Need help to understand FLEX concept on MD 11 (FSX)

[Guest Tamadeez]

Yeah so I know a temperature must be entered in FLEX but don't you alreay enter a temperature in OAT on the DEP page in FMC. I've always thought the rwy length, OAT, slope/wind were factors that decided a T/O thrust or has it always been full thrust for T/O since I never changed FLEX. Also would the CI affect T/O or does that only apply after ACCEL ALT. Sorry if it's confusimg but can't explain any other way. One last question what does PACKS actually do seeing you have the choice for them to be off or on.

[FLEX1978 373]

Yeah so I know a temperature must be entered in FLEX but don't you alreay enter a temperature in OAT on the DEP page in FMC. I've always thought the rwy length, OAT, slope/wind were factors that decided a T/O thrust or has it always been full thrust for T/O since I never changed FLEX. Also would the CI affect T/O or does that only apply after ACCEL ALT. Sorry if it's confusimg but can't explain any other way. One last question what does PACKS actually do seeing you have the choice for them to be off or on.

You 'NEED' to read the rules around here before you post.Sign your real name, and post this in the MD11 forum.Do a search for FLEX on the MD11 forum, plenty of posts on the subject.Regarding packs - plenty of stuff on the net if you google http://en.wikipedia.org/wiki/Environmental_Control_System

[trisager 2]

Yeah so I know a temperature must be entered in FLEX but don't you alreay enter a temperature in OAT on the DEP page in FMC. I've always thought the rwy length, OAT, slope/wind were factors that decided a T/O thrust or has it always been full thrust for T/O since I never changed FLEX.

The flex temperature would be higher than OAT. If I understand the concept correctly, entering a flex TO temperature, e.g. 50C, causes the engines to produce the maximum thrust allowable if the OAT was 50C. The result is a thrust reduction, which improves engine lifetime.Whether or not this is permissible depends on runway length, aircraft weight, obstacle clearance an other factors. There are freeware tools and tables that can help you calculate the flex temperature (search these forums). There is also a very nice payware option called TOPCAT, with a built-in runway database and support for many different aircraft (the PMDG MD-11 and 747 among them).Which reminds me, I need to head over to the TOPCAT forum and ask them to implement support for the 747-800 :(

[downscc 1,327]

The underlying aircraft performance is identical to the 747-400X as this is just a 3D model addition.

Nothing to implement at TOPCAT

[trisager 2]

Nothing to implement at TOPCAT

Nothing much, I agree, but at the very minimum the aircraft type still needs to be selectable.

[Tabs 2,790]

That won't be accurate though, for now you're essentially going to be flying a 747-400 with a 747-8 visual model, that's what this expansion is. Performance will be exactly the same as the 400X.

[trisager 2]

Performance will be exactly the same as the 400X.

Yes, I understand that. I still want to be able to see "Boeing 747-800" in the aircraft type list in Topcat. Anyway, this is going way OT.