Panel Design

I have settled on a design after giving some consideration to what are my actual requirements. Here is a summary of them.

Requirements:
• Primary flight display on pilot Center of View (COV).
• Secondary flight display adjacent to primary.
• Back up flight insturments grouped together.
• Radio stack right of Center of Panel (COP). Just like most Piper and Cessna airplanes.
• Ignition switch on left side to keep right hand free during engine start
• Switches logically grouped rather than spread across bottom of panel.

Note: COV is located 1.125" inboard of the left panel rib.

Avionics Trade Study
At this point I have already settled on the GRT EFIS and engine monitor. This trade study is to configure the Nav and Com radios.

Requirements
1. Approach GPS. Internal procedures from database.
2. ILS receiver
3. COM1 and COM2 capability
4. Back up Nav if primary fails.
5. If any one radio goes belly up, I still want alternate Nav and Comm.

Options
1. GRT EFIS, GNS-430W, SL-30
2. GRT EFIS, GNS-430W, SL-40
3. GRT EFIS, GRT GPS RAIM, GNS-430W, SL-40
4. Chelton EFIS, SL-30, SL-40
5. GRT EFIS, GNC-300X, MD-41, SL-30

Equipment Pricing (2009)
• GNC-420W - WAAS, Com $6,900 (Saves $1400 over 430W but then need to spend $2.2k more on SL-30 for ILS capability.
• GNS-430W - WAAS, ILS Nav, Com $8,300
• SL-30 - ILS Nav/Com $3,800 ($2,200 for ILS capability)
• SL-40 - Com $1,600
• GNC-300XL IFR GPS/Com $3,150 + MD-41 annunciator $900. Has ARINC-429 and RS-232 interface.
• GPS-400W - Same GPS as 430W but without nav and com.

Requirements Analysis

Antennas

The diagram of my antenna and coax runs are shown in the diagrams below. After I designed this, the FAA announced that they were decommissioning the ILS marker beacon system. I had already installed the antenna in the wing tip and run the coax down the wing. I am going to leave it there in case I find a use for it.

My antennas are very conventional. I am concerned about matching, shadowing and multi-path to the antennas. There are less visually obtrusive experimental (gamma match) antennas available but these is no engineering data available of their installed performance. All you get on the newsgroups is anecdotal stories of how it works OK, or seems to be fine, or I never had a problem. That is why you will see quarter wavelength whips and cat whiskers on my airplane.

The cat whisker is designed to receive both the localizer and glidescope signals from the ILS system. The glideslope is on the third harmonic of the localizer. The signals are separated for the receivers using a Diplexer -NOT A SPLITTER. A splitter divides half the received signal to each receiver. A diplexer takes advantage of the frequency separation of the signals and using filters provides all (not half) the glideslope signal to one receiver and all the localizer to the other. I am simplifing the description by not mentioning insertion loss of the filters.

I have dedicated comm antennas, one above and one below the fuselage. The transponder antenna is located below the copilot seat. Another common misconception about the transponder antenna concerns the 200 watt radiation from it. Do not worry about radiation from this antenna as you are inside a Faraday cage and there is a ground plane in between you and the antenna. Also the duty cycle is so low that it doesn't matter anyway.