FWIW, I played around with it. I removed all of the overrides except the stage weight. By switching to 4 fins and adding 200g of weight, I got the cal to 1 with the engine. I know that's not helpful to you now. I'm sure neil can be more helpful.
So: as previously stated, but problem is that once you override the entire stage, changing the nose weight *inside* the stage has no effect. For now, there are two hack ways to get around this. I am hopeful that a cleaner solution will be implemented in the program in the future.
EDIT: I forgot to remove the motor during certain of the below steps, although I seem to have gotten to (approximately) the correct answer anyway. Start with following post instead, for quicker answer.
1) Add a new stage to the rocket. Name it "Nose + weight", and set "Separation" to "Current Stage Ejection Charge ("Never" also works):
2) Drag the new stage up to the front:
3) Now move the nose cone to the new stage:
4) Now, the overrides for the Stage are wrong, because it no longer includes the nose. So I will ask you to re-measure the stage mass and CG without the nose, everything else the same. I can estimate the mass pretty well (5950g), but CG is harder. For now I'll just guesstimate it at 33". Remember that CG for the stage is now measured from front of body airframe, not including nose cone! Here's where we are now:
If everything was done correctly, the total rocket mass and CG should match the original measured values (I'm too lazy to go back and check.
5) Now the easy part: Add a mass object to the nose cone and adjust as needed:
So I show about 37 oz in the nose to achieve 1 caliber of stability. Yeah that's a lot, and it probably agrees pretty well with your original measurements. I don't think it's crazy for a short 20 lb rocket though. Experienced HPR guys can comment here. Also I approximated the weight position; in real life it'll be distributed around the nose a bit differently. But this is probably a good estimate.
If you enter the rocket this way in the first place (nose in separate stage) then it is easy to do the nose weight approximation in OR before you start pouring shot. Of course you will need to confirm everything with real measurements when you're finished.
I'll do another post describing hack #2 later. For now the important thing is that it validates your initial finding that this thing will need plenty of nose weight to fly with that motor.
ARGH, I did the whole thing above with the motor in! Might have totally screwed up the numbers. Let's double-check it using hack #2, which is definitely easier although it has its own downsides.
1) Make a note of stage measurements: mass 230 oz, CG 50". Now disable the overrides on the stage:
First observation: Is 69 oz difference between original model weight and actual measured mass really correct? When you measured for the override did you do it *without* the motor?
2) Let's assume it's all correct, even though it sounds doubtful to me. We have 69 oz difference to make up between model and actual. So we'll add a 69 oz mass object and adjust its position until the CG matches the 50" original measurement. It doesn't matter which component we add the mass object to; I'll add it to the top of the Fore Recovery Airframe Section. I get its final position at 29.5" from top of the parent component.
3) Now you can add your noseweight and adjust. Because the total rocket mass has not been overridden, it will factor in the added mass appropriately. This time, I achieve the same 1.02 stability margin with...
35 oz! Well whaddya know, I guess I didn't screw up hack #1 in the previous post. 35 oz vs. 37 oz might be accounted for just because I positioned the weight slightly differently.
Bottom line: you're gonna need 2+ pounds of weight in the nose to fly that configuration.
Wow that was a very nice amount of information that you gave me, Neil. I appreciate it very much. I will read over this better tonight when I’m off work and try to digest it all. Boy howdy, Loc says this rocket flies on L motors, but do they really expect you to stick two lbs of weight in the nose to accomplish that! That is a ton of weight. I’m thinking about lengthening it instead by about 18”.
Yes, my rocket is 69 0z heavier than the file I received. Mine had the two altimeters, three batteries and some added plywood to hold batteries switches etc added to it. I also, used a number of quick links and have a home made thrust plate.
My understanding is that a cal of <1 means the CG is too close to the CP and might somersault because the aft wants to go faster than the fore. Over 2 is overstabilized and not reaching it's full potential (too much NC weight or massive fins). Sorry if I got this backwards. Of course this all depends on which motor you use so the cal without the motor is not telling because motors have different weights.
1-2 cal stability is a rule of thumb. There are many possible modifiers. @Nytrunner prefers to go with 10% of the length of the rocket, which is another good rule of thumb and covers modifier #1 below.
1) longer skinnier rockets need more margin, short stubby rockets need less.
2) rockets that will go supersonic will need considerably more
3) In calm conditions, you can do with a bit less margin
Most of the time .97-ish will fly perfectly fine. However, on your Big Nuke, 1 cal is 5.54" which is quite a bit less than 10% of the rocket length. I personally would prefer to have more safety margin than that (I'd probably aim for 1.1-1.2, minimum). But I'm just an LPR guy, don't take my word for it.