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Date: Wed, 19 Jul 2006 11:13:50 -0400
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From: "Matt Hapgood" <matt.hapgood@alumni.duke.edu>
Subject: RE: [LML] Re: VistaNav
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Tom,

The Vista system uses the Motion Computing tablets.  I have owned two Motion
Computing tablets, and gone through four different hard drives in those
tablets.  I can tell you, from experience, that each of those hard drives
have crashed at 10,000 feet, +/- 1,000 feet.  That's right - some have
crashed at 9k and others at 11k.  I just returned from long trip in my 360
on Sunday (NC to California to NC), and the tablet crapped out before I got
to 10.5, just as I was getting into IMC...

I've also had a Toshiba tablet - it was good up to 18,000 (I never took it
higher).

There's a reason the Motion specs stink (compared to other tablets) - their
drive is MUCH more altitude sensitive.  It's a smaller drive than just about
any other notebook out there (1.8" vs. 2.5"?), and I guess that is one of
the trade-offs.

Matt

-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of
Marvin Kaye
Sent: Wednesday, July 19, 2006 4:23 AM
To: Lancair Mailing List
Subject: [LML] Re: VistaNav

Posted for "Tom Gourley" <tom.gourley@verizon.net>:

  "The 10,000 ft altitude limit of any of the Motion based systems is a
SERIOUS limitation"
  
  Matt,
  
  Good observation.  The specs for the system are a bit puzzling.  The
Inertial Navigation Unit, one of the two boxes that makes up a complete
system, has reasonable specs; up to 24,000 feet and operating temperature
from 32F to 105F.  The other box, essentially a tablet PC, is rated for up
to 10,000 feet and an operating temp range of 41F to 95F.  As you've pointed
out 10,000 feet is simply not adequate, even for us normally aspirated
pilots.  On the other hand, those specs are pretty typical for a notebook or
tablet PC.  Being a computer hardware guy myself I suspect that's simply
what the tablet PC manufacturer set as their requirement, validated the PCs
operation over that range and called it good.  Does this mean the tablet, or
Mobile Computing Platform as it's called, will stop working above 10,000
feet.  I doubt it.
  Would I bet my life on it.  Heck no!  I think Mercury needs to validate
operation at a higher altitude for this system to be taken seriously.  Many
times the altitude limitation for a computer is due to reduced cooling
efficiency at thelower air density.  I've seen specs on some computer
systems that derate the maximum operating temperature at higher altitudes.
Maybe they could do something similar with the VistaNav.
  
  Tom
  

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