Generally the greater the amount of ullage, the more potential that the wine has been exposed to harmful levels of oxidation.
As opposed to a fixed roof tank there is no vapor space (ullage) in the floating roof tank (except for very low liquid level situations).
Modern tanks are not fitted with ullage valves.
On the ground, the space between the top of the propellant load and the top of the tank is known as ullage space.
Ullage motors are typically very small; research shows that accelerations of the order 0.001 g are needed to avoid excessive gas intake.
There are standard descriptions used by wine merchants and auction houses for the fill levels (ullage levels) of wine.
This is because the pressure of the air bubble that is the ullage space rises and falls depending on temperature fluctuation.
The fourth stage then coasted until one hour and fifty seconds after launch, when it fired its ullage motors in preparation for ignition.
