QuickStart — RocketCEA v1.1.18 documentation

# QuickStart

Note

Python 3.8 on Windows has been problematic and is not fully supported.

Python 3.8 64 bit on Windows has been made to work by using the new os.add_dll_directory command to locate MinGW DLL libraries, however, 32 bit python 3.8 is not yet supported.

## Install Numpy & Matplotlib

Because RocketCEA depends on f2py to compile the FORTRAN NASA CEA code and f2py is part of numpy , numpy will need to be installed.

RocketCEA also makes use of the matplotlib package for creating plots.

To install numpy and matplotlib, give the commands:

    pip install numpy
    pip install matplotlib

    OR perhaps...

    pip install --upgrade numpy
    pip install --upgrade matplotlib

Some Linux systems may require:

    sudo pip install numpy
    sudo pip install matplotlib

## Install Compiler

Using f2py to compile FORTRAN requires a FORTRAN compiler. I recommend using gfortran on all platforms so that there are no FORTRAN incompatibilities between platforms.

Each operating system has its own approach to install gfortran

Click: Install gfortran to see install instructions for a few platforms that I have tested.

Important

Windows users MUST put MinGW into environment PATH variable. (see: Windows PATH)

C:MinGWmingw64bin OR C:MinGWmingw32bin

and

C:MinGWmingw64lib OR C:MinGWmingw32lib

## Install RocketCEA

After the above installs have been accomplished, the easiest way to install RocketCEA is:

    pip install rocketcea

        OR on Linux
    sudo pip install rocketcea
        OR perhaps
    pip install --user rocketcea

Try a quick test of the install by pasting the following into a command terminal:

    python -c "from rocketcea.cea_obj import CEA_Obj; C=CEA_Obj(oxName='LOX', fuelName='LH2'); print(C.get_Isp())"

    should result in:
    374.30361765576265

## Getting Help

After installing with `pip`, there should be a launch command line program called rocketcea or, on Windows, rocketcea.exe.

From a terminal or command prompt window simply type:

    rocketcea

Your browser will launch with these RocketCEA help pages.

## Running RocketCEA

Any use of RocketCEA begins with an import statement and an instance of CEA_obj:

    from rocketcea.cea_obj import CEA_Obj
    C = CEA_Obj( oxName='LOX', fuelName='LH2')

In the above example, LOX and LH2 are called out, but any propellants on the Propellants page can be used.

There are a large number of examples included in this document

For instance, look at LOX/LH2 Performance on the Standard Examples page.

To run an example, highlight the source code with your mouse, right click the highlighted code and select Copy. Paste that code into your text editor and save it to a python file.(for example D:\rocketcea\example_1.py).

Example files can be run with the command:

    python example1.py

Or, in many text editors hitting the F5 key will execute the code.

Note

RocketCEA is compiled with the mingw and mingw-w64 gfortran compilers using default f2py options giving a “shared” *.pyd file that requires mingw libraries at run time.

If you see the error: `Import Error: DLL load failed: The specified module could not be found` You may need to install the MinGW Compiler Suite and perhaps even recompile RocketCEA in order for RocketCEA to work (see below)

On Windows, make sure the environment PATH variable is set properly (see: Windows PATH)

## Test The Install

Paste the following code into your text editor and save it to your test folder as basic_cea.py (for example, D:\rocketcea\basic_cea.py):

    from rocketcea.cea_obj import CEA_Obj
    C = CEA_Obj( oxName='LOX', fuelName='LH2')
    for mr in range(2,9):
        print(mr, C.get_Isp(Pc=100.0, MR=mr, eps=40.0) )

At the command prompt, give the command:

    python basic_cea.py

If you see the following output:

    (2, 424.3597085736007)
    (3, 445.44434236555196)
    (4, 453.13271951921837)
    (5, 453.240429182719)
    (6, 448.190232998362)
    (7, 438.74340042907266)
    (8, 424.6998266323161)

Great… you are good to go.

If not, see the information below.

## Google Colaboratory

If you are having trouble installing RocketCEA on your system, RocketCEA can be run on Google Colaboratory (either python3 or python2).

Colaboratory is a free Jupyter notebook environment that requires no setup and runs entirely in the cloud.

After creating a Colaboratory notebook, install RocketCEA.:

    !pip install RocketCEA

If Needed, install libgfortran3:

    !apt-get install libgfortran3

Create a python script to run RocketCEA:

    %%file chk_cea.py
    from rocketcea.cea_obj import CEA_Obj
    C = CEA_Obj( oxName='LOX', fuelName='LH2')
    for mr in range(2,9):
        print(mr, C.get_Isp(Pc=100.0, MR=mr, eps=40.0) )

And then run the file:

    !python chk_cea.py

Colab plots work with RocketCEA as well.