Advantages
The expander cycle has a number of advantages over other designs:
- Low temperature. The advantage is that after they have turned gaseous, the fuels are usually near room temperature, and do very little or no damage to the turbine, allowing the engine to be reusable. In contrast Gas-generator or Staged combustion engines operate their turbines at high temperature.
- Tolerance. During the development of the RL10 engineers were worried that insulation foam mounted on the inside of the tank might break off and damage the engine. They tested this by putting loose foam in a fuel tank and running it through the engine. The RL10 chewed it up without problems or noticeable degradation in performance. Conventional gas-generators are in practice miniature rocket engines, with all the complexity that implies. Blocking even a small part of a gas generator can lead to a hot spot, which can cause violent loss of the engine. Using the engine bell as a 'gas generator' also makes it very tolerant of fuel contamination because of the wider fuel flow channels used.
- Inherent safety. Because a bell-type expander-cycle engine is thrust limited, it can easily be designed to withstand its maximum thrust conditions. In other engine types, a stuck fuel valve or similar problem can lead to engine thrust spiraling out of control due to unintended feedback systems. Other engine types require complex mechanical or electronic controllers to ensure this does not happen. Expander cycles are by design incapable of malfunctioning that way.
Some examples of an expander cycle engine are the Pratt & Whitney RL10 and RL60 and the Vinci engine for the future Ariane 5 ME .
Read more about this topic: Expander Cycle (rocket)
Famous quotes containing the word advantages:
“When the manipulations of childhood are a little larceny, they may grow and change with the child into qualities useful and admire in the grown-up world. When they are the futile struggle for love and concern and protection, they may become the warped and ruthless machinations of adults who seek in the advantages of power what they could never win as children.”
—Leontine Young (20th century)
“Can you conceive what it is to native-born American women citizens, accustomed to the advantages of our schools, our churches and the mingling of our social life, to ask over and over again for so simple a thing as that “we, the people,” should mean women as well as men; that our Constitution should mean exactly what it says?”
—Mary F. Eastman, U.S. suffragist. As quoted in History of Woman Suffrage, vol. 4 ch. 5, by Susan B. Anthony and Ida Husted Harper (1902)
“... there are no chains so galling as the chains of ignorance—no fetters so binding as those that bind the soul, and exclude it from the vast field of useful and scientific knowledge. O, had I received the advantages of early education, my ideas would, ere now, have expanded far and wide; but, alas! I possess nothing but moral capability—no teachings but the teachings of the Holy Spirit.”
—Maria Stewart (1803–1879)