After reconsidering carefully (or just following the example of oh so many wonderful blogs out there), I decided to move the page to the blog. This way I also get to tag it, which makes searching and categorizing much easier once I have created a few more entries. So here it goes:
I had this half round table top from Ikea (they seem to have changed the size, though), which I used with three kitchen legs (also from Ikea) as a cheap monitor stand. The stand got replaced by a more fancy arm that I got from Konrad and so I wanted to put the table top to a new use. As a father, computer scientist and aviation enthusiast, the first thing I saw in it was a cockpit panel to play with for my
The panel I had in mind was supposed to have a standard T arrangement (air speed indicator, altimeter, attitude indicator, compass, turn/slip indicator and variometer,) along with a landing gear lever and a few switches for batteries, lights and such.
Attitude Indicator (AI)
Due to the (assumed) complexity of it, I started with the AI. It later turned out to be much easier to build than expected, but isn’t that the case with most challenges?
The first idea was to have a sphere rotate along the longitudinal and lateral axis to have the highest freedom of movement possible. But when reading through a few pages about the technical details and design of the instrument, I found that most of standard (non fighter jet) aircraft using a classic AI would have a limitation of +/- 27° pitch and +/- 60° bank and thus a sphere would be a little bit of an overkill. I also wanted to work with the material I had at hand and for driving the AI it was two Hitec hs-55 servo motors.
In the second attempt I started from the casing of the instrument. I had this old Altimeter lying around and derived the dimensions of my instruments from it. The frame should be a 83mm square, and the tube… Well, I found the perfect match for the tube in an old potatoe chips can, which has the exact same diameter as the tube the altimeter was installed in: 75mm. Based on that, I chose the frame rotating around the longitudinal axis to be limited to 74mm, giving 1mm of space. A cover ring around the outer rim to hide the edges also left enough space for another very simple solution: a toilet paper roll with each the diameter and length of 45mm to rotate around the lateral axis. To save some space, I decided to install the servo inside the roll, attaching it to one of the lids of it.
Another part I wanted to use for the instrument was an Arduino Pro Mini clone. With its small footprint and easy way to program (the Arduino IDE comes with a servo library), the hardware part of the AI was finished in half a day only.
Hooking up the servos is pretty straight forward, you can find plenty of exaples all over the web, so I won’t re-invent the wheel there. The example coming closest to my setup might be this.
The software can be found in my github repository.