Upper Stages
The upper stages of space launch vehicles are designed to operate at high altitude, and thus under little or no atmospheric pressure. This allows them to use lower pressure combustion chambers and still obtain near-optimum nozzle expansion ratios with nozzles of reasonable size. In many low pressure liquid rocket upper stage engines, such as the Aerojet AJ-10, propellants are pressure fed without need for complex turbomachinery. Low chamber pressures also generate lower heat transfer rates, which allow ablative or radiative cooling of the combustion chambers rather than more elaborate regenerative cooling.
Read more about this topic: Multistage Rocket
Famous quotes containing the words upper and/or stages:
“Surely you wouldn’t grudge the poor old man
Some humble way to save his self-respect.
He added, if you really care to know,
He meant to clear the upper pasture, too.”
—Robert Frost (1874–1963)
“But parents can be understanding and accept the more difficult stages as necessary times of growth for the child. Parents can appreciate the fact that these phases are not easy for the child to live through either; rapid growth times are hard on a child. Perhaps it’s a small comfort to know that the harder-to-live-with stages do alternate with the calmer times,so parents can count on getting periodic breaks.”
—Saf Lerman (20th century)