ThirstyBarbarian
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I have a question about the stability of a Mega Der Red Max that I have modified. It's the one with the fin pods: https://www.rocketryforum.com/showthread.php?64212-REVIVED-Pods-on-Mega-Der-Red-Max
Now that I have extended the fins and added the pods, the CG has sifted aft, and the CP is harder to figure because of the complexity of the pods. Also, the overall weight of the rocket has increased. So I need to check the stability of the new configuration.
I took an OR file for a MDRM that I found in another thread, and I approximated the shape of the fins. I don't think there is a way to add fin pods in OR, so I just added an approximate profile shape of the pod to the edge of the fin. This did shift the CP back slightly from the file I had copied. Then I weighed the rocket, and I balanced it to find the CG --- then did a mass override and CG override for the whole rocket.
In the original file I had copied, the stability was 1.56 without motors, and 1.3 with a G80. In my modified version, the stability is .735 without motors, and .615 with a G80. So the stability has been altered significantly.
Unfortunately, if I add very much nose weight, I'm going to get out of the weight range for G motors and have to move to H motors, and I am not L1 (Maybe I've just built my L1 rocket inadvertently?).
Are there other considerations for the stability of this rocket? Do the fin pods further decrease stability by having weight and drag at the fin tips? Is there base drag to consider? How would I simulate these things or take them in to consideration if they cannot be simulated?
One of the great appeals of the stock MDRM are the awesome slow and stable flights. I'm hoping to be able to still have that and keep the option to fly on G motors, so if I can have it safely stable with minimal nose weight added, that would be great.
Any advice is greatly appreciated!
Here's a screen grab of OR:
I'm attaching the OR file I've modified.
Now that I have extended the fins and added the pods, the CG has sifted aft, and the CP is harder to figure because of the complexity of the pods. Also, the overall weight of the rocket has increased. So I need to check the stability of the new configuration.
I took an OR file for a MDRM that I found in another thread, and I approximated the shape of the fins. I don't think there is a way to add fin pods in OR, so I just added an approximate profile shape of the pod to the edge of the fin. This did shift the CP back slightly from the file I had copied. Then I weighed the rocket, and I balanced it to find the CG --- then did a mass override and CG override for the whole rocket.
In the original file I had copied, the stability was 1.56 without motors, and 1.3 with a G80. In my modified version, the stability is .735 without motors, and .615 with a G80. So the stability has been altered significantly.
Unfortunately, if I add very much nose weight, I'm going to get out of the weight range for G motors and have to move to H motors, and I am not L1 (Maybe I've just built my L1 rocket inadvertently?).
Are there other considerations for the stability of this rocket? Do the fin pods further decrease stability by having weight and drag at the fin tips? Is there base drag to consider? How would I simulate these things or take them in to consideration if they cannot be simulated?
One of the great appeals of the stock MDRM are the awesome slow and stable flights. I'm hoping to be able to still have that and keep the option to fly on G motors, so if I can have it safely stable with minimal nose weight added, that would be great.
Any advice is greatly appreciated!
Here's a screen grab of OR:
I'm attaching the OR file I've modified.
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