I found OpenRocket simple to get start with, due to the very logical design of the interface. You simply choose the components from the upper right and then you set the properties of each component, so the mass of each rocket piece is automatically calculated (and can be manually corrected if needed).
You can set size or even shape properties, choose from the materials list or add your own material, and even determine what paint is used for the component in order to get higher precision on the simulation.
Components are connected to each other as determined by the user and can contain things like the motor of the rocket for example. There are many rocket motors found on the OpenRocket list, but you can always add your own custom motor and its respective properties.
I will choose what most reminds me of Wernher von Braun, so WECO Feuerwerk it is!
There are 16 different components in 3 categories (body and fins, inner elements and mass objects) that you can define, connect with each other and use on your designs. All include common material choices, value override abilities for mass and center of gravity and can be colored differently for better individualization of each component. The designs can also be exported in PDF!
The simulation abilities of OpenRocket allow users to determine with relatively high precision what is going to happen with the rocket they designed. Through this process, we can find out what we can improve, how every change impacts the flight characteristics of our rocket and find out the values of many interesting things like the maximum velocity, max acceleration, the apogee, the flight time and the ground hit velocity.
woGue’s next-get open source rocket will apparently reach 2500 meters before it explodes into hundreds little paws!
More plots can give more details about other things like the drag coefficient, angle of attack and orientation, roll characteristics and many more.
The conditions of the simulation can also be determined by the users. You can set the atmospheric temperature and pressure, the average wind speed and turbulence intensity, the launch rod length, angle and direction and the launch site altitude, longitude and latitude.
What is of particular interest and value, is the ability to determine the stability, drag characteristics and roll dynamics of each component separately and check what the Achilles heel of your design is.
What this tells me is that somehow I managed to design a rocket that has worst drag coefficient than a Fiat Multipla!
So, whether you are a rocket scientist, an amateur rocket designer, some crazy guy with some free time and money to spend, or just curious about rocket flight design and simulation dynamics, OpenRocket will certainly help you discover more about it and maybe even become the motivation to start a crazy physics hobby!