Analysis of information sources in references of the Wikipedia article "Vulcan Centaur" in English language version.
Methane rocket has a lower density so we have a 5.4 meter design outside diameter, while drop back to the Atlas V size for the kerosene AR1 version.
It was a successful Cert flight, and now we're knee deep in finalizing certification
We chose LNG because it is highly efficient, low cost and widely available. Unlike kerosene, LNG can be used to self-pressurize its tank. Known as autogenous repressurization, this eliminates the need for costly and complex systems that draw on Earth's scarce helium reserves. LNG also possesses clean combustion characteristics even at low throttle, simplifying engine reuse compared to kerosene fuels.
table 10 of page 27
...a U.S. produced rocket engine under development for ULA's Vulcan launch vehicle is experiencing technical challenges related to the igniter and booster capabilities required and may not be qualified in time to support first launches beginning in 2021.
The first flight of Sierra Space's Dream Chaser to the International Space Station is now scheduled for no earlier than May 2025.
Methane rocket has a lower density so we have a 5.4 meter design outside diameter, while drop back to the Atlas V size for the kerosene AR1 version.
"ACES work has its fingerprints in our new version of Centaur, the Centaur 5 we're fielding with Vulcan. Those studies five, eight years ago certainly served us well, and it put us on a good path forward here for the evolution of our upper stages. We will continue to evolve our upper stage to meet the needs of the market going forward".
We chose LNG because it is highly efficient, low cost and widely available. Unlike kerosene, LNG can be used to self-pressurize its tank. Known as autogenous repressurization, this eliminates the need for costly and complex systems that draw on Earth's scarce helium reserves. LNG also possesses clean combustion characteristics even at low throttle, simplifying engine reuse compared to kerosene fuels.
"ACES work has its fingerprints in our new version of Centaur, the Centaur 5 we're fielding with Vulcan. Those studies five, eight years ago certainly served us well, and it put us on a good path forward here for the evolution of our upper stages. We will continue to evolve our upper stage to meet the needs of the market going forward".
...a U.S. produced rocket engine under development for ULA's Vulcan launch vehicle is experiencing technical challenges related to the igniter and booster capabilities required and may not be qualified in time to support first launches beginning in 2021.
table 10 of page 27