Sextant Adventure phase 103 Masters Degree Continues

[Dil52]

The Sextant Lesson 103 for a Master’s degree in FS Sextant Navigation.

Thanks to Gunter's link we now know that this flight from Palmer Station to McMurdo Station is similar to Lincoln Ellsworth’s trans-Antarcticflight in 1938 from Dundee Island to Little America. Our course is slightly different since Palmer Station is more Southwest than Dundee Island.

The Challenge:

The planning and preparation for this flight has required considerable preflight navigation.
As most know, the wind direction in FS isgiven as a Magnetic not True direction.
We won't use "control Z" so the magnetic wind direction is of no use when flying and using pure Celestial Navigation. Everything must be converted just as we must convert True wind direction when figuring the WCA with the E6-B computer.

We’ll navigate strictly with the sextant.
The magnetic variation changes are quite erratic and the longitudinal lines are merely about7.8nm in the S80s.

We’ll determine the (true) wind direction and speed using thecalculator incorporated into the Sextant chart

We'll take star shots each hour to determine, by DR calculations, ourfuture EP from our present apparent position (AP). That sounds real difficultuntil you break it down.

First we calculate our IAS/TAS/GS in static conditions.
In this casein the C47 we’ll fly at 12,000' at an average speed of IAS=145/TAS=172/GS=172knots.

As example, If we find we’ve traveled a distance of 162nm in the past hour we know thatwe’ve been flying into a 10 knot headwind. It could be that it’s actually a 20 or 30 knot cross wind and that’s where the sextant wind calculator will be useful for determining the WCA. Each reading should help us update our ETE.
That’s simpley using DR from our AP to determine EP in one hour.

Preflight Navigation and Planning:

Flight Plan: NZ0B Palmer Station to NZIR McMurdo Station

NZ0B Lat/Lon: S64°45.29' W064°01.88'
Fix01 Lat/Lon: S67°18.03' W065°59.81'
Fix02 Lat/Lon: S69°59.85' W068°40.09'
Fix03 Lat/Lon: S72°38.58' W072°07.62'
Fix04 Lat/Lon: S75°09.93' W077°03.57'
Fix05 Lat/Lon: S77°35.30' W083°35.15'
Fix06 Lat/Lon: S79°50.40' W092°41.72'
Fix07 Lat/Lon: S81°29.03' W107°16.04'
Fix08 Lat/Lon: S82°34.78' W126°30.83'
Fix09 Lat/Lon: S82°45.06' W149°02.89'
Fix10 Lat/Lon: S81°37.25' W168°34.12'
Fix11 Lat/Lon: S79°59.65 E176°33.07'
NZIR Lat/Lon: S77°52.60' W166°33.82'

To eliminate any confusion we've compiled our true and magnetic heading changes between LOP readings, which are spaced at one hour intervals. (172nm in this case)

In FS, the winds direction is given in degrees magnetic.
Since we don’t want to cheat and use Ctrl Z we need to compute our WCA from our True heading.

When using the sextant W hot key the wind direction is in true degrees.
We can use our E6-B to compute the WCA. Then by using the formula,TC+/-WCA=TH(-E+W) VAR=MH(-E+W) Dev(0 in FS)=CH we'll get our actual Course Heading.

Rather than executing all the computations each time we take a reading we’ll do as Ellsworth and Noonan when planning flights and simply make a chart showing all these differences at a glance.

Magnetic Variation Chart
		leg
		heading	Mag	True	WCA
		change	Heading	heading
RW19	16.7	0	191	207.7
NZ0B	16.7		177	193.7
Fix 01	19.2	-2.5	175	194.2
Fix 02	23.1	-3.9	174	197.1
Fix 03	27.2	-4.1	174	201.2
Fix 04	32.3	-5.1	169	201.3
Fix 05	40.2	-7.9	164	204.2
Fix 06	49.6	-9.4	166	215.6
Fix 07	62.4	-12.8	154	216.4
Fix 08	84.2	-21.8	149	233.2
Fix 09	106	-21.8	158	264
Fix 10	125.3	-19.3	160	285.3
Fix 11	137.2	-11.9	167	304.2
NZ0B	145.8	-8.6	167	312.8
RW7	145.8	0	69	214.8
RW25	145.8	0	247	392.8
RW15	145.8	0	149	294.8
RW33	145.8	0	329	114.8

The flight:

Aircraft: 1940 USAAF C-47 EW 5 tanks for a total of 1604 Gal,9624lb. Cap.

Departure Time: Leaving Palmer Station 0900AM Local 1200 UT 28/08/2011

Weather forecast: Weather looks mostly clear with 42 knot winds217M/232T at cruise altitude of 12000’.

In static conditions (No wind, average temperature and pressure altitude) and flying at an IAS of140 knots at 12000 feet our TAS/GS shouldequal to 172 knots. On the flight plan we’ll space our reading LOPs at 172nm apart as mentioned above.


You can referenct this great tutorial:
In his sextant chart example NA08 (located in the dc3_bbsxa documentation) Dave Bitzer explains that, in order to use the W (wind)indicator on the sextant graph, we must know the coordinates of where we were 1 hour prior then:

1 Take a reading of two to three stars at present time ofcoordinates of 1 hour prior location.

2 Move the green dot from the center of the graph to where thestar shots cross

3 Observe the true wind direction and speed using the W “wind”hotkey.

It’s important to note that we if we change course more than 20 degrees in the past hour the wind calculator will not work properly and give us an erroneous calculation.


Attachment 47024
Since the RW at Palmer Station is pure Ice we step back to do our run-ups on the hard pack before easing onto the runway for TO. The Brakes are useless in the RW.

Attachment 47023
Since the fight plan In FS is rather strange looking Earth Google shows the actual flgiht plan more clearly.

The quick way to circumnavigate around the world.

dil

[Dil52]

The Flight:
Fix1
Attachment 47043
Celestial Navigation Data for 2011 Aug 29 at 12:00:00 UT
For Assumed Position:
Latitude S67 20.0
LongitudeW66 00.0
Almanac Data SUN Hc + 5 02.5 Zn 50.6
MOONHc +10 22.3 Zn 56.0



Celestial Navigation Data for 2011 Aug 25 at 13:17:00 UT
For Assumed Position: Latitude S64 45.0
Longitude W64 00.0
Fix2 14:00Z Lat/Lon:S69°59.85' W068°40.09'
Attachment 47044
Looks like we’re falling behind by 6 minutes
The shot indicates we’ve not reached our expected Latitude.
I corrected for Gyro drift and got a significant change indirection.
We’ll need to be more responsive to that and check the Gyros more often.


Fix3 15:00Z S72°38.58' W072°07.62'
Attachment 47042
Still slightly behind and below Fix3 but real close.

Attachment 47041
sun and moon
You may to be able to see the Moon just above an to the left of the Sun
They're pretty much in sync now at the end of the Month.
Interesting to note: FS2004 changed from Full to Waning Gibbous sometime since we started the flight Sunday 28th at 8:00AM local, 13:00Z.


Fix4 close enough
Attachment 47040


Fix 4 hour 4

flight 1/3 complete
To continue later

dil

[teson1]

Hey Dil,
Really looking forward how you'll fare, and where you'll end up.
With the magvar and continuous GC course changes, and with only the sun for guidance, and no terrain for pilotage until reaching the other side that's one hell of a navigation job ! :salute:
All the best!
Looking good so far !

[salt_air]

Hey Dil,
Really looking forward how you'll fare, and where you'll end up.
With the magvar and continuous GC course changes, and with only the sun for guidance, and no terrain for pilotage until reaching the other side that's one hell of a navigation job ! :salute:
All the best!
Looking good so far !

Yep ... pretty much ... what he said!!



Back on the mainland after an easy flight with a twist at the end.

I'm a post behind, but it's getting late for ol' folks ... I'll catch up tomorrow.



Thinking about a separate thread so yours will be more concentrated and easier to follow.

How's that sound Dil?

[Dil52]

Magnetic Variation Chart
		leg
	Mag	heading	Mag	True	WCA
	Var	change	Heading	heading
RW19	16.7	0	191	207.7
NZ0B	16.7		177	193.7
Fix 01	19.2	-2.5	175	194.2
Fix 02	23.1	-3.9	174	197.1
Fix 03	27.2	-4.1	174	201.2
Fix 04	32.3	-5.1	169	201.3
Fix 05	40.2	-7.9	164	204.2
Fix 06	49.6	-9.4	166	215.6
Fix 07	62.4	-12.8	154	216.4
Fix 08	84.2	-21.8	149	233.2
Fix 09	106	-21.8	158	264
Fix 10	125.3	-19.3	160	285.3
Fix 11	137.2	-11.9	167	304.2
NZIR	145.8	-8.6	167	312.8
RW7	145.8	0	69	214.8
RW25	145.8	0	247	392.8
RW15	145.8	0	149	294.8
RW33	145.8	0	329	114.8

Sorry about the chart. It's the first time I've attempted to post an excel to word to post. Obviously it doesn't work too good.
Next time I'll just do a screen shot. There were a couple of corrections that needed to be made.

Thanks Gunter and Salt,

So far it's not been too hard. I've had the Sun and the Moon, but they're pretty much in sync for the next few days. I'd have liked to do it about a week ago when there was more of an azimuth difference between the two.

So far the flight has been quite exciting. We've been lucky as the wind has cooperated.

Thanks to Salt I down loaded this 5 tank long range C-47 with all of the aerodynamic updates by none other than Dave Bitzer and Mark Beaumont, including the auto-lean and auto-rich mixture feature. This bird soars like an eagle in a soft spring breeze. I believe some of the fight to maintain course is due to gyro drift which wants to pull us south. With everything else going on correcting that sometimes eludes me.

Thanks Gunter for pointing out the Lincoln Ellsworth Transantarctica flight. Studying their calculations definately helped in figuring out and understanding the magnetic variation and deviation during the planning stages. I used it to set up the chart. I realize the mag var is built into the FS sextant but it still makes it nice having everything down on paper before hand. I even added the RWs at NZIR.

There are a couple RWs at NZWD where the aircraft just disappears underneath the mesh in my scenery so I chose NZIR instead.

will continue the flight tomorrow

dil

[salt_air]

New avatar Dil? .... may "swipe" the old one to use at FlightSim ... need to freshen that place up a little.



You probably have a grip on this already, but in the particularly LR Gooney, with so much weight in the fuselage, I would switch to aux tanks after attaining cruise to burn them off first.

The plane does a little better for me on approach and landing with the weight in the wings rather than in the center.

[Dil52]

New avatar Dil? .... may "swipe" the old one to use at FlightSim ... need to freshen that place up a little. .

Sounds good do you want me to send it to you?

You probably have a grip on this already, but in the particularly LR Gooney, with so much weight in the fuselage, I would switch to aux tanks after attaining cruise to burn them off first.

The plane does a little better for me on approach and landing with the weight in the wings rather than in the center.

Thanks for that advice. I'm using that tank first so it'll be empty soon perhaps about LOP 6 or 7

[Dil52]

Transantarctica Flight Continues

LOP(fix) 4 to LOP 9.........5 hours.

Attachment 47138
LOP6 Seems smooth



LOP7 We encountered a strong cross wind in the past hour as the Sun goes down below the horizon. The shot shows us 15nm south of LOP7 and we know from preliminary readings our heading needs to be 210M degrees just to maintain our present Lat


Attachment 47139
aurora australis


To LOP 8
We’recrossing longitude lines like they were speed bumps on the road. It’ll be niceto see the stars. The wind must have shifted or quit again. I just saw the Sun come back up and it’s now 19:45Z and we’re 45nm north of Lat S82° 34’. These rapid changes in magnetic variation are beginning to be more difficult to maintain position. Come on stars!

Attachment 47137
Ah the stars for 20:00Z LOP/Fix 8
ANTARES +25 16.8 100.9
FOMALHAU +2221.4 193.5
SIRIUS +21 31.5 309.3

We’re right on Lat and about 30nm short of Lon, I’ll take it in this wind.........approximately 10 minutes behind schedule.

20:15 heading of 188M with a MV of 85.3 is 273T

We need to maintain this Lat for awhile.


Attachment 47135
the lonest sun set I've ever encountered....5 hours now and keeping up with it nicely. The San and Moon azimuths haven't changed more than 2 degrees for 5 hours.






Attachment 47136
LOP9 S82°45.06' W149°02.89' Time to rest.



dil

[cputters]

Looks great Dil. You're up to the part I was really looking forward to. Following the never ending sun.

I wonder how effective the pilot heating actually would have been back in the day. I'd expect you'd still need all your woolies on regardless.

[salt_air]

Sounds good do you want me to send it to you?

sure ... I found one but it's too small

[Dil52]

sure ... I found one but it's too small

I tried to attach it to a PM but couldn't so here ya go!............

Attachment 47162

This IS you Salt!

I thoroughly believe you'll do this one justice.Now that's a pilot!

[Dil52]

Looks great Dil. You're up to the part I was really looking forward to. Following the never ending sun.

I wonder how effective the pilot heating actually would have been back in the day. I'd expect you'd still need all your woolies on regardless.

Thanks, Good to see you here!

Yes, it is truely incredible!
I'm right on the actual LOP of the Sun and pretty much keeping up with it.
If I drift too far north it pops up over the horizon and we loose star navigation.

How did you make out with the sexant install?
I'd sure like to see you using it.

I also have FSX, but the computer here struggles a bit with it so I'm very content with FS2004.

Perhaps when I get some time I'll see if I can load the sextant into one of the FSX planes and check out the differences.

dil

[cputters]

Thanks, Good to see you here!

Yes, it is truely incredible!
I'm right on the actual LOP of the Sun and pretty much keeping up with it.
If I drift too far north it pops up over the horizon and we loose star navigation.

How did you make out with the sexant install?
I'd sure like to see you using it.

I also have FSX, but the computer here struggles a bit with it so I'm very content with FS2004.

Perhaps when I get some time I'll see if I can load the sextant into one of the FSX planes and check out the differences.

dil

Nah, not well.

From everything I read, the sextant just won't run in FSX. The best I got was the horizontal lines. Even the blue arrows on the left only took your mark to +/- 3deg

Not to worry though. I'm still trying to learn by following the progress from you guys. It's very informative.

[salt_air]

Chris,


It would be worth it to grab a copy of FS9 ... not sure how available it is.

I have both but I spend most of my time in FS9 by choice.



The vast numbers of downloads that are available (free) for FS9 and the fact that they keep coming will have me running "old school" for a long time to come.



Just a thought ...

[cputters]

Not a bad thought either just quietly.

I can't believe how little there is available for FSX compared to FS9.

I'm guessing you'd get it for pretty cheap as well these days. Might look into it.

Cheers

Chris

[Dil52]

Remaining LOP’s

Fix09 Lat/Lon: S82°45.06' W149°02.89' (Present position) 21:00Z
Fix10 Lat/Lon: S81°37.25' W168°34.12' (172nm) 22:00Z ETE
Fix11 Lat/Lon: S79°59.65 E176°33.07' (172nm)23:00Z ETE
NZIR Lat/Lon: S77°52.60' W166°33.82'(171.6) 00:00z ETE
As we travel in a straight line past the pole we’reactually heading north now.

CelestialNavigation Data for 2011 Sep 1 at 21:30:00 UT

For Assumed Position:
Latitude S 81 35.0
Longitude W 168 35.0
MOON 9503.4 S15 33.8 +17 46.9 76.0
SIRIUS 20146.9 S16 43.8 +23 42.4 325.1
PEACOCK 35632.6 S56 41.8 +48 20.8 173.4
Attachment 47313
It's interesting to note that when taking offset readings the distances to center aren’t correct. I believe that the latitude the longitude readings are not giving a proper distances.

In the shot above we should be approximately 90nm from our ASSUMED POSITION however it ia showing 114nm to center. If we take a shot 5 or 10 minutes later the distance will decrease rapidly. The one only shot we're concerned with, of course, is always the LOP shot and especially the latitude shot, which in this case is PEACOCK at an Zn of 173.4.







CelestialNavigation Data for 2011 Sep 1 at 22:00:00 UT
ForAssumed Position:
Latitude S 81 35.0
Longitude W 168 35.0
MOON 102 16.5 S15 39.2 +18 52.6 68.7
SIRIUS 20918.2 S16 43.8 +23 01.0 317.3
PEACOCK 4 03.8 S56 41.8 +48 31.9 167.2
Attachment 47311 Attachment 47312
The Sun is now only -0° 09.0’ below the horizon and the Moon’s Hc is getting higher as well as we begin heading of more north in latitude. We’re actually traveling straight, and since we’ve passed the center of the South Pole the latitude is increasing.

We’requite happy with this shot. Perhaps we’re a bit above the latitude (red) a bitbehind (green and blue). We only have 171.6nm to go to NZIR…… pretty much righton schedule.





CelestialNavigation Data for 2011 Sep 1 at 23:00:00 UT
Fix11 Lat/Lon: S79°59.65 E176°33.07'
MOON 10216.5 S15 39.2 +16 56.8 84.0
ACAMAR 26602.2 S40 15.2 +40 47.7 268.8
PEACOCK 403.8 S56 41.8 +46 41.8 179.5 lat shot
Attachment 47310 Attachment 47316
We’ve actually gained on the azimuth of the Sun and the Moon by about 90 degrees.This has been the longest sunset and sunrise we’ve ever experienced.

I’ve discovered an interesting characteristic of the FS sextant. When our actual locaation is W179°(-179) degrees of ASSUMED POSITION we cannot read E179°(+179)degrees until we’ve actually crossed the Anti Meridian(Internation date Line). It does make sense when you think of it as trying to read a star that's 358 degrees of azimuth from us instead of 2 degrees.

In 34 or so minutes we’ll start a nice slow descent into NZIR or about 70nm out.

As the Sun comes up once again in a direction of 42 degrees true our LOP to locate NZIR will be 132/312T (+ 145) 97/277M



Celestial Navigation Data for 2011 Sep 1 at 00:00:00 UT
NZIR Lat/Lon: S77°52.60' W166°33.82'(171.6) 00:00z
SUN 17956.1 N 8 28.9 + 3 16.5 13.4
MOON 14431.4 S11 18.4 +19 04.0 51.4

Attachment 47315

Attachment 47314


This flight, more than any other I've experienced, has been a very interesting learning experience. It's sad that it has come to an end.

What I learned.

1. I learned that at when traveling east across the IDL we actually loose a day or jump ahead a day in time, which ever way you'd like to think of it. I went from the 28th to the 29th in an instant crossing the Anti Meridian .


2. I learned that the FS sextant can not read across the Date Line until we actually cross it. It's best to pre plan all sextant flights, expecially when you're flying close to the Poles and crossing the Internation date line.


3. I learned that when taxing on ice we need to turn with one engine off and to stop we need to turn both engines off.

It's best to have the magnetic runway headings predetermined when the magnetic variation is 145 degrees.

All runways in FS scenery are not what they seem. We actually flew below the surface of RW 15 at NZIR and landed on RW 7 instead.



I hope you've enjoyed traveling along with us on this most unusual flight across Antarctica.

It's time to head north to some warmer weather up around Chris's neighborhood then perhaps up to California to join in on the Bendix Race.
No jets or P-51 here!

We may fly Doolittle's B-25 Mitchell or a 40's version of the DC-3 as usual.

dil

[Dil52]

Not a bad thought either just quietly.

I can't believe how little there is available for FSX compared to FS9.

I'm guessing you'd get it for pretty cheap as well these days. Might look into it.

Cheers

Chris

Chris,

http://www.amazon.com/Microsoft-Flig.../dp/B000096L71

I don't know what shipping and handling would be for you, but this sounds good.

You may want to find out if it's actually the "canister edition" or soft cover as they all seem to post he same screen shot. I'm thinking of picking up another one myself at these prices just in case the present version's disk goes bad or something.


dil

[cputters]

Nice one Dil

Thanks for the link. I'm off to the States for a few weeks next week so I'll pick a copy up while I'm there. I still can't believe that a piece of software 7 years old trumps the newer package.

Ah well, it happens.

Chris

[Dil52]

Nice one Dil

Thanks for the link. I'm off to the States for a few weeks next week so I'll pick a copy up while I'm there. I still can't believe that a piece of software 7 years old trumps the newer package.

Ah well, it happens.

Chris

Thanks Chris,

I don't think you'll regret picking up FS2004, especially since you're interested in vintage aircraft and navigational methods from the past.

I've just arrived in Invercargill, New Zealand. The OAT is a balmy 5° C
It was nice to set the gear down on real terra firma for a change.


Enjoy the trip to the USA and we'll be looking forward to seeing you again when you return home.

dil

[cputters]

I just tried installing my sextant files into a friends DC3 and I'm getting the same issues with FS9. (All arrows are now pointing to me for doing something wrong. )

The lon/lat arrows on the chart will only go as far as +/- 3deg This doesn't seem right.

I'm still getting the horizontal lines only, as I was in FSX.

I wonder if I have a corrupted file or something.

edit: scratch that - I replaced the back up file on the 1940 panel of the RD41 and it works fine....hmmm.

Anywho, now I'll just have to wait for my copy to show. Can't wait to get started.

[Dil52]

Great to hear that Chris, !!!!

I was about to post some cfg samples, but it looks like you've got it now.

dil