NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: CN Aspects of Chichester's Tasman Crossing
From: Gary LaPook
Date: 2015 Nov 21, 08:34 +0000
From: Brian Walton <NoReply_Walton@fer3.com>
To: garylapook@pacbell.net
Sent: Wednesday, November 18, 2015 8:35 AM
Subject: [NavList] CN Aspects of Chichester's Tasman Crossing
From: Gary LaPook
Date: 2015 Nov 21, 08:34 +0000
No he didn't. he flew right past Lord Howe missing it by about 5 miles, it was hidden in a cloud. He finally spotted a rock pinnacle, "Ball's Pyramid," 18 miles beyond Lord Howe, got turned around and landed safely at lord Howe.
gl
From: Brian Walton <NoReply_Walton@fer3.com>
To: garylapook@pacbell.net
Sent: Wednesday, November 18, 2015 8:35 AM
Subject: [NavList] CN Aspects of Chichester's Tasman Crossing
Sextant.
Chichester tried a bubble sextant in his Moth,...
As it happens, at 200 ft, and a viz of 16 miles, semi-diameter, height of eye, and maybe refraction errors, pretty much cancel out. From 200 ft, a hill above 1000 ft high (Norfolk or Lord Howe) can be seen from 40 miles, viz permitting. As aircraft height increases, the height of eye correction will be off, but the increase in visible range of a hilltop will more than compensate for that. Chichester's altimeter was unreliable, but he reported seeing Lord Howe from 100 miles on his trip to Sydney. At jet altitudes, Mt Fuji, or Teide, can be seen from 200 miles. Flight at less than 140 knots is permitted 500 ft clear of people, buildings or structures. 500 ft vertically clear requires about 25 miles viz. Viz is crucial.
Brian Walton
