Van's Air Force
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Magnetometer Mount
- Thread starter gvgoff99
- Start date
Sam Buchanan
been here awhile
The mag for my Dynon (and even earlier the mag for a BMA alpha test unit) has resided on that deck on my RV-6 for several years. There are no issues with ferrous interference. I suggest the mag be mounted on a bracket that will allow you to incline the device a few degrees to match the inclination of the EFIS for enhanced accuracy. I packaged the magnetometer in a plastic bag prior to final mounting to prevent water from running down the vertical stab onto the mag. The mag is attached to my bracket with zip-lock ties.
n5lp
fugio ergo sum
Mine, for a Dynon, does well there also. I used a bracket to get the angles in alignment but I think I used non-ferrous screws rather than zip-locks, for mounting but I did the plastic bag thing also.
Would using nylon washers and screws work also for attaching and adjusting?
Ron Burnett
RV-6A finishing
Sam Buchanan
been here awhile
Sure, any non-ferrous attachment will be fine.
You could probably do it with velcro.
beechrv9a
Well Known Member
What does the back deck mounting bracket look like?
I have not ordered the magnometer yet, but am at the point of figuring out where to mount it before installing the top skin (on the back deck or btwn the 706 and 707 bulkheads . Do you have a picture of your mounting bracket for the back deck? Is it easy to access if ever needed back there?
I have not ordered the magnometer yet, but am at the point of figuring out where to mount it before installing the top skin (on the back deck or btwn the 706 and 707 bulkheads . Do you have a picture of your mounting bracket for the back deck? Is it easy to access if ever needed back there?
Sam Buchanan
been here awhile
Jim, maybe I wasn't clear enough with my description. The deck is the "shelf" under the leading edge of the vertical stab that is exposed when you remove the emp fairing. This makes the mag very assessable without having to crawl back into the tailcone. Also is convenient for locating the OAT probe under the horiz stab since the probe connects to the mag.
I don't have a photo, the bracket is just something I whipped up out of scrap stock in a few minutes using the TLAR school of engineering (That Looks About Right).
beechrv9a
Well Known Member
I see
Thanks, I thought maybe I was missing something.
Jim, maybe I wasn't clear enough with my description. The deck is the "shelf" under the leading edge of the vertical stab that is exposed when you remove the emp fairing. This makes the mag very assessable without having to crawl back into the tailcone. Also is convenient for locating the OAT probe under the horiz stab since the probe connects to the mag.
I don't have a photo, the bracket is just something I whipped up out of scrap stock in a few minutes using the TLAR school of engineering (That Looks About Right).
Thanks, I thought maybe I was missing something.
rv9av8tr
Well Known Member
GRT Sport Magnetometer mounting
This is how I mounted my GRT magnetometers. The angle bracket allowed me to set the angles to match the pitch and roll of the EFIS AHRS, as mounted in the instrument panel. (The Sport AHRS is integral to the EFIS).
http://www.mykitlog.com/users/display_log.php?user=n539rv&project=161&category=3987&log=72925&row=10
This is how I mounted my GRT magnetometers. The angle bracket allowed me to set the angles to match the pitch and roll of the EFIS AHRS, as mounted in the instrument panel. (The Sport AHRS is integral to the EFIS).
http://www.mykitlog.com/users/display_log.php?user=n539rv&project=161&category=3987&log=72925&row=10
OneCharlieKilo
Well Known Member
Dynon digital compass module on front side of back deck
I put mine on the front side of the aft bulkhead where I could still reach it without getting in the tail cone but felt like it was a little better protected from water leaking by the fairing onto the horizontal deck (although clearly not completely "weather-proof"). It's mounted to match the correct angle and is screw mounted into nutplates on the rails so angle can be adjusted by adding/removing washers.
view from rear (the artwork on the rear bulkhead was my youngest daughter's contribution when she wanted to help me out in the garage):
view from inside the tailcone (same comment on the artwork...the drawings are upside down because she was "working" on the fuselage while it was upside down in the jig when she was about 6 yrs old):
There are a couple other pictures and description of the EDC install on my project web site at:
http://rv6aproject.ckhand.com/panelAndElectrical/panel/panelPg5.htm
I put mine on the front side of the aft bulkhead where I could still reach it without getting in the tail cone but felt like it was a little better protected from water leaking by the fairing onto the horizontal deck (although clearly not completely "weather-proof"). It's mounted to match the correct angle and is screw mounted into nutplates on the rails so angle can be adjusted by adding/removing washers.
view from rear (the artwork on the rear bulkhead was my youngest daughter's contribution when she wanted to help me out in the garage):
view from inside the tailcone (same comment on the artwork...the drawings are upside down because she was "working" on the fuselage while it was upside down in the jig when she was about 6 yrs old):
There are a couple other pictures and description of the EDC install on my project web site at:
http://rv6aproject.ckhand.com/panelAndElectrical/panel/panelPg5.htm
Norman CYYJ
Well Known Member
I might be wrong but it appears that you have your unit mounted out by 180 degrees. I think that the cable should be coming out of the unit aft and not forward.
[The photos show the correct orientation. S. Buchanan]
[The photos show the correct orientation. S. Buchanan]
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OneCharlieKilo
Well Known Member
Yes, the installation in the pictures above is correct with the connector towards the front and the tabs down. Orientation is shown on page 3-1 of D-100 installation manual.
And once you perform the calibration process, including entering the magnetic inclination and intensity per the Dynon instructions, it works great...much better than any wet compass I've flown with.
And once you perform the calibration process, including entering the magnetic inclination and intensity per the Dynon instructions, it works great...much better than any wet compass I've flown with.
dhall_polo
Well Known Member
another option on where to put the magnetometer
In the pic below, you're looking at a tray mounted just aft of the rear baggage bulkhead. The tray is a little beefy because of that chunky Crossbow AHRS on the left. The magnetometer on the right is very light and wouldn't require much for support.
Obviously, from the other posts, the rear deck works, but in my case, this did not meet the conditions spelled out for my magnetometer or the ahrs. There are high-tension strobe lines running out to the rudder, and the rudder cables are also moving ferrous material. Both were to be avoided by more than 24". The top of this baggage bulkhead is more than 24 inches from strobe, pitch servo, and rudder lines. It is close to the seatbelt lines, but those are also immobile, so the alignment program will adjust for these.
This area is also reasonably accessible in a finished airplane. (Of course reasonably accessible has new meaning in an airplane.)
In the pic below, you're looking at a tray mounted just aft of the rear baggage bulkhead. The tray is a little beefy because of that chunky Crossbow AHRS on the left. The magnetometer on the right is very light and wouldn't require much for support.
Obviously, from the other posts, the rear deck works, but in my case, this did not meet the conditions spelled out for my magnetometer or the ahrs. There are high-tension strobe lines running out to the rudder, and the rudder cables are also moving ferrous material. Both were to be avoided by more than 24". The top of this baggage bulkhead is more than 24 inches from strobe, pitch servo, and rudder lines. It is close to the seatbelt lines, but those are also immobile, so the alignment program will adjust for these.
This area is also reasonably accessible in a finished airplane. (Of course reasonably accessible has new meaning in an airplane.)
I'm trying to figure out where to put my magnetometer right now. I like where you mounted yours but I have a slider canopy. Do you think the rear bow of the slider being about 6" away would be a problem for that location. Of course it may be moving back an forth and even closer to it until takeoff.
Noah
Well Known Member
Compass unaffected by shielded strobe wires >1" away
I decided to run a test to see whether a sensitive compass would be affected by proximity to the nav/strobe which is going in my rudder, since I am proposing to install the magnetometer on the Horiz Stab deck and run the cable along the belly, which is 15" away, not the 24" that AFS recommends. I was also concerned about the moving ferrous rudder cables which are also significantly less than 24"
First, I connected a long length (50') of shielded, three conductor 22AWG cable supplied with the strobe kit from CreativAir between the CreativAir (now Whiskey Victor) strobe power supply (AviPak 60W, 4 outlet) and my Whelen strobe / nav light combo (P/N A500A-V-14).
I used a Silva Ranger compass that I have been backpacking with for 20 years that I am very confident in. Basically, the needle would vacillate about 1 degree if the wire was RIGHT ON TOP OF the compass with the strobe pulsing at high power and 4 rapid-pulse flashes (Max power). Any separation greater than 1 inch would result in NO MOVEMENT of the compass needle. I also tried the nav light only, turning it on and off, and got NO MOVEMENT of the compass needle, even with the wire right on top of the compass. At 15", obviously there was also no movement. However, the needle would vacillate about 2 degrees if it was within 2 feet of the strobe's power supply. So I'd definitely be more concerned about being close to that than being close to a shielded strobe cable.
Movement of the stainless rudder cables had absolutely no effect on the compass needle.
As a result of this test, I feel pretty confident that strobe cable EMI (electromagnetic interference) will not be a problem that will affect the magnetometer in my proposed location. Nor the rudder cables. Thus my magnetometer is going on the HS deck. No extra bracket to fab, and no extra weight
I decided to run a test to see whether a sensitive compass would be affected by proximity to the nav/strobe which is going in my rudder, since I am proposing to install the magnetometer on the Horiz Stab deck and run the cable along the belly, which is 15" away, not the 24" that AFS recommends. I was also concerned about the moving ferrous rudder cables which are also significantly less than 24"
First, I connected a long length (50') of shielded, three conductor 22AWG cable supplied with the strobe kit from CreativAir between the CreativAir (now Whiskey Victor) strobe power supply (AviPak 60W, 4 outlet) and my Whelen strobe / nav light combo (P/N A500A-V-14).
I used a Silva Ranger compass that I have been backpacking with for 20 years that I am very confident in. Basically, the needle would vacillate about 1 degree if the wire was RIGHT ON TOP OF the compass with the strobe pulsing at high power and 4 rapid-pulse flashes (Max power). Any separation greater than 1 inch would result in NO MOVEMENT of the compass needle. I also tried the nav light only, turning it on and off, and got NO MOVEMENT of the compass needle, even with the wire right on top of the compass. At 15", obviously there was also no movement. However, the needle would vacillate about 2 degrees if it was within 2 feet of the strobe's power supply. So I'd definitely be more concerned about being close to that than being close to a shielded strobe cable.
Movement of the stainless rudder cables had absolutely no effect on the compass needle.
As a result of this test, I feel pretty confident that strobe cable EMI (electromagnetic interference) will not be a problem that will affect the magnetometer in my proposed location. Nor the rudder cables. Thus my magnetometer is going on the HS deck. No extra bracket to fab, and no extra weight
Sam Buchanan
been here awhile
Movement of the stainless rudder cables had absolutely no effect on the compass needle.
As a result of this test, I feel pretty confident that strobe cable EMI (electromagnetic interference) will not be a problem that will affect the magnetometer in my proposed location. Nor the rudder cables. Thus my magnetometer is going on the HS deck. No extra bracket to fab, and no extra weight
I came to the same conclusion, and the RV-6 also has that big chunk of steel, the tailwheel spring.
You will probably want a simple bracket that will incline the mag the same amount as the instrument panel (Smart Level really comes in handy for this) which will most likely give you a smoother calibration routine.
Magnometer mount problem
I decided to mount the magnometer for the AFS EFIS behind the baggage area on the vertical support about half way up. This put me over a foot from any metal cable or canopy rear bow. After spending a lot of time on a bracket, I got it mounted and checked it out. Unfortunately when I slide the canopy back I get about a 4-5 degree turn on the EFIS. It is very repeatable when going open or closed. I checked this location out with a compass before hand and didn't see any issues. The magnometer must be more sensitive. The slider canopy frame will place metal on three sides of the magnometer within a foot as you slide it back. Now I've moved it near the back deck, just inside the fuse similar to a previous post. Unfortunately the AFS wiring harness that Stein makes doesn't come with cable long enough to reach that far so I'll be ordering more cable. So if you have a slider canopy I wouldn't suggest mounting it behind the baggage area based on my findings.
I decided to mount the magnometer for the AFS EFIS behind the baggage area on the vertical support about half way up. This put me over a foot from any metal cable or canopy rear bow. After spending a lot of time on a bracket, I got it mounted and checked it out. Unfortunately when I slide the canopy back I get about a 4-5 degree turn on the EFIS. It is very repeatable when going open or closed. I checked this location out with a compass before hand and didn't see any issues. The magnometer must be more sensitive. The slider canopy frame will place metal on three sides of the magnometer within a foot as you slide it back. Now I've moved it near the back deck, just inside the fuse similar to a previous post. Unfortunately the AFS wiring harness that Stein makes doesn't come with cable long enough to reach that far so I'll be ordering more cable. So if you have a slider canopy I wouldn't suggest mounting it behind the baggage area based on my findings.
Discovering that your magnetometer location is less than ideal after you have already built a mount, run the wires, and closed things out is a real pain! That's one reason I like to wire and power up systems as I build - build a little, test a little. In the case of the EFIS, I just strung the magnetometer cable out full length, and tested it in various locations as I moved the controls, slid the canopy around, etc.
In my case I found the ideal spot about half-way back to the tail of the RV-8, on a bulkhead mount. I would not be surprised to find that the location varies from aircraft to aircraft, as different steel parts might very well have some magnetic variations. Which means that before you rely on someone else's location - test, test, test!
Paul
In my case I found the ideal spot about half-way back to the tail of the RV-8, on a bulkhead mount. I would not be surprised to find that the location varies from aircraft to aircraft, as different steel parts might very well have some magnetic variations. Which means that before you rely on someone else's location - test, test, test!
Paul
Sam Buchanan
been here awhile
Why is this a problem....unless you fly with the canopy open?
Just make sure your canopy is closed when you run the calibration routine and you should be good to go.
Why is this a problem....unless you fly with the canopy open?
Just make sure your canopy is closed when you run the calibration routine and you should be good to go.
You're correct, I won't be flying with the canopy open. Although normally I might adjust the DG on my old Cessna on the parallel taxiway so I don't have to do it while sitting on the runway or on the roll. If it's a hot day and the canopy is rolled back and then I close it just before takeoff I would now be out of calibration. It's a lot of key presses on the AFS to reset it so I'd prefer not dealing with that.
There was a topic on the AFS forum about the bolts connecting the horizontal stab causing issues when mounting on the back deck. So how do you test for that short of removing the bolts and putting them back in? I now understand why the instructions indicate 2 feet from anything metal. It's unfortunate that it's almost impossible to do.
Sam Buchanan
been here awhile
Not sure if I correctly followed your train of thought in your first paragraph (you have a DG??). If you are thinking that you will have to recalibrate your mag every time you open and close the canopy, this is not the case. If the magnetometer is properly calibrated with the canopy closed, then you will only see a heading error when the canopy is open. Once the canopy is closed, the mag will be back in its calibrated environment and will be accurate.
Ferrous objects that don't move are generally not a problem with mag accuracy since the calibration routine will allow for those masses. In my RV-6, the mag is only a foot away from the tailwheel spring which is a huge chunk of steel. But since the spring doesn't move, the Dynon routine handled the spring and mag accuracy is very high. I've had four mags (two different vendors) in that location and they all worked fine. Little stuff like bolts have not been a problem for my magnetometers.
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N941WR
Legacy Member
Why put a DG in? The Dynon is very reliable. If I did anything, I would put a whiskey compass in as a backup; simple, light, and I've known gravity not to work. Or in my case, my Garmin 496 is my backup since it can be run independent of all the aircraft systems.
BTW, I also mounted mine off the 707 bulkhead.
Why put a DG in? The Dynon is very reliable. If I did anything, I would put a whiskey compass in as a backup; simple, light, and I've known gravity not to work. Or in my case, my Garmin 496 is my backup since it can be run independent of all the aircraft systems.
BTW, I also mounted mine off the 707 bulkhead.
No, I'm not installing a DG in the RV. I currently have a vacuum DG in my Cessna (which the RV will replace some day soon) and my routine is to adjust it while on the parallel taxiway to the runway heading. So that routine won't work in the RV if the slider is open during taxi. So I'll just move the magnometer so the canopy frame doesn't affect it. Thanks for the input.
N941WR
Legacy Member
No need to move it as long as you calibrate the magnometer with the canopy closed. Who cares if it is off a little when it is open?
Sam Buchanan
been here awhile
Mark,
You are going to love your magnetometer.
Your calibrated mag/heading indicator does not require "setting" before each flight, never processes, and doesn't have turning errors......welcome to the 21st century!
Once you have carefully calibrated your magnetometer with the canopy closed, as long as major mods/repairs are not made to your avionics, no further adjustments or settings are required....ever. Accuracy within +-one degree or so should be easily attainable. Matter of fact, your magnetometer should have better resolution than the compass rose at the airport.
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Capflyer
Well Known Member
In Wingtip
I mounted mine in the wing tip. Wanting to be sure there would be no interference issues from the start so made a simple block of foam sandwiched between a couple layers of fiberglass cloth about 1" thick. Glued it into the bottom of the wing tip then used nylon screws to hold the magnetometer onto the block. Very quick and simple....and it works great. No worries about interference with anything out there.
I mounted mine in the wing tip. Wanting to be sure there would be no interference issues from the start so made a simple block of foam sandwiched between a couple layers of fiberglass cloth about 1" thick. Glued it into the bottom of the wing tip then used nylon screws to hold the magnetometer onto the block. Very quick and simple....and it works great. No worries about interference with anything out there.
tonyjohnson
Well Known Member
8
Does this position work with an RV8A? My rear deck looks a bit different that those in the pic.
Does this position work with an RV8A? My rear deck looks a bit different that those in the pic.
