In the Blue Origin YouTube video Replay of New Shepard Mission 8 Livestream, "command engine start" is heard at T- 00:03, an audible "pop" can be heard at about T- 00:00.5 immediately followed by visible flames.

However, the apparent size of the hot exhaust and character of the sound continue to ramp until about T+ 00:06 and there is no vertical motion of the rocket until fully T+ 00:07.

Is there an almost 7 second "warm up" or ramping of New Shepard's BE-3 engine? Is this necessary function, or perhaps part of an exhaustive test (no pun intended) as this is a commercial space-tourism launch vehicle?

Video queued at T- 00:10

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    $\begingroup$ Generally, liquid-fuel engines need a few seconds to stabilize after ignition. The engine is also monitored and the hold-downs are only released if the engine operates nominally. $\endgroup$ – Hobbes Apr 30 '18 at 7:21
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    $\begingroup$ SSMEs had a ~6 second start sequence so this sounds reasonable to me. $\endgroup$ – Organic Marble Apr 30 '18 at 11:48
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    $\begingroup$ Liquid engines have a highly tuned, extremely critical order of startup sequence. I think there's at least one question on the site about it, let me look. $\endgroup$ – Organic Marble Apr 30 '18 at 11:56
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    $\begingroup$ space.stackexchange.com/questions/13095/… $\endgroup$ – Organic Marble Apr 30 '18 at 11:57
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    $\begingroup$ For SSME I have a graph of chamber pressure vs time during startup which is essentially thrust. If you'd like to ask that question.... $\endgroup$ – Organic Marble Apr 30 '18 at 12:25

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