Henry Spencer wrote:
> Agreed. There is a difference, perhaps subtle but significant, between a
> mistake and a risky choice. The former is something that's definitely a
> bad idea, the latter has disadvantages but can nevertheless still be the
> appropriate course.
The difference between a mistake and a risky choice is often whether
you succeed. If you do, it was a risk ... of not it was a mistake.
> In this particular matter, you've got a three-way choice:
>
> 1. Pay what it costs to build two or (preferably) three tail numbers; or
> 2. Have reserves to cover unexpected downtime on the one and only; or
> 3. Accept that the project has a low probability of success, because your
> first significant accident will probably end it.
The cost involved in building two instead of one is only a little less
than twice the cost of building just one, but the cost of building
three is usually a small amount more than building two. Tooling costs,
etc are already covered. Planning to build three is essential to
ensure you can succeed in a risky venture, IMHO.
> The mistake is not building only one tail number, but kidding yourself
> about the inverse relation between margins and probability of success.
My experience in both aerospace and life is that the chances of success
are an inverse bell curve - if ther're not close to one they are
practically zero. There's little or no middle ground.
Michael
----------------------------------------------------------------------
Michael Wallis KF6SPF (408) 396-9037 [EMAIL PROTECTED]
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