Did you know : The introduction of the Sharklet on #A320 family resulted in a slight shift of the aircraft’s aerodynamic center by a few percent during take-off.
Since the trim settings prior to take-off are comparable for both Sharklet and non-Sharklet aircraft (as the green band remains the same), the elevators are automatically adjusted upwards (negative deflection) while on the ground. This adjustment is made to maintain consistent aircraft behavior at the moment of rotation, despite the change in the aerodynamic center.
The Sharklet caused a 4% MAC shift of the aerodynamic center towards the rear. This change results in an additional trim adjustment of about -0.7° (with the stabilizer moving upwards) relative to non-Sharklet aircraft.
Consequently, the trim adjustment on Sharklet aircraft is approximately 0.7° greater than that of non-Sharklet aircraft.
The purpose of the trim setting while on the ground is to ensure the correct pitch rate during rotation. However, this objective shifts during the climb phase, requiring the aircraft to be trimmed to maintain +1g.
After the aircraft ascends past 50 feet, the auto trim function is activated to meet this new requirement, adjusting for the change in the aerodynamic center between Sharklet and non-Sharklet aircraft.
This adjustment typically involves an additional downward deflection of approximately -0.7° (with the stabilizer moving upwards) for Sharklet aircraft in comparison to their non-Sharklet counterparts.
Author – Capt Arjun Singh
