--- On Sat, 6/5/10, Andrew Glasbrenner glasbrenner@mindspring.com wrote:
From: Andrew Glasbrenner glasbrenner@mindspring.com Subject: [amsat-bb] Re: Falcon 9 video - moving early? To: vk1pe.peter@gmail.com, amsat-bb@amsat.org Received: Saturday, June 5, 2010, 4:57 PM SpaceX starts all nine engines and makes sure they are operating to spec before releasing the rocket from the pad. The shuttle does the same thing with the three shuttle engines before they light the solids.
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That's been the case even earlier as well. Listen to any of the countdowns for the Apollo lunar missions. The Saturn V's engines would ignite at about T-9 and take a few seconds to produce full thrust before lift-off at T = 0.
If I'm not mistaken, in the very early days, T (or, as it was originally called X) = 0 was when actual ignition occurred, so lift-off was 2 or 3 seconds later.
73s
Bernhard VA6BMJ @ DO33FL