Monday, October 28, 2019

Inventory time

Apart from what's in N291DR at the moment, I hope to build 2 more Airball systems. This the inventory of components I have so far for the two probes and displays:

Stay tuned as these get built up. It should be possible, I think, to show the work being "kitted up" much more clearly this time now that we have been around this block a few times.

Saturday, October 26, 2019

Successful test flight, good performance

Today I flew the latest Airball hardware on N291DR, and it worked beautifully!!! In particular, as I was calibrating the airspeeds, I noted that I was getting VFE = 70 kias at exactly the same point as the airplane's built-in airspeed indicator. Stall was predictable, yaw was consistent with the inclinometer, there was no "lag", and overall things were peachy!

Unfortunately we are using a commodity LCD panel which is not as bright as some others we've tried, so I can't show you any video! It washed out completely! Maybe I'll share a video of me flying with it just for fun though.

Here are some photos of the installation.

Saturday, October 19, 2019

New "maker" display is complete

Today I put together the first complete prototype of the "maker" style display -- one which uses commodity parts. There is a small resistor network for the encoder knob, which I made on a piece of breadboard -- that can be a tiny custom PCB at some point. Otherwise, this is built around a standard Raspberry Pi and a 4.3" HDMI LCD panel that's inexpensive and available everywhere. The result looks like this:

We still have a few software improvements / bugs before we get a test flight, but in the meantime, check out the assembly pictures!

Wednesday, October 9, 2019

New probe has 12h battery life as previous

Just confirmed the new probe has a 12 hour battery life, comparable to our previous design. This is not surprising, given that it's just a recasting of the same hardware, but it's still good to know. Here is the probe sitting on my desk at work today. The LED blinks on or off per data cycle, so it is blinking at 10 Hz and the data is going out at 20 Hz:

Friday, October 4, 2019

New probe design

It's been a while since we posted, and it's not for lack of activity.

We have switched to using Honeywell pressure sensors, since they are (as best we can tell) more reliable. And since they are not as easily available in different types, we decided to use a Bosch BMP388 barometer instead of a high-zoot ported pressure sensor. This meant we were up for a big board rev.

In the meantime, we re-evaluated and decided we could get by with a less custom sensor board, using a few "breakout board" components to simplify our buildup for prototyping.

The result is our "maker style" probe, which we just got together:

Notice the following:

* Compute module is a SparkFun Pro Micro 3.3V.

* Power is provided by a SparkFun Battery Babysitter.

* Barometric sensor is an Adafruit BMP388 breakout board with a 3D printed "cap" to provide a port for redirecting the static probe pressure to the sensor.

* The static probe is now attached via a 3D printed pylon to avoid having to bend tubing, and it is made of a piece of regular hobby store brass tubing.

* Various changes have been made to the mechanical parts to make them easier to assemble.

We will be trying this probe out in flight and also, as we build more copies, showing more details of how it's put together. We're still trying to iron out some of the bugs.

Stay tuned!!!