CAD for days …
I hadn’t gotten very far into the process of putting the radio interface together when I hit my first problem. I’d purchased a dual rotary encoder with the hopes of using it as a frequency selector. I wired it up as suggested, and it worked briefly before one stopped working entirely and the other skipped forward or backward randomly. I tried rewiring, swapping pins in both the code and on the microcontroller, trying different pieces of code … nothing worked. I eventually sent the encoder back to the company for a replacement. Upon receiving the replacement, I had the same problems. It would work correctly at first and then slowly start deteriorating. Seeing as how I was using their code and it always functioned at first, I gave up on that encoder and temporarily shelved the radio interface project. Somewhat frustrated, I began working on the rest of the simulator design.
I decided to start with the C90’s instrument panel, which was where the second problem presented itself. Getting a clean image of an aircraft’s instrument panel is somewhat difficult. Most images seem to have something in the way. A yoke, the pilot’s seat … just something obscuring a clear view of the entire panel. Eventually, I came across a Beechcraft parts manual detailing all of the various panel layouts of the aircraft. With this new information in hand, I began modeling the panel in LibreCad, an open source 2D CAD drawing program.
The first step was to clean up the original image, remove leader lines and numbers and create a single image I could then import into LibreCAD. With a bit of work in Photoshop, I was able to get that done fairly quickly. Next up, figuring out LibreCAD. I then imported the reference image. The first thing I noticed was that the image was over 1000 x 1000 inches in size. I could not figure out why that was and to make it worse I couldn’t figure out the scaling tool. I later discovered that the image was simply being imported with the pixel size as its dimensions. Additionally, the scaling tool turned out to be a ratio of the old dimensions to the new ones. e.g. If I wanted a 10 x 10 box to be a 15 x 15 box, I’d enter a 1.5 scaling ratio. This was, of course, figured out after I had already traced out the entire design.
The next step was to take that cleaned up image and trace over it using the CAD tools, creating a blueprint for the panel. This … took a lot of time. And I’m actually still going through the process as I write this. The main challenge is deciding what to draw and what I could leave out. Switch holes, Instrument panel cutouts, labels … there was a lot of detail in that original image and sorting out what I needed and what I didn’t was a fairly involved process. Although I only needed the instrument panel cutouts for the instruments, I needed to actually make the hole smaller because the instrument bezel actually be glued to the panel rather than the instrument as I was going to be using an LCD display. Switches that weren’t going to be used still had to be drawn as they helped postion the ones that were. Additionally, while I had engineering drawings for the main panel, I had no reference for the subpanels (The area below the instrument panel with the switches and where the yoke comes through). Solving that problem took some creativity. I pulled the original texture files from the X-Plane C90 and worked with them in Photoshop to cut out the relevant areas. This was followed by redrawing them in CAD at the original size. I then painstakingly resized them until the matched the instrument panel I had already created. This was perhaps the most frustrating part, as the two drawings came from different sources and weren’t necessarily the same scale or shape. That said after smashing it with the proverbial hammer I managed to wind up with something that actually worked rather well
Another hurdle I had to overcome was the size of my LCD panels. Although the instrument panel may have been 12 x 15 inches, my display was only 13 x 11. Which meant that all of my instruments had to fit within that area regardless of how much panel space was available. This took a lot of shifting around of instruments and in some extreme cases, resizing the image to fit within a smaller area. At this stage, I’m fairly happy with the placement of the main instruments but I feel as though some of the wasted LCD areas can be utilized. I have to be careful though … I don’t want a cluttered panel.
The process is still ongoing but I’m getting really close to being done with the design. I’ll need to design an annunciator panel, insert the screen reference for the engine instruments, and adjust the engine instruments themselves. Once that’s done I will be printing it out (Turns out OfficeDepot will print full-scale engineering drawings) and check the dimensions. After that, I’ll start the build process. In other news, I’ve already gotten the 17″ display and it works beautifully. I’ll be purchasing the 15″ display sometime this month so that I can confirm it’s dimensions. I’ll continue to post as I progress.