temp sensitivity

[tasev1 2]

Hi there. I am just wondering something. The 747 characteristics (climb performance, thrust setting, AoA, etc) are so sensitive to temperature, I have to disable real weather when I am flying at cruising altitudes. How come? I am not experiencing anything of the sort with any of my other addons (yes, they are all affected, but not to the degree of the 747). With real weather (even if the temp at FL360 is only -20 because of it), I can still get your 737, and also my other addons like the767 to still perform well. Any ideas?

[Guest D17S]

That's an interesting angle. Actually, maybe it's too warm up there.? Isn't colder better (ie, 'thicker' air). Am I thinking about this right? I (and others) have seen mysterious performance problems where the PMDG-400 would not maintain the FMC's 'MAX' calculated altitude with cruise power. Cruise just wasn't enough power to maintain airspeed and an extremely slow deceleration occurred. You go away for an hour (for a mid Atlantic) break and all of a sudden, all !!!! is breaking loose in the computer room. That stick shaker is enough to wake the dead! You rush back into the

[michal 44]

>even if the temp at FL360 is>only -20 because of itPerhaps you should start questioning this weather data. -20 at FL360 is a seriously out of whack temperature value. You should normally see something around -55 at this altitude. Turbine engine's operation will be seriously affected by the difference of 35 C.Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

[Check_Airman 3]

Is that -20 TAT or SAT?Paul

[xkoote 57]

It's most probably TAT which makes it a whole lot more beleivable.You have to remember that a plane's weight plays a huge role on it's maximum altitude. Just so you can compare, that both the 737 and the 747 on a MAX TO climb to it's FMS Max Altitude. One won't differ much from the other. Now notice the climb, turn and cruise perfomance of both. You'll notice that even though the 747 is a huge beast compared to the 737, that both have approximately the same performance margins. Why? Because the wing and engine combo for each plane is made exactly for it's weight class. But if that -20 is SAT at FL360, than no plane will be able to perform.Remeber also that if you use third party addons like FS)Meteo and AS6 you may have stumbled over a wind/pressure transition and that is why your 747 was performing sluggishly.Xander