Compass Calibration

[Mark B]

Can anyone advise on the distance between flight locations before having to recalibrate the compass?

I have made up my own rule of anything more than 20 miles, but this is really only a 'finger in the air', and not based on anything scientific.

The process requires removal of the camera and then refitting afterwards, which is a bit of a pain in the butt, so if I could stretch out the distances then that would be a great help.

 

[BobW55]

It is not so much the compass, as it is the GPS. I have yet to take my H more than 50 miles to any location so I never really worried about it.
Most feel that if your location changes by a great distance (100 miles),
That you should let the aircraft sit powered up and let the GPS download new information and stabilize. This process could take 15 minutes. Now that may sound like a long time, but is the loss of your aircraft worth it?

 

[Mark B]

Thanks Bob.

 

[Rayray]

Over time I have learned to leave mine alone.
In a new location, watch the craft rear indicator light after takeoff, and after raising or lowering the legs. Yellow flashes are compass errors. A couple of quick flashes are OK, but continual yellow flashes or ST16 warnings indicate a need for recal.
And I agree with Bob.

 

[PatR]

There's no hard rule on distance between locations but Bob's suggestion is a good one. Mine have seen many 20-50 mile trips and performed fine without a new cal. On every trip over 500 miles they have performed better after a calibration.

 

[ThunderChicken]

I might be overly cautious, if mine has been off for an extended period of time(More than 2 days) or I travel more than 10 miles I calibrate before flight.

 

[Racepro60]

Do all cameras need to be removed to do compass cals?

 

[Photo]

I might be overly cautious, if mine has been off for an extended period of time(More than 2 days) or I travel more than 10 miles I calibrate before flight.

When you go east-west or west-east more than 100miles / 160km it's important to recal.your compass. If you haven't been in the air for a 4-7 days or so you have to wait at least 14 minutes for sats lock! Important!

 

[kd4pbs]

Do all cameras need to be removed to do compass cals?

From my investigation into this, it's a good idea to keep it on the aircraft. It does affect the compass reading.

 

[Racepro60]

From my investigation into this, it's a good idea to keep it on the aircraft. It does affect the compass reading.

That's what I thought, I had not read where you should remove camera to cal the compass, but I'm a newby, So thanks !

 

[Rubik]

We're talking about 3 things here:

First, as Photo said, the compass needs to be recalibrated if you've traveled 50-100 miles east/west since the relative position of north changes significantly.

Second, the GPS needs time to reload the almanac if you haven't flown in a couple of weeks or if you have traveled to a new location 20-50 miles (est.) from your last flight. Just because it sees plenty of satellites, doesn't mean it is ready to go. You can launch the TH and watch for drift with no control input. If it drifts, come back down and wait the remainder of the 12 minutes.

Third, I've done the compass calibration both ways, with camera on and off. It didn't seem to make any difference, except it is a bit disturbing to see the gimbal flopping around with camera on.

 

[PatR]

Been working with gimbaled cameras for the past decade or so. With every one, they are secured to prevent the kind of abuse the CGO gimbal is subjected to when not in active use. If you value your gimbal more than you are concerned about a couple degrees of compass accuracy, remove it when you do a compass cal. They run ~$550.00 to replace. The actuators are small and fragile, and the system has stop limits programmed into the gimbal. The spinning of the cal process wildly exceeds the stop limits and imposes forces on the actuators they are not designed to handle.

After a year and a half and a great many flights on two H's I have yet to experience a condition where removing the gimbal for a compass cal generated any negative effect on flight performance whatsoever, GPS on or off. I also have never had problems with my gimbals or gimbal controls.

It's your H, so what you think is right.

 

[gwhuntoon]

The FAA provides a good resource describing magnetic variation. Click on the link below then go to page 7 under magnetic variation. Fig. 16-9 is a good map showing +/- degrees of variation so you can begin to judge how far you're traveling against the diagram. The starting point for agonic lines is arbitrary, I just happen to be under 0°. The further you travel from 0° east / west and south the greater the distance you can travel before you may want to re-calibrate your compass. If you live near 0° or in the northern US the lest distance you can travel. (Assuming you live in the US)

https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/18_phak_ch16.pdf

 

[Racepro60]

Been working with gimbaled cameras for the past decade or so. With every one, they are secured to prevent the kind of abuse the CGO gimbal is subjected to when not in active use. If you value your gimbal more than you are concerned about a couple degrees of compass accuracy, remove it when you do a compass cal. They run ~$550.00 to replace. The actuators are small and fragile, and the system has stop limits programmed into the gimbal. The spinning of the cal process wildly exceeds the stop limits and imposes forces on the actuators they are not designed to handle.

After a year and a half and a great many flights on two H's I have yet to experience a condition where removing the gimbal for a compass cal generated any negative effect on flight performance whatsoever, GPS on or off. I also have never had problems with my gimbals or gimbal controls.

It's your H, so what you think is right.

Thanks for saving me from myself, like I said I'm a newby so any help from veteran pilot/photographers is much appreciated

Thanks !

 

[Rubik]

The FAA provides a good resource describing magnetic variation. Click on the link below then go to page 7 under magnetic variation. Fig. 16-9 is a good map showing +/- degrees of variation so you can begin to judge how far you're traveling against the diagram. The starting point for agonic lines is arbitrary, I just happen to be under 0°. The further you travel from 0° east / west and south the greater the distance you can travel before you may want to re-calibrate your compass. If you live near 0° or in the northern US the lest distance you can travel. (Assuming you live in the US)

https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/18_phak_ch16.pdf

Excellent reference! Thanks for posting. Here's an important quote from that reference:

"If the Earth were uniformly magnetized, the compass needle would point toward the magnetic pole....Actually, the Earth is not uniformly magnetized. In the United States, the needle usually points in the general direction of the magnetic pole, but it may vary in certain geographical localities by many degrees."​

Hence, Figure 16.9.

So, for someone in the Pacific Northwest, I should recalibrate the compass when I move to locations to the SE or NW. How far is still a matter for debate.

 

[PatR]

The FAA publishes a tremendous number if free informational resources on the website. We just have to dig them out

 

[themiddleman07]

I've never once calibrated the compass on my H (owned for 3 months). Took it out of the box, charged it, and flew right away as soon as I got the green "ready" on my controller. Many successful flights and never had to calibrate. Even landed it on a 3 foot wide hiking trail on the side of a very steep mountain trail above a lake and it has performed beautifully. What should I be looking for as a sign it needs to be calibrated?

 

[FlushVision]

...<snip>... What should I be looking for as a sign it needs to be calibrated?

1.
When the system tells you to...a warning to re calibrate on the ST16

2.
Whenever you see any unusual behavior of your aircraft...for example, veering to the right or left when the aircraft should be going ahead in a straight line (note that this behavior can also be caused by calibration issues in the ST16 as well).

In my opinion the compass should be calibrated at least occasionally. I do it after traveling a distance from the last place it was calibrated, but if you aren't seeing any issues with your fights and you aren't seeing any warnings on your ST16 or on your aircraft's led, then who am I to judge? There is an argument that calibrating too often can let in a bad calibration with obvious consequences.

 

[glider]

After the initial calibration and library loadout of the GPS unit,

When you go east-west or west-east more than 100miles / 160km it's important to recal.your compass. If you haven't been in the air for a 4-7 days or so you have to wait at least 14 minutes for sats lock! Important!

I see no reason for this (bold). If GPS locks and hdop is good, I go.

 

[kd4pbs]

I've found that I would sometimes get "compass needs calibration" errors when I'd calibrate without the camera on the aircraft, but then installed the camera to fly. That's what led to the experiment I posted to see how far out it would skew the compass (quite a bit), and the revelation that it was a good idea to calibrate with the camera on the aircraft.
Perhaps other Typhoon H's don't have as much of an issue due to manufacturing tolerances?
Until Yuneec comes out with a statement to the contrary, I'll continue to calibrate it the way they tell us. No need giving them any more fodder in case of a crash relating to compass errors.