Aerofly Airbus planes regarding its Flexible Temperature feature

1st Official Post

    Hey IPACS,

    I noticed that changing the FLEX temperature on the A350 doesn’t seem to affect takeoff thrust/acceleration like it should. Higher FLEX temps don’t reduce thrust enough, so the takeoff roll feels off.

    Maybe the FLEX logic could be adjusted so it affects acceleration and distance more realistically?

    For example, when I input +80 degrees Celsius FLEX into the MCDU it does not derate the thrust enough, instead it derates to about 90% thrust. Correct me if I’m wrong but shouldn’t a flex temp as high as +80 degrees significantly derate the thrust?

    Thanks!

    • Official Post

    We need more real world data to properly set how much the thrust target should change based on flex temp. If you find a cockpit video of the A350-1000 (not the -900 with different engines...) where they use a high flex temperature and another video with a low flx temp then we can estimate the thrust reduction more precisely.

    Regards,

    Jan

    I can get hold of the figures for the A350. Perhaps stating the obvious, but flex and derates are two separate things. Derates are Vmcg/Vmca limited, and you cant select TOGA in the event of an engine failure, each derate corresponds to a fixed % of max thrust avail able, 75% thrust is the max you can derate the engines . The derates are correct in the sim, but the corresponding Vspeeds are incorrect. (Simbrief is closer to real world figures for the weight varient.

    Max acceptable flex temp for the A350 in the sim is 80c (ISA conditions) this give you a thrust rating of 90%. Unlike Boeing, you can't combine flex/assumed temps with derates to get a further thrust reduction.

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    on this A350-1000 during takeoff the flex temp was set to +59 and the thrust derated to about 77-78% can’t make out what the OAT is tho