Re: SpaceX Falcon I Hold-Down Firing Scheduled

In article <1117015998.353049.309400@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
ceauke@xxxxxxxxx wrote:

> I'm a bit confused. This is actually the first time I hear that he's
> willing to accept some failures. The 'propaganda' on the spacex website
> suggested that this will be the most reliable rocket yet and they had
> this company who calulated the reliability etc. To be honest, I dont'
> know how you calculate your reliability when you haven't done a few
> flights. Surely if you can calculate it, you can just fix the problems.
>
> What will happen if the first launch fails? Will they not launch the
> falcon V then that early? What about future falcon I missions?
>
> Even worse, what happens if they succeed by luck and don't pic up some
> crucial problem?
>
> I can't decide which is worse. I really want to see them succeed and do
> the launch for bigelow etc and hear their massive anouncement for the
> future.

It's the difference between a design calculation and a test measurement.
Calculating that using five engines yields a more reliable launcher than
using one is not the same as determining the actual reliability of
multiple instances of a complete design.

And *nothing* is perfect the first time. There's *always* something you
forgot to simulate; or the models were inadequate in some way; or it was
designed perfectly but fabricated wrong; or it was designed and built
perfectly but someone forgets to open a valve in the ground equipment.
Only after multiple copies of the first iteration or two of the design
has been tested a while do you have a realistic hope of having found and
fixed the significant problems. Of course lunchers are so expensive
that you don't get to make many failure-driven iterations of their
designs.
.

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