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flyzigg

captain flight manual set

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just got the captain flight manual set , nice stuff. deep.

i need some help with vref .

what is vref 40 ?

i am familiar with the take off v speeds and the idea of v2 + xx

but i have never been familiar with vref 40 or vref 40 + 70 as is in the flight crew training manual.

appreciate the help. thanks

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Vref is the reference speed for the aircraft dependent upon weight and flap position. See, for example, FCOM1 at page 500 for the 737-600 table. I think it's based on 1.3 x stall speed.

 

If Vref 40 + 70 is specified (say for a no-flap landing), it means that you should work out what the Vref would ordinarily be for your current weight at flaps 40, and add 70 knots.

 

cheers,

 

jeff

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Vref 40 is actually 1.25x stall @40. I think it was because at flaps 40 approach, engines are in higher N1 and more responsive.

 

Vref is used normally as a basis for approach speed.

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