Is my Kasamba.com "expert" on crack? This question is not for school, it's something I'm doing on my own. About a year ago I was told on this board that in theory Mass has no effect on the top speed of an aircraft. Drag opposes thrust, Mass (weight) opposes Lift. Mass may slow down the acceleration of a plane but it has no effect on top speed. Top speed is limited by drag. Ok, so fast forward to 24 hours ago. I'm getting ready to do some testing of some variables and I break down and pay an "expert" on Kasamba.com $40 so that I'm absolutely sure I'm doing it right. Here is what I got... Max Velocity = Sqrt[(Thrust - Weight)/(.5*Fluid Density*Reference Area*Drag Coefficient) ] It's basically the drag equation with Weight added in. http://en.wikipedia.org/wiki/Drag_equation Weight limits the top speed of a theoretical aircraft? Is this guy right?