New Panel Design - Critiques Please

Radios

At this point I'm going to be using a Garmin SL-40 (the COM-only version of the SL-30) and a VAL Avionics COM 2KR (a remote-mount COM transceiver). I have code to remotely control both of these from the EFIS.

I was contemplating using VAL's NAV 2KR for VOR / LOC and GS, but I've recently heard of several people working on SDR-based NAV radios. I'm not enough of an SDR guru to code my own, but if there's a project out there that has working code it could certainly be incorporated into the system.

The final installation will have dual FlightBox units, and I was considering using the SDRs in the backup FlightBox as a receive-only COM source (monitor ATIS, etc.) but with two working COMs, that really doesn't add much value. Using it as a NAV receiver would be much more interesting.

Progress

Got the newly cut and coated blanks (I ordered an extra one for a table-top demo) on Friday. Here's a shot of one with the switches installed:



I already had the Carling rocker switches with the custom covers, so I decided to just push ahead with them. Probably not as good or as small as the locking switches, but they were paid for and they should do the job. I think they look pretty good.

The cut-out on the far right is for the breaker panel. Decided to stay semi old-school and use standard Klixon breakers. The airplane already has 17 which are in good shape, so rather than trying to go in a new direction I just expanded it a bit. The new breaker panel will mount from behind so if I ever want to remove the panel I can do so without disconnecting all those breakers. Just take out the screws and pull the main panel away.

I should have new mounts for the iPads soon. I designed a new low-profile mount that won't take up too much space and will make it easy to mount the "knobs and buttons" bar at the bottom.

If you're going to be at Copperstate in Buckeye AZ next weekend, look me up. I'll be in the exhibit tent. I plan to have the demo system set up and running.

ssokol said:

I already had the Carling rocker switches with the custom covers

Click to expand...

I heard that rocker switches don't age well if they are driving any larger current loads. Evidently, they arc a bit inside.

I used Carling rockers too, but I mitigated this by having them only drive VPX circuits (milliamps pulled to ground), and let the VPX drive the load.

Are any of your circuits driving heavy loads directly? I'm curious if you had heard that about rockersas well, and if you are doing anything to deal with that.

Carling switches

At this point the only switch that's likely to have a significant load is the avionics master. I could mitigate that by using a separate contactor, but that seems to be trading one problem for another - adding another point of failure, adding at least one amp (the contactor), adding weight, more complicated wiring.

The switches are rated at 20 amps and the normal load on the avionics bus is less than ten. (You could push it as high as 15 if you connected three completely dead iPads and transmitted on both COMs at the same time, but that's not a very realistic scenario.)

The only other high amperage circuit is the landing light. I plan on upgrading it to LED some time soon.

This is a VFR panel and 99.9% of my flying is daytime, so I don't think I'm pushing things to use these automotive-grade switches.

Steve, what are you using for a power supply to feed the iPads?

Power for iPads

I have four options depending on what's needed. My system can either be purely wireless (the iPads talk to the flight data network using Wifi only) or wired (the iPads use an adapter to connect to the wired Ethernet network). Wifi only is quicker and easier. Ethernet + Wifi is redundant.

1) Power and Ethernet over Apple's Lightning Connector

Until the release of the iPad Pro 11 and 12.9 late last year, all modern iPads used Apple's Lightning connector. To be able to charge and to have a wired connection to the Ethernet network, I use an adapter and cable from a company called Redpark. The adapter provides enough juice to keep the iPad topped off and at the same time converts between standard gigabit Ethernet and Lightning. The ship's power input is a direct connection to a breaker on the avionics bus.

2) Power and Ethernet over USB-C

The latest iPad Pro models use USB-C. I'm still looking for the best option for this. There are adapters / dongles that do both Ethernet and USB-C power delivery, but I have yet to find one that I really like. Most have power inputs that are also USB-C so I then need a 12v (ship's power) to USB-C adapter which connects to the dongle which then connects to the iPad. Too many adapters / dongles / converters. If I can't find a better solution I may end up designing my own.

3) Power Only - Lightning

In this case the iPad is only connected to the avionics network over Wifi - no Ethernet connection. For this scenario I use a standard 12/24v to USB adapter and a rugged Lightning cable. My current adapter of choice is the 4.8 amp (at 5v) unit from Blue Sea Systems.

4) Power Only - USB-C

This is another TBD. Power over USB-C is a more intelligent process than power over classic USB and Lightning. I could just use the Blue Sea 4.8 amp charger and a USB to USB-C cable, but that limits the amount of power as the Blue Sea doesn't have the smarts to negotiate a higher amperage. Until somebody comes out with a panel mount USB-C charger, I may have to use an old "cigarette lighter" socket and a USB-C car charger.

Very interested in how well you can actually see those screens in a bubble canopy RV in the various lighting conditions since the screens will be fixed. I find it difficult (even with the latest Ipads) to see them in many of the conditions we experience in flight.

Watch out for temperature on IPADS

I've had issues in California with the Ipads turning off at very inopportune times because they get hot. It happens quite frequently in the summer. In RV cockpits, the great view we have also means the sun is blazing in from all directions, heating the ipads quickly. I'd recommend at least one of the purpose built Garmin portables or panel mounted products to make sure you have a working panel in the summer.

Sarah

Putting the experiment (or perhaps just the mental) in experimental

I do recognize that there are some risks to flying with iPads, and heat is by far the biggest. That's really the most experimental aspect of all this, and something I intend to figure out this coming summer.

The mount system that I've put together holds the iPad(s) so that there is a 1/4" space between the panel and the device. Behind the panel is a 70mm cooling fan capable of blasting about 33 cubic feet per minute across the back of the iPad. If that's not enough I can expand the hole and go with a larger fan.

As a Plan B (or really more of an extension to Plan A) I may try attaching a heat sink to the back if the iPad. It's already aluminum and does a decent job of dissipating heat. A heat sink pressed to the back could easily triple the amount of surface area, making for better convective and radiative cooling.

If all else fails, I can add blast tubes off the NACA ducts. (Probably would need to put some sort of damper on that to keep from freezing yourself in winter.)

From my previous testing, iPads shut down when the temperature of the device (not just the air around the device) gets above 100?F. So far I've put about 80 hours on the iPad in the RV without getting up to that point. (Truth in advertising: I do have a Koger sun shade that I'm sure helps a bit.)

Side Note:

I'll have the demo panel and a working unit in the RV (on a RAM mount) at Copperstate next weekend. If you make it in, please stop by the exhibit tent and say hello.

ssokol said:

As a Plan B (or really more of an extension to Plan A) I may try attaching a heat sink to the back if the iPad. It's already aluminum and does a decent job of dissipating heat. A heat sink pressed to the back could easily triple the amount of surface area, making for better convective and radiative cooling.

Click to expand...

This was going to be my suggestion as well... A finned plate, with the flat surface against the iPad and the fins running across the opening with the fan would allow a lot of air to be pulled through. If you duct it properly, the warm air off the iPads could be routed through vents in the glareshield and give you a rudimentary defroster/defogger for cooler weather... Or maybe run the fans the other way and use the warm air to heat the cabin.

Or you could use...

Or, you could incorporate a Peltier Module to move the heat from the iPad into the surrounding air...

Peltier fridge to the rescue...

Yep. I guess that's the true last resort. They're apparently cheap. You can get a complete thermoelectric refrigerator for $33 from Amazon:

https://www.amazon.com/Gourmia-GMF600-Thermoelectric-Fridge-Cooler/dp/B00DQT2ZGE

I just watched a video of a guy repairing one. Apparently the cooling plate will run off of 12v - 14v drawing something like 3.4 amps. Chances are you wouldn't need to run it for very long or very often (i.e. low duty cycle) to keep the iPad at a comfortable operating temperature.

The fridge includes the Peltier plate, heat sink, cooling fan, the plastic housing, and a 120/240 transformer. Obviously the housing and the transformer won't do much good in an RV. If the whole thing is $33 (including the shipping), I wonder what the useful bits cost, and how to find the factory.

ssokol said:

If the whole thing is $33 (including the shipping), I wonder what the useful bits cost, and how to find the factory.

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For $33, who cares? Just buy it, rip it apart, and use what's inside. You'll waste more money in terms of your time than you would save by finding the factory and trying to negotiate the purchase of a unit.

For a one-off...

that's fine. If I decide to offer a cooler as an option for the EFIS, I don't want to end up with a huge pile of dead coolers. I'm in California - that would probably be some sort of capital crime.

I did order one to see if it can be made to work. I'll post pics when it arrives.

I’m a BIG fan of the iPad pro’s, but I’m not sure I’d be comfortable with an aircraft that cannot be safely flown without them, or that relies completely upon air data being successfully sent to and properly interpreted by them. The thought of some glitch in an iOS upgrade causing a mis-rendering of that info on all three ipads at the same time is a bit disconcerting.

Suggestion by others that you restore a radio stack of some sort would also allow room for the one inexpensive and marvelously capable panel-mount instrument that would give you everything you need to cross check what the iPads are telling you or allow you to fly your airplane just fine if the iPads were stolen or lost when away from home. Most have probably guessed by now that I am talking about the Garmin G5. I hope you will consider it- very lightweight even with the optional 4-hour backup battery, and it puts the capabilities of an entire six-pack of steam guages into a single 3-1/8” cutout.- Otis

Hartstoc said:

Most have probably guessed by now that I am talking about the Garmin G5. I hope you will consider it- very lightweight even with the optional 4-hour backup battery, and it puts the capabilities of an entire six-pack of steam guages into a single 3-1/8” cutout.- Otis

Click to expand...

For only a little more panel real-estate, you could put a Garmin 660 in instead. Sure, you'd have to fly off GPS derived data if everything else went TU but that's do-able... And you'd have a backup map. Add one of the GDL boxes and you'd have AHRS as well (or maybe Garmin will do something that lets a Stratux provide that data).

Peltier Cooler

I received my $33 thermoelectric fridge today and quickly disassembled it. Turns out there's really almost nothing to it. A 120v power supply that outputs 12v. A 12v input. A switch that reverses the polarity (it can also be a warmer).

The important bits are:

• a large aluminum heat sink;
• a small (about 2" x 2" x 0.125") Peltier cooling block;
• a nicely milled aluminum mounting block with a thermal switch;
• a 12v fan

There's a small PCB with a power and mode switch (Cool - Off - Warm), status LEDs (one for cool / one for warm), the 12v input, and connections to the Peltier and the thermal shut-off. If I'm reading the circuit layout correctly, the thermal switch only works on the hot side. If that's the case, all I really need to do is power the fan and the Peltier from 12v.

Form-factor-wise, the mounting block is almost small enough to fit through a 2.25" mounting hole. A few seconds with a file and it would fit. It extends far enough that it would be easy to have the heat sink and fan behind the panel with a simple metal plate mounted to the block on the front side. I temporarily mounted a small aluminum plate and after about five minutes the temperature had dropped to the point it was uncomfortable to touch. Certainly cool enough to drop the temp of a hot iPad.

This is a good starting point. I think I can probably cook up a design that can mount in an airplane and keep things running in even the worst of hot days.