PPRuNe Forums - View Single Post - Takeoff Performance Data
View Single Post
Old 31st August 2008 | 13:44
  #7 (permalink)  
Old Smokey
 
Joined: Jun 2004
Posts: 1,843
Likes: 0
From: Australia
sixfeetabove,

When calculating takeoff field length for a wet runway the most limiting factor is accelerate stop distance.

Are you sure?

I would agree with you that, at least for the aircraft that I do the Performance Engineering for, that is true in about 70% of cases. The other 30% or so are Accelerate-Go limited.

Consider this. Using wet runway data invariably leads to significantly lower V1 speeds, so far, so good, that V1 reduction is necessary to allow for the reduced stopping capability of the aircraft. As V1 is the Stop/Go speed, if then confronted with a "Go" situation, the aircraft must then accelerate from a lower V1 speed to Vr, and this will use SIGNIFICANTLY more runway than in a Dry Runway OEI Takeoff, 3 times the V1/Vr delta is common in work that I regularly do. From this, it is frequently found that Accelerate-Go is more limiting than Accelerate-Stop.(If it weren't for the reduced screen height to 15 ft, Accelerate-Go limits would then predominate over Accelerate-Stop limits).

Best Regards,

Old Smokey
Old Smokey is offline  
Reply