Limiter

The CC125 (or CC180) is perhaps our most common controller. It is neither opto-coupled like the Schulze or Hacker Master 195, nor directly connected like the Kontronik FAI and most cheaper BEC controllers. Instead it has two filter components, said to be inductors, in the BEC power lines, most notably the ground (black() line. I measure the resistance of this to be 0.1 ohm, but Steve Neu has reported seeing much higher resistance.

Most sensors, eg voltage sensor for the limiter, rpm sensor on the Unilog, require a solid ground connection. In the case of opto-coupled controllers this is achieved by connecting the blue wire (Neu) or brownie-black wire (Unilog) to some point  on the power negative which becomes the ground reference. In the case of the Kontronik and most other BEC controllers this connection is made within the controller and the Blue/black connection is not necessary, in fact not desirable as two ground connections can lead to ground loops.

For the CC125 the situation is more complex. It normally works with either configuration but Neu now recommend connecting the blue wire (black on the Unilog). Without it voltages developed across the inductor can interfere with the sensor readings. But with it voltages across the inductor, or developed across the wiring ,can damage the inductor or even cause the controller to mal-function.

An alternative approach, avoiding ground loops and simplifying the installation, is shown below. This involves removing the inductor from the circuit, thus making the CC125 the same as the Kontronik or normal BEC controllers. This removes the filtering effect of course, making an optocoupler to the receiver even more of a necessity. Connecting the blue/black wire also removes the filtering. Removing the inductor requires uncovering the controller and some fine soldering so can only be undertaken by those with electronic experience and capability.

The UniF5B program enables flight data to be read from a Unilog and displayed in a form convenient for F5B. Using the cursor and variable time scales all Unilog data can be examined, plus additional calculated data on motor time and watt.minutes over different parts of the flight. The data can be stored in a file and retrieved later. An on-line display panel allows the Unilog to be used instead of a voltmeter or clamp ammeter. A third panel allows the Unilog to be set up, with a quick setup for F5B. The program is available on Windows and Linux.

       Windows version

The Windows version uses .net 3.5 which is downloaded free and automatically from Microsoft when the program is installed. It is available on http://www.f5b.co.uk/uploads/UniF5B-5KW-19Apr2010.zig for Internet Explorer and http://www.f5b.co.uk/uploads/UniF5B-5KW-19Apr2010.zip for others such as Firefox.  Download and unzip the file. Then change the filename setup.aha to setup.exe. Connect to the internet then click on setup.exe. If you do not have .net 3.5 on your computer it will be downloaded automatically for you, and then the program installed. I suggest you just close the HTML directory page that the installation opens to let you see what it has done. Start the UniF5B program from the Windows Start Menu.

The latest version from April 2010 has a fix where power over 5KW is correctly calculated.

The introduction of the limiter from 2008 was one of the most profound, interesting and controversial developments for F5B (and F5D). This section goes into more detail. It describes the hardware and software available, installation hints, testing results and operational results as they become available.

A bit of history. The limiter was proposed at the CIAM Technical Committee 5 meeting at the 2006 World Championship in Pitesti. To verify the possibility, and for fun, Mark Haig and George Shering decided to build one. Two different approaches were used. Mark built a simple limiter from scratch, doing all the hardware and software himself. This is shown below and was the first limiter to "limit" on the bench.

George took a different approach. In flight loggers had appeared on the market. So it was decided to modify a BnB DPR-1 logger to add limiting capability. This resulted in the device shown below.

The current capability was more than doubled by adding shunt wires, an input cable from the receiver was added, using a Medusa opto and a Kontronik filter toroid for good measure. The controller connection was taken from the modified white socket. The big problem with this approach was the software. Probably for good commercial reasons BnB would not provide a circuit diagram or the software, so it was necessary to reverse engineer the hardware and completely re-write the software, good fun!

Anyway this was all finished and the unit flown before the March 2007 committee meeting in Lausanne. This limiter retains the logging capability so it was possible to demonstrate the flight on the PC to the committee. They were convinced that the limiter was a viable option and it was adopted in the rules for 2008.