Sunday, June 12, 2022

Project update: Shipping

We have been shipping units to friends, and hope to report results soon. Meanwhile, enjoy these photos of the Airball units as shipped; a sort of simulated unboxing!

Project update: The mount

Mounting the probe is always the big challenge. The latest round of builds produced this thing, which combines a "vee block" and "tee square". Note the metal hardware to align the probe. A huge amount of work and prototyping went into designing and building this, and it's not even quite done yet.

The design uses AN hardware in important locations, and on the airplane, it looks like this:

I am also now printing the important parts of the mount in 100% infill PETG, and the whole design has been beefed up considerably. This replaces a whole host of RAM mount predecessors -- once my bush pilot friends got a hold of the RAM mount, they laughed at how wiggly it was! The new design is rock solid; if it fails, then your plane has other problems besides Airball. :)

Project update: The display

The display is kind of the root of all evil in this system. We require a pretty beefy processor (not a monster -- just not a tiny microcontroller) to display the necessary (approx.) 20 FPS anti-aliased graphics. We need a bright screen, but given the givens, we don't have one because we have yet to successfully build a new custom system with a sunlight readable LCD module.

Our latest system is this, which uses a Raspberry Pi 3B+ and a Waveshare 3.5 inch LCD:

Project update: The probe

For good or for ill, the heart of our system is our airdata source, i.e., the probe. This is roughly what our latest-model probe looks like:

Notice that the probe parts are made of HP MJF Nylon, and the probe is equipped with an explicit static probe made of silver-soldered brass.

This probe has been shown to provide very consistent airspeeds in a wind tunnel, under varying orientations. Basically, any air data quality problems are now gone. Check out this video:

Another project update

It's been a while since I posted on this blog. I assure you that work on Airball is going strong, but things have shifted a bit.

I am basically at the point where the "technology demonstrator" phase is done, and I need to find a beachhead market and get this thing into people's hands. This may involve a "hobbyist" release made of 3D printed materials that people can make (per the original plan), or it may involve handing this off to a corporation, or ... any of a number of other options.

In order to get this pitch honed, I have been working on putting working prototypes in people's hands. I have at least one STOL / bush flying friend right now who is using this thing regularly, and we are figuring out what the best user interface abstractions can be for his type of flying.

Below is the situation in April 2022, with 4 systems (plus one "off camera") ready to send out. We have since found tweaks and improvement, which I will detail in subsequent blog posts, focusing on the probe; the display; and the mounting.

Saturday, January 29, 2022

Project update

Greetings folks. It's been a while since I posted an update. I've been working heads-down super hard, so this is actually good news. Some random items...

First of all, IAS accuracy is brilliant when I went to a non-porous materials for the entire air path. I verified this by blowing into the probe and comparing a water manometer with the readings. The porous 3D printed material creates enough leakage to create enough of a flow to create enough of a head loss to change the results dramatically. The new probe nose is made out of HP "multi-jet fusion" plastic by and the prototype probe looks like this:

Note the tape because the temperature sensor bits were still in the mail. This is all getting improved.

I have moved to a brass brazed static probe that has a rectangular section to hold it in place securely, rather than the bent tubes that wiggled out of position. This is what it looks like, in progress and completed:

I have moved the probe protocol from TCP to UDP, to improve instant-on reliability. I have also made the Raspberry Pi display the Wi-Fi base station, to off-load complex work from the ESP32 probe. I completed the work on the Web configuration editor.

I updated the climb rate algorithm in the altimeter -- now it attempts to fit a polynomial to the latest N pressure altitude readings, and then reports the slope of that polynomial at the current time. It seems to be a better balance between stability and instant feedback. We'll see how it fares.

I added audio to Airball! I added a micro-framework for audio output, then added two sound "schemes". One is "FlyONSPEED" -- using the work of my friends at The other is "stallfence", which is just basically a simple progressive yaw and stall beeper. I hope to get more user feedback on what people want to see from audio!

I'm in a full-on production run of 5 units, followed by 10 more units. Wish me luck!