NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
10 inch Slide Rule vs. Pocket Calculator
From: Greg Rudzinski
Date: 2009 May 27, 19:01 -0700
From: Greg Rudzinski
Date: 2009 May 27, 19:01 -0700
The following is a simulated slide rule vs. pocket calculator altitude sight reduction comparison for declination 20 degrees north, meridian angle 25 degrees, and latitude 15 degrees north. A 10 inch K & E 4080-3 was used for slide calculations. A hp 9s scientific calculator was used for 9 digit comparison. Formula: Calculated Altitude = COSdec COSlat COSmeridian angle +/- SIN dec SIN lat The slide rule method uses Bowditch table #31 for inverse SIN. A magnifying glass x2 was used to improve scale resolution: (calculation time 3 minutes) .822 + .0885 = .9105 inverse SIN .9105 = 65� 35.0' (4.9' low) Trig pocket calculator calculation to 9 digits: (calculation time 90 seconds) .822631444 + .088521326 = .911152770 inverse SIN .911152770 = 65� 39.91' Trig pocket calculator to 3 digits: .823 + .089 = .912 inverse SIN .912 = 65� 47.0' (7.1' high) Preliminary Conclusion: A slide rule with magnifying glass is equal to 3 digit accuracy if Bowditch table #31 is used for inverse SIN. --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
