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Effect of wet runway on ASDR

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Effect of wet runway on ASDR

Old 21st Aug 2012, 12:28
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Effect of wet runway on ASDR

I have searched for this but have yet to get my head around the situation.

Compared to a dry ASDR the wet ASDR will be affected by reduced braking action requiring an increase in ASDR. However 2 factors that counteract this are that a wet V1 is typically used so the aircraft has less speed and energy to dissipate. Also, on a wet runway reverse thrust is permitted to be considered for stopping so would total braking action not be better on a wet runway than dry with wheel brakes only?

So does a wet runway make ASDR increase or decrease?
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Old 21st Aug 2012, 15:21
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Actually it can make it DECREASE thanks to the use of reverse thrust and lower screen height! THis is one of the reasons that software has a parameter restricting Wet takeoff weights "equal to" or "less than" dry takeoff weights.

Mutt
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Old 21st Aug 2012, 17:35
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I don't see no relation of a screen height n asdr except when u compare it with a todr or a tor, but your wet asdr = greater of the dry both engine, 1 engine or a wet asdr calculation.
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Old 21st Aug 2012, 21:22
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Paragon,

screen height is 15 ft for a wet runway, instead of 35 feet for dry. Mutt has it right. Note that he says "can", and not "will".
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Old 22nd Aug 2012, 17:58
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Screen height isn't relevant for ASDR, as you're not getting airborne.
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