NavList:

Hanno,

I must refer all aviation matters to Gary LaPook. I did go up in a Cessna 172  as a passenger with Gary piloting a few years back and was able to do just ok using a navy MK V bubble octant from the front and back seat. No problems observing the Sun on all courses as I recall. The bubble in the octant moved way more than expected during the flights which is why averagers are necessary. Sight reduction was done real time with a Hp table and also a Palm Centro smart phone app. Both worked very well for getting instant LOP results. Multiple hand held GPS were used to grade observation performance. Had a chance to use an A-7 bubble octant on a commercial flight from Los Angeles to Orlando a couple years ago. It was a night flight. Stars, Planets, and the Moon were observed from a window seat. Plots and reductions done on the small tray table. Results were graded with a hand held GPS placed by the port. The 757 flew smooth presenting a steady bubble in the octant for the entire flight.

The recent Sun observations were done with a bubble octant from a boat dock in Channel Islands Harbor (not from a plane). The 8" circular slide rule seems to work good for the single 4 place Doniol haversine multiplication. No disappointment there. A 10" BN should get it done from any cockpit (plane or boat) to 3 minute precision. Francis will soon let us know.

Greg Rudzinski

 

From: Hanno Ix
Date: 2014 Dec 3, 12:50 -0800

Greg,

that's dapper!

The CHIC seems to show 4-digit multiplication results.While I don't think 4-digt results were a necessity in this flight it would nevertheless baffle me since you are using a circular slide rule with only 8" diameter I believe.

I assume you did both, the flying and the CelNav.There are some interesting issues from a pilots point of view:

Was there a particular technique to operate the sextant and the yoke simultaneously? That sounds tricky.

I suppose you planned for the direction of the field of view during flight so you could see the sun all the time, correct? Now, if you had to change direction to see the sun - say as much as 90 deg - that would cause  a possibly large deviation from a straight line between waypoints. How would one handle this?

While I am familiar with a glider's cockpit - very, very tight! - I have no idea about cockpit management in a Cessna. Therefore I wonder, how did you organize your cockpit for sextant, paperwork, maps and slide rule?

Assume Francis would succeed in making his BN and it would be sufficiently accurate. Maybe its size would be abt 12 by 12 . Could you accommodate a BN of this size?

H