Matt's Latest Instrument Panel
Using Graphics CAD To Layout Panel
I used a program for Windows call Micrografx Designer to layout the panel. It is a full-featureed graphics CAD program that has everything you need to create very accurate drawings and export AutoCad DXF files. Using a micrometer, I measured the exact dimensions of each instrument and proceeded to draw a replica of the instrument in the CAD program. Areas that were to be cutout and did in black, bezel outlines in red, and description text in purple. After I was satisfied with the layout of a given instrument, I used the "Group" function on it so that I could then drag it around on the virtual panel as a single entity.
Once I came up with a layout that I thought might work, I printed it out in 100% scale using the "Tile Print Mode". A sharp scissors, some scotch tape, and in a few minutes I had a paper mockup of the panel that I could attach to the airplane. Interstingly, what looks good on the computer screen doesn't always look as good (or fit as well) in the airplane. I found that I had to move things around a bit to account for the Canopy Frame that blocks about 1 inch around the top of the panel. Also, this was a good time to give some thought to ergonomics. For example, holding the stick with the right hand, can you adjust everything easily with the left hand?
Once I was happy with the layout, I used the Export DXF function of the CAD program to output a data file. I emailed this DXF file to Steve Davis of The Panel Pilot. A couple of weeks later I received a beautifully CNC machined Plexiglas mockup of my Panel!
Speaking of Steve Davis and the Panel Pilot, Steve also offers a exceptionally nice Fuel Cap Engraving service where he will engrave the octane requirements into your aircraft fuel caps. I find this particularly nice because I then don't have to put those cheesy circular octane stickers around the fuel tank filling ports. I sent my caps to Steve and received them back in a week or so as shown in the Fuel Cap photos. A very nice service that is quite affordable and one that I would highly recommend.
First Trial Fit Into Plexiglas Mockup
Now its time for the first big test. How does everything fit? Nearly perfect, actually. The only problem I had was with the Transponder as it has a number of 4-40 screws on the bottom that I didn't account for in my dimensional mesaurements. I used a rat-tailed file and made a few 'adjustments' to the Plexiglas, and I was on my way.
This ability to easily make changes to the panel is a really nice feature of Steve Davis' process. Steve will make Plexiglas mockups until everything is just right before cutting on the real panel. I have been making dimensional notes whenever I find something that doesn't fit quite right. I then go back to the CAD program and make the changes.
Constructing Support Brackets Using Plexiglas Mockup
Because the Plexiglas panel mockup is clear, it allows for easy alignment and design of the necessary support brackets for the various radios and instruments that don't directly mount to the panel with screws. This is my third panel for this RV-4, and I can without a doubt say that using this Plexiglas mockup method is far easier and more importantly, substantially more accurate. Best of all, the holes are all perfectly round or square and match the instruments perfectly. And the screw holes for the round instruments match up beautifully!
Radio Stack Supports
I found that I had put the Transponder and Transceiver a little too close together and that the holes for each were a little short because I hadn't accounted for the flanges on the trays sticking through the panel. With the Plexiglas mockup, it was easy to see just what needed to be enlarged and it was then easily filed out to the proper size. Any changes to the Plexiglas mock up are noted on the CAD program for Mockup #2 later.
Other Supports and Switches
I had to modify my support bracket behind the instrument panel for a second time with the new layout because I had placed the radios so low in the panel. I had already modified this bulkhead on the previous version of the instrument panel, replacing the .032 bent sheet with a single piece of .75 angle. This served two purposes. The first was to increase my knee room by over 2". With my feet on the rudder peddles, the tops of my knees bang right on the bottom of this bulkhead; certainly not the most comfortable position. The second reason for switching to the .75" angle was to build in something strong in which I could support the weight of the radios. This new piece worked out well satisfying both requirements. I did find I had to modify it for this new panel, though.
I cut out a deep .25" right out of the top of the angle to allow the radios to fit down correctly and assure that the angle of the instrument panel and the radios was correct. Cutting the piece out left my sturdy support pretty weak though. I added another angle facing the other direction and cutoff .25" of its bottom. Strength restored, knee clearance maintained! The photos here show the replacement bulkhead, and supports for CD Changer, uMonitor, Radios, and GPS. Note that I had to move the Intercom to the right to make room for the ELT panel I had forgotten on the first CAD layout. Yeah, was I glad this was just the Plexiglas mockup!!
Plexiglas Panel Mockup #2
Okay! All of the radio supports are done and I can't believe it but, everything seemed to fit in my tiny, cutdown RV-4 panel! I was able to build what I think will be adequate supports for all the 'sticking-out' things in the panel. Modifications to my original layout included making the Transceiver and Transponder holes taller and adding small notches in the corners of both to allow the case screws to fit through, moving the adjustment screws for the VCard Compass up and to the right by about .125", moving the Intercom to the right, adding a big hole for the ELT remote control, and adding a couple of odd sized holes for the EGT and CHT rotary switches on the far left. All in all, not that many modifications, but far more than I would care to have to cut another panel by hand! Ack, think about it.
So, its back to the graphics CAD program on the PC with my Mockup #1 Plexiglas panel in hand and micrometer and a ruler close by. I carefully measured all of the changes I had made to the Plexiglas Mockup and reflected these in a Version 2 of my CAD drawing. If you click back and forth between the "CAD Version 1" and "CAD Version 2" photos on the right, you can see the modifications between the two versions of the panel.
When I was sure everything was just right, I generated a DXF export file of my new Version 2 CAD drawing and emailed it off to Steve Davis of The Panel Pilot. Two days later I received an email from Steve telling me that my Plexiglas Mockup #2 had been cut and was shipping out the next day. He included the "CNC Cutting" photos on the right showing just how my Plexiglas panel was cut on his Gantry CNC Milling Machine. Very cool. When I look at these photos my mouth hangs open as I recall how I labored for days cutting my first two instrument panels with about 50 Dremel Cutting wheels and some dull files. Not only is it a lot easier to sit at my computer and layout my panel in a CAD program than it is to cut all that metal by hand, but the end product is far more accurate, straight, and well, just plain awesome looking! :-)
The new Mockup #2 arrived in excellent condition. If you compare the photos "11. Modified Mockup #1" and "12. New Mockup #2", you can see the changes that were made in the first Mockup to make everything fit correctly. Once all of the instruments were reinstalled into the New Mockup #2, it was obvious that everything fit exactly as planned! Well, actually there was one small area that wasn't quite big enough. A small modification to the CAD drawing was all that was required and a new Mockup wasn't necessary. onto the Real Panel!
The Metal Version
Coming Soon!