3" Black Fly Nose Weight

[Crazyrocket]

Just bought a MAC Performance 3" black fly rocket with the standard Pinnacle nose cone as well as a nose cone av. bay. Everything is just about assembled except for the av bay in the nose cone. I am curious about nose weight for this rocket. The instructions state that CP is 26.3". I have modeled the rocket in both OpenRocket and Rocsim based on files from other forum members. All of the CPs locations are different. CP from OpenRocket is 27.5" and RocSim is 30". Based on this, the nose weight I need to add can vary drastically. Using ~4oz of nose weight in Rocsim give me ~1 caliber of stability on most motors (lowest is ~.7). In OpenRocket is would need ~8 oz of weight. I have not determined the weight for the 26.3" CP in the instruction. These weights are with the av bay included which adds a little bit of weight.

Just wondering what others have put in the nose for the 3" black fly. The RocSim CP looks to be right compared to the instructions CP. Anyone out there have any better data I could use?

Thanks!

 

[Nytrunner]

Let's ask the creator @mpitfield

 

[mpitfield]

Just bought a MAC Performance 3" black fly rocket with the standard Pinnacle nose cone as well as a nose cone av. bay. Everything is just about assembled except for the av bay in the nose cone. I am curious about nose weight for this rocket. The instructions state that CP is 26.3". I have modeled the rocket in both OpenRocket and Rocsim based on files from other forum members. All of the CPs locations are different. CP from OpenRocket is 27.5" and RocSim is 30". Based on this, the nose weight I need to add can vary drastically. Using ~4oz of nose weight in Rocsim give me ~1 caliber of stability on most motors (lowest is ~.7). In OpenRocket is would need ~8 oz of weight. I have not determined the weight for the 26.3" CP in the instruction. These weights are with the av bay included which adds a little bit of weight.

Just wondering what others have put in the nose for the 3" black fly. The RocSim CP looks to be right compared to the instructions CP. Anyone out there have any better data I could use?

Thanks!

Let's ask the creator @mpitfield

Hi Crazyrocket,

I received your PM, but I will post the data here from my RockSim and OR when I get home later today, which is valid. On a side note, although I came up with the concept and initial BF, Rocketry Forum member gfunk is the person who upscaled it and has more data on the 3" version.

 

[gfunk]

Hi Crazyrocket,

I received your PM, but I will post the data here from my RockSim and OR when I get home later today, which is valid. On a side note, although I came up with the concept and initial BF, Rocketry Forum member gfunk is the person who upscaled it and has more data on the 3" version.

Good question, great rocket! I have 13 flights on my 3" Fly, it's a favorite for sure. I use the WM nosecone so my amount of nose weight will be different.

I have flown down to ~0.8 calibers of stability in OR without issue from a long, 8' rail in calm winds. Most flights right at 1 cal.

You might also plot stability vs altitude in OR, though it's kind of hard to break Mach with a 3" fly, so you probably won't need to worry about the stability dip at the Mach transition.

 

[Crazyrocket]

What did you use for the CP in your rocket? OpenRocket was around 27.5" and rocksim was ~30". Instructions stated 26.3". Since you have had many good flights, I would probably use your CP to determine the nose weight.

Thanks!

 

[Tobor]

Hello Crazyrocket,
I also have a 3" BF with the Pinnacle NC. I did not need nose weight as I installed my EggFinder GPS tracker in the NC using SMT's 54mm End Mount Sled and a Turnigy 1000 mAh 2S LiPo pack. Total weight with anchor plate (plywood CR w/54mm I.D.) and sled base plate (plywood bulkplate) is 5.63 oz. OpenRocket calculates the stability at 1.02 cal on an AT I195J motor and 2.3 cal empty.