The PB51 was designed by Tommy Borsboom. The design was meant as a third-year internship program. The name is in honour of his father, PB.
The PB features a propellant combination of a sugar and an oxidiser. The grain configuration is in a bates variant. The motor case made of aluminium. The nozzle is made out of graphite part in a bell shape and an aluminium part in conical shape. The engine is fully separable and thus, easy for maintenance.
The engine produces a mighty 1008 Newtons of maximum thrust. It has a total impulse of 3350 Ns. This allows the team to shoot rockets up to 2.5 kilometres. The engine has a maximum acceleration of 12 g's. The maximum operating chamber pressure is 45.1 bar and the maximum chamber pressure is 110 bar.