Friday, July 13, 2018

Test flight by Tom Jones (KSNS)

As noted earlier, Tom Jones is a friend of mine who flies a Rans S-6S out of KSNS. He recently did a data gathering flight with the latest Airball system. Like his friend Jim Shumaker, he got the thing running with no help from me -- apart from a minor confusion about the multiple USB ports that we have on the prototype display!

This is Tom's airplane at KSNS:

And this is the awesome video he made, which apart from its documentary qualities also counts as bona fide Airball advertising:

Here are his remarks, verbatim:

Date: 7-1-18

Aircraft: RANS S-6S, standard wing

Pilot: Tom Jones

Elevation of Flight: 100’ to 5,700’ MGL

Temperature: 71F to 85F

Weather: Warm, Inversion Layer, Light Winds (<5 mph), Smooth Air Above 2,000'
Sensor Installation: Right Wing, Main Strut, Mounted Mid-Span between Jury Strut & Main Strut/Wing Interface

Display Installation: Instrument Panel RAM Mount

Evaluation Aircraft had an Inclinometer mounted to the instrument panel and has instrument panel mounted Blue Mountain Avionics Gen 4 EFIS. This EFIS features an electronic Inclinometer function. In general the two instruments track well. However in high angles of attack and steep turns the Inclinometer ball tends to experience a left bias, up to 1/2 of a ball diameter from the EFIS.


Installation of Sensor: The custom mount fabricated for the RANS S-6S worked well with no observed movement.

Installation Display: No issues mounting the display.

Operation of Sensor: No issues in operating

Operation of Display: Issue connecting external battery to Display. Initially tried connecting standard USB connector to Display. With Ihab's clarification - mini USB connects to display and standard USB connects to external battery. No other issues experienced. Boot time was under 1 minute. Not sure of purpose of the 4 standard USB connectors?

WiFi Connection: Self connecting no issues. No WiFi issues in using this device with my Stratus 2S. Display typically showed a signal strength from 50% to Full; on average 75%.

Display: In general the display was clear, about the same brightness as the Blue Mountain EFIS. With my sunglasses (unpolarized) on it was difficult to see the red reference line. The blue ball was easy to see. Note: Skies were clear, the sun was at the zenith and the aircraft had a clear sky light. It was difficult to record video with the Cannon video camera, due to glare.

The Air Ball was sensitive to change in comparison to the Inclinometer and EFIS. The ball was bouncing (jitter) around which I found to be somewhat irritating.

In general cruise (80 to 120 mph) the beta drift was minimal. At higher angles of attack the ball drifted to the left.

On steep turns to the left - Air Ball tracked well w/ the Inclinometer.

On steep turns to the right - Air Ball tracked well w/ the EFIS.

On landing the ball drifted to the edge or just off the display.

On the return leg I had to adjust the beta bias. I’m not sure why - if it was mechanical related or due to temperature drift or something else?

Otherwise the Air Ball performed flawlessly. As alpha was reduced the ball would move to the top of the display and visa versa. As the aircraft was yawed to the left the ball would move to the left and visa versa. As air speed was increased the ball would get larger and visa versa.

1. On case of display identify mini USB as Power In.

2. Recommend adding a user controlled damping function - user adjustable sampling / averaging of data points or possibly having a user adjustable sampling rate. This should help reduce ball jitter.

3. Consider changing the color of the ball as a function of airspeed, i.e. White, Green, Yellow, Red.

4. In the center of the ball you might consider displaying airspeed.
Once again I am grateful to Tom for this awesome and well-organized report. A few quick notes:

USB port clarity: Our bad! Prototype hackery hardware for the win!

Jitter: Totally agree with Tom that we need filtering and that it should be user adjustable. We have shied away from filtering so far because we don't want to mask away the "instant wind-sock" aspect of the instrument, but now's the time to smooth out the jitter.

Brightness: Jeremy's new displays will fix that!

Beta bias: We know about that and we're working to add the accelerometer. All told, I suspect something may have bumped the probe out of alignment while the plane was sitting on the ground between Tom's outbound and return flights, but if that's not the case and there was some discrepancy, we'll find it soon enough!

User interface suggestions: Thank you. We have thoughts about adding V speed tick marks around the size of the ball, as part of a more comprehensive Airball-based VFR instrument (see below), so we will take all these thoughts together and see where they lead us.

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