To ensure the Bug hit its target, a mechanical system was devised that would track the aircraft's distance flown. Before takeoff technicians determined the distance to be traveled relative to the air, taking into account wind speed and direction along the flight path. This was used to calculate the total number of engine revolutions needed for the Bug to reach its destination. When a total revolution counter reached this value a cam dropped down which shut off the engine and retracted the bolts attaching the wings, which fell off. The Bug began a ballistic trajectory into the target; the impact detonated the payload of 82 kilograms (180 lb) of explosives.