Date: Mon, 05 Jul 2004 19:43:25 -0600
From: Andrew Stagg <kastagg@shaw.ca>
Subject: RE: [FlyRotary] Re: Into the blue again :-)
In-reply-to: <list-243285@logan.com>
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message-id: <000001c462fa$a66d1810$6700a8c0@AndrewsToy>
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As a general case, older hard drives also rotate at between 1/2 and 1/3 =
the
speed of today's and may be using a larger platter (further reducing the
relative speed of the platter under the head).  Both of these factors =
will
reduce the ability of the platter to suck the head down while it is =
spinning
and require that the drive be able to operate with a greater gap between =
the
platter and the drive.   In addition, they probably have a lower data
density on the platter itself providing a greater amount of redundancy =
of
'signal' to the head when it is reading from the platter. =20

Without knowing what the actual drives being compared are, I can't state
that these are definite factors but the generalization for the =
technology
based on age are valid.

Andrew

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Ralph Reed
Sent: July 5, 2004 6:33 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Into the blue again :-)


  The hard drive is "sealed" but it probably has a tiny hole some where =
just
like an eustation tube. That would prevent the deformation.  The older =
one
probably works to a higher altitude because the gap between head and the
disk surface is greater. I  have been told that this actually has to do =
with
the  airfoil on the head. As the platter spins up to speed the head =
drops
down on its cushion of air.


  ----- Original Message -----
  From: "Haywire" <haywire@telus.net>
  To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
  Sent: Monday, July 05, 2004 12:16 AM
  Subject: [FlyRotary] Re: Into the blue again :-)


  > > All hard drives have a spinning platter with a read/write head =
riding
a
  > > cushion of air just above it.  Go to 10,300' and there isn't much =
of a
  > > cushion left.  The head will fall into the platter turning at 7500 =
or
  > > 10000 rpm.  I think you'll be lucky if the drive ever works again.
  > >
  >
  > Hi Ernest;
  > Another theory I heard is that the disc case is sealed so that at =
the
lower
  > pressure it deforms the case enough that the heads are no longer =
aligned
and
  > that by drilling a very small vent hole into the hard disc case this =
can
be
  > alleviated. No evidence to back it up but it is something to =
consider.
  > However, I ran the system recovery disc's and everything is working
again
  > although I lost allot of data, but I've been thinking for quite =
sometime
  > that I should reformat my drive anyway. I just wish that I'd gotten
around
  > to backing up more data.
  > Last night I loaded Jepp FlightMap onto this old Toshiba and I took =
this
  > flying today all the way up to 15,300' and had absolutely no =
problems at
  > all. It worked very well and in some ways is more appropriate to the
task.
  > It only requires 12vdc versus the 19vdc for the Sony so can be wired
direct
  > to ships power rather than the inverter/power supply that I used to =
have
to
  > mess with. It's only real drawback is the screen is nowhere near as =
good
as
  > the Sony, however I'm likely going to add a small external screen in =
the
  > allowing this to be slid into it's storage slot under the panel. It
sounds
  > complicated but it's not really and it gives a great moving map =
display
  > along with a few thousand MP3's as it also inputs to the intercom.
  > I wrote down alot of performance figures during our flights today =
but I
  > forgot them in the plane so will post them tomorrow if I get in =
early
  > enough. After 11.1 hours flying this weekend I'm a little tired and
since
  > it's after midnight, I'll post in more detail tomorrow.
  > But I need to add that today was full of adventure for my plane as =
we
  > rolled it, looped it, flew it to 15,300' and did some rough field
landings
  > with never so much as a hiccup.
  > I'll try to answer other e-mails regarding fuel system & prop =
tomorrow.
  >
  > S. Todd Bartrim
  > Turbo 13B
  > RV-9endurance
  > C-FSTB
  > http://www3.telus.net/haywire/RV-9/C-FSTB.htm
  >
  >          "Whatever you vividly imagine, Ardently desire, Sincerely
believe
  > in, Enthusiastically act upon, Must inevitably come to pass".
  >
  >
  > ---
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  >
  > >>  Homepage:  http://www.flyrotary.com/
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