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Old 25th Feb 2010, 16:55   #1 (permalink)
 
Join Date: Apr 2006
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A320 wing anti-ice

in icing contitions would you turn wing anti-ice on right before take off?
it would give you 30 secs of anti-ice on take off roll, then it will operate when airborne. does take off performance cater for it?
thank you.
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Old 25th Feb 2010, 17:02   #2 (permalink)
 
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I think you will find that with the Slats deployed all or most of the hot air is vented and will not de-ice the leading edge. That is why its use is recommmended prior to extending that flaps/slats on approach, hence the reason for the note in the FCOM that extended flight in icing conditions with flaps extended `should be avoided`!

Last edited by Meikleour; 27th Feb 2010 at 20:00. Reason: addition
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Old 25th Feb 2010, 18:05   #3 (permalink)
 
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Does the wing TAI valve not close on selection of T/O power to reduce the bleed off-take from the engines?

As for venting, it all vents but only after its passed through the slat ducting, the hot air enters the system through a duct at the inbd end of the no.3 slat if memory serves me right.

Eng
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Old 25th Feb 2010, 19:06   #4 (permalink)
A4

Ut Sementem Feeceris
 
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If selected ON during taxi the system does a self check which opens and closes the WAI valve. If the valve is open for more than 30s on the ground it will bring up an ECAM caution.... no go. If you don't need it for takeoff you MUST switch it off! During the takeoff run the valves remain closed and if the system is left selected ON the valve opens as soon as the aircraft is airborne.

From memory there is about a two tonne penalty on TOW... but I've never used it for takeoff in 12 years.

A4
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Old 25th Feb 2010, 23:47   #5 (permalink)
 
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The wing AI is such a half-hearted system (outboard 3 slat sections) anyway I can't think why it would be so urgently needed for takeoff. Heating up your Type II/IV fluid is counter-productive. If inflight icing is expected to be so severe that 30 seconds of impact icing protection is significant to the safety of the operation - go back to bed.
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Old 26th Feb 2010, 05:28   #6 (permalink)
 
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haha cool.
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Old 27th Feb 2010, 21:47   #7 (permalink)
 
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Quote:
Originally Posted by Cardinal View Post
The wing AI is such a half-hearted system (outboard 3 slat sections) anyway I can't think why it would be so urgently needed for takeoff.
Or maybe the other side of the coin - if the cleanliness of those limited LE sections is so important that they bothered to install a WAI system just for them maybe it is vitally important to keep that part of the wing clear, rather than to conclude it can't be that important.

No designer goes to the trouble of anti-icing or de-icing something just for the fun of it - those systems are a major PITA for many people and have to "buy their way" into the design. usually on the basis they are serving a vital function.
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Old 27th Feb 2010, 22:01   #8 (permalink)
 
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Cardinal

With that kind of advice, I expect to be reading of your disciples on the front page of the news!

GF
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Old 28th Feb 2010, 13:57   #9 (permalink)
 
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What do you mean that the air is vented?

I think it doesn't matter where the hot air goes (and somewhere it has to go) as long as it heats the surfaces. if it is vented before it can do the heating... Who did design such a system?

In the performance charts you have to reduce weight, or reduce flex temp, when using it.
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Old 1st Mar 2010, 08:54   #10 (permalink)
 
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the reason it cant operate on ground (30 sec test cycle only) is to prevent overheat.
Dixon out.
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Old 1st Mar 2010, 20:29   #11 (permalink)
 
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WAI with SLATS extended: ISTR reading that the slats will still be anti/de-iced, however the slot will collect ice in prolonged flight in icing conditions, thus negating the point of the slats...
Can't find a reference, will keep searching.
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Old 2nd Mar 2010, 00:24   #12 (permalink)
 
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caveat: not based on information specific to the type

While its certainly possible that you'll get ice accumulation in the slots between slat and mainplane, another concern would be ice on flaps, if holding in a "non clean" configuration, which can also interfere with flap aerodynamics.

Also, in both cases, any ice may affect the mechanical operation of the devices. Similar considerations against prolonged use of spoilers in icing exist for some types. Not sure if anyone has an explicit prohibition, but extended gear down in icing probably also is unwise - imaging having built up a three inch double horn ice shape on gear legs and tyres...

Basically, aircraft are certified for flight into icing conditions assuming certain operating procedures, and doing other things than anticipated by the OEM may be unwise.
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