Air cooled VM still

[nwvapors]

I am building a VM still. 2" packed column 48" long, 1" take off at the head and I am interested in an air cooled reflux condenser.
I have seen finned copper tubes in plans and pictures but how do you go about calculating the size and number of these finned tubes
you will need? What angle do you place them at? My boiler is a converted 1/4 barrel keg modified to work as a double boiler, heat
source is a 2400w hot plate. Any info would be greatly appreciated.