F1 Rocket, Vans Aircraft, Homebuilt Aircraft Parts, Harmon Rocket

EFIS...Electronic Flight Instruments. Like every pilot I want a moving map display. A quick search of the moving map display market is enough to make a person sick. Prices for these things vary from a staggering $2700 for the Sky force IIIC to a blistering $7000 and up for tiny panel mounted Multifunction Displays. To pay this much money for a screen the size of a playing card is insane. The best you get is limited topographical features, and a data base of airports and navaids. That's it! What a rip-off.
So I have always thought the idea of an onboard computer was really cool. Imagine all the functionality of a high powered desktop PC packed into your go fast airplane.

This dream has led me to the quest of someday claiming victory and thumbing my nose to the giant avionics manufacturers as I beat them at there own game for a fraction of the cost. My goal is to have a high moving map display with serious terrain display like a moving sectional chart, to be able to listen to my vast mp3 collection in flight thus eliminating the need for a CD player and to watch in-flight movies...yeah that's right...in-flight movies in hifi stereo in a big screen under my nose.
Its going to happen! With the current state of PC technology, all these things exist NOW. So consider what has to happen to make this all work.

1. Build a small light weight computer.
2. Make it stand up to the heat that builds up in the cockpit of a small canopy covered aircraft.
3. Make it endure the vibration of a 260 HP engine.
4. Make it run off 13.8 volts at a reasonable amount of amps
5. Be able to user interface it in flight (forget a keyboard)
6. It must be able to update software easily.
7. It has to have a display you can see in the sunlight.

Wow....that's a lot of stuff, but all seem attainable. Lets start with the first...Make a small light weight computer.
To squeeze this thing behind the instrument panel of my F1 Rocket, it has to be small. I thought of a lot thing including cannibalizing a laptop, but that would cost a ton of money, might not work, and be nearly non-repairable. I wanted a computer I could, build, fix and upgrade myself. A quick trip to Fry's electronics in San Jose Calif led me to the present choice of motherboards. I selected the Micro ATX form board because of its small 8" x 10" size. The cost was right at $79, and it had onboard AGP video and sound devices. It is capable of driving from a Celeron 400 to a PIII 700 CPU. I went with the Celeron 466 because it was inexpensive and still overkill for what I was going to use it for. Next came the mass storage device. I selected a 3.5" Seagate 40 GB IDE drive. Again, lots of power for $89 bucks. This size will allow me to store 2000 mp3 songs in 6 GB, the OS , the map software and still have room for nearly 6 hours of DIVX movies for in-flight entertainment.

Here is the computer operating on my workbench. When finished it will be 8.25" wide, 18" long and about 4" tall tapering down to 2.5" at the other end. If you look at the picture, you will notice the power supply at the top of the picture near the fans. This was a desktop 250 supply and has been stripped of its metal housing. The power leads were removed or shortened to tidy things up. The later CPU technology allows for lower voltage CPU cores and as such this thing uses very little power. The CPU is cool to the touch as are all other components in the motherboard. The power supply is only slightly warm without the fans and with the fan blowing on it, the temp is cool.
So how to run it of 13.8 Volts.

The obvious choice is a multi voltage, high amperage DC switching power supply. FORGET IT. Way to much work. I tried an inexpensive inverter and to my amazement, the computer operates perfectly on less than 5 amps.. Whew. The inverter will be stripped of its housing to reduce weight and its parts will be installed in the computer box so it'll be cooled by the fan airflow. At 90% efficiency, I expect this computer will draw 8-10 amps from the DC electrical system.