B747-200 V2 Speed

[FIRESYSOK]

Would someone give me a number for V2 of a B747-200 at approx 270 tonnes flap 20 and flap 10? (flap 20 is the normal takeoff, correct?) Thanks.

[Bae]

V2 Flaps 20: 152kts

V2 Flaps 10: 154kts

Either flaps 10 or 20 can be used, based on runway, obstacles, airline policy,....

greets.

[FIRESYSOK]

Wonderful, thanks for that. Not to be greedy, but I forgot to ask for Vref Flap 30 at the same weight. Thank you!!

[18-Wheeler]

Wonderful, thanks for that. Not to be greedy, but I forgot to ask for Vref Flap 30 at the same weight. Thank you!!

That's easy to work out ->
Vref = Mass/3 + 57.

[Junkflyer]

A quick gouge is 118 knots at 400,000 lbs. for flaps 30. Add 3 knots for each 20,000 lbs more-500,000 lbs.= 133 knots. Its not 100 % accurate, but pretty close-within a couple of knots.

[FIRESYSOK]

While we're on the subject, where exactly would one set the 5 white dial bugs for a flap 20 takeoff?

[Intruder]

V1, Vr, V2+40, V2+60, V2+80

[18-Wheeler]

While we're on the subject, where exactly would one set the 5 white dial bugs for a flap 20 takeoff?

Most only use four white bugs -
V1,VR, V2+40, and V2+80.

[Intruder]

Dunno 'bout "most"...

The "Frame" formed by the white bugs at V2+60 and V2+80 give a very good, quick visual reference for the Flaps1 and Flaps5 ranges when accelerating or decelerating.