Compass

[Dafydd Llewellyn]

The best direct-reading magnetic compass I have come across is the LUN compass fitted to Blaniks. It's a 3 1/8 inch instrument, and designed for a vertical panel, and it was good enough to do procedure turns on. The ones fitted to Australian Blaniks are southern-hemisphere dip compensated. They get had to read as they get old.

 

 

[Eric McCandless]

In response to Erics reply. With heading to top presentation on say a garmin, doesn't it show where you are pointed.? I disposed of my 296 a while ago.. I realise you have to be moving as a GPS is not a compass.

A GPS receiver does not know the direction the aircraft is pointing (heading) even when moving unless it has an inbuilt compass, but that is the function of the compass not the GPS itself. There is no way for a single GPS to determine the direction the receiver is pointing. It can determine which direction the receiver is moving (track), but that is not necessarily the heading depending on wind. It might be possible for some exotic system of multiple GPS receivers separated by some distance to do it but this would be outside the realms of consumers/prosumers and not practical in our aircraft. The 296 does not have an in-built compass but does have an E6B calculator to compute winds aloft if you manually input a compass/gyro heading, but not the other way around. Eric

 

 

[Graham Pukallus]

Being a trike,my first suggestion would be a VSI for thermaling, or a watch / clock, see photo for use with navigating.

 

 

 

[skeptic36]

Hi Graham and all,

 

Thanks for the suggestions/comments. Given that there doesn't seem to be anything of much use that would still work in the event of electrical failure, I have decided to fit a G meter, just for kicks.

 

Regards Bill

 

 

[alf jessup]

Thanks Nev,The below pic is the panel of my new trike, on the left, an iPad mini slots in and in the centre is a mgl extreme mini efis, both of these will have a compass. Problem is on the right there is an blank space for an instrument, any ideas what to put in there would be appreciated given a compass is out of the question.

http://i951.photobucket.com/albums/ad356/Skeptic36/4a629c5ebe0708a5cded6b6086aef163_zps955e473d.jpg

Bill,

 

You could always put a photo of some cattle in that vacant spot to remind you to go home and milk them

 

Alf

 

 

[skeptic36]

Bill,You could always put a photo of some cattle in that vacant spot to remind you to go home and milk them

 

Alf

Alf mate,

The idea of going flying is to put several thousand feet between myself and my worries, I'm not bringing them with me.

 

 

[dutchroll]

Just my experience.I have one ( card compass) mounted on the dash, most objects temporarily stored anywhere nearby swings the needle, be it sunnies, pens, phone etc.

However, as you rightly suggest, the adjustment screws are for swinging at installation.

 

So if say you leave your mini iPad home one day, the compass error could be significant.

 

Phil.

I have the Precision vertical compass mounted on my front panel. We couldn't swing it, even using the maximum possible adjustments on the compensating screws underneath. Fine with the canopy open, but close the canopy and the bow causes it to diverge significantly and you simply can't get enough adjustment to have it within tolerance on all directions. It's really only for the legal requirement (being a day VFR aircraft), but one day when I get motivated I might try to change it out for an Airpath or something else.

 

 

[Dafydd Llewellyn]

You'll likely find the Airpath or whatever just as badly affected. The problem is the magnetic properties of the canopy bow, not the compass - it's just doing its job. What's the aircraft? I assume it has a 4130 steel canopy bow; excellent for strength, but 4130 is notorious for becoming magnetised. This problem is common in welded-steel tube fuselages. The logical answer, one might imagine, would be to install a remote flux-gate compass, but CAO 20.18 Appendix 1 requires a direct-reading compass as well.

 

There are methods for de-magnetizing such a component - but unless you remove whatever the cause of its becoming magnetized in the first place, it will simply keep doing it. You either have to re-locate the compass or use a non-magnetic material for the canopy bow.

 

 

[facthunter]

You might be able to run a GROWLER around it. IF you leave a piece of suitable ferrous material aligned with the earths magnetic field it will acquire magnetism if you do things like riveting or vibrate it against something. Riveting ships makes them very magnetised sometimes. Nev

 

 

[dutchroll]

You'll likely find the Airpath or whatever just as badly affected. The problem is the magnetic properties of the canopy bow, not the compass - it's just doing its job. What's the aircraft? I assume it has a 4130 steel canopy bow; excellent for strength, but 4130 is notorious for becoming magnetised. This problem is common in welded-steel tube fuselages. The logical answer, one might imagine, would be to install a remote flux-gate compass, but CAO 20.18 Appendix 1 requires a direct-reading compass as well. There are methods for de-magnetizing such a component - but unless you remove whatever the cause of its becoming magnetized in the first place, it will simply keep doing it. You either have to re-locate the compass or use a non-magnetic material for the canopy bow.

Pitts. Yeah the whole tubular structure is 4130. Making it out of something else isn't an option due to structural integrity requirements.

We may look at trying to demagnetise it at the annual. I think I'm the only one of this model Pitts (not many of this variant around) with a vertical card compass in the front. Most others have a more conventional one & haven't heard of any so bad that it can't be swung within the adjustment limits.

 

Rear is not an option. All panel real estate sold out.

 

 

[eightyknots]

cant see why you cant use one of these, might need a angled mount to keep it vertical, not exactly sure on its tolerances to angled mounting though

Do you have one of these in your Savannah, UL?

 

 

[spacesailor]

Magnetic compasses can be "Swung" using small bits of Iron around the compass body, After closeing the canopy, as per shipping.

 

spacesailor

 

 

[Ultralights]

Do you have one of these in your Savannah, UL?

Yep. mounted top the panel in the centre.