Estes V2 nose cone weight

[amiliv]

I'm working towards finishing Estes V2, and just made OpenRocket model of it. Without paint on it yet, the rocket fully assembled (with nylon parachute, nomex blanket and Aero Pack retainer) currently sits at 184 grams, and has CG at 327mm without motor. Both actual measurements (not OpenRocket estimates). This includes one pack of clay for nose cone weight that came with it packed tightly in the nose cone's tip. OpenRocket calculated CP to be at 396mm. This gives barely 0.5 cal stability with D12, and 0.3 cal with F12 motor.

Does CP OpenRocket calculated (396mm) sounds about right for this model? Or should I be getting more clay to put into the nose cone?

 

[Funkworks]

If you're going to use an F12 motor and a metal retainer, adding nose weight sounds like a very good idea. I might be able to plug in my own V2's measurements in OpenRocket later today and compare, but in the meantime: https://ahrocketry.com/AHRocketry/Rocket_Stab_1.html

"...for very long, skinny rockets, more than 10 calibers might be needed for stability and for short, fat rockets, less than half a caliber may be enough. Designs like the V2 are a challenge for Barrowman’s equations..."

 

[Funkworks]

So I'm over 0.5 cal, but I don't have the retainer, and have a 7g metal swivel clip attaching the shock cord to the nose cone. Otherwise the builds and contents are similar. Modelling results with and without boat tail differ.

 

[Nytrunner]

If your CP-CG distance is ~8-15% of the rocket length, it should fly alright

 

[amiliv]

So I'm over 0.5 cal, but I don't have the retainer, and have a 7g metal swivel clip attaching the shock cord to the nose cone. Otherwise the builds and contents are similar. Modelling results with and without boat tail differ.

My sim was made with boat tail. Plus the "fake tube trick" to go around OpenRocket not directly supporting adding fins to boat tails; that I hope I did the trick correctly. I should have probably included my ORK file in my original post (attaching it now); though it is still work in progress, not a final file.

The weight and CG override includes the weight of retainer, current nose weight, (different) parachute, swivel, Nomex blanket, etc. It could be additional weight of paper (I papered the fins) and metal retainer simply needs to be balanced with more nose weight. Oh well.

If your CP-CG distance is ~8-15% of the rocket length, it should fly alright

It sits at more like 3% (for F12) and 6% (for D12) currently, with E motors somewhere in between. Assuming OpenRocket's estimate for CP is about right, I guess this bird will be getting bit more nose weight.