A340 Takeoff Performance
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A340 Takeoff Performance
I'm wondering about the A340's takeoff performance.
Firstly, are the CFM56-5C4s flat rated to 30°C? If that is the case, then what is the TO N1 at 30°C? I thought I read in a CX flight manual that max derate in the 340 is only 40°C, which would not surprise me. At FLEX 40°C, what N1 would you be looking at?
Could someone give an example of when temperature (eg. at FRA or SIN) starts to eat into MTOW - eg. at what temperature will you have to limit your TO weight (I realise that there are several parameters to take into account, let's say SIN 02R for example).
Finally, with takeoff speeds, what Vr speed would you be looking at MTOW with Flap 1, Flap 2 or Flap 3? What VS would you be looking in the second segment? (again, I realise several parameters can come into play here). What improvement in second segment performance do you get with Flap 1 over Flap 2? In climbing with Flap 1, do you still have the 12.5° nose up pitch as with Flap 2? Would 1500fpm be a fair climb rate after takeoff with Flap 2 at MTOW and 25°C?
The reason why I ask is that LH must be having an interesting time out of PDX & DEN with its 343 services to FRA. I had a jumpseat ride in the 343, and I now regret not asking enough questions. I often have to defend the 340 against many unsubstantiated assertions, and I'd just like to bolster my knowledge.
Cheers
Justin
Firstly, are the CFM56-5C4s flat rated to 30°C? If that is the case, then what is the TO N1 at 30°C? I thought I read in a CX flight manual that max derate in the 340 is only 40°C, which would not surprise me. At FLEX 40°C, what N1 would you be looking at?
Could someone give an example of when temperature (eg. at FRA or SIN) starts to eat into MTOW - eg. at what temperature will you have to limit your TO weight (I realise that there are several parameters to take into account, let's say SIN 02R for example).
Finally, with takeoff speeds, what Vr speed would you be looking at MTOW with Flap 1, Flap 2 or Flap 3? What VS would you be looking in the second segment? (again, I realise several parameters can come into play here). What improvement in second segment performance do you get with Flap 1 over Flap 2? In climbing with Flap 1, do you still have the 12.5° nose up pitch as with Flap 2? Would 1500fpm be a fair climb rate after takeoff with Flap 2 at MTOW and 25°C?
The reason why I ask is that LH must be having an interesting time out of PDX & DEN with its 343 services to FRA. I had a jumpseat ride in the 343, and I now regret not asking enough questions. I often have to defend the 340 against many unsubstantiated assertions, and I'd just like to bolster my knowledge.
Cheers
Justin
