zaitcev: Все сообщения за 17 Июня 2017 года

zaitcev>> Там специально новую модификацию двигателя разработали, чтобы можно было одинаковые модуле делать как на Ангаре,

Старый> Нееее. Двигатель там форсировали чисто чтоб дожать ПН.

В каком-то смысле ты прав, инициатором программы было требование поднять ПН. Но когда двигатель стал доступен, перешли на полную модульность. Вот как это описано у Кайла (выделено мной):

"The three engines performed the first RS-68A launch on June 29, 2012, when Delta 360, a Delta 4-Heavy Upgrade, orbited the NROL-15 payload from Cape Canaveral. The engines produced a combined liftoff thrust of nearly 955.28 tonnes (2.1 million pounds), a roughly 6 percent increase from the previous RS-68 engine thrust. A post-launch press release noted that Pratt & Whitney Rocketdyne (PWR) had developed RS-68A specifically to be able to lift the NROL-15 payload. The new engine produced 318.43 tonnes of liftoff thrust and 361.52 tonnes of thrust in vacuum. RS-68A vacuum specific impulse was targeted for 414 seconds, about 6.5 seconds more than the RS-68 value.

The improved performance was expected to increase Delta 4 Heavy's performance by 8 to 13 percent, depending on orbit. RS-68A will be phased into the entire Delta 4 fleet starting in 2015. The new engine will allow all of the Medium configurations to use a standard Medium+(5,4) core, rather than cores tailor made for each type of strap on solid motor set up. As a result, most the Medium variants would see slight performance losses compared to their original versions, but the move would achieve program cost savings."

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