Instrument panel and electrical

Perhaps one of the most significant accomplishments of the build is the instrument panel. The choice of avionics and configuration took several months, mostly because we were thinking about the panel layout long before we were ready to cut holes in the panel. As I started seeing the instrument panels in other airplanes during flight training for my instrument rating and commercial pilot training, I soon identified the good and bad designs. I took up the responsibility for drafting possible panel layouts on the computer using Solid Edge. My first draft was quite different than what our actual panel looks like. Certain avionics of choice were no longer available when the time came to purchase them, however, new and improved versions took their place. For example, the old Vertical Power VP-200 with its own screen was replaced by the VP-X, which integrates with the Dynon SkyView EFISs. Here's a complete listing of what's installed:

• Dynon SkyView 10" as the PFD. Includes Dynon Mode S transponder (mounted behind the 10" EFIS on the sub-panel) and backup battery
• Dynon SkyView 7" as the MFD. Has its own backup battery
• Vertical Power VP-X Sport electronic circuit breaker system (mounted underneath the panel)
• Garmin GNC255A NAV/COM (10W transmitter). Interfaces with the SkyView digital HSI via RS-232 connection. This interface also allows the frequencies selected on the radio to be displayed on the EFISs at the top.
• MGL Stratomaster Velocity EMS (monitors CHT and EGT probes).
• Flight Data Systems FC-10 fuel flow indicator. Fuel flow sender located in fuel line after electric fuel pump.
• Precision Aviation lighted vertical card magnetic compass
• Lighted analog engine instruments from Van's. Includes tachometer, oil pressure, oil temperature, fuel pressure, L/R fuel gauges, and manifold pressure. Instrument lights are spliced into the position light power pin on VP-X and dimmed via a rheostat on the panel.
• Switches to control power to devices (via programmed VP-X) with independent lighting circuits. Switches light up to indicate when device is on.
• Ameri-King 121.5 MHz ELT. Includes panel mounted control panel (this is not yet installed)
• Odyssey PC680 12V battery
• Plane Power 60A alternator
• Ray Allen flap position indicator and position sensor.
• Hobbs meter and oil pressure sensor with low oil pressure light on panel
• Cessna style battery master and alternator master switch
• Panel labels made using a Dymo label maker

Ultimately the best way to decide how to arrange the panel was to do a little artwork with permanent markers. Then we moved it inside the cockpit to see how it looked before cutting out anything.

A sharp fly cutter on an overhead milling machine makes quick work of the round instrument holes

Ouch! Where did all that come from!?

No worries, it looks worse than it really is. This picture was taken just before the panel was lifted inside the plane. All the longer wire bundles were first stacked on top of the radio tray. After moving the panel inside the plane, we pulled the wire bundles off the radio tray to let them hang underneath before screwing the panel in.

Now what do we do!?

The next step wasn't very enjoyable...We took turns organizing and sending the wires where they needed to go. Having labeled wires is what will really help you here. We have a combination of Dymo labels and masking tape labels. The Dymo labels however tend to fall off, leaving you with an unlabeled wire. Plastic tie wraps help to secure wires underneath the sub-panel (these are not permanent). Once everything was tied up, it was much easier to switch from tie wraps to wire lacing. Sore necks and backs are a necessary side effect of this job, but it does pay off.

A little while later and it looks much better!

Before flipping the switch for the first time, you must test the individual devices. This is done by connecting a 12V battery (a lawn & garden battery works fine) to each device and verifying that it turns on. A fuse appropriate for the device's power wire size (i.e. for an 18 gauge wire, use a 10A fuse) is placed inline with the test lead. With the battery grounded to the airframe ground, pushing the test lead into J10-1 for example should cause the device on J10-1 to come on. Do this for all the devices to verify that they don't blow the fuse and that the correct devices are in the correct pins on the connectors.

Using car jumper cables to connect the battery to airframe ground. Alligator clips connect the positive side of the battery to the fuse and test lead inside the cockpit

Alligator clips first connect to an appropriately sized fuse, then to the test lead (bottom)

Inserting the test lead into a power pin

The screen comes on for the first time when testing the PFD pin on the Vertical Power connector

The test lead inside the J12 connector

The heart of the electrical system is the Vertical Power VP-X Sport. It is this device which convinced us that DIY'ing a complex panel like this would be possible. By the time panel design was coming into play we realized we can work with sheet metal pretty well. The same could not be said for electrical work. Knowing the alternative was going to be a painstaking wire-by-wire installation process, taking advantage of the simplified electrical system installation using VP-X was the only way to go. In our installation, the engine ignition does not rely on the VP-X. The engine still uses dual magnetos for safety. Using the Vertical Power panel planner website, it allowed us to assign devices to power pins and print out the configuration sheet. Once finalized, you can create a configuration file on the panel planner website. The configuration file is loaded onto the flash drive that is included with VP-X.With the help of the Windows XP compatible VP-X Configurator application, you can program the VP-X with the configuration file at the click of a button. A standard ethernet cable links your PC to the VP-X.

Here you can see the schematic of the VP-X system with an old version (right) and finalized version (left). Scribbles on the old layout came about after realizing that certain power pins on J10 and J12 connectors have maximum current values. This meaning, you can't have an 18 gauge wire (which can support a maximum of 10A) pinned to J10-2 which can supply a maximum of 5A unless you know the device cannot draw more than 5A. Most of the time if the device draws a maximum of 5A then a 20 gauge wire will be specified, allowing you to use the J10-2 power pin. However, for some devices, the current draw is not specified; only the gauge of wire you are required to use. That means even if the device will draw less than 5A, if it is using 18 gauge wire and the actual current draw isn't specified, it should be on a 10A or greater power pin. Luckily there were just enough pins on the VP-X Sport to get all the devices assigned properly. This pin reassigning is what happened between old and new configuration pages.

All the avionics powered on for the first time after programming VP-X

Special crimp tool and power pins needed for J10 and J12 connectors

The VP-X with power pin connectors and main power wire (right) and d-sub connectors (left)

String ties were used to create all harness, they are gentle on wires, are more compact and  have a longer life than tie wraps and won't cut your hands when working behind the panel.  The transponder (gold box)  and backup battery for the Dynon display (black box ) are shown here.  Spiral wrap is used to prevent chaffing of wires. 

SkyView main wiring harness

Even with the VP-X, there still will be some tedious work within the SkyView connectors. That's because only a few of the wires go to VP-X. The rest have to do with the SkyView network...with connections going to other displays, the nav/com radio, and GPS receiving devices (on this installation, the FC-10 fuel flow unit). All the switches however (with the exception of the battery master) are quite easy to wire. They are simply used to signal VP-X when to send power to certain devices. A connection to ground is completed when turning the switches "on", and the VP-X interprets this and internally switches power to the designated device power pin(s). The same method applies for the flap and trim switches. VP-X even provides automatic runaway trim protection.

Switches on the panel are used to signal VP-X what device to turn on or off. It receives switch inputs through the J2 d-sub connector