Looking at performance prediction of small coaxial rotorcraft, it was found that there are no fast methods available for designers. This research was aimed at using a blade element method in combination with the momentum theory to quickly predict the performance at small coaxial rotorcraft. These methods are successfully applied in larger rotorcraft. It will therefore be of interest to see how these methods perform when the aerodynamics changes due to scaling. Especially the Reynolds number effects are expected to influence and potentially limit the application of the modelling methods. The new developed model was tested on the full-scale Kamov 32 helicopter as well as two small Unmanned Aerial Vehicles. These are the commercial available Walkera Lama and the Guardian Angle, which was developed by undergraduate students during a design synthesis exercise. The results show a successful implementation of the calculation methods, with some interesting insight in the limits imposed by them.