PPRuNe Forums - View Single Post - Downward turning effect during crosswind takeoff roll
Old 14th Jan 2024, 02:04
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andmiz
 
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I had a briefing on this from Airbus flight test a few years ago.
At low speeds (< ~70kt) in high-bypass ratio engines and at high thrust, a yawing moment counteracts the natural weathercocking effect of the aircraft. The resulting downwind turning moment is overall smaller than the opposite upwind turning moment, with the downwind moments and upwind moments counteracting each other equally just below 70kt, and then beyond this speed, the upwind moment has an overall larger effect.
The phenomena were first noticed by Boeing during the 777 test campaign and was been observed by Airbus in their 350-900 testing, and then subsequently in the 320-NEO and 350-1000.

It can occur in any aircraft but is generally hidden by the upwind weathercocking effect.
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