Step 1 - Main Design My electrical system is a single-alternator, dual-battery configuration with a manual battery switch. The batteries are identical 20Ah Panasonic batteries, installed just behind the front seatback, on the floor. The battery switch is a Blue Sea Systems 9002e, a 4-position marine-rated device with alternator field disconnect. This is a very simple setup with only a single bus to worry about. I printed out a full-size, color copy of the current instrument panel design, then cut it out and taped it onto the panel. Looks pretty good! Do you want to do the same thing yourself? If so, click here for a synopsis of how I used Inkscape to do this! You can also Click Here to download an SVG file of my panel template. Download Inkscape (it's free!) and use it to open this file. The panel is to scale (actual size) and per plans. That means you can import (File->Import) pictures of avionics/instruments, set their widths/heights in the top toolbar, and play with their locations on the panel. It's fast and easy - no need for a panel builder! Step 2 - Main System Wiring The batteries and main switch are installed. The plans call for batteries either in the nose or above the spar. In the nose requires less ballast for solo pilots, but limits your weight and balance range if you fly with passengers. Above the spar gives you more flexibility, but flying solo you have to ballast the nose all the time. I went with a middle-ground solution - behind the front seat back! I'm a relatively light pilot (less than 160lbs, depending on proximity to Christmas), and the weight of my batteries more or less right behind my butt just makes me a heavier pilot. I'll still need nose ballast, but maybe a FEW pounds less, so I might save a few bucks in gas over the long haul without sacrificing much CoG range. But the real reason is noted above - my design has a manual battery switch, which eliminates the load from the main contactor(s). It's located in the middle of the front seat back, about where the fuel valve would normally be placed. I don't need a fuel valve there because I have a Mazda Rotary (see the engine chapters for details). One battery is behind each seat, for redundancy. The switch connects to a fuse panel just below it (easy access), and there is a grounding panel just behind the pilot's battery. You can see a lot of grounds here because I'm using a single-point star configuration grounding system, which helps eliminate noise. Larger cables run back to the firewall, where it will connect to the alternator and the starter contactor. I still need to make upper covers for the batteries to prevent them from sliding out if I'm ever inverted (such as during a crash), but otherwise this system is basically done. 2009-05-21 (0.50 hours): First switch installed OK, it's a minor bit of progress but an important one to me. Until now I've kept all my switches and wires and such on a small temporary panel. This let me work on things without actually installing them, but was sort of an anti-commitment thing, too. This switch controls the speed brake - I'll install the landing gear switch next, but I need to rewire the interface because I want to remove the AEX unit. I'm not happy with how that thing behaves. 2009-07-02 (5.00 hours): Gear Switch I know it doesn't seem like a big step, or something that should have taken this long. But today I installed the switch for the Wilhelmson nose gear lift. Several years back, when I purchased this unit, I also bought the AEX1 auto-extension module. I quickly came to hate it - every time I turned on the power, it wanted to extend the gear, and nearly caused several accidents in the build process because of that. And I didn't like the standard answer of adding a breaker or switch - what good is a safety device that you can disable? This also came with a big rats-nest of wires, some of which didn't even match the supplied wiring diagram. For instance, "white" for me was actually grey. Blue was purple. It took a while to wire, and it looked like a mess. I never did get it neatened up to my satisfaction. Today I cut all the wires out of the rats nest, removed the AEX1, and rewired the unit with the bare minimum of wires. I kept everything neat, bundled all wire bundles together with heat shrink tubing, and now I have a clean and simple installation that I'm finally happy with! The only thing I have left to do is replace the LED grommets - they're just sort of sitting there right now. I need deeper grommets for my instrument panel. I'll address all the LEDs at once when I do the full panel setup later. Besides, I'd just have to remove them anyway when I do my panel overlay (which I may do with carbon fiber trim sheets off eBay. 2011-11-27 (9.50 hours): Installing Avionics Avionics are something you usually leave until the last possible moment, because every month of the build brings new innovations (and price reductions). I'm glad I did - I started the build before Dynon Avionics existed -- even before Blue Mountain (remember them?)! But you can't wait forever because once you start wiring and laying out things like controls and switches you need to be able to plan the back of the panel. My panel has changed a bit since earlier "dreaming" posts (I still can't afford SL-30 radios), but I'm happy with it, so I decided to install a few instruments to get the ball rolling. The "quad" you see here are 2-1/4" instruments intended mainly to act as backups to the Dynon panels I will be installing. I chose these four units for two reasons. First, three of the four (compass, altimeter, and airspeed) require no power or vacuum at all, so they're obvious choices as backup units. Second, the electric turn and bank is a solid-state unit with few moving parts and no gyro to tumble. All of them are very light and make a nice quad together. I had hoped these units would install easily, and they did... sort of. The holes must be drilled very precisely, and even then I found slight variances in my instruments that I needed to work around - the compass had an adjustment-screw slot on the bottom, two instruments had top lighting bumps, etc. Thanks to Jim at RST Engineering for a nice set of downloadable PDF templates for this task! Step 4 - Overvoltage Module Jim Weir of RST Engineering was kind enough to publicly post a circuit diagram and documentation for a crowbar overvoltage module. This device basically shorts its power feed to ground if it sees a voltage exceeding a trip point. The idea is to put it on the tail end of a fuse or circuit breaker leading to the alternator regulator, the primary cause of overvoltage events. By shorting to ground, it blows the fuse or trips the breaker, taking it offline and preventing damage to the rest of the devices on the bus. (This all happens pretty quickly.) I decided to build my module based on Jim's plans, but made one change. I replaced all of the devices selected with equivalent surface-mount components. I didn't really spend a lot of time shoving this into the smallest form factor possible. For example, I chose size 1206 resistors to make soldering easy - why sweat for a quarter of an inch in this particular module? It's about 1.5"x1" even with four 5mm holes for mounting posts, so I didn't do too badly. I have one backside track, which can be replaced by a simple jumper wire, and only four holes (not counting the mounting holes). Bill of Materials: Designation Digikey P/N Value Description Cost C1 PCE3574CT-ND 10uF Electrolytic capacitor, 5000hr life $0.6360 D1 S1BDICT-ND 100V 1A Diode $0.48 D2 S1BDICT-ND 100V 1A Diode $0.48 D3 1SMA5918BT3OSCT-ND 5.1V 1.5W Zener Diode $0.40 R1 311-470ECT-ND 470 ohm Resistor $0.078 R2 311-10.0KFCT-ND 10k ohm Resistor $0.088 R3 P5C102CT-ND 1k ohm Trim Potentiometer $0.31 R4 311-10.0KFCT-ND 10k Resistor $0.088 R5 311-4.70KFCT-ND 4.7k Resistor $0.088 R6 311-1.00KFCT-ND 1k Resistor $0.088 SCR1 S4010DCT-ND 400V 10A SCR $1.64 U1 296-1014-1-ND Dual op amp $0.49 Total $4.87 The plan is to build this on a single-side PCB and pot it in epoxy, with space allocated for the mounting studs. It only has two wires, one to the bus and one to ground. I'll probably make a bunch of these all at once, so if you want one holler, and I'd consider making a few for people willing to cover my costs and shipping. And by all means, check out Jim Weir's site, he has a lot of very useful information for aircraft builders, and a number of great kits for DIY-ers. This device is really cheap to build. The $10.00 estimate would cover PCB, solder, potting epoxy, testing, and the need to buy 5-10 of some of the parts above (single single quantities are not always available, even through DigiKey - who wants to buy a single $0.088 resistor?) Step 5 - Install Instruments I've been playing with instrument panel layouts for a while now, watching the available options on the market evolve. This is where I am so far. Qty Description Cost (ea) Total 1 ASA Flight Timer $40 $40 2 Eyeball Swivel Vents $150 $300 2 Dynon NextGen EFIS $4000 $8000 1 Dynon 2-axis Autopilot $1700 $1700 1 2-1/4" Attitude Gyro $3300 $3300 1 2-1/4" UMA Airspeed $200 $200 1 2-1/4" UMA Altimeter $275 $275 1 PS Engineering PMA9000ex Audio Panel $2100 $ 2 Garmin SL30 NAV/COM Radios $3600 $7200 1 Garmin GTX327 Transponder $1900 $1900 1 RealWorldSolutions Engine Controller $950 $950 1 RealWorldSolutions Engine Monitor $475 $ N/A Miscellaneous Switches and Indicators $300 $300 Total: $26,740 That sounds like a lot, but this is also a dream installation. I can (and probably will) cut the number in half by installing less expensive radios, only one EFIS display, and no electric backup attitude gyro. Then, as funds permit, the remaining items can be installed or upgraded as necessary. Basic Backup Instruments My panel design includes a Dynon glass panel and engine monitor, a fairly standard radio stack, a top row of switches, and room for Rotary Aviation's EC2 control panel. There are four backup instruments included. Today I installed the most fundamental pair: the altimeter and airspeed units in 2-1/4" format. I knew for sure I'd be installing these because they don't even require power - they're a nobrainer, really. I was surprised at how light they were. I have a standard 3-1/8" altimeter, and it's easily twice the weight of the 2-1/4" model. Note that this unit is not the sensitive type. The Dynon install will include an encoder - this is just a backup. For the other two units I'll probably install a compass and a turn coordinator. TruTrak makes a cost-effective 2-1/4" option here.