Alternative magnetic compass

On Friday, 30 October 2015 00:00:20 UTC+2, Jonathan St. Cloud wrote:
My bird has a Butterfly and Lx 90XX with compass option, but I was still require to have a manual compass.

"There's a few varios with that capability." Most interesting point...so if you have an LX80XX or LX90XX you could add the LX Magnetic compass module (expensive) and meet the Flight Manual requirement. http://www.lxnav.com/accessories/compass.html

What other varios?

I ditched my old compass after getting Butterfly Vario as it has built-in compass. So far no one has grounded my glider, and it goes trough EASA ARC-colonoscopy every year.

On Friday, October 30, 2015 at 8:27:44 AM UTC+3, Jonathan St. Cloud wrote:
As for reciprocals, plus 2 minus 2, or or the reciprocal works for most headings. i.e., 180 +2 - 2 is 360. Doesn't work for every heading but works for most.

Huh? It works for everything if you don't mind subtracting 360 if the answer is over 360.

Otherwise it works for *exactly* half the possible headings (0 - 180) and +20, -200 works for the rest.

On Thursday, October 29, 2015 at 8:48:58 PM UTC-6, jfitch wrote:

The GPS system isn't a single point of failure, there are currently two fully operational systems, soon to be 3 and in a while longer 4.

Magnetic compasses were a great idea for 14th century explorers - not so much for 21st Century aircraft.

We need something better.

I was having fun with my comment about counting the GPS gadgets. Agreed that the iPhone uses GPS and GLONASS. I know that's not true with all devices; does anyone know if the receivers used for our soaring-specific stuff do?

That said, I did read that one chip company conducting tests last year when the entire GLONASS system went down for 11 hours reported that one of their receivers that tracked both systems "wandered significantly in its position reports" during that outage.

As for mountain peaks, you guys need to fly in the east and midwest where, on many days in the summer, you couldn't see peaks more than a few miles away in the haze even if they did rise from the cornfields and pastures.

I don't use my vertical card compass much anymore and probably wouldn't miss it much if it were gone. But it's nice to have on those occasions when, under stress, I prefer an AOGUIRCE (Always On Graphical User Interface Reciprocal Calculator Engine).

Chip Bearden
ASW 24 "JB"
U.S.A.

On Friday, October 30, 2015 at 6:26:52 PM UTC+3, wrote:
I was having fun with my comment about counting the GPS gadgets. Agreed that the iPhone uses GPS and GLONASS. I know that's not true with all devices; does anyone know if the receivers used for our soaring-specific stuff do?

I think you'll find that all reasonably recent phones can use both GLONASS and GPS. The Russian government made GLONASS compatibility a requirement of selling in Russia, and it's not worth making some with and some without. Samsung's first was the Galaxy S II, and Apple's first was the iPhone 4s. (both released roughly northern summer 2011)

I'd expect that everything else uses GPS chips made for phones now, as phones are so much higher manufacturing volume than everything else that their chips end up the cheapest.

Living in New Mexico, we're continually faced with GPS testing outages.
But then, we can routinely see for over 100 miles and the mountains make
pretty good landmarks! And yes, I carry a sectional chart in the
cockpit, though I don't recall the last time I looked at it, since I
have airport data included in the databases that feed my Streak/XCSoar.
But if both of my batteries fail, I can look at the chart.

On 10/29/2015 6:32 PM, wrote:
When you guys get finished counting up your electronics with triple redundant power supplies, keep in mind that you still have a single point of failu the GPS satellite system. I realize I'm ignoring phones that use the cell towers to triangulate your position but none of the whizzy soaring-specific gadgets have that capability, to my knowledge.

I've used a magnetic compass a LOT in nearly 3,000 hours of glider flying. Before GPS it was indispensable. I still refer to it occasionally for quick reciprocals (it's a vertical card). And it's nice to know that with it and my paper chart (yeah, how quaint), I could still get home. Of course, forget getting credit for the flight since the logger is worthless if the GPS system is taken down. Oh, well. It sits way forward on the glare shield and doesn't get in the way so that's where it will stay.

Chip Bearden
ASW 24 "JB"
U.S.A.

--
Dan, 5J

When I did my Gold Distance/Diamond Goal triangle out of TSA (Dallas,
Ft. Worth area), it was during the Yellowstone fire. Flight visibility
was probably less than 5 miles and altitude AGL was not that great,
either, nor did I have a GPS. I simply headed west (the direction
between the runway and the clubhouse) until I found the highway leading
to my first turn point and then, using the map to pinpoint my location
by ground reference, flew to the first turn point. I think I used the
compass to set a general heading towards the second turn point and then
used the map again to keep track of my position. There are enough
ground references in north central Texas to navigate by. Not so much in
the high plains of New Mexico. Without the mountains, I'd actually have
to use a compass to find my way back home!

On 10/30/2015 9:26 AM, wrote:
I was having fun with my comment about counting the GPS gadgets. Agreed that the iPhone uses GPS and GLONASS. I know that's not true with all devices; does anyone know if the receivers used for our soaring-specific stuff do?

That said, I did read that one chip company conducting tests last year when the entire GLONASS system went down for 11 hours reported that one of their receivers that tracked both systems "wandered significantly in its position reports" during that outage.

As for mountain peaks, you guys need to fly in the east and midwest where, on many days in the summer, you couldn't see peaks more than a few miles away in the haze even if they did rise from the cornfields and pastures.

I don't use my vertical card compass much anymore and probably wouldn't miss it much if it were gone. But it's nice to have on those occasions when, under stress, I prefer an AOGUIRCE (Always On Graphical User Interface Reciprocal Calculator Engine).

Chip Bearden
ASW 24 "JB"
U.S.A.

--
Dan, 5J

Years ago--OK, decades ago as a teenager--I was flying my first Chester, SC regional contest in a 1-26. I had finally made it to, IIRC, Monroe and headed out to Pageland. The big highway made it easy and I barely consulted the compass. That's good because it apparently wasn't working; it was at least 45 degrees off. I finally arrived at Pageland (in a 1-26 at the end of the day, the miles just crawled by) and slowly lost altitude searching for the airport. My crew had gone on from Monroe to Pageland (this was back in the day when most crews followed their pilots around the course) but their voices on the radio were getting curiously scratchier and weaker the closer our positions converged.

Finally, discouraged, bewildered, and frustrated, I turned final for a nice field not far out of town. There on the water tower was the name of the town: Marshville. That big highway was new enough that it wasn't on my sectional chart. The compass had been spot on all along. The scorer was a young Billy Hill and he had a great time poking good-natured fun at the embarrassed kid when I arrived back at the Chester airport that night.

I won't say I never doubted my compass again but whenever I did, it was always right. As festooned with electronics as my current cockpit is, I still occasionally glance at the compass just for reassurance, the same way I pull out my cardboard final glide calculator once in a while to do a sanity check on the flight computer's promises that I can make it in from afar.

Chip Bearden
ASW 24 "JB"
U.S.A.

I should also remind everyone that GPS-derived bearings only work when you are moving with respect to the ground. Just remember this if you're stationary or even moving backwards in wave.

Mike

On Friday, October 30, 2015 at 1:03:52 PM UTC-7, Mike the Strike wrote:
I should also remind everyone that GPS-derived bearings only work when you are moving with respect to the ground. Just remember this if you're stationary or even moving backwards in wave.

Mike

There are GPS compasses that do not depend on motion for operation. Doubt anyone has one in a glider though.