Re: Re: starship-design: What is safest?

[Kelly St <KellySt@aol.com>]

In a message dated 12/20/97 7:22:33 AM, TLG.van.der.Linden@tip.nl wrote:

>Hi Kelly,
>
>>>OK, so apparently certain increased chances of premature death are accepted
>>>by the public.
>>>Now all that we need to figure out is what mission has the highest risk. We
>>>all know each others visions (at least from those that have written
lately).
>>>I'd wish we'd a bit hard data.
>>
>>Two rules of thumb come to mind.
>>
>>1)
>>People will accept higher risk from things they are in control of, then
things
>>others control.  I.e. passengers worry more about the safety of airliners
then
>>cars.  Thou they are safer in the airliner, they are not in control.
>
>If a one-way mission would be launched the risks would be determined in
>advance just as with a two-way mission. If possible, both scenarios should
>have backup plans in case of major but not lethal failures.

I don't see how this relates to rule 1?

>>2)
>>In a system, to increse relyability:
>>  - Lower the stress and increase the tolerances (to wear or damage) of all
>>    parts.
>>  - The fewer things to break, the less likelyhood of failure.
>>  - The less time you use a system (past the initial break in period) the
less
>>    likelyhood of problems.
>>
>>So a simpler system with the least demands for precision and stress factors,
>>will last longer with less problems or repairs.  If you use such a system
for
>>a shorter period of time, its far less likely to fail.
>
>Ah I see, like a low stress, simple engine that has to be turned on for a
>year over a period of about 30 years... Sorry, the engines that we think are
>necessary don't look that simple to me, they have a lot of parts that need
>to work without a single failure (else KABOOM).

That would be one example.  By defintion the engines are going to be one of
the least used systems.

I can't see why you think the engines would be unusually complicated?
Certainly compared to a lot of other systems on the ship they have few moving
parts, few things to go wrong, and use simple LARGE structures to carry purly
electrical, structural, megnetic, and thermal loads.  They are the most like
major power plants here, which have unusually long service lives (usually 40
years of continuous operation) compared to more complex ship systems like
computers, sensors, shuttles, etc.


>>Does any of this help?
>
>Not really, data is what may help.

Sorry


>Timothy

Kelly