On Mon, 3 Feb 2003 00:30:05 -0500 (EST), Henry Spencer
<[EMAIL PROTECTED]> wrote:

>Why should the big vehicle be significantly more complex, with lots more
>failure modes, than the small one? 

It shouldn't.  But it is.  I'm comparing Shuttle vs. Soyuz,
specifically.

>To be harsh and realistic, many cargos are worth more than a small crew. 
>In *commercial service*, why is lower reliability acceptable for a cargo
>hauler?  If you won't fly on it, I don't want my precious cargo on it.

In commercial service, it isn't.  These guys are in government
service.  Different rules apply.  You and I agree that they shouldn't
*be* in government service, but that's a separate debate.

>A reusable launcher likely will be worth more than crew and cargo put
>together.  If it is reliable enough to earn back the mortgage, it is
>reliable enough to carry a crew. 

That's fair.

>When we start building spaceships rather than "man-rating" artillery
>rockets, it will be worth including a crew if there is any significant
>chance that they can save vehicle and payload from problems that would
>otherwise cause them to be lost.  And there is.  Nobody flies unmanned
>cargo aircraft.  Data analysis after the first phase of X-15 flights
>indicated that an unmanned X-15 would have had a 30-40% loss rate, which
>matched actual experience with BOMARC and Atlas A almost exactly. 

Apples and oranges.  Weren't BOMARC and Atlas weapons, not intended
for multiple use?

Don't get me wrong.  I want to do manned ships.  But they're so much
bigger and more expensive.

-R

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