I'm working on a rocket, and am running into some major discrepancies, and I'm looking for advice.
I find that the actual weight of the rocket with NO ENGINE is 4.55oz, while Rocksim says it should be 4.26. Okay, the difference is likely to be the glue weight. However, the measured CG is 13.375" from the rocket nose, whereas Rocksim says it should be 11.55". I manually added a mass object to the rear of the rocket because the way the tube sizes are, likely most of the glue weight is there. This brought the CGs to 13.375 actual vs 12.52" in Rocksim. If I bump the weight up to .9oz from .45 then the numbers are close enough (13.375 actual vs 13.33 in Rocksim). But that is way heavier than the rocket actually weighs.
I used actual part weights and manual override instead of rocksim's database weights.
I'm inclined to go with actual weight and measured CG vs Rocksim, but I have to wonder why the big difference?
If I add the engine in and re-measure the actual CG, then it moves backwards, but Rocksim is still .75" off of actual measured CG. What gives?
I'm going to spin test the rocket today, but I suspect that I am going to have to increase the size of the rear fins to move the CP back to ensure the rocket is stable enough to fly.
I find that the actual weight of the rocket with NO ENGINE is 4.55oz, while Rocksim says it should be 4.26. Okay, the difference is likely to be the glue weight. However, the measured CG is 13.375" from the rocket nose, whereas Rocksim says it should be 11.55". I manually added a mass object to the rear of the rocket because the way the tube sizes are, likely most of the glue weight is there. This brought the CGs to 13.375 actual vs 12.52" in Rocksim. If I bump the weight up to .9oz from .45 then the numbers are close enough (13.375 actual vs 13.33 in Rocksim). But that is way heavier than the rocket actually weighs.
I used actual part weights and manual override instead of rocksim's database weights.
I'm inclined to go with actual weight and measured CG vs Rocksim, but I have to wonder why the big difference?
If I add the engine in and re-measure the actual CG, then it moves backwards, but Rocksim is still .75" off of actual measured CG. What gives?
I'm going to spin test the rocket today, but I suspect that I am going to have to increase the size of the rear fins to move the CP back to ensure the rocket is stable enough to fly.