Final weight of DX3 2.6" rocket, motor ok?

[rsbhunter]

Have clear coat coming, will put on 3 light-medium coats...weight of rocket, motor casing, chute, Jolly Logic and chute protector is right now at 1.8 lbs (24 oz) I've ordered 2 Aerotech F40-W7 kits for the ARO 29/40-120. Does anything sound way off ? I haven't seen any posts about adding nose weight, but this is my first mpr..are there any "normal" amounts of weight a rocket gains during the build process? .rsbhunter

 

[David_Stack]

Review of that model on "Rocket Reviews", and the author's came in at 18.2 oz sans motor and Jolly Logic (you didn't specify, is it one of the Jollly Logic altimeters, or the Chute Release?) https://www.rocketreviews.com/madcow-rocketry-dx3-by-mike-caplinger.html

As for nose weight, remove the motor and determine where the model balances (C/G). Enter that distance from the tip of the nose cone into your Open Rocket simulation as a C/G override, and verify that it is still suitably forward of the CP. If not then you would likely need to add weight to increase your stability.

 

[rsbhunter]

Awesome. !! Your answer was concise and to the point! Thank you very much..and it is the JL chute release......rsbhunter

 

[rsbhunter]

How do I override cg? I'm in open rocket?

 

[David_Stack]

The top level component in your simulation is usually labeled "Stage" (by default I believe).

Select "Stage", then "Edit". A new window will open with line items that allow you to override the Mass and Center of Gravity.

I'm running an older version of Open Rocket, but I believe it should look something like the attached.

 

[rsbhunter]

Ok, got there... entered 26.5 for cg(it is) and changed weight to 18.8...stability shows to be 1.81 cal.? It says " cg is measured from front end of stage? Nose cone or body tube? Thanks for all the help, I'm filing it away to hopefully retain it..rsbhunter

 

[David_Stack]

Ok, got there... entered 26.5 for cg(it is) and changed weight to 18.8...stability shows to be 1.81 cal.? It says " cg is measured from front end of stage? Nose cone or body tube? Thanks for all the help, I'm filing it away to hopefully retain it..rsbhunter

"Stage" in the case of your DX3 sim is the entire airframe/rocket, so in this instance the front end of the stage is the tip of the nose cone.

 

[rsbhunter]

What is a good caliber #? Also, would threading all thread into the nosecone help move the cg further from the cp? Thanks again, I know you must get tired of all the questions..... I didn't mind learning the way how to do it on lpr, but learning the hard way on a $100 rocket is a sad day! rsbhunter