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FIRESYSOK
20th Jan 2008, 20:05
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
20th Jan 2008, 21:53
V2 Flaps 20: 152kts

V2 Flaps 10: 154kts

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

greets.

FIRESYSOK
20th Jan 2008, 22:46
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
20th Jan 2008, 23:29
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
21st Jan 2008, 03:40
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
21st Jan 2008, 04:01
While we're on the subject, where exactly would one set the 5 white dial bugs for a flap 20 takeoff?

Intruder
21st Jan 2008, 04:52
V1, Vr, V2+40, V2+60, V2+80

18-Wheeler
21st Jan 2008, 06:34
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
21st Jan 2008, 18:56
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.