Third-Party Compatibility

Preface

OpenRocket is one of the best flight simulation software packages for model rockets, from low to high power. Even so, there are times when structural strength and aerodynamic predictions should be independently verified, such as when very high speeds or velocities are anticipated.

Fin Flutter: Very high speeds and velocities can generate oscillations (rapid back and forth movements) within a component that compromise its structural integrity. The component most susceptible is the fins, a phenomenon common called "fin flutter." At its extreme limit, excessive fin flutter can result in one or more fins being literally ripped off the body tube near the fin root edge, even if the fins are through-the-wall (the fin materially itself is tearing). OpenRocket does not analyze fin flutter, but, if there is such a concern, AeroFinSim performs this type of structural strength analysis.

Mach and Above Mach Flights: During flights that exceed the speed of sound, a change in the drag coefficient of the rocket can significantly affect altitude. Overall, the drag coefficient estimations used by OpenRocket match the experimental results with reasonable accuracy, and the results of actual test flights. But, at higher supersonic speeds the OpenRocket simulation produces less reliable results, producing a too high drag coefficient. If a flight requires a high level of accuracy, RASAero uses flight projection equations equivalent to professional engineering aerodynamic analysis methods.

Third-Party Software

AeroFinSim

Compatibility

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RASAero

Overview

RASAero is a combined aerodynamic analysis and flight simulation software package for model rockets and high power rockets, amateur rockets, and sounding rockets. The RASAero aerodynamic prediction methods are the most accurate available for model, high power, and amateur rockets, and are of equivalent accuracy to professional engineering method aerodynamic analysis codes used for missiles, sounding rockets, and space launch vehicles.

RASAero can also be used for predicting aerodynamic coefficients for use in other flight simulation programs for orbital rockets

Obtaining RASAero

The RASAero application was developed by Charles E. Rogers and David Cooper, and may be obtained from Rogers Aeroscience at:

RASAero.com

Compatibility

RASAero imports the Outer Mold Line (OML) of the rocket from the design file, not any of the internal components, and RASAero does not handle ring fins, or strap-on boosters. Simply put, the OML consists of the outer lines of the rocket including the nose cone, body tubes, and fins, no internal components. However, RASAero also analyses nose cone tip radius, launch shoes, 6 additional fin airfoil section types, and protuberances such as camera shrouds, that OpenRocket does not feature.

OpenRocket does not export a design file directly into the RASAero file format. However, OpenRocket does export a design file into the Rocksim file format, which RASAero directly imports. At this time, to ensure that the process of importing such a file into RASAero is successful, it is recommended that the following steps be followed:

1. Save a copy of the design file using a different name; this file will be stripped of all incompatible components.
2. Delete all components except those necessary to create the Outer Mold Line (OML); leave only the rocket nose cone, body tubes, transitions, launch lugs, and fins (without fin tabs).
3. Save the modified design file.
4. Open the modified design file in OpenRocket 15.03.
5. Save the modified design as a RockSim (.rkt) file.
6. Open RASAero and import the previously saved RockSim (.rkt) design file.

OpenRocket file export compatibility with RASAero, to the extent possible, is expected in the future.

Please Note: Although RASAero is the most accurate aerodynamic analytic for use in model rocketry, it is not without limitations which can prevent the correct importation of a design file. By way of example, RASAero fin shapes are currently limited, and fins featuring a convex angle or other non-standard profile will not import correctly.