Hi Richard,
Looking good, though perhaps a bit on the big side for my own installation inside a flex wing pod
. WRT the 'red box' there are lots of converters out there to allow running 12 volt equipment in 24 volt vehicles (e.g. most lorries), so you should be able to incorporate a suitable converter if you need to run the red box (and 12 volt fan) from 24 volts. Good news on the fan. I always reckoned that as long as there was sufficient 'free area' to prevent internal pressurisation that would be the case. Nice to see it proved. I would guess a 12 volt fan would probably run smoother and hence quieter and probably a bit heavier construction, so possibly longer lasting.
I like the idea of a manual audio volume control. A colleague has just built a mixer to merge his radio and PAW input to his intercom, which also provides this function. Much easier / quicker than trying to adjust the PAW audio from the configure screen in flight. I know several others have fitted mixers previously and although I don't need it to match levels, I may go down this route just to provide rapid and convenient audio adjustment.
FYI, I have been using USB stick for some time now to update PAW with the FLARM Integration engineering updates and it works great - extremely fast - and also allows super fast downloading of PAW track logs. Much faster and simpler than the old methods, though there is one minor issue when you put your 'stick' back into a windows PC as Windows doesn't recognise the PAW.pgp 'update' file and mistakenly reports the stick as 'faulty'. Simply ignore this 'warning' and all is fine.
IIRC the 'red box'
can be updated via the data cable, but not sure this could be achieved from PAW without seriously upsetting F*ARM's legal department though!
Keep up the good work
Regards
Peter