From: Michael Lorrey (retroman@tpk.net)
Date: Mon Jul 21 1997 - 17:39:26 MDT
Mark Grant wrote:
>
> On Thu, 17 Jul 1997, Michael Lorrey wrote:
>
> > I've never worked on a biplane, but I do know that business jets take a
> > good multiple of the maintenance time of small props planes. Rebuilding
> > a turbine engine is a lot tougher than a piston engine.
>
> Aha... this may explain our difference of opinion. You're talking purely
> about the amount of time required for maintenance when it's neccesary,
> whereas I'm talking about the frequency of maintenance and the frequency
> of failures.
>
> Sure, major maintenance on a more complex plane is going to be more
> complex and time-consuming, but from what I remember Bach's books he'd get
> up in the morning for an hour or two of maintenance on his biplane and
> even then every few weeks the engine would fail for some reason and he'd
> have to make an emergency landing. In comparison, he'd jump into his jet
> (T-38?) to fly between Florida and California with only a cursory
> preflight check; and it never crashed. In both cases they had major
> maintenance every once in a while, which would be much more work for the
> jet than the biplane.
This is an important point to include: Bach's biplane had no phased
service program established by the manufacturer, while the business jet
most certainly had a very extensive one, which went a long way toward
preventing most breakdowns due to wear/use. If Bach had a similar
program for the biplane, I would expect that he could expect a similar
reliability, if not better.
>
> So complexity may increase the effort required to maintain an aircraft,
> but has little bearing on reliability. And since much of that maintenance
> involves taking things off, looking at them, and putting them back on,
> built-in nanosensors could eliminate most of that.
It also includes replacing parts at timed intervals on a rigorous basis.
Changing fluids, greasing joints, replacing gaskets, o-rings, filters,
etc. testing circuits, replacing bulbs, switches and sensors as they
wear out. Monitoring insulation resistance, ground connections, etc.
Large components need to be replaced and rebuilt at timed intervals,
like generators, drive systems, pumps, motors, etc..
>
> > You can sheild a large part of it, but you are going to preserve the
> > areas of greatest sheilding for your crew, and with a mid course
> > turnaround, you've gotta have two sheilds, unless you can unhitch from
> > it and turn around and rehitch to the sheild at midcourse.
>
> You missed the point; the shield is just supposed to be a big hunk of junk
> which flies along in front of your ship and erodes when hit. But you're
> right; you would have problems holding it in place while braking. I guess
> you'd just rely on the exhaust from your engines vaporising anything small
> before it hit you; if you hit anything big you're dead anyway, shield or
> no shield.
If you are using a conventional reaction drive, you can expect the
exhaust to privide a bit of a shockwave, and you can just let the sheild
coast on ahead of you at high speed, so long as you are going to remain
on the same course. Otherwise, you'll have to have some near bussard
level magnetic systems to develop an EM shockwave in front.
>
> > Once they brought it back due to a broken toilet.
>
> Can you cite a mission number, because I don't remember that. I have vague
> memories of coming back early because of a blocked water dump valve, but
> that was a problem because the fuel cells need to dump water overboard,
> not because it affected the toilet.
That may have been it. I remember the pundits making jokes about the
mission being scrubbed because someone plugged the toilet.
>
> > The point is that things break more often than not with the shuttle,
> > even though it was custom built and is basically rebuilt after every
> > mission, and it only flies one week missions.
>
> Sure, but that's due to government designs, not an inherent problem with
> spacecraft (BTW, wasn't the last shuttle flight over two weeks?). And it
> still doesn't affect the fact that the majority of maintenance is fixed
> regardless of flight time. If a fuel cell breaks or a valve blocks up you
> just tear it out and fit a new one; that may require a few hours of
> overtime, but it's nothing compared to overhauling the engines.
Sure, I'll just do a couple 36 hour long spacewalks and change that fuel
cell in space, without a ground crew or equipment to support me. A multi
year voyage needs to carry its own entire maintenance departments with
it, with a stockpile of spare parts and consumables. Oh and I'll need a
collapsible space dock to help contain the mess while everything is
apart.
Here's an excercise to get some minimal idea of what I am talking about:
if you have a motorboat, take it, sufficient supplies, and tools and
parts out onto a body of water. Then proceed to dissasemble the engine
and totally rebuild it without returning to land and before your
supplies and patience runs out.
THink you can do it before getting washed onto rocks or swamped in
stormy seas? Wanna bet your life?
--
TANSTAAFL!!!
Michael Lorrey
------------------------------------------------------------
mailto:retroman@tpk.net Inventor of the Lorrey Drive
Agent Lorrey@ThePentagon.com
Silo_1013@ThePentagon.com http://www.tpk.net/~retroman/
Mikey's Animatronic Factory
My Own Nuclear Espionage Agency (MONEA)
MIKEYMAS(tm): The New Internet Holiday
Transhumans of New Hampshire (>HNH)
------------------------------------------------------------
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]+$y)%256;&S}$x=$y=0;for(unpack('C*',<>)){$x++;$y=($s[$x%=256]+$y)%256;
&S;print pack(C,$_^=$s[($s[$x]+$s[$y])%256])}sub S{@s[$x,$y]=@s[$y,$x]}
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