About RocFlight Software

RocFlight was developed by Zach Owens who began working on the project in the year 2000 while he was an undergraduate at the University of Virginia. Initial development of the program was funded by NASA's Virginia Space Grant Consortium and the software is currently being used as an instructional tool in the Aerospace Engineering curriculum at the University of Virginia.

As a means of releasing the program to the rocketry/educational community, Mr. Owens decided to form RocFlight Software Company. RocFlight Software Company is an Internet business specializing in the distribution of RocFlight trajectory software. As of March 9, 2008 an unlocked version of RocFlight 3.1 became available as a free download!

Mr. Owens has previously held positions at NASA's Glenn Research Center and Marshall Space Flight Center. He received his B.S. in Aerospace Engineering from the Univeristy of Virginia along with an M.S. and Ph.D. in Aeronautics & Astronautics from Stanford University.

Program Features:

Two dimensional trajectory simulation
Easy to use graphical interface
Expandable database for rockets, motors, aerodynamic data and case studies
Comprehensive trajectory data log produced for each simulated flight
Graphing utility allows up to nine variables to be plotted simultaneously
Optimal weight calculation tool
Unlimited number of stages and motor clusters can be simulated
Experimental rocket hobbyists can easily define their own custom motors
Simulation can incorporate detailed aerodynamic and thrust history data files
Toggle between English and Metric units
Case studies can saved or printed directly
Comprehensive and searchable help file

Two dimensional trajectory simulation

RocFlight simulates the motion of a rocket vehicle within a plane. This allows users the flexibility to investigate the consequences of a non-vertical launch, and this knowledge can be the difference between recovering your big project, or crashing it into the ground. When picking delay times, either for your motors or your electronics, it is extremely useful to know the projected state of the rocket at the point the ejection charge is fired. With RocFlight you can easily investigate these different scenarios and ensure that even if your rocket does come off the pad at a 15-degree angle, you will have selected a delay time that produces a safe recovery.

Easy to use graphical interface

The RocFlight main screen has been organized into two main sections; one for input data, and one for output data. These two sections are called Simulation Input and Simulation Output respectively. The left section of the form allows users to input data defining the rocket vehicle configuration, motor, aerodynamic performance, and the initial conditions for the start of the simulation. The right section of the form provides the interface to the output data. The output data is organized into three different sections; (1) an overall trajectory summary, (2) a trajectory plotting tool, and (3) a trajectory data file containing a detailed time history of the simulation results. There is also a fourth component of the output data section of the main screen which allows users to compute a rocket vehicle’s optimal mass using the data prescribed in the Simulation Input section of the main screen. Collectively, these components make up the RocFlight interface.

Expandable database for rockets, motors, aerodynamic data and case studies

RocFlight allows users to create and modify files in four separate databases; one for rocket vehicles, one for motors, one for aerodynamic data, and one for case studies. Once a file has been saved to the database, users can quickly mix and match different combinations of rockets, motors, and aerodynamic data in order to investigate the effect on the simulation results. All of these files can be both created from scratch and edited within the RocFlight Database Editor.

This File Support section of this web site serves as an update center for these database files. As RocFlight users begin to define rocket files and aerodynamic data files they are encouraged to submit them to RocFlight.com so that they can be available to all RocFlight users. Also available on this section of the website is a spreadsheet tool that will allow users to convert their current wRASP motor and rocket vehicle files into the format used by RocFlight.

The rocket vehicle database contains geometry, weight, and drag coefficient data for a given rocket. The database supplied with RocFlight currently contains 963 rocket vehicle files. These files have been converted to the native RocFlight format based on data available in the wRASP rocket kit database. Please note that an arbitrary drag coefficient of .75 has been applied to all the files in this database. Users are encouraged to submit these data files for common kits as they create them. This can also be done through the File Support section of this web site.

The motor database currently contains 412 commercially available motors. The format of these motor files is the same as that used by Roger Aeroscience's Alt4 program. Unlike most motor files, this format allows the simulation to take into account pressure thrust, which is variable as the rocket travels through the atmosphere. The RocFlight motor data files are a combination of the Alt4 and wRASP motor databases.

Drag performance data refers to a file that contains a series of drag coefficient vs. Mach number pairs. These files allow the simulation to vary a rocket's drag behavior as a function of Mach number. While these files are most typically generated through the use of a wind tunnel, simulated data can be acquired via the use of aerodynamic prediction software such as AeroDRAG.

Case files can be created for each 'case' run through the simulator These files serve as an easy way to document different scenarios. Each case files can be accessed through the RocFlight Database Editor, where it can be printed and/or modified. These files also contain a section for the recording of actual flight data. In this way they also function as an easy way to document your various flights. More information on case files is available in the case file section below.

Comprehensive trajectory data log produced for each simulated flight

Each time a given case is run through the simulation a sampling of the most critical data is stored in an array that can be viewed by the user. Within RocFlight this is called the Trajectory Data File. This data file contains key data sampled every tenth iteration during the flight routine. Access to this file allows program users the flexibility to see exactly how their rocket is behaving throughout the entire flight. Users can also simply Copy and Paste this data into other applications, such as Excel, in order to plot the data in a more customizable format.

Graphing utility allows up to nine variables to be plotted simultaneously

Through the use of scaling factors, up to nine variables can be plotted versus time, all on the same graph. This allows for easy visualization of how one variable is reacting to another. If an alternative plot is desired then data from the Trajectory Data File can be copied into another graphing application such as Excel.

Optimal weight calculation tool

The Optimal Weight tool allows users to iterate through a number of vehicle weights in order to see the effect on the rocket's key output parameters. This tool can be used to determine the vehicle weight which produces the maximum altitude, range, or just to explore the sensitivity of performance to weight.

The feature is particularly useful during the design phase of a new rocket project. Once an optimal weight has been identified for a given configuration, precautions can be taken to select the proper materials and payload to satisfy this design criteria. You may be surprised to find that in some cases you will need to add weight to your designs in order to achieve maximum altitude.

Unlimited number of stages and motor clusters can be simulated

RocFlight allows its users to specify an initial altitude, range, velocity and angle. In this way an infinite number of stages can be accommodated simply by running each of the stages of your rocket through its own simulation. This is accomplished simply by using the results of previous stages to specify the initial conditions for upper stages.

RocFlight allows its users the ability to easily define custom motors. Thus to simulate a rocket which has a single J300 and two G80s simply combine the respective motor files into one. You'll only have to do this one time since you can save this cluster combination motor file for future use.

Experimental rocket hobbyists can easily define their own custom motors

The main interface to RocFlight allows for up to five thrust vs. time pairs to be entered. By using this feature custom motors can be defined without hassle. If more thrust time pairs are desired than this can be accomplished through the use of the Database Editor. Up to 1,000 thrust vs. time pairs can be entered in this manner.

The RocFlight simulation routine will account for the changing pressure thrust acting on a rocket ascending through the atmosphere, provided a nozzle exit diameter and design exit pressure are entered. For larger rockets, flying to higher altitudes, accounting for pressure thrust can make a substantial difference in the total impulse of the motor, and hence have an appreciable effect on the simulation results.

The format of the motor data files also provides an easy way for experimental rocket hobbyists to book keep their latest motor design. Entry fields are provided for information such as mass fraction, Isp, grain type, etc...

Simulation can incorporate detailed aerodynamic and thrust history data files

RocFlight allows for motor data files containing up to 1,000 thrust vs. time pairs, and aerodynamic data files containing up to 100 Cd vs. Mach number pairs to be used within the flight routine. This is ideal for projects where you may have measured detailed thrust histories and possibly even wind tunnel data.

When creating large data files you will need to replicate the exact format used by RocFlight for the type of data file you are creating. If you have thrust history data or aerodynamic data already in a spreadsheet program it is easiest to just append the necessary text labels to the data within the spreadsheet program and then export the file to the appropriate RocFlight folder in text format. You will also need to append the appropriate file extension when performing this operation.

Toggle between English and Metric units

RocFlight can operate in either English or Metric units. Switching between the two units systems can be done with a click of a button. When the units are switched all current input and output data are automatically refreshed in the new system of units.

All data files used by RocFlight, with the exception of case files, are always stored in English units. However, when importing these files from the RocFlight database, they will be converted to the unit system currently in use. Case files are saved in whichever units system is in use at the time the case file is created.

Case studies can saved or printed directly

After a rocket configuration has been simulated, a case file can be generated which stores all the input and output data. These case files can be saved for later access using the database editor, or sent directly to the printer with the click of a button. When case files are printed directly the user will be prompted to enter a name for the case file, which will be appended to the printed output.

Case files also contain data entry fields for actual flight data. This has been included so that a case file can be printed out, taken to the launch site and then used a journal entry tablet for the actual flight. This provides an easy way to keep track of all your flights and will aid in comparing simulations to your actual flight data. This type of comparison is most easily facilitated when flying a rocket with a flight logging device such as an accelerometer. RocFlight Software Company would be very interested in receiving this type of comparison data back from its users and would consider including data such as this on the website.

Comprehensive and searchable help file

Reading the RocFlight help files is a sufficient means to learn how to use the software. These files contain information about the computational model used by RocFlight, tutorials on how to enter data and use the various RocFlight features, tips on trouble shooting, and a FAQ section. To obtain the latest version of the help files see the File Support section of this website.