Airbus performance
Joined: Apr 2007
Posts: 84
Likes: 0
From: Italy
re from captain87
"Could anyone kindly explain to me what TREF and Tmax reflect on airbus performance charts. I am a tad confused."
Hi bertie187,
in fact there are more complications for this topic.
Now the Airbus pilots compute all takeoff data (including Tflex) by using a computer program (Octopus etc.)
But this doesn't means that it's impossible to make a manual calculation ...
Now I shall try to explain the topic starting from giving you some brief notions ...
Tref is a flat rating temeperature based on the flat rated thrust used.
Tmax is a maximum certified temperature for takeoff calculated accordingly to the EGT limits (max thrust reduction of 25 %)
The optimization process (who gives Tflex) calculates the speeds which will produce the maximum takeoff weight or the maximum takeoff temperature for actual weight.
Tref and Tmax are clearly reported on the RTOW (Regulatory Takeoff Weight) charts which are calculated for a specific aircraft version and for a particular runway.
So Tref and Tmax are pre-calculated temperatures taken from the charts (1 Tref + Tmax for 1 chart for 1 aircraft version for 1 runway ).
By selecting the true OAT (Outside Air Temperature) on the RTOW chart, we obtain the MTOW and the max Vspeeds.
Doing it manually, this process would require a lot of time compared to the computer program calulation. Actually all data are calculated automatically by the computer and only a data crosscheck is required by the pilots.
There are more other things to add, but I linger to say this.
Regards
Hi bertie187,
in fact there are more complications for this topic.
Now the Airbus pilots compute all takeoff data (including Tflex) by using a computer program (Octopus etc.)
But this doesn't means that it's impossible to make a manual calculation ...
Now I shall try to explain the topic starting from giving you some brief notions ...
Tref is a flat rating temeperature based on the flat rated thrust used.
Tmax is a maximum certified temperature for takeoff calculated accordingly to the EGT limits (max thrust reduction of 25 %)
The optimization process (who gives Tflex) calculates the speeds which will produce the maximum takeoff weight or the maximum takeoff temperature for actual weight.
Tref and Tmax are clearly reported on the RTOW (Regulatory Takeoff Weight) charts which are calculated for a specific aircraft version and for a particular runway.
So Tref and Tmax are pre-calculated temperatures taken from the charts (1 Tref + Tmax for 1 chart for 1 aircraft version for 1 runway ).
By selecting the true OAT (Outside Air Temperature) on the RTOW chart, we obtain the MTOW and the max Vspeeds.
Doing it manually, this process would require a lot of time compared to the computer program calulation. Actually all data are calculated automatically by the computer and only a data crosscheck is required by the pilots.
There are more other things to add, but I linger to say this.
Regards
Last edited by captain87; 1st May 2007 at 10:21.
Joined: Sep 1999
Posts: 5,552
Likes: 25
From: ME
NOD,
Your engine is flat rated to ISA+15, this is your Tmin. Tmax is associated with the maximum rated thrust reduction limitation of 25%.
bertie187,
Google for "äirbus - getting to grips with aircraft performance". Or look in www.wingfiles.com
Mutt
Your engine is flat rated to ISA+15, this is your Tmin. Tmax is associated with the maximum rated thrust reduction limitation of 25%.
bertie187,
Google for "äirbus - getting to grips with aircraft performance". Or look in www.wingfiles.com
Mutt
