain accumulating ice weight doesn't seem to be a problem with the current T7 build: Ice weight is reset by FS Captain in intervalls, so the ice can't do any harm.

 

I would still prefer for PMDG to "tweak" the de-icing period and/or change the de-icing logic.   B)

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Just like on the Airbus the ground test is done behind the scenes, you won't be notified on the flight deck. These aircraft do many self tests without notifying the flight crew.

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At FL300 over Canada SAT -56 TAT -26 above and below some cirrus, I turned on the AWI and L & R engine AI. The swithches stayed on never going back to auto. After 33 minutes I turned the switches off.

 

Michael Cubine

When you select ON....that is a manual setting. It will stay ON all day! The Automatic On/OFF mode is supposed to work with the switch/Switches on AUTO all the time.

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 When you select ON....that is a manual setting. It will stay ON all day! The Automatic On/OFF mode is supposed to work with the switch/Switches on AUTO all the time.

 

 

So what I tried didn't prove anything at all. I must have missed the point of the whole thread.

 

Thank you

Michael Cubine

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So what I tried didn't prove anything at all. I must have missed the point of the whole thread.

Thank you

Michael Cubine

Hey, happens to the best :-)

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