Does the weight of an aircraft effect acceleration on a flat trajectory? Obviously the Earth is round making a truly flat trajectory impossible but I'm trying to simplify this. Example) Would an aircraft that weighs (Force*Mass) 10,000 Kg accelerate slower with an additional 5,000Kg of weight stored inside? I know the top speed is the same, it's the time to the top speed I'm after. The obvious answer is a resounding yes but sometimes the obvious answer is incorrect. THANK YOU!!!!!