Alternative magnetic compass

[benso...@gmail.com]

A sailplane's Flight Manual usually requires a magnetic compass (or an aviation compass)as minimum equipment. Well, panel space has become less available and you are seeing fewer sailplanes with panel or glare-shield mounted 2.25 Airpath C2xxx or PAI-700 aircraft specific compasses.

Anyone have a "point" to an off panel compass that might meet FAA scrunity? Unfortunately the Cook compass manufactured by COBB-SLATER Instruments Co. Ltd is no longer available. http://compassmuseum.com/aero/aero.htm#COOK

Probably, a magnetic compass is the last instrument used by a competition pilot. Most competition sailplanes have 3 or more separate GPS engines and it is very simple to have them on independent battery sources. What would be the "penalty" if your sailplane failed a FAA "courtesy" ramp inspection because it lacked a magnetic compass?

Does a F-35 Lighting II joint strike fighter has a magnetic compass?

[Dan Marotta]

A poor showing during a ramp inspection (we're not happy until you're not happy) would likely result in your aircraft being grounded until you show compliance.

I'll bet the F-35 has a "whiskey" compass and I'll further wager that the flight manual says something along the lines of, "Flying by use of the magnetic compass is an emergency procedure."  At least that's the way it was back in the '70s.

--
Dan, 5J

[JS]

If you're glider is registered as EXP, look for a PZL compass. Might fit in an odd "corner" of the panel.
Jim

[Dave Springford]

I sell a TSO'd compass that is similar to the PZL compass. The SIRS Navigator.

You can find it here:
http://www.foxonecorp.com/index.php/basic-flight-instruments/compass

Also have the standard Airpath and a panel mount SIRS compass as well. The Navigator is nice as a glareshield mount because it is smaller than the Airpath.

Typical mount in a glider involves removing the mounting arm and top plate from the compass and then screwing the compass to the instrument panel glareshield at the bottom. There is a slide on slide off "foot" at the bottom of the compas. This reduces the height of the unit by about 1/2 inch.


Dave Springford
www.foxonecorp.com

[SoaringXCellence]

In the US you might check your glider Type Data Certificate. The Libelle H301 does not require a compass unless you are intending to do cloud flying, which is, of course, not permitted in the US contests. (However it is still possible to have a glider certificate with instrument privileges, but I haven't figured out how to take the test!)

Mike

[SoaringXCellence]

Oops, I stand corrected, the TCDS for the Libelle requires a compass, HOWEVER, the pilot manual says that the compass is only required for cloud flying.

[ifee...@hotmail.com]

Sometimes the TCDS or AFM specify a certain make or model of compass so be sure to check that. In some cases those specs have been altered by a subsequent TN from the manufacturer giving guidance to the installation of additional equipment to allow for the possibility that the originally specified equipment may no longer be available (Schleicher for one has done this). God knows why but the manual for my ASW-15 says that if the compass cannot be corrected to within acceptable limits when installed in the panel, it can be installed on the cockpit sidewall. In Canada, flight rules require a magnetic compass even if the TCDS and manual AND airworthiness requirements for pure glider don't. The regulatory requirement is the only reason I have one in my ship and it would be the same even if GPS had never been invented. Where I fly the compass is useless.

I'm sure the F35 has a magnetic compass. Odds are it costs $250,000, was designed to do triple duty as magnetic direction indicator, disco ball and contractor cash flow enhancer and averages twelve hours maintenance for every hour in the air.

[Bruce Hoult]

I've seen a glider with the compass mounted in the upper inside part of the leg well.

[benso...@gmail.com]

Good point...most flight manuals do not stipulate WHERE the compass needs to be mounted.

Thanks F1 for the point to the SIRS Navigator. A good PZL KI-13A compass is almost impossible to locate.

[jfitch]

I wonder how many sailplanes have the required magnetic deviation card for their required compass.

[Dave Nadler]

On Thursday, October 29, 2015 at 11:21:11 AM UTC-4, jfitch wrote:
> I wonder how many sailplanes have the required magnetic deviation
> card for their required compass.

Wrong question! How many have actual values, and how many have
made up nonsense to satisfy the inspector?

See ya, Dave

[Dan Marotta]

From the LAK-17a Flight Manual:

For cloud flying the following additional equipment is required:

 - variometer;
 - magnetic compass compensated in the sailplane;
 - turn and bank indicator, non-icing;
 - transceiver;
 - parachute, automatic or manual opening type;
 - thermometer for outside air;
 - non-icing airspeed system.

 The minimum equipment must correspond with national regulations.

I've been instrument rated for about 41 years and I don't know what a non-icing turn and bank indicator is or how it works.  Could someone enlighten me, please?  And let's not forget the pitot and static heat!  Maybe total energy probe heat, as well.  There's a mag compass mounted at the far forward end of my glare shield (probably from the factory) with a nice, flat black aluminum hood over it.  It's below the level of the plexiglass and unobtrusive and I practically never look at it.  Instead, I use that mountain 100 miles distant to orient myself.

On 10/28/2015 10:12 PM, SoaringXCellence wrote:

Oops, I stand corrected, the TCDS for the Libelle requires a compass, HOWEVER, the pilot manual says that the compass is only required for cloud flying.

--
Dan, 5J

[Dan Marotta]

<Snip>

I wonder how many sailplanes have the required magnetic deviation card for their required compass.

</Snip>

Shhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh.....

--
Dan, 5J

[Jonathan St. Cloud]

I just googled searched for photos of F-22 and F-35 cockpits and instrument panels, did not see a compass. Sure there is a gryo, but could not find a non electronic compass. I too think it is a relic of days gone by. I have three gps' in my bird, a selection of three batteries with turtle deck solar panels, I can use to power the instrument cluster and each instrument is individually fused. As a back up I have an iPhone, and maps where by I can align the topographic features to what I see outside, thus determine the rough compass headings.

In 4,500 hours of flying I have only used a vertical card compass to determine the direction of the runway while approaching an airport. Now with my moving map, I think I shall not even do that.

[Dave Nadler]

On Thursday, October 29, 2015 at 1:30:07 PM UTC-4, Jonathan St. Cloud wrote:
> I have three gps' in my bird...

Shocking. Time to upgrade. Minimum equipment:

PowerFlarm
Logger#2
AHRS w/GPS
Personal tracker
406ELT w/GPS
iPhone w/GPS

Obviously you're way behind!
And probably not enough batteries either ;-)

[ifee...@hotmail.com]

A non-icing turn and bank is one that is electrically driven or powered by a vacuum pump instead of an external venturi. Walk around a small airport and you're almost certain to see older light aircraft with large external venturis used to drive the gyros. Look at enough old pictures of gliders and you'll even see them there on occasion. The drawback of using a venturi to drive blind flying instruments in the clouds should be pretty obvious.

I've got an up to date correction card in my glider. Anyone ever try flying a compass course accurate to within 2 degrees in a sailplane? Good for a laugh.

[son_of_flubber]

I used my compass to advantage this Fall (for the first time ever) when working a narrow band of rotor lift at relatively low altitude with a head wind speed that was slower than my stall speed.

I'd fly out of the rotor lift and into sink after flying straight for about 20 seconds, turn around fast and fly downwind on the opposite compass heading to roughly above my ground reference point, then fly the same upwind compass heading repeatedly. I eventually climbed a couple thousand feet into weak wave. (I really enjoy working rotor).

Moving map was turned off. Perhaps the moving map would have made it too easy, and I would have missed the 'learning experience' of working rotor without the moving map.

I'd add that the 'compass swing' was irrelevant to this exercise as the headings that I used were just arbitrary (but repeatable) numbers.

Call me 'old school' but I also feel that it is beneficial to the improvement of my 'seat of the pants' skills for me to center thermals without 'Digital Thermal Assistants'.

[jfitch]

I have 5:

Air Avionics ISU
PowerFlarm
iPhone 6+ used for iGlide
iPhone 5s used for cell phone
Delorme Inreach

Nevertheless, in the unlikely event of an EMP or the more likely event of GPS interference/unavailability, none will work.

But I have never flown a compass course in a glider. In VFR, you don't need it; in IFR, it is insufficient without an AHRS, and then you don't need it. Conclusion: you don't need it.

[George Haeh]

Canadian Regulation Gliders — Day VFR

605.21 No person shall operate a glider in
day VFR flight unless it is equipped with
(a) an altimeter;
(b) an airspeed indicator;
(c) a magnetic compass or a magnetic
direction indicator; and...

There's a few varios with that capability.

A computer with moving map that shows
magnetic bearing should also satisfy this
reg.

The chance that a Transport Canada
inspector would make a fuss over a
single seater without a compass is close
to zilch, but the guy who signs your
annual needs some coverage.

[JS]

Jon, thought I had four GPS devices but if you're counting phones, etc....
ClearNav vario
ClearNav 2
Air-Glide vario
PowerFLARM
APRS
InReach
"Phone"

Realised a week or so ago that there is no vario needle in the panel. Just triangles, lines and dots.

But there's a mysterious liquid-filled instrument near the bottom of the panel that has numbers on a wobbly thing inside.
It's not on the minimum equipment list. Should probably be stored somewhere with a sextant and knotted rope or the vacuum tube NAV radio from an Illyushin IL-76.
Jim

[Jonathan St. Cloud]

Did find a magnetic compass in the F-16. All gliders I know of do require a compass so for now I will have one. Tried to get by with a stick on compass that I bought at Auto Zone, but that did not fly (so to speak) with the examiner, so I had to install a glare shield compass.

https://www.quora.com/What-do-all-of-the-controls-in-an-F16-fighter-jets-cockpit-do

[Renny]

On Thursday, October 29, 2015 at 3:23:24 PM UTC-6, Jonathan St. Cloud wrote:
> Did find a magnetic compass in the F-16. All gliders I know of do require a compass so for now I will have one. Tried to get by with a stick on compass that I bought at Auto Zone, but that did not fly (so to speak) with the examiner, so I had to install a glare shield compass.
>
> https://www.quora.com/What-do-all-of-the-controls-in-an-F16-fighter-jets-cockpit-do

Let's see now...Hmmm....Forgetting the excellent capabilities of my LX9000, PowerFlarm, and Flarmview, does my Pathfinder watch, which really has an outstanding compass "count?" How about the compass in my Delorme inReach Explorer? It has a digital compass? Now, what year is this? Is it 1947? 1952? Geezzz...Now, please excuse me..I am trying to see if I have room in my glider for my new sextant....(available right now on the Home Shopping Network....Stock is limited, so do not delay!).... ;-)

[benso...@gmail.com]

On Thursday, October 29, 2015 at 4:15:07 PM UTC-4, George Haeh wrote:
> Canadian Regulation Gliders -- Day VFR

"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?

[Dan Marotta]

Thanks!  I'd forgotten about venturis.  I've flown a bunch of them.

On 10/29/2015 12:34 PM, ifee...@hotmail.com wrote:

A non-icing turn and bank is one that is electrically driven or powered by a vacuum pump instead of an external venturi. Walk around a small airport and you're almost certain to see older light aircraft with large external venturis used to drive the gyros. Look at enough old pictures of gliders and you'll even see them there on occasion. The drawback of using a venturi to drive blind flying instruments in the clouds should be pretty obvious.

I've got an up to date correction card in my glider. Anyone ever try flying a compass course accurate to within 2 degrees in a sailplane? Good for a laugh.

--
Dan, 5J

[Jonathan St. Cloud]

My bird has a Butterfly and Lx 90XX with compass option, but I was still require to have a manual compass.

[chip.b...@gmail.com]

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 failure: 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.

[JS]

The bastards at China Lake like to test their GPS jammers, and test them again and again. I keep this site bookmarked:

http://www.navcen.uscg.gov/pdf/gps/gpsnotices/GPS_Interference.pdf

Good thing there's always "look out the window dot com".
On one of my favorite hang glider flights both the radio and vario died before launch. Super low tech.
Jim

[jfitch]

A compass might be useful for navigation in the trackless flatlands, but out west the 12 - 13K mountains actually make better reference points even if you can't see the sun. And are pretty immune from GPS interference. Now if the Big Earthquake comes, sinking the mountains into the sea, on a cloudy day, during a GPS jamming session, maybe I'll be looking at the compass. But even then it'll be the electronic one. If the poles happen to pick that day to reverse, then we'll all be in trouble.

[jfitch]

On Thursday, October 29, 2015 at 5:32:57 PM UTC-7, chip.b...@gmail.com 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.

[Jonathan St. Cloud]

Plus the iPhone/iPad uses GPS and GLONASS. The current GPS systems always have multiple satellites locked in. Virtually all my flying is in the mountains and with the paper maps, I can visualize where I am by comparing the topo features with the map, thus getting primary headings.

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. 270 -2 + 2 is 90. The result must make sense, but I have used this method most of my flying career.

I do agree, the vertical card compass is the most useful in aviation.

[krasw]

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.

[Bruce Hoult]

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.

[Bill.D...@coloradosoaring.org]

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.

[chip.b...@gmail.com]

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). :)

[Bruce Hoult]

On Friday, October 30, 2015 at 6:26:52 PM UTC+3, chip.b...@gmail.com 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.

[Dan Marotta]

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.

--
Dan, 5J

[Dan Marotta]

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!

--
Dan, 5J

[chip.b...@gmail.com]

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.

[Mike the Strike]

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

[jfitch]

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.

[Andrzej Kobus]

I don't think there is such a thing as GPS compass, regardless if you are moving or not. GPS is measuring your position, it has nothing to do with measurement of magnetic field.

[Dave Doe]

In article <6c5cf6eb-958c-4b1a...@googlegroups.com>,
benso...@gmail.com, benso...@gmail.com says...
>
> A sailplane's Flight Manual usually requires a magnetic compass (or an
> aviation compass)as minimum equipment. Well, panel space has become
> less available and you are seeing fewer sailplanes with panel or
> glare-shield mounted 2.25 Airpath C2xxx or PAI-700 aircraft specific
> compasses.
>
> Anyone have a "point" to an off panel compass that might meet FAA
> scrunity? Unfortunately the Cook compass manufactured by COBB-SLATER
> Instruments Co. Ltd is no longer available.
> http://compassmuseum.com/aero/aero.htm#COOK
>
> Probably, a magnetic compass is the last instrument used by a
> competition pilot. Most competition sailplanes have 3 or more separate
> GPS engines and it is very simple to have them on independent battery
> sources. What would be the "penalty" if your sailplane failed a FAA
> "courtesy" ramp inspection because it lacked a magnetic compass?
>
> Does a F-35 Lighting II joint strike fighter has a magnetic compass?

I'm sure it does, but it'll be an electrical one - that is, one using a
magnetometer.

Makes me wonder, how would such a, cheap but obviously not FAA approved
device go, for gliders...

https://duckduckgo.com/?q=arduino%20magnetometer&t=lm

--
Duncan.

[marc....@gmail.com]

On Friday, October 30, 2015 at 2:20:55 PM UTC-7, Andrzej Kobus wrote:
> I don't think there is such a thing as GPS compass, regardless if you are moving or not. GPS is measuring your position, it has nothing to do with measurement of magnetic field.

You can determine orientation (including direction) by using difference in 3D position of two GPS receivers (actually their antennae) mounted at a fixed displacement from each other. It's a bit more complicated than it sounds, as ideally, the two GPS receivers will have synchronized clocks and be using the same satellites for their position solutions. So, the receivers used are quite specialized.

[Andrzej Kobus]

You are right, with two receivers and antennas far apart to mitigate the errors it is possible. Not something that one would want to mount in an aircraft.

[Bill.D...@coloradosoaring.org]

Been done. Check out Septentrio.
http://www.navtechgps.com/assets/1/7/AsteRx4_OEM_DS_V0415_41_DS.pdf

[Martin Gregorie]

You could get a reliable heading with a fluxgate (solid state) compass
but not, as you say, with a single GPS receiver.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Casey Cox]

On Wednesday, October 28, 2015 at 10:32:51 AM UTC-4, benso...@gmail.com wrote:
> A sailplane's Flight Manual usually requires a magnetic compass (or an aviation compass)as minimum equipment. Well, panel space has become less available and you are seeing fewer sailplanes with panel or glare-shield mounted 2.25 Airpath C2xxx or PAI-700 aircraft specific compasses.

Grob Astir CS does not require as minimum equipment.

https://www.dropbox.com/s/yjlrf96sbfpsyy3/Screen%20Shot%202015-10-30%20at%208.28.23%20PM.png?dl=0

[Jonathan St. Cloud]

Please correct me if I am wrong, but doesn't the Butterfly S and the LX90XX with compass option both have fluxgate compass? One would think with these instruments we would not have to have a whiskey compass, that just takes panel/glare-shield space.

[benso...@gmail.com]

On Friday, October 30, 2015 at 8:47:15 PM UTC-4, Jonathan St. Cloud wrote:
> Please correct me if I am wrong, but doesn't the Butterfly S and the LX90XX with compass option both have fluxgate compass? One would think with these instruments we would not have to have a whiskey compass, that just takes panel/glare-shield space.

Perhaps LXNAV has the best chance of approval as the new LXNAV Compass module is advertised as a magnetic compass and sold as a separate (add-on) feature. A better job of "wordsmanship" than Air Avionics' Butterfly S.

If only the sailplane manufactures would release a Technical Bulletin stating these devices satisfy intention. But in today's world of government oversight and manufacture's liability risk, a snowball in hell has a better chance.

[jfitch]

The Butterfly S doesn't have a compass option, it has the compass as a standard feature. The issue might be whether regulations require a TSO'd compass.

[jfitch]

There are two types of GPS compasses I have seen (for boats). One has three antennas arranged in a triangle about 12 inches apart and does not use their GPS position, rather they measure signal delay and knowing the position of the satellite constellation determine orientation. They are quite accurate immune to deviation and motion errors. More common recently are the two GPS receiver versions that determine orientation by position. Furuno and Vector make them and probably others with claimed RMS accuracy of 0.5 deg. Less than $2K :).

[ifee...@hotmail.com]

> Grob Astir CS does not require as minimum equipment.

It's not in the flight manual but it is in the F.A.A. type certificate G33EU under required equipment.