Post-update, I have to set N1 @ 80%+ to maintain 145 knots or so on approach with full flaps while following standard ILS G/S approaches in the 787. Prior to the update, I only needed ~62% N1.
I have no mods installed.
Weight different?
Weather/wind different?
CofG different?
Icing on?
All can affect required N1 to maintain speed.
Even if these aren’t the issue, which is correct; prior, or now, or somewhere in between?
The 787 is almost unflyable now with flaps 25/30.
Flap drag for (at least) 25° and 30° was already way too high with the previous version and now it has become even worse.
With full flaps you can barely maintain 130kts in level flight with max thrust at MLW 
CG doesn’t alter the speed at all (neither does the landing gear position)
All fair questions. But the weight is the same @ 440k. The CofG is the same @ 20% MAC. The weather is the same. Icing effects were turned off pre- and post-update. I will admit I don’t know what correct N1 is on the 787-10. But I do know 80-90% is too high (and far higher than other airliners which generally fall in the 40-60% N1 range on approach). I think PLZ104 is correct – it appears to be a flap drag issue because take-off and cruise (where there are less/no flaps) don’t seem to be an issue.
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Yup, I’ve had the exact same issue. Tried with multiple weight configurations. I had a calculated vref of 148 @ 25 flaps my last landing. I was established on final LOC/GS captured. . Gear down, spoilers armed. Basically Once I dropped flaps passed 10 degrees the engines started spooling REALLY high to just try and maintain vref. I was curious so I dropped flaps to landing (25) configuation and was getting airspeed too low warnings (N1 was basically maxed) Had to quickly retract flaps and landed OK with 10. Also agree takeoff is fine. Absolutely seems like a too much drag issue.
Thanks for the confirmation. I submitted a Zendesk request and hopefully some others will flag it so it gets fixed in a future update.
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Good news. Per Zendesk, this issue has been “solved” , as defined below:
- Solved: The bug report has been handled—our team has recorded the bug in our internal bug and issue tracker. Please note this does not mean you will see the bug fixed in the next update, but has been recorded and prioritized accordingly.
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