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Gary,

Thank you very much.  My questions are answered.  The only drawback is that 
this more-or-less closes the conversation!

Regards,

Fred Hebard
mbiew@comcast.net



On Nov 21, 2014, at 1:46 PM, Gary LaPook wrote:

> 
> From: Gary LaPook 
> To: garylapook---.net 
> Sent: Friday, November 21, 2014 10:26 AM
> Subject: [NavList] Re: Early methods of air navigation
> 
> See my prior postings:
> 
> Precision astrolabe, bubble sextant development
> 
> 
> Missing pages 192 and 193.
> 
> http://www.fer3.com/arc/imgx/Bubble-sextants-Precision-Astrolabe.pdf
> 
> http://fer3.com/arc/imgx/sextants.pdf
> 
> page 193
> 
> http://fer3.com/arc/img/111880.img_4663.jpg
> 
> page 192
> 
> http://fer3.com/arc/img/111880.img_4664.jpg
> 
> 
> 
> http://fer3.com/arc/img/111884.img_4666.jpg
> 
> http://fer3.com/arc/img/111884.img_4665.jpg
> 
> gl
> 
> 
> 
> 
> From: Fred Hebard 
> To: garylapook---.net 
> Sent: Friday, November 21, 2014 9:21 AM
> Subject: [NavList] Early methods of air navigation
> 
> The discussion of the Brown-Nassau CN Plotter brought to mind the following 
question. What methods did the early pioneers of trans-Atlantic
>  flight use for navigation, such as Alcock and Brown?  Brown was the 
navigator on that flight.  They made landfall near their intended 
destination.  Running down a line of latitude would be a clear choice, but 
how measure the latitude?  They flew at low elevations, so perhaps using the 
actual horizon?  Dip scales as the square root of elevation.  The error for 
being 50 feet off in elevation is less than two minutes of arc at 200 feet.  
In contrast, Admiral Coutinho installed levels on his Plath in 1919.  Had the 
British?  Then there is RDF, which was available in the U.S. by the Point 
Honda disaster.
> 
> Those are some guesses.  What does the documentary evidence say?
> 
> Thanks.
> 
> Fred Hebard
> mbiew---.net
> 
> 
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