I should point out that the B-17 was not originally "designed" for only 100
landings, however it was built to last only 100 landings during the war
because of the high attrition rate.  The original design of the B-17 dates
back to the mid-1930s.

Kind regards,

Denys. . .

Denys Beauchemin
HICOMP
(800) 323-8863  (281) 288-7438         Fax: (281) 355-6879
denys at hicomp.com                             www.hicomp.com


-----Original Message-----
From:   Gary Sielaff [SMTP:[log in to unmask]]
Sent:   Thursday, May 10, 2001 12:30 PM
To:     [log in to unmask]
Subject:        Re: Value

Wirt,
Where did you get the information on the 100 takeoffs?
I'm just real curious and an Aviation enthusiast.

Gary (180 miles from Boeing) Sielaff
----- Original Message -----
From: "Wirt Atmar" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, May 10, 2001 10:18 AM
Subject: Re: [HP3000-L] Value


> Chuck writes:
>
> > The PC was designed to be cost effective and so its components are not
as
> >  rugged as those found in that HP3000 you paid 100 times as much for.
Also,
> >  how many of those HP3000 components have been replaced over the years?
>
> Chuck's point is well taken. One of the most important things to consider
in
> the design of any piece of equipment is the environment into which it is
to
> be placed. In the case of PC's, it's one of extremely rapid evolution,
and
> there's simply no reason to overbuild these devices. Moreover, there is
> expected to be no one present to work on these devices, debug them, and
> replace defective components.
>
> In that regard, I was reading the other day a fact that actually shocked
me
> when I first read it, but one that makes otherwise perfect sense: B-17's
were
> designed during WWII for only 100 takeoffs and landings. It was felt that
> building the machines for any greater duty cycle than that was merely
wasted
> effort.
>
> The reason for that design criterion was that mortality rates were so
high
> over Europe for American bomber crews that a crew who survived 25
missions
> over Germany were given rotation home and out of the war, but very few
ever
> made it. Indeed, the fact that the "Memphis Belle" was the first achieve
that
> status was the whole reason behind the recent, mostly true movie about
the
> "Belle."
>
> If 25 missions was unlikely to be survived, 100 mission survival was many
> sigmas out, essentially zero probability of survival. Moreover every part
of
> the B-17 was designed to be as simple and as easily replaced as it
possibly
> could be so that damaged aircraft could be canabalized and their parts
reused
> on other airframes.
>
> Nonetheless, the reliability and the ruggedness of the B-17's became
> legendary. Cheap and simple doesn't always mean poor quality.
>
> Wirt Atmar
>
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