Can’t put this off anymore, have to make some decisions (the only things left more or less 
).Actually I had everything sorted out, but then came this Garmin G5 which kind of changed things all of a sudden, and I had to take out XPanel again. I thought I could “air” it here and see what you think.
I’m building a Onex. A single seat, aerobatic, tiny little airplane.
Mission: VFR, fun flying, some basic aerobatics, burger runs (or “waffle runs” around here), and an occasional longer trip.
Constraints: Very little panel space, less than a Cub (no space for G3x for instance). Already have the MGL RDAC for engine monitoring, so I “have” to use MGL EMS/EFIS (through CAN bus). Have to have transponder and radio, and will use SD on phone/phablet (Nexus 5x is included in all the alternatives)
Price wise the difference is så small it is uninteresting, it’s more the functionality/necessity I’m wondering about.
The original plan is to use MGL iEFIS lite:
Pros: fully configurable (can make a separate page for aerobatic for instance in addition to pages for navigation), easy to install (gyros, GPS etc included inside)
Then came the G5, which really looks to be an extremely nice device, 100% self contained with battery backup. But it’s small, so I would need additional instruments for everyday use. The MGL xtreme EMS is used here-
Pros: True redundancy, also with fully digital setup. This will make it more robust regarding a single failure. I would believe Garmin will sell tons of G5s, so they are likely to be upgraded and become better and better very fast.
But, I could shoehorn an analogue ASI and alt with my original setup, which will create the same level of redundancy
Pros: True redundancy, very much like my original plan.
But then I could also use the MGL Xtreme EFIS. This has the “correct” size for everyday use, and work very much like the G5 in all other respects, except it needs an additional box for the gyros and has no battery backup (it has a GPS on board). This can be with or without analogue backup-
For all configurations I have, in addition to the normal indications (speed etc), GPS,.HSI and gyros (AI), so the functionality is the same. It is really only regarding redundancy and how good they are to look at that differentiate them. For aerobatics the main thing is speed, RPM and G (alt, VSI secondary). With redundancy, my thoughts are that it’s more of a “nice feeling” than a factual necessity due to the GPS on the phablet. But then again, to have real numbers for ASI and alt is much better than some GPS derived approximations, that in a windy situation may be very wrong
The iEFIS has lots of added functionality (VR and so on), but will I ever bother to use such things? The G5 alternative has all the functionality I need, but it also has much more redundancy than I feel I need (for everyday use it will only function as an AI).
You seem to be very limited on real estate, indeed. So much that, for any kind of travelling, glass might well be the ony option. At least, it will be the most cost-effective, for a new build. And as you have been shown, I have zero experience with glass panels – thus no anwers to your basic points.
Just a side remark: short as you are on panel space, why not relocate the headphone jacks? (at least, that is what I take the two grey circles in the lower right to represent). The panel is not the best place for them anyway, far better to have them on or near the turtle deck, unfar from the headset wearer’s shoulder.
[[and a bit off-topic: how are we still going to have to do with those old-fashioned jack plugs, the microphone one of an exotic sizing? When will we have a single jack with multiple rings, like in consumer electronics, but of course of much better reliability? And that jack a bit smaller, too, perhaps? ]]
Jan_Olieslagers wrote:
Just a side remark: short as you are on panel space, why not relocate the headphone jacks?
Good point- I could put hem near my head on the turtle deck. I think maybe I have seen someone done that on the Sonex? My thought was to have them close to the radio to minimize noise, but that may probably not be an issue.
If you use shielded cable, even of less than superb quality, there should be no noise issue. On my little plane, the leads to the magnetos are not shielded as they should be, yet noise on the comms is never an issue. And the shielded cable used for the headsets is absolutely not of superb quality – but it is ok, very much ok.
Jan_Olieslagers wrote:
and a bit off-topic: how are we still going to have to do with those old-fashioned jack plugs, the microphone one of an exotic sizing? When will we have a single jack with multiple rings, like in consumer electronics, but of course of much better reliability? And that jack a bit smaller, too, perhaps?
This has been invented for planes as well. 
The Zlin 142, for example, has the single jack version.
Find room for a couple of USB sockets, I suggest.
Will the 7” version of the G3X not fit? These don’t seem very popular, but give all the same functions as the larger version, including radio/transponder, PFD/MFD.
You could also consider dual G5’s. They are fairly cheap, there is a dedicated HSI mode that you could run on the second one to give less cluttered information, and it’s a backup if needed. I bet they will add extra screens in future too.
Personally I would not install a phone/tablet in the panel, I prefer the look of “proper” avionics, and wouldn’t want to have to redo a panel when my new phone has a different form factor. Instead maybe create a neat and compact mount for a phone for the occasions when you need it permanently available (eg tricky VFR airspace). Freeing up permanent panel space for something else.
The second design looks best in terms of the alignment grid and symmetry of the layout.
The places marked “USB” (in big red letters) are for USB (“Charge2” from a guy in the UK, baught it half a year ago). I need one for the Nexus (or future devices) and one spare. The nexus itself is only hold in place by velcro. There is no space for anything larger, and the panel itself is easy to make from scratch in the unlikely event (chances are, at least in 10 years, a new EFIS will replace any old one, and the panel has to be redone anyway).
Two G5s wont really help, as they are simply too small for everyday use (at least for me), too much information cramped in a 3.5 inch screen. As a backup and as a AI/HSI for everyday use it’s perfect.
It has to be MGL EMS in any case, and my plan has been the iEFIS, then I don’t need the stand alone EMS. The iEFIS is a touch screen device.
What I was wondering about was more the backup “philosophy”. With a battery operated extra GPS (Nexus), is a full primary display backup just a “nice to have” feature, or a necessity? I feel it’s more on the nice to have side of things, but I’n not sure.
In terms of backup, I think that a conventional altimeter+ASI is preferable over, say, a G5. There are lots of “pure glass” panels these days but it seems a bit crazy to me to create a panel that requires electrical power even just for airspeed and altitude. When conventional instruments need zero power and just a pitot-static system, and nothing at all besides a cabin static source in the case of the altimeter.
The G5 only really comes into its own when integrated with Garmin air data, nav source, autopilot, etc so not sure it fits well with your MGL architecture?
Your layouts with 2x MGL Xtreme EFIS look good. But preferably with them side-by-side or stacked. Can you fit one above the other in the centre, it looks tight?
One thing I have noticed on homebuilts is that they tend to group each switch with a CB right next to it, whereas in other aircraft you have the switches where you want them, and the CBs are grouped all together so you can check in one glance if any CB has popped.
In the above layouts it seems OK however because all the switches, and therefore all the CBs, are more or less in one place. But I would still group the CBs together because there will be circuits which will need CB protection but won’t have individual switches.
Certainly have USB charging sockets (with the intelligent charger circuit behind them; not just 5V going to the two pins because loads of devices won’t draw current from that, and if they do they draw too little to power them or charge them) but maybe not in the panel because then you have leads running at a high level where they will get in the way. I would have USB sockets near my knees i.e. in the side of the aircraft, or in the centre console. In flight, there should not be any wires in the way.
