It'd be nice to use the Skydemon fuel feature in the aircraft profile but I just can't get it to give a sensible number, obviously because the data I'm feeding it is not accurate.

I fly an Xair 582 and work on 15ltrs per hour using - flight time+30 minutes taxi/messing about time per flight+60 minutes contingency. This average calculation serves me well but I can find no way to setup Skydemon to do a similar "Simplified" fuel model in the aircraft profile. 

Any ideas ? TBH I work out my fuel manually, it's not hard but would be nice when planning to have Skydemon do it for me.