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Old 19th Jun 2001, 10:09
  #18 (permalink)  
Zeke
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Unhappy

Mutt is 100% correct with regard to the use of Boeing logic to Airbus performance, Boeing performance is based around the balanced field model, Airbus optimizes EVERYTHING. You cannot compare one to another.

Many people do not realize that the definition of V1, and takeoff performance has changed, the old school of thought does not apply. The Flight Safety Foundation published a comprehensive article on this subject, it is online here at FSF web site (PDF document)

A summary of the article is as follows ....

<font face="Verdana, Arial, Helvetica" size="2">Recent revisions of the U.S. Federal Aviation Regulations and the European Joint Aviation Requirements redefine V1 as the maximum airspeed at which a flight crew must take the first action to safely reject a takeoff. Other revisions change the method of compensating for the time required by pilots to take action to reject a takeoff; require accelerate-stop data based on airplanes with fully worn brakes; and require wet-runway takeoff-performance data in airplane flight manuals.</font>
fernando

<font face="Verdana, Arial, Helvetica" size="2">Zeke, you mentioned a correction factor on item 3 that you get from a table, what are they based on?</font>
Quoting the same manual again (A320)

<font face="Verdana, Arial, Helvetica" size="2">Temperature Corrections for FLEX takeoff

When using Flex temperature takeoff (assumed temperature reduced thrust) the following temperature corrections are made to account for QNH and Bleeds
  • High QNH Add 1ºC per 0.30 Inch above 29.92 Inches (no correction when airport pressure altitude is 0 ft or below).
  • Low QNH Subtract 1ºC per 0.10 Inch below 29.92 Inches.
  • Engine Anti-ice on Subtract 1ºC.
  • Total Anti-ice on Subtract 1ºC.
  • Engine Bleeds on Subtract 3ºC.

Compare the corrected Flex Temperature (CT), the engine flat rated temperature (TREF), and the Outside Air Temperature (OAT. If CT is higher than both TREF and OAT, then take CT as the Flex Temperature, otherwise no flex temperature takoff is allowed. Note, the maximum flex temperature allowed is ISA+45ºC </font>
4PON4PIN

What you may be thinking of the corrections to the full thrust takeoff....I don't like the way this is worded, should replace every instance of weight with mass.

<font face="Verdana, Arial, Helvetica" size="2">Weight Corrections for Full Thrust Takeoff

When using full thrust performance the following temperature corrections are made to account for QNH and Bleeds
  • High QNH Add 100 kg per 0.10 Inch above 29.92 Inches (no correction when airport pressure altitude is 0 ft or below)..
  • Low QNH Subtract 240 kg per 0.10 Inch below 29.92 Inches.
  • Engine Anti-ice on Subtract 300 kg.
  • Total Anti-ice on Subtract 800 kg.
  • Engine Bleeds on Subtract 2000 kg.
</font>
rodelu

Did some digging...my little book here shows Tref of 30 and Tmax of 50

[This message has been edited by Zeke (edited 25 June 2001).]