SpaceManMat
Space Nut
- Joined
- Dec 20, 2013
- Messages
- 702
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- 86
Does anyone know why open rocket optimization keeps intermitately returning zero altitudes?
Well it might help if you explain what parameter you were optimizing and how you were doing in.
Bob
Anyway not trying to sound too grumpy would just like reassurance that the "good" values I am getting are actually meaningful.
Well it might help if you explain what parameter you were optimizing and how you were doing in.
Bob
The plot clearly shows altitude vs. electronics mass.
You gave no numerical information on how you conducted your optimizations but the above reply has the information I was going to suggest.I suspect you will find this all over the place when using the optimizer. Reading a bit on the optimization of OR it is pretty complex. To me the error appears to be either the optimizer choosing not to sim some values and then mistakes this for a zero result or there is something not being intialised between simulations that can sometimes result in a failed simulation.
The other glitch I sometime see is when the current designed value is outside the range you want to optimize for. When this occurs OR can show a completely blank graph (zero simulations). To get around this I first modify the design so that what I want to optimize is in the middle of the range I want to use.
A nice to have change would be that the configuration defaults to the first one, it would be nice if it defaulted to the motor you had loaded. I keep forgetting to select the motor, then I optimise and realize I forgot to change the motor. Due the issue with the current value (above) I cannot get a result out of the optimizer. I then need to close the optimizer (if I had hit apply then I need to undo that), only then can I give it another shot (would not be much of an issue if it wasn't for the other glitch).
I've not jumped on this earlier because I didn't have much time. But I could look now.
Could you attach an OR file and instructions on how to demonstrate your concerns? I'll be glad to look into it after that. I've been wanting an excuse to dive into the optimization internals for a while.
Wes
I would rather keep that particular sim to myself for now. I should be able to come up with another example I'm sure.
As request, attached zip file has the OR sim. There are 2 print screen in there that show the values you need to set.
View attachment 275183
You gave no numerical information on how you conducted your optimizations but the above reply has the information I was going to suggest.
I find the current input window for changing the optimization parameter inputs confusing, and that's probably the source of the strange plot. The OR optimization seems more complex than it needs to be IMO. A simple variation of +/- total mass is what you need to consider for most cases and in the simplest case leave it to the designer to decide where the mass reductions or additions will happen.
Bob
With regard to the optimum mass, you also limited the stability margin to 1. The optimum mass with the stability margin option = 1 is 3.82 oz. so there is no solution below this value. Remove the stability margin requirement and the optimization will be the minimum mass, but the resulting rocket design might be unstable.As request, attached zip file has the OR sim. There are 2 print screen in there that show the values you need to set.
View attachment 275183
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