Re: [PSUBS-MAILIST] Re: Compass instruments

[David Buchner <buchner@wcta.net>]

On Saturday, Feb 22, 2003, at 11:55 US/Central, Alec Smyth wrote:

> I just re-read your message. My first response was in a bit of a rush, 
> as my wife was calling from downstairs that the house was flooding due 
> to the melting snow. But priorities are priorities, and I had to 
> finish my PSUBS message!

Besides -- what're you gonna do: Make the snow stop melting? You folks 
must be buying out all the shop-vacs and bilge pumps at the local 
hardware stores... No snow melting here today -- high of about 10.

> Anyway, between you and Cliff I'm really indebted for the research. 
> Imagine if I went out and spent a couple of thousand dollars on an 
> electric gyro only to find out what you just said about the 15 minute 
> duration! But my question is this... if you put a fluxgate in the 
> sail, it should work whether you're surfaced or submerged. What's the 
> need for having a gyro as well?

I was reading a couple of earlier messages in this thread, and was 
wondering whether this limitation on aircraft gyros is due to an 
expense issue, or a national security one -- as in, the technology for 
really solid fancy IMU's is controlled due to its usefulness in stuff 
like missile guidance. A relative of a relative of a friend works for a 
company that builds and tests stuff like that (laser gyros, is what I 
heard) and apparently part of the job of his lab is testing 
export-grade equipment to make sure it's _not too accurate_. Weird.

Apparently, I've missed part of this discussion... and am lazy. What is 
a fluxgate? Is that the name for the thingamagig the electronic compass 
in my car uses?

- - -
David
buchner@wcta.net
Osage, MN, USA