NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brian Walton
Date: 2024 Dec 21, 07:02 -0800
Tide* up in knots, or decimated by kilometres? Traditional Wayfinding. Jets use Machmeters. Originally, to warn of shock waves, and control difficulties.
Mach 1, the speed of sound. Multiply by 6, you get true airspeed, eg M 0.8 = 6x8= 480, etc.
Running in to a DME, distance in miles covered in 66",x 100, = ground speed. eg, 4 miles x 100 = 400, etc. Compare with airspeed, you get wind. Radius of turn, on autopilot, 25° of bank, = Mach No x 10. eg M 0.8 = 8 miles, etc. If radar set 1° down, shows a storm centre, or mountain, at 60 miles, it is 1 mile (5,000') below. Start turn before 8 miles to avoid.
A 747 cruises at M .85, 500 kts. A 500 mile circle can be set on the glass map. When an airfield first shows, it will take 1 hour to get there, and burn 10 tons.
All done in the head.
* Today is Yuletide. Archaic. But you know the Sun's declination. With Flightradar24, I can lie in my boat and watch my son land his A380. Progress.
