Cockpit Panel (Part 1)

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:

Basic Idea

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 myself kids.

Panel

Sketchup Model of a basic cockpit model based on the half round table top

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)

Hardware

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?

ArtHor 1

The first idea for the artificial horizon was to use a shpere

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.

ArtHor 2

Second design, a toilet paper roll in a chips can

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.

Software

The software can be found in my github repository.

 

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About Michael Melchior

Husband, Father, computer scientist, commercial helicopter pilot. Full of ideas and open minded, I try to see challenges in what others call problems.
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