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2:40 pm
January 25, 2010
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brmj
| | Rochester, New York, United States | |
| Member | posts 402 | |
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While googleing for information to help the USOFS improvement project, I came across something called OpenRocket. It is free (in both senses) software for designing model rockets and simulating launches. It is obviously intended for small, solid fueled rockets, but it is flexible enough that we might just be able to make it work as is, if we so choose. If we were to just import the materials data for aluminum and so on and add in some code to deal with hybrid rocket engines and provide improved supersonic drag calculations, it might be excellent for our needs.
What does everyone think?
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Main work groups: Propulsion (booster), Spacecraft Engineering, Computer Systems, Navigation and Guidance (software)
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6:41 pm
February 9, 2010
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Luke Maurits
| | Adelaide, Australia | |
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Sorry for taking so very long to comment on this.
Good find! If nothing else, it's incredibly useful that this software also comes with a Master's thesis explaining exactly how the simulation works, which should be a huge source of helpful information on how to compute things like stability. I'll definitely give certain sections of that thesis a close read.
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Main CLLARE workgroups: Mission Planning, Navigation and Guidance. I do maths, physics, C, Python and Java.
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10:04 am
June 8, 2010
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sampo
| | Espoo, Finland | |
| Member | posts 9 | |
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Hi,
I happened across this thread while googling around. I'd be thrilled if someone could help improve the supersonic simulation methods in OpenRocket. Currently they give reasonable results up to around Mach 1.5, but the methods are very crude. I tried to find some better methods for example for the body and fin effects, but couldn't find anything simple that could reasonably be extended to fit the components in OpenRocket. Since the emphasis in the thesis was on small rockets I didn't want to spend too much time on the issue.
I'd gladly help along in the implementation. The computational methods are separated from the simulation, so it's a straightforward matter of getting in airspeed etc as input and computing the aerodynamic coefficients. The code is overall quite decoupled, so you can easily substitute for example custom atmospheric models etc.
What kind of customization are you considering for the hybrid rocket engines? I'm currently rewriting the motor handling code to be more flexible, in order to support for example water rockets (which requires dynamic thrust computation). It should be flexible enough to support almost any kind of motors.
OpenRocket also contains extension mechanisms that allow for example custom code to run and modify the rocket during simulation.
Cheers, Sampo
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1:37 pm
June 8, 2010
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sampo
| | Espoo, Finland | |
| Member | posts 9 | |
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Hi,
Having examined the current USOFS software and few threads from the forum I don't see why OpenRocket couldn't fulfill all the current requirements. It has in place a framework that combines all the different simulation components (aerodynamics, mass computation, wind, thrust, gravity, etc) and an RK4 simulation engine. Several of the components require some finetuning to be able to reliably simulate 100K flights, but the same applies to USOFS. OR also already has a GUI for rocket design and simulation.
My goal with OpenRocket is to have it simple enough for normal model rocketry work, but robust enough for demanding flights such as these. I don't see these goals contradicting – it's nothing away from a model rocketeer if OR can simulate 100K flights as well as 100m flights. I also already got some ideas from reading these threads on how to make the external listener interface to be even more flexible and allow customization from within the GUI.
Some parts of OpenRocket that would likely need the most work are extending the atmospheric and wind model to 100K and supersonic simulation. In later stages of development also a spherical coordinate simulation engine may be desired that takes the curvature of the Earth into account.
(I hope I'm not stepping on any toes here…)
Cheers, Sampo
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9:24 pm
June 8, 2010
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Luke Maurits
| | Adelaide, Australia | |
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| posts 1483 | |
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Hi Sampo,
Definitely not stepping on any toes! I say this as the person who wrote USOFS, which is definitely very rudimentary compared to OpenRocket. If I'd known about OpenRocket from the start I probably would not have bothered writing USOFS! Unless anybody else can point out any reasons why an extended version of OR would not be appropriate for simulating OHKLA flights, I have no real problem with us focusing on that instead. I would be willing to help with extensions on OR to the extent that I can – I have programmed in Java before (I'm a little rusty these days, but that will go away quickly), however I don't know an awful lot about aerodynamics (just how to use coefficients of drag and lift, really, and I am fairly sure those simple equations break down for supersonic flows)j. I do have an applied mathematics degree, though, so I will be able to learn relatively quickly. I do remember having a quick look at your Masters thesis when this thread first started and it seemed really interesting and accessible enough: I just wish I had the time to read it cover to cover in detail! Could you elaborate a little bit on what sorts of extensions would be required? Perhaps if I could read more specifically on those topics I could get sufficiently up to speed to help in a short amount of time.
Thanks for stopping by!
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Main CLLARE workgroups: Mission Planning, Navigation and Guidance. I do maths, physics, C, Python and Java.
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