the rock drilling apparatus includes main power supply means for supplying power for the rock drilling process which includes at least the sub processes of percussion and or rotation and flushing the method comprising the steps of u2014 adjusting the flush power at least partly as a function of hole depth and controlling at least the percussion power and or rotational power and the flush power such that the total power consumption of each sub process is controlled application_number US 57808104 A description fig1 depicts an exemplary rock drilling apparatus according to the present invention in the figure is shown a rock drilling apparatus 1 in this exemplary a surface drill rig the drill rig 1 is shown in use drilling a hole 2 starting from a ground level at present having reached a depth u03b1 and destined to result in a hole of depth u03b2 for example 30 meters the finished hole being indicated by interrupted lines the shown relation of drill rig height hole depth is not intended to be exact the total height u03b3 of the drill might for example be 10 meters the drill rig 1 is provided with a top hammer 11 mounted via a rock drill cradle 13 on a feed 5 the feed 5 is attached to a boom 15 via a feed holder 12 the top hammer 11 provides percussive action to a drill tool 3 with one or more drill bits 4 via a drill rod 6 supported by a rod support 14 the top hammer 11 is power supplied from a hydraulic pump 10 driven by a diesel engine 9 via a conduit attached.