Here's a walk through of my panel design. Everyone has different requirements and opinions, so this is not meant to be the gold standard!
1. Mission/Objectives:
VRF Day/Night/VFR OTT (VFR On Top in the Excited States). This requires a heated pitot.
VFR Night, mostly because the lighting required is useful for anti-collision during the day.
Rough-field/backcountry operations.
2. Simple and light. Minimize bells and whistles, because instruments are just a backup to your eyes.
3. Avionics development. I design custom avionics devices and need to be able to integrated these with a standard panel.
4. Copilot operation for my flying buddies.
What I came up with is shown below. It does compromise my objectives a bit, but should work well. Here is my decision making process:
- I can support two EFIS devices, but only need one. The second one will be replaced by an array of my customizable instruments (see huVVer.tech) for developmental purposes. They are very light and economical and will be perfect for copilot operations.
- Ignition switch toggles rather than a rotary switch, simply for aesthetics. The Ignition Advance switch allows me to select normal advance on the PMAGs, or a more conservative advance curve (for partial throttle climbs or break-in). I did this on my Rocket, very useful.
- The parking brake knob is located near the ignition switches because it is naturally a complement to startup or shutdown of the aircraft. It is the only knob located on the panel so that inadvertent operation is minimized.
- The cabin heat knob is located below the panel because it needs to be well separated from the parking brake. The alternate air knob is on the throttle quadrant, where it should be for engine operation.
- Above the EFIS is a LEVEL button (not really required, but nice to have) and a TRIM button/indicator for my custom designed autotrim system.
- I chose the Dynon suite of Intercom (similar to PS Engineering), COMM and Button panel. It's a nicely integrated suite and it frees up a serial port for my custom avionics six-pack. The button panel really helps with quick settings-- not strictly necessary, but keeps the eyes out of the cockpit rather than fussing with menus.
- The array of Klixon breakers are all pullable. This removes the needs for switches in some cases (disable autopilot or trim, for example) and minimizes connections and failure modes. The PMAG power testing is controlled by pulling these breakers as required.
- The Master Switch and MFD power switch are in their own grouping. These are normally controlled at startup/shutdown and keeping them away from the flight-group of switches makes sense.
- Below them are lighted pushbuttons-- one for IDENT on the transponder, and one for copilot PTT. The copilot PTT is on the panel next to the quadrant because I don't want any switches on the right stick which can be accidentally operated in flight (most likely by non-pilot passengers). For the same reason, the copilot TRIM switch is also on the panel. When the copilolt is flying, these switches are naturally in reach of the throttle hand.
- The bank of toggles are the flight switches. Some have combined functions, such as the Landing and Taxi switch and the NAV/STROBE switch. The light switches have a center position to FLASH (wig-wag) the light. The NAV/STROBE switch uses the center position for NAV only and the up position for NAV+STROBE lights. Finally, the HORN switch is a momentary operation. A horn!? Yup, if you need to clear people or animals off the runway/golfcourse/beach/sandbar/mountain strip you are landing on, it makes sense. Remember the mission!
- The ONSPEED control on the top right is for the ONSPEED angle-of-attack/energy managment system. I am part of the ONSPEED group and I will be incorporating this function into the S-21 to optimize it's STOL capability. I designed a custom display that will be mounted on a downtube in my line of sight.
- There are a couple of USB ports for loading EFIS data, and the required ELT remote. The USB port on the right is only required if a second SkyView EFIS is installed (instead of my custom instruments).
- Custom Instrument six-pack: I develop custom avionics and have released a very low cost family of micro-EFIS instruments (see www.huVVer.tech). There is a six-pack of these instruments planned on a removable panel. They will provide complete flight instruments and engine instruments for the copilot, all driven from the Dynon serial (or WiFi) data streams. I am also planning on reversionary modes so the the ONSPEED information can drive them (air data only) in the event of a primary EFIS failure. They would then provide a totally independent backup system. Since the cutout is identical to the SkyView cutout, I can always stick an SV screen in if I ever sell the airplane and the new owner wants a bog-standard system.
Finally, the entire panel will be removable and connectorized. That's one reason everything is held together with screws and I have mounted the throttle quadrant to the frame independently. I will have to release the parking brake cable and (maybe) the cabin heater cable, disconnect several connectors and the main power bus, but it will be possible (if not easy). Servicability is also enhanced, such as removing the bottom of the tunnel tray to gain more access to the switches and breakers. Of course, removing the EFIS screens helps a lot!