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» Online Classroom   » Celestial Navigation   » Public Discussion of Cel Nav   » Running Fix with Star Pilot PC

   
Author Topic: Running Fix with Star Pilot PC
sholekamp


 - posted October 22, 2012 10:32 AM      Profile for sholekamp           Edit/Delete Post 
I spoke with David Burch about using “100 Problems in Celestial Navigation” by Leonard Grey (1992). In attempting to solve the Running Fix problem 11-6 on page 56 I get a significantly different answer. I entered the various “settings” as listed in the problem then entered the times and observations in the Sight Reduction link. When I plotted the course, my answer is approximately 40* 51.8’N and 133* 46.3’W the answer is 40* 25’N and 133* 25’W. From the course traveled in the problem, my answer is obviously wrong.
I am able to solve typical fix problems quite accurately, however, I have consistently not been able to solve problems which have the sightings, say, 2 or 3 hours apart that are looking for a running fix.
I would appreciate your help.
Steve

Capt Steve Miller


 - posted October 22, 2012 01:41 PM      Profile for Capt Steve Miller           Edit/Delete Post 
First, I would like to point out that you indicated you were trying to solve Leonard Grey Problem 11-6 as a running fix. That problem is not a running fix and it is not on page 56 it is on page 57.
Second, I finally deduced that you were working on problem 11-3 based on the posted answer that you quoted. I did work problem 11-3 with the SP-PC software and got the correct answer as posted in the book.
I am not sure what help you need so I will give some of the data I used:
1845 DR 40° 25.9' N 133° 29.1' W,
1954 DR 40° 30.1' N 133° 24.5' W

If you have specific questions please post them.

From: Starpath
sholekamp


 - posted October 24, 2012 08:30 AM      Profile for sholekamp           Edit/Delete Post 
Thanks for getting back to me. I apologize for putting down the wrong problem. I was indeed working on problem 11-3. I don't understand where you came up with the 1845 and 1954 data. Considering the course of 040* it seems logical that you would be at those points when making the observations, but how did you calculate at those points?
Capt Steve Miller


 - posted October 24, 2012 08:45 AM      Profile for Capt Steve Miller           Edit/Delete Post 
I started with the DR position at 1318 and went to the UPDATE DR section of the SP-PC. I ensured that the Speed and course were correct and inserted the 1845 time and hit the compute button which gave the DR position at 1845. Then I updated the DR and changed the time to 1954 and again hit the compute button to get the 1954 DR position. I wrote this down for reference later. Then I went back to the settings and changed the DR position to the 1845 DR and changed the DR time to 1845. Next, I did the Sight Reductions for the MOON (note these were UPPER LIMB sights). Once done with that I went back to the settings and changed the DR to the 1954 DR position and changed the DR time to 1954. I then did the Sight Reductions for the SUN, after which I did a Celestial Fix at 1954 by computation with all of the sights. The result was the same as the answer on the answers page in the book.
From: Starpath
sholekamp


 - posted October 25, 2012 05:08 AM      Profile for sholekamp           Edit/Delete Post 
Super! That worked. I appreciate your help. Is that procedure in the manual somewhere? I didn't find it as I was trying to solve the problems. Again, thanks for your help.


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