George

For a decade and more I used four Sanyo N110 NiCd cells to power the receiver and servos. The energy used for an F5B flight I measured at 25mAhr for a two servo wing (Surprise 11) and 40 mAhr for a four servo wing (Avionik B06). So the 110 mAhr was plenty. I tried equivalent weight (30gms) NiMH with bad results. The voltage fell to dangerous levels at high (2.5A) currents, especially in cold conditions.

New NiCds  became difficult to get, then in addition I had space problems in the B06. So I decided to jump to LiPo cells with a regulator. 2S LiPo packs intended for indoor flight can supply 5A with ease, and weigh 20gms. The only problem is that they need a regulator to reduce the voltage from 8.4 V to something acceptable to the radio. Switching regulators are on offer to do this, but I feared them as in the Avionik they will be hard up against the receiver and interference would be a problem. Linear regulators  are available and used by some, eg Joe Mouris (Flight power) and David Hines (Thunder Tiger). But they are big and heavy and I could not see how to fit them into the Avionik. So I decided to build my own.

Commercial linear regulators are big because the designers build them for continuous operation. For F5B this is not necessary. The currents can indeed be 2.5A or more, but the total energy throughput is only max 50mAhrs in 15 minutes, an average of 200mA, generating very little heat. So  a small PC board is all that is required. The one I used is 38mm x 19mm as shown below.

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.