> back when I first designed them in the late '80s. Bring the engines
> online at reduced thrust until you had reliable "buoyancy" - i.e.
> total thrust to 50% vehicle mass - and then throttle up from there.
> That part of the launch sequence goes:
>
> - Get clearance for departure from local tower
> - Captain give "Engines to idle" command
> - Bring engine thrust up to 50% of mass
> - Get arrival clearance from destination tower if SubOrbital
> - Captain gives "Up Ship!" command
> - "Boosting!" from Propulsion Engineer as you throttle up
> - Ship lifts from pad and leaps skyward
Sounds like fun - but horrendously fuel inefficient - if you were really
going to do it something like that, then all the to and from banter would
hopefully be computerised.
After all, even though it's done with clamps, that's what the STS does now.
The main engines fire and take the orbiter out in a big slow arc - about 1
metre maximum deflection, and then back again in a resonant arc with a
period of several seconds, still under full main engine
thrust. The computers are measuring thrust (and everything else) and just
waiting for the stack to swing back into vertical alignment.
If the (wholly automated) "captain" and tower are happy then as alignment
again comes right it's SRBs ignited and clamps away and .... you fall into
the sky.
I've always thought it must be one of the most exciting (so far) non lethal
moments available on earth when, occasionally, tower and captain decide it's
just not on and they instead shut down main engines and instead of falling
into the sky you are sitting on one of the larger chemical explosive devices
made by man.
Russell McMahon
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