puzzling flaps 10 on 737
While going through the FPPM, I was comparing various performance limited weights with different flap settings. Everything was as expected for each flap setting, except for flaps 10. There is a considerable decrease in airplane performance when using flaps 10. I'll present some data to verify this.
This is for takeoff field limit wt on dry runway with OAT 32 degrees, PA 4000', field length available 2880 meters, 20 kts HW and 1% slope. Aircraft is a 737-800W 24k.
The resulting weights along with various flap settings are as follows
Flaps 1 - 64.4 T
Flaps 5 - 66.3 T
Flaps 10 - 65.8 T
Flaps 15 - 67.2 T
Flaps 25 - 67.8 T
the story is the same for all weights with performance falling with flaps 10. Any ideas why this is so? Any aerodynamic reason?