Sextant Connie Flight - Hobart (Tas) - Dunedin (NZ)

[Stearmandriver]

Haha I was going to say "GPS! Boo hiss!"

Just kidding though. I know the couple times I've had to deal with this kind of troubleshooting, once I finally solve it I'm so sick of the computer I don't even use the sim for a couple weeks lol. Glad you got your issues sorted.

[Adam_NZ]

Firstly - a HUGE thank you to Stearmandriver for his excellent video tutorial. It steps you through everything you need to know - enough to get cracking on an olde-worlde trip!

I did some local testing to get to grips with the gauge - then went on a 1,200nm jaunt across the Tasman from Auckland to Brisbane.

Departing Auckland:


Approaching Brisbane:




Sadly, as I have the framerate-killer ORBX YBBN, I got the inevitable OOM on finals ... but at least I crossed the Tasman and got a good visual of the airport - just as the sun was setting.

I've been using Google Earth (Pro) as my "chart" and, when testing, have been plotting my fixes as well as P3D lat/long equivalents taken at the same time. For some reason, I find the in-built gauge chart gives me much better accuracy (even though positioning the cursor is a bit crude) than when translating distances and angles to Google Earth via the method described in the video. Maybe it's a southern hemisphere thing.

Does anyone know where I can find online magnetic deviation corrections for *altitude*? I flew my NZAA-YBBN flight at 20,000ft and was wondering if I needed to apply tweaks to the standard declination/deviation(s).

The v6 gauge works flawlessly in P3D BTW folks.

Adam.

[TreeTops]

Hey Adam, nice new ride you have there.
After a couple of flights I came to the realisation of relaxing my expectations to 10-15 miles. It's nothing compared to 1000 miles plus flights.

[Adam_NZ]

Just a thought ... how exactly do I factor in magnetic deviation when using this gauge?

Let's say I'm on a 360° heading - as indicated by my aircraft compass (which I'm assuming is pointing to *magnetic north*) and my tables tell me the variation for that lat/lon position (and date) is 23°E. So ... is my true heading therefore 337°?

1) When enetering my azimuth course on the sextant/gauge, should I be using 360° or 337° if wanting to align to my course?

2) Same deal with Google Earth. I'm assuming it's "North" is Map North, so when drawing my lines should I be using 360° or 337°?

Or is the procedure to use un-corrected courses throughout and only apply the deviation when calculating the course to steer (plus or minus any corrections for wind)?

Adam.

[TreeTops]

Its only the magnetic compass on the plane that is not true heading. Most navigation is written down to be read in the cockpit as magnetic to remove the calculation hassle while flying. Everything else is measuring a true heading.

1) The sextant gauge will be measuring true heading.

2) Google Earth lines should be the same as the sextant headings, which are true headings.

NZ magnetic variation is 23E (east being -ve) so if the true heading is 360 the compass will read 337. ie 360 true - 23 var = 337 magnetic.
Over here in Perth its almost on the 0 mag var line, so if I head out into the Indian Ocean I will need to add the variation to get compass heading. 270E true + 5E var = 275E magnetic.

The procedure for using the sextant can be anything you want. First priority is to get 2 fixes as near to 90 degrees apart as possible for the greatest accuracy.
Second is to align your sextant shots with the aircraft to give to best measurement of speed and drift.

[Adam_NZ]

Many thanks, Trev - that's covered all my queries - all makes sense now!

Adam.