I have no involvement in this project, but one of the easiest ways to calculate the CG of an assembly is to sum the CG's of the component parts (with a little manipulation based on their relative locations).

You mean, why did we choose 71% as the position of the CG, or why we bothered at all? :D

The 71% location is a "best guess" ball-park figure for "getting the location close". It's not accurate, and can probably use some tweaking in the future. I'm already thinking that the value will be different with each shape, as some have more "bulk" in one direction than the other. It will help in the total balance of the model because RockSim uses these figures to work from, as a "starting point". It will, in the long haul, improve the flight simulation reports of our designs.

New Design -- Lune R-1 Plus 1
 

Lune R-1 Plus 1

A simple booster added to the stock Lune R-1 kit for two staged flights. Only mod to the Lune R-1 sustainer is to move the rear centering ring slightly forward to clear the tube coupler on the booster. Fins are the same KV-35 fin set on the booster only reversed for a seamless transition.


Length: 26.275"
Diameter: 1.040" (ST-10)
Span Dia: 4.040"
Weight: 1.715 oz


B6-0 / A8-5..........637'.........Dv 11 FPS.........36" x 1/8" rod
B6-0 / B6-6..........906'.........Dv 19 FPS.........36" x 1/8" rod
C6-0 / B6-6.......1,292'.........Dv 5 FPS...........36" x 1/8" rod
C6-0 / C6-7.......1,728'.........Dv 30 FPS.........36" x 1/8" rod

May want to swap out the parachute for a streamer on high altitude flights .....

:)

Thanks Bill

I guess it's pretty obvious but I'm an SLS freak.

I'm finding I have a few designs including some that have been built and flown that I entered into RockSim and either posted them to other threads on the forum or just neglected to consider posting to BARCLONE. Shame on me .....

The next design I'll rework is an FSI rocket that was one of my favorite two stagers. I have to rework it with Semroc parts because all my FSI rockets were entered into RockSim 5 and I used FSI parts when I entered the data to create the files.

.

New Design -- 2009 Test Rocket B
 

OK, so not exactly a "new" design, just something to test the new components with. Actually doesn't have bad C6-7 performance.

Length: 19.85"
Diameter: 1.04" (ST-10)
Fin Span: 4.54"
Weight: 1.24 oz


A6-4Q......213'......Dv 23 FPS......36" x 1/8" rod......Parachute reefed
A8-3.......240'......Dv 10 FPS......36" x 1/8" rod
B4-4.......574'......Dv 27 FPS......36" x 1/8" rod......Parachute reefed
C6-7......1336'......Dv 18 FPS......36" x 1/8" rod


Enjoy!

NCDATA Error
 

I just spotted an error in the NCDATA file, while transferring the data for transitions and tailcones. The "Rear OD" and "Insert OD" dimensions for the ST-20 series appear to be the same as the ST-18 series, with the exception of the first entry.

That's why we need additional pairs of eyes looking through these files besides ours. This is an on-going process, and there might be more errors before all of this data is ready.

We now return you to your regularly-scheduled interruptions... :o

TRDATA File (Reducers and Tailcones)
 

Here's the new TRDATA file, containing all of the wizard-gerated reducers and tailcones in the SEMROC lineup. Any nose cones that we could not put into the NCDATA file will likewise not be found here.

We still need you to look through the data before committing to the installation, however, barring any last-second "gotchas", the file should be usable.

Jay,

Because Craig said to why of course! :chuckle:

Actually, I think we are just shooting for as much accuracy as possible. As Craig mentioned, 71% is an estimate based on general shape of cones / transitions. Since we added "reversed" transitions and tail cones, it seemed logical that the CG location would switch orientation as well since the majority of the mass in the components was now also reversed. Again, these estimations are up for review / discussion and can be overridden and calculated by Rocksim.

... Bill

Craig - nice catch! Yeah, the more eyes looking at these files the better!

After a while, one can get a little bleary eyed working directly with the CSV files! :eek:

I'm trying my best to review parts in design mode in Rocksim prior to submitting files to forum. But there be a lot of parts in them there files. :D

... Bill