Figuring Flex Temperature
I've heard the term many times in conjunction with airliners, and I understand what's happening (I think), but I've never been able to figure out what to actually set the flex temperature to.
The 146 is the first add on I've seen that comes with some info to help that, unfortunately I'm not understanding the charts and the manual snippet on flex is simply "follow the charts."
Does anyone have a layman's explanation for figuring flex temperature and/or an example?
I created a performance spreadsheet to help me calculate 146 take off and landing performance, including flex temps.
It's based on published Bae146 data, but not yet flight tested on the MSFS version of the 146. The spreadsheet is available from Flightsim. to. See the attached link:
@galeair very interesting, thanks for the link!
Any chance of getting CRJs or MD-82s to the list of aircraft?
@galeair So if I put in the temp and stuff for this and it comes out with a flex of 50, do I just set the OAT on the TMS to 50? It always stays at 'max 50' as well it seems?
I'm still flight testing, but that's my understanding. Flex temp is limited by engine type, so it looks as if the aircraft system and my spreadsheet agree that in the weather conditions you are taking off in the Flex temp is limited to 50. I'm still working out the. Just Flight Bae146 weights, and will be updating the spreadsheet within a few days.
No problem, but it will take me some time to assemble the correct data. I don't have access to any company performance tables, so have to trawl the Internet for information. I'm currently working on learning to operate the 146 and making adjustments to the weights in the spreadsheet to match the Just Flight ones. I will be pushing out an update as soon as I have achieved that.
@galeair Oh, hm... You can't set the TRef above like 46 though. Also very slow to get off the ground at that rate too.
Flex Temp calculations can be complex as there's lot of variables. But here's the basics.
MAX flex must be within 8% of calculated Ref power. So, if ref is 93%, the maximum amount of flex allowed is 85%. You don't necessarily go to Max flex, but somewhere in between depending on RWY, Weight etc. 85-88% is common.
If it's a hot day and you're heavy, it'll mean less flex is possible. Where as on a cold day, you can get away with a higher flex (lower N1).