About a year and a half ago, I came across the little ecosystem revolving around the Turnigy/FlySky 9x radio sold for about $50 by Hobbyking. The context is rather silly but interesting: I had found and bought the little E-flite Sbach UMX bind-and-fly airplane I had fallen in love with, and being a Futaba user (still on 35MHz) I needed a radio for it. Of course, my Sbach was to receive the usual mandatory upgrades, i.e. an FPV equipment set with a panning camera (see the related posts for more info). But there came the problem: Those things have built-in Spektrum receivers. To control camera pan, the common solution is to use a headtracker and/or a knob on the radio. A quck search revealed that Spektrum radios are not headtracker friendly, and at that time the first radio in their lineup that featured a rotary knob was the $400 DX8.
I was certainly not going to spend $400 to control a $120 model when I was already equipped with other gear for my other models, so as a certified tinkerer I started looking for alternatives. It turns out that the 9x radio had quite an active community around it, who had developed several different alternative open source firmwares as replacements for the original rather poor Chinese "interpretation" of the Futaba 9C's firmware. One of the features of the open source firmwares is that it can talk the serial protocol needed by RF modules taken out of genuine Spektrum radios. I apparently wasn't alone with my requirements. Besides that the hardware had what I needed (3 rotary knobs), and the firmware could happily take a headtracker input. I thus ordered a 9x and what's required to reflash it, bought a cheap 2nd-hand Spektrum DX4e to take the module out, and added one of the other popular 9x addons which is the telemetry-capable FrSky DJT RF module and matching receivers.
I set up to installing the programmer in the 9x, wired the DX4e's module in the 9x's original module case and did the telemetry mod to go along with the FrSky module. The idea way to have swappable modules without any dangling wires to be able to both fly my Sbach and experiment with the FrSky gear. There seemed to be 2 main alternative firmwares around, er9x which was the most popular one, and open9x which is a fork of er9x but was a bit too new to be known yet. I started off with er9x for a week, and then tried open9x as a comparison - never to turn back. In my opinion open9x was the "polished" version of er9x, eliminating most of the "hacks" and inconsistencies that were in er9x to turn them into cleanly implemented features.
I got on well with the firmware, had no trouble to do exactly what I wanted, and loved the FrSky link with its telemetry feature enough to notice that after 4 months I hadn't touched my Futaba T14MZ once, all my models got upgraded with FrSky telemetry receivers and reprogrammed on the 9x, usually in a 3rd of the time it had taken me on the Futaba. In the meantime I started becoming quite active on the 9xforums board where everything around that radio was happening, and making a few suggestions to Bertrand Songis, the main open9x developer. Those suggestions were usually well received, when not implemented in the following day or even hour. This was a start of a closer collaboration and great interest, the fact that it was so well done yet showed lots of potential for improvement pushing for more involvement.
The Futaba radio was really being forgotten in a closet and ended being put up for sale as the 9x felt superior to me in every way but one, which is the "quality" of the $50 hardware. So when FrSky announced they were starting to work on a full-fledged radio that was to be open to 3rd-party development, this felt like we had the opportunity to participate in something that could be exaclty what we needed: open9x was an excellent software, but unfortunately limited by a very low end platform with a steep entry curve as the 9x is a $50 radio, and loading open9x onto it required hardware modifications that were not really within the compentences of the average modeler.
So soon enough the open9x (renamed to openTx due to the new multi-platform capability) team started working on a port to what would become the Taranis, starting with adapting the simulator to the radio's screen dimensions to help redesigning the UI around it. Beta schematics of the radio followed with work starting on the hardware drivers, and design flaws / desirable features being relayed to FrSky, and usually accepted.
So now nearly a year later, an affordable, decent hardware quality radio with extremely powerful open-source software is being put on the market, and will certainly revolutionise the R/C world in its own way by breaking all the marketing-driven limitations common among major manufacturers!