On small RC models, often the simplest method for mounting a propeller on the motor is to use a prop saver.  This simple device saves the need to fit a propeller to a prop adapter, and also helps to minimize the damage from prop strikes on belly-landings and nose-overs.   

For those who are new to the hobby and who may be unfamiliar with prop savers, we have created a short video to help illustrate the method of attaching a propeller to a prop saver and installing the prop saver on a motor shaft.