Another fun fact: you can replace the need for ullage acceleration with a Propellant Management Device that uses surface tension among other things to hold prop

Another fun fact: you can replace the need for ullage acceleration with a Propellant Management Device that uses surface tension among other things to hold propellant enough to fuel an impulse that will settle the rest of the tank. http://www.pmdtechnology.com/Index.html http://www.pmdtechnology.com/Index.html For very low accelerations, they can even draw propellant "upwards" against the acceleration.