Glider installation

[fredjoy]

I am considering installing a Dynon 10A in a new build self launching single seat motor glider in lieu of a electric gyro horizon. Cockpit space and panel space in gliders is very limited although hopefully it will be possible to fit it in the panel but close to backup gyro turn and slip, electronic engine management instrumentation, gliding computer, mode S transponder, RT set and magnetic compass. Reading through the manual and these forums I think it will be essential to fit a remote compass module. Choosing a location for the remote compass module is very difficult. No room in the cockpit other than behind the pilot headrest and this location will be close to a 12v battery. The pop up engine is also immediately behind the the cockpit. Other possibilities are somewhere in the wing or preferably mid fuselage. The whole aircraft is carbon composite construction and if the compass module is to be mounted in either the wing or fuselage this will have to be done as the glider is constructed. Once installed the module will be inaccessible.
1) I would be interested to hear from anyone who has installed a Dynon 10A in a composite glider or motorglider, where you installed the compass module and the overall success or otherwise of the installation.
2) Is the composite carbon fibre construction likely to cause problems regarding the sensitivity or accuracy of the compass module.
3) How close to the transponder ground plane and aerial can the compass module be fitted.

Any advice, experience or comments would be appreciated.

 

[Etienne]

Why do you need the remote module? Unless you have serious current flowing around the D10A, or lots of steel work (and I mean lots, and close to the D10) then the internal compass will probably do the job.

The electronic compasses of today (and in particular the EDC-10) has the ability to compensate for a large amount of constant disturbance in the Earth's magnetic field by constant current carrying wires and ferrous metal framework. Obviously if you put the sensor into a steel box, you probably won't be able to detect any field, so that won't work, but as long as the sensor's environment doesn't change the calibration done should be enough to correct the constant anomalies.

If your aircraft is mostly carbon fibre, then the disturbance to the sensor should be minimal. I fly a rag and tube aircraft and have the sensor mounted on one of the king posts (lots of 4130 steel in every direction), and have about a 1-2 degree accuracy through all 360 deg.

Aluminium aircraft generally don't have too much in the way of ferrous metals around, so the disturbances are minimal...

 

[fredjoy]

Thank you Etienne for you prompt response and I find you comments regarding the compass very encouraging. If I can avoid the need to fit a remote module it will simplify the installation considerably. As I said before the panel space in gliders is extremely limited and the instruments have to be stacked and butted together in a panel at its widest 270 mm and a depth behind the panel face of 200mm. A lot of instrument bodies, wires and tubing in a very small volume. Running power requirements if all instruments are on, on the 12V system will be just under 30 watts. Hence my belief that a remote compass module would be required.
The close packing of the instruments and the power requirement of the Dynon 10A does raise another issues regarding installation in a glider. I have been told that when operating the Dynon heats up considerably and in a close packed panel with restricted air circulation this could be a problem. Of course in a GA aircraft this problem will not arise or if it does better ventilation can more easily be fixed.
Used for the main purpose in a glider as a horizon I think that the Dynon 10A has many advantages over an electric gyro horizon. As far as I am aware very few have been fitted in gliders and as a possible early adopter I have a steep learning curve to undertake.
Looking forward to other comments, suggestions and experience which will help me make up my mind.

 

[Etienne]

Just bear in mind that if you're going to need to put a normal compass anywhere near the D10, you're going to have big issues, as the normal compass has it's own very strong (compared to the Earth's) magnetic field...

If you're careful about the routing of the wires, and don't use a common ground electrical system, it should be fine. In other words, if the power delivery to each instrument is made using a twisted pair of positive and ground, so that the resulting magnetic field is contained within the power cable, and the power cable isn't wrapped around the body of the D10 : , then it shouldn't affect the electronic compass much at all. Also, if the current draw along these power lines is constant, and the power lines are secured so that they don't move at all, then the calibration should be able to handle it. However, if you have an instrument that has a very large power requirement fluctuation, like a radio or a transponder, then you may need to route the power cables away from the D10.

A radio or transponder may interfere with the compass for a different reason - the RF coming from the aerial affects the magnetic field in it's immediate vicinity. If the aerial is too close to the D10, it will cause havoc with the compass whilst transmitting.

I'd wait for the official Dynon response before ordering one though This is just my opinion as an electrical engineer...

 

[dynonsupport]

Given the density of the instruments in your panel, we're skeptical that you'll be able to get a great heading measurement without the remote magnetometer.

As the EFIS-D10A is an electronic device, it does produce heat, but not an inordinate amount. If you left one one perpetually on a table at ambient temperatures (like we do at airshows), they'll be warm to the touch, but never too hot to touch. If you coop that heat up in a really dense panel that prevents that heat from being dissipated, you can of course experience some heat buildup. If the unit gets itself to 50C, it will warn with a temperature out of spec message. We've historically only seen this in only really tight panels with no ventilation, or occasionally an airplane that's been sun-baked in the desert.

 

[fredjoy]

Thanks again Etienne this is all very useful information for me. The positioning of the magnetic compass is clearly an issue here. There is no room for it in the panel and it will have to be mounted in the normal position for gliders. Usually a pedestal type compass is mounted on top of and at the back of the instrument pod. In this position the magnetic compass will be within four inches of the rear body of the Dynon 10A which can only be fitted on the top instrument row. In the UK and soon to be under EASA a magnetic compass together with the ASI and altimeter is considered to be a minimum primary instrument and will require to have EASA release note. The Dynon 10A would be a secondary instrument and its compass display would not be an approved magnetic compass. To accommodate the magnetic compass it looks like I am back to needing a remote compass module. In the UK all this European legislation is giving us nothing but hassle. Years ago we would have been much better off twinning with the USA than voting to go into the European Common Market. Too late now.