D L X wrote:rcair1 wrote:
So - the wake turbulence of an aircraft ahead of you will be below it's flight path and will not start till THEY rotate.
That means that, if your aircraft has the performance to do so, you can plan your takeoff to lift off before their lift off point and stay above their climb path.
How long does wake turbulence from a preceding aircraft last? (At least on or near the takeoff runway?)
longhauler wrote:There have been many accidents from rotating too soon ... starting with two Comet 1s!
It was learned from the two Comet accidents that while the aircraft CAN rotate early, the huge amount of drag increase caused may prevent the aircraft from accelerating to a flying speed. That is why we fly jet transport aircraft the way we do.
Sure, if one's Vr was say 150 knots and V2 of say 155 knots, you actually could lift the nose off the ground at around 120 ... but then you'd never see 150, or flight.
These were very lucky people indeed. Their biggest help here was probably the very capable low speed characteristics of the early B737 wing. They'd never get away with that in an NG!
longhauler wrote:These were very lucky people indeed. Their biggest help here was probably the very capable low speed characteristics of the early B737 wing. They'd never get away with that in an NG!
rcair1 wrote:So - in calm conditions, imagine 2 vortexes off the wings, rotating opposite directions, trending down and out from the flight path.
D L X wrote:rcair1 wrote:So - in calm conditions, imagine 2 vortexes off the wings, rotating opposite directions, trending down and out from the flight path.
Right, so in this case, the waking TK plane was actually crossing the path of the RAM taking off, about a kilometer down the runway. Those wake vortices are pushing away from that point. The left wake moving towards the RAM (causing a headwind?) and the right wake is moving in the same direction as the RAM, causing a tailwind should the RAM run into it. If this change of direction happened near the point that the RAM rotated, could that have caused the plane's air velocity to suddenly move from above Vr to below Vr?
N14AZ wrote:Thank you very much for your input as professional. Can you tell us which Comet accidents you are referring to?
Clipper101 wrote:Once I travelling in an A319 & there was a B744 taking off ahead of us, I noticed our A319 climb was very rapid & steep with the engines roar seemed as if they are giving every power they could. I gathered the pilot was trying to climb above the wake turbulence generated from the departing B744.
Still I do not understand for such smaller aircraft departing behind heavier ones why higher flap settings are not selected for takeoff to guarantee earlier rotation velocities?!
VirginFlyer wrote:With higher flap settings, you can become airborne at a lower speed, but you also reduce your angle of climb, so if the goal is to clear an obstacle (or in this case wake turbulence), climbing out with a higher flap setting can be counterproductive.
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